Hammer

The intact rock strength of a rock mass has been determined by several different means in the context of research for slope stability assessment. The intact rock strength was determined with unconfined compressive strength testing, Schmidt hammer, Equotip, and estimation by so-called ‘simple means’. Estimation by ‘simple means’ denotes estimating the intact rock strength by hammer blows, crumbling by hand, etc. Many different people to avoid observer bias have done hundreds of assessments of intact rock strength by different means on the same rock masses. The results show that in many cases an estimation of intact rock strength by ‘simple means’ is more representative for establishing the intact rock strength of a rock mass than establishing the intact rock strength by more elaborate testing.

A hammer-string interaction for bass notes is investigated and the problem what can cause the hammer to rebound is clarified. For a linear elastic hammer interacting with a long flexible string the exact solution of the equation describing the hammer motion is derived. It was shown that in some cases no reflected wave is needed to assist the hammer for going away from the string. The numer-ical simulation carried out for the first ten hammers and strings of Parlour Grand Piano shows that the real hys-teretic hammer leave the string before the string begins pushing back on the hammer.

This article focuses on various aspects of research theory and development work concerning accidental combustion in nuclear facility and oil industry pipelines. The theory has safety implications for any pipeline where explosive gases can form in liquid-filled systems, and is consistent with pipeline accidents in nuclear power plants, such as Three Mile Island. Nuclear reactor accidents deserve further investigation, since reactor fires and explosions were ignited by sources that were reported to be unknown. The NRC documented extensive actions to improve reactor safety after the Three Mile Island accident; however, this new ignition theory has yet to be fully evaluated with respect to off-normal reactor operations in the United States and abroad. Several nuclear reactor fires and explosions warrant consideration. This new theory confirms a source of ignition. Reactor explosions can be stopped to improve nuclear reactor safety, prevent deaths, and avoid environmental disasters.

Over the last ten years, sites dated to the end of the Late Glacial, and particularly of the Belloisian have become more common in the north of France. But only a few sites yielded faunal remains, wich explains that the discovery of the Alizay attributed to the Belloisian is therefore crucial. The faunal assemblage is compose of 402 remains but only 65 could be clearly identified. Only two species were identified: aurochs (Bos primigenius) and reindeer (Rangifer tarandus). One of the most striking contributions to the knowledge on practices related to bone materials is the presence of the complete operational sequence of fracturing long bones, including the employed tools. This paper focuses on it.