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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Power output of America's Cup grinders can be improved with a biomechanical technique intervention

Pearson, Simon Unknown Date (has links)
Grinding set-up in America's Cup sailing provides the power behind tacking and gybing, where the yacht crosses the wind to change direction. Grinding is also used for trimming the sails, which changes the angle on which the yacht is headed. This study provided a descriptive biomechanical overview of grinding on an America's Cup class yacht, and experimentally evaluated the influence of technique instruction on backward grinding performance. Inter-subject differences in body position (technique) throughout the grinding cycle, the ability to alter grinding technique within an eight-day technique intervention period, and the effect of technique on grinding performance as determined by power output were assessed. The quasi-experimental design, in which each of eleven Team New Zealand America's Cup grinders served as their own control, assessed four trials of backward grinding at baseline and post-biomechanical technique intervention testing sessions. Each trial was a maximal effort performed against a high load (250 W) and sustained over a period of eight seconds. Sagittal plane video was used to analyse joint kinematics (elbow, shoulder, trunk, hip, knee, ankle angles and joint centre positions) and to calculate the centre of body mass relative to the grinder pedestal. Height, weight, and limb lengths were obtained from each grinder using the ISAK protocol. Current backward grinding technique employed by the majority of grinders did not optimally use biomechanical principles. Recommendations for improvement were specific to each individual but focused on lowering trunk position and distancing the trunk from the grinding pedestal. Real-time visual feedback was provided to the grinder operators with the main focus being the position of their hip joint (viewed in the sagittal plane), and lowering the shoulder to be vertically level with the apex of the grinding handle cycle. During the intervention the grinders were given added correctional instruction relating to their body position according to perceived technique requirements. Recommendations were based on biomechanical principles regarding body position, and how body position could be altered to optimise the contribution of body weight and force production by the muscles of the upper limb in order to improve the torque applied to the handles. Altering grinding technique according to biomechanical principles produced 4.7% (p = 0.012) greater power during five seconds of grinding performance. Muscular strength, when measured using a 1RM bench pull (116.4 ± 9.8 to 117.3 ± 10.3), was unaffected by the intervention program, thus not contributing to the increased power output observed during grinding. Moderate changes to body position were observed after the eight-day intervention. Forward lean of the trunk decreased from 25° to 17° (p = 0.028) due to a lower hipy position (-0.09 m to -0.16 m below hub, p = 0.019). The more vertical trunk alignment resulted in the shoulderx position being further from the hub (0.33 m to 0.41 m, p = 0.013), producing a greater line of pull due to a more efficient shoulder vector angle (47° to 36°, p = 0.009). Variability (standard deviation and confidence intervals) decreased in all but four kinematic measures (which exhibited no change) indicating improved consistency in grinding technique. Regression analysis indicated the best predictors for high-load backward grinding performance were COMx position relative to the grinding pedestal and maximal strength. Changes in COMx position explained 40% (p = 0.166) of the variation in grinding performance, while maximal strength showed a relationship of 0.23% (p = 0.144) increase in performance per kilogram of bench pull 1RM. A one standard deviation difference in maximal strength altered the effect of COMx position by 0.26% per centimetre (p = 0.008). Weaker predictive factors were body weight, standing height, and pull angle, while brachial index did not appear to have any substantial influence on backward grinding performance. For future research greater subject numbers should enable more conclusive findings, especially in terms of the technique mechanisms and their relative levels of influence on performance.
2

Power output of America's Cup grinders can be improved with a biomechanical technique intervention

