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Environmental stress cracking (ESC) is a significant problem that has plagued the plastics industry since its discovery nearly 70 years ago. The accelerated brittle failure brought about when a stressed polymer comes in contact with an aggressive environment can happen suddenly with destructive results. Many classes of polymers are susceptible to this type of slow crack growth; however special emphasis has typically been placed on polyolefins due to their wide range of working environments, market dominance and their seemingly chemical resistance. Much research has been focused on formulating environmentally resistant materials, while the evaluation techniques for gauging environmental stress cracking resistance (ESCR) seem to have been left behind. This research focuses on developing a reliable testing technique for evaluating the ESCR of polyethylene resins. Passive acoustic monitoring was adapted to an industrially accepted ESCR test in an attempt to hear polymer damage before it was visually apparent. It was discovered that the low energy released during the early stages of damage and excessive background noise masked passive signals, making this method of evaluation impractical. Alternatively, active ultrasonic monitoring through velocity and attenuation measurements was investigated to see if probing techniques could be used to detect structural damage. Active ultrasonic monitoring of static and tensile stressed samples were able to differentiate plasticization after ageing, however no indication of ESCR properties could be inferred. A novel forced based monitoring system was developed in response to the acoustic testing techniques. Force monitoring was able to provide useful information regarding the failure cycle of ESC and the acquired profiles could describe a failure onset time. Several ageing environments were also tested with force monitoring and a traditional ESCR test to reveal the stress cracking ability of biodiesel, an important finding. / Thesis / Master of Applied Science (MASc) / Accelerated failure of stressed plastics can occur upon exposure to fluids through a phenomenon known as environmental stress cracking (ESC). The following research outlines the development of a novel testing technique to gauge a material’s environmental stress cracking resistance (ESCR). Adaption of passive acoustics to an existing stress cracking test was unable to provide any indication of ESCR, however the use of active ultrasonics was able to show sample plasticization. A novel forced based measuring technique was found to uniquely map the failure progression of a sample undergoing ESC, providing valuable information for understanding the phenomenon. Additional testing was also completed on various environmental fluids to reveal biodiesel’s ability to provoke ESC, an important observation.

Les évolutions des processus de conception tendent à l'intégration grandissante des outils numériques, notamment les simulateurs de conduite, dans les boucles de validation. Il est donc nécessaire de construire des méthodologies d'usages adaptées pour répondre à ces nouvelles contraintes et d'explorer les nouvelles possibilités que ces outils peuvent offrir. L'évaluation des prestations dynamiques de conduite est abordée ici dans le cas du contrôle de la trajectoire en virage soumis à des perturbations. L'objectif de ces travaux est de proposer une méthodologie d'évaluation subjective, sur simulateur, des prestations liées à la dynamique du véhicule et de l'appliquer pour la caractérisation d'un système de correction de trajectoire. Des études expérimentales sur simulateur, en présence et en l'absence de restitution inertielle du mouvement, ont été conduites pour valider une méthodologie d'évaluation et identifier les indices sensoriels mis en jeu. Une modélisation basée sur les relations psychophysiques classiques a été proposée pour relier les jugements subjectifs aux données objectives du comportement dynamique du véhicule. Enfin, l'utilisation de cette modélisation a été utilisée pour caractériser le déclenchement d'un système d'aide au contrôle de la trajectoire (ESC). Ces travaux ont été réalisés dans le cadre d'une thèse CIFRE (contrat ANRT n° 1181/2008) à RENAULT, Centre Technique de Simulation et à l'Institut de Recherche en Communication et Cybernétique de Nantes (IRCCyN), UMR 6597, sous la co-direction de MM. Jean-François Petiot (IRCCyN - Ecole Centrale de Nantes) et Andras Kemeny (RENAULT) et l'encadrement de M. Franck Mars (IRCCyN - CNRS).

