Direct Observation of Large Amplitude Spin Excitations Localized in a Spin-Transfer Nanocontact

We report the direct observation of large amplitude spin-excitations localized in a spin-transfer nanocontact using scanning transmission x-ray microscopy. Experiments were conducted using a nanocontact to an ultrathin ferromagnetic multilayer with perpendicular magnetic anisotropy. Element resolved x-ray magnetic circular dichroism images show an abrupt onset of spin excitations at a threshold current that are localized beneath the nanocontact, with average spin precession cone angles of 25{\deg} at the contact center. The results strongly suggest that we have observed a localized magnetic soliton.Comment: 5 pages, 3 figure

On modelling and analysis of voxel-based force prediction for a 3-axis CNC machining

Determination of cutting forces is the main requirement for understanding the machining process and optimising its parameters for achieving higher productivity and surface finish. This paper presents an exploratory study and the development of a model to estimate cutting forces for a 3-axis CNC milling process using a voxel-based CAD model. The developed algorithm takes the NC code, workpiece/tool material properties, and the tool geometry data as inputs. The cutting tool engagement with the workpiece is computed using a discretized (voxelized) model. The calculated voxel engagement was finally used to calculate the cutting forces using the analytical method. The algorithm was implemented and tested for various case studies and the in-house experimental data for different types of end mill tools. Finally, the effect of variation in the size of the voxel and the number of flutes was studied. The model showed a good correlation and was found to be accurate (~80%) and robust.</p

Efficiency of liquid culture systems over conventional micropropagation: A progress towards commercialization

The most common methods of micropropagation involve the proliferation of shoots via a semi solid system. While such semi solid systems have been moderately to highly successful in terms ofmultiplication yields, it has become increasingly important to improve productivity and reduce the time taken to multiply commercially important material. Micropropagation by conventional techniques istypically a labor intensive time taking means of clonal propagation. To overcome this, the use of shake cultures utilizing liquid culture medium has been promoted. The liquid medium allows the close contactwith the tissue which stimulates and facilitates the uptake of nutrients and phytohormones, leading to better shoot and root growth. Continuous shaking promotes lesser expression of apical dominance which generally leads to induction and proliferation of numerous axillary buds. Further, with in the shake culture conditions, the growth and multiplication rate of shoots is enhanced by forced aeration,since continuous shaking of medium provides ample oxygen supply to the tissue which ultimately leads to their faster growth. Bioreactor provides a rapid and efficient clonal propagation systemutilizing liquid medium to avoid intensive manual handling. Automation of micropropagation in bioreactors has been advanced by several authors as a possible way of reducing cost of micropropagation. Micropropagation in bioreactors for optimal plant production depends upon better understanding of physiological and biochemical responses of plant to the signals of culture microenvironment and an optimization of specific physical and chemical culture conditions to controlthe morphogenesis of plants in liquid culture systems

Data-Based Model Refinement Using Retrospective Cost Optimization

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/83642/1/AIAA-2010-7889-194.pd