Pearson, Simon Unknown Date (has links)
Grinding set-up in America's Cup sailing provides the power behind tacking and gybing, where the yacht crosses the wind to change direction. Grinding is also used for trimming the sails, which changes the angle on which the yacht is headed. This study provided a descriptive biomechanical overview of grinding on an America's Cup class yacht, and experimentally evaluated the influence of technique instruction on backward grinding performance. Inter-subject differences in body position (technique) throughout the grinding cycle, the ability to alter grinding technique within an eight-day technique intervention period, and the effect of technique on grinding performance as determined by power output were assessed. The quasi-experimental design, in which each of eleven Team New Zealand America's Cup grinders served as their own control, assessed four trials of backward grinding at baseline and post-biomechanical technique intervention testing sessions. Each trial was a maximal effort performed against a high load (250 W) and sustained over a period of eight seconds. Sagittal plane video was used to analyse joint kinematics (elbow, shoulder, trunk, hip, knee, ankle angles and joint centre positions) and to calculate the centre of body mass relative to the grinder pedestal. Height, weight, and limb lengths were obtained from each grinder using the ISAK protocol. Current backward grinding technique employed by the majority of grinders did not optimally use biomechanical principles. Recommendations for improvement were specific to each individual but focused on lowering trunk position and distancing the trunk from the grinding pedestal. Real-time visual feedback was provided to the grinder operators with the main focus being the position of their hip joint (viewed in the sagittal plane), and lowering the shoulder to be vertically level with the apex of the grinding handle cycle. During the intervention the grinders were given added correctional instruction relating to their body position according to perceived technique requirements. Recommendations were based on biomechanical principles regarding body position, and how body position could be altered to optimise the contribution of body weight and force production by the muscles of the upper limb in order to improve the torque applied to the handles. Altering grinding technique according to biomechanical principles produced 4.7% (p = 0.012) greater power during five seconds of grinding performance. Muscular strength, when measured using a 1RM bench pull (116.4 ± 9.8 to 117.3 ± 10.3), was unaffected by the intervention program, thus not contributing to the increased power output observed during grinding. Moderate changes to body position were observed after the eight-day intervention. Forward lean of the trunk decreased from 25° to 17° (p = 0.028) due to a lower hipy position (-0.09 m to -0.16 m below hub, p = 0.019). The more vertical trunk alignment resulted in the shoulderx position being further from the hub (0.33 m to 0.41 m, p = 0.013), producing a greater line of pull due to a more efficient shoulder vector angle (47° to 36°, p = 0.009). Variability (standard deviation and confidence intervals) decreased in all but four kinematic measures (which exhibited no change) indicating improved consistency in grinding technique. Regression analysis indicated the best predictors for high-load backward grinding performance were COMx position relative to the grinding pedestal and maximal strength. Changes in COMx position explained 40% (p = 0.166) of the variation in grinding performance, while maximal strength showed a relationship of 0.23% (p = 0.144) increase in performance per kilogram of bench pull 1RM. A one standard deviation difference in maximal strength altered the effect of COMx position by 0.26% per centimetre (p = 0.008). Weaker predictive factors were body weight, standing height, and pull angle, while brachial index did not appear to have any substantial influence on backward grinding performance. For future research greater subject numbers should enable more conclusive findings, especially in terms of the technique mechanisms and their relative levels of influence on performance.
3

OPTIMAL CONTROL OF THE AC75 SAILBOAT FOR THE AMERICA'S CUP RACE

Rodriguez Nunez, Renato January 2021 (has links)
This research focuses on the development of optimal sailing maneuvers for an AC75 foiling sailboat competing in the America's Cup. The America's Cup is the oldest, most prestigious, and technologically advanced sailboat racing competition in the world. Each iteration brings new and innovative sailboat designs which drastically improve sailing performance but increase complexity in the control of the sailboat system. This added complexity in the design and operation of the AC75 sailboat presents many challenges to the development of optimal sailing maneuvers. These challenges arise from the introduction of extra degrees of freedom and articulations in the boat such as the canting mechanisms (hydrofoils), which result in complex dynamical behaviors. The sailboat system is nonlinear, high-dimensional, and highly unstable. These complex characteristics require the development of high-order models, which are often intractable, or which introduce significant delays making them not well-suited for real-time control. The optimal maneuvers were achieved via the exploration of out-of-the-box solutions through data-driven controls and optimization. We used a high-fidelity sailboat simulator for the data generation process, and data-driven optimization schemes, such as Artificial Neural Networks (ANN), Extremum Seeking Control (ESC), and Jacobian Learning (JL) to optimize the sailing maneuvers. The optimizations were performed separately on various sailing maneuvers including close-hauled, tacking, and takeoff, as well as combinations of these maneuvers as performed during a race. The close-hauled and tacking maneuvers were optimized to achieve maximum Velocity Made Good (VMG) and minimum loss of VMG, respectively. The takeoff maneuver was optimized for maximum VMG and minimum time for the boat's transitions from displacement mode to foiling mode. The optimal solutions are subject to physical constraints and operational constraints enforced by the humans (sailors) in the loop. These maneuvers were developed for various heading angles (True Wind Angle (TWA)) and environmental conditions, such as True Wind Speed (TWS). Additionally, we performed an in-depth analysis of the optimal parameter settings obtained for close-hauled sailing to discern general trends in the parameter space. The trend of optimal parameters versus the wind direction provides a good understanding of the parameter space for varying sailing directions which can help guide the sailor's decisions during a race. The results show how optimization and controls can play a significant role in the development of advisory systems for complex human-operated systems. Lastly, the maneuvers developed in this search serve as performance benchmarks and provide insightful information about the underlying dynamics of the boat. / Mechanical Engineering
4

Commercialising national identity: a critical examination of New Zealand's America's Cup campaigns of 1987, 1992 and 1995

