Friction of flat and micropatterned interfaces with nanoscale roughness

The dry friction of surfaces with nanoscale roughness and the possibility of using micropatterning to tailor friction by manipulating contact area is investigated. Square wave patterns produced on samples from silicon wafers (and their unstructured equivalent) were slid against unstructured silicon counter surfaces. The width of the square wave features was adjusted to vary the apparent feature contact area. The existence of nanoscale roughness was sufficient to ensure Amontons’ first law (F = μP) on both structured & unstructured samples. Somewhat counterintuitively, friction was independent of the apparent feature contact area making it difficult to tailor friction via the feature contact area. This occurred because, even though the apparent feature contact area was adjusted, the surface roughness and nominal flatness at the contact interface was preserved ensuring that the real contact area and thereby the friction, were likewise preserved. This is an interesting special case, but not universally applicable: friction can indeed be adjusted by structuring provided the intervention leads to a change in real contact area (or interlocking)– and this depends on the specific surface geometry and topography

Implementing ISO 14001 and Environmental Performance Evaluation: A Logistic Regression Model

Due to the growing popularity of environmental management systems and the ongoing debate among practitioners and researchers concerning the influence of environmental management systems on environmental performance, there is a need to assess how the implemented environmental management systems impact the environment. The current study examines the relationship between the guidelines provided by the ISO 14031 and ISO 14001 standards from three aspects, namely, utilizing information and data, planning for environmental performance and reviewing and improving environmental performance. This study will utilize a binary logistic regression to model and analyse the link between ISO 14001 and ISO 14031 using a 7-point Likert scale questionnaire. A total of 590 companies operating within the Saudi Arabia industrial sector were invited to take part in the study. The collection of data using questionnaires lasted from January to March 2019, and the results were analysed and compared with those of related studies. The model included a dependent variable representing whether the company is certified or not for ISO 14001 and 13 independent variables representing the main ISO 14031 guidelines. The research findings revealed that the developed model predicts 92.8% of the values, and the remaining 7.2% of the values are not covered. Thirteen independent variables were positively correlated with the dependent variable, indicating that the company is certified. The results of this study contribute significantly to the determination of the relationship between environmental performance and ISO 14001 certification

Publication practices in the Humanities: An in-depth case study of a Swedish Arts and Humanities Faculty 2010-2018

This paper is a case study of research publication practices at the Faculty of Arts and Humanities at Linnaeus University, a young, mid-sized university in the south-east of Sweden. Research output was measured from publications in the local institutional repository following the guidelines of local research policy as defined in university documentation. The data collection comprised 3,316 metadata records of publications self-registered by authors affiliated with the faculty during the period of 2010–2018. A statistical analysis of research output was conducted, focusing on preferred publication types, disciplinary specificity, level of co-authorship, and the language of the publication as registered in the local repository. The analysis focused on two main research questions: 1) how do the local research practices stand in relation to traditional publication patterns in the humanities? 2) how do the observed publication patterns relate to local university policy on publication and research evaluation? The empirical results suggest a limited correlation between publication practices and research incentives from university management, a finding that is corroborated by previous research on the scholarly character of the humanities and university policies. Overall, traditional humanities publication patterns were largely maintained throughout the period under investigation

