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Abstract The primary objective of this work is to study and model the fracture process and durability of paperboard cores in cyclic loading. The results are utilized in creating analytic model to estimate the life time of cores in printing industry. The life time means here the maximum number of winding-unwinding cycles before the core delaminates. This study serves also as an example of use of board as a constructional engineering material. Board is an example of complicated, fibrous, porous, hydroscopic, time dependent and statistic material. Different core board grades are typically made of recycled fibers. The material model in this work is linear-elastic, homogeneous and orthotropic. The material characteristics, elastic and strength properties are studied first. Then the material is studied from the points of view of fracture and fatigue mechanics. Some of the analysis and test methods are originally developed for fiber composites but have been applied successfully here also for laminated board specimen. An interesting finding is that Scott Bond correlates well with the sum of mode I and mode II critical strain energy release rates. It was also possible to apply Paris' law and Miner's cumulative damage theory in the studied example situations. The creation of the life time model starts by FEM-analysis of cracked and non cracked cores in a typical loading situation. The elastic-linear material model is used here. The calculated stresses are utilized in analytic J-integral model. The agreement between analytic and numerical J-integral estimations is good. The analytic life time model utilizes the analytic J-integral model, Miner's cumulative damage theory and analytically formulated Wöhler-curves which were constructed by applying the Paris' law. The Wöhler-curves were constructed also by testing cores to validate the theoretical results. The testing conditions are validated by FEM-analysis. The cores heat up when tested or used with non expanding chucks and a temperature correction was needed in the life time model to consider this. Also, single or multi crack model was used depending on the studied case. The calculated and tested durability prediction curves show good correspondence. The results are finally reduced to correspond to certain confidence level.

Thesis (D. Min.)--Western Seminary, Portland, OR, 2004. / Abstract. Includes bibliographical references (leaves 160-164).

Thesis (D. Min.)--Western Seminary, Portland, OR, 2004. / Abstract. Includes bibliographical references (leaves 160-164).

Thesis (D. Min.)--Western Seminary, Portland, OR, 2004. / Abstract. Includes bibliographical references (leaves 160-164).

Popular messages not only illuminate many of the struggles people experience wrestling with the tensions between work and home life, but these popular texts also influence the behaviors of those who consume them. They not only reflect organizational members' experiences, but they also shape what they do. The following dissertation provides a theoretical discussion that conceptualizes and locates popular messages within dominant cultural patterns and explores the role of popular discourse in socializing organizational members. Next, "work-life" research is understood in terms of enactments and construals of time. This discussion not only develops a temporal perspective for "work-life" research, but also highlights inequalities embedded in the current "work-life" research. A narrative approach is offered as a theoretical perspective and methodological tool for uncovering perspectives. Sixty-seven participants are interviewed, and findings suggest differing perspectives on work-life balance, work-life expectations, and the role popular messages play in shaping work-life expectations vary along gender, socioeconomic, and generational lines. Further, analyses of interview data reveal gender and socioeconomic inequalities exist within the "work-life" construct and differing construals of time. / text

