The formation of plastic strains in non-cohesive soils due to large number of loading cycles is a phenomenon of great importance in geotechnical and civil engineering. It constitutes a considerable cause for failures and deformations in various types of engineering applications including pavements. Strain accumulation due to cyclic loading has been studied for years through different models. This thesis reviews various models and focuses on the Bochum model through which, the most contributing soil and traffic parameters on permanent strains formation in pavement subgrades can be figured out. This represents the base for studying the serviceability of increasing the gross weights of vehicles that affect the behavior and size of cyclic loading. This was discussed through investigating the efficacy of increasing the number of vehicle axles and through increasing the vehicle gross weight while keeping the number of axles to check their impacts at the levels of strain formation in soil and consequently on its deformation. The results showed a considerable difference in settlements after changing the axle configurations of vehicles through increasing its number of axles. The work is expected to open a new area of scientific research in pavement designs seeking for ideal configurations of vehicle axles and to provide an advanced approach for studying soil deformations due to higher cyclic loadings.

Ebola, a type of filovirus that causes hemorrhagic fevers, dominated global headlines in 2014 when the largest Ebola epidemic in history took place in West Africa. Healthcare practitioners were at particular risk of contracting Ebola while taking care of patients with the disease because they were easily exposed to bodily fluids such as blood, urine, saliva, and feces, quite often in the intensive care unit (ICU). While personal protective equipment (PPE) protects the healthcare practitioner by providing an effective barrier against the virus, users were also at risk for heat stress because of the type of protective clothing. In this study, coveralls made of monolithic barriers, which prevent water vapor from escaping the suit, were compared to coveralls made of micro- porous material, which allows evaporated sweat to escape the suit. The Microgard® 2000 TS Plus, made of micro-porous barrier material and the monolithic barrier Microgard® 2300 Plus were compared against a control ensemble of work clothes consisting of a long-sleeve shirt and trouser. A progressive heat stress protocol was used to determine the critical environment at the upper limit of compensable heat stress. The critical condition was the point at which the heat gain caused by wearing the protective ensemble as well as dry heat exchange was balanced by the maximum heat loss due to evaporative cooling. Wet bulb globe temperature at the critical condition (WBGTcrit ) ,total evaporative resistance (Re,T,a), and clothing adjustable factor (CAF) were calculated for each ensemble based on data at the critical point. Also at the critical condition, participant rectal temperature vi (Tre) , heart rate (HR), skin temperature (Tsk), and physiological strain index (PSI) were noted and compared for each ensemble. A two-way ANOVA (ensemble x participant) for WBGTcrit and Re,T,a as dependent variables was used to determine whether or not there were differences among ensembles. Tukey’s honest significance test was used to determine where significant differences occurred. WBGTcrit was 33.8, 26.3, and 22.9 °C-WBGT for Work Clothes, M2000, and M2300 respectively. Re,T,a was 0.012, 0.031, and 0.054 kPa m2 W-1 for WC, M2000, and M2300 respectively. The higher the WBGTcrit for an ensemble, the more it can support evaporative cooling and hence the better it is at ameliorating heat stress. Based on this trial, the micro-porous ensemble Microgard® 2000 TS Plus has better heat stress performance than vapor-barrier Microgard® 2300 Plus. As expected, there were no differences for any of the physiological metrics at the critical conditions.

