Epidemic Models of Malicious-Code Propagation and Control in Wireless Sensor Networks: An Indepth Review

Wireless Personal Communications - Besides anti-malware usage for the eradication of malicious attacks, researchers have developed epidemic models in order to gain more insights into the spread...     

Life time prediction of self-supporting flame-sprayed alumina-rich coatings

Main objective of the presented research is the life time prediction of self-supporting flame-sprayed Al₂O₃- and Al₂O₃ -ZrO₂ -TiO₂-materials under constant load. The characteristic life time and its scatter were derived from stable crack growth tests and Weibull-statistics including the four-point-bending and ball-on-three-balls method. The potential life time was estimated in order to assess room-temperature handling and long term storage of self-supporting flame-sprayed alumina components. In terms of flexural strength, energy release, and subcritical crack growth parameters, distinct differences between both materials were shown. In turn, the characteristic life times only barely deviated from each other. From that the conclusion was drawn that life time performance under constant load application is governed by the characteristic flame-spray microstructure. However, advantages in the flame-spray processing of Al₂O₃ - ZrO₂ -TiO₂ are still given, attributed to its lower melting temperature.     

Assessment of the elastic moduli of cement paste and mortar phases in concrete from pulse velocity tests

This paper describes a method for estimating the elastic moduli of the cement paste, mortar and ‘coarse aggregate-paste mixture’ phases in concrete. It is concluded that the elastic moduli of these phases can be predicted without recourse to tests on neat mortar and cement paste mixes. The elastic modulus of a mortar phase in concrete can be significantly different from that of a ‘neat mortar’ having the same mix proportions. Factors such as age, mix proportions and aggregate types, influence the elastic moduli of the different phases.