Mémoire (M.Eng.)--Université du Québec à Chicoutimi, 1996. / Document électronique également accessible en format PDF. CaQCU

Thermocouples are one of the most commonly used instruments for thermometry at elevated  temperatures. As of today, there are only a few types of thermocouples that are built to withstand a temperature beyond 1600 °C,however they usually have a temperature measurement uncertainty of around 1% at these high temperatures. Beyond the 1600 °C temperature span, most high temperature thermocouples tend to drift in the measurements, causing it to output a faulty and inaccurate read of the actual temperature. This thesis explores the usage of carbon fibers as a material to be used in thermocouples, by the combination of two dissimilar carbon fibers. Polyacrylonitrile (PAN) and rayon based fibers were used up to a temperature of 200 °C, where the output voltage of the thermocouple was logged. The study shows a promising and stable linear output of the electromotive force for this type of thermocouple using commercially available carbon fibers at lower temperatures. A comparison is made between the commonly used thermocouples type K and S, results shows that the carbon thermocouple have around 21% of the thermoelectrical efficiency of that of a type K or S thermocouple at 25 °C. For the case of its functionality at higher temperatures, similar graphite material has been studied through literature and found a potential increase in the thermoelectrical stability at higher temperatures beyond 2000 °C, which show that carbon-based thermocouples are well suited for high temperature measurements. / Termoelement är ett av de mest använda instrumenten för temperaturavläsning vid upphöjda temperaturer. Idag finns det bara några få typer av termoelement som är byggda för temperaturer över 1600 ℃, däremot innehar dom vanligtvis en temperaturmätnings osäkerhet på cirka 1% vid dessa höga temperaturer. Över 1600 ℃ temperaturintervallet har de flesta högtemperatur termoelement en tendens att skifta i mätningarna vilket orsakar en felaktig och inexakt mätning av den faktiska temperaturen. Denna avhandling undersöker användningen av kolfiber som ett material för användning i termoelement, genom kombinationen av två olika grafitfibrer. Polyacrylonitrile- (PAN) och Rayon-baserade fibrer användes i en sammansatt kombination upp till en temperatur av 200 ℃, där spänningen mättes mot temperaturen. Studien visar en lovande och stabil linjär effekt av dess elektromotoriska spänning för denna typ av termoelement med kommersiellt tillgängliga kolfibrer vid lägre temperaturer. En jämförelse görs mellan de vanliga termoelementen av typ K och S vid rumstemperaturer, resultaten visar att grafittermoelementen har cirka 21% av den termoelektriska effektiviteten hos den för en typ K eller S termoelement vid 25 ℃. När det gäller dess funktionalitet vid högre temperaturer har liknande grafitmaterial studerats och funnit en potentiell ökning av den termoelektriska stabiliteten vid högre temperaturer över 2000 ℃, vilket visar att grafitbaserade termoelement gör sig väl lämpade för högtemperaturmätningar.

Mémoire (M.Eng.)--Université du Québec à Chicoutimi, 1995. / Résumé disponible sur Internet. CaQCU Document électronique également accessible en format PDF. CaQCU

Thèse(D.Eng.)-- Université du Québec à Chicoutimi, 2002. / Document électronique également accessible en format PDF. CaQCU

Thèse (M.Eng.) -- Université du Québec à Chicoutimi, 2003. / Bibliogr.: f. 66-73. Document électronique également accessible en format PDF. CaQCU

