Dirt ingress in hydraulic cylinders is one of the sources that leads to pollution of hydraulic systems. There are already several test rigs to investigate external contamination mechanisms. However, until now only the behavior of the whole sealing system was analyzed. A new testing method to understand the dirt particle transport between a reciprocating motioned rod and a wiper is presented. The new approach aims to avoid known issues such as limited reproducibility and long duration. The paper describes the test rig design and operating principle. First measurement results are shown.

The high frequency reciprocating rig (HFRR) is typically used to determine the lubricity of diesel fuels and has been accepted as the universal test apparatus in most countries of the world. A study was undertaken to analyse results obtained with the HFRR instrument by identifying crucial factors contributing to friction and wear mechanisms during a lubricity test under given conditions that may lead to a better understanding of test results obtained. The transient temperature distribution on a semiinfinite disk due to a circular continuous oscillatory heat source was also modelled. The model was used to calculate the contact temperature of a contact similar to what can be expected in the HFRR apparatus. For lubricated tests a mixture of n-hexadecane (cetane) as base fluid and palmitic acid as lubricity additive was used. Experimental results, including results obtained by running unlubricated (dry) tests and results obtained from literature were all considered to formulate the hypothesis that a fully functional additive film will not survive the full duration of the lubricity test, which is 75 minutes (ISO 12156-1, 2003). Friction values obtained in the experiments conducted were much higher than what is expected for boundary films formed by long chain carboxylic acids. Comparable friction values were obtained in the first few seconds of the tests, but the friction values increased indicating the destruction of the boundary film. Metal oxide lubrication dominates for the remainder of the test. Information of the exact mechanism prevailing in the crucial first few seconds of the test should be obtained by increasing the data acquisition rate of the apparatus. It is believed that junction growth through adhesion is the dominant factor in the initial stages of the test. GCxGC/TOF-MS showed the formation of hexane and heptane, which is a strong indication of the catalytic decomposition of the C16-hydrocarbons in the sample. / Dissertation (MEng)--University of Pretoria, 2010. / Chemical Engineering / unrestricted

Syftet med denna studie är att undersöka hur elever inom specialidrottsutbildningen med ishockey som inriktning, värderar sin elitsatsning i relation till sin studiegång. Utifrån en kvalitativ forskningsmetod har sex gymnasieelever intervjuats. Kodningen av intervjun skedde enligt Hjerm, Lindgren och Nilssons trestegsmetod. Sedan har materialet analyserats utifrån Stambulova, Engström, Franck, och Linnérs (2013) och Stambulova och Wyllemans (2015), holistiska idrottspsykologiska modeller för dubbla karriärer, som bygger på att hitta hållbara utvecklingsanpassningar för unga idrottare i deras strävan att nå eliten. Resultatet visar att eleverna i studien har tendenser till att planera kortsiktigt och inte se bortom horisonten på det som komma skall. Vissa av eleverna saknar även ett stödsystem i skolan, vilket påverkar dem negativt då fokus mellan elitsatsningen och studierna blir obalanserad. Vidare visar studien att ett starkt socialt stöd spelar en stor vikt i elevernas liv och motverkar skolans brister. Generellt har även resultaten från studien visat att det finns en viss skillnad i resonemangen hos elever som studerar sitt första år kontra de elever som är inne på år tre och sista terminen på gymnasiet. De elever som studerar sitt avslutande år på gymnasiet har börjat fundera mer på sin framtid efter utbildningen och vad den övergångsfasen kommer att innebära. Ishockeyn är inte en lika hög prioritering i vissa fall, och detta skapar en form av tomhet hos vissa respondenter. Eleverna som är i början på sin gymnasiekarriär visar däremot inga sådana tendenser utan är fullt fokuserade på att uppnå sina mål och har svårt att föreställa sig en alternativ karriär utanför ishockeyn.

