Experiments have shown that the addition of small amounts of long-chained polymer additives to a Newtonian fluid produces desirable lubricants. Additives added to oil make the fluid viscoelastic. The effect of viscoelasticity on lubrication characteristics has recently taken on added significance with the move to yet lower-viscosity lubricants for improved energy efficiency. Any factor influencing load-bearing capacity and wear is clearly of renewed importance. The general trend towards the usage of high performance lubricants and environmentally friendly products also support the design of new lubricants. This thesis is aimed at investigating viscoelastic flows within eccentric rotating cylinders (practical application - journal bearings) using a commercial finite element software POLYFLOW. Numerous validations are performed and excellent agreements are achieved. Steady shear and small-amplitude oscillatory shear (SAOS) experiments are performed for specific lubricants including mineral-based and bio-based lubricants to characterize their rheological behavior. Experimental data are fitted by a viscoelastic constitutive model used for numerical simulations. The effects of fluid viscoelasticity between eccentric rotating cylinders on the flow field and on the lubrication performances are revealed in 2D and 3D respectively. From 2D investigation, an increased load capacity on the inner cylinder is found to be achieved by increasing the viscoelasticity of flow. For the first time, to our knowledge, 3D results for an UCM (Upper-Convected Maxwell) fluid at steady state are presented and the flow patterns along the axial direction within the eccentric rotating cylinders are investigated. The viscoelastic effects of those lubricants on the journal bearing performances are revealed and compared at various temperatures. The modeling and numerical simulations used to predict the flow of lubricant in a journal bearing can generate important economic benefits. This research will lead to advanced predictive tools that can be used to improve the design of journal bearing and to propose new economically viable and environmentally friendly lubricants.

Experiments have shown that the addition of small amounts of long-chained polymer additives to a Newtonian fluid produces desirable lubricants. Additives added to oil make the fluid viscoelastic. The effect of viscoelasticity on lubrication characteristics has recently taken on added significance with the move to yet lower-viscosity lubricants for improved energy efficiency. Any factor influencing load-bearing capacity and wear is clearly of renewed importance. The general trend towards the usage of high performance lubricants and environmentally friendly products also support the design of new lubricants. This thesis is aimed at investigating viscoelastic flows within eccentric rotating cylinders (practical application - journal bearings) using a commercial finite element software POLYFLOW. Numerous validations are performed and excellent agreements are achieved. Steady shear and small-amplitude oscillatory shear (SAOS) experiments are performed for specific lubricants including mineral-based and bio-based lubricants to characterize their rheological behavior. Experimental data are fitted by a viscoelastic constitutive model used for numerical simulations. The effects of fluid viscoelasticity between eccentric rotating cylinders on the flow field and on the lubrication performances are revealed in 2D and 3D respectively. From 2D investigation, an increased load capacity on the inner cylinder is found to be achieved by increasing the viscoelasticity of flow. For the first time, to our knowledge, 3D results for an UCM (Upper-Convected Maxwell) fluid at steady state are presented and the flow patterns along the axial direction within the eccentric rotating cylinders are investigated. The viscoelastic effects of those lubricants on the journal bearing performances are revealed and compared at various temperatures. The modeling and numerical simulations used to predict the flow of lubricant in a journal bearing can generate important economic benefits. This research will lead to advanced predictive tools that can be used to improve the design of journal bearing and to propose new economically viable and environmentally friendly lubricants.

This biographical study accessed genealogical records, wills, probate records, and contemporary newspaper accounts to examine the lives of six generations of the middle-class merchant Dawbarn family of nineteenth-century Wisbech, Cambridgeshire and Liverpool. The purpose was to assess the extent to which the experiences of this Dissenter family, with a focus on third-generation businessman and author William Dawbarn (1819-1881), conform to the well-known story of the rise of the English middle class. The Dawbarns did conform to the commercial and social patterns established by the middle class: sons joined fathers’ businesses; religion was central to life; successful businessmen participated in local politics; membership in associations was common; and partible inheritance was the norm when passing wealth to the next generation. All of this was accomplished within a society which placed a high value on conformity. Yet a close reading of William Dawbarn’s writing reveals a benevolently eccentric individual. / Graduate

