General background of the application of the CVT:by example of the VDT EcoDrive transmission

A further reduction of fuel consumption, while maintaining or even improving driveability andperformance, is the primary aim of VDT’s EcoDrive project. The general designconsiderations that led to the newest push-belt based CVT forms the topic of the presentpaper. The following items are covered: transmission layout, fuel consumption map, ratiocoverage, variator clamping strategy and engine speed control. Measurements on a testvehicle are presented. This paper is intended to present the relevant results influencing theprimary project targets: fuel consumption and driveability improvement

Investigation of the tunneling emitter bipolar transistor as spin-injector into silicon

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 185-196).In this thesis is discussed the tunneling emitter bipolar transistor as a possible spin-injector into silicon. The transistor has a metallic emitter which as a spin-injector will be a ferromagnet. Spin-polarized electrons from the ferromagnet tunnel directly into the conduction band of the base of the transistor and are subsequently swept into the collector. The tunneling emitter bipolar transistor as a spin-injector allows for large spin-polarized currents and naturally overcomes the conductivity mismatch and Schottky barrier formation. In this work, the various aspects of the transistor are analyzed. The transfer of spin-polarization across the base-collector junction is simulated. The oxide MgO is considered as a tunnel barrier for the transistor. Electron spin resonance is proposed as a measurement technique to probe the spin-polarization injected into the collector. The fabrication of the transistors is discussed and the importance of the tunnel barrier for the device operation is fully analyzed. The observation of negative differential transconductance in the transistor is explained. A number of side- or unrelated studies are presented as well. A study on scattered and secondary electrons in e-beam evaporation is described. Spin-orbit coupling induced spin-interference of ring-structures is proposed as a spin-detector. A new measurement technique to probe bias dependent magnetic noise in magnetic tunnel junctions is proposed. Also, an IV fitting program that can extract the relative importance of the tunnel and Schottky barrier is discussed and employed to fit the base-emitter IV characteristics of the transistor. The development of several fabrication and experimental tools is described as well.by Marc Julien van Veenhuizen.Ph.D

Spin-orbit induced interference in polygon-structures

We investigate the spin-orbit induced spin-interference pattern of ballistic electrons travelling along any regular polygon. It is found that the spin-interference depends strongly on the Rashba and Dresselhaus spin-orbit constants as well as on the sidelength and alignment of the polygon. We derive the analytical formulae for the limiting cases of either zero Dresselhaus or zero Rashba spin-orbit coupling, including the result obtained for a circle. We calculate the nonzero Dresselhaus and Rashba case numerically for the square, triangle, hexagon, and circle and discuss the observability of the spin-interference which can potentially be used to measure the Rashba and Dresselhaus coefficients.Comment: 17 pages, 4 figure