One of the common failure modes in rolling contacts, such as in gears and rolling element bearings, is micropitting which has become a big issue. It is considered as a fatigue indicator and can lead to premature gear and bearing failure. This development work requires availability of a versatile test rig which reproduces the pitting or micropitting phenomenon under controlled conditions in the laboratory. The thesis has been carried out in the Department of Machine Design at KTH Royal Institute of Technology. It is a continuation of the project in the Advanced Machine Design course or Maskinkonstruktion högre kurs HK (in Swedish) as part of the Machine Design master programme at KTH. After specifying the scope and analyzing the challenges, this work deals with design modifications and further development of the previous test rig. All the problems addressed at the beginning have been solved. At the end, the newly assembled test rig indicates a stable, quieter and well performed working status as intended. The thesis work turns out a cost-effective way of developing micro-pitting test rig. Apart from physical deliverables; feasible solutions, recommendations and relevant documents such as specifications, program codes are provided in this paper. Some experience and thoughts during the project are also discussed in detail. Based on these, the mentioned future work can be performed and promoted to an advanced level. / En av de vanligaste typ av fel i rullande kontaktmekanik, såsom i kugghjul och kullager, är mikropitting. Fenomenet har nämligen blivit ett stort problem och betraktas som en tidig indikator för utmattning samt kan leda till tidiga utmattningsbrott i kugghjul och kullager. Detta utvecklingsarbete krävs en mångsidig testrigg som kan återskapa gropfrätning och mikropitting under kontrollerade förhållande I laboratorium. Denna examensarbete har genomförts inom Avdelningen för Maskinteknik vid Kungliga Tekniska Högskola (KTH). Arbetet utgör en vidareutveckling påett projekt för kursen ”Maskinkonstruktion högre kurs” inom maskindesignprogrammet. Utöver en analys av utmanningarna, det nuvarande arbetet presenterar designförändringar och vidareutveckling från det tidigare testriggen. Alla problem som påträffades har kunnat lösas. Till slut uppvisar den nymonterade testriggen alla förväntade egenskaper, nämligen stabilitet, förbättrad tysthet samt god performans. Den föreslagna metoden utgör därmed ett kostnadseffektivt sätt att utveckla testrigg för mikropitting. Arbetet består, utöver det fysiska produkten, av lösningar, rekommendationer och relevanta dokument såsom monteringsschema och programkod. En utförlig diskussion av tankar och erfarenheter från projektet presenteras. Baserat på dessa kan det nämnda arbetet genomföras och höjas till en advancerad nivå.

This study aimed to facilitate evaluation of alternative refrigerants for the air conditioner market. In order to achieve this target, two objectives were set. The first being the identification of alternative refrigerant with regard to regulations and trends. The second being enabling of thermodynamic evaluation of refrigerants for single components in air conditioners via design and installation of a test rig. A literature review was conducted to investigate the regulations, standards and trends for nine regions with high market shares. Furthermore, refrigerant substitutes for R410A and R22 where identified. The literature showed strong indications that a global HFC phase down is on the horizon, but that the approach and urge for such a phase down varies between regions where three main priorities could be seen; efficiency, GWP values and safety. Comparing these priorities with simulated refrigerant characteristics such as Carnot efficiency, GWP values, volumetric capacity and the liquid density using RefProp, identified alternatives. Further the literature showed that the lower flammability limit (LFL) and the amount of charge allowed were limiting factors for flammable refrigerant. There are many new refrigerants that could have less charge for the same capacity the LFL however restricts the refrigerants like R290, R441A and R443A only to be used in small systems. A test rig was designed and constructed in order to enable testing of single components in air conditioners. To verify the test rig, tests conducted with an evaporator using two refrigerants: R410A and R32. The reliability and validity of the tests was studied by comparing the results from the air side and refrigerant side, via uncertainty calculations using the GUM method and by a thermodynamic evaluation. The results of the repetition tests showed an expanded uncertainty, with a confidence interval of 95%, of 26 W for a cooling capacity of 2190W for R410A (Q̇evap,R410A=2190±26W). For R32 the expanded uncertainty was 27W for a cooling capacity of 2795W (Q̇evap,R32=2795±27W). Also the test rig was verified to be used for analyzing detailed evaluation of evaporators such as looking at heat transfer and the differential pressure drop. Further the study presented six conclusions: When evaluating refrigerants regional priorities between efficiency, safety and GWP values, refrigerant characteristics and type of unit need to be considered. Safety standards need to be more acceptable towards flammable refrigerants in order to meet low GWP targets. The change in market trends leads to new roles for the refrigerant and compressor suppliers and put higher demand on air conditioner manufacturers to consider refrigerant characteristics in product development. The importance of experimental thermodynamic evaluation on refrigerants effect on single components is increasing. Performance of different refrigerant for single components can be evaluated for optimizing cycle performance. Leapfrogging in the developing world can lead to a faster introduction of low GWP refrigerants.