L'objectif de cette thèse est d'étudier l'influence de la vitesse de déformation sur la réponse par indentation des matériaux. Les matériaux polymères thermoplastiques, notamment le Polycarbonate (PC), le Polyméthylméthacrylate (PMMA), le Polyéthylène à Haute Densité (PEHD) et le Polyamide Nylon 6.6 renforcé à 30% de fibres de verres (PA 6.6-30% GFR), ont été choisis comme matériaux d'études en raison de leur forte sensibilité à la vitesse de déformation même à température ambiante. Les deux premières parties de ce travail sont focalisées sur l'étude du comportement thermomécanique des matériaux polymères. Une étude bibliographique sur des matériaux polymères thermoplastiques, amorphes et semi-cristallins, a été effectuée afin de comprendre leur microstructure et leur mécanisme de déformation. De plus, des essais de compression simple ont été réalisés sur les matériaux d'étude à différentes vitesses de traverse constantes puis dépouillés analytiquement. Les trois derniers chapitres de cette thèse sont consacrés à la caractérisation mécanique des matériaux par indentation. En premier lieu des simulations numériques de l'essai d'indentation conique ( =70,3°) à une vitesse de pénétration constante ( = 1 µm/s) ont été effectuées à partir des paramètres de la loi de G'sell modifiée et de la loi puissance identifiés par compression. L'identification par analyse inverse des paramètres de la loi de G'sell modifiée à 7 paramètres sur des courbes pseudo-expérimentales nous a permis de confirmer la non unicité de la solution. Ainsi, nous avons effectué l'étude théorique de l'indentation sur des matériaux pseudo-expérimentaux en utilisant la loi puissance. Un nouveau concept de déformation représentative et de vitesse de déformation représentative, basé sur l'analyse du domaine de solution regroupant l'ensemble des paramètres donnant les mêmes courbes d'indentation, a été proposé. La procédure d'identification des paramètres de la loi puissance par indentation utilisant ce concept de déformation représentative et de vitesse de déformation représentative, appliquée sur un matériau pseudo-expérimental donne des résultats très satisfaisants. Sur les matériaux d'étude en revanche la méthode n'a pu révéler son potentiel puisque la loi de comportement de ces matériaux n'est pas correctement modélisée par une loi puissance sur une large plage de déformation et de vitesse de déformation. Enfin, le concept de déformation représentative et de vitesse de déformation représentative proposé dans ce travail apporte de nouveaux outils d'analyse et d'exploitation des données de l'indentation et offre des perspectives très intéressantes. / The aim of this thesis is to study the strain rate effects through materials response from indentation test. Polymeric solid material, especially Polycarbonate (PC), Polymethyl methacrylate (PMMA), High Density Polyethylene (HDPE) and Polyamide Nylon 6.6 -30% glass fiber reinforced (PA 6.6-30% GFR), were selected as study materials due to their high strain rate sensitivity even at room temperature. The first two parts of this work were focused on the study of the thermomechanical behavior of polymer materials. Bibliographical studies of thermoplastic polymer materials, amorphous and semi-crystalline, was established in order to understand their microstructure and deformation mechanism. Moreover, compression tests were performed on study materials with several crosshead speeds values then the results was exploited analytically. The last three parts were focused on mechanical characterization using Instrumented Indentation Test (IIT). Firstly, numerical simulation of a conical indentation test ( =70.3°) with a constant rate displacement ( = 1 µm/s) was established using the identified G’sell behavior parameters and the power-law parameters from compression test. Parameter identification using Inverse Analysis from numerical material shows the non-uniqueness of G’sell parameters which gives the same indentation curve. Thus, theoretical study of conical indentation test was established considering power-law model. A new concept of the representative strain and the representative strain rate, based on solution domain which associate the set of parameters leading to the same indentation curves, was proposed. Very satisfactory results was obtained when identification process using this average representative strain rate is applied to a numerical material define by a power-law model. However, this method could not show its efficiency because the mechanical behavior of the real material is not correctly modeling with a power-law at a wide range of strain and strain rate. Finally, the new concept of the representative strain and the representative strain rate proposed on this work contributes to a new investigation tools to exploit the results form IIT and provide a very interesting perspectives.

Le remodelage myocardique est une réponse du myocarde à une altération des contraintes pariétales générée par une agression aiguë (ischémie myocardique) ou chronique (surcharge en pression, surcharge en volume, anomalie métabolique). En effet, le cœur est un organe capable de modifier en fonction de ses conditions de travail l’expression de ses fonctions moléculaires et cellulaires pour aboutir à des changements de taille,de morphologie et de fonction. Le remodelage myocardique est un mécanisme adaptatif initialement bénéfique, car en modifiant sa géométrie, le ventricule gauche s’adapte aux modifications de stress pariétal et préserve le volume d’éjection systolique. / Not transmitted

