LΩUI: Lovely ΩMEGA User Interface

The capabilities of a automated theorem prover's interface are essential for the effective use of (interactive) proof systems. LΩUI is the multi-modal interface that combines several features: a graphical display of information in a proof graph, a selective term browser with hypertext facilities, proof and proof plan presentation in natural language, and an editor for adding and maintaining the knowledge base. LΩUI is realized in an agent-based client-server architecture and implemented in the concurrent constraint programming language Oz. Received November 1998 / Accepted in revised form June 1999     

不同光束移动速度下的激光淬火有限元分析

为研究不同激光淬火处理条件下激光淬火温度场和物相结构,运用ABAQUS/Standard对激光淬火处理AISI4140钢进行了有限元模拟,并结合实验进行了验证.结果表明：激光淬火材料最高温度并不在光束中心,而是出现在距激光束中心2 mm的位置,且不随着光束移动速度的增大而改变位置;在激光束最高温度恒定为1150℃情况下...     

Effects of Fiber Orientation and Moisture on the Crack Growth in Short Glass Fiber Reinforced Polyamide

Short glass fiber reinforced polyamides are increasingly used in automotive applications. Concepts and models are needed, which enable the prediction of the structural durability. The fiber orientation and the content of moisture have a major influence on the fracture mechanical properties and on the damage mechanisms. The complex crack growth behavior was investigated and described in an empirical model.     

Combined Impact of Ultraviolet and Chemical Fluids on High‐density Polyethylene Packaging Material

To investigate the ageing behaviour of filled plastic containers outdoors, square cuts of the wall of two high‐density polyethylene (HDPE) types were exposed to ultraviolet (UV) radiation at their front side and to specific liquid chemicals (de‐ionized water, surfactant or White Spirit) at their back. The UV radiant exposure at the front side was 80 MJ/m². To compare the actions of the different exposures, separate dark backside fluid exposures were performed, in parallel. Besides, UV weathering was carried out until a UV radiant exposure of 325 MJ/m², being roughly comparable to outdoor exposure of one year in Northern Australia. An unpigmented HDPE included in the investigation gave no sufficient protection for the White Spirit. In addition, it showed clear degradation after several of these exposures. In combination with the White Spirit, an increase of carbonyl bonds was measured, presumably assignable to degradation products of the White Spirit. For a pigmented HDPE material, with the implemented combined exposures, no relevant damage was observed, within applied the exposure period. Copyright © 2011 John Wiley & Sons, Ltd.     

Performance Analysis of Dedicated Signalling Channels in GERAN by Retrial Queues

GERAN (GSM-EDGE Radio Access Network) operators have traditionally used the Erlang B formula to estimate the number of signalling channels on a per-cell basis. Thus, it is assumed that the network behaves as a loss system with Poisson arrivals. However, the presence of automatic retrial mechanisms and correlated arrivals in these channels suggests that these assumptions might not be valid. This paper presents a performance analysis of the Stand-alone Dedicated Control CHannel in GERAN. Preliminary analysis shows that the Erlang B formula underestimates congestion and blocking on this channel. To address this issue, a queueing model with retrials and correlated arrivals is proposed, where correlation between arrivals is modelled by a simple Markov-Modulated Poisson Process. The proposed model can be tuned on a per-cell basis by statistics in the Network Management System. Model assessment is based on performance statistics from a live GERAN system. Results show that a simple retrial queueing model fails to explain blocking in cells with a large number of channels. These limitations are overcome by adding correlated arrivals in the retrial model.     

Random geometric graphs for modelling the pore space of fibre-based materials

A stochastic network model is developed which describes the 3D morphology of the pore space in fibre-based materials. It has the form of a random geometric graph, where the vertex set is modelled by random point processes and the edges are put using tools from graph theory and Markov chain Monte Carlo simulation. The model parameters are fitted to real image data gained by X-ray synchrotron tomography. In particular, they are specified in such a way that the distributions of vertex degrees and edge lengths, respectively, coincide to a large extent for real and simulated data. Furthermore, the network model is used to introduce a morphology-based notion of pores and their sizes. The model is validated by considering physical characteristics which are relevant for transport processes in the pore space, like geometric tortuosity, i.e., the distribution of shortest path lengths through the material relative to its thickness.