添加碳纳米管对选区激光熔化AlSi10Mg合金缺陷的影响

利用选区激光熔化成形技术制备了纯AlSi10Mg合金及碳纳米管(carbon nanotubes,CNTs)-AlSi10Mg复合材料。当添加CNTs含量为0.05%(质量分数)时具有一定增强效果,但随着CNTs添加量增大,复合材料性能却因为缺陷的增加而明显下降。木实验利用纳米CT技术对纯合金及CNTs(0.5%)-AlSi10Mg复合材料进行缺陷的三维重构。结果表明,添加0.5%的CNTs后,成形缺陷体积所占比例由12%增加至46%;气孔型缺陷数量明显增加,并且等效直径相对较大。CNTs在粉体中的团聚及对气体的吸附作用是两种类型缺陷增加的根本原因。     

Assessment and evaluation of the radiological situation in the late phase of a nuclear accident

An overview of existing approaches on assessing and evaluating the radiological situation in the late phase of a nuclear accident is given in this paper. Special attention is paid to the weak points of existing approaches and to problems to be solved in the future. Assessment of the radiological situation can be based on both monitoring data and model predictions. Approaches have been developed for many years in both categories and have meanwhile reached some kind of maturity and also operational applicability. Nevertheless, some areas exist where significant improvements could be achieved in the near future, e.g. by combining monitoring data and model predictions, by improving the modelling of urban areas or by improving existing radioecological models.     

A Formal Proof of Sylow's Theorem

The theorem of Sylow is proved in Isabelle HOL. We follow the proof by Wielandt that is more general than the original and uses a nontrivial combinatorial identity. The mathematical proof is explained in some detail, leading on to the mechanization of group theory and the necessary combinatorics in Isabelle. We present the mechanization of the proof in detail, giving reference to theorems contained in an appendix. Some weak points of the experiment with respect to a natural treatment of abstract algebraic reasoning give rise to a discussion of the use of module systems to represent abstract algebra in theorem provers. Drawing from that, we present tentative ideas for further research into a section concept for Isabelle.     

Safety Certificate: an audification performance of high-speed trains

Safety Certificate is a musical performance based on sensor data from high-speed trains. The original purpose of this data is to provide a basis for the assessments of the mechanical aspects of train safety. In this performance, the data, which represents dynamical processes below the audible range, are converted into sound through audification. The sound that is generated live during the performance is manipulated through the Manta control interface, which allows for the convenient layering of 48 different timbres. Safety Certificate was premiered at Seconde Nature in Aix-en-Provence in March 2010 during the Sonification symposium–What, Where, How, Why, organized by Locus Sonus. The following short article gives details about the data, the audification technique, use of the control interface, and the musical structure of the performance.     

Das Dekompositionsmodell nach Wand und Weber im Kontext der Prozessmodellierung

Whereas the benefits of decomposing process models are obvious, the question what actually characterizes a ??good?? decomposition of a business process model has been given little attention to date. In addition, the process of decomposition itself is considered as being an ??art?? in literature. Our approach for achieving a ??good?? decomposition is Wand and Weber??s decomposition model for information systems. As a first step in our investigation we aim to explore in how far the decomposition model can be adapted for business process modelling at all. The potential this model might bear for evaluating decompositions of process models has been promoted in literature quite often, while a corresponding investigation is still missing. We address this gap by the following research. In the long term, we intend to establish guidelines for decomposing business process models in a structured way.     

Calibration and validation of a solar thermal system model in Modelica

Recent advancements in the domain of modeling physical processes offer opportunities to use equation based modeling environments, such as Modelica, for the simulation of building heating, ventilation, and air-conditioning (HVAC) systems. The current work demonstrates Modelica capabilities in a case study of real building solar thermal system simulation. The simulated system is part of an innovative ENERGYbase building, designed according to the so called Passivhaus standard. Model calibration and validation procedure is developed to include optimization based parametric adjustments of component models using the monitoring data during a single week. The calibrated system adequately reproduces half a year of real system operation. Future work will concentrate on application of the developed calibration and validation methodology in the whole year overall building energy simulation.