No presente trabalho foram estudados os fenômenos de encruamento e, principalmente, a formação e reversão da martensita alfa-linha (a\', cúbica de corpo centrado, CCC, ferromagnética) induzida por deformação em um aço inoxidável dúplex UNS S31803 e um super dúplex UNS S32520. Inicialmente, as microestruturas dos dois materiais na condição solubilizada foram caracterizadas com auxílio de várias técnicas complementares de análise microestrutural. Foram determinadas fração volumétrica, estrutura cristalina, composição química, tamanho e morfologia das duas fases (ferrita e austenita). Posteriormente, os dois aços foram deformados por dois métodos: a laminação a frio, dividida em vários estágios, com menores graus de deformação e a limagem, sendo que o cavaco limado resultante apresenta altos graus de deformação. Algumas amostras deformadas foram recozidas. Os fenômenos de encruamento, formação e reversão de martensita induzida por deformação na austenita, recuperação, recristalização da austenita e da ferrita no cavaco limado foram estudados predominantemente por difratometria de raios X e usando o método de Rietveld. A difratometria de raios X também foi utilizada para determinação das microdeformações residuais e tamanhos de cristalito (subgrão), calculadas a partir do alargamento dos picos de difração causado pelas deformações. Desta forma, puderam-se comparar os níveis de deformação da laminação e limagem. Qualitativamente, a formação e reversão da martensita induzida por deformação também foi estudada por meio de medidas magnéticas utilizando-se dados de saturação magnética das curvas de histerese obtidas com o auxílio de um magnetômetro de amostra vibrante. Observou-se que para o aço inoxidável dúplex, tanto a laminação quanto a limagem causaram a formação de martensita induzida por deformação e para o aço inoxidável super dúplex, apenas a limagem promoveu essa transformação. Em comparação com o aço dúplex, o aço super dúplex apresentou maior resistência à formação de martensita induzida por deformação, pois apresenta uma austenita mais rica em nitrogênio e uma maior propensão à formação de fase sigma durante o recozimento, pois apresenta uma ferrita mais rica em cromo e nitrogênio. / In the present work the phenomena of strain hardening, formation and reversion of the strain induced alpha-prime martensite (a\', body centered cubic, BCC, Ferromagnetic) in an UNS S31803 duplex and UNS S32520 super duplex stainless steels have been studied. Firstly, the microstructures of both materials in the solution annealed condition were characterized with the aid of several microstructural analysis complementary techniques. The volume fraction, crystalline structure, chemical composition, size and morphology of the two phases (ferrite and austenite) have been determined. Further, both steels were deformed by two methods: cold rolling, divided into several stages, with lower strain levels than filing, which the chips resulting had higher strain levels. The phenomena of strain hardening, formation and reversion of strain induced martensite in the austenite phase, recovery and recrystallization of austenite and ferrite phases have been studied, mainly using X-ray diffraction and the Rietveld method. X-ray diffraction was also used to determine the residual microstrain and crystallite size (sub grain), calculated from the diffraction peak broadening caused by straining. Thus, the levels of cold rolling and filing strains could be compared. Qualitatively, the formation and reversion of strain induced martensite was also studied by magnetic measurements using data from magnetic saturation of hysteresis curves obtained with the aid of a vibrating sample magnetometer. It has been observed that for the duplex stainless steel, both filing as well as cold rolling promoted strain induced martensite. On the other hand, for the super duplex stainless steel, just filing promoted this transformation. In the comparing with duplex, the super duplex stainless steel austenite is more stable that is why is richer in nitrogen, so, the strain induced martensite formation is more difficult. The easier sigma phase precipitation during annealing as well in the super duplex stainless steel is due higher levels of chrome and molybdenum than the duplex stainless steel.

This master´s thesis deals with determination of pressure in the pipe using foil strain gauge. It is calculation of the pressure from the measured strain. The main purpose of this work is devise mathematical-technological models to determinate internal pipe pressure from longitudinal deformation. Devised models were used on data from realized experiment and results were compared with real value of pressures in pipes. This thesis contains three models which were mutually compared. Sensitivity analysis were done on two of these models. Thesis also contains opening research of strain gauge problematics. Description of basic knowledge of physical objects mechanic with focusing on shells also belongs to this theoretical part.

<p>Stress relaxation in tin films can result in microstructural changes visible on the surface, referred to as “surface defects,” and can include whisker and hillock formation, cracking, nucleation of new grains, and grain growth. Sn whiskers are of particular concern for microelectronics reliability in which Sn whiskers growing from component surface and cause catastrophic short-circuiting. While prior research has identified the conditions and mechanisms for surface defect evolution during aging and thermal cycling, the response of tin films due to mechanical stress, especially high frequency vibration, is not fully understood. In practical terms, high frequency vibration is an important source of mechanical stress generation in microelectronics for automotive and aerospace applications. This research, based on high frequency vibration of cantilevers, adds to the existing mechanisms for stress relaxation process in metal thin films, not just for tin films, as well as proposed new mechanisms for such processes.</p> <p>In the first study, the piezoelectric drive of small atomic force microscopy (AFM) cantilevers vibrated at resonance are used for high frequency cyclic bending experiments. Intermetallic (IMC) formation as well as initial film morphology and thickness (corresponding to surface grain size) all influence the response of tin films for cyclic bending. A laser doppler vibrometer (LDV) system was used to identify the real-time strain along the cantilever during cycling, suggesting that the small strains are responsible for the limited nucleation and growth for defects though the defect density increases with the number of cycles and strain distribution along the cantilever.</p> <p>In the second study, the effect of larger strains on defect evolution was determined using vibration of larger cantilevers at resonance as a function of number of cycles, frequency, temperature, and whether the vibration was continuous or interrupted for SEM characterization of defect type and density. In addition to typical micro-sized whiskers and hillocks, intragranular breakup (IGB) with intrusions and extrusions and nanowhiskers (NWs) with diameters < 1 𝜇m were observed. Both increasing number of cycles and strain amplitude/rate promote defect formation for a fixed frequency, with the defect density being strongly frequency dependent.Vibration at low temperature and interrupting measurements for SEM characterization affected the relative densities. The density of larger surface defects is strongly influenced by interruptions while NW density is almost unaffected. </p><p>Both low resonant frequency and low T (223 K) promote IGB formation during cyclic bending due to large maximum strain amplitude and slower diffusion/creep at low T, respectively. Though the overall defect density for low T is smaller than that at room temperature (RT), the response of films is similar to that at RT, indicating the same mechanisms. The defect density decrease at low T is mainly determined by NW formation, and there is a transition from micro-sized surface defects to IGBs for cyclic bending at low T.</p><p>This research demonstrated that cyclic bending of cantilevers can be used to quantify the stress relaxation of tin films in an important stress regime for microelectronics and to develop defect mitigation strategies to improve the reliability of interconnects in electronic applications.</p>

