The timing and magnitude of upper body muscular activity during a field hockey hit

The aim of this study was to investigate the contributions to stick motion in the field hockey hit by monitoring muscle activity in the arms and trunk and synchronising these with arm and stick kinematics. The hits of ten male, university-level field hockey players were analysed. Whilst their interpretation is complicated by the closed kinetic loop formed by the arms and stick, the data collected here represent a step forward in establishing the contributions from muscular activity and segmental interactions to the field hockey hit. This study has shown that EMG analysis alone is not sufficient to explain the nature of muscular activity patterns and that the temporal aspects of EMG need to be examined in combination with kinematic data to ascertain the role of muscular activity during movement

Swashplate feedback control for tilt-rotor aircraft

Changes in angle of attack in system were sensed indirectly by gages which responded to strains induced in wing structure. Output signals were amplified, filtered, and used to activate swashplate actuators. System provided significant reduction in blade loads and desirable changes in hub forces and moments

CARETS: A prototype regional environmental information system. Volume 11: Potential usefulness of CARETS data for environmental impact assessment

There are no author-identified significant results in this report

Wind tunnel test on a 1/4.622 Froude scale, hingeless rotor, tilt rotor model, volume 1

Wing tunnel test data on a 1/4.622 Froude scale, hingeless rotor, tilt rotor mode are reported for all potential flight conditions through hover and a wide envelope of transitions. A mathematical model was used to describe the rotor system in real time simulation by means of regression analyses. Details of the model, test program and data system are provided together with four data files for hover and transition

Long-Term Risks and Short-Term Regulations: Modeling the Transition from Enhanced Oil Recovery to Geologic Carbon Sequestration

Recent policy debates suggest that geologic carbon sequestration (GS) likely will play an important role in a carbon-constrained future. As GS evolves from the analogous technologies and practices of enhanced oil recovery (EOR) operations to a long-term, dedicated emissions mitigation option, regulations must evolve simultaneously to manage the risks associated with underground migration and surface tresspass of carbon dioxide (CO2). In this paper, we develop a basic engineering-economic model of four illustrative strategies available to a sophisticated site operator to better understand key deployment pathways in the transition from EOR to GS operations. All of these strategies focus on whether or not a sophisticated site operator would store CO2 in a geologic formation. We evaluate these strategies based on illustrative scenarios of (a) oil and CO2 prices; (b) leakage estimates; and (c) transportation, injection, and monitoring costs, as obtained from our understanding of the literature. Major results reveal that CO2 storage in depleted hydrocarbon reservoirs after oil recovery is associated with the greatest net revenues (i.e., the “most-preferred” strategy) under a range of scenarios. This finding ultimately suggests that GS regulatory design should anticipate the use of the potentially leakiest, or “worst,” sites first.carbon sequestration, enhanced oil recovery, leakage, regulatory design, risk management

Reversible signal transmission in an active mechanical metamaterial

Mechanical metamaterials are designed to enable unique functionalities, but are typically limited by an initial energy state and require an independent energy input to function repeatedly. Our study introduces a theoretical active mechanical metamaterial that incorporates a biological reaction mechanism to overcome this key limitation of passive metamaterials. Our material allows for reversible mechanical signal transmission, where energy is reintroduced by the biologically motivated reaction mechanism. By analysing a coarse grained continuous analogue of the discrete model, we find that signals can be propagated through the material by a travelling wave. Analysis of the continuum model provides the region of the parameter space that allows signal transmission, and reveals similarities with the well-known FitzHugh-Nagumo system. We also find explicit formulae that approximate the effect of the timescale of the reaction mechanism on the signal transmission speed, which is essential for controlling the material.Comment: 20 pages, 7 figure