Theophanes and Mytilene's Freedom reconsidered: A postscript

No Abstract

Theophanes and Mytilene's Freedom reconsidered

No Abstract

Theophanes and Mytilene's Freedom reconsidered: A postscript

No Abstract

Theophanes and Mytilene's Freedom reconsidered

No Abstract

Networked Learning Physics of Semiconductors through a Virtual Laboratory Environment

This poster is part of the Symposium organised by Demosthenes Stamatis and Theodoros Kargidis Virtual laboratory tools have been introduced a long time ago. Such tools have been used into the learning procedure in order to help students to increase their performance through a user friendly tool that stimulates them on their study. Additionally, when the high cost of hardware replacement and maintenance is put in contrast to the flexibility of adding new subjects on a laboratory course the virtual laboratory environment tools render a power tool for educational purposes. Statistics show that students do not spend adequate time preparing for an upcoming laboratory module, thus new methodologies and software have recently been developed and offered to students in order to increase their performance in laboratory modules. In this work a virtual laboratory environment that was built is described, discussed and evaluated. The software deals with the laboratory assignments of Semiconductor Physics. Semiconductor Physics was chosen since it is a first year module that is not connected to any background knowledge the students should be familiar with. The evaluation was made by providing the software to some of the students and comparing their performance with the corresponding performance of the students that had no access to the software. It is concluded that the software tool that was provided to the students before taking the laboratory increased their performance. It was also observed that this tool mainly serves weaker students since, according to the evaluation tests, they are mainly helped to achieve a pass score

Piezo stimulated currents in marble samples: precursory and concurrent-with-failure signals

International audienceThe Earth?s electric field transient variations are promising candidates of earthquake precursors. In order to study the physical mechanisms of such precursory signals, laboratory experiments of uniaxial compression were carried out. More specifically the behaviour of stressed marble samples from Penteli Mountain was investigated. The samples were subjected to a time-varying uniaxial compression at both variable and constant stress rates. During the first set of experiments weak electric currents were detected during pressure variations. Such Piezo Stimulated Currents (PSC) were detected while stress steps, both positive and negative were applied, the maximum stress never being greater than the elasticity limit. During the second set of experiments stress was applied at a constant rate starting from zero-stress and ending in fracture. In the region beyond the elastic limit a PSC was detected which after reaching a peak suffered a reversal in its polarity just before fracture. In a third set of experiments the same procedure was applied to previously structurally damaged samples taking care not to fracture them. In all cases the PSC followed the variation of stress and moreover it was observed that a linear relationship existed between the PSC maxima and the corresponding stress-rate maxima. The mechanism responsible for the described phenomena can be ascribed to the Moving Charged Dislocations model

Correlation of pressure stimulated currents in rocks with the damage parameter

Pressure Stimulated Current (PSC) experiments were conducted on marble samples to correlate PSC with the damage parameter, D. The phenomena and procedures taking place in the vicinity of the fracture limit were observed and analytically described. PSC recordings were conducted by application of uniaxial compressional stress, both at a constant stress rate and at a constant deformation rate. A linear relationship was shown to exist between the emitted PSC and the damage parameter which quantifies the deviation from linear elasticity and the concentration of microcracks

Controlling the reversible wetting capability of smart photochromic-polymer surfaces by micro patterning

We demonstrate the wetting behavior control of polymer surfaces doped with photochromic molecules by modifying the surface patterning features introduced by soft molding lithography. Such surfaces enhance their hydrophilicity upon UV irradiation due to conversion of the non-polar spiropyran dopant molecules to their polar merocyanine isomers. The process is reversed upon visible light irradiation. By changing the topological parameters of the introduced pattern, one achieves surface tuning from hydrophobic to hydrophilic situations. The difference for the contact angles between UV- and green-irradiated surfaces may become significantly higher than for the flat surfaces, for the specific patterning parameters analyzed

Pressure Stimulated Currents (PSC)in marble samples

The electrical behaviour of marble samples from Penteli Mountain was studied while they were subjected to uniaxial stress. The application of consecutive impulsive variations of uniaxial stress to thirty connatural samples produced Pressure Stimulated Currents (PSC). The linear relationship between the recorded PSC and the applied variation rate was investigated. The main results are the following: as far as the samples were under pressure corresponding to their elastic region, the maximum PSC value obeyed a linear law with respect to pressure variation. In the plastic region deviations were observed which were due to variations of Young s modulus. Furthermore, a special burst form of PSC recordings during failure is presented. The latter is emitted when irregular longitudinal splitting is observed during failure