Although pneumatic down-the-hole (DTH) hammers have good performance of high penetration rate and minimal deviation tendency in the vertical section oil gas wells, they not been successfully used directional drilling due to drill tool wear wellbore disturbance. Herein, we developed a novel type DTH hammer with self-propelled round bit overcome technical difficulties drilling. Nonlinear dynamic ...

Objective: To compare the differences of clinical effect and complications of Percutaneous Nephrostolithotomy (PCNL), Ureteroscopic Pneumatic Lithotripsy (UPL) and Ureteroscopic Holmium Laser Lithotripsy (UHLL) in the treatment of upper ureteric calculi which is bigger than 12 mm. Methods: Totally 196 patients with upper ureteric calculi which is bigger than 12 mm in our hospital were selected ...

Aerostructures withstand cyclic mechanical loads and therefore, their design must fulfil surface integrity fatigue strength requirements. This paper studies the effect of pneumatic machine hammer peening on 7050-T7451 aluminium alloy. Specimens were peened using two different stepover distances (0.07 0.35 mm) initial offset (0.3 0.5 mm). A Kistler dynamometer was used to measure forces generate...

0 10 20 30 −50 0 50 100 150 r (mm) U (m /s ) x/DB = 0.2 0 10 20 30 −10 −5 0 5 10 r (mm) V (m /s ) x/DB = 0.2 0 10 20 30 −50 0 50 100 150 r (mm) U (m /s ) x/DB = 0.6 0 10 20 30 −10 −5 0 5 10 r (mm) V (m /s ) x/DB = 0.6 0 10 20 30 −50 0 50 100 150 r (mm) U (m /s ) x/DB = 1.4 0 10 20 30 −10 −5 0 5 10 x/DB = 1.4 r (mm) V (m /s ) Experiment Raman et al. LES/HPDF Liu et al. Merci et al. Fig. 1. Mean ...

The abilities of 26 marine and 12 other Pseudomonas-like strains of bacteria to grow on single carbon sources, their antibiotic sensitivities and complement of some enzymes of intermediary metabolism were numerically analysed and gave five phenons. Two phenons contained strains with more than 55 mol % GC and were regarded as Pseudomonas spp., two were similar to the genus AZteromonas, and one w...

This article presents the new Italian database of physical agents, which is available at http://www.portaleagentifisici.it. It supports in risk assessment employers who have to comply with Italy's Legislative Decree 81/2008 (transposing into law European Union Directives 2003/10/EC, 2002/44/EC, 2004/40/EC and 2006/25/EC). The database currently contains measurements and declared European Commun...

The Italian vibration database is presented. It is hosted by a web server at the National Institute of Occupational Prevention and Safety (ISPESL) in Rome, Italy (http: / /www.ispesl.it/vibrationdatabase). It supports in risk assessment employers who have to comply with Legislative Decree 187/05, now replaced by Legislative Decree 81/08, which transposes into law Vibration Directive 2002/44/EC....

D. Klahr, W. C. Chase, and E. Lovelace (1983) proposed a model of the cognitive processes involved in alphabetic retrieval in terms of a 2-level hierarchy of forward-linked associations. J. Seharroo, E. Leeuwenberg, P. F. M. Stalmeier, and P. G. Vos (1994) attempt to demonstrate that a simple associative model is more plausible, more parsimonious, and a better fit to the data than is Klahr et a...