Aircraft nose wheel steering : a gyroscopic precession study

During flight test of the AV8B nose wheel steering system, gyroscopic precession was inadvertently encountered. Following a touch and go landing with a 180 degree turn to downwind, the spinning nose wheel caused the nose landing gear strut to process away from a centered conditioned. The physical properties of nose wheel\u27s angular momentum coupled with the pilot\u27s technique can easily be seen to have caused the precession however, this phenomenon had never been seen during the previous 13 years of the Harrier\u27s existence. Toquantify this behavior, a study of gyroscopic precession as it applies to aircraft landing gear is presented. Understanding how the aircraft nose landing system works in conjunction with the operational procedures employed is critical to understanding why this precession had not previously been detected in other aircraft either. Accordingly, a discussion is presented. Following that, a data presentation section describes the test aircraft and limitations to data collection during the flight test events. A mathematical.model was also developed to show how the flight test results conformed to gyroscopic theory.Analysis of the test data and the mathematical model provided insights about gyroscopic precession in the AV8B nose landing gear system. The data indicated that gyroscopic precession of the nose strut was a function of several variables. Contributing factors were the nose wheel rotational velocity, the aircraft roll rate, and the aircraft roll acceleration. The gyroscopic precession appeared to be mostly due to high rotational wheel speed velocity at the point of aircraft maneuver however, it was discovered that there was a large dependency on aircraft initial roll rate and roll acceleration. The data also revealed that although precession trends can be predicted, an absolute solution is quite unpredictable. The single most important factor during this study of nose wheel gyroscopic precession was pilot technique since this defined the aircraft roll rate,roll acceleration, and nose wheel rotational velocity that generated the precessional moment on the nose strut. It is highly recommended that landing gear design engineers find a method to inhibit nose landing gear strut precession thereby ensuring that pilots do not have to contend with this dangerous phenomenon

EAPC task force on education for psychologists in palliative care

It is argued that psychological aspects of care and psychosocial problems are essential components of palliative care. However, the provision of appropriate services remains somewhat arbitrary. Unlike medical and nursing care, which are clearly delivered by doctors and nurses respectively, psychological and psychosocial support in palliative care are not assigned exclusively to psychologists. It is generally expected that all professionals working in palliative care should have some knowledge of the psychological dynamics in terminal illness, as well as skills in communication and psychological risk assessment. On the one hand, palliative care education programmes for nurses and doctors comprise a considerable amount of psychological and psychosocial content. On the other hand, only a few palliative care associations provide explicit information on the role and tasks of psychologists in palliative care. Psychologists’ associations do not deal much with this issue either. If they refer to it at all, it is in the context of the care of the aged, end-of-life care or how to deal with grief

Develop and test fuel cell powered on-site integrated total energy system

Test results are presented for a 24 cell, two sq ft (4kW) stack. This stack is a precursor to a 25kW stack that is a key milestone. Results are discussed in terms of cell performance, electrolyte management, thermal management, and reactant gas manifolding. The results obtained in preliminary testing of a 50kW methanol processing subsystem are discussed. Subcontracting activities involving application analysis for fuel cell on site integrated energy systems are updated

Develop and test fuel cell powered on-site integrated total energy systems: Phase 3, full-scale power plant development

A 25 cell stack of the 13 inch x 23 inch cell size (about 4kW) remains on test after 6000 hours, using simulated reformate fuel. A similar stack was previously shut down after 7000 hours on load. These tests were carried out for the purpose of assessing the durability of fuel cell stack components developed through the end of 1983. In light of the favorable results obtained, a 25kW stack that will contain 175 cells of the same size is being constructed using the same technology base. The components for the 25kW stack have been completed. A methanol steam reformer with a design output equivalent to 50kW has been constructed to serve as a hydrogen generator for the 25kW stack. This reformer and the balance of the fuel processing sub system are currently being tested and debugged. The stack technology development program focused on cost reduction in bipolar plates, nonmetallic cooling plates, and current collecting plates; more stable cathode catalyst support materials; more corrosion resistant metal hardware; and shutdown/start up tolerance

The phase diagram of neutral quark matter: The effect of neutrino trapping

We study the effect of neutrino trapping on the phase diagram of dense, locally neutral three-flavor quark matter within the framework of a Nambu--Jona-Lasinio model. In the analysis, dynamically generated quark masses are taken into account self-consistently. The phase diagrams in the plane of temperature and quark chemical potential, as well as in the plane of temperature and lepton-number chemical potential are presented. We show that neutrino trapping favors two-flavor color superconductivity and disfavors the color-flavor-locked phase at intermediate densities of matter. At the same time, the location of the critical line separating the two-flavor color-superconducting phase and the normal phase of quark matter is little affected by the presence of neutrinos. The implications of these results for the evolution of protoneutron stars are briefly discussed.Comment: 10 pages, 9 figures, references added; version accepted for publication in Phys. Rev.

The phase diagram of neutral quark matter : self-consistent treatment of quark masses

We study the phase diagram of dense, locally neutral three-flavor quark matter within the framework of the Nambu--Jona-Lasinio model. In the analysis, dynamically generated quark masses are taken into account self-consistently. The phase diagram in the plane of temperature and quark chemical potential is presented. The results for two qualitatively different regimes, intermediate and strong diquark coupling strength, are presented. It is shown that the role of gapless phases diminishes with increasing diquark coupling strength

Develop and test fuel cell powered on-site integrated total energy systems

On-going testing of an 11 cell, 10.7 in. x 14 in. stack (about 1 kW) reached 2600 hours on steady load. Nonmetallic cooling plates and an automated electrolyte replenishment system continued to perform well. A 10 cell, 10.7 in. x 14 in. stack was constructed with a modified electrolyte matrix configuration for the purpose of reducing cell IR loss. The desired effect was achieved, but the general cell performance level was irregular. Evaluation is continuing. Preparations for a long term 25 cell, 13 in. x 23 in. test stack (about 4 kW) approached completion. Start up in early May 1984 is expected

Phase diagram of neutral quark matter at moderate densities

We discuss the phase diagram of moderately dense, locally neutral three-flavor quark matter using the framework of an effective model of quantum chromodynamics with a local interaction. The phase diagrams in the plane of temperature and quark chemical potential as well as in the plane of temperature and lepton-number chemical potential are discussed.Comment: 32 pages, 11 figures; contribution to the proceedings of the INT workshop "Pairing in fermionic systems", Seattle, September 19-23, 200