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Exploration of Mechanical Properties of Enset–Sisal Hybrid Polymer Composite
No full textEnset and sisal fibers are among the most widely used reinforcement to fabricate natural fiber-based composite materials. Hand lay-up techniques were employed in this study to fabricate enset–sisal (E/S) hybrid fiber composite with volume ratios of 100/0, 75/25, 50/50, 25/75, and 0/100 and constant polyester resin. The tensile, flexural, impact strength, water absorption and morphological properties of the fabricated composite were investigated experimentally. The effects of hybridization to volume ratio were determined and the results show that hybrid composites excel in mechanical properties, compared with single composites. For better mechanical properties, the enset fiber has been hybridized with sisal fiber. Tensile and flexural strengths were enhanced by 47.3% and 41.03%, respectively, at 50/50 E/S volume ratio compared with 100/0 E/S composite. The impact strength of sisal fiber composite was improved by adding enset fiber in the composites. The inherent benefits and limitations of these two fibers were balanced out by each other in a positive way. While sisal fiber helped the composite intermesh of tensile, flexural, and reduction of water absorption, enset ensured impact strength. Morphological analysis was carried out in order to observe the fracture behavior and fiber pull-out of the samples by means of scanning electron microscopy
The Spatial Patterns of Student Mobility Before, During and After the Bologna Process in Germany
No full textThe paper contributes to the literature investigating students’ spatial mobility. By focusing on German higher education students with a novel dataset providing data from 1999 to 2015, we evaluate the impact of the change from a one-tiered to the two-tiered study structure of bachelor and master degrees (Bologna reform) on their inter-regional mobility and its underlying drivers. Our analysis confirms the system change to slightly alter inter-regional mobility of students. However, differences distinguish between different fields of study and universities und universities of applied sciences and indicate that the German higher education system is fairly resilient in its allocation of students. A Bologna-Drain of students moving from rural to urban regions to study master programs, can partially be confirmed for students of business studies. Our results reject the idea of (low) tuition fees discouraging students from enrolling in specific locations
Studie av sporelement i Nidelva, og om eventuell forureining kan relaterast til tidlegare og noverande drift ved St. Olavs Hospital
No full textDenne masteroppgåva er ein studie av sporelement i Nidelva som kan knytast opp mot tidlegare og noverande drift ved St. Olavs Hospital. Det vart teke vassprøver i 10 ulike punkt langs Nidelva, på seks ulike datoar. Prøvepunkta strekk seg frå Fossegrenda, og ned til Gangbrua ved Øya Stadion i Trondheim sentrum. Prøvepunkt 1 og 2, ved Fossegrenda og Sluppen-brua, vart brukt som referansepunkt, medan punkt 5 og 6 var rett nedanfor St. Olavs Hospital. Punkt 7-10 var nedstraums St. Olavs heilt ned til Øya Stadion, og punkt 3 og 4 var oppstraums St. Olavs. Hensikta med oppgåva er å sjå på sporelement-forureininga i Nidelva, og sjå om det kan knytast til St. Olavs som utsleppskjelde.
Vassprøvene vart tekne i perioden september-november i 2021, og alle prøvene vart analyserte med ICP-MS. Standardparameter som pH, turbiditet og leiingsevne vart også målt for alle prøvene.
Det vart funne at konsentrasjonane av fleire av sporelementa auka ved store nedbørsmengder. Likevel viste resultata at der ikkje var høge konsentrasjonar for nokon av sporelementa, og at Nidelva dermed ikkje er forureina på ein slik måte at det går ut over dyreliv og miljø.
Ved statistisk berekning vart det funne at for sporelement som kan knytast til sjukehusdrift, var forskjellen mellom konsentrasjonane i referansepunkta og konsentrasjonane i punkta rundt St. Olavs ikkje signifikant forskjellige. Det vart dermed funne at førekomsten av desse elementa ikkje direkte kan knytast opp mot drift ved sjukehuset, men ha andre moglege utsleppskjelder
Vedlikeholdsoptimalisering av korrosjon under isolasjon - En case-studie med bruk av empiriske data.
No full textDenne oppgaven har sett på muligheter for forbedring av vedlikeholdsstrategi knyttet til korrosjon under isolasjon. En Markov degraderingsmodell ble utviklet og benyttet for modellering av tilstandsutvikling og optimalisering av vedlikeholdsstrategier. Dette ble gjort ved å analysere empiriske data fra et prosessanlegg hvor Maintech gjennomfører risikobasert inspeksjon av korrosjon under isolasjon. Disse dataene ble så supplert med litteratur, praktisk kunnskap og kvalitativ informasjon fra Equinor, Axess og Maintech. Dette ble videre benyttet for å modellere ulike vedlikeholdsstrategier knyttet til korrosjon under isolasjon.
Enkelte antagelser ble gjort for å få en modell tilpasset virkeligheten. Blant annet måtte inspeksjonsmatrisen inkluderes på en suboptimal måte. Modellen ble videre brukt til å modellere ulike vedlikeholdsstratergier. Dette ble gjort fra et kostnadsperspektiv, med hensyn til potensialet for lekkasjer.
