In order to improve the impact performance, the structure of hydraulic hammer should be optimized. In this paper, the ranges of eight vital structure parameters of piston and reversing valve system of hydraulic hammer were selected firstly; and then found the best value of different parameters under experiments with the method of computer optimization and the parametric analysis method provided...

In a study of articles published in the Proceedings of the National Academy of Sciences, Gunther Eysenbach discovered a significant citation advantage for those articles made freely-available upon publication (Eysenbach 2006). While the author attempted to control for confounding factors that may have explained the citation differential, the study was unable to control for characteristics of th...

A concert pianist is able to produce a wide range of imaginable nuances of musical expression by actuating the 88 keys on a piano, none of which travel through a distance greater than one centimeter. In this study, we investigated the temporal behaviour of grand piano actions from different manufacturers using different types of touch (‘legato’ versus ‘staccato’). An experimental setup consisti...

pits, quarries, and on construction sites. The prediction of the penetration rate of drilling machines is very important for cost estimation and planning of rock excavation projects. Many researchers have investigated percussive drilling theoretically or experimentally and correlated the penetration rate with various rock properties. Protodyakonov (1962) developed drop tests and described the c...

Prediction of the production rate of the cutting dimensional stone process is crucial, especially when chain saw machines are used. The cutting dimensional rock process is generally a complex issue with numerous effective factors including variable and unreliable conditions of the rocks and cutting machines. The Group Method of Data Handling (GMDH) type of neural network and Radial Basis Functi...