On-line writing identical and weak fiber Bragg grating arrays

We investigate the on-line writing identical fiber Bragg grating (FBG) arrays using the phase mask technique. Given the limitation of laser power, the energy density uniformity and the horizontal width of the writing spot cannot be further optimized. The results show that the FBG arrays obtained in the optimal process (drawing speed of 12 ± 0.15 m/min and average tension of 38.2 g) have a central wavelength bandwidth of less than 0.1 nm and an average reflectivity of 0.26%. Thus, the phase mask method is a promising alternative for on-line writing identical FBG arrays.On-line writing identical and weak fiber Bragg grating arrays.     

Convergence issues in using high‐resolution schemes and lower–upper symmetric Gauss–Seidel method for steady shock‐induced combustion problems

This paper reports numerical convergence study for simulations of steady shock‐induced combustion problems with high‐resolution shock‐capturing schemes. Five typical schemes are used: the Roe flux‐based monotone upstream‐centered scheme for conservation laws (MUSCL) and weighted essentially non‐oscillatory (WENO) schemes, the Lax–Friedrichs splitting‐based non‐oscillatory no‐free parameter dissipative (NND) and WENO schemes, and the Harten–Yee upwind total variation diminishing (TVD) scheme. These schemes are implemented with the finite volume discretization on structured quadrilateral meshes in dimension‐by‐dimension way and the lower–upper symmetric Gauss–Seidel (LU–SGS) relaxation method for solving the axisymmetric multispecies reactive Navier–Stokes equations. Comparison of iterative convergence between different schemes has been made using supersonic combustion flows around a spherical projectile with Mach numbers M = 3.55 and 6.46 and a ram accelerator with M = 6.7. These test cases were regarded as steady combustion problems in literature. Calculations on gradually refined meshes show that the second‐order NND, MUSCL, and TVD schemes can converge well to steady states from coarse through fine meshes for M = 3.55 case in which shock and combustion fronts are separate, whereas the (nominally) fifth‐order WENO schemes can only converge to some residual level. More interestingly, the numerical results show that all the schemes do not converge to steady‐state solutions for M = 6.46 in the spherical projectile and M = 6.7 in the ram accelerator cases on fine meshes although they all converge on coarser meshes or on fine meshes without chemical reactions. The result is based on the particular preconditioner of LU–SGS scheme. Possible reasons for the nonconvergence in reactive flow simulation are discussed.Copyright © 2012 John Wiley & Sons, Ltd.     

The Discrete Subgroups and Jфrgensen’s Inequality for SL(m,Cp)

In this paper, we give discreteness criteria of subgroups of the special linear group on Qp or Cp in two and higher dimensions. J rgensen's inequality gives a necessary condition for a nonelementary group of Mbius transformations to be discrete. We give a version of Jфrgensen's inequality for SL(m, Cp).     

Analytical predictions of shapes of laminar diffusion flames in microgravity