Hartley spectral analysis of self-potential anomalies caused by a 2-D horizontal circular cylinder

The real spectral analysis of SP anomalies due to 2-D horizontal circular cylinder is carried out using Hartley transform. The Hartley transform is an alternate means of realizing spectral analysis in real domain unlike the Fourier spectral analysis. The Hartley transform yields a straightforward interpretation of SP anomalies caused by horizontal circular cylinder wherein all the parameters are derived independently as a function of frequency. A theoretical example illustrates the procedure. The effect of random noise, up to 10% of white Gaussian noise, on the interpretation scheme was also studied and found to be of negligible. The field example of the ??Sulleymonkey?? anomaly in the Ergoni copper district, Turkey exemplifies the applicability of the proposed method.     

Estimating width of the stable channels using multivariable mathematical models

Predicting behavior and the geometry of the channels and alluvial rivers in which the erosion and sediment transport are in equilibrium is one of the most important topics in river engineering. Various researchers have proposed empirical equations to estimate stable river width (W). In this research, empirical equations were examined and tested with a comprehensive available data set consisting of 1644 points collected from 29 stable rivers in various parts of the world. The data set covers a wide range of flow conditions, river geometry, and bed sediments. This data set is classified in two groups (W < 600 m and W ≥ 600 m) for presenting the new models. The new linear and nonlinear multivariable equations were fitted to these two groups, and the best models were selected by preliminary tests and diagnostic determined for each group. The determination coefficient of these models ranged from 0.87 to 0.96. The results show that the models presented in this paper are more accurate with respect to the previously presented models. In the second part, “Artificial neural networks,” perceptron was used and a new methodology for estimating stable channel width was developed. Comparison of the statistical methods presented in this paper and the results of perceptron neural network revealed preferential recent method.     

The permeability of fault zones: a case study of the Dead Sea rift (Middle East)

Fault zone architecture plays an important role in flow regimes of hydrological systems. Fault zones can act as conduits, barriers, or conduits/barrier systems depending on their spatial architecture. The goal of this study is to determine the fault-zone permeability structure and its effect on the local hydrogeological system in the Dead Sea fault system. Permeability was measured on small-scale outcrop plug samples at four faults along the Dead Sea fault system, and large-scale slug tests in four boreholes, in different parts of the fault, at Yair fault in Israel. The research results show that values in the damage zone are two to five orders of magnitude higher than those of the fault core (~3.5?×?10^?10, 1?×?10^?15 m² respectively), resulting in an anisotropic permeability structure for the overall fault zone and preferable flow parallel to the fault. A set of injection tests in the Yair fault damage zone revealed a water-pressure-dependent behavior. The permeability of this zone increases when employing a higher water pressure in the fault fracture-dominated damage zone, due to the reopening of fractures.     

Barnacle fouling in the Mediterranean sponges Axinella polypoides and Axinella verrucosa

Secondary metabolites protect many marine sponges (Phylum: Porifera) from settlement by fouling organisms. Previous studies on the subtidal demosponge Axinella verrucosa collected in the Western Mediterranean led to the isolation of compounds that inhibited the settlement of cyprids larvae of the intertidal barnacle Balanus amphitrite, and the enzyme chitinase, which plays a key role in the molting cycle of crustaceans. However, in a field survey conducted at three locations in Israel, Eastern Mediterranean Sea, we observed that A. verrucosa is fouled by the subtidal barnacle Balanus trigonus, a previously unknown association. Settlement inhibition assays using B. amphitrite with chemical extracts from Israeli A. verrucosa and Axinella polypoides, a sympatric, congeneric sponge that seems not to be fouled by B. trigonus, showed that cyprid larvae of B. amphitrite were inhibited by the extracts of both sponges from settlement at concentrations several magnitudes lower than natural volumetric extract concentration in the sponges. These results indicate that, unlike the intertidal barnacle B. amphitrite, the subtidal B. trigonus is unaffected by the compounds from A. verrucosa, stressing and underlining the importance of using suitable target organisms (i.e. from the same habitat) to test for ecologically relevant antifouling activities.     

Rotation–translation mechanisms for upper-bound solution of bearing capacity problems

To obtain rigorous upper-bound solutions for the bearing capacity of strip footings subjected to combined loadings, a new collapse mechanism consisting of three rigid blocks undergoing impending rotational or translational movements is proposed. The proposed mechanism improves the efficiency of the previously-developed rigid block mechanisms to account for eccentric loading condition in restricted bearing capacity problems. The comparisons show a good agreement between the results obtained using the present method and those of the known solutions. The effectiveness of the proposed mechanism was examined through investigating the bearing capacity of eccentrically loaded strip footings over thin layer foundation soils.