1,138 research outputs found
Fixed-base simulation evaluation of various low-visibility landing systems for helicopters
Fixed base simulation evaluation of one fully automatic and six manual low visibility landing systems for helicopter
Aircraft control system
An aircraft control system is described which is particularly suited to rotary wing aircraft. Longitudinal acceleration and course rate commands are derived from a manual control stick to control translational velocity of the aircraft along a flight path. In the collective channel the manual controls provide vertical velocity commands. In the yaw channel the manual controls provide sideslip or heading rate commands at high or low airspeeds, respectively. The control system permits pilots to fly along prescribed flight paths in a precise manner with relatively low work load
Intrinsic Pinning in the High Field C-Phase of UPt_3
We report on the a.c. magnetic response of superconducting UPt_3 in a d.c.
magnetic field. At low fields (H < H^*), the in-phase susceptibility shows a
sharp drop at followed by a gradual decrease with decreasing temperature,
while the out-of-phase component shows a large peak at T_c followed by an
unusual broad peak. As the B-C phase line is crossed (H>H^*), however, both the
in-phase and out-of-phase susceptibilities resemble the zero-field Meissner
curves. We interpret these results in terms of a vortex pinning force which,
while comparatively small in the A/B-phases, becomes large enough to
effectively prevent vortex motion in the C-phase.Comment: Modified discussion, slight changes to figures, accepted in PRB Rapid
Communications. RevTex file, 5 figure
Non-genomic Effects of Glucocorticoids: An Updated View
Glucocorticoid (GC) anti-inflammatory effects generally require a prolonged onset of action and involve genomic processes. Because of the rapidity of some of the GC effects, however, the concept that non-genomic actions may contribute to GC mechanisms of action has arisen. While the mechanisms have not been completely elucidated, the non-genomic effects may play a role in the management of inflammatory diseases. For instance, we recently reported that GCs ‘rapidly’ enhanced the effects of bronchodilators, agents used in the treatment of allergic asthma. In this review article, we discuss (i) the non-genomic effects of GCs on pathways relevant to the pathogenesis of inflammatory diseases and (ii) the putative role of the membrane GC receptor. Since GC side effects are often considered to be generated through its genomic actions, understanding GC non-genomic effects will help design GCs with a better therapeutic index
Extreme magneto-transport of bulk carbon nanotubes in sorted electronic concentrations and aligned high performance fiber
We explored high-field (60T) magneto-resistance (MR) with two carbon nanotube (CNT) material classes: (1) unaligned single-wall CNTs (SWCNT) films with controlled metallic SWCNT concentrations and doping degree and (2) CNT fiber with aligned, long-length microstructure. All unaligned SWCNT films showed localized hopping transport where high-field MR saturation definitively supports spin polarization instead of a more prevalent wave function shrinking mechanism. Nitric acid exposure induced an insulator to metal transition and reduced the positive MR component. Aligned CNT fiber, already on the metal side of the insulator to metal transition, had positive MR without saturation and was assigned to classical MR involving electronic mobility. Subtracting high-field fits from the aligned fiber's MR yielded an unconfounded negative MR, which was assigned to weak localization. It is concluded that fluctuation induced tunnelling, an extrinsic transport model accounting for most of the aligned fiber's room temperature resistance, appears to lack MR field dependence
Intrinsic Properties of AFe2As2 (A = Ba, Sr) Single Crystal under Highly Hydrostatic Pressure Conditions
We measured the electrical resistivity and ac magnetic susceptibility of
BaFe2As2 and SrFe2As2 single crystals under pressure using a cubic anvil
apparatus. For BaFe2As2, the antiferromagnetic (AF) and structural transitions
are suppressed with increasing pressure. Unexpectedly, these transitions
persist up to 8 GPa, and no signature of a superconducting transition was
observed in the pressure range investigated here. On the other hand, the AF and
structural transitions of SrFe2As2 collapse at around the critical pressure Pc
~ 5 GPa, resulting in the appearance of bulk superconductivity. The
superconducting volume fraction abruptly increases above Pc, and shows a dome
centered at approximately 6 GPa. Our results suggest that the bulk
superconducting phase competes with the AF/orthorhombic phase and only appears
in the narrow pressure region of the tetragonal phase.Comment: 4 pages, 4 figures; accepted for publication in J. Phys. Soc. Jp
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