Markov-modellen fungerte som tiltenkt, og ga klare resultater for strategiene som ble modellert. Resultatene indikerer at det vil være potensiale for forbedring av vedlikeholsstrategien knyttet til korrosjon under isolasjon. Kostnader hadde en sentral rolle i modelleringen.
Resultatene for kostnader viste at i et kortsiktig perspektiv så vil inspeksjonskostnader være dominerende, men i et langsiktig perspektiv vil reparasjoner, eventuelle produksjonstap og ulykker være den dominerende kostnadsposten.
Resultatene viste at vedlikeholdsstrategier bør ses på i et langsiktig perspektiv, og tilpasses anleggets tiltenkte levealder. Data bør også samles inn systematisk gjennom hele anleggets levealder. Modellen viste gode evner for modellering, men vil ha behov for videre validering og tilpasninger for ytterligere forbedringer
Nanoscale creep behavior and its size dependency of a Zr-based bulk metallic glass manufactured by selective laser melting
No full textNanoscale creep behaviors of metallic glasses (MGs) have gathered considerable interests in recent years, owing to their distinct atomistic mechanisms of plasticity. Additive manufacturing (AM) is a burgeoning technique for manufacturing MGs, the nanoscale creep characteristics and creep mechanism of the AM-ed MGs, however, remain ambiguous. In this work, the nanoscale creep behavior and creep size effect of a selective laser melted (SLM-ed) Zr-based MG were investigated by using nanoindentation. In an effort to gain more insight into the creep behaviors, the creep compliance and creep retardation spectra were extracted. The creep stress exponent (n) and shear transformation zone (STZ) volume, as the indicators of the creep mechanism, were estimated. The values of n are in the range of 2-3, and STZ volumes are around 2 nm3. The creep resistance of the MG was found to decrease with the increasing applied peak loads. A potential mechanism for this creep size effect was revealed: the smaller of the STZ volume, as well as the greater ratio of plastic flow under the higher maximum load, are responsible for the decreasing tendency of creep resistance. This research gives a comprehensive understanding of the atomistic mechanisms in the AM-ed MG during the nanoscale creep deformation process and can serve as a reference for improving the plasticity and further engineering applications
Health and diseases of semi-domesticated reindeer in a climate change perspective
No full textClimate change may affect reindeer herding and the health and disease of reindeer in several ways. One way of mitigating such changes is supplementary feeding, both in corrals and by bringing fodder to the animals on natural pastures. Feeding, when the right feed and feeding regime are used, may compensate for the loss of natural pastures and increase animal welfare. However, feeding may also cause issues with health and disease. These challenges may be associated with the feed and feeding regimes themselves, but also indirectly, by creating increased animal-to-animal contact and through the difficulty of maintaining hygienic conditions in corrals. In addition, climate change may have an impact on the presence of arthropod species and populations, such as ticks, mosquitoes and midges. These insects may cause increased levels of stress for the animals but can also be vectors for pathogens that may cause severe disease outbreaks, animal welfare issues and economic loss for reindeer herders. This chapter briefly presents the diseases and health problems that are directly or indirectly associated with reindeer feeding, as well as health challenges associated with arthropods and vector-borne diseases that are expected to be affected by climate change in the Arctic and sub-Arctic regions
Topology Optimization in Mechanical Engineering: Implementation and practical aspects
No full textOne of the most applied optimization methods in mechanical engineering is topology optimization (TO). The benefits of its integration in the product development process are several, such as reducing material usage in manufacturing, shortening the design cycle, and enhancing product quality. However, the implementation of TO is characterized by the following bottlenecks: the geometrical complexity of its optimized designs, the long optimization times, the sensitivity of its results to the given parameters, and the need for numerous inputs during its workflow. All these issues make TO a complex and time-demanding procedure dependent on designers’ starting guesses and choices during its implementation. It is clear that there is a need for a more automatic and effective optimization procedure.
In this thesis, the author uses TO for the weight reduction of structures in mechanical engineering. First, he explores the workflow of the TO and identifies interesting practical aspects in its implementation. The most popular TO-methods, such as SIMP and BESO, are described, categorized, and compared. In addition, the three following TO-practices are developed with respect to the size of the available design space for optimization: TO with limited design space, TO with maximum possible design space, and combined size/shape/topology optimization. The author states that the designer’s choices (inputs) affect the TO-results and categorizes them into five clusters of parameters: design constraints, supports and connections, loads, geometric restrictions due to manufacturing constraints, and software constraints. The sensitivity of the TO-results to the variations of these parameters is explored.
Furthermore, different multi-objective, multi-level, and multi-scale optimization workflows are used in the pursuit of the lightest design solutions. To identify the software constraints, a literature review is conducted among the most applied TO-software platforms. As a result, an online library of 70 commercial and open source TO software is developed in the form of a table. This table encompasses the name, company, optimization types, and methods that software uses, as well as its available objective functions and constraints in TO. Moreover, relative research works and representative literature for each software are included. Different 3D models are designed, optimized, and used as case studies to support the theory and tie the academic text to real-world applications of TO. Finally, the educational perspective of TO is checked. The author developed an educational framework of a topology optimization-based learning (TOBL) combining the CDIO-approach and TO. The implementation of the developed TOBL-framework in any study program in CAD-engineering can educate modern CAD-designers to conceive, design, implement, and operate optimized products.
