Search results for "Testing"
showing 10 items of 1769 documents
Numerical study for a new methodology of flaws detection in train axles
2013
Train loads and travel speeds have increased over time, requiring more efficient non-destructive inspection methods. Railway axles are critical elements; despite being designed to last more than 20 years several cases of premature failure have been recorded. Train axles are inspected regularly, but the limits associated to the traditional inspection technologies create a growing interest towards new solutions. Here a novel non-destructive inspection method of in-service axles based on non-contact data collection is presented. The propagation of surface waves, generated by a thermo-elastic laser source, is investigated using a finite element method based on dynamic explicit integration. Coup…
Convergence in car prices among European countries
2011
This article contributes to the literature on price convergence in Europe by investigating the existence of stochastic and deterministic convergence of car prices in the EU15 countries. We apply recently developed econometric techniques that allow for multiple structural breaks to an up-to-date dataset. We find considerable evidence of both types of convergence in our sample of countries and car models, therefore suggesting a tendency for relative prices to equalize over time. In addition, we find evidence regarding the importance in this convergence process of both legislative changes taking place in the years 1996 and 2002, and the implementation of Economic and Monetary Union (EMU).
The value drivers of high-tech consumer products
2011
Abstract This study investigates the influence of the customer-value hierarchy model and social network on the perceived economic value of high-tech consumer products. This quantitative empirical study was conducted among Finnish households in early 2008 using the form interview method. The non-probability quota sampling method was applied. The data consisted of 453 completed questionnaires. Hypothesis testing was conducted by linear multiple regression analysis. Goal-, consequence-, and attribute-level value perceptions were found to have a positive effect on the perceived economic value of high-tech consumer products. Attribute-level value had the strongest effect on the formation of perc…
Marketing or methodology? : Exposing the fallacies of PLS with simple demonstrations
2023
Purpose Over the past 20 years, partial least squares (PLS) has become a popular method in marketing research. At the same time, several methodological studies have demonstrated problems with the technique but have had little impact on its use in marketing research practice. This study aims to present some of these criticisms in a reader-friendly way for non-methodologists. Design/methodology/approach Key critiques of PLS are summarized and demonstrated using existing data sets in easily replicated ways. Recommendations are made for assessing whether PLS is a useful method for a given research problem. Findings PLS is fundamentally just a way of constructing scale scores for regression. PL…
Advancing value-based selling research in B2B markets : A theoretical toolbox and research agenda
2023
Value-based selling (VBS) has become an increasingly important selling practice in contemporary business-to-business (B2B) markets, but currently most VBS studies are limited to exploratory and descriptive case studies. Therefore, the purpose of this paper is to develop a theoretical toolbox that provides a foundation for more theory-driven research on VBS and thereby advances both the theoretical and managerial understanding of VBS. Specifically, we consider equity theory, framing theory, mental accounting, social exchange theory, signaling theory, agency theory, game theory, and institutional theory in terms of their implications for VBS. We provide a brief overview of each theory and its…
Temporal control of xyloglucan self-assembly into layered structures by radiation-induced degradation
2016
Partially degalactosylated xyloglucan from tamarind seeds (Deg-XG) is a very appealing biopolymer for the production of in situ gelling systems at physiological temperature. In this work, we observe that the morphology of hydrogels evolves towards high degrees of structural organization with time, yielding to dense stacks of thin membranes within 24 h of incubation at 37 °C. We also explore the possibility offered by gamma irradiation of controlling the time scale of this phenomenon, the final morphology and mechanical properties of the system. Structural and molecular modifications of Deg-XG with dose are investigated by FTIR, dynamic light scattering (DLS) and rotational viscosimetry. The…
On the coupling dynamics between thermally stressed beams and granular chains
2015
The in-situ measurement of thermal stress in slender beams, or long continuous welded rails, may prevent structural anomalies. With this aim, we investigated the coupling dynamics between a beam and the highly nonlinear solitary waves propagating along a straight granular chain in contact with the beam. We hypothesized that these waves can be used to measure the stress of thermally loaded structures, or to infer the neutral temperature, i.e., the temperature at which this stress is null. We studied numerically and experimentally the mechanical interaction of one and two straight chains of spherical particles in contact with a prismatic beam that is subjected to heat. The results show that c…
Comparison of the effect of different surface treatments on the bond strength of different cements with nickel chromium metal alloy: An in vitro study
2017
Background For success of any indirect metal restoration, a strong bond between cement and the intaglio surface of metal is imperative. The aim of this study is to evaluate and compare the effect of different surface treatment on the tensile and shear bond strength of different cements with nickel–chromium alloy. Material and Methods 120 premolars were sectioned horizontally parallel to the occlusal surface to expose the dentin. Wax patterns were fabricated for individual tooth followed by casting them in nickel chromium alloy. 60 samples were tested for tensile bond strength, and the remaining 60 for shear bond strength. The samples were divided into three groups (of 20 samples each) as pe…
Ultrasonic inspection for the detection of debonding in CFRP-reinforced concrete
2017
Fibre-reinforced plastic (FRP) composites are extensively used to retrofit civil structures. However, the quality and the characteristics of the bond between the FRP and the structure are critical to ensure the efficacy of the retrofit. For this reason, effective non-destructive evaluation (NDE) methods are often necessary to assess the bonding conditions. This article presents an ultrasonic technique for detecting defects at the FRP-substrate interface. The technique uses the Akaike Information Criterion, to detect automatically the onset of the ultrasonic signals, and the novel Equivalent Time Lenght (ETL) parameter, to quantify the energy of the propagating ultrasonic signals along the i…
Influence of different parameters on drug release from hydrogel systems to a biomembrane model. Evaluation by differential scanning calorimetry techn…
2000
A comparative study on the drug release capacity of four water swellable polymeric systems was carried out by differential scanning calorimetry (DSC). The polymeric systems chosen were alpha,beta-polyaspartahydrazide (PAHy) crosslinked by glutaraldehyde (GLU) (PAHy-GLU) or by ethyleneglycoldiglycidylether (EGDGE), (PAHy-EGDGE), polyvinylalcohol (PVA) crosslinked by glutaraldehyde (PVA-GLU) and alpha,beta-poly(N-hydroxyethyl)-DL-aspartamide (PHEA) by gamma irradiation (PHEA-gamma matrices). The degree of crosslinking for PAHy-GLU, PAHy-EGDGE and PVA-GLU samples was about 0.4 and 0.8. These hydrogels were characterized as free of drugs and were loaded with diflunisal (DFN) (approximately 2.5%…