9,535 research outputs found
No-moving-part hybrid-synthetic jet actuator
In contrast to usual synthetic jets, the “hybrid-synthetic jets” of non-zero timemean nozzle mass flow rate are increasingly often considered for control of flow
separation and/or transition to turbulence as well as heat and mass transfer. The paper describes tests of a scaled-up laboratory model of a new actuator version, generating the hybrid-synthetic jets without any moving components. Self-excited flow oscillation is produced by aerodynamic instability in fixed-wall cavities. The return flow in the exit nozzles is generated by jet-pumping effect. Elimination of the delicate and easily damaged moving parts in the actuator simplifies its manufacture and assembly. Operating frequency is adjusted by the length of feedback loop path. Laboratory investigations concentrated on the propagation processes taking place in the loop
The A-decomposability of the Singer construction
Let denote the Singer construction on an unstable module over the
Steenrod algebra at the prime two; is canonically a subobject of
, where is the polynomial algebra on s generators of degree
one. Passage to -indecomposables gives the natural transformation , which identifies with the dual of the
composition of the Singer transfer and the Lannes-Zarati homomorphism.
The main result of the paper proves the weak generalized algebraic spherical
class conjecture, which was proposed by the first named author. Namely, this
morphism is trivial on elements of positive degree when s>2. The condition s>2
is necessary, as exhibited by the spherical classes of Hopf invariant one and
those of Kervaire invariant one.Comment: v2 15 pages. Minor revision. v3 17 pages, revision following
referee's recommendations. Accepted for publication J. Al
Super-Poissonian noise in a Coulomb blockade metallic quantum dot structure
The shot noise of the current through a single electron transistor (SET),
coupled capacitively with an electronic box, is calculated, using the master
equation approach. We show that the noise may be sub-Poissonian or strongly
super-Poissonian, depending mainly on the box parameters and the gate. The
study also supports the idea that not negative differential conductance, but
charge accumulation in the quantum dot, responds for the super-Poissonian noise
observed.Comment: 4 Pages, 3 Figure
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