The article presents the results of tribological research on most promising way to restore and increase wear resistance engine valves by developing a method gas nitriding. It is established that with increasing operating time guide bushings outlet connections out displacement axis forming surfaces hole. Characteristic significant axes inlet not detected, ie. their diameter hole 1.5 ... 3 times ...

Casing collapse is one of the major problems in oil fields, imposing a lot of costs on oil companies. This problem occurs not only at drilling times in some formations but also after the completion and production can lead to many problems. Analysis of the behavior of casing collapse in terms of geo-mechanics and solid mechanics could significantly meet the needs of the oil industry of Iran. In ...

Based on the acoustic wave finite element (AWFE) method, one can establish an AWFE method and study influence of mechanical parameters shale reservoir propagation characteristics. The different crack characteristics multi-physical coupling phenomena are studied by using gas cracks. To calculate shape position along near a side borehole, model compared with simulation results. reflection wavefor...

The development of retention prediction models for the seven ginsenosides (Rf, Rg1, Rd, Re, Rc, Rb2 and Rb1) on a polyvinyl alcohol (PVA)-bonded stationary phase at subambient temperatures is presented. The models were derived using multiple linear regression (MLR) and artificial neural network (ANN) using the logarithm of the retention factor (log k) as the dependent variable. Using stepwise M...

PURPOSE To determine the configuration of the anterior lamina cribrosa (LC) surface in eyes with different tilt axes. METHODS A total of 114 eyes (66 glaucomatous eyes and 48 healthy eyes) with tilted optic discs (ovality index > 1.3) were divided into vertical- and horizontal-tilt groups according to their optic disc tilt axis. Serial horizontal B-scan images of the ONH were obtained from ea...

PURPOSE We evaluated the prevalence and characteristics of the defects of the lamina cribrosa (LC) in high myopia and glaucoma, and compared them with control eyes using swept-source optical coherence tomography (SS-OCT). METHODS One hundred fifty-nine eyes of 108 participants were divided into four subgroups; high myopia with glaucoma (MG, 67 eyes of 46 subjects), glaucoma without high myopi...

PURPOSE To investigate the difference between two-dimensionally measured disc diameters (DDs) based on fundus images and three-dimensionally measured DDs based on enhanced depth imaging optical coherence tomography (EDI-OCT). METHODS The DDs were three-dimensionally measured on EDI-OCT images of optic nerve heads and two-dimensionally measured on near-infrared reflectance fundus images in 90 ...

While active fiber composites (AFC) based upon solid cross-section piezoelectric fibers are very useful for anisotropic activation of composites, they require high voltages and are constrained to non-conductive matrix materials. AFC’s based upon hollow cross-section piezoelectric fibers have shown promise to lower operating voltages and broaden the choice of possible matrix materials. This pape...