Pulsed-field magnetization of drilled bulk high-temperature superconductors: flux front propagation in the volume and on the surface

We present a method for characterizing the propagation of the magnetic flux in an artificially drilled bulk high-temperature superconductor (HTS) during a pulsed-field magnetization. As the magnetic pulse penetrates the cylindrical sample, the magnetic flux density is measured simultaneously in 16 holes by means of microcoils that are placed across the median plane, i.e. at an equal distance from the top and bottom surfaces, and close to the surface of the sample. We discuss the time evolution of the magnetic flux density in the holes during a pulse and measure the time taken by the external magnetic flux to reach each hole. Our data show that the flux front moves faster in the median plane than on the surface when penetrating the sample edge; it then proceeds faster along the surface than in the bulk as it penetrates the sample further. Once the pulse is over, the trapped flux density inside the central hole is found to be about twice as large in the median plane than on the surface. This ratio is confirmed by modelling.

100 Gigabit Ethernet transmission enabled by carrierless amplitude and phase modulation using QAM receivers

Simulations have investigated single laser 100G Ethernet links enabled by CAP-16 using QAM receivers that not only lower significantly system timing jitter sensitivity but also outperform PAM and standard CAP in terms of power margin. © 2013 OSA.

100 Gigabit ethernet transmission enabled by carrierless amplitude and phase modulation using QAM receivers

Simulations have investigated single laser 100G Ethernet links enabled by CAP-16 using QAM receivers that not only lower significantly system timing jitter sensitivity but also outperform PAM and standard CAP in terms of power margin. © 2013 OSA.

Aerodynamic design of high end wall angle turbine stages-part I: Methodology development

A design methodology is presented for turbines in an annulus with high end wall angles. Such stages occur where large radial offsets between the stage inlet and stage outlet are required, for example in the first stage of modern low pressure turbines, and are becoming more prevalent as bypass ratios increase. The turbine vanes operate within s-shaped ducts which result in meridional curvature being of a similar magnitude to the bladeto-blade curvature. Through a systematic series of idealized computational cases, the importance of two aspects of vane design are shown. First, the region of peak end wall meridional curvature is best located within the vane row. Second, the vane should be leant so as to minimize spanwise variations in surface pressure-this condition is termed "ideal lean." This design philosophy is applied to the first stage of a low pressure turbine with high end wall angles. © 2014 by ASME.

Aerodynamic design of high end wall angle turbine stages- part II: Experimental verification

An experimental investigation of a turbine stage featuring very high end wall angles is presented. The initial turbine design did not achieve a satisfactory performance and the difference between the design predictions and the test results was traced to a large separated region on the rear suction-surface. To improve the agreement between computational fluid dynamics (CFD) and experiment, it was found necessary to modify the turbulence modeling employed. The modified CFD code was then used to redesign the vane, and the changes made are described. When tested, the performance of the redesigned vane was found to have much closer agreement with the predictions than the initial vane. Finally, the flowfield and performance of the redesigned stage are compared to a similar turbine, designed to perform the same duty, which lies in an annulus of moderate end wall angles. A reduction in stage efficiency of at least 2.4% was estimated for the very high end wall angle design. © 2014 by ASME.

Comparison of moment-curvature models for fiber-reinforced polymer plate-end debonding studies using global energy balance approach

This paper compares a number of different moment-curvature models for cracked concrete sections that contain both steel and external fiber-reinforced polymer (FRP) reinforcement. The question of whether to use a whole-section analysis or one that considers the FRP separately is discussed. Five existing and three new models are compared with test data for moment-curvature or load deflection behavior, and five models are compared with test results for plate-end debonding using a global energy balance approach (GEBA). A proposal is made for the use of one of the simplified models. The availability of a simplified model opens the way to the production of design aids so that the GEBA can be made available to practicing engineers through design guides and parametric studies. Copyright © 2014, American Concrete Institute.