Search results for "Measurement"
showing 10 items of 2918 documents
Electro-optical characterization of new classes of Silicon Carbide UV photodetectors
2014
In this paper, we present the fabrication process steps and the characterization of 4H-SiC vertical Schottky UV detectors, where interdigitated strips, acting as top metal contacts, have been realized in $\hbox{Ni}_{2}\hbox{Si}$ . These devices exploit the pinch-off surface effect. $I$ – $V$ and $C$ – $V$ characteristics, as functions of temperature, were measured in dark conditions. In addition, we have carried out responsivity measurements, for wavelengths ranging from 200 to 400 nm, at varying package temperature and applied reverse bias. A comparison among devices having different strip pitch sizes has been performed, thus finding out that the 10- $\mu\hbox{m}$ pitch class demonstrates …
EXPERIMENTAL INVESTIGATION OF DILUTE SOLID-LIQUID SUSPENSION IN AN UNBAFFLED STIRRED VESSELS BY A NOVEL PULSED LASER BASED IMAGE ANALYSIS TECHNIQUE
2009
The availability of experimental information on solid distribution inside stirred tanks is a topic of great importance in several industrial applications. The measurement of solid particle distribution in turbulent multiphase flow is not simple and the development of suitable measurement techniques is still in progress. In this work a novel non-intrusive technique for measuring particle concentration fields in solid-liquid systems is employed. The technique makes use of a laser sheet, a high sensitivity digital camera for image acquisition and a Matlab procedure for post-processing the acquired images. Experimental data are here obtained for the case of an unbaffled stirred tank. Stable tor…
Electrodeposition and characterization of Mo oxide nanostructures
2015
Template electrodeposition has been used to grow uniform arrays of molybdenum oxide nanostructures in polycarbonate membrane. Several parameters have been investigated, like electrodeposition, time and solution pH. These parameters do not influence the nature of the deposit that always consists of mixed valence molybdenum oxides, whereas the nanostructure morphology changes with pH. In particular, at low pH (2.7), nanotubes are formed, whilst arrays of nanowires are obtained above pH 5.5. This change of morphology is likely due to H2 bubbles evolution during the electrochemical deposition, particularly occurring at low pH. It was found that fast removal of H2 bubbles through vigorous stirri…
A physical model for the interaction between unsaturated soils and retaining structures
2020
Temporary and permanent retaining structures interact with soils that are usually in unsaturated conditions. In this work, a 1g-scale physical model is presented to investigate the interactions between retaining walls and unsaturated soils. The physical model is equipped with a water-filled hydraulic cylinder connected to a pressure-volume controller to measure the horizontal component of the later earth thrust and high capacity tensiometers to measure soil matric suction. A system of low-friction linear guideways has been installed at the base of the wall-model. The failure surface is observed through a 3 cm thick glass wall on one side of the container. A series of images are acquired dur…
Discharge estimation combining flow routing and occasional measurements of velocity
2011
A new procedure is proposed for estimating river discharge hydrographs during flood events, using only water level data at a single gauged site, as well as 1-D shallow water modelling and occasional maximum surface flow velocity measurements. One-dimensional diffusive hydraulic model is used for routing the recorded stage hydrograph in the channel reach considering zero-diffusion downstream boundary condition. Based on synthetic tests concerning a broad prismatic channel, the “suitable” reach length is chosen in order to minimize the effect of the approximated downstream boundary condition on the estimation of the upstream discharge hydrograph. The Manning’s roughness coefficient is calibra…
Hydro-mechanical behaviour of a sandy silt from a river embankment
2020
The paper presents the results of an experimental campaign aimed at characterizing the hydro-mechanical behaviour of a sandy silt from a river embankment. Due to continuous river level fluctuations and changing climatic and environmental conditions, flood embankment materials experience frequent variations in degree of saturation and suction values. Such variations strongly impact the earthwork performance both in terms of seepage and stability conditions. For these reasons, a detailed characterization of the material behaviour in unsaturated conditions was carried out. Experiments were designed in order to highlight the response of the involved soil in terms of changes in matric suction an…
The Role of Capital Accumulation in the Evolution of Total Factor Productivity in Spain
2017
GDP growth in Spain was strong for much of the last half century, whereas the country’s productivity performance during these years has been mediocre. The reasons for this situation have frequently been analysed with the focus on labour productivity. But, as this article highlights, the evolution of capital productivity should also be taken into account when looking for explanations for poor productivity performance. This article analyses the sources of growth in the Spanish economy, in comparison with major economies, and takes into account the effects that the improvements in the measurement of inputs (labour and capital) have on TFP estimates. Once problems are identified and the role pl…
Estudio piloto de la validez convergente de la adaptación española del Denison Organizational Culture Survey (A pilot study of the convergent validit…
2016
The Denison Organizational Culture Survey (DOCS) is one of the most used instruments in the study of organizational culture. The aim of this study was to evaluate the convergent validity of the Spanish version of the DOCS using the Organizational Culture Inventory (OCI) developed by Cooke and Lafferty. This instrument is the most widely used and researched tool in the field of organizational psychology. The convergent validity of these instruments was evaluated using Pearson’s correlation analysis. The sample comprised 344 members from different research groups of a Spanish university. A poor correlation was found between the DOCS and the aggressive-defensive culture dimension of the OCI. H…
VALIDITY AND RELIABILITY OF MEASUREMENTS OF THE PARAMETERS OF SMILE AESTHETICS: A COMPARISON BETWEEN DIGITAL AND PLASTER MODELS
2020
This study aims to evaluate the validity and reliability of the TRIOS3 Color intraoral scanner (3Shape A/S, Copenhagen, Denmark) and its associated Ortho Analyzer™ software in measuring parameters of smile aesthetics compared with measurements on plaster casts. The study sample comprised plaster casts and digital models obtained from 30 subjects. Height (H), mesiodistal diameter (MDD) and connecting space (CS) of the anterior teeth were measured with a digital calliper on the plaster models and with the orthodontic software on the digital models. Validity was assessed using a 2-tailed paired t-test; the reliability of measurements for intra-examiner was evaluated with the Intra-class Correl…
The measurement invariance of Job Diagnostic Survey (JDS) across three university student groups
2016
Purpose: The main purpose of this study is to apply a multigroup confirmatory analysis to examine the measurement invariance (MI) of the adapted version of the Job Diagnosis Survey (JDS) as a measurement tool that analyses the relationship between the features of teaching methodologies with university students’ motivation and satisfaction across data collected on different degrees and academic years. Design/methodology/approach: Confirmatory factor analysis was carried out using a multigroup structural equation model, using the program EQS 6.1 to test the invariance of the adapted version of JDS in a sample constituted by 535 student of a Spanish public university. The assessment of invaria…