ultrasonic assisted drilling (usd) is new technique to drill difficult to machine materials. in this method, tool or workpiece vibrates with amplitude of few microns in addition to conventional drill bite rotation. in this experimental research, the bone was drilled both conventionally and using uad, then the thrust was measured in two methods at feed rates of 50, 75 and 125 mm/s and 500, 710 a...

Delamination is one of the most concern defects in drilling of composite material. Delamination depends on the factors such as feed rate, tool geometry and wear. The mechanics of drilling composite materials has been examined along with the quality of the hole and the effect of tool design parameters. The capacity of computerized tomography (CT) showing sample cross-section in a nondestructive ...

a three-year field experiment (2004-2007) was conducted on a silty clay loam soil at tajarak research station of hamedan to determine proper grain drill for wheat in hamedan dryland areas. in this study, three grain drills including: hamedani barzegar; sahalan kesht; and kesht gostar with wheat seed broadcasting and disking were used. the experiment was a randomized complete block design with f...

Received: December 18, 2015 Revised: September 29, 2016 Accepted: October 18, 2016 Abstract: Background: Aiming at the challenges in control and perdition of roof strata which caused by the complexity of coal mine roof, the force and vibration characteristics of drill bit have been analyzed considering the coupling vibration between drill bit and coal rock, and the characteristics of coupled vi...

INTRODUCTION Groundwater plays an important part in many regolith processes (chemical weathering, solute dispersion, etc.), but collecting groundwater data usually requires drilling that can be: a) expensive analyses for porosity, permeability, etc in addition to drilling costs; b) problematic rig availability and access to remote sites; c) under-sampled entire groundwater regimes characterised...

Apache Drill is a distributed system for interactive ad-hoc analysis of large-scale datasets. Designed to handle up to petabytes of data spread across thousands of servers, the goal of Drill is to respond to ad-hoc queries in a low-latency manner. In this article, we introduce Drill's architecture, discuss its extensibility points, and put it into the context of the emerging offerings in the in...