The Experts below are selected from a list of 18873 Experts worldwide ranked by ideXlab platform
Yu Zhou - One of the best experts on this subject based on the ideXlab platform.
-
design and characterization of an electromagnetic energy harvester for vehicle suspensions
Smart Materials and Structures, 2010Co-Authors: Brian Scully, Jurgen Shestani, Yu ZhouAbstract:During the everyday usage of an automobile, only 10–16% of the fuel energy is used to drive the car—to overcome the resistance from road friction and Air Drag. One important loss is the dissipation of vibration energy by shock absorbers in the vehicle suspension under the excitation of road irregularity and vehicle acceleration or deceleration. In this paper we design, characterize and test a retrofit regenerative shock absorber which can efficiently recover the vibration energy in a compact space. Rare-earth permanent magnets and high permeable magnetic loops are used to configure a four-phase linear generator with increased efficiency and reduced weight. The finite element method is used to analyze the magnetic field and guide the design optimization. A theoretical model is created to analytically characterize the waveforms and regenerated power of the harvester at various vibration amplitudes, frequencies, equilibrium positions and design parameters. It was found that the waveform and RMS voltage of the individual coils will depend on the equilibrium position but the total energy will not. Experimental studies of a 1:2 scale prototype are conducted and the results agree very well with the theoretical predictions. Such a regenerative shock absorber will be able to harvest 16–64 W power at 0.25–0.5 m s − 1 RMS suspension velocity.
-
design and characterization of an electromagnetic energy harvester for vehicle suspensions
ASME 2009 International Mechanical Engineering Congress and Exposition, 2009Co-Authors: Brian Scully, Jurgen Shestani, Yu ZhouAbstract:During the everyday usage of an automobile, only 10–16% of the fuel energy is used to drive the car — to overcome the resistance from road friction and Air Drag. One important loss is the dissipation of vibration energy by shock absorbers in the vehicle suspension under the excitation of road irregularity and vehicle acceleration or deceleration. In this paper we design, characterize, and test a retrofit regenerative shock absorber which can efficiently recover the vibration energy in a compact space. Rare-earth permanent magnets and high permeable magnetic loop are used to configure a four-phase linear generator with increased efficiency and reduced weight. Finite element method is used to analyze the magnetic field and guide the design optimization. A theoretical model is created to analyze the waveforms and regenerated energy of the harvester at various vibration amplitudes, frequencies, equilibrium positions, and design parameters. Experimental studies of a 1:2-scale prototype are conducted and the results agree very well with the theoretical predictions.Copyright © 2009 by ASME
Roald Bahr - One of the best experts on this subject based on the ideXlab platform.
-
injury prevention advances in alpine ski racing harnessing collaboration with the international ski federation fis long term surveillance and digital technology to benefit athletes
British Journal of Sports Medicine, 2014Co-Authors: Tone Bere, Roald BahrAbstract:Everything that can be counted does not necessarily count; everything that counts cannot necessarily be counted (Albert Einstein 1879-1955). Alpine ski racing is an Olympic winter sport where athletes ski one by one down the mountain on a demanding course, often in challenging snow and weather conditions. The Athletes must ski as efficiently as possible, as performance is determined by the racing time measured to 0.01 s, but at the same time they have to adapt speed and trajectory to their technical skills and manage risk responsibly. In this issue, Gilgien et al 1 quantify and describe the mechanical characteristics (such as skier speed, turn radius, Air Drag force, ground reaction force, jump distance and Airtime) of World Cup alpine skiing under real race conditions, and interestingly they link these data to the risk of injury. With their biomechanical approach, they add new and valuable information to the field of injury prevention …
Brian Scully - One of the best experts on this subject based on the ideXlab platform.
