El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / At present, the construction of highways in Andean areas the connect the various most important towns and cities in South America has become has become a key element for its development, since these routes and viaducts allow free access to cover basic needs of education, work, food and health of the population. Much of the land in these areas is clay soils whose behavior is quite unpredictable because they present abrupt volume changes according to the variation of saturation in the soil. People who travel on roads on slopes of this type of soil are at high risk due to the slippage that the slopes suffer each year. The most recent was on April 3, 2020 because of the heavy rainfall that was registered in the area; there was a landslide that affected communication channels in the department of Cajamarca in Peru [1]. In this type of slopes landslides occur when the clayey soil is specifically saturated, because under these conditions the soil is not stable and loses cohesion between its particles, therefore it is important to make slope stability studies taking into account the partially saturated soil. This article presents results of tests allow to recognize the physical characteristics of the clay soil in the province of Chepén in Cajamarca. In addition, the filter paper method is used to elaborate the soil-water characteristic curve and a series of direct shear tests are carried cut at different degrees of saturation. With these results, the partially saturate soil fault surface is constructed that allows visualizing the value of the shear stress of the soil according to the saturation to which it is subjected. This value will be important for calculating the safety factor that the slope floor must have of the resistance shear of the soil according to the saturation, this value will be important for the calculation of the safety factor that the floor of the slope must have so that it does not fall. Therefore, considering this condition of the partially saturated soil in the slope stability analysis provides values of the safety factor that are closer to reality, without the need to carry out the analysis in the most critical condition, such as what it done in classical soil mechanics.

The purpose of this paper is to derive minimal sufficient statistics for the balanced incomplete block design and the group divisible partially balanced incomplete block design when the Eisenhart Model III (mixed model) is assumed. The results are identical to Hultquist and Graybill's (1965) and Hirotsu's (1965) for the same model without interaction, except for the addition of a statistic, ∑ijY2ij•.

Research on biosynthesis of tobacco mosaic virus (TMV) ribonucleic acid (RNA) in vitro has been reported by Cochran, et al; Karasek and Schramm; Kim and Wildman; Cornuet and Astier; and Tongur and Baland in. It has been postulated that the replication of a number of viruses containing single-stranded RNA is accompanied by the formation of a virus-specific double-stranded helical RNA, the replicative form. This has been demonstrated both for animal and bacterial viruses including MS2. The double helical structure of purified replicative form of MS2 was established by X-ray diffraction studies. One of the strands was shown to be a viral RNA strand of the parental type ("plus" strand), the other being complementary to it ("minus" strand). Studies on Escherichia coli infected with RNA phages suggest that a structure containing both a "plus 11 and a "minus " strand is an obligatory intermediate in viral reproduction.