Evans, Bryn Unknown Date (has links)
This thesis analyses forms of New Zealand national identity constructed in conjunction with successive America's Cup campaigns in 1987, 1992 and 1995. It is argued that New Zealand national iconography was appropriated by government and corporate interests and utilised as a mechanism for corporate capital accumulation and legitimation.The first New Zealand challenge was set against a background of neo-liberal policy reform initiated by the fourth Labour government in 1984. The comprehensive economic and social policy implementation had multiple negative effects for New Zealand's political economy. This thesis undertakes a comprehensive analysis of these effects and argues that the commitment to neo-liberalism resulted in both the means for a New Zealand America's Cup syndicate and the necessity for an event which could obscure New Zealand's economic decline. National identity was reformulated through America's Cup nationalism to incorporate the values of neo-liberalism.As a result of the entrenchment of neo-liberal values, the needs of corporate interests and state enterprises to define citizens as consumers concluded in the commercialisation of culture. This thesis argues that the pursuit of effective corporate branding strategies led to the appropriation of symbols and images of national identity by corporate interests. The 1992 and 1995 America's Cup challenges represent the convergence of the discourses of sport, media and capitalism under the shared agenda of capital accumulation and legitimation. This convergence was structured around a commercialised conception of national identity which bore little relation to the social and economic reality experienced by many New Zealanders.
5

Mega sports event policy in Marseille 1991-2003 the football World Cup and the Americas Cup : a case study of urban governance

Cometti, Aurelie January 2007 (has links)
The aim of this thesis is to provide a theoretically informed account of the decision-making process in mega sports events policy in Marseille. This is intended to allow an evaluation of the major theoretical frameworks developed in the Anglo-Saxon literature on urban governance and their applicability to the French local government context, and more specifically to the context of sports policy in Marseille. Following an analysis of the development of the local political culture of Marseille, the thesis undertakes a review of theoretical frameworks developed in the urban policy literature identifying three major approaches / concepts which have dominated Anglo-Saxon literature, namely the growth coalition (Logan and Molotch 1987), policy network (Rhodes 1981; 1988), and urban regime (Stone 1989) approaches. These theoretical frameworks have been little used in French urban policy literature (Le Gales 1995; 2003) and feature rarely, if at all, in French sports policy literature. In reviewing this literature the thesis identifies a set of indicators, which may be used in empirical contexts to differentiate growth coalitions from policy networks and urban regimes. A major question for the research is thus to what extent Anglo-Saxon theoretical frameworks / concepts can be usefully employed to understand French decision-making and that of Marseille in particular. Subscribing to critical realism, the thesis aims to give an account of the mega sport event phenomena in Marseille, and of the actors' understanding and interpretation (in effect their social construction) of the phenomena. The data collected were documents for the period 1991 - 2003 from official sources (minutes and proceedings of local government and event-related bodies, reports, political speeches, and local government publications), local press coverage, and interviewees conducted with the major decision-makers. An ethnographic content analysis was made, partly employing a deductive approach based on the set of common indicators developed from the review of urban policy, and partly inductively from themes, which emerged in the analysis (Altheide 1996). The thesis concludes that while there is some evidence of the development of policy networks the specificity of the French context, and that of Marseille, with its heavily state-led approach to policy, means that the use of urban regime, and still less of growth coalition approaches, is not warranted by the evidence.
6

Commercialising national identity: a critical examination of New Zealand's America's Cup campaigns of 1987, 1992 and 1995

Evans, Bryn Unknown Date (has links)
This thesis analyses forms of New Zealand national identity constructed in conjunction with successive America's Cup campaigns in 1987, 1992 and 1995. It is argued that New Zealand national iconography was appropriated by government and corporate interests and utilised as a mechanism for corporate capital accumulation and legitimation.The first New Zealand challenge was set against a background of neo-liberal policy reform initiated by the fourth Labour government in 1984. The comprehensive economic and social policy implementation had multiple negative effects for New Zealand's political economy. This thesis undertakes a comprehensive analysis of these effects and argues that the commitment to neo-liberalism resulted in both the means for a New Zealand America's Cup syndicate and the necessity for an event which could obscure New Zealand's economic decline. National identity was reformulated through America's Cup nationalism to incorporate the values of neo-liberalism.As a result of the entrenchment of neo-liberal values, the needs of corporate interests and state enterprises to define citizens as consumers concluded in the commercialisation of culture. This thesis argues that the pursuit of effective corporate branding strategies led to the appropriation of symbols and images of national identity by corporate interests. The 1992 and 1995 America's Cup challenges represent the convergence of the discourses of sport, media and capitalism under the shared agenda of capital accumulation and legitimation. This convergence was structured around a commercialised conception of national identity which bore little relation to the social and economic reality experienced by many New Zealanders.

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