La production d’hydrogène et de dioxygène par électrolyse PEM (PEM « Proton Exchange Membrane ») de l’eau s’effectue grâce à la présence de métaux nobles dans les couches catalytiques: à la cathode, le platine supporté sur du carbone est généralement utilisé (les chargements en métaux nobles sont faibles de l’ordre de 0,5 mg/cm²) ; à l’anode, la production d’oxygène s’effectue à des potentiels élevés (> 1,6 V vs. ESH). Les oxydes de métaux nobles sont utilisés seuls dans la couche active anodique et servent à la fois de catalyseurs et de conducteurs électroniques. Comme ils sont parmi les métaux les plus denses, pour obtenir une continuité électrique de la couche anodique, les chargements doivent être très élevés, de l’ordre de 2-3 mg/cm².Cette thèse propose ainsi de développer de nouveaux matériaux supports stables électrochimiquement et bons conducteurs électroniques pour séparer les fonctions de catalyse et de conduction électronique. Pour cela, des assemblages membrane électrodes intégrant des particules de titane comme support de catalyseur anodique ont été préparés dans notre laboratoire. Testés en mono-cellule de 25 cm², leurs principales caractéristiques ont été déterminées par voltampérométrie cyclique, spectroscopie d’impédance et grâce à des courbes de polarisations à différentes températures. La comparaison des résultats obtenus entre ces anodes « innovantes » et celles à base de catalyseur seul a permis de mettre en évidence la présence d’un chargement anodique seuil de 0,5 mg/cm² en dessous duquel la présence d’un support de catalyseur est nécessaire pour assurer la percolation électrique. Grâce à l’utilisation de ce support de catalyseur bon marché, les chargements anodiques ont pu être réduits jusqu’à des valeurs aussi faibles que 0,1 mg/cm² IrO2, soit une réduction de dix fois au minimum par rapport aux taux généralement employés dans la littérature, tout en maintenant des performances identiques. / It is expected that PEM water electrolysis will play a significant role in the hydrogen society as a key process for producing hydrogen from renewable energy sources but before this, substantial cost reductions are still required. Because of the high acidity of membrane materials used in PEM water electrolysers, expensive noble-metals or their oxides are required as electrocatalysts (platinum for hydrogen evolution and iridium for oxygen evolution). As the oxygen evolution reaction takes place with a large overpotential (anodic potential > 1.6 V) only few materials can be used to avoid corrosion. In state-of-the-art, noble metal oxides are generally used alone in the active layer with typical loadings of 2-3 mg/cm² and act as both catalyst and electronic conductor.In order to reduce the noble metal loadings and keep a good electronic conductivity of the catalytic layer, iridium can be supported onto a conductive and electrochemical stable material support. To gain more insights, several MEAs with anodes made of pure iridium oxide or 50 wt % IrO2/Ti anodes have been prepared and characterized using cyclic voltammetry and impedance spectroscopy, and by measuring polarization curves at different operating temperatures. Without the catalyst support, anodic loadings can be reduced down to 0,5 mg/cm² without any degradation in the electrochemical performances. By using anodes made of iridium oxide and titanium particles, further reductions of anodic loading can be made down to 0.1 mg/cm² with performances similar to those obtained with conventional loadings of several mg cm-2.

The accelerated lifetime model is considered. To test the influence of the covariate we transform the model in a regression model. Since censoring is allowed this approach leads to a goodness-of-fit problem for regression functions under censoring. So nonparametric estimation of regression functions under censoring is investigated, a limit theorem for a L2-distance is stated and a test procedure is formulated. Finally a Monte Carlo procedure is proposed.

Didelis energijos suvartojimas yra labai svarbi detalė sistemoms, naudojančioms baterijas: nešiojami kompiuteriai, delninukai, mobilieji telefonai ir t.t. Pradėjus naudoti objektiškai orientuotas sistemas, buvo susirūpinta energijos taupymu. Todėl išsiaiškinus, kokią įtaką daro objektiškai orientuotos sistemos baterijos gyvavimo ciklui, galima būtų padėti programuotojams kurti tokias programas, kurios vartoja mažiau energijos. Darbe sukuriau programą, kuri sodina bateriją. Programoje naudojamos išretintos matricos. Pasinaudojus išretintų matricų saugojimo pagal eilutes metodu, kuris leidžia sumažinti matricos formatą, išmetant nulinius elementus, galime stebėti, kaip keičiasi sistemos resursų sunaudojimas, keičiant pradinėje matricoje nulinių elementų skaičių. Atlikę daugybą, galime įvertitni, kiek energijos suvartojo optimizuotas programos kodas ir neoptimizuotas. Atlikus eksperimentą, rezultatai parodė, jog optimizuotas kodas žymiai mažiau nusodina bateriją nei neoptimizuotas. To pasekoje galime daryti išvada, kad sistemos, kuriose yra optimizuotos programos, veiks ilgiau nei sistemos su neoptimizuotu kodu. / Low power consumption is a major constraint for battery-powered system like computer notebook or pocket PC, mobile phone. In the past, specialists usually designed both specific optimized equipments and codes to relief this concern. Doing like this could work for quite a long time, however, in this era, there is another significant restraint, the time to market. To be able to serve along the power constraint while can launch products in shorter production period, objectoriented programming (OOP) has stepped in to this field. In work we create program, whose multiply sparse matrix. Multiplication are two types: one we use standart matrix multiplication, other use compresed matrix storage by rows multiplication. When execute program, we can track, how battery power are consumpt. When we use compresed matrix storage by rows multiplication, we eliminate zero elements and multiplication execute faster, then standart matrix multiplication. So baterry power comsumption are lower. If your system are very important battery life time, then you must use optimized programm code. Optimized programm code use less battery power, then not optimized. Then your system can work much longer.

The thesis deals with problems concerning lead free soldering especially the study of the structure of solder joints and their reliability. The thesis evaluates lead free solder alloys. The theoretical part includes basic principles of soldering and methods of investigating solder joints reliability. The experimental part deals with the impact of water cooling and vibration on solder joint structure. Both methods are tested and are evaluated with regard to their reliability. The used tests include X-ray inspection, optical inspection, mechanical tests, investigating joint structure with electrone microscope.