Search results for "technical"
showing 10 items of 955 documents
Experimental Evidence of Leaks in Elastic Pipes
2016
Several studies have been carried out in recent decades to establish a relationship between total head and leaks. In literature, the leakage governing equations have been analysed in light of pipe materials, water head, leak dimension or shape. Most of these contributions questioned the classical Torricelli equation, demonstrating through experimental evidence that the classical orifice law can give unsatisfactory results. Nevertheless, starting from the Torricelli equation, other exponential or linear governing equations have been proposed as mathematical models able to reproduce the leakages in water distribution systems (WDSs). To investigate the validity of the proposed governing equati…
Fabric evolution and the related swelling behaviour of a sand/bentonite mixture upon hydro-chemo-mechanical loadings
2015
This experimental study investigates the swelling behaviour of an 80/20 sand/bentonite mixture and the associated fabric evolution under different hydro-chemo-mechanical loadings. Free and confined swelling tests are performed on specimens compacted to different dry densities and wetted with different pore fluids. Controlled suction confined swelling tests are performed to determine the suction–swelling pressure relationship for two different densities. An extensive microstructural characterisation is performed to relate the observed swelling behaviour to the evolution of the different pore networks during wetting. Based on the microstructural analysis, an expression is proposed to determi…
An experimental and constitutive investigation on the chemo-mechanical behaviour of a clay
2013
Engineering issues for which the understanding of the chemo-mechanical behaviour of soils is relevant include wellbore stability problems, the salinification of groundwater, and nuclear waste storage. However, despite the vast number of situations in which couplings between chemistry and mechanics occur, the available constitutive models rely on limited experimental evidence. This paper presents the results of an experimental programme on the chemo-mechanical behaviour of a non-swelling illite. The osmotic suction is controlled through the ion concentration of sodium chloride in the pore water. Stress paths include mechanical loading at a constant osmotic suction, and an increasing osmotic …
Hydromechanical behaviour of a volcanic ash
2013
This paper presents experimental analysis and numerical modelling aimed at improved understanding and prediction of the hydromechanical behaviour of volcanic ash at various states of saturation. Results from a comprehensive experimental programme are presented in order to characterise the response of the material in terms of matric suction and confining stress changes. The evolution of the yield stress at different suction levels has been quantified. The volumetric response with suction variations allowed the analysis of the collapse-upon-wetting behaviour. Water retention and permeability are also addressed. Tests results are used to calibrate a constitutive model based on the effective s…
Italian multicentric survey on laparoscopic spleen surgery in the pediatric population.
2007
Abstract Background: Some technical aspects of laparoscopic spleen surgery still are debated, although efforts have been made to standardize them. The position of the patient, the approach to the spleen, vessel identification and division, and spleen extraction can vary from center to center. Methods: This retrospective muticentric study led by the Societa` Italiana di Videochirurgia Infantile (SIVI) examined indications, surgical details, and complications of laparoscopic spleen surgery in the pediatric population during a 5-year period. Results: The study period from January 1999 to December 2003 (5 years) involved nine centers and included 85 patients with a mean age of 10 years (range, …
Measure of a limestone weathering degree using Laser Scanner.
2013
The weathering degree of the building materials and natural stones is generally quantified as the decrement of some mechanical features that can be measured experimentally by means of compressive tests or point load tests in the laboratory or Schmidt hammer tests carried out in situ. Such destructive or damaging tests are unacceptable in case of cultural heritage since even small amounts of damage must be avoided. This work shows a correlation between Schmidt hammer rebound values and the reflectivity that is detected by means of terrestrial scanner laser; therefore it allows assessing the weathering degree of buildings or stones in situ. The results demonstrate that such an investigation c…
The Latomiae of Syracuse: A Geotechnical Mapping Through Rock Reflectivity
2014
The archeological site of the Latomia del Paradiso (Syracuse) is endangered by severe instability phenomena due to the shape of walls and underground excava-tion related with the poor mechanical characteristics of the weathered and wet rock. The failure of huge blocks from the ceiling of the underground areas and the detaching of rock "flakes" from the walls surface make the geotechnical zon-ing particularly complex. the zoning is based on the characteristics of the rock wall surface that, in first approximation, can be distinguished in regularized sur-faces because of mining , and in irregular surfaces characterized by fracture prop-agation. The elaboration of reflectivity values obtained …
Rock decay phenomena and collapse processes in the “Latomiae del Paradiso” in Syracuse (Sicily)
2014
The Latomiae (origin: Greek latomia, from laas, las stone plus –tomia tomy ) del Paradiso in Syracuse are Magna Graecia rock quarries, located in the coastal areas of Southern Italy and internationally renowned for their impressive environment. The few historical technical records do not help clarify the events that led to their current configuration since a series of instability phenomena occurred due to decay processes over time. Through a geotechnical back-analysis, this work highlights the failure phenomena, which may have led to the current configuration of the easterly side of the Latomiae del Paradiso. The back-analysis process was carried out by means of numerical modelling, support…
Astronomiskajam tornim - 150
2019
Astronomiskais tornis uz Latvijas Universitātes galvenās ēkas jumta jau 150 gadus kalpo kā logs uz kosmosu. 19. gadsimtā te veikti zinātniski novērojumi, 20. gadsimtā tornī uzstādīto Heides teleskopu izmantoja studentu apmācībai un debess spīdekļu demonstrēšanai. No 1986. gada zvaigžņotās debess demonstrējumi notiek ļoti aktīvi, nomainījušies trīs teleskopi.
Die landwirtschaftliche Abteilung am Polytechnischen Institut zu Riga in der ersten 50 Jahren ihres Bestehens (1862-1912)
1915
Inhalt: I. Historischer Überblick ...1 II. Organisation des landwirtschaftlichen Unterrichte. Mit Tabelle I... 16 III. Die landwirtschaftliche Lehr- und Versuchsfarm Peterhof... 26 IV. Personalien... 41 V. Zahl der Studierenden und Absolventen. Mit Tabelle II... 56