繋がらなかった歴史 : 第2次世界大戦と再形成するインドネシア史

早大学位記番号:新7306早稲田大

Ultrahigh-temperature osumilite gneisses in southern Madagascar record combined heat advection and high rates of radiogenic heat production in a long-lived high-T orogen

We report the discovery of osumilite in ultrahigh‐temperature (UHT) metapelites of the Anosyen domain, southern Madagascar. The gneisses equilibrated at ~930°C/0.6 GPa. Monazite and zircon U–Pb dates record 80 Ma of metamorphism. Monazite compositional trends reflect the transition from prograde to retrograde metamorphism at 550 Ma. Eu anomalies in monazite reflect changes in fO_2 relative to quartz–fayalite–magnetite related to the growth and breakdown of spinel. The ratio Gd/Yb in monazite records the growth and breakdown of garnet. High rates of radiogenic heat production were the primary control on metamorphic grade at the regional scale. The short duration of prograde metamorphism in the osumilite gneisses (<29 ± 8 Ma) suggests that a thin mantle lithosphere (<80 km) or advective heating may have also been important in the formation of this high‐T, low‐P terrane

Dragline Field Testing

Draglines are the most expensive pieces of equipment used in coal mines at a cost of $50 M to$100M each. Improving their productivity will produce major benefits to the coal mining industry. The dynamic behaviour of the dragline structure has a significant effect on the fatigue life of the main components of a dragline and related maintenance costs. This paper describes the field tests conducted on the dragline DRE23 at the Peak Down coal mine, Queensland, Australia. Sixteen accelerometers were installed on the dragline boom and mast. Three different excitation methods were used in the test: 5.4-kg impact hammer, dragline bucket impulse and ambient excitations produced during normal operation. The aim of the modal testing was set to explore the six global modes for the dragline boom structure. The results showed that the impact hammer excitation was not adequate to excite any of the global modes. The excitation produced by bucket impulse was powerful but was difficult to control. The output-only identification using the response to the ambient excitation was promising but it was difficult to identify all targeted global modes

A fluid analysis framework for a Markovian process algebra

Markovian process algebras, such as PEPA and stochastic π-calculus, bring a powerful compositional approach to the performance modelling of complex systems. However, the models generated by process algebras, as with other interleaving formalisms, are susceptible to the state space explosion problem. Models with only a modest number of process algebra terms can easily generate so many states that they are all but intractable to traditional solution techniques. Previous work aimed at addressing this problem has presented a fluid-flow approximation allowing the analysis of systems which would otherwise be inaccessible. To achieve this, systems of ordinary differential equations describing the fluid flow of the stochastic process algebra model are generated informally. In this paper, we show formally that for a large class of models, this fluid-flow analysis can be directly derived from the stochastic process algebra model as an approximation to the mean number of component types within the model. The nature of the fluid approximation is derived and characterised by direct comparison with the Chapman–Kolmogorov equations underlying the Markov model. Furthermore, we compare the fluid approximation with the exact solution using stochastic simulation and we are able to demonstrate that it is a very accurate approximation in many cases. For the first time, we also show how to extend these techniques naturally to generate systems of differential equations approximating higher order moments of model component counts. These are important performance characteristics for estimating, for instance, the variance of the component counts. This is very necessary if we are to understand how precise the fluid-flow calculation is, in a given modelling situation