Asian Transactions on Engineering
Volume: 03, Issue: 01, March 2013
Title: New Shapes of Baffle Piers Used in Stilling Basins as Energy Dissipators
Author(s): Ashraf BESTAWY
Paper ID: ATE-70309017
Pages: 1 - 7
Abstract: Energy dissipation arrangements are the most important part in the design of a spillway for a dam. Various types of baffle piers and stilling basins have been tried so far. However, the hydraulic jump type-stilling basin is found to be the most efficient one. The main goal of this study is to introduce a???shape of baffle pier, which has maximum energy dissipation. In this study, 14 different models of baffle piers were used for dissipating water energy downstream a heading up structure. One row of each model of baffle piers was used with a fixed position. Bed material used for runs was a uniform sand d50=0.8 mm. The dimensions of the scour hole for each run were measured and used for the comparison between the performances of the used models for energy dissipation. Results in general show that, models with concave surfaces make the flow to change its direction more than the others with low turbulence intensity in recirculation zone downstream baffle piers and dissipate more energy than other forms. This leads to a stable hydraulic condition and shorter stilling basins. In addition, the study shows that the vertical semi-circular section (model No. 7) has the most effect among other tested models for dissipating water energy.
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Title: An experimental investigation of surface behavior of Al2O3-TiO2 coated parts of a diesel engine
Author(s): Hanbey Hazar and Ugur Öztürk
Paper ID: ATE-60303014
Pages: 8 - 12
Abstract: This study examined the effects of Al2O3-TiO2 surface coating on the combustion chamber components of a diesel engine. The piston surface, cylinder head, exhaust and inlet valves of a single cylinder, four-stroke diesel engine were coated with Al2O3-TiO2 (87-13) oxide based ceramic composite. The surface coating was applied to a thickness of 250 µm using an atmospheric plasma spray method. NiAl (50 µm thickness) was employed as bond layer for the piston and the valves. Coated and uncoated surfaces were tested under the same conditions for 150 hours. After testing, the surface treatments were examined using a scanning electron microscope (SEM) and optical microscope. According to test results, coated samples have showed fewer deformations, wear lines and less erosion in comparison to uncoated samples. A positive effect was also observed on the cylinder bore and piston rings. The results indicate that coating the pistons and valves with oxide based ceramics contributed to increasing the mechanical lifespan of the samples.
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Title: Longitudinal and Lateral Dynamics Control of a Small Scale Helicopter Using Adaptive Backstepping Controller under Horizontal wind Gusts
Author(s): Tushar Kanti Roy
Paper ID: ATE-80305017
Pages: 13 - 22
Abstract: The problem of stabilization of longitudinal and lateral dynamics of an unmanned autonomous helicopter (UAH) for hovering flight mode in a gusty environment is considered in this paper. The controllers design is based on generic linear model which successfully describe the behavior of most small scale helicopters. A backstepping design procedure is used to design the adaptive controller for longitudinal and lateral dynamics based on control Lyapunov approach. For comparison purposes we also design another controller based on the linear quadratic regulator (LQR) criteria. The simulation results demonstrate that the proposed adaptive controllers can effectively attenuate the gust effects and achieve rapid and accurate longitudinal and lateral position in the gusty environment.
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