Experiments have shown that the addition of small amounts of long-chained polymer additives to a Newtonian fluid produces desirable lubricants. Additives added to oil make the fluid viscoelastic. The effect of viscoelasticity on lubrication characteristics has recently taken on added significance with the move to yet lower-viscosity lubricants for improved energy efficiency. Any factor influencing load-bearing capacity and wear is clearly of renewed importance. The general trend towards the usage of high performance lubricants and environmentally friendly products also support the design of new lubricants. This thesis is aimed at investigating viscoelastic flows within eccentric rotating cylinders (practical application - journal bearings) using a commercial finite element software POLYFLOW. Numerous validations are performed and excellent agreements are achieved. Steady shear and small-amplitude oscillatory shear (SAOS) experiments are performed for specific lubricants including mineral-based and bio-based lubricants to characterize their rheological behavior. Experimental data are fitted by a viscoelastic constitutive model used for numerical simulations. The effects of fluid viscoelasticity between eccentric rotating cylinders on the flow field and on the lubrication performances are revealed in 2D and 3D respectively. From 2D investigation, an increased load capacity on the inner cylinder is found to be achieved by increasing the viscoelasticity of flow. For the first time, to our knowledge, 3D results for an UCM (Upper-Convected Maxwell) fluid at steady state are presented and the flow patterns along the axial direction within the eccentric rotating cylinders are investigated. The viscoelastic effects of those lubricants on the journal bearing performances are revealed and compared at various temperatures. The modeling and numerical simulations used to predict the flow of lubricant in a journal bearing can generate important economic benefits. This research will lead to advanced predictive tools that can be used to improve the design of journal bearing and to propose new economically viable and environmentally friendly lubricants. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

No description available.

Purpose The purpose of this study was to describe the evidence-based research recommendations on injury prevention methods against hamstring injuries among Swedish men's elite team in football. The research-based recommendations was then to be compared with the way Swedish elite football teams work to prevent hamstrings injuries. Method First a literature search of PubMed and SPORTDiscuss was made to find the most evidence-based training methods to hamstring injuries. Then an Internet questionnaire regarding injury prevention training methods against hamstring injuries was sent to all Swedish elite football teams. The answers off the questionnaire was then compared with the research that had the most evidence based training methods to hamstring injuries. Results Research shows that the method with the most evidence is eccentric strength training. Flexibility, static stretch and core stability training is research methods that can be used to prevent hamstrings injuries but these methods lack a large validated research basis. 8 of 32 (25 %) teams answered the questionnaire. All teams indicated that they were working with injury prevention methods but the methods varied from the eccentric strength training to periodization and flexibility training. 2 of 8 teams indicated that they worked with eccentric strength training that is recommended by science as the most evidence-based training method. Conclusion The study shows that the teams partly work after what the research recommends as the most evidence-based training methods against hamstring injuries. However, the study lacks validity and further research is needed before definitive conclusions can be drawn. / Syfte Syftet med denna studie är att beskriva vilka evidensbaserade forskningsrekommendationer som finns kring skadeförebyggande träningsmetoder mot hamstringsskador hos svenska herrelitlag i fotboll. De forskningsbaserade rekommendationerna ska sedan jämföras med arbetssättet hos herrelitlagen i svensk fotboll. Metod Först gjordes en litteratursökning på databaserna PubMed och SPORTDiscuss för att hitta de mest evidensbaserade träningsmetoderna mot hamstringsskador. Sedan skickades en webbenkät angående skadeförebyggande träningsmetoder mot hamstringsskador ut till alla svenska herrelitfotbollslag. Svaren på enkäten speglades sedan mot vad forskningen rekommenderade som de mest effektiva träningsmetoderna mot hamstringsskador. Resultat Forskning visar att den metoden med mest evidens är excentrisk styrketräning. Rörelse/stretch samt bålstabilitetsträning är enligt forskningen metoder som kan användas för att förebygga hamstringsskador men dessa metoder saknar ett stort validerat forskningsunderlag. 8 av 32 (25%) föreningar besvarade enkäten. Alla föreningar angav att de arbetade med skadeförebyggande åtgärder men metoderna varierade från excentrisk styrketräning till periodisering och rörlighetsträning. 2 av 8 föreningar angav att de arbetade med excentrisk styrketräning som forskningen rekommenderar som den mest evidensbaserade träningsmetoden. Slutsats Studien visar att föreningarna delvis arbetar efter vad forskningen rekommenderar som evidensbaserade träningsmetoder mot hamstringsskador. Dock saknar studien validitet och ytterligare forskning behövs för att slutgiltiga slutsatser ska kunna dras.

No description available.

