OBJECTIVES To compare the noise and vibration levels associated with three hand-held rock drills (pneumatic, hydraulic and electric) currently used in South African mines, and a prototype acoustically shielded self-propelled rock drill. METHODS Equivalent A-weighted sound pressure levels were recorded on a geometrical grid, using Rion NL-11 and NL-14 sound level meters. Vibration measurements...

We propose that a new type of drill, alternately known as a Fast Mechanical-Access Drill, or Coiled Tubing Drill for Ice (CTDI), be developed for polar research. The proposed drill is similar in concept to the latest coiled tubing (CT) drills used for commercial oil and gas development. CT drills use a metal or advanced-composite tube to deliver fluid downhole to a hydraulic motor that drives a...

Turbine is the most important part of hydro power plant which converts the potential energy of water into mechanical energy. The presence of silt in water erodes the turbine material. Erosion of turbine decreases the performance of turbine, life of the turbine as well as loss of power generation. This paper presents a new approach for the study of silt erosion of hydro turbine. In this study, w...

A power criterion for selecting the electric motor used in a gas turbine emulator is defined. The power criterion is derived in terms of the ratio of inertias between the gas turbine engine and the electric motor, rotational losses and load torque. The gas turbine emulator allows emulating the speed-torque behavior of a gas turbine engine. Using simulation models, we show that the steady-state ...

The Output power of wind turbine is determined by wind speed. The Output power can be adjusted by controlling the generator speed and pitch angle of wind turbine. When the wind speed below the wind turbine rated, the output power of generator can be maximized by controlling the generator speed at point of maximum power coefficient. When the wind speed above the wind turbine rated, output power ...

BACKGROUND To evaluate the effects of the amount of irrigation on heat generated during implant site preparation. MATERIAL AND METHODS Ten freshly dissected sheep mandibles were sectioned into 30 equal bone blocks and transferred into a heat-controlled water tank. Implant socket preparations were performed with four consecutive drills. Temperature measurements were performed with a thermocoup...

Combined Cycle Gas Turbine (CCGT) integrates two cyclesBrayton cycle (Gas Turbine) and Rankine cycle (Steam Turbine) with the objective of increasing overall plant efficiency. In modern gas turbine the temperature of the exhaust gases is in the range of 500 oC to 550 oC. Modern steam power plants have steam temperature in the range of 500 oC to 630 oC. Hence gas turbine exhaust can be utilized ...

We report preliminary findings on drill population ecology, feeding ecology, primate associations and conservation status in Korup National Park, Cameroon, based on analysis of data collected during 1,346 km (620 field hours) of trail patrols from February to June 2006. We encountered drills on 25 occasions and collected 304 fecal samples. Group size was estimated on four occasions (> or =25, >...