Syfte: Syftet med denna studie var att undersöka om ett kortare synavstånd till smartphone resulterar i mer ögonrelaterade symtom. Metod: Deltagarna var slumpmässigt tillfrågade mellan åldrarna 19 och 37 år. Deltagarna (n=63) fick svara på symtomenkäten Convergence insufficience symptom survey (CISS) gällande närseende och läsning. Under tiden mättes synavståndet mellan deltagarnas ögon och smartphone. Symtomenkäten var webbaserad och deltagarna svarade med sin smartphone. Höjden på versalen [H] mättes och tillsammans med synavståndet räknades synvinkeln ut. Resultat: 76% av deltagarna var kvinnor, 22% var män och 2% saknade könstillhörighet. Deltagarnas medelålder var 24 år. Studien indikerade inte på ett statistiskt signifikant samband (r=0,219, p=0,102) mellan CISS-poäng och synavstånd till smartphone. Däremot indikerades en svag korrelation mellan de två variablerna. Resultatet visade även att endast 2 deltagare i studien hade en mindre synvinkel än 16 bågminuter. Slutsats: Denna studie fann inget statistiskt signifikant samband mellan synavstånd till smartphone och astenopiska besvär. Däremot påvisar studien en svag korrelation mellan synavstånd till smartphone och astenopiska besvär.

Syftet med denna uppsats är att undersöka hur incels talar om våld, vilken betydelse våld har för incel-kulturen och incels identitetsskapande. Incels är ett relativt nytt fenomen, som ägnats mer uppmärksamhet i samband med ett antal våldsamma incel-attacker under 2010-talet. Attackerna har riktat sig mot civilsamhället, och har enligt Totalförsvarets forskningsinstitut (FOI) ofta föregåtts av att gärningsmannen spenderat tid på incel-forum (2020, s. 1). Denna iakttagelse om korrelationen mellan incelforum och incel-attacker föranledde utförandet av den här studien. Studiens material utgörs av 511 inlägg från våldsrelaterade diskussionstrådar på hemsidorna incels.net och incels.is, vilka undersöktes med en kvalitativ analys av meningsinnehåll. Resultatet visade att inlägg av våldsbejakande karaktär var mycket vanligt förekommande. Resultatet visade även att teman som kvinnohat, offerskap och icke-våldsbejakande ofta återkom. Det teoretiska ramverket för studien har varit en triangulering av Agnews teori om General strain, Connells maskulinitetsteori och Goffmans teori om stigma. Utifrån dessa teorier kan våldsbejakande diskurs förstås som en hantering av strain, ett iscensättande av maskulinitet och en reaktion på stigma. Resultatet i den här studien bekräftar till stor del tidigare forskning på incels, men det går att konstatera att ytterligare forskning krävs för att förstå varför incels är våldsbejakande, och vilken betydelse internetforum har för incel-kulturen och incel-attacker. / The aim of this study was to examine in what way incels discuss violence, as well as how significant violence is for the incel-culture and their identity. Incels are a relatively new phenomenon, which has been more closely examined following recent attacks perpetrated by incels. The attacks have been aimed at civilians, and according to the Swedish Defence Research Agency (FOI), these attacks have often been preceded by the perpetrator spending time on incel forums (2020). This observation regarding the correlation between incel forums and incel attacks inspired the approach of this study, which aims to shed light on how incels talk about violence, and what role violence plays within the online incel community. The empirical material for this study consisted of 511 posts made on violence related threads from the websites incels.net and incels.is. The study applied qualitative analysis of data to examine the research questions, and the result showed that pro-violence was a common theme within the material. The result also showed that misogyny, feelings of injustice and anti-violence were recurring themes. Agnew’s General strain theory, Connell’s theory of masculinity and Goffman’s theory of stigma was used as a theoretical framework to analyse the material. Using these theories, the study explains the identified themes as coping strategies for strain, attempted staging of masculinity and a reaction to stigma. The results in this study confirm previous research made on the subject, but more research is needed to fully understand the ways incels talk about violence and the significance of violence within the incel community.

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