720 research outputs found
Studies and analyses of the space shuttle main engine: High-pressure oxidizer turbopump failure information propagation model
The high-pressure oxidizer turbopump (HPOTP) failure information propagation model (FIPM) is presented. The text includes a brief discussion of the FIPM methodology and the various elements which comprise a model. Specific details of the HPOTP FIPM are described. Listings of all the HPOTP data records are included as appendices
Ferromagnetic resonance study of sputtered Co|Ni multilayers
We report on room temperature ferromagnetic resonance (FMR) studies of [
Co Ni]N sputtered films, where nm. Two
series of films were investigated: films with same number of CoNi bilayer
repeats (N=12), and samples in which the overall magnetic layer thickness is
kept constant at 3.6 nm (N=1.2/). The FMR measurements were conducted with a
high frequency broadband coplanar waveguide up to 50 GHz using a flip-chip
method. The resonance field and the full width at half maximum were measured as
a function of frequency for the field in-plane and field normal to the plane,
and as a function of angle to the plane for several frequencies. For both sets
of films, we find evidence for the presence of first and second order
anisotropy constants, and . The anisotropy constants are strongly
dependent on the thickness , and to a lesser extent on the total thickness
of the magnetic multilayer. The Land\'e g-factor increases with decreasing
and is practically independent of the multilayer thickness. The magnetic
damping parameter , estimated from the linear dependence of the
linewidth, , on frequency, in the field in-plane geometry,
increases with decreasing . This behaviour is attributed to an enhancement
of spin-orbit interactions with decreasing and in thinner films, to a
spin-pumping contribution to the damping.Comment: 18 pages, 13 figure
Nanoscale temperature measurements using non-equilibrium Brownian dynamics of a levitated nanosphere
Einstein realised that the fluctuations of a Brownian particle can be used to
ascertain properties of its environment. A large number of experiments have
since exploited the Brownian motion of colloidal particles for studies of
dissipative processes, providing insight into soft matter physics, and leading
to applications from energy harvesting to medical imaging. Here we use
optically levitated nanospheres that are heated to investigate the
non-equilibrium properties of the gas surrounding them. Analysing the sphere's
Brownian motion allows us to determine the temperature of the centre-of-mass
motion of the sphere, its surface temperature and the heated gas temperature in
two spatial dimensions. We observe asymmetric heating of the sphere and gas,
with temperatures reaching the melting point of the material. This method
offers new opportunities for accurate temperature measurements with spatial
resolution on the nanoscale, and a new means for testing non-equilibrium
thermodynamicsComment: 5 pages, 4 figures, supplementary material available upon reques
Molecular characterization of porcine circovirus 2 isolated from diseased pigs co-infected with porcine reproductive and respiratory syndrome virus
In this study, we isolated a porcine circovirus 2 (PCV2) strain from piglets co-infected with porcine reproductive and respiratory syndrome virus (PRRSV). The complete genome of this strain was sequenced, phylogenetic and polymorphic analyses were carried out. BLAST searches revealed the highest sequence identity (99.5% nt and 99.3% aa) to Guangxi strain EF675230. The phylogenetic tree showed that clustering of the isolates didn't strongly correlate to geographical distribution. Polymorphic analyses demonstrated that the amino acids at most of the polymorphic sites in Open Reading Frame 1(ORF1) and 2 (ORF2)belong to the same amino acid group according to chemical or structural properties, and revealed that highly polymorphic regions overlapped with the known immunoreactive epitopes of ORF2
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