A robust, reliable method to non-invasively measure in-vivo mechanical properties of large tissue areas was unavailable until the advent of a new Magnetic Resonance Imaging (MRI) technique known as Magnetic Resonance Elastography (MRE). MRE is a phase-contrast imaging technique that enables quantification of tissue mechanical properties by capturing the motion of induced shear waves via a synchronised Motion Encoding Gradient (MEG). The complex shear modulus is determined via mathematical inversion and reported as the magnitude of the complex shear modulus, |G*|, and phase angle, φ. The work reported in this thesis focuses on the development of MRE data acquisition and analysis protocols optimised to study thigh muscle mechanical properties. The protocols are subsequently applied in healthy volunteers to study natural phenomena such as contraction and ageing and interventions such as an experimental protocol to produce Exercise Induced Muscle Damage (EIMD). Methodological advances made throughout this work include moving from 2D to 3D MRE data acquisition protocols and the application of advanced inversion software to extract muscle viscoelastic properties from the acquired MRE data. Results obtained include observation of reduced muscle stiffness in 6 elderly subjects (>80 years old) compared to 4 young subjects in the Vastus Lateralis (32%), quadriceps muscle group (22%) and entire thigh cross-section (19%), higher resting stiffness of agonist quadriceps compared to antagonist hamstrings (18%) and an increase in quadriceps stiffness (40%) during a leg raise task in 11 healthy subjects. Variability in muscle group recruitment patterns during the contraction were also observed, with the phase angle of the Vastus Intermedius (VI) increasing significantly during contraction. The final experiment involved the recruitment of 20 healthy male subjects to perform an eccentric exercise protocol designed to induce EIMD. Subjects who displayed a Maximum Voluntary Contraction (MVC) force deficit of >10% were considered to have experienced EIMD. A further severe EIMD group were defined based on the presence of hyper-intense signal on T2 weighted imaging following the protocol. The T2 hyper-intensity was found to occur exclusively in the Rectus Femoris (RF) and VI muscle groups. Increased muscle stiffness was observed in the RF muscle in subjects who experienced moderate EIMD (6%). A greater increase in RF stiffness (48%) was observed in the severe EIMD group. The severe EIMD group also displayed significantly increased VI stiffness (14%). The experiments carried out provide several novel findings which can support the development of beneficial strategies to promote both healthy ageing and rehabilitation in athletes, and potentially contribute to improving muscle performance evaluation tests which will expand the opportunities for clinical applications of muscle MRE.

It is now generally accepted that strength training in pubertal children will increase strength, but it is unlikely to induce morphological changes. However research in this area is limited as most studies fail to control for the confounding effects of normal growth, or employ appropriate training programs. To overcome these limitations it is suggested that researchers should use a within-subject design employing an exercise regime of sufficient intensity. In adults, eccentric training has been shown to have the greatest effect on hypertrophy and strength. The purpose of the study was to examine the effects of eccentric training on muscle strength and development in children, using a one arm training model. Seventeen boys in grades 6, 7, and 8 participated in an eight week eccentric elbow flexion training program; three training sessions per week. The program consisted of 2 5 sets of 6 10 reps using progressive resistance. Pre and post test strength (Eccentric and concentric elbow flexion maximal strength by a Biodex System 3 Dynamometer and 1 RM with dumbbells) and bicep thickness measurements were performed. The change in biceps thickness was significantly greater in the training arm versus the non-training arm (7.3 +/- 8.3% vs. 0.7 +/- 7.5%) (p<0.05). No significant difference was found for isokinetic concentric strength gain between arms (p>0.05), but isokinetic eccentric strength gain in the training arm was significantly greater than the non-training arm (25.4 +/- 16.6% vs. 2.4% +/- 15.6%) (p<0.05). Training arm 1 RM isotonic strength significantly increased when compared to the non-training arm, both concentrically (35.0 +/- 15.8% vs. 14.8 +/- 13.1%) and eccentrically (45.0 +/- 16.1% vs. 21.8 +/- 8.0%) (p<0.05). Results from this study indicate eccentric strength training can increase muscle strength and hypertrophy in pubertal boys.

It is now generally accepted that strength training in pubertal children will increase strength, but it is unlikely to induce morphological changes. However research in this area is limited as most studies fail to control for the confounding effects of normal growth, or employ appropriate training programs. To overcome these limitations it is suggested that researchers should use a within-subject design employing an exercise regime of sufficient intensity. In adults, eccentric training has been shown to have the greatest effect on hypertrophy and strength. The purpose of the study was to examine the effects of eccentric training on muscle strength and development in children, using a one arm training model. Seventeen boys in grades 6, 7, and 8 participated in an eight week eccentric elbow flexion training program; three training sessions per week. The program consisted of 2 5 sets of 6 10 reps using progressive resistance. Pre and post test strength (Eccentric and concentric elbow flexion maximal strength by a Biodex System 3 Dynamometer and 1 RM with dumbbells) and bicep thickness measurements were performed. The change in biceps thickness was significantly greater in the training arm versus the non-training arm (7.3 +/- 8.3% vs. 0.7 +/- 7.5%) (p<0.05). No significant difference was found for isokinetic concentric strength gain between arms (p>0.05), but isokinetic eccentric strength gain in the training arm was significantly greater than the non-training arm (25.4 +/- 16.6% vs. 2.4% +/- 15.6%) (p<0.05). Training arm 1 RM isotonic strength significantly increased when compared to the non-training arm, both concentrically (35.0 +/- 15.8% vs. 14.8 +/- 13.1%) and eccentrically (45.0 +/- 16.1% vs. 21.8 +/- 8.0%) (p<0.05). Results from this study indicate eccentric strength training can increase muscle strength and hypertrophy in pubertal boys.