Geotechnical Structures in the Ancient World. The Case of the Ziggurat of Ur in Mesopotamia

The current study presents several geotechnical structures which were built during the antiquity, aiming to illustrate the ancient technological achievements and to provide an insight into the geotechnical skills in the past. It is evident that ancient civilizations had awareness of the various geological and climatological / meteorological hazards (i.e. natural hazards) that affected the structures and used rather reliable techniques for that time. Furthermore, the study aims to illustrate how some of these are related to modern geotechnical structures. More specifically, the earth retaining techniques used for the construction of the massive pyramid-like structures Ziggurats are shown, highlighting their contribution to structural safety. In this framework, several numerical models have been built and analysed, using the Bishop Analysis for slope stability method and the Finite Element Stress Analysis Method. The results of the numerical simulations are presented and discussed

Quantification of the Structural Response of Historical Constructions: Investigation of the Strain Variation at the Acropolis Circuit Wall

The current study aims to assist the preservation of the structural integrity of historical complex sites, utilizing smart instrumental monitoring / remote sensing. The main idea is that smart instrumental monitoring can provide important real-time information (records) of both the actual natural hazard(s) and the corresponding vulnerability, in terms of structural response and distress of structures and monuments of historically complex sites. The study focuses on the Acropolis Circuit Wall, where strain recordings via Smart Rod optical fibre sensors have been made possible. More specifically, wavelength recordings have been obtained and then converted into strain recordings, while the temperature influence has been taken into consideration. Furthermore, reference measurements have been defined during the initial system operation and then they are used for deduction of subsequent recordings. Strains recorded 2 and 1/2years after the initial system installation are shown, after the deduction of the reference measurements. Finally, strain variation between sensors located at the inner and outer side of the same optical fibre Smart Rod are shown

Nanostructured titania films sensitized by quantum dot chalcogenides

The optical and structural properties of cadmium and lead sulfide nanocrystals deposited on mesoporous TiO(2 )substrates via the successive ionic layer adsorption and reaction method were comparatively investigated by reflectance, transmittance, micro-Raman and photoluminescence measurements. Enhanced interfacial electron transfer is evidenced upon direct growth of both CdS and PbS on TiO(2 )through the marked quenching of their excitonic emission. The optical absorbance of CdS/TiO(2 )can be tuned over a narrow spectral range. On the other side PbS/TiO(2 )exhibits a remarkable band gap tunability extending from the visible to the near infrared range, due to the distinct quantum size effects of PbS quantum dots. However, PbS/TiO(2 )suffers from severe degradation upon air exposure. Degradation effects are much less pronounced for CdS/TiO(2 )that is appreciably more stable, though it degrades readily upon visible light illumination