Image enhancement using fuzzy intensity measure and adaptive clipping histogram equalization

Image enhancement aims at processing an input image so that the visual content of the output image is more pleasing or more useful for certain applications. Although histogram equalization is widely used in image enhancement due to its simplicity and effectiveness, it changes the mean brightness of the enhanced image and introduces a high level of noise and distortion. To address these problems, this paper proposes image enhancement using fuzzy intensity measure and adaptive clipping histogram equalization (FIMHE). FIMHE uses fuzzy intensity measure to first segment the histogram of the original image, and then clip the histogram adaptively in order to prevent excessive image enhancement. Experiments on the Berkeley database and CVF-UGR-Image database show that FIMHE outperforms state-of-the-art histogram equalization based methods

Inversion of Shear Wave Anisotropic Parameters in Strongly Anisotropic Formations

Deepwater reservoirs use highly deviated wells to reduce cost and enhance hydrocarbon recovery. Due to the strong anisotropic nature of many of the marine sediments, anisotropic seismic imaging and interpretation can improve reservoir characterization. Sonic logs acquired in these wells are strongly dependent on well deviations. Cross-dipole sonic logging provides apparent shear wave anisotropy in deviated wells, which can be far from the truth. Although anisotropic parameters have been successfully obtained using data from wells of several deviations or using single well data based on weak anisotropy approximation, estimation of strong shear wave anisotropy from single well data remains a challenge. Using sensitivity analysis, we find Stoneley wave velocity has good sensitivity to qSV and SH wave velocities in deviated wells. We create a linear inversion scheme to estimate shear wave anisotropy using SH, SV, and Stoneley wave velocities logged in one well. We first apply the method to laboratory measurements from boreholes of various deviations relative to the symmetry axis of an anisotropic material. We then apply the method to a field data set acquired in a deviated well. We also compute the vertical and horizontal shear wave velocity logs in this well using the inverted elastic shear wave constants.Massachusetts Institute of Technology. Earth Resources Laborator

Phagraphene: A Low-energy Graphene Allotrope composed of 5-6-7 Carbon Rings with Distorted Dirac Cones

Using systematic evolutionary structure searching we propose a new carbon allotrope, phagraphene, standing for penta-hexa-hepta-graphene, because the structure is composed of 5-6-7 carbon rings. This two-dimensional (2D) carbon structure is lower in energy than most of the predicted 2D carbon allotropes due to its sp2-hybridization and density of atomic packing comparable to graphene. More interestingly, the electronic structure of phagraphene has distorted Dirac cones. The direction-dependent cones are further proved to be robust against external strain with tunable Fermi velocities.Comment: 5 pages, 3 figure

Borehole Stoneley Wave Propagation Across Permeable Structures: Comparison Between Theory And Experiment

The attenuation of borehole Stoneley waves across a permeable structure (e.g., fractures or fracture zone) is correlated with the permeability of the structure. Using a simplified Biot theory, the structure can be modelled as a permeable porous layer intersecting the borehole. In order to study the effect of such a structure on Stoneley waves and to evaluate the theoretical model, we performed laboratory experiments using ultrasonic borehole models. The porous layer model is made of fine-grained sands with high permeability and porosity. The experiments are carried out with three saturant fluids: water, alcohol, and glycerol. The iso-offset Stoneley waveforms are recorded by moving the source and receiver across the porous layer. In this way, robust estimates of Stoneley wave transmission coefficients are obtained. The experimental transmission coefficients are compared with the theoretical coefficients calculated using the borehole and permeable zone parameters. There is good agreement between theoretical results and experimental results. For low viscosity fluid water and ethyl alcohol, the agreement is very good. For high viscosity fluid, glycerol, the agreement is fair with the experimental Stoneley attenuation higher than the theoretical value.Massachusetts Institute of Technology. Borehole Acoustics and Logging ConsortiumUnited States. Dept. of Energy (Grant DE-FG02-86ER13636

Finite Element Investigation on Load Carrying Capacity of Corroded RC Beam Based on Bond-Slip

The finite element (FE) investigation on the load carrying capacity of corroded RC beam is carried out based on the bond-slip between the steel bars and concrete. In the numerical simulation, several FE models of RC simply supported beam with different corrosion ratios were built using ANSYS. In these FE models, element of Solid65 was used to simulate concrete, element of Link8 was used for bars and element of Combin39 was adopted to simulate the bond and bond-slip between bars and concrete. The effect of corrosion ratio on bonding force between bars and concrete was simulated by adjusting the parameter of Combin39. Besides, the reduction of bars section area and decrease of bars yielding stress were also considered for calculating the load carrying capacity of corroded RC beam with different corrosion ratios. The results show that as the corrosion ratio increases the stiffness of corroded beam would decrease, slip between bars and concrete would be larger and ductile failure of RC beam would turn to brittle failure. The load carrying capacity of corroded RC beam would obviously deteriorate and descending speed is the fastest when the corrosion rate falls in the range of 4%-7%

Blood cholesterol in late-life and cognitive decline: a longitudinal study of the Chinese elderly

Mean difference in annual cognitive change for each mmol/L increment of lipid concentrations, stratified by age. (DOCX 13 kb