A RANS modelling approach for predicting powering performance of ships in waves

In this paper, a modelling technique for simulating self-propelled ships in waves is presented. The flow is modelled using a RANS solver coupled with an actuator disk model for the propeller. The motion of the ship is taken into consideration in the definition of the actuator disk region as well as the advance ratio of the propeller. The RPM of the propeller is controlled using a PID-controller with constraints added on the maximum permissible RPM increase rate. Results are presented for a freely surging model in regular waves with different constraints put on the PID-controller. The described method shows promising results and allows for the studying of several factors relating to selfpropulsion. However, more validation data is needed to judge the accuracy of the mode

Green ship technologies and kite assisted propulsion

Shipping is the key to international trade. Our aim should be to make it more environmentallyfriendly. The proliferation of 'green' legislation and heightened environmental expectationsgenerally have created new market opportunities and seen the emergence of technologicalsolutions that attempt to enhance the green profile of the shipping industry. This presentationwill discuss the opportunities that exist in the area of alternative sources of power and thepotential energy savings by design solutions. Reference will be made to the currenttechnology measures available and define the alternative sources of power that may beuseful for ship design. The second part of the presentation will discuss the current greenshipping technology outlook. Those are divided into technologies that may affect our industryover the short to medium term or over the long term. As a case study a brief analysis of theresults from a theoretical study into kite-assisted propulsion will be discussed

The use of a cap-mounted tri-axial accelerometer for measurement of distance, lap times and stroke rates in swim training

This paper will report some of the findings from a trial which recorded accelerometer data from six elite level swimmers (three female and three male, varying primary event stroke and distance) over the course of a regular 15 week training block. Measurements from a headmounted accelerometer are used to determine when the athlete is swimming, marking of turning points (and therefore distance and lap-time measurements), and is processed by frequency analysis to determine stroke-rate. Comparison with video where available, and with training plans and literature where not, have proven this method to be accurate and reliable for determining these performance metrics. The primary objective of this project was to develop a low-cost, simple and highly usable system for use in swim coaching, feedback from elite coaches has indicated that development of this could be an extremely useful addition to their training regime

IMPACT OF KINEMATIC MODIFICATION IN THE UNDERWATER UNDULATORY SWIMMING PERFORMANCE OF A SWIMMER

This work is a case study observing the impact of various kinematics modifications in the simulated pressure forces and hydrodynamic work done by an athlete performing maximum effort Underwater Undulatory Swimming (UUS). The studied athlete was recorded using a Motion Capture methodology. Seven key joints were identified to represent the athlete’s motion and their position were fitted with a fourth order Fourier series. This kinematic data was then modified to reduce or amplify the upper-body and lower-body motion but also to have a linear wave propagation. The kinematics (10 in total) were inputted in an unsteady 2D Computational Fluid Dynamics (CFD) solver, Lily Pad. Results suggest directions for improvement in the execution of the athlete’s swimming style, whether it is for reducing the hydrodynamic work done or minimising resistive forces

TWO AND THREE-DIMENSIONAL ASSESSMENTS OF LOWER-LIMB KINEMATICS IN UNDERWATER FLY KICK

The purpose of this study was to compare sagittal plane lower limb kinematics of underwater fly kick measured using two and three-dimensional methods. Eight male participants (average FINA points score 801±138) completed underwater fly kick trials, recorded using a six camera Qualisys underwater system. Each trial was analysed using both two and three-dimensional methods. Lower-limb angles were significantly underestimated using two-dimensional methods, particularly at the hip where flexion and range of motion reduced by 13.73 degrees and 15.91 degrees respectively. The ankle and hip produce a large amount motion in the transverse and frontal planes. The results of two-dimensional analyses of underwater fly kick should be interpreted with caution due reductions in measured angles, and exclusion of out-of-plane kinematic information

A synthesis of evidence for policy from behavioural science during COVID-19

Scientific evidence regularly guides policy decisions1, with behavioural science increasingly part of this process2. In April 2020, an influential paper3 proposed 19 policy recommendations (‘claims’) detailing how evidence from behavioural science could contribute to efforts to reduce impacts and end the COVID-19 pandemic. Here we assess 747 pandemic-related research articles that empirically investigated those claims. We report the scale of evidence and whether evidence supports them to indicate applicability for policymaking. Two independent teams, involving 72 reviewers, found evidence for 18 of 19 claims, with both teams finding evidence supporting 16 (89%) of those 18 claims. The strongest evidence supported claims that anticipated culture, polarization and misinformation would be associated with policy effectiveness. Claims suggesting trusted leaders and positive social norms increased adherence to behavioural interventions also had strong empirical support, as did appealing to social consensus or bipartisan agreement. Targeted language in messaging yielded mixed effects and there were no effects for highlighting individual benefits or protecting others. No available evidence existed to assess any distinct differences in effects between using the terms ‘physical distancing’ and ‘social distancing’. Analysis of 463 papers containing data showed generally large samples; 418 involved human participants with a mean of 16,848 (median of 1,699). That statistical power underscored improved suitability of behavioural science research for informing policy decisions. Furthermore, by implementing a standardized approach to evidence selection and synthesis, we amplify broader implications for advancing scientific evidence in policy formulation and prioritization

A synthesis of evidence for policy from behavioural science during COVID-19

Scientific evidence regularly guides policy decisions 1, with behavioural science increasingly part of this process 2. In April 2020, an influential paper 3 proposed 19 policy recommendations (‘claims’) detailing how evidence from behavioural science could contribute to efforts to reduce impacts and end the COVID-19 pandemic. Here we assess 747 pandemic-related research articles that empirically investigated those claims. We report the scale of evidence and whether evidence supports them to indicate applicability for policymaking. Two independent teams, involving 72 reviewers, found evidence for 18 of 19 claims, with both teams finding evidence supporting 16 (89%) of those 18 claims. The strongest evidence supported claims that anticipated culture, polarization and misinformation would be associated with policy effectiveness. Claims suggesting trusted leaders and positive social norms increased adherence to behavioural interventions also had strong empirical support, as did appealing to social consensus or bipartisan agreement. Targeted language in messaging yielded mixed effects and there were no effects for highlighting individual benefits or protecting others. No available evidence existed to assess any distinct differences in effects between using the terms ‘physical distancing’ and ‘social distancing’. Analysis of 463 papers containing data showed generally large samples; 418 involved human participants with a mean of 16,848 (median of 1,699). That statistical power underscored improved suitability of behavioural science research for informing policy decisions. Furthermore, by implementing a standardized approach to evidence selection and synthesis, we amplify broader implications for advancing scientific evidence in policy formulation and prioritization