Numerical analysis of a downsized 2-stroke uniflow engine

In order to optimize the 2-stroke uniflow engine performance on vehicle applications, numerical analysis has been introduced, 3D CFD model has been built for the optimization of intake charge organization. The scavenging process was investigated and the intake port design details were improved. Then the output data from 3D CFD calculation were applied to a 1D engine model to process the analysis on engine performance. The boost system optimization of the engine has been carried out also. Furthermore, a vehicle model was also set up to investigate the engine in-vehicle performance

On Magnetic Interlayer Coupling and Proximity Effect in a La0.67_{0.67}Ca0.33_{0.33}MnO3_3(10 nm)/YBa2_2Cu3_3O7_7(10 nm) Superlattice

We present a study of interlayer coupling and proximity effects in a La$_{0.66}$Ca$_{0.33}$MnO$_3$(10 nm)/YBa$_2$Cu$_3$O$_7$(10 nm) superlattice. Using element-sensitive x-ray probes, the magnetic state of Mn can be probed without seeing the strong diamagnetism of the superconductor, which makes this approach ideal to study changes in the magnetic properties across the superconducting transition. By a combined experiment using {\it in situ} transport measurements during polarized soft x-ray measurements, we were able to see no noticeable influence of the superconducting state on the magnetic properties and no evidence for magnetic coupling across a 10 nm YBCO layer.Comment: 4 pages, submitted to Applied Physics Letter

Induced Ge Spin Polarization at the Fe/Ge Interface

We report direct experimental evidence showing induced magnetic moments on Ge at the interface in an Fe/Ge system. Details of the x-ray magnetic circular dichroism and resonant magnetic scattering at the Ge L edge demonstrate the presence of spin-polarized {\it s} states at the Fermi level, as well as {\it d} character moments at higher energy, which are both oriented antiparallel to the moment of the Fe layer. Use of the sum rules enables extraction of the L/S ratio, which is zero for the {\it s} part and $\sim0.5$ for the {\it d} component. These results are consistent with layer-resolved electronic structure calculations, which estimate the {\it s} and {\it d} components of the Ge moment are anti-parallel to the Fe {\it 3d} moment and have a magnitude of $\sim0.01 \mu_B$.Comment: 4 pages, 5 figures, submitted to Phys. Rev. Let

Full Bulk Spin Polarization and Intrinsic Tunnel Barriers at the Surface of Layered Manganites

Transmission of information using the spin of the electron as well as its charge requires a high degree of spin polarization at surfaces. At surfaces however this degree of polarization can be quenched by competing interactions. Using a combination of surface sensitive x-ray and tunneling probes, we show for the quasi-two-dimensional bilayer manganites that the outermost Mn-O bilayer, alone, is affected: it is a 1-nm thick insulator that exhibits no long-range ferromagnetic order while the next bilayer displays the full spin polarization of the bulk. Such an abrupt localization of the surface effects is due to the two-dimensional nature of the layered manganite while the loss of ferromagnetism is attributed to weakened double exchange in the reconstructed surface bilayer and a resultant antiferromagnetic phase. The creation of a well-defined surface insulator demonstrates the ability to naturally self-assemble two of the most demanding components of an ideal magnetic tunnel junction.Comment: 19 pages, 5 figure

Statistical observations of the trajectories of neutrally buoyant floats in the North Atlantic

This is a report of the statistical behavior of neutrally buoyant SOFAR floats, drifting at 1500 m depth in the Sargasso Sea where the currents are dominantly time-dependent. The float level is fairly typical of the deep ocean below the main thermocline...

Nanoscale Suppression of Magnetization at Atomically Assembled Manganite Interfaces

Using polarized X-rays, we compare the electronic and magnetic properties of a La(2/3)Sr(1/3)MnO(3)(LSMO)/SrTiO(3)(STO) and a modified LSMO/LaMnO(3)(LMO)/STO interface. Using the technique of X-ray resonant magnetic scattering (XRMS), we can probe the interfaces of complicated layered structures and quantitatively model depth-dependent magnetic profiles as a function of distance from the interface. Comparisons of the average electronic and magnetic properties at the interface are made independently using X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD). The XAS and the XMCD demonstrate that the electronic and magnetic structure of the LMO layer at the modified interface is qualitatively equivalent to the underlying LSMO film. From the temperature dependence of the XMCD, it is found that the near surface magnetization for both interfaces falls off faster than the bulk. For all temperatures in the range of 50K - 300K, the magnetic profiles for both systems always show a ferromagnetic component at the interface with a significantly suppressed magnetization that evolves to the bulk value over a length scale of ~1.6 - 2.4 nm. The LSMO/LMO/STO interface shows a larger ferromagnetic (FM) moment than the LSMO/STO interface, however the difference is only substantial at low temperature.Comment: 4 pages, 4 figure