High Temperature Corrosion Test of a Zirconium alloy

Department of Nuclear EngineeringThe possibility of breakaway oxidation of zirconium alloy cladding at high temperatures around 1000??C during small and large LOCA has been a concern in recent years. In March 2014, NRC proposed the revision of the ECCS acceptance criteria which breakaway oxidation was added to the previous criteria: the peak cladding temperature, cladding embrittlement, maximum hydrogen absorption, etc. in recent Federal Register. The standard, 10CFR50.46 which is proposed by NRC requires setting up the breakaway oxidation criterion based on actual performance of the fuel cladding and confirming the criterion by the periodic test of cladding tube which is used in the plant. High temperature oxidation of zirconium alloy has different trends with the low temperature oxidation because there are several differences between the low and high temperature oxidation. Because the oxidation depends on diffusion of oxygen, hydrogen, electron, and etc., oxidation rate is increased exponentially by increasing of oxidation temperature. Phase transformations of zirconium and their oxide are also concerned at high temperature; zirconium alloy can be received the distinctive phenomena by causing phase transformation. Zirconium alloy has a passivity of oxidation from the formation of dense oxide layer. The oxidation rate of zirconium alloy is reduced exponentially at first time. But when the zirconium oxide layer is changed into non-protective phase after some moment, oxidation kinetics is turned into linear or exponentially increased through the time. The transition of oxidation kinetics causes surface discoloration and this phenomenon is called as ???breakaway oxidation???. As mentioned before, the transition of oxidation kinetics is usually faster at higher temperature. But breakaway oxidation can be easily observed at certain points which are 800??C and 1000??C not at higher temperature. In order to simulate LOCA condition which is represented by the high temperature steam oxidation of rapidly heated cladding and subsequent quenching by water, a radiant heating system with the steam and water supply system are used for the test. A radiant heating system that used in the most of LOCA simulation tests, adopts the 4 or 6 line bulbs in order to achieve uniform heating in a circumferential direction. The verification of test equipment should be performed with the sequence of draft regulatory guide which is published by U.S NRC. Axial and circumferential temperature distribution is measured by a specimen with the welded thermocouples and the results of measurement are satisfied with the recommendation in the guide. The steam supply equipment is one of the important systems for the high temperature oxidation test because the high temperature oxidation test should be conducted in steam ambient. But the initial steam supply equipment has a problem which is unstable steam flow, so the new steam supply equipment was installed on the system. The new steam supply equipment don???t show any unstable steam flow and the steam generation rates of new steam supply equipment were measured by plate-type heat exchanger. The measurement of weight gain was performed and the results of measurement are compared with the well-established data of ZIRLO which was tested by Westinghouse and ANL. The results of ZIRLO weight gain measurement are consistent with the well-established data and these results are verified the high temperature oxidation test successfully. The microstructure of ZIRLO after the high temperature oxidation test is confirmed. At the first time, the microstructure of ZIRLO has flat interface between metal and oxide, but wavy metal / oxide interface can be observed in the picture after some moment. Wavy interface between metal and oxide is estimated to the precursor to breakaway oxidation phenomenon and the microstructure after the high temperature oxidation test is shown similar as the most of previous research. Thus, the successful test results are shown in the microstructure.ope

Sustainable Composites from Agricultural and Petroleum Waste

Green gas emission has been a pervasive and persistent subject of debate for a prolonged period. The soaring number of industries and vehicle fuel emissions presage a concomitant rise in global CO2 emissions. Global cement production is responsible for 8% of the total CO2 release, yet, the production continues due to the surging demand. Hence, there is an ongoing quest to find alternatives for cement and building materials produced with zero to lower CO2 emissions. The work presented in this dissertation focuses on finding recyclable, zero CO2 gas-producing high sulfur biocomposites materials, which can compete with the mechanical properties of commercial building materials like Portland cement. Chapter one describes the biopolymer substitution for commercially derived polymers. There is an emerging interest in substituting sustainable biopolymers fully or partially to the most commonly used commercial polymers. Lignin being the most abundant aromatic biopolymer, the tendency to use it as an alternative to commercial polymers is high-pitched. Technical issues associated with lignin incorporation and the impact of mechanical properties are specially discussed. Chapter two elaborates the preparation of sulfur crosslinked lignin composites through inverse vulcanization. The accomplishment of High Sulfur Materials (HSMs) with a biopolymeric agent to secure a stabilized network of sulfur is discussed. The mechanical, thermal properties, and mechanical integrity in recyclability are also examined. The work delivered in chapter three is about a new substrate development to access high sulfur materials as opposed to the traditional olefinic units in inverse vulcanization. The Radical induced Aryl halide Sulfur Polymerization (RASP) expands the substrate scope for high sulfur polymers. Two unmodified wastes – chlorolignin and sulfur were used as the most effective substrates to assess this concept. The materials’ thermal/mechanical properties and mechanical integrity over water absorption and harsh acidic conditions analogs to commercial building materials are discussed. The RASP can be employed with small molecules containing halide atoms. Chapter four presents the work performed with the small molecules to fabricate high sulfur polymers. A HSM was prepared by copolymerizing 81wt.% of elemental sulfur with a xylenol derivative to result in a composite wherein the sulfur is distributed between crosslinking chains and trapped free sulfur, which is not covalently bound. The mechanical properties of the same were compared to previous RASP polymers and the commercial building materials. Chapter five focuses on developing an easy route to make high sulfur polymers by employing organic molecules that generate radicals or radical reactive species via thermal degradation. Here, guaiacol ̶ a vast abundant lignin biopolymer precursor, and sulfur were directly reacted to form a stabilized matrix to retain polymeric sulfur. The microstructures analysis was done using NMR and GC-MS studies to identify possible mechanistic pathways

