Design and development of a motion compensator for the RSRA main rotor control

The RSRA, an experimental helicopter, is equipped with an active isolation system that allows the transmission to move relative to the fuselage. The purpose of the motion compensator is to prevent these motions from introducing unwanted signals to the main rotor control. A motion compensator concept was developed that has six-degree-of-freedom capability. The mechanism was implemented on RSRA and its performance verified by ground and flight tests

Compensating linkage for main rotor control

A compensating linkage for the rotor control system on rotary wing aircraft is described. The main rotor and transmission are isolated from the airframe structure by clastic suspension. The compensating linkage prevents unwanted signal inputs to the rotor control system caused by relative motion of the airframe structure and the main rotor and transmission

Airframe-integrated propulsion system for hypersonic cruise vehicles

Research on a new, hydrogen burning, airbreathing engine concept which offers good potential for efficient hypersonic cruise vehicles is considered. Features of the engine which lead to good performance include; extensive engine-airframe integration, fixed geometry, low cooling, and the control of heat release in the supersonic combustor by mixed-modes of fuel injection from the combustor entrance. The engine concept is described along with results from inlet tests, direct-connect combustor tests, and tests of two subscale boiler-plate research engines presently underway at conditions which simulate flight at Mach 4 and 7

Tactile information improves visual object discrimination in kea, Nestor notabilis, and capuchin monkeys, Sapajus spp.

In comparative visual cognition research, the influence of information acquired by nonvisual senses has received little attention. Systematic studies focusing on how the integration of information from sight and touch can affect animal perception are sparse. Here, we investigated whether tactile input improves visual discrimination ability of a bird, the kea, and capuchin monkeys, two species with acute vision, and known for their tendency to handle objects. To this end, we assessed whether, at the attainment of a criterion, accuracy and/or learning speed in the visual modality were enhanced by haptic (i.e. active tactile) exploration of an object. Subjects were trained to select the positive stimulus between two cylinders of the same shape and size, but with different surface structures. In the Sight condition, one pair of cylinders was inserted into transparent Plexiglas tubes. This prevented animals from haptically perceiving the objects' surfaces. In the Sight and Touch condition, one pair of cylinders was not inserted into transparent Plexiglas tubes. This allowed the subjects to perceive the objects' surfaces both visually and haptically. We found that both kea and capuchins (1) showed comparable levels of accuracy at the attainment of the learning criterion in both conditions, but (2) required fewer trials to achieve the criterion in the Sight and Touch condition. Moreover, this study showed that both kea and capuchins can integrate information acquired by the visual and tactile modalities. To our knowledge, this represents the first evidence of visuotactile integration in a bird species. Overall, our findings demonstrate that the acquisition of tactile information while manipulating objects facilitates visual discrimination of objects in two phylogenetically distant species

Single spin probe of Many-Body Localization

We use an external spin as a dynamical probe of many body localization. The probe spin is coupled to an interacting and disordered environment described by a Heisenberg spin chain in a random field. The spin-chain environment can be tuned between a thermalizing delocalized phase and non-thermalizing localized phase, both in its ground- and high-energy states. We study the decoherence of the probe spin when it couples to the environment prepared in three states: the ground state, the infinite temperature state and a high energy N\'eel state. In the non-thermalizing many body localized regime, the coherence shows scaling behaviour in the disorder strength. The long-time dynamics of the probe spin shows a logarithmic dephasing in analogy with the logarithmic growth of entanglement entropy for a bi-partition of a many-body localized system. In summary, we show that decoherence of the probe spin provides clear signatures of many-body localization.Comment: 5 pages, 4 figure

Optimization of a neutrino factory oscillation experiment

We discuss the optimization of a neutrino factory experiment for neutrino oscillation physics in terms of muon energy, baselines, and oscillation channels (gold, silver, platinum). In addition, we study the impact and requirements for detector technology improvements, and we compare the results to beta beams. We find that the optimized neutrino factory has two baselines, one at about 3000 to 5000km, the other at about 7500km (``magic'' baseline). The threshold and energy resolution of the golden channel detector have the most promising optimization potential. This, in turn, could be used to lower the muon energy from about 50GeV to about 20GeV. Furthermore, the inclusion of electron neutrino appearance with charge identification (platinum channel) could help for large values of \sin^2 2 \theta_{13}. Though tau neutrino appearance with charge identification (silver channel) helps, in principle, to resolve degeneracies for intermediate \sin^2 2 \theta_{13}, we find that alternative strategies may be more feasible in this parameter range. As far as matter density uncertainties are concerned, we demonstrate that their impact can be reduced by the combination of different baselines and channels. Finally, in comparison to beta beams and other alternative technologies, we clearly can establish a superior performance for a neutrino factory in the case \sin^2 2 \theta_{13} < 0.01.Comment: 51 pages, 25 figures, 6 tables, references corrected, final version to appear in Phys. Rev.

A CASE STUDY ON BALANCE RECOVERY IN SLACKLINING

The purpose of this study was to identify and describe the basic balance recovery movements performed during slackline balancing. Slacklining is an activity where the athlete balances on a thin piece of webbing that is mounted between two fixed points in a not too tight way. We designed an experimental setting where a controlled perturbation is applied to the slackline and study the movements of athletes to regain a balanced position. Four athletes took part in the study and for each we recorded five trials using a Vicon motion capture system. With the help of a 15 segment biomechanical model we studied mechanical quantities like the center of mass trajectory, the energy contributions, and also analyzed joint actuation patterns

Criteria for self-ignition of supersonic hydrogen-air mixtures

A correlation of available self ignition data for supersonic hydrogen-air mixtures in configurations representative of scramjet combustors was made. The correlation was examined in light of simplified ignition-limit models. The data and model included cases of injection from transverse fuel jets on walls, transverse jets behind swept and unswept steps, and transverse injection ahead of swept and unswept steps and strut bases. The results provide useful guidance for predicting self ignition in a variety of applications. The likely regions for self ignition in a combustor are given in order of merit