Fenolinės rūgštys ir fenilpropanoidai pasižymi reikšmingu biologiniu aktyvumu ir yra vaistinių žaliavų veiklieji komponentai. Įteisintų tyrimo metodikų vystymas šių junginių nustatymui (kokybiniam ir kiekybiniam žaliavų tyrimui) yra ypač svarbus augalinių vaistinių preparatų efektyvumo, saugumo ir kokybės kontrolei. Iš skirtingų Lietuvos regionų buvo surinkta 18 propolio pavyzdžių. Atlikto darbo tikslas - analitiniais metodais ištirti Lietuvoje surinktų propolio pavyzdžių cheminę sudėtį, bei kiekybiškai ir kokybiškai įvertinti šias fenolines rūgštis ir fenilpropanoidus: chlorogeno rūgštį, cinamono rūgštį, galo rūgštį, ferulo rūgštį, kavos rūgštį, kumaro rūgštį, protokatecho (3,4-dihidroksibenzoinę) rūgštį, rozmarino rūgštį, vaniliną ir vanilino rūgštį. Atlikti tyrimai paprastos ir greitos atvirkštinių fazių efektyviosios skysčių chromatografijos metodikos optimizavimui ir įtiesinimui. Sukurto crhromatografinio metodo judrioji skystoji fazė yra metanolis ir 0,5 procento acto rūgšties tirpalas vandenyje. Esant optimalioms atskyrimo sąlygoms (aprašytoms skyriuje „Tyrimo metodas“), analizė atliekama 27 min., sulaikymo laikas 4,04 min (galo rūgštis), 6,93 min (protokatecho rūgštis), 11,30 min (chlorogeno rūgštis), 12,26 min (vanilinė rūgštis), 12,93 min (kavos rūgštis), 13,80 min (vanilinas), 16,97 min (kumaro rūgštis), 17,95 min (ferulo rūgštis), 22,29 min (rozmarino rūgštis) ir 26,30 min (cinamono rūgštis). Aptikimo riba ir nustatymo riba buvo atitinkamai tarp 0,004–0,021 ir 0,0... [toliau žr. visą tekstą] / The phenolic acids and phenylpropanoids have an important biological activity and are therapeutic agents of crude drugs. Development of validated analysis techniques of these phytotherapeutic agents (fingerprinting and assay procedures) is an important practice for efficacy, safety and quality control of herbal drug preparations. 18 samples of propolis were collected from different districts of Lithuania. The aim of the present work was to study chemical composition of collected samples and estimate analytical capabilities of the evaluation of selected phenolic acids and phenylpropanoids: caffeic acid, chlorogenic acid, cinnamic acid, coumaric acid, ferulic acid, gallic acid, protocatechuic (3,4-dihydroxybenzoic) acid, rosmarinic acid, vanillic acid and vanillin. Optimization and validation procedures of rapid and simple method of reversed phase high performance liquid chromatography were carried out. The mobile phase of the optimized chromatographic method consisted of methanol and 0.5 per cent acetic acid solvent in water. Under the optimal separation conditions (described in Methods), analysis was done in 27 min, with the retention times 4.04 min (gallic acid), 6.93 min (protocatechuic acid), 11.30 min (chlorogenic acid), 12.26 min (vanillic acid), 12.93 min (caffeic acid), 13.80 min (vanillin), 16.97 min (coumaric acid), 17.95 min (ferulic acid), 22.29 min (rosmarinic acid) and 26.30 min (cinnamic acid). The limits of detection and the limits of quantitation were between... [to full text]

