7,715 research outputs found
Lander, R M (Raymond Malcolm), WX11228
No full textThis record was harvested from a previous catalogue system and will be withdrawn in 2025. Information in this record may be superseded or incomplete. Visit this record in UMA's new catalogue at: https://archives.library.unimelb.edu.au/nodes/view/398180Surname: LANDER. Given Name(s) or Initials: R M (RAYMOND MALCOLM). Military Service Number or Last Known Location: WX11228. Missing, Wounded and Prisoner of War Enquiry Card Index Number: 16357.237192
Item: [2016.0049.30473] "Lander, R M (Raymond Malcolm), WX11228
The inside-out view on neutron-star magnetospheres
No full textWe construct hydromagnetic neutron star equilibria which allow for a non-zero electric current distribution in the exterior. The novelty of our models is that the neutron star's interior field is in equilibrium with its magnetosphere, thus bridging the gap between previous work in this area, which either solves for the interior assuming a vacuum exterior or solves for the magnetosphere without modelling the star itself. We consider only non-rotating stars in this work, so our solutions are most immediately applicable to slowly rotating systems such as magnetars. Nonetheless, we demonstrate that magnetospheres qualitatively resembling those expected for both magnetars and pulsars are possible within our framework. The ‘inside-out’ approach taken in this paper should be more generally applicable to rotating neutron stars, where the interior and exterior regions are again not independent but evolve together
J. R. Lander, Crown and nobility, 1450-1509
No full textGenet Jean-Philippe. J. R. Lander, Crown and nobility, 1450-1509. In: Annales. Économies, Sociétés, Civilisations. 35ᵉ année, N. 5, 1980. pp. 1072-1074
J. R. Lander, Government and Community, England 1450-1509
No full textGenet Jean-Philippe. J. R. Lander, Government and Community, England 1450-1509. In: Annales. Économies, Sociétés, Civilisations. 38ᵉ année, N. 1, 1983. p. 198
Mars pathfinder lander deployment mechanisms
No full textThe Mars Pathfinder Lander employs numerous mechanisms, as well as autonomous mechanical functions, during its Entry, Descent and Landing (EDL) Sequence. This is the first US lander of its kind, since it is unguided and airbag-protected for hard landing using airbags, instead of retro rockets, to soft land. The arrival condition, location, and orientation of the Lander will only be known by the computer on the Lander. The Lander will then autonomously perform the appropriate sequence to retract the airbags, right itself, and open, such that the Lander is nearly level with no airbag material covering the solar cells. This function uses two different types of mechanisms - the Airbag Retraction Actuators and the Lander Petal Actuators - which are designed for the high torque, low temperature, dirty environment and for limited life application. The development of these actuators involved investigating low temperature lubrication, Electrical Discharge Machining (EDM) to cut gears, and gear design for limited life use
Mars lander survey
No full textThe requirements, issues, and design options are reviewed for manned Mars landers. Issues such as high 1/d versus low 1/d shape, parking orbit, and use of a small Mars orbit transfer vehicle to move the lander from orbit to orbit are addressed. Plots of lander mass as a function of Isp, destination orbit, and cargo up and down, plots of initial stack mass in low Earth orbit as a function of lander mass and parking orbit, detailed weight statements, and delta V tables for a variety of options are included. Lander options include a range from minimum landers up to a single stage reusable design. Mission options include conjunction and Venus flyby trajectories using all-cryogenic, hybrid, NERVA, and Mars orbit aerobraking propulsion concepts
Equilibria and oscillations of magnetised neutron stars
No full textWe investigate equilibrium configurations and oscillation spectra of neutron stars,modelled as rotating magnetised fluid bodies in Newtonian gravity. We also explorethe idea that these model neutron stars could have dynamics analogous to rigid-bodyfree precession.In axisymmetry, the equations of magnetohydrodynamics reduce to a purelytoroidal-field case and a mixed-field case (with a purely poloidal-field limit). Wesolve these equations using a nonlinear code which finds stationary rotating magnetisedstars by an iterative procedure. We find that despite the general nature ofour approach, the mixed-field configurations we produce are all dominated by theirpoloidal component. We calculate distortions induced both by magnetic fields andby rotation; our results suggest that the relationship between the magnetic energyand the induced ellipticity should be close to linear for all known neutron stars.We then investigate the oscillation spectra of neutron stars, using these stationaryconfigurations as a background on which to study perturbations. This is doneby evolving the perturbations numerically, making the Cowling approximation andspecialising to purely toroidal fields for simplicity. The results of the evolutionsshow a number of magnetically-restored Alfv´en modes. We find that in a rotatingstar pure inertial and pure Alfv´en modes are replaced by hybrid magneto-inertialmodes. We also show that magnetic fields appear to reduce the effect of the r-modeinstability.Finally, we look at precession-like dynamics in magnetised fluid stars, using bothanalytic and numerical methods. Whilst these studies are only preliminary, theyindicate deficiencies in previous research on this topic. We suggest ways in whichthe problem of magnetised-fluid precession could be better understood
Multibody simulation and descent control of a space lander
No full textThis paper analyzes the terminal descent phase of a space lander on a surface of a celestial body. A multibody approach is adopted to build the physical model of the lander and the surface. In this work, a legged landing gear system is considered. Opportune modelling of the landing gear crashbox is implemented in order to accurately predict the kinetic energy. To ensure the stability of the lander while impacting the ground and to reduce the contact forces that arise in this maneuver, the multibody model makes use of a co-simulation with a dedicated control system. Two types of control systems are considered; one with only position variables and the other with position and velocity variables. The results demonstrate the good reliability of modern multibody technology to incorporate control algorithms to carry out stability analysis of ground impact of space landers. Moreover, from a comparison between the two control systems adopted, it is shown how the velocity control leads to lower contact forces and fuel consumption
Magnetic fields in axisymmetric neutron stars
No full textWe derive general equations for axisymmetric Newtonian magnetohydrodynamics and use these as the basis of a code for calculating equilibrium configurations of rotating magnetized neutron stars in a stationary state. We investigate the field configurations that result from our formalism, which include purely poloidal, purely toroidal and mixed fields. For the mixed-field formalism, the toroidal component appears to be bounded at less than 7 per cent. We calculate distortions induced both by magnetic fields and by rotation. From our non-linear work, we are able to look at the realm of validity of perturbative work: we find for our results that perturbative-regime formulae for magnetic distortions agree to within 10 per cent of the non-linear results if the ellipticity is less than 0.15 or the average field strength is less than 10^17 G. We also consider how magnetized equilibrium structures vary for different polytropic indices
Viking lander spacecraft battery
No full textThe Viking Lander was the first spacecraft to fly a sterilized nickel-cadmium battery on a mission to explore the surface of a planet. The significant results of the battery development program from its inception through the design, manufacture, and test of the flight batteries which were flown on the two Lander spacecraft are documented. The flight performance during the early phase of the mission is also presented
- …
