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Wave Characteristics (wave + characteristic)

Distribution by Scientific Domains

Chemistry	75%

Selected Abstracts

Detonation and Blast Wave Characteristics of Nitromethane Mixed with Particles of an Aluminium,Magnesium Alloy

PROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 2 2010
Waldemar
Abstract Investigation of detonation parameters, blast wave characteristics and quasi-static pressures (QSPs) for the mixtures of nitromethane and particles of an aluminium and magnesium (Al3Mg4) alloy was carried out. The mixtures of gelled nitromethane containing 15,60,wt.-% AlMg alloy were tested. Detonation velocity and Gurney energy were determined. Parameters of blast waves produced by charges of the investigated explosives were measured. QSP measurements were conducted in a steel chamber of 0.15,m3 volume filled with air. Thermochemical and gasdynamical calculations were also performed. The degree of combustion of the metallic addition with the gaseous products during detonation and expansion is discussed. [source]

Temporal fluctuations in heat waves at Prague,Klementinum, the Czech Republic, from 1901,97, and their relationships to atmospheric circulation

INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 1 2002
Jan Kyselý
Abstract Temporal fluctuations in heat wave occurrence and severity are analysed in long-term daily temperature series at Prague,Klementinum, the Czech Republic. Although the observations have been continuous since 1775, the period 1901,97 with the most credible data is mainly examined. Most of the warmest summers of the 20th century appeared within the periods 1943,52 and 1992,95; the temporal distribution of heat waves corresponds to this pattern and shows two maxima, in the 1940s to early 1950s and in the 1990s. A very low occurrence of heat waves was typical of the beginning of the 20th century and around 1980. The peak of heat wave severity in the 1940s,early 1950s, as well as their almost total absence in the first two decades of the 20th century, may be a common feature for a large area, as indicated by the comparison between two stations within central Europe, Prague,Klementinum and Basel (Switzerland), and by other studies. An extraordinary heat wave occurred in July and August 1994. It greatly exceeded other heat waves, mainly in the much higher cumulative temperature excess above 30°C and a record-breaking duration of a continuous period of tropical days. Relationships between heat wave characteristics in warm and cold decades and circulation conditions were analysed using the subjective Hess,Brezowsky catalogue of weather types (Grosswetterlagen). The link to the atmospheric circulation is evident, e.g. situations with an anticyclone or a ridge over central Europe were more (less) frequent during all the warm (cold) decades. Moreover, the occurrence of long and severe heat waves in the 1990s may reflect an enhanced persistence of the atmospheric circulation over Europe in the summer season because all groups of weather types have considerably increased residence times in 1988,97 compared with long-term means. Copyright © 2002 Royal Meteorological Society [source]

Large wave characteristics and their downstream evolution at high Reynolds number falling films

AICHE JOURNAL, Issue 1 2010
Margaritis Kostoglou
Abstract There are many open questions regarding the evolution of waves, especially for the case of turbulent films. To resolve the complexity in modeling wavy turbulent films, more information needs to be derived from experimental data. On this account, a new way is proposed herein to analyze experimental film thickness traces, replacing the usual statistical analysis. Large waves are identified in experimental traces, and their shape is described by approximation with a few parameters curve. The probability density functions of these parameters are identified and the whole procedure can be considered as a compression method of the information content of experimental data series. By comparing results at several downstream locations, information on the evolution of waves along the flow is derived. This information indicates a 3D character of the flow, customary neglected in modeling efforts. In addition, the current results can be used for the numerical reconstruction of experimental film thickness traces. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]