Highly selective and sensitive phosphate sensors have been fabricated by constructing a solid membrane disk consisting of variable mixtures of aluminium powder (Al), aluminium phosphate (AlPO4) and powdered copper (Cu). Both binary and ternary electrode systems are produced depending on their composition. The ternary membranes exhibit greater selectivity over a wide range of concentrations. The ternary electrode with the composition 25% AlPO4, 25% Cu and 50% Al was selected as our preferred electrode. The newly fabricated ternary membrane phosphate selective electrodes exhibited linear potential response in the concentration range of 1.0 × 10−6 to 1.0 × 10−1 mol L−1. The electrodes also exhibit a fast response time of <60 s. Their detection limit is 1.0 × 10−6 mol L−1. The unique feature of the described electrodes is their ability to maintain a steady and reproducible response in the absence of an ionic strength control. The electrodes have a long lifetime and can be stored in air when not in use. The selectivity of the new phosphate selective electrodes with respect to other common ions is excellent. The results obtained provide further insight into the working principles of the newly fabricated phosphate selective electrodes. Dephosphorylation and phosphorylation reactions were monitored using the preferred phosphate selective electrode. The following reactions were studied and inferences drawn; (a) the reactions between *[{CoN4(OH)(OH2)}]2+ and *[OH(PO2O)]2- for 1:1, 2:1 and 3:1 *[{CoN4(OH)(OH2)}]2+ to *[OH(PO2O)]2- ratios.(b) the reactions between *[{CoN4(OH)(OH2)}]2+ and *[O2NC6H4PO2(O)(OH)]- for 1:1, 2:1 and 3:1 *[{CoN4(OH)(OH2)}]2+ to *[O2NC6H4PO2(O)(OH)]- ratios. (c) the reactions between *[{CoN4(OH)(OH2)}]2+ and *[(OH)2(PO2)2O]2- for 1:1, 2:1 and 3:1 [{CoN4(OH)(OH2)}]2+ to *[(OH)2(PO2)2O]2- ratios, and (d) the reactions between *[{CoN4(OH)(OH2)}]2+ and *[(OH)2(PO2)3O2]3- for the 1:1, 2:1 and 3:1 [{CoN4(OH)(OH2)}]2+ to *[(OH)2(PO2)3O2]3- ratios. Further insight into dephosphorylation and phosphorylation reactions is unravelled by the novel phosphate selective electrode monitoring. *For clarity of the complexes utilized, see chapter 4, table 4.1. KEY WORDS; Dephosphorylation, phosphorylation, ion selective electrodes, phosphate ion selective electrode, decontamination, electromotive force, potential difference, activity, concentration, selectivity coefficient, calibration, ionic strength, hydrolysis, inorganic phosphates, nitrophenylphosphate, pyrophosphate, tripolyphosphate, organophosphate esters. / Chemistry / D.Phil (Chemistry)

Highly selective and sensitive phosphate sensors have been fabricated by constructing a solid membrane disk consisting of variable mixtures of aluminium powder (Al), aluminium phosphate (AlPO4) and powdered copper (Cu). Both binary and ternary electrode systems are produced depending on their composition. The ternary membranes exhibit greater selectivity over a wide range of concentrations. The ternary electrode with the composition 25% AlPO4, 25% Cu and 50% Al was selected as our preferred electrode. The newly fabricated ternary membrane phosphate selective electrodes exhibited linear potential response in the concentration range of 1.0 × 10−6 to 1.0 × 10−1 mol L−1. The electrodes also exhibit a fast response time of <60 s. Their detection limit is 1.0 × 10−6 mol L−1. The unique feature of the described electrodes is their ability to maintain a steady and reproducible response in the absence of an ionic strength control. The electrodes have a long lifetime and can be stored in air when not in use. The selectivity of the new phosphate selective electrodes with respect to other common ions is excellent. The results obtained provide further insight into the working principles of the newly fabricated phosphate selective electrodes. Dephosphorylation and phosphorylation reactions were monitored using the preferred phosphate selective electrode. The following reactions were studied and inferences drawn; (a) the reactions between *[{CoN4(OH)(OH2)}]2+ and *[OH(PO2O)]2- for 1:1, 2:1 and 3:1 *[{CoN4(OH)(OH2)}]2+ to *[OH(PO2O)]2- ratios.(b) the reactions between *[{CoN4(OH)(OH2)}]2+ and *[O2NC6H4PO2(O)(OH)]- for 1:1, 2:1 and 3:1 *[{CoN4(OH)(OH2)}]2+ to *[O2NC6H4PO2(O)(OH)]- ratios. (c) the reactions between *[{CoN4(OH)(OH2)}]2+ and *[(OH)2(PO2)2O]2- for 1:1, 2:1 and 3:1 [{CoN4(OH)(OH2)}]2+ to *[(OH)2(PO2)2O]2- ratios, and (d) the reactions between *[{CoN4(OH)(OH2)}]2+ and *[(OH)2(PO2)3O2]3- for the 1:1, 2:1 and 3:1 [{CoN4(OH)(OH2)}]2+ to *[(OH)2(PO2)3O2]3- ratios. Further insight into dephosphorylation and phosphorylation reactions is unravelled by the novel phosphate selective electrode monitoring. *For clarity of the complexes utilized, see chapter 4, table 4.1. KEY WORDS; Dephosphorylation, phosphorylation, ion selective electrodes, phosphate ion selective electrode, decontamination, electromotive force, potential difference, activity, concentration, selectivity coefficient, calibration, ionic strength, hydrolysis, inorganic phosphates, nitrophenylphosphate, pyrophosphate, tripolyphosphate, organophosphate esters. / Chemistry / D. Phil (Chemistry)

