199 research outputs found
Sports engineering : comparison of blade designs in traditional paddle sports
No full textThe objective of conducting this study is to analyze the effect of blade geometry on the rowing efficiency for paddles used in both traditional and popular paddling sports. This was achieved through a deep understanding of how a paddle works and applying the concepts of fluid dynamics, particularly in the fields of drag and pressure. The author selected a Macon paddle, which incorporates a design derived by technological means, and compared it against the dragon boat and Royal Thai Barge paddles, which represented the traditional boating equipment. A rectangular paddle blade was added to further enhance the study.
The author adopted a two-pronged approach to the study. The first component was a computational fluid dynamics study using two commercial programs. GAMBIT was used to model the paddle in a water tank and to define the experiment’s parameters, while FLUENT acted as the solver that ran the simulation and produced the relevant results. The author opted to operate at laminar flow conditions with an initial fluid velocity of 0.5 m/s. The second aspect of the study involved a water tunnel experiment, using a 3-component balance system, in which scaled models of the four paddles, in the scale of 1:4, were placed perpendicularly to the flow to determine the drag force. The author elected to operate at four different speeds (0.1 m/s, 0.18 m/s, 0.28 m/s and 0.37 m/s) and conducted five runs for each paddle blade. The water tunnel tests were conducted to validate the findings from the CFD simulation.
The computational fluid dynamics simulations proved that the Macon paddle was the most effective paddle blade design. It had the highest drag coefficient amongst the four paddles. Subsequent calculations showed that it generated the highest drag force. The Macon paddle also yielded the largest pressure readings on its surface. More significantly, the flow profile around the paddle revealed greater turbulence, due to the formation of a swirling pool in its wake. This phenomena is absent in the other paddles, indicating the Macon paddle’s effectiveness in disrupting flow and generating drag. On the contrary, the Royal Thai Barge paddle was least efficient, while the rectangular paddle and dragon boat paddle had comparable results due to similar geometry.
The water tunnel experiments showed that the rectangular blade provided the best drag force at low speeds, while the Macon was best at 0.28 m/s and the Royal Thai Barge was most effective at 0.37 m/s. The relationship between drag coefficient and Reynold’s number was also deduced, proving that the curvature of the paddles enhanced the drag coefficient values when compared against a regular flat plate. The experiments also established that the Macon generated the highest turbulent flow. Although this meant that it was likely to produce the least pressure drag due to delayed flow separation, the Macon actually produced a drag coefficient of 1.7, which is almost equal to the other paddle designs. Additionally, dimensional analysis was conducted to calculate the coefficient of drags for each paddle blade at a Reynold’s number of 2500. It was discovered that the Macon paddle produced the highest drag coefficient, while the Royal Thai Barge paddle had the least value.
It can be concluded that the Macon paddle is the most effective paddle blade design, as it is capable of producing the highest drag coefficient, which is beneficial to a paddler as it reduces the work done in operating the paddle. This highlights the significance of sports engineering in developing better performing equipment in the pursuit of sporting excellence. Although the author appreciates the importance of traditional paddle blade designs in preserving culture, the author recognizes the role science and technology plays in shaping the equipment used in sports.Bachelor of Engineering (Mechanical Engineering
Self-detecting gate-tunable nanotube paddle resonators
No full textWe have fabricated suspended metal paddle resonators with carbon nanotubes functioning as self-detecting torsional springs. We observe gate-tunable resonances that either tune to higher or to lower frequencies when increasing the dc voltage on the back gate. We attribute the former modes to flexural vibrations of the paddle resonator, while the latter ones are identified as torsional vibrations. Compared to top-down silicon fabricated paddle resonators, nanotube springs have smaller torsional spring constants and provide a larger frequency tunability.Kavli Institute of NanoscienceApplied Science
Parametric Analysis of a Double Shaft, Batch-Type Paddle Mixer Using the Discrete Element Method (DEM)
No full textTo improve the understanding of the mixing performance of double shaft, batch-type paddle mixers, the discrete element method (DEM) in combination with a Plackett–Burman design of experiments simulation plan is used to identify factor significance on the system’s mixing performance. Effects of several factors, including three material properties (particle size, particle density and composition), three operational conditions (initial filling pattern, fill level and impeller rotational speed) and three geometric parameters (paddle size, paddle angle and paddle number), were quantitatively investigated using the relative standard deviation (RSD). Four key performance indicators (KPIs), namely the mixing quality, mixing time, average mixing power and energy required to reach a steady state, were defined to evaluate the performance of the double paddle mixer. The results show that the material property effects are not as significant as those of the operational conditions and geometric parameters. In particular, the geometric parameters were observed to significantly influence the energy consumption, while not affecting the mixing quality and mixing time, showing their potential towards designing more sustainable mixers. Furthermore, the analysis of granular temperature revealed that the centre area between the two paddles has a high diffusivity, which can be correlated to the mixing time
Australian multi-center experience outside of the Sydney Melanoma Unit of isolated limb infusion chemotherapy for melanoma
No full textArticle first published online: 15 MAR 2014Abstract not availableBrendon J. Coventry, Hidde M. Kroon, Mitchell H. Giles, Michael Henderson, David Speakman, Mark Wall, Andrew Barbour, Jonathan Serpell, Paul Paddle, Alexander G.J. Coventry, Thomas Sullivan, and B. Mark Smither
Analyzing Internal Stresses in a Dragon Boat Paddle to Optimize First Stroke Technique
