Effect of Process Parameters on Mode Conversion in Submicron Tapered Silicon Ridge Waveguides

The modal property and light propagation in tapered silicon ridge waveguides with different ridge heights are investigated for a silicon on insulator (SOI) platform with a 500 nm silicon (Si) thickness. Mode conversion between the transverse magnetic (TM) fundamental and higher-order transverse electric (TE) modes occurs when light is propagated in a waveguide taper. Such a conversion is due to mode hybridization resulting from the vertical asymmetry of the cross-section in the ridge waveguides. The influence of angled sidewalls and asymmetric cladding on mode conversion is also studied. It is shown that a very long taper length (adiabatic) is required for a complete conversion to take place. Conversely, such mode conversion could be suppressed by designing a short non-adiabatic taper. Our results show that significant improvement in performance metrics can be achieved by considering process parameters’ effect on mode conversion. With an optimum selection of the etching depth and accounting asymmetries due to angled sidewalls and cladding, we demonstrate an 84.7% reduction in taper length (adiabatic) for mode conversion and a 97% efficiency TM preserving taper (ultra-short). The analysis is essential for applications such as compact polarizers, polarization splitters/rotators, and tapers for TM devices.

No Trouble

Eric Wielenberg’s two alleged contradictions in my view of God, time, and creation are easily resolved. The first is dissolved by appreciating that God’s power to create the universe is a modal property which God may possess but even if He never in fact exercises that power. The second contradiction evaporates once one adopts a relational view of time.

Dynamic Modeling and Stability Analysis of a Dual-Rotor Wind Turbine

Various modal analysis methods are available for single-rotor wind turbines, but there is no report and guidance on the modal property analysis of multi-rotor wind turbines. This paper presents a dynamic modeling method for the modal response analysis of a wind turbine with two three-bladed isotropic rotors. The equations of motion are derived using Lagrange’s equations and are further linearized at a steady-state equilibrium. To avoid using Floquet Theory to remove the periodic coefficients, multi-blade coordinates are utilized. Comparison between the numerical simulations and a high-fidelity model in HAWC2 shows agreements in terms of modal frequencies. The results shows that the whirling modes splits into symmetric and asymmetric rotor modes.

Adjectival 'as'-phrases as intensional secondary predicates

This paper focuses on adjectival as-phrases that co-occur with transitive verbs, and contribute additional information on the verb’s internal arguments. I claim that these as-phrases behave like secondary predicates, specifically object-oriented depictives, but—in contrast to object-oriented depictives—contribute intensional content, a modal property. In the course of the paper, I delimit the type of as-phrases that are covered in this paper, and propose a formal analysis for these cases that builds on results by Rothstein (2003) on object-oriented depictives, and the notion of information-based modality in Kratzer 2012. I show how the analysis captures the entailment patterns found with these as-phrases, and how it can be extended to related nominal as-phrases.

Taguchi Robust Design of Exhaust System Based on the Parametrically Process of Parts Location

Due to the change of car-body design, the location of exhaust systems hanger is uncertain and always fluctuates around the initial design position. So the Taguchi method is introduced to conduct exhaust systems optimal design. Firstly, the parameterization of hanger location under the grid environment was realized by combining NastranHypermesh and Isight. Then, the Taguchi robust design of the exhaust system is performed taking the hanger location as noise factors and the stiffness of hanger shock absorber as control factors. As a result, modal property and robustness of the exhaust system are improved. At last, the results of Taguchi robust design and traditional sensitivity optimization design based on the finite element method are compared, which reveals the advantage of Taguchi robust design in improving product quality.