Multipolar-sensitive engineering of magnetic dipole spontaneous emission with a dielectric nanoresonator antenna

We propose an axisymmetric silicon nanoresonator with designed tapered angle well for the extraordinary enhancement of the decay rate of magnetic dipole (MD) emitters. Due to the resonant coupling of a MD emitter and the MD mode of the subwavelength resonator, the Purcell factor (PF) can easily reach 500, which is significantly higher than the PF when using a silicon nanosphere of the same size. The PF and the resonance frequency are conveniently tuned through the resonator diameter and the taper angle of the blind hole. When supported by a metallic substrate, further enhancement ($$>10^3$$ > 10 3 ) of the MD spontaneous emission is triggered by an image-induced quadrupolar high-Q mode of the nanoantenna. For the sake of comparison we include a critical analysis of the canonical problem that considers a Si spherical shell. Our results might facilitate a novel strategy for promising realizations of chip-scale nanophotonic applications.

Thermodynamic analysis in bubbling fluidized bed dryers with spiral and cone angles

The effective thermodynamic analysis is quite necessary for proper system design performance and optimization of system processes. Energy is concerned with the quantitative evaluation of system processes. Nonetheless, exergy gives a qualitative analysis of the system processes. The present investigation deals with the study of exergy and energy analysis of the paddy drying processes in two tapered fluidized bed dryers having tapered angle 5° and 10° respectively and one cylindrical bubbling fluidized bed dryer. The energy utilization (EU) and energy utilization ratio (EUR) for various operating parameters such as inlet air velocity, mass of paddy, temperature, a spiral and cone angle are investigated. Similar to that, the exergetic efficiency and the rate of exergy destruction are also studied for the same operating parameters. The EU and EUR are found to have an increasing order when the inlet air velocity, temperature and mass of paddy increase. The trend of EU and EUR also increase with an addition of a spiral inside a dryer. The increasing cone angle of dryer have a similar impact on EU and EUR. Similarly, exergy utilization and exergetic efficiency also show an increment with the rise in inlet air velocity, mass of paddy, cone angle of dryer and temperature. Incorporation of a spiral inside a dryer improves exergy utilization and exergetic efficiency. Hence, conical dryer with higher cone angle is found to be the best option for drying.

Combination of Taper and Hierarchy to Improve Crushing Efficiency of Thin-Walled Tubes

To improve the energy absorption capacity of thin-walled tubular structures and simultaneously reduce their initial peak force (IPF), hierarchical hexagonal tapered tube (HHTT) is proposed combining advantages of the hierarchical hexagonal tube (HHT) and the tapered tube (TT), for HHTs can greatly improve the mean crushing force (MCF) while TTs can reduce the IPF. Crushing behaviors of HHTTs under quasi-static compression are investigated through numerical simulations and theoretical analyses. According to the folding modes, a theory to predict the MCF of the HHTT is proposed. According to the research, it is found that the combination of hierarchy and tapering improves the MCF of the tubular structure and the crushing force efficiency (CFE), defined by the ratio of the MCF to the IPF. It is also found that increasing the tapered angle, the wall thickness and the cell number of the lattice wall can effectively improve the CFE of the HHTT.

PERFORMANCE OF AXIALLY LOADED TAPERED CONCRETE-FILLED STEEL COMPOSITE SLENDER COLUMNS

This paper focuses on the performance of a special kind of tapered composite columns, namely tapered concrete-filled steel composite (TCFSC) slender columns, under axial loading. These efficient TCFSC columns are formed by the increase of the mid-height depth and width of straight concrete-filled steel composite (CFSC) slender columns, that is, by the enhancement of the tapered angle (from 0° to 2.75°) of the tapered composite columns from their top and bottom to their mid-height. To investigate the performance of the columns, finite element software LUSAS is employed to carry out the nonlinear analyses. Comparisons of the nonlinear finite element results with the existing experimental results uncover the reasonable accuracy of the proposed modelling. Nonlinear analyses are extensively performed and developed to study effects of different variables such as various tapered angles, steel wall thicknesses, concrete compressive strengths, and steel yield stresses on the performance of the columns. It is concluded that increasing each of these variables considerably enhances the ultimate axial load capacity. Also, enhancement of the tapered angle and/or steel wall thickness significantly improves the ductility. Moreover, confinement effect of the steel wall on the performance of the columns is evaluated. Failure modes of the columns are also presented.

Simulation Study on Tapered and Spherical Shaped Charge under Underwater Explosion

For improving the damage effect to underwater target of warhead, a kind of metamorphic tapered angle shaped charge is designed, and the damge mechanism is analyzed. The physics modle of tapered and spherical shaped charge under underwater explosion is built, numerical simulation is done by LS-DYNA, the stress distribution and velocity of jet are got. The result shows that the shaped charge jet formed by this kind of structure can provide moving space for latter EFP, which improving the damage effect to target.