Vaistinių augalinių žaliavų ir fitopreparatų antioksidantinio aktyvumo tyrimams būtina taikyti optimizuotus ESC pokolonėlinius metodus bei validuoti jų metodikas, kurios leistų patikimai, tiksliai bei atkartojamai įvertinti antioksidantų sudėtį, pasiskirstymą ir stabilumą. Darbo tikslas – nuodugniai ištirti ir pritaikyti ESC pokolonėlinius metodus augalinių antioksidantų tyrimams, augalinės žaliavos ekstraktų bei jų preparatų antioksidantų sudėties ir aktyvumo įvertinimui. Nustatyta, kad reakcijos kilpos parametrai turi įtakos smailės aukščio ir bazinės linijos triukšmo santykiui. Atliktų validacijos eksperimentų rezultatai patvirtina ESC-DPPH ir ESC-ABTS pokolonėlinių metodų tinkamumą radikalus surišančių junginių nustatymui ir kiekiniam antiradikalinio aktyvumo įvertinimui. Optimizuotas ESC-FRAP pokolonėlinis metodas tinkamas kompleksiniuose mišiniuose esančių junginių redukcinių savybių nustatymui ir kiekiniam redukcinio aktyvumo įvertinimui. Nustatyti pagrindiniai antiradikalinio ir/arba redukcinio aktyvumo žymenys: Crataegus L. – chlorogeno rūgštis ir hiperozidas; Origanum L. ir Perilla L. – rozmarino rūgštis; Achillea L. – chlorogeno rūgštis ir 3,5-dikafeoilchino rūgštis; Fragaria L. – epigalokatechino galatas. Šie žymenys tinkami antioksidantinius junginius kaupiančių vaistinių augalinių žaliavų bei fitopreparatų kokybės kontrolei. / A study of antioxidant activity in medicinal herbal raw materials and phytopreparations requires the application of optimized HPLC post-column assays as well as validation of their methodologies that could allow for a reliable, accurate and reproducible evaluation of composition, distribution and stability of antioxidants. The aim of the work is to examine HPLC post-column assays and adjust them for research on plant antioxidants as well as assessment of composition and activity of herbal raw material extracts and their preparations. It was determined that reaction coil parameters have impact on the ratio of peak height and baseline noise. Evaluated validation results confirm the suitability of HPLC-DPPH and HPLC-ABTS post-column assays for the determination of radical scavenging compounds and quantitative evaluation of antiradical activity. Optimized HPLC-FRAP post-column assay can be applied for discriminating reducing active compounds in complex mixtures and quantitative evaluation of their reducing activity. Main radical scavenging and/or reducing activity markers were determined: Chlorogenic acid and Hyperoside for Crataegus L., Rosmarinic acid for Origanum L. and Perilla L., Chlorogenic acid and 3,5-dicaffeoylquinic acid for Achillea L., Epigallocatechin gallate for Fragaria L. These markers are applicable for the quality control of the herbal raw materials and phytopreparations containing antioxidants.

A vast expansion is found in the field of automotive electronic systems. The expansion iscoupled with a related increase in the demands of power and design. Now, this is goodarena of engineering opportunities and challenges. One of the challenges faced, isdeveloping fault tolerant systems, which increases the overall automotive and passengersafety. The development in the field of automotive electronics has led to the innovationof some very sophisticated technology. However, with increasing sophistication intechnology also rises the requirement to develop fault tolerant solutions.As one of many steps towards developing a fault tolerant system, this thesis presents anexhaustive fault analysis. The modeling and fault analysis is carried out for a vehicle withfour in-wheel motors. The primary goal is to collect as many of the possible failuremodes that could occur in a vehicle. A database of possible failure modes is retrievedfrom the Vehicle Dynamics research group at KTH. Now with further inputs to thisdatabase the individual faults are factored with respect to change in parameters of vehicleperformance. The factored faults are grouped with respect to similar outputcharacterization.The fault groups are modeled and integrated into a vehicle model developed earlier inMatlab/Simulink. All the fault groups are simulated under specific conditions and theresults are obtained. The dynamic behavior of the vehicle under such fault conditions isanalyzed. Further, in particular the behavior of the vehicle with electronic stabilitycontrol (ESC) under the fault conditions is tested. The deviation in the vital vehicleperformance parameters from nominal is computed.Finally based on the results obtained, a ranking system termed Severity Ranking System(SeRS) is presented. The severity ranking is presented based on three essential vehicleperformance parameters, such as longitudinal acceleration ( ), lateral acceleration ( )and yaw rate ( ̇ ). The ranking of the faults are classified as low severity S1, mediumseverity S2, high severity S3 and very high severity S4. A fault tolerant system must beable to successfully detect the fault condition, isolate the fault and provide correctiveaction. Hence, this database would serve as an effective input in developing fault tolerantsystems.

