Results 31 to 40 of about 1,056,070 (342)
Experimental research into the effect of some operation factors and rock properties on the rate of penetration [PDF]
, 2020 Purpose. The purpose of this research is to investigate the effect of weight on bit (WOB), rotary speed (RPM), and some rock properties on the rate of penetration (ROP). Methods.
Ali, Mahrous A.M. +4 more
core +1 more source
British Educational Research Journal, EarlyView., 2023 Abstract Children's relationship with time in preschools is an under‐researched area. Young children rarely know how to measure time using a clock, but their experiences of time may contribute to understanding children's well‐being and debates about quality in preschools.
Kristín Dýrfjörð +3 more
wiley +1 more source
Full and half-wavelength ultrasonic percussive drills [PDF]
, 2018 Ultrasonic-percussive drills are a leading technology for small rock drilling applications where power and weight-on-bit are at a premium. The concept uses ultrasonic vibrations to excite an oscillatory motion in a free-mass, which then delivers ...
Harkness, Patrick +2 more
core +1 more source
Research on multi-boom coordinated drilling technology for hard rock tunneling
Meitan kexue jishu, 2023 In order to realize the mechanized construction of hard rock tunnel boring, and improve the construction efficiency of three-boom drilling jumbo when applied to hard rock tunnel boring, the research and analysis are conducted on the positioning accuracy ...
Menghao CUI +5 more
doaj +1 more source
Improvment of safety conditions of unstable rock slopes through the use of explosives [PDF]
, 2008 The paper discusses operations aimed at creating a safer natural or man made rock slope by artificially inducing the displacement of unstable elements by blasting.
Casale, M. +2 more
core +3 more sources
Study on Rock Breaking Characteristics of a Hybrid Bit
Shiyou jixie, 2020 Existing conventional PDC and roller bits are unable to meet the rock breaking requirements in deep and hard formations, difficult-to-drill formations and soft and hard formations.
吴泽兵 +4 more
doaj
Study on Drill String Stick-slip Vibration Pattern Under Bit-Rock Interaction
Shiyou jixie, 2023 Stick-slip vibration leads to high-frequency shear stress on drill string and premature fatigue of drill string.Therefor,the torsional vibration model of drill string system considering bit-rock interaction was built by coupling the bit-rock interaction ...
Xing Xuesong +4 more
doaj
Innovative aspects of underground coal gasification technology in mine conditions [PDF]
, 2018 Purpose. Development of innovative approaches in technological and technical solutions improvement for coal seam gasification. Methods. Carrying-out of native and world experience in the coal reserves development by underground gasification technology ...
Dychkovskyi, R +4 more
core +1 more source
Drilling Performance of Rock Drill by High-Pressure Water Jet under Different Configuration Modes
, 2017 In the rock drilling progress, the resistant force results in tools failure and the low drilling efficiency; thus, it is necessary to reduce the tools failure and enhance the drilling efficiency.
Songyong Liu +2 more
semanticscholar +1 more source
Applied Sciences, 2021 This paper analyses the construction time and advance rate of a 3 km long drill and blast tunnel under various geological conditions using an upgraded NTNU drill and blast prediction model. The analysis was carried out for the five types of Korean tunnel
Yangkyun Kim, Sean Seungwon Lee
doaj +1 more source