34,668 research outputs found
Characterisation of the cold metal transfer (CMT) process and its application for low dilution cladding
The process characteristics of the synergic cold metal transfer (CMT) process
have been examined for welding aluminium alloy. Utilising a simple backlighting
system and through the arc monitoring the droplet transfer modes were
identified. Whilst the modified short circuit mode was evident for the lower
parameter range, a two part transfer mode based upon a combination of spray and
short circuit transfer was observed for the mid to upper parameter range. The
technology was also explored as a cladding process for applying to ternary
alloyed (Al–Cu–Mg) aluminium plate. This alloy system is known to be susceptible
to solidification cracking when MIG welded using the binary Al-2319 (Al–Cu)
filler wire, this being due to the wide element freezing range of the weld
resulting from mixing with the base material. Utilising this filler, weld
dilution ratios for both CMT and pulsed welding were identified across the
examined parameter range. The CMT process exhibited greater control of dilution
that enabled deposition of a quasi-binary (Al–Cu) layer exhibiting a less crack
susceptible composition. Onto this layer conventional MIG welding could be
applied which could potentially eradicate cracking using a binary fi
Supercharged topping rocket propellant feed system
A rocket propellant feed system utilizing a bleed turbopump to supercharge a topping turbopump is presented. The bleed turbopump is of a low pressure type to meet the cavitation requirements imposed by the propellant storage tanks. The topping turbopump is of a high pressure type and develops 60 to 70 percent of the pressure rise in the propellant
Morphology investigation on direct current pulsed gas tungsten arc welded additive layer manufactured Ti6Al4V alloy
The effects of pulsed gas tungsten arc weldingparameters on the morphology of
additive layer manufacturedTi6Al4V has been investigated in this study. Thepeak/
base current ratio and pulse frequency are found tohave no significant effect on
the refinement of prior betagrain size. However, it is found that the wire feed
ratehas a considerable effect on the prior beta grainrefinement at a given heat
input. This is due to the extrawire input being able to supply many
heterogeneousnucleation sites and also results in a negative temperaturegradient
in the front of the liquidus which blocks thecolumnar growth and changes the
columnar growth toequiaixal growth
Portable, high intensity isotopic neutron source provides increased experimental accuracy
Small portable, high intensity isotopic neutron source combines twelve curium-americium beryllium sources. This high intensity of neutrons, with a flux which slowly decreases at a known rate, provides for increased experimental accuracy
Scattering of 42 MeV /6.7-pJ/ alpha particles from even isotopes of cadmium. Supplement 1 - Absolute cross sections
Absolute cross sections for scattering of 42 MeV alpha particles from even isotopes of cadmiu
Elastic and inelastic scattering of 42-MeV alpha particles from even tellurium isotopes
Angular distributions of elastic and inelastic scattering of 42-MeV alpha particles measured for even tellurium isotope
A Precision Model Independent Determination of |Vub| from B -> pi e nu
A precision method for determining |Vub| using the full range in q^2 of B->
pi \ell nu data is presented. At large q^2 the form factor is taken from
unquenched lattice QCD, at q^2=0 we impose a model independent constraint
obtained from B-> pi pi using the soft-collinear effective theory, and the
shape is constrained using QCD dispersion relations. We find |Vub| =(3.54\pm
0.17\pm 0.44) x 10^{-3}. With 5% experimental error and 12% theory error, this
is competitive with inclusive methods. Theory error is dominated by the input
points, with negligible uncertainty from the dispersion relations.Comment: 4 pages, 3 figure
Constraint equations for heavy-to-light currents in SCET
A complete basis for the next-to-next-to leading order heavy-to-light
currents in the soft-collinear effective theory is constructed.
Reparameterization invariance is imposed by deriving constraint equations.
Their solutions give the set of allowed Dirac structures as well as relations
between the Wilson coefficients of operators that appear at different orders in
the power expansion. The completeness of reparameterization invariance
constraints derived on a projected surface is investigated. We also discuss the
universality of the ultrasoft Wilson line with boundary conditions.Comment: 35 page
Spin tests of a single-engine, high-wing light airplane
The airplane has a relatively steep spin mode (low angle of attack) with a high load factor and high velocity. The airplane recovers almost immediately after any deviation from the prospin control positions, except for one maneuver with reduced flexibility in the elevator control system
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