Multi-criteria Decision-making Approach for Environmental Impact Assessment to Reduce the Adverse Effects Of Dams

Water Resources Management - Environmental Impact Assessments (EIAs) of development projects are necessary to minimize negative impacts and maximize benefits. The objective of this paper is to...     

Positive holes in magnesium oxide. Correlation between magnetic, electric, and dielectric anomalies

Magnetic susceptibility measurements of high purity MgO single crystals (<50-wt. ppm transition metals) by means of a vibrating-sample magnetometer shows an anomaly at 800 K. At the same temperature the electric conductivity increases anomalously, the static dielectric constant epsilon increases from 9 to approximately 150, a pronounced positive surface charge appears, and Fe2+ in the MgO matrix oxidizes to Fe3+. The data are consistent with O2(2-) (peroxy) defects, representing self-trapped, spin-paired positive holes at Mg2+ vacancy sites. Diamagnetic at low temperatures, the holes start to decouple their spins > 600 K, probably forming at first V0 centers (two O- at an Mg2+ vacancy), then V- centers (single O- at an Mg2+ vacancy), and releasing mobile O- states. These O- represent itinerant charge carriers on acceptor levels near the O 2p-dominated valence band and conduct by O- /O2- valency fluctuations. The O- concentration is of the order of 8 X 10(19) cm-3.     

Performance of externally FRP reinforced columns for changes in angle and thickness of the wrap and concrete strength

In this study, the performance of axially loaded, small-scale, and fiber-reinforced polymer (FRP) wrapped concrete columns with various wrap angle configurations, wrap thicknesses, and concrete strengths was investigated through nonlinear finite element analysis. Three different wrap thicknesses, wrap ply angle configurations of 0°, ±15°, and 0°/±15°/0° with respect to the circumferential direction, and concrete strength values ranging from 3 ksi to 6 ksi were considered. An existing experimental study on FRP-confined circular columns in the literature was utilized to validate numerical analysis models. The finite element analysis results showed substantial increase in the axial compressive strength and ductility of the FRP-confined concrete cylinders as compared to the unconfined cylinders. The increase in wrap thickness also resulted in enhancement of axial strength and ductility of the concrete columns. The gain in axial compressive strength in FRP-wrapped concrete columns was observed to be higher for lower strength concrete and the highest in the columns wrapped with the 0° ply angle configuration.     

Certificateless designated verifier signature revisited: achieving a concrete scheme in the standard model

International Journal of Information Security - In a designated verifier signature (DVS) scheme, the signer (Alice) creates a signature which is only verifiable by a designated verifier (Bob)....     

Characterization and formation mechanism of nanocrystalline W–Al alloy prepared by mechanical alloying

Tungsten and aluminum elemental powders with composition W–20 wt.% Al were mechanical alloyed in high energy planetary ball mill. Structural and morphological changes of powder particles after different milling times were studied by X-ray diffractometer, scanning electron microscopy and microhardness measurements. Mechanical alloying of this system led to the formation of W–Al alloy as a result of formation of W/Al layered microstructure having faceted interface between layers. This alloy indicated high microhardness value of about 570 Hv.     

The effect of annealing on fracture behaviour of polycarbonate

Brittle fracture of polycarbonate (PC) caused by thermal pretreatment, is discussed in this paper. Further results on the thickness effect provide added support for the earlier work on this aspect. These results together with the temperature effect on the fracture of polycarbonate give a complete picture of brittle fracture in a tough material.     

The effect of temperature on the fracture of rubber modified polystyrene

Brittle fractures were obtained in rubber modified polystyrene over the temperature range −120 to 20° C using the surface notch method. When compared with single edge notch data, a thickness effect was apparent and this was described in terms of plane stress and plane strain fracture toughness values. The plane strain value agreed closely with that of the polystyrene matrix indicating that the constrained region showed no toughening effect. The relaxation process of the rubber was apparent in the plane stress toughness.     

Harmonic cut and regularized centroid transform for localization of subcellular structures

Two novel computational techniques, harmonic cut and regularized centroid transform, are developed for segmentation of cells and their corresponding substructures observed with an epi-fluorescence microscope. Harmonic cut detects small regions that correspond to small subcellular structures. These regions also affect the accuracy of the overall segmentation. They are detected, removed, and interpolated to ensure continuity within each region. We show that interpolation within each region (subcellular compartment) is equivalent to solving the Laplace equation on a multi-connected domain with irregular boundaries. The second technique, referred to as the regularized centroid transform, aims to separate touching compartments. This is achieved by adopting a quadratic model for the shape of the object and relaxing it for final segmentation.     

Spectral Lines of the Atomic-Fluorine Laser from 2 psi (absolute) to 5.5 atm

Various lines of atomic fluorine laser have been studied over a wide pressure range for determination of the relative intensity of each pressure-dependent line. In this investigation, the most probable laser pumping mechanisms have been verified.