This thesis project was done at Öhlins Racing AB, one of the world leading manufacturers of suspension equipment for motorcycles and race cars. A big part of that development is to collect and analyse data from tests done on fitted motorcycles and cars. How that is usually done is that a motorcycle is fitted with sensors and sent with a test driver around a track. Some adjustments are done on the suspension and then it's sent out again. This can be a very time-consuming process and the rider habits, weather changes and other uncontrollable effects can have a disrupting effect on the results making the tests practically unrepeatable. To be able to place a motorcycle in a controlled environment is therefore desirable to complement the track tests. Öhlins want to be able to use the shake-rig they already have at their facility in Jönköping for motorcycles as well as cars. It was the goal of this thesis project to take the first steps towards that happening. This report describes the process of designing such a support fixture. The goal of the thesis was to find a way to put a complete motorcycle (with rider) on a two post test-rig. This will require a contraption that prevents the motorcycle from falling off it. A comparative study was made with a simulation model to figure out which one of the concepts drawn up would perform the best. The winning concept was a telescopic swing-arm designed to extend from a mounting point on the motorcycle backwards to a foundation standing on the floor behind the bike. Considerable attention was paid to design a good connection to the motorcycle to which various types and makes of bikes could be mounted. The result was a support fixture made of almost exclusively aluminium with telescopic swing arms and a robust connection module to connect to a motorcycle’s peg-mount. The connection module can account for misalignment issues between the peg-mounts and with the use of washers and spacers it is fully adaptable to almost all sorts of bikes. / Detta examensarbete har utförts på Öhlins Racing AB, en av de världsledande tillverkarna av stötdämpare och hjulupphängningar för motorcyklar och racebilar. En stor del av utvecklingen är uppsamling och analys av testdata. Det utförs genom att man bestyckar en motorcykel med sensorer och skickar ut på en testbana. Sen ändrar man inställningar och upprepar testen. Det kan vara en tidskrävande process samtidigt som förarens vana, väder och andra okontrollerade element har avsevärd effekt på resultaten. Detta gör att tester som dessa är svårt att upprepa i praktiken och därför är det önskvärt att placera motorcykeln i en kontrollerad miljö för att komplementera bantesten. Öhlins vill ha möjlighet att använda skakriggen de har i deras anläggning i Jönköping för motorcyklar såväl som för bilar. Det var utmaningen i det här exjobbet att ta de första stegen åt det målet. Rapporten beskriver konstruktionsprocessen för en sådan fixtur. Målet med detta examensarbete var således att hitta ett lämpligt sätt att fixera en motorcykel och dess förare på en skakrigg. Det kräver en apparat som håller motorcykeln upprätt och inte tillåter att den ramlar av. En komparativ studie utfördes för att utvärdera vilket av framtagna koncept som skulle ge bäst resultat. Det valdes att fortsätta med ett koncept där en teleskopisk arm skulle sträckas bakåt från en kontaktpunkt på motorcykeln till ett fundament monterat på golvet bakom motorcykeln. En stor del av arbetet gick ut på att konstruera ett bra inkopplingssystem till motorcykeln mot vilket många olika varianter av motorcyklar kunde kopplas mot. Resultatet blev en fixtur bestående nästan enbart av aluminium, med teleskopiska armar och ett robust inkopplingssystem, kopplade mot motorcykelns fotpinnfästen. Modulen kan övervinna inriktningsproblem mellan fästen och med avståndsbrickor kan den vara kopplad till nästan alla sorters motorcyklar.

Industrial processes have for a long time become more and more automated, this is no different in the mining industry. When excavating during mining operations special drill rigs are used to drill holes in the rock walls to be used for either explosives or bolts to support the structure. The study aimed to find out if it was possible to create an algorithm that would use the drill rigs telemetry data to estimate the number of holes it had created over specific time period. The main approach would be to see if machine learning could be used for the problem or if some other method could be theorised. Without the groundwork needed to create a proper machine learning algorithm a basic statistical approach was used to solve the problem, however since there were no actual reports containing the amount of holes a rig drilled the final solution is highly conjectural.

No description available.

京都大学 / 0048 / 新制・論文博士 / 博士(生命科学) / 乙第12899号 / 論生博第11号 / 新制||生||43(附属図書館) / 31653 / 京都大学大学院生命科学研究科統合生命科学専攻 / (主査)教授 藤田 尚志, 教授 米原 伸, 教授 朝長 啓造 / 学位規則第4条第2項該当 / Doctor of Philosophy in Life Sciences / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(生命科学) / 甲第19907号 / 生博第354号 / 新制||生||47(附属図書館) / 32984 / 京都大学大学院生命科学研究科統合生命科学専攻 / (主査)教授 藤田 尚志, 教授 米原 伸, 教授 朝長 啓造 / 学位規則第4条第1項該当 / Doctor of Philosophy in Life Sciences / Kyoto University / DFAM