25 research outputs found

    An experimental investigation of the fatigue damage behaviour of adhesively bonded joints under the combined effect of variable amplitude stress and temperature variation

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    Under working conditions, adhesively bonded structures are exposed to variable cyclic loading and temperature variation. However, there is still limited number of works dealing with their relationship. The present study investigates the combined effect of variable amplitude stress and variation of temperature on the fatigue damage behaviour of adhesively bonded scarf joints. Initially, experiments at constant amplitude stress, which showed reduction of fatigue strength with increasing temperature, were carried out to establish base SN curves for calculations of cumulative damage. Then, tests under variable amplitude fatigue (VAF) were performed with constant temperature and with two, four and six temperature changes. Temperatures for VAF experiments were −10, 23 and 50 °C. VAF at constant temperature demonstrated: (i) damage retardation at −10 and 23 °C and damage acceleration at 50 °C and (ii) no clear effect on the fracture mode. Conversely, VAF with temperature variation showed: (i) high damage acceleration with an increase proportional to the number of temperature changes and (ii) a trend of more adhesive failure. For lifetime predictions made with a linear damage rule, good correlation was obtained at constant temperature. However, under variable temperature conditions caution must be taken since predictions overestimated fatigue lifetime

    Returns to Education in Latvia: Evidence from EU-SILC Microdata

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    Izglītības ietekme uz algu ir plaši analizēta tēma zinātniskajā literatūrā, tomēr Latvijas gadījumā vispusīga analīze līdz šim vēl nav veikta. Šī darba mērķis ir ar ekonometriskām metodēm novērtēt izglītības ietekmi uz algu Latvijā, izmantojot EU-SILC mikrodatus (2007. – 2013. gadam). Rezultāti liecina, ka katrs izglītībā pavadītais gads palielina algu vidēji par 7.6%. Izglītības ietekme uz algu būtiski pieauga ekonomiskās krīzes periodā, kā arī tā ir augstāka sievietēm, Latvijas pilsoņiem un Pierīgā dzīvojošajiem, bet mazāka gados jauniem cilvēkiem. Latvijā raksturīga arī salīdzinoši augsta augstākās izglītības algu prēmija un salīdzinoši zema vidējās izglītības algu prēmija. Ar IM modeļiem iegūtie koeficienti ir statistiski nozīmīgi lielāki par Mincera koeficientu.Returns to education has been extensively analysed topic in literature, however empirical results for Latvia are limited. The aim of this paper is to estimate the returns to education in Latvia using EU-SILC microdata (2007. – 2013). The main findings show that additional year of schooling raises the salary by 7.6%. Returns to education were relatively high during the economic crisis. It is higher for women, citizens of Latvia, Pieriga residents, but lower for relatively young people. If compared to findings in other EU countries the returns to higher education is rather high while returns to secondary education rather low. Coefficients obtained with IM models are significantly higher than Mincer coefficient

    Generationenübergreifende Zusammenarbeit als Basis innovativen unternehmerischen Handelns

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    Die Pflegebranche sieht sich aktuell mit einer Vielzahl von Herausforderungen konfrontiert, deren Bewältigung nachhaltige Innovationen in den jeweiligen Einrichtungen erforderlich machen. Der Beitrag beleuchtet vor diesem Hintergrund den Stellenwert einer erfolgreichen innerbetrieblichen generationenübergreifenden Zusammenarbeit als Ausgangspunkt zur Aktivierung ebensolcher Potenziale. Wichtiger Eckpfeiler einer solchen Zusammenarbeit ist die Etablierung einer Organisations- und Führungskultur, die sich durch Vertrauen, Loyalität, und Generationengerechtigkeit auszeichnet. Anhand ausgewählter Ergebnisse des BMBF/ESF/EU-geförderten Verbundprojektes DOMINNO (Demografieorientierte Konzepte zur Messung und Förderung von Innovationspotenzialen) werden Ansatzpunkte zur Entwicklung und Förderung einer intergenerationalen Zusammenarbeit in Einrichtungen der Pflegebranche diskutiert und Implikationen für die Praxis aufgezeigt