-
design and characterization of an electromagnetic energy harvester for vehicle suspensions
Smart Materials and Structures, 2010Co-Authors: Brian Scully, Jurgen Shestani, Yu ZhouAbstract:During the everyday usage of an automobile, only 10–16% of the fuel energy is used to drive the car—to overcome the resistance from road friction and Air Drag. One important loss is the dissipation of vibration energy by shock absorbers in the vehicle suspension under the excitation of road irregularity and vehicle acceleration or deceleration. In this paper we design, characterize and test a retrofit regenerative shock absorber which can efficiently recover the vibration energy in a compact space. Rare-earth permanent magnets and high permeable magnetic loops are used to configure a four-phase linear generator with increased efficiency and reduced weight. The finite element method is used to analyze the magnetic field and guide the design optimization. A theoretical model is created to analytically characterize the waveforms and regenerated power of the harvester at various vibration amplitudes, frequencies, equilibrium positions and design parameters. It was found that the waveform and RMS voltage of the individual coils will depend on the equilibrium position but the total energy will not. Experimental studies of a 1:2 scale prototype are conducted and the results agree very well with the theoretical predictions. Such a regenerative shock absorber will be able to harvest 16–64 W power at 0.25–0.5 m s − 1 RMS suspension velocity.
-
design and characterization of an electromagnetic energy harvester for vehicle suspensions
ASME 2009 International Mechanical Engineering Congress and Exposition, 2009Co-Authors: Brian Scully, Jurgen Shestani, Yu ZhouAbstract:During the everyday usage of an automobile, only 10–16% of the fuel energy is used to drive the car — to overcome the resistance from road friction and Air Drag. One important loss is the dissipation of vibration energy by shock absorbers in the vehicle suspension under the excitation of road irregularity and vehicle acceleration or deceleration. In this paper we design, characterize, and test a retrofit regenerative shock absorber which can efficiently recover the vibration energy in a compact space. Rare-earth permanent magnets and high permeable magnetic loop are used to configure a four-phase linear generator with increased efficiency and reduced weight. Finite element method is used to analyze the magnetic field and guide the design optimization. A theoretical model is created to analyze the waveforms and regenerated energy of the harvester at various vibration amplitudes, frequencies, equilibrium positions, and design parameters. Experimental studies of a 1:2-scale prototype are conducted and the results agree very well with the theoretical predictions.Copyright © 2009 by ASME
Daniel Attinger - One of the best experts on this subject based on the ideXlab platform.
-
implications of two backward blood spatter models based on fluid dynamics for bloodstain pattern analysis
Forensic Science International, 2019Co-Authors: P M Comiskey, Alexander L. Yarin, Daniel AttingerAbstract:Abstract Bloodstain pattern analysis (BPA) is an integral part of crime scene investigation. For violent crimes involving gunshots, standard practice in police departments worldwide have some physical limitations. For instance, the effect of gravity and Air Drag on trajectories of blood droplets are neglected using current reconstruction methods, which results in a well-known overestimation of the height of the source of blood. As a consequence, more sophisticated models for blood spatter trajectory reconstruction are being developed, two of which are highlighted in the present work. They allow the prediction of bloodstain patterns produced from backward spattered blood droplets from blunt and sharp bullets. Our recent models attribute the splashing of blood to the Rayleigh–Taylor instability which arises when blood is accelerated towards lighter Air. This physically-based description comes with the powerful predictive capability to correlate features of bloodstain patterns with the specific bullet and gun that produced them, as well as with the body position. The results of the numerical models were compared with four experiments simulating blood spatter deposition on a vertical wall through the number of stains produced, average stain area, and average impact angle at the surface, and the agreement found is fAirly good. Moreover, further insight is obtained by probing and explaining the influence of observable parameters on the resulting spatter pattern, with the goal of aiding BPA experts evaluating a crime scene.
Ian Hewitt - One of the best experts on this subject based on the ideXlab platform.
-
rolling resistance of shallow granular deformation
Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 2017Co-Authors: Keaton J Burns, N J Balmforth, Ian HewittAbstract:Experiments are conducted to measure the resistance experienced by light cylinders rolling over flat beds of granular media. Sand and glass spheres are used for the beds. The trajectories of the rolling cylinders are determined through optical tracking, and velocity and acceleration data are inferred through fits to these trajectories. The rolling resistance is dominated by a velocity-independent component, but a velocity-dependent Drag exceeding the expected strength of Air Drag is also observed. The results are compared to a theoretical model based on a cohesionless Mohr–Coulomb rheology for a granular medium in the presence of gravity. The model idealizes the flow pattern underneath the rolling cylinder as a plastically deforming zone in front of a rigidly rotating plug attached to the cylinder, as proposed previously for cylinders rolling on perfectly cohesive plastic media. The leading-order, rate-independent rolling resistance observed experimentally is well reproduced by the model predictions.