Localization accuracy of multiple magnets in a myokinetic control interface

Magnetic localizers have been widely investigated in the biomedical field, especially for intra-body applications, because they don’t require a free line-of-sight between the implanted magnets and the magnetic field sensors. However, while researchers have focused on narrow and specific aspects of the localization problem, no one has comprehensively searched for general design rules for accurately localizing multiple magnetic objectives. In this study, we sought to systematically analyse the effects of remanent magnetization, number of sensors, and geometrical configuration (i.e. distance among magnets—Linter-MM—and between magnets and sensors—LMM-sensor) on the accuracy of the localizer in order to unveil the basic principles of the localization problem. Specifically, through simulations validated with a physical system, we observed that the accuracy of the localization was mainly affected by a specific angle ($$\theta$$ θ = tan−1(Linter-MM / LMM-sensor)), descriptive of the system geometry. In particular, while tracking nine magnets, errors below ~ 1 mm (10% of the length of the simulated trajectory) and around 9° were obtained if θ ≥ ~ 31°. The latter proved a general rule across all tested conditions, also when the number of magnets was doubled. Our results are interesting for a whole range of biomedical engineering applications exploiting multiple-magnets tracking, such as human–machine interfaces, capsule endoscopy, ventriculostomy interventions, and endovascular catheter navigation.

Studies and simulations on the flight trajectories of spinning table tennis ball via high-speed camera vision tracking system

When a table tennis ball is hit by a racket, the ball spins and undergoes a complex trajectory in the air. In this article, a model of a spinning ball is proposed for simulating and predicting the ball flight trajectory including the topspin, backspin, rightward spin, leftward spin, and combined spin. The actual trajectory and rotational motion of a flying ball are captured by three high-speed cameras and then reconstructed using a modified vision tracking algorithm. For the purpose of model validation, the simulated trajectory is compared to the reconstructed trajectory, resulting in a deviation of only 2.42%. Such high modeling accuracy makes this proposed method an ideal tool for developing the virtual vision systems emulating the games that can be used to train table tennis players efficiently.

An explicit-solvent conformation search method using open software

Computer modeling is a popular tool to identify the most-probable conformers of a molecule. Although the solvent can have a large effect on the stability of a conformation, many popular conformational search methods are only capable of describing molecules in the gas phase or with an implicit solvent model. We have developed a work-flow for performing a conformation search on explicitly-solvated molecules using open source software. This method uses replica exchange molecular dynamics (REMD) to sample the conformational states of the molecule efficiently. Cluster analysis is used to identify the most probable conformations from the simulated trajectory. This work-flow was tested on drug molecules α-amanitin and cabergoline to illustrate its capabilities and effectiveness. The preferred conformations of these molecules in gas phase, implicit solvent, and explicit solvent are significantly different.

An explicit-solvent conformation search method using open software

Computer modeling is a popular tool to identify the most-probable conformers of a molecule. Although the solvent can have a large effect on the stability of a conformation, many popular conformational search methods are only capable of describing molecules in the gas phase or with an implicit solvent model. We have developed a work-flow for performing a conformation search on explicitly-solvated molecules using open source software. This method uses replica exchange molecular dynamics to sample the conformational states of the molecule efficiently. Cluster analysis is used to identify the most probable conformations from the simulated trajectory. This work-flow was tested on drug molecules a-amanitin and cabergoline to illustrate its capabilities and effectiveness. The preferred conformations of these molecules in gas phase, implicit solvent, and explicit solvent are significantly different.

An explicit-solvent conformation search method using open software

Computer modeling is a popular tool to identify the most-probable conformers of a molecule. Although the solvent can have a large effect on the stability of a conformation, many popular conformational search methods are only capable of describing molecules in the gas phase or with an implicit solvent model. We have developed a work-flow for performing a conformation search on explicitly-solvated molecules using open source software. This method uses replica exchange molecular dynamics to sample the conformational states of the molecule efficiently. Cluster analysis is used to identify the most probable conformations from the simulated trajectory. This work-flow was tested on drug molecules a-amanitin and cabergoline to illustrate its capabilities and effectiveness. The preferred conformations of these molecules in gas phase, implicit solvent, and explicit solvent are significantly different.

Evidence That an Optical Tail in the Gulf of Mexico After Tropical Cyclone Isaac was the Result of Offshore Advection of Coastal Water

This study investigates the hypothesis of Acker's Web report in 2013 that an optical tail of high chlorophyll a, observed in the open Gulf of Mexico (GoM) approximately 2 weeks after tropical storm Isaac made landfall in coastal Louisiana, was due to advection of outflowing Mississippi River related with the mesoscale eddy field in the open GoM. By using available in situ data and data from multiple satellites, strong evidence was found to support Acker's hypothesis. Drifting buoy, remotely sensed sea surface salinity, and surface geostrophic current data were used to show that low-salinity water (LSW) was indeed associated with the optical tail. Remotely sensed colored dissolved organic matter indicated that the LSW was of coastal origin, and satellite-observed rain rate indicated that this LSW in the optical tail was not due to local precipitation. The path of freshwater from the Mississippi River Delta to the region offshore in the optical tail was shown to be similar to a simulated trajectory estimated by surface geostrophic currents; likewise, the drifting buoys deployed near the shelf break offshore of the Mississippi River Delta prior to the peak in discharge.

Ablative Heat Shield Design for Reentry Vehicle Using Numerical Analysis

At this paper, the thermal behavior of ablative materials as heat shields for reentry vehicles is investigated numerically. A one-dimensional finite difference solver is developed to simulate governing mass and energy equations. Four ablative materials; AVCO 5026-HCG, Carbon-Phenolic, Nylon-Phenolic, and Silica-Phenolic; are considered as a heat shield material for a reentry capsule with the diameter 2.8 meter. A heat flux profile from a simulated trajectory of a reentry capsule is used for investigation the performance and essential thickness of these four ablative materials. The only restriction for this simulation is the ultimate temperature of the backup structure which is beneath the ablative heat shield. At all simulations, the final thickness is defined by reaching the interface temperature, the temperature of the border between the ablative heat shield and solid shell, to 80±0.5 degrees Celsius. In addition, the sensitivity analysis is carried out to investigate the effect of properties variations on Carbon-Phenolic’s thickness for this specific heat flux profile.