No full textabstract: The objective of this experiment was to investigate the correlation between the starting pitch angle of a Dragon Boat paddle and the ensuing total stress and force on the paddle during the first stroke. During the first stroke (i.e., starting at rest) the stress on the paddle can be equated with the force output. To do this, a paddle was modified with a strain gauge and other equipment, and tests were run varying the pitch angle. The results showed that while the most positive starting angle yielded the highest stress and force on the paddle, there was no discernible trend correlating the angle to the stress. Further experimentation must be run to determine which other factors influence the stress. (abstract
Neuromechanical Control of Paddle Juggling
No full textThe objective of this research is to discover the rules by which the human nervous system controls the cyclic task of paddle juggling. The existence of separate feedforward and feedback control signals is hypothesized, and the feedforward control system is completely identified using tools from dynamical systems theory. Using this knowledge progress is made in identifying the feedback control system, with some interesting findings. The author believes that the data analysis methods in this work are novel and can be applied in the study of other hybrid dynamical cyclic tasks such as walking and running.Johns Hopkins University, Office of the Provos
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Retrograde thoracic spinal cord stimulation paddle placement for complex persistent spinal pain syndrome type 2
No full textBACKGROUNDSpinal cord stimulation (SCS) is a cost-effective option for treating refractory persistent spinal pain syndrome type-2 (PSPS-2). For patients with extensive spine instrumentation including the thoraco-lumbar junction, percutaneous placement of SCS leads is usually not an option being paddle leads typically implanted anterograde. Paddle lead placement will be particularly challenging in more complex cases when the instrumentation covers the targeted level. To overcome this barrier, we studied using a retrograde approach to reach the sweet spot, facilitate the placement, and reduce associated risks.OBJECTIVESTo study the use of retrograde SCS paddle as a placement method to optimize the spinal cord target and reduce the risks of conventional placement in complex cases.STUDY DESIGNCase series and technical note.METHODSWe present three cases of thoracic retrograde SCS paddle lead placement cases, detailing patient selection, operative technique, and outcome. All the cases had extensive instrumentation to the thoraco-lumbar spine, and one had additional spinal canal stenosis. The surgical procedure entailed a retrograde midthoracic inter-laminar approach, flavectomy, and caudal placement of the paddle lead with intraoperative neurophysiologic monitoring (IONM) guidance for functional midline determination.RESULTSAll the cases had a successful lead placement over the sweet spot without complications. The same approach was used to decompress a focal spinal stenosis in one case. One case had significantly improved pain and hence underwent a pulse generator implant. The other cases had non-satisfactory pain control and were explanted.LIMITATIONSThese case description could guide technical procedural steps, however, a larger number of such cases would be needed to describe further technical nuances.CONCLUSIONSWe demonstrated that placing SCS paddle leads via retrograde midthoracic approach with IONM guidance is safe. This procedure should be an option for SCS paddle implants in patients with posterior spinal fusion encompassing the intended targeted spinal stimulation level
Defibrillation safety
No full textIn the past years, there has been a dramatic transition between the use of older monophasic defibrillators to newer, more sophisticated, biphasic types. As these biphasic defibrillators are more efficient, they require less energy and therefore create less of a risk to bystanders. Due to the lack of research around these new defibrillators, the current recommended procedures may not accurately reflect the safety of medical personnel. Because of this, the recommended “all clear” period may in fact become detrimental to the health of the patient as it causes the cessation of crucial activities of medical staff such as IV canalization and chest compressions. This thesis is aimed at assisting in a study to be performed by the Professor of Emergency Medicine at Royal Perth Hospital by designing a device capable of measuring, storing and analyzing the leakage voltages from a patient and their environment whilst undergoing defibrillation.
The device that was designed consisted of a data acquisition system that would measure the voltages using standard ECG leads, and then wirelessly transmit that data to a laptop for further processing. Throughout the entire design process, the focus was aimed at ensuring the device would meet all the criteria specified in the required standards and cause no detrimental effect to the patient being monitored. At the end of the thesis period, a functional schematic was designed and tested, ready for manufacture as well as a solid framework of the software component of the project
Pottery-making in Ban Mai, Muang District, Surin Province, Northeast Thailand and the paddle and anvil technique in Southeast Asia.
No full textThe making of pottery vessels for boiling cocons is extensively carried out in Ban Mai, Muang District, Surin Province, Northeast Thailand. The author investigated the characteristics and manufacturing of those vessels in August 1984. This article reports those findings and also the classification of those examples in Southeast Asia.
Pottery-making at Ban Mai goes through following manufacturing processes.① Gathering clay suitable for pottery.② Kneading and tempering the clay with sand of laterite.③ First stage of forming. Clay is formed into cylinder.④ Second stage of forming. The upper part of pot is formed using the paddle and
anvil. The rim is finished by a piece of cloth.⑤ First stage of Drying.⑥ Third stage of forming. The lower part and the base of pot is formed using the paddle and anvil.⑦ Second stage of drying.⑧ Baking.The pottery-making at Ban Mai is characterized by the forming of the clay into a cylinder by hand and the paddle and anvil technique. The pottery manufacture in
Southeast Asia commonly uses the paddle and anvil technique. Three different methods are seen at the first stage of forming, by potter's wheel, by turn table, and by hand only. And the method of forming by hand is classified into two methods, first, only by hand, second, by buiding a clay belt into a pot. We can see some stages of the technical development in the pottery-making of Southeast Asia. The pottery manufactured at Ban Mai is one of the most primitive in Southeast Asia
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