Side milling capability of rock cutting tools
Currently, the deviating hole drilling occupies a leading role in Russia. Directional drilling is used when the wells for oil and gas in Western Siberia, in the north of the European part, in the North Caucasus, in Tatarstan, Bashkortostan, Samara region and other areas are drilled, as our regions have a vast number of factors interfering with conventional drilling.
An investigation into autobalancing devices with multireservoir system
Behaviour of a liquid-type automatic balancing device is modeled in this paper. To perform mathematical research the authors use a rotor model which contains a ring functioning as a reservoir coupled to a rigid shaft being rotatable in bearings. An autobalancer with several reservoirs is used for the mathematical investigation. The article provides the layout of forces acting in a multi-reservoir balancing system. Data on the effect of various factors on balancing accuracy as well as the main calculation features of a multi-reservoir autobalancer are presented. The obtained modeling results indicate that autobalancing efficiency is enhanced by increasing the number of reservoirs. An increase in the number of reservoirs causes a decrease in a critical rotor speed.
Time and Heritage
As a historian studying what can be considered a form of intellectual history, I have slowly come to adopt Michel de Certeau’s observation made at the end of the 1980s that ‘objectifying the past, for the last three centuries, has undoubtedly left unconsidered time within a discipline that has continued to use it as a taxonomic instrument’. To a certain degree, time has become commonplace for the historian who has preserved or instrumentalized it. It is not considered because it is inconceivable, but because we do not think of it or, more simply, we do not think about it. As a historian attempting to pay attention to the time I’m living in, I have thus, like many others, noticed the swift development of the category of the present until it has become obvious that the present is omnipresent. This is what I refer to here as ‘presentism’.