Previous studies have shown that the formation of coherent vortex rings in the nearwake of a self-propelled vehicle can increase propulsive efficiency compared with a steady jet wake. The present study utilizes a self-propelled vehicle to explore the dependence of propulsive efficiency on the vortex ring characteristics. The maximum propulsive efficiency was observed to occur when vortex rings ...

We have investigated the magnetization reversal mechanism of narrow submicrometer Co rings using scanning magnetoresistance microscopy. Thermal annealing in a magnetic field introduced a uniaxial anisotropy and significant structural changes in the samples. We have observed a complicated multidomain state at intermediate field ranges, and onion states at saturation, for samples annealed in a fi...

By using terahertz time-domain spectroscopy and rigorous simulations, we investigate the impact of gap orientation of neighboring split rings on the three lowest order eigenmodes for a metamaterial based on split ring resonators. We distinct scenarios where neighboring split rings have their gap either on the same or on opposite sides. The two lowest order eigenmodes are marginally affected, wh...

We call a module  essentially retractable if HomR for all essential submodules N of M. For a right FBN ring R, it is shown that: (i)  A non-zero module  is retractable (in the sense that HomR for all non-zero ) if and only if certain factor modules of M are essentially retractable nonsingular modules over R modulo their annihilators. (ii)  A non-zero module  is essentially retractable if and on...

We use Dieudonné theory for periodically graded Hopf rings to determine the Dieudonné ring structure of the Z/2(pn − 1)-graded Morava K-theory K(n)∗(−), with p an odd prime, when applied to the Ω-spectrum k(n) ∗ (and to K(n) ∗ We also expand these results in order to accomodate the case of the full Morava K-theory K(n)∗(−).

let $r$ be a reversible ring which is $alpha$-compatible for an endomorphism $alpha$ of $r$ and $f(x)=a_0+a_1x+cdots+a_nx^n$ be a nonzero skew polynomial in $r[x;alpha]$. it is proved that if there exists a nonzero skew polynomial $g(x)=b_0+b_1x+cdots+b_mx^m$ in $r[x;alpha]$ such that $g(x)f(x)=c$ is a constant in $r$, then $b_0a_0=c$ and there exist nonzero elements $a$ and $r$ in $r$ such tha...

in this paper, we introduce the concept of the   generalized aip-rings as a generalization of the generalized quasi-   baer rings   and generalized p.p.-rings. we show that the class of the generalized aip-rings is closed under direct products and morita invariance. we also characterize the 2-by-2 formal upper triangular matrix rings of this new class of rings. finally, we provide sever...