The current research work is addressed to practitioners, researchers, teachers, and other engineers looking for new lightweight design concepts. Hence, the aim of this thesis is to provide them, through valuable insights, with a better understanding of TO, as well as to advise them with guidelines and recommendations to avoid common pitfalls
Foucault’s archeological discourse analysis with digital methodology—Discourse on women prior to the first wave women’s movement
No full textIn L’archéologie du savoir (1969), Foucault specifies the method of discourse analysis as the identification of statements. Few digital humanities projects have set out to conduct discourse analysis in this tradition. A certain degree of confusion relates to what the Foucauldian statement consists of and how it can be operationalized in order to identify discourse, using digital methods. This article demonstrates, however, that such an operationalization becomes possible if we take Foucault’s own distinction between statement (énoncé) and enunciation (énonciation) into account. As an example, the article shows how discourse on women prior to the first wave women’s movement in Western countries has been identified in almost 7,000 books digitized by the Norwegian National Library. This article concludes that a digitized Foucauldian discourse analysis is possible, using a combination of digital methodology and close reading
The teleost polymeric Ig receptor counterpart in ballan wrasse (Labrus bergylta) differs from pIgR in higher vertebrates
No full textAs mucosal barriers in fish are the main sites where pathogens are encountered, mucosal immunity is crucial to avoid infection in the aquatic environment. In teleost fish, immunoglobulins are present in gut, gill and skin mucus, although not in the same amounts as in higher vertebrates. In mammals, the poly-Ig receptor (pIgR) is synthesized in epithelial cells and mediates the active transport of poly-immunoglobulins (pIgs) across the epithelium. During transport, a component of the pIgR, the secretory component (SC), is covalently bound to pIgs secreted into the mucus providing protection against proteases and avoiding degradation. The teleost pIgR gene does not show synteny to higher vertebrates, the overall structure of the protein is different (comprising two Ig domains) and its functional mechanisms remain unclear. The J-chain which is essential for pIgR-mediated transport of IgA and IgM in higher vertebrates is absent in teleost fish. The aim of the present study was to characterize the ballan wrasse (Labrus bergylta) pIgR and use it as a marker for further studies of mucosal immunity in this species. The pIgR gene was unambiguously identified. Unexpectedly, reverse transcription real time PCR (RT-qPCR) revealed highest abundance of pIgR mRNA in liver and significantly lower expression in mucosal organs such as foregut, hindgut, and skin. In situ hybridization showed pIgR-positive cells dispersed in the lamina propria while it was undetectable in epithelial cells of foregut and hindgut of ballan wrasse. A similar pattern was observed in Atlantic salmon. Liquid Chromatography-Mass Spectrometry (LC-MS/MS) analysis of IgM enriched mucus samples from gut, gill, skin, and bile gave relatively few matches to wrasse pIgR. Notably, the matching peptides were from the transmembrane (TM) and cytoplasmatic (Cy) region as well as the putative SC, indicating leakage from lysed cells rather than covalent bonds between IgM and SC. Altogether, the results indicate that pIgR has another (or at least an additional) function in wrasse. Another pIgR-like molecule (pIgRL) in ballan wrasse (comprising three Ig domains) was analyzed to see if this could be an alternative functional pIgR homolog. However, the presence of pIgRL mRNA in blood leukocytes and a relatively high expression in immune organs like spleen and head kidney pointed to a receptor function on a circulating leukocyte population. As significant amounts of IgM were found in bile of ballan wrasse further studies should consider the hepato-biliary route regarding IgM delivery to the gut lumen
Financial risk of road traffic trauma care in public and private hospitals in Addis Ababa, Ethiopia: A cross-sectional observational study
No full textBackground
Road traffic injuries are among the most important causes of morbidity and mortality and cause substantial economic loss to households in Ethiopia. This study estimates the financial risks of seeking trauma care due to road traffic injuries in Addis Ababa, Ethiopia.
Methods
This is a cross-sectional survey on out-of-pocket (OOP) expenditures related to trauma care in three public and one private hospital in Addis Ababa from December 2018 to February 2019. Direct medical and non-medical costs (2018 USD) were collected from 452 trauma cases. Catastrophic health expenditures were defined as OOP health expenditures of 10% or more of total household expenditures. Additionally, we investigated the impoverishment effect of OOP expenditures using the international poverty line of 256 for outpatient visits and 96 and $68 per patient, respectively.
Conclusion
Seeking trauma care after a road traffic injury poses a substantial financial threat to Ethiopian households due to lack of strong financial risk protection mechanisms. Ethiopia's government should enact multisectoral interventions for increasing the prevention of road traffic injuries and implement universal public finance of trauma care