There is currently a high demand for electric power from renewablesources. One source that remains relatively untapped is the motionof ocean waves. Anders Hagnestål has been developing a uniquelyefficient and simplified design for a point-absorb buoy generator byconverting its linear motion directly into alternating electric power usinga linear PM engine. To test this method, a smaller prototype isbuilt. Its characteristics present some unusual challenges in the designand construction of its winding.Devices of this type typically use relatively low voltage (690V typicallyfor a wind turbine, compared to the 10kV range of traditionalpower plants). To achieve high power, they need high current, whichin turn requires splitting the conductors in the winding into isolatedparallel strands to avoid losses due to eddy currents and current crowding.However, new losses from circulating currents can then arise. Inorder to reduce said losses, the parallel conductors should be transposedin such a way that the aggregate electromotive force the circuitsthat each pair of them forms is minimized.This research and prototyping was performed in absence of advancedindustrial means of construction, with limited space, budget,materials, manpower, know-how, and technology. Manual ingenuityand empirical experimentation were required to find a practical implementationfor: laying the cables, fixing them in place, transferringthem to the machine, stripping their coating at the ends and establishinga reliable connection to the current source.Using theoretical derivations and FEM simulation, a sufficientlygood transposition scheme is proposed for the specific machine thatthe winding is built for. A bobbin replicating the shape of the enginecore is built to lay down the strands.The parallel strands are then organized each into their respectivebobbin, with a bobbin rack and conductor funneling device being designedand constructed to gather them together into a strictly-organizedbundle. An adhesive is found to set the cables in place.Problems with maintaining the orientation and configuration of thecables in the face of repeated torsion are met and solved. A chemicalsolution is used to strip the ends of the conductors, and a reliableconnection is established by crimping the conductors into a bi-metalCu-Al lug.ivIn conclusion, the ideal transposition schemes required to cancelout circulating currents due to magnetic flux leakage are impossibleto put in practice without appropriate technological means. The feasibletransposition scheme turns out to be a simple mirroring of conductors’positions, implemented by building each half of the windingseparately around replicas of the core and then connecting them usingcrimping lugs. / Efterfrågan på el från förnybara källor är hög och inget tyder på att det kommer ändras den närmsta tiden. En källa till förnybar el som än idag står relativt orörd är den där man använder energin från havsvå- gor. Det är denna förnybara källa Anders Hagnestål haft i åtanke när han nu bygger en unikt effektiv generator med syftet att i ett senare skede utvinna el med hjälp av flytande punktabsorberande vågkraft- system. Generatorn är av den linjära typen och omvandlar det punk- tabsorberande systemet rörelse till el. För att testa denna generator- modell så påbörjades bygget av två fullskaliga prototyper 2017. Denna uppsats behandlar specifikt arbetet med generatorlindningen till pro- totyperna och innefattar processen från design till själva byggnatio- nen. Lindingen består av flertalet mindre och isolerade lindningsleda- re med uppgift att bland annat minska skinneffekt och virvelströms- förluster. När man använder denna metod så uppkommer dock ett nytt problem vilket härstammar från att lindningsledarna är samman- kopplade i vardera ända och bildar på så sätt n slutna strömkretsar. Konsekvensen kan vara stora förluster från cirkulerande strömmar på grund av det magnetiska ströflöde som finns runt järnkärnan som lindningen omsluter. Utgångspunkten för att minimera dessa cirkule- rande strömmar är att transponera alla lindningsledare på ett sätt så att den resulterande elektromotoriska spänningen för varje strömkrets blir så liten som möjligt. Med hjälp av förenklade modeller samt FEM simuleringar så bestämdes ett lämpligt sätt att transponera lindningstrådarna utifrån oli- ka kriterier. Lösningen blev att lindningstrådarna endast transponera- des en gång med en så kallad 180 grader transponering. Detta ger en tillräckligt god minimering av de cirkulerande ström- marna, men den stora fördelen med denna lösning är att det är möjligt att linda maskinen med de små resurser projektet hade tillgång till, dock var detta till en stor nackdel då väldigt mycket tid gick till att hitta egna tillvägagångsätt för att utföra byggandet av lindningen på ibland okonventionella sätt.