Search results for " Experiments"
showing 10 items of 315 documents
Study and evaluation of fretting critical slip conditions by applying the design of experiments method
2006
Tribological systems are complex systems that require a multi-disciplinary (mechanical, material, physico-chemical) approach where numerous influence factors can be involved. To characterize a contact couple, the intrinsic parameters of the materials as well as the parameters related to the contact loading and the surrounding environment need to be taken into account. Fretting analysis, by means of running condition-fretting maps (RCFM), allows the behavior of the contact couple to be taken into account and to predict the boundary between partial slip and gross slip conditions. This article presents the study of a steel/polycarbonate couple during fretting tests. The study was carried out b…
Get into flow: Design of experiments as a key technique in the optimization of anodic dehydrogenative C,C cross-coupling reaction of phenols in flow …
2021
Abstract The optimization of electro-organic reactions poses a challenge due to the various parameters involved. Quite often those parameters are not independent from each other, leading the experimental scientist using linear approaches into an optimization loophole. We report a strategy for the optimization of the anodic oxidative dehydrogenative C,C cross-coupling reactions for the synthesis of biphenols based on Design of Experiments (DoE), which overcomes the drawbacks of linear optimization approaches. Using a fractional design, we increased the yield of a long-time investigated example reaction from 44% up to 85% and point out different suitable reaction conditions through to linear …
Relevant factors for the eco-design of polylactide/sisal biocomposites to control biodegradation in soil in an end-of-life scenario
2017
[EN] The eco-design considers the factors to prepare biocomposites under an end-of-life scenario. PLA/sisal biocomposites were obtained from amorphous polylactide and sisal loadings of 10, 20 and 30 wt% with and without coupling agent, and subjected to biodegradation in soil according to standard IS0846. Mass loss, differential scanning calorimetry and size-exclusion chromatography were used for monitoring biodegradation. A statistical factorial analysis based on the molar mass M-n, and crystallinity degree X-c pointed out the relevance and interaction of amount of fibre and use of coupling agent with the time of burial in soil., During the preparation of biocomposites, chain scission provo…
Phonons of hexagonal BN under pressure: Effects of isotopic composition
2021
Raman scattering experiments on isotopically enriched hexagonal boron nitride have been performed under pressure up to 11 GPa at room temperature. The sublinear increase of the Raman-active E2g mode frequencies has been characterized. The pressure behavior has been analyzed by means of a bond-stiffness–bond-length scaling parameter γ which takes into consideration the vast differences in a- and c-axis compressibilities. The interlayer shear mode exhibits a γ parameter similar to that of graphite, and the mode frequency in isotopically pure samples separates faster at low pressures as a result of van der Waals interactions. Because of the extremely low a-axis compressibility, the intralayer …
Experimental Study of the Laser Cutting Process on 1C45 - 3 mm Steel
2014
The Paper Presents the Measurement Systems Analysis, System Capability and Optimization of a Laser Cutting System for 3 Mm Alloy Steel. for the Measurement System Analysis and System Capability the Data was Introduced in a Excel Sheet which was Designed According to QS9000 Standard (Measurement System Analysis) to Calculate the Measuring System Repeatability, Reproducibility and Capability. Design of Experiment (DOE) was Used for Process Optimization the Optimization was Conducted in an Operational Manufacturing Environment and was Based on the Design of a 25 Full Factorial Experiment. the Laser Parameters (input) were Feed Rate v, Gas Pressure p, Power P, Frequency F and Efficiency R while…
Situación de la enseñanza de las ciencias por indagación en los planes de estudio de Grado de Maestro de Educación Primaria en España
2020
En el presente trabajo se analizan 84 guías docentes de asignaturas de ciencias experimentales y/o su didáctica impartidas en el Grado en Maestro en Educación Primaria de universidades españolas. El análisis de la información contenida en ellas nos permite conocer la formación que proponen las guías docentes de asignaturas científicas de dicho grado y hasta qué punto la enseñanza de la ciencia por indagación está presente en su plan de formación. Los resultados indican una escasa formación científica de los futuros maestros y con poca presencia de la indagación. PALABRAS CLAVE: enseñanza de las ciencias, maestros en formación, indagación,Educación Primaria,guía docente. ABSTRACT: The presen…
Differential Gene Expression and Allele Frequency Changes Favour Adaptation of a Heterogeneous Yeast Population to Nitrogen-Limited Fermentations
2020
Alcoholic fermentation is fundamentally an adaptation process, in which the yeast Saccharomyces cerevisiae outperforms its competitors and takes over the fermentation process itself. Although wine yeast strains appear to be adapted to the stressful conditions of alcoholic fermentation, nitrogen limitations in grape must cause stuck or slow fermentations, generating significant economic losses for the wine industry. One way to discover the genetic bases that promote yeast adaptation to nitrogen-deficient environments are selection experiments, where a yeast population undergoes selection under conditions of nitrogen restriction for a number of generations, to then identify by sequencing the …
Das Blutbild und die Atmungsintensität des Misgurnus fossilis bei verschiedenen Atmungsbedingungen [Misgurnus fossilis elpošanas intensitāte un asiņu…
1935
Teksts vācu valodā, kopsavilkums latviešu valodā.
Effects of confinement and external fields on structure and transport in colloidal dispersions in reduced dimensionality
2012
In this work, we focus on low-dimensional colloidal model systems, via simulation studies and also some complementary experiments, in order to elucidate the interplay between phase behavior, geometric structures and transport properties. In particular, we try to investigate the (nonlinear!) response of these very soft colloidal systems to various perturbations: uniform and uniaxial pressure, laser fields, shear due to moving boundaries and randomly quenched disorder.We study ordering phenomena on surfaces or in monolayers by Monte Carlo computer simulations of binary hard-disk mixtures, the influence of a substrate being modeled by an external potential. Weak external fields allow a control…
Turbulence structure and implications in exchange processes in high-amplitude vegetated meanders: Experimental investigation
2018
Aquatic plants in rivers interact with flow and exert an important role in maintaining suitable habitat and ecological equilibrium. Understanding turbulence structure in the presence of vegetation is important with respect to environmental processes, such as sediment transport and mixing of transported quantities. Literature indicates that mass and momentum exchanges in the presence of vegetation are strongly influenced by the sequence of coherent structures which form between vegetated and non-vegetated zones. In the present paper we investigate turbulence structure and coherent motion in high-curvature channels with submerged vegetation. The analysis is performed with the aid of detailed …