Sustainable utilisation of phosphorus within the dairy farm

According to the Dairy Australia Limited 2018, dairy is Australia’s 3rd largest rural industry. Also, fresh milk was sold for $2,242 million over 12 months (between February 2017 and January 2018) in Australian supermarkets. Thus, it is important to supply appropriate fodder for the milking cows through grazing pastures in dairy industries. Applying pond by-products produced by two-pond effluent treatment system, such as pond sludge, crust and effluent to the land (grazing paddock), has become a common method to enhance the recycling of nutrients within the dairy farm. This in turn yields several environmental benefits. Pond by-products provide nutrients for the plant growth and enhance the recycling of nutrients within the dairy farms. The recycling and reuse of pond by-products in dairy farms plays an essential role in the sustainable management of nutrients, particularly phosphorus (P). The purpose of this study was to investigate the variation in the P fractions contained in the pond by-products and soil treated with pond by-products within the dairy farms located in the Southern Highland dairy region, NSW, Australia. The study included three aspects: (i) identifying P fractions in various pond by-products; (ii) analysing P fractions in paddock soil treated with pond by-products; and (iii) conducting pot studies for assessing phosphorus use efficiency. This study indicated that the dairy pond sludge produced by the two-pond effluent treatment system contains significant amounts of plant available P, such as labile P and stable P. P fractionation analysis of the pond sludge showed that labile P and stable P in pond sludge was abundant with both being distributed evenly (50:50) compared to raw manure (stockpile, 80:20). The ratio of labile P and stable P is related to environmental effects on the soil and to plant growth upon land application. P fractionation of soil treated with pond sludge showed that land application of pond sludge increased all P fractions and improved soil fertility. Labile P and stable P increased by 30% and 45%, respectively, after pond sludge application. Additionally, paddocks treated with pond sludge had similar P distribution to the other paddock soil treated with other fertilisers simultaneously. The results of the pot experiment identified that ryegrass dry matter (DM) yield increased in soil treated with pond sludge. DM yield increased by 22% and 29%, respectively, in secondary pond sludge and primary pond sludge application pots compared to the control pots. Additionally, the soil applied with pond sludges was able to retain more water owing to the increased organic content. It was also found that all P fractions in soil treated with pond sludge increased at the end of the pot experiments. Potassium contained in the pond by-products in this study was relatively higher than in other studies. However, higher potassium in pond by-products did not increase grass tetany ratio in ryegrass. The distribution of the P fractions in pond sludge is affected by raw manure and pond treatment conditions. Additionally, environmental condition and P contents in pond by-products affect the distribution of P fractions in soil treated with pond sludge and effluent. Thus, the pre-analysis of the pond by-products and paddock soil is necessary to get an efficient pond sludge application rate before land application of pond sludge on the grazing paddock. Based on the findings, optimum pond sludge application rate can be determined using sequential fractionation. This in turn will help (i) to increase the dry matter yield of the grass; (ii) to reduce the potential loss of nutrient through runoff and leachate; and (iii) potentially replace the use of chemical fertiliser on dairy paddocks