    Direct measurements of particle flux along gap sides in castellated plasma facing component in COMPASS

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    In this paper, we report results of a dedicated experiment that gives the plasma penetration profiles inside a gap of a tokamak castellated plasma-facing component. A specially designed probe that recreates a gap between two tiles has been built for the purpose of this study. It allows to measure ion saturation profiles along the 2 sides and at the bottom of the gap for both poloidal and toroidal orientations. The novelty of such experiment is the real time measurement of the plasma flux inside the gap during a tokamak D-shaped discharge compared to previous experimental studies which were mainly post-mortem. This experiment was performed in the COMPASS tokamak and results are compared with particle-in-cell simulations. The plasma deposition is found to be asymmetric in both orientations with a stronger effect in poloidal gaps. The Larmor radius of the incoming ions plays a role in the plasma penetration only in poloidal gaps but seems to have little impact in toroidal gaps. Profiles are qualitatively well reproduced by simulations. Ion current is recorded at the bottom of a toroidal gap under certain conditions

    Investigation of the Impact of Transient Heat Loads Applied by Laser Irradiation on ITER-Grade Tungsten

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    Cracking thresholds and crack patterns in tungsten targets after repetitive ITER-like edge localized mode (ELM) pulses have been studied in recent simulation experiments by laser irradiation. The tungsten specimens were tested under selected conditions to quantify the thermal shock response. A Nd:YAG laser capable of delivering up to 32 J of energy per pulse with a duration of 1 ms at the fundamental wavelength λ = 1064 nm has been used to irradiate ITER-grade tungsten samples with repetitive heat loads. The laser exposures were performed for targets at room temperature (RT) as well as for targets preheated to 400 °C to measure the effects of the ELM-like loading conditions on the formation and development of cracks. The magnitude of the heat loads was 0.19, 0.38, 0.76 and 0.90 MJ m−2 (below the melting threshold) with a pulse duration of 1 ms. The tungsten surface was analysed after 100 and 1000 laser pulses to investigate the influence of material modification by plasma exposures on the cracking threshold. The observed damage threshold for ITER-grade W lies between 0.38 and 0.76 GW m−2. Continued cycling up to 1000 pulses at RT results in enhanced erosion of crack edges and crack edge melting. At the base temperature of 400 °C, the formation of cracks is suppressed

    Properties of "detached" plasmas

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    The phenomenon "detached"-plasma is described and analyzed, based on detailed experimental studies in the TEXTOR tokamak, in particular by applying comprehensive edge diagnostics. The major parameters responsible for the transition to a "detached"-plasma are identified (heating power, electron density, impurity level) and can be related to a power loss via "100% radiation cooling" from low-Z impurities at the edge. The relevance for plasma-wall interaction, as evidenced e. g. by drastic changes in heat loads to the limiter, increase of particle flux to the wall, thereby enhancing the impurity release, is discussed. The great importance of considering the "detached"-plasma properties in scaling studies and additional heating effects is demonstrated by the impact of this plasma state on particle and energy confinement times and by ICRF-heating induced transitions

    Entwicklung und Test von Prototypkomponenten für ITER

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    Das Bundesministerium für Bildung und und Forschung (BMBF) stellte in 2007/2008 Mittel imRahmen der Projektförderung zur Verfügung, mit der Zielsetzung eine stärker sichtbareBeteiligung der deutschen Fusionsinstitute am Aufbau von ITER zu erreichen, sowie dieChancen deutscher Unternehmen auf die Übernahme von Aufträgen für den Aufbau vonITER zu stärken.Eine wichtige Zielsetzung des hier beschriebenen Forschungsvorhabens (Projektnummer03FUS0007) war es demnach, kritische Prototyp-Komponenten für ITER zu entwickeln undzu testen, sowie entsprechende Mess- und Prüfeinrichtungen aufzubauen. Gleichzeitigwurde in der Projektbearbeitung sehr eng mit einer ganzen Reihe von Unternehmenzusammengearbeitet, um so einen intensiven Know-How Transfer in beiden Richtungen imHinblick auf die Entwicklung von Komponenten für Fusionsanlagen zu erreiche
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