Search results for " Structural"
showing 10 items of 1751 documents
Experimental Procedures of Accelerated Aging and Evaluation of Effectiveness of Nanostructured Products for the Protection of Volterra (Italy) Panchi…
2022
The aims of the research were to evaluate the effectiveness of the application of nanostructured products on Volterra calcarenite stone and to define the experimental conditions and procedures of accelerated aging tests, able to simulate different degradation on the studied lithotype. The work focused on methods of performing accelerated aging tests in order to simulate different effects of environmental decay involving stone used on a historical site. The rock samples were examined before and after three treatment types: cyclic salt spray chamber, cycles of freezing–thawing and cycles of thermal shock. After each artificial aging cycle, changes in appearance were noted and chemical and phy…
Non-linear analysis of plane steel prestressed truss in fire
2002
The concept of analysis of 2-D static loaded prestressed steel trusses till failure during fire using a modified method of forces is presented. Failure of steel trusses in fire is based on the criterion of stresses. Behaviour of steel is described by non-linear constitutive model (based on hypo-elastic Ramberg-Osgood formula and Dorn creep theory) and Plem proposition (for string). Both models are approximated in calculations by hyperbolic Norton-Bailey rule. Fire simulates thermal force as an action of high temperature that increases linearly up to some level. The complete formulation of this method is illustrated by the algorithm of model parameters identification. Analysis of results for…
Intra‐individual dynamics of lesson‐specific engagement: Lagged and cross‐lagged effects from one lesson to the next
2020
Background Student engagement denotes active participation in academic work through commitment and involvement in learning tasks (Appleton et al., 2006, Journal of School Psychology, 44, 427). This study looks at questions such as whether engagement experiences in one lesson have an effect on the next lesson. In the present study, process‐oriented analyses were conducted to examine lower secondary school students’ engagement experiences and the stability of those experiences from one lesson to the next. Aims (1) To what extent are students’ engagement experiences, in terms of behavioural and cognitive engagement, emotional engagement, and disaffection, stable from one lesson to the next (au…
Estimating the safety performance function for urban unsignalized four-legged one-way intersections in Palermo, Italy
2014
Abstract Starting from consideration that urban intersections are sites with promise for safety and operational improvements, the paper describes the steps taken to develop a crash predictive model for estimating the safety performance of urban unsignalized intersections located in Palermo, Italy. The focus is on unsignalized four-legged one-way intersections widespread in Italian downtowns. The sample considered in the study consist of 92 intersections in Palermo, Italy. For the study were collected crashes occurred in the sites during the years 2006-2012, geometric design and functional characteristics and traffic flow. Results showed that data were overdispersed and NB1 distributed. In o…
The parental bond, resistance to peer influence and risky driving in adolescence
2014
The present study examined the relations between gender, the parental bond, resistance to peer influence, and risky driving. In particular, the mediating role of resistance to peer pressure in the relationship between parental bond and risky driving was examined. The moderating role of gender on these associations was also investigated. The sample comprised 322 adolescents (136 males and 186 females), aged from 16 to 20 years, who were living in northern Italy. Path analysis results showed that the maternal bond only indirectly influenced adolescents’ risky driving, via resistance to peer influence. On the contrary, the paternal bond was neither directly nor indirectly associated with risky…
Structural Parameters under Partial Least Squares and Covariance-Based Structural Equation Modeling : A Comment on Yuan and Deng (2021)
2023
In their article, Yuan and Deng argue that a structural parameter under partial least squares structural equation modeling (PLS-SEM) is zero if and only if the same structural parameter is zero under covariance-based structural equation modeling (CB-SEM). Yuan and Deng then conclude that statistical tests on individual structural parameters assessing the null hypothesis of no effect can achieve the same purpose in CB-SEM and PLS-SEM. Our response to their article highlights that the relationship they find between PLS-SEM and CB-SEM structural parameters is not universally valid, and that consequently, tests on individual parameters in CB-SEM and PLS-SEM generally do not fulfill the same pur…
On the use of the EMI for the health monitoring of bonded elements
2014
The low weight, robustness and fatigue resistance of adhesive joints make them suitable for structural joints. A fully developed nondestructive evaluation technique however is needed to monitor and assess the quality of bonded joints. In the present paper the application of the electromechanical impedance (EMI) technique is proposed. In the EMI method a piezoelectric transducer (PZT) is attached to the structure of interest. The high sensitivity and low power consumption make the EMI method feasible for real time structural health monitoring. In this study we investigated the sensitivity of the electromechanical response of a PZT to the curing and the quality of the adhesive used for bonded…
Analysis of FBG reflection spectra under uniform and non-uniform transverse loads
2019
Loads applied transversely on the external surface of waveguides change their circular cross-sectional geometry generating birefringence. Due to this effect the reflected spectrum of a Fibre Bragg grating (FBG) undergoes a splitting of the single peak of the Bragg wavelength. In this work, we employed the Transfer Matrix Method (TMM) for x- and y-polarized wave-modes to model the uniform FBG reflection spectra for uniform and non-uniform transverse loads. We also performed experimental measurements for two different transverse load scenarios. The load profiles chosen for these experiments were applied on the FBG sensor through a block of steel and a roll bearing pin. Then, the modelled and …
RILEM TC 279 WMR round robin study on waste polyethylene modified bituminous binders: advantages and challenges
2022
inter-laboratory experiments were designed to evaluate the impact of plas- tic waste blended directly in bitumen and to assess the properties, using conventional and advanced bituminous binder testing. The blends tar- geted 5% of plastic waste in 95% bitumen, using two types of polyethy- lene (PE) primary (pellets) and secondary (shreds) waste. The experiments showed that the addition of PE waste to bitumen does not alter the chem- istry of the bitumen, the blending is physical. The DSR results indicate a strong dependency on the testing temperature as at low temperatures the composite material bitumen and PE behave both elastically whereas, at higher temperatures, the bitumen becomes visco…
Weathering of low-density polyethylene grafted with itaconic acid in laboratory tests
2011
Polyethylene grafted with itaconic acid was subjected to weathering under laboratory accelerated conditions. The course of the photo-oxidative degradation process of that material was studied by FTIR spectroscopy both through quantitative measurements of changes in absorbance values at selected wave numbers and through measurements of surface area values for absorption bands which were separated by means of deconvolution. The use of both those procedures of quantitative determinations resulted in a general conclusion that the oxidation process was initiated from the very first moment of irradiation, and it produced ketones, acids, esters (intramolecular and of acetate type), peracids, peres…