Prospective Life Cycle Assessment in Surface Engineering: Case Studies on a Novel Thermal Spray Coating System and a Novel Coating Removal Method

Life Cycle Assessment (LCA) is a framework for quantifying the potential environmental impact of products from raw material extraction through materials processing, manufacturing, distribution, use, and end-of-life. Prospective LCA estimates the future environmental impacts of emerging technologies. It can be used to support eco-design, such as green surface engineering. Prospective LCA is used in this thesis to compare emerging surface engineering and incumbent technologies. The first case study compares a novel thermal sprayed multi-layered alumina-nickel chromium resistive heating coating to heat tracing cables for pipe freeze protection. The coating system’s impacts are higher for fabrication but lower for use, making it environmentally preferable in areas with colder climates and non-renewable electricity mixes. Specific life expectancy and efficiency improvements were identified to achieve environmentally preferability in most locations. Alternate strategies include reducing the environmental impact of fabrication by using alternate materials or deposition processes and developing strategies for recovering and recycling coating materials. The second case study compared a novel pulse water jet (PWJ) technology with alkaline electrochemical cleaning for removing hard chromium from aircraft landing gear. If the PWJ system can be designed to remove the coating from workpieces with complex geometry, its environmental impact is expected to be lower due to its lower electricity consumption, chemical use, and waste management. The case studies demonstrate the value of using prospective LCA during early development, adopting a range of techniques for addressing uncertainty, and breaking down the results to provide developers with strategies for reducing environmental impact

Contribution à la compréhension de la dynamique des rotors des alternateurs hydroélectriques

Dans les centrales hydrauliques, les groupes turbines-alternateurs sont soumis à plusieurs forces et couples dynamiques qui, sous certaines conditions, peuvent engendrer des bruits, des vibrations et des problèmes d’interactions avec le réseau, voire même des bris d’équipement. L’objectif de cette thèse est de développer un modèle d’alternateur hydroélectrique afin d’étudier les effets de la non-uniformité de l’entrefer et du défaut de court-circuit entre spires au rotor sur le comportement dynamique des groupes turbines-alternateurs. Les alternateurs hydroélectriques présentent toujours des entrefers non-uniformes. Ainsi, l’étude cherche à développer un modèle en utilisant la méthode des éléments finis et une mesure précise de l’entrefer sur un alternateur en en opération afin d’étudier les forces électromagnétiques qui pourraient exciter sa structure. Puisque l’entrefer est affecté par la dilatation thermique, les formes du stator et du rotor et le mouvement du rotor, cette modélisation numérique est nécessaire pour l’obtention d’un modèle réaliste du comportement du générateur. D’autre part, parmi les défauts les plus communs qui peuvent apparaître au rotor d’un alternateur hydroélectrique figure le défaut de court-circuit entre spires. Les courts-circuits d’enroulements de pôles amènent une augmentation significative des vibrations. Ces deux défauts jouent un rôle important dans le calcul des forces électromagnétiques. Le modèle permet d’étudier et d’évaluer plus précisément l’impact de ces défauts sur les forces électromagnétiques transmises à l’arbre. La présente thèse s’intéresse aussi aux modes et aux fréquences susceptibles d’entraîner des vibrations de la structure du stator à cause des excitations électromagnétiques résultantes des défauts mentionnés. Les transformées de Fourier rapides de la densité de force électromagnétique et de la force résultante totale révèlent l’existence des composants sous-harmoniques absents dans d’autres types de machines électriques. Ces sous-harmoniques causent des vibrations importantes sur l’arbre du groupe turbine-alternateur, ainsi que sur le stator et le rotor de l’alternateur. Les résultats expérimentaux confirment les résultats numériques et analytiques dans l’identification des spectres des forces. Dans le présent travail, l’analyse numérique apporte une contribution à l’étude du comportement dynamique des lignes d’arbres de groupes de production hydroélectriques, qui consiste en l’identification des harmoniques des défauts mentionnés, dans le cadre du projet SAMH (Simulations numériques appliquées aux machines hydrauliques) de l’Institut de recherche d’Hydro-Québec