Emergence of semi-localized Anderson modes in a disordered photonic crystal as a result of overlap probability

In this paper we study the effect of positional randomness on transmissional properties of a two dimensional photonic crystal as a function of a randomness parameter $\alpha$ ($\alpha=0$ completely ordered, $\alpha=1$ completely disordered). We use finite-difference time-domain~(FDTD) method to solve the Maxwell's equations in such a medium numerically. We consider two situations: first a 90\degr bent photonic crystal wave-guide and second a centrally pulsed photonic crystal micro-cavity. We plot various figures for each case which characterize the effect of randomness quantitatively. More specifically, in the wave-guide situation, we show that the general shape of the normalized total output energy is a Gaussian function of randomness with wavelength-dependent width. For centrally pulsed PC, the output energy curves display extremum behavior both as a function of time as well as randomness. We explain these effects in terms of two distinct but simultaneous effects which emerge with increasing randomness, namely the creation of semi-localized modes and the shrinking (and eventual destruction) of the photonic band-gaps. Semi-localized (i.e. Anderson localized) modes are seen to arise as a synchronization of internal modes within a cluster of randomly positioned dielectric nano-particles. The general trend we observe shows a sharp change of behavior in the intermediate randomness regime (i.e. $\alpha \approx 0.5$) which we attribute to a similar behavior in the underlying overlap probability of nano-particlesComment: New published version with a new title. This article is featured on the cover of the corresponding journal (Nov. issue of EJPB

Rosiglitazone and glimeperide: review of clinical results supporting a fixed dose combination

Type 2 diabetes has become a major burden to the health care systems worldwide. Among the drugs approved for this indication, glimepiride and rosiglitazone have gained substantial importance in routine use. While glimepiride stimulates β-cell secretion and leads to reduction of blood glucose values, rosiglitazone activates PPARγ and improves insulin resistance, at the vascular and metabolically active cells. Therefore, the combination of the two drugs may be an interesting approach to improve glycemic control and lower cardiovascular risk. A fixed combination of both drugs has been approved for clinical use in the US and EU. The combination of glimepiride and rosiglitazone is generally well tolerated and the use of a fixed combination may lead to improved adherence of the patients to their therapy. The purpose of this review is to evaluate the clinical data that have been published on this combination, appearing to represent a convenient way to obtain therapeutic targets in patients with type 2 diabetes mellitus

Status of Turbulence Modeling for Hypersonic Propulsion Flowpaths

This report provides an assessment of current turbulent flow calculation methods for hypersonic propulsion flowpaths, particularly the scramjet engine. Emphasis is placed on Reynolds-averaged Navier-Stokes (RANS) methods, but some discussion of newer meth- ods such as Large Eddy Simulation (LES) is also provided. The report is organized by considering technical issues throughout the scramjet-powered vehicle flowpath including laminar-to-turbulent boundary layer transition, shock wave / turbulent boundary layer interactions, scalar transport modeling (specifically the significance of turbulent Prandtl and Schmidt numbers) and compressible mixing. Unit problems are primarily used to conduct the assessment. In the combustor, results from calculations of a direct connect supersonic combustion experiment are also used to address the effects of turbulence model selection and in particular settings for the turbulent Prandtl and Schmidt numbers. It is concluded that RANS turbulence modeling shortfalls are still a major limitation to the accuracy of hypersonic propulsion simulations, whether considering individual components or an overall system. Newer methods such as LES-based techniques may be promising, but are not yet at a maturity to be used routinely by the hypersonic propulsion community. The need for fundamental experiments to provide data for turbulence model development and validation is discussed

Boundary layer suction modeling based on the DLR TAU-Code effusion mass flux boundary condition

The aeroelastic assessment of hybrid laminar flow control systems for transport aircraft requires well suited computational models to represent the suction system. This paper presents the application of a non-zero wall-normal velocity boundary condition in the DLR TAU-Code to model an active suction system for laminar flow control. First, the computational laminar velocity profile on a flat plate with homogeneous suction is compared to the analytical solution. Second, the suction boundary condition is tested in combination with a correlation-based transition model and compared to experimental data for a NACA airfoil. In addition, a generic test case is used to demonstrate the effect of a suction system on the steady and unsteady aerodynamics of an airfoil in a transonic, high Reynolds number flow

Towards CFD-based Aeroelastic Analysis of NLF Wings

The effect of Natural Laminar Flow (NLF) on the aeroelastic behavior of transport aircraft wings is widely unknown. This numerical study investigates the influence of boundary layer transition on the unsteady aerodynamic response of an NLF test case, the DLR-F5 wing. State-of-the-art RANS methods for transition prediction are compared at wind tunnel and free-flight conditions. A more critical flutter behavior is indicated in the case of transitional flow