Within many communities and religions, including the LDS community, there is some controversy surrounding the use of stem cells – particularly embryonic stem cells (ESC). Much of this controversy arises from confusion and misconceptions about what stem cells actually are, where they come from , and when life begins. The theology of the Church of Jesus Christ of Latter-day Saints has interesting implications for the last of these considerations, and it becomes less a question of “when does life begin” and more an exploration of “when does personhood begin” or “when does the spirit enter the body.” With no official Church stance, statements from Church leaders vary on this topic, and this first section of the thesis explores the philosophical and practical meaning of personhood with a biological background intended for those not familiar with the origin or uses of stem cells.The second portion of the thesis explores possible cloning technologies. Recent events and advances address the possibility of cloning endangered and extinct species. The ethics of these types of cloning have considerations uniquely different from the type of cloning commonly practiced. Cloning of cheetahs (and other endangered or vulnerable species) may be ethically appropriate, given certain constraints. However, the ethics of cloning extinct species varies; for example, cloning mammoths and Neanderthals is more ethically problematic than conservation cloning, and requires more attention. Cloning Neanderthals in particular is likely unethical and such a project should not be undertaken. It is important to discuss and plan for the constraints necessary to mitigate the harms of conservation and extinct cloning, and it is imperative that scientific and public discourse enlighten and guide actions in the sphere of cloning.

Small electric uninhabited aerial vehicles (UAV) represent a rapidly expanding market requiring optimization in both efficiency and weight; efficiency is critical during cruise or loiter where the vehicle operates at part power for up to 99% of the mission time. Of the four components (battery, motor, propeller, and electronic speed controller (ESC)) of the electric propulsion system used in small UAVs, the ESC has no accepted performance model and almost no published performance data. To collect performance data, instrumentation was developed to measure electrical power in and out of the ESC using the two wattmeter method and current sense resistors; data was collected with a differential simultaneous data acquisition system. Performance of the ESC was measured under different load, commanded throttle, bus voltage, and switching frequency, and it was found that ESC efficiency decreases with increasing torque and decreasing bus voltage and does not vary much with speed and switching frequency. The final instrumentation was limited to low-voltage systems and error propagation calculations indicate a great deal of error at low power measurements; despite these limitations, an understanding of ESC performance appropriate for conceptual design of these systems was obtained. MODELING AND TEST OF THE EFFICIENCY OF ELECTRONIC SPEED CONTROLLERS FOR BRUSHLESS DC MOTORS

As gender equality policies have gained more space in recent decades, the importance of gender-balanced corporate boards has also been widely debated. Large listed companies in Sweden have seen improvement in gender diversity in their boards in recent years, but the need for continued work towards gender equality remains a fact. There are various reasons to male-dominated boards, including norms, biases, and education, among others. The purpose of this thesis is to examine the statistical relationships between eight explanatory variables, and the dependent variable of the proportion of women on corporate boards. The approach for the analysis is through a panel data study, utilizing data from ten Swedish companies from the years 2015 to 2022, with support from principles of economics. The panel data using a random effect model, showed results where five out of eight explanatory variables were statistically significant. The variables market value, revenue, salary, and industry indicators L and M demonstrated a significant influence on the proportion of women on corporate boards. On the other hand, the variables ESG score and industry indicators C and G were found to be nonsignificant and therefore not suitable for inclusion in our model. However, the significant variables had small estimators, indicating a relatively small impact on the dependent variable. This may be explained by the number of observations in our analysis, which could have been increased and with a longer time span. / I takt med att jämställdhetspolitiken har fått mer utrymme de senaste decennierna har ävenvikten av jämställda bolagsstyrelser blivit omdiskuterad. Stora börsnoterade företag i Sverigehar under de senaste åren fått en bättre statistik kring könsfördelning i styrelser, men attfortsatt arbete krävs för jämställdhet är ett faktum. Det finns en rad olika anledningar tillmansdominerade styrelser. Normer, fördomar och utbildning bland annat. Syftet med dennauppsats är att titta på statistiska samband mellan åtta förklaringsvariabler ochberoendevariabeln andel kvinnor i bolagsstyrelser. Tillvägagångssättet för analysen ärpaneldata som tas från tio stycken svenska företags data mellan åren 2015-2022, med stöd avnationalekonomisk teori. Paneldatan där random effect model använts visade på ett resultat där fem av åttaförklaringsvariabler var signifikanta. Variablerna marknadsvärde, intäkter, lön,branschindikatorerna L och M visade en betydande påverkan på andel kvinnor ibolagsstyrelser. Däremot visade sig variablerna ESG-betyg, branschindikatorna C och G varaicke-signifikanta, och därmed inte vara passade i vår modell. Dock hade de signifikantavariablerna små estimatorer, det vill säga en relativt liten påverkan på beroendevariabeln.Detta kan vara på grund av antalet observationer som gjorts, som alltså skulle kunnat vara fleroch under en längre tidsperiod.