Dans le cadre de calcul des assemblages de structures, les bureaux d'études sont à l'heure actuelle encore limités dans la possibilité de mener des travaux d'optimisation. En effet, la résolution numérique des assemblages nécessite la mise en œuvre de méthodes capables de prendre en compte différents types de non-linéarités (frottement, contact et jeux entre pièces). Le coût de calcul associé à ces méthodes est généralement trop important pour mener une optimisation globale nécessitant un trop grand nombre d'évaluations. Afin de pallier à ce problème, ce travail s'appuie sur une démarche d'optimisation à deux niveaux de modèles. Le premier niveau d'optimisation consiste à la création d'un métamodèle sur lequel est effectué une optimisation globale. Le second niveau d'optimisation consiste à mener à bien une optimisation locale sur le modèle mécanique réel. Cette optimisation locale s'appuie sur les résultats trouvés au premier niveau. Deux outils sont principalement utilisés au cours de cette thèse. Tout d'abord les simulations numériques sont réalisées à l'aide de la méthode LaTIn multiparamétrique qui assure la réduction des temps de calcul associés aux multiples résolutions du problème mécanique. L'autre outil plus largement développé au cours de ce travail s'appuie sur la construction de métamodèles multi-fidélité. En effet, la méthode LaTIn est une méthode de calcul itérative, il est alors possible d'avoir accès à un indicateur d'erreur servant de niveau de convergence pour les différents calculs numériques effectués. La construction de métamodèles multi-fidélité a pour particularité de pouvoir incorporé différentes sources d'informations qui sont dans ce travail dites "totalement convergé" lorsqu'un calcul est effectué à convergence et "partiellement convergé" lorsqu'un calcul est stoppé avant convergence. Différentes méthodes multi-fidélité sont testées dans ce travail sur plusieurs exemples mécaniques afin de déterminer les plus performantes. Deux cas industriels sont également traités. / Optimisation strategies on assembly design are often time expensive on industrial case. The main difficulties are due to the non-linearties of the calculation (contact, friction and gap between pieces). The computation cost can be too expensive to lead a global optimization with a large number of evaluation of the mechanical problem.In order to achieve this kind of optimization problems, this work purposes to use a two-levels models optimization strategy. THe first level is defined thanks to the construction of a metamodel which is used to lead a global optimization. On the second level, a local optimization is used on the real mechanical model thanks to the results got from the first level.Two main tools are used in this work. The first one is the multiparametric LaTIn method which enables to reduce drastically the computational time for solving several similar mechanical assembly design problems. The other tool is the one which is the most developped in this work is the constrcution of multi-fidelty surrogate models. Indeed, the LaTIn method in an iterative method, so it is possible to define an error indicator which can be used as a level of convergence of the calculation. The construction of multi-fidelity metamodels has for particularity to incorpore several kind of information which are named as "totally converged" if the calculation has been converged and "partially converged" if the calculation has been stopped premarturly.Different multi-fidélity methods have been investigated in this work on several mechnaical examples in the aim to define the most performant. Industrial case test are trated in this thesis.In order to achieve this kind of optimization problems with an acceptable computational time, this work propose to use a two-levels model optimization strategy based on two main tools: (1) the multiparametric strategy based on the LaTIn method that enables to reduce significantly the computational time for solving many similar mechanical assembly problems and (2) a cokriging metamodel built using responses and gradients computed by the mechanical solver on few sets of design parameters. The metamodel provides very inexpensive approximate responses of the objective function and it enables to achieve a global optimisation and to obtain the global optimum. The cokriging metamodel was reviewed in detail using analytical test functions and some mechanical benchmarks. The quality of the approximation and the building cost were compared with classical kriging approach. Moreover, a complete study of the multiparametric strategy was proposed using many mechanical benchmarks included many kinds and numbers of design parameters. The performance in term of computational time of the whole optimisation process was illustrated.

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Delvis distribuerade team (partially distributed teams, PDT:s) kan beskrivas som en hybridav traditionella samlokaliserade och fullt distribuerade virtuella team. PDT:s är team som har minst en samlokaliserad subgrupp och minst två subgrupper som är geografiskt distribuerade och kommunicerar med varandra framförallt via digitala media. PDT:s har mycket gemensamt med både traditionella samlokaliserade och fullt distribuerade virtuella team, men har också specifika egenskaper och utmaningar som ledare för PDT:s behöver hantera. För den här kvalitativa studien har vi genomfört intervjuer med nio formella ledare (chefer) för PDT:s. Vårt syfte har varit att bidra med kunskap om och ökad förståelse för formella ledares erfarenheter av att leda PDT:s, med fokus på de utmaningar som ledarskap inom PDT:s innebär och ledarnas strategier att hantera dessa utmaningar. Vi har valt att intervjua formella ledare eftersom det är de som har ansvaret för att verksamheten bedrivs i enlighet med de mål som satts upp av organisationen. Vi har använt oss av en egenutvecklad analysmodell baserad på en metafor om ledarskap i PDT:s som ett hav som ledare behöver navigera i. Vårt metaforiska hav består av tre skikt. Det djupaste skiktet föreställer ledarskapets substans. Det mellersta skiktet utgörs av teorier om virtuellt ledarskap, där teorin om paradoxalt virtuellt ledarskap är en central del. Det översta skiktet i havet utgörs av teorierna om PDT:s särdrag och ledarskap i PDT:s, såsom strukturella aspekter, uppkommande ledare, virtuellt avstånd, ingruppsdynamik och olika normer för elektronisk kommunikation. Vi har läst vårt empiriska material utifrån modellen och genomfört en tematisk analys. Slutsatsen är att  arbete i PDT:s ställer nya krav på ledare. Utöver att bekräfta delar av den tidigare forskningen rörande PDT:s bidrar vi till forskningen och ledarskapspraktiken genom att ha identifierat fler paradoxer och avstånd som ledare för PDT:s måste förhålla sig till: placeringsbehovsparadoxen,gruppidentitetsparadoxen, den självgående subgruppens paradox, utanförskapets paradoxoch emotionellt avstånd. Vi bidrar också genom att tematiskt identifiera fyra nya övergripande utmaningar som ledare i PDT:s möter: strukturella utmaningar, relationella utmaningar, utmaningar som rör brist på jämlikhet och utmaningar som rör de ovan nämnda paradoxerna. Vi beskriver även strategier som ledare för PDT:s som vi intervjuat använder för att hantera dessa utmaningar. / Partially distributed teams (PDTs) can be described as a hybrid of traditionally collocated and fully distributed virtual teams. PDTs are teams that have at least one collocated subgroup and at least two subgroups that are geographically distributed and communicate with each other primarily through electronic media. While sharing many characteristics with both traditionally collocated and fully distributed virtual teams, PDTs also have their unique characteristics and challenges that PDT-leaders have to handle. For this qualitative study, we interviewed nine formal leaders (managers) for PDTs. Our aim has been to contribute with knowledge about and provide a deeper understanding of formal leaders’ experiences of leading PDTs, with the focus on challenges that PDT-leadership entails and leaders’ strategies to deal with these challenges. We have chosen to interview formal leaders because they are the ones who are responsible for the organisational activities to be conducted in accordance with the goals set up by the organisation. The leadership-in-PDTs-model we have developed is based on a metaphor representingl eadership in PDTs as a sea which leaders need to navigate. This metaphoric sea consists of three layers. The deepest layer represents the substance of leadership. The middle layer consists of virtual leadership theories, among which the theory of paradoxical virtual leadership is central. The upper sea layer consists of theories about PDTs’ unique characteristics and leadership in PDTs. These theories concern structural aspects of PDTs,emergent leaders, virtual distance, ingroup dynamics and different electronic communication norms. We have studied our empirical material based on thel eadership-in-PDTs sea model and conducted thematic analysis. The conclusion is that work in PDTs places new demands on leaders. In addition to confirming parts of the previous research on PDTs, we contribute to the research and to leadership practice by identifying other paradoxes and one more aspect of virtual distance in PDTs: location needs-paradox, the group identity paradox, the self-governing group paradox, the exclusion paradox and emotional distance. We also contribute by thematically identifying four new overall challenges met by leaders in PDTs: structural challenges, relational challenges, challenges related to lack of equality and challenges related to the above mentioned paradoxes. We also describe strategies the leaders we interviewed use to meet these challenges.

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<p> The stress relieving mechanisms in two different batches of thermal-shock resistant calcia-PSZ have been investigated. The nature of the stress relief in the two materials appears to result from the transformation of the pure ZrO₂ component of the microstructure at temperatures below, within, and above the normal transformation temperature range. In the batch #1 material, which contains a larger volume fraction of monoclinic phase, the cubic matrix material behaves in a "brittle" fashion resulting in the production of a high density of microcracks in the body. The density of these cracks is such that the level of energy that can be stored in the body is limited and thermal shock resistance results. The batch #2 material contains considerably less monoclinic material and the evidence suggests that the cubic matrix within it can act in a ductile fashion. This ductility together with the twinning of the monoclinic component of the microstructure possibly relieves the stresses developed in the material on thermal shock. </p> <p> In the batch #2 material, large platelets were observed to develop following thermal cycling from temperatures above those of the normal transformation. It has been demonstrated that stress plays a major role in the development of these features. In view of the possible ductility of the cubic matrix in this material it is suggested that the thermal cycling "works" the material, texturing the pure zirconia component in it, so leading to the development of the observed platelets. </p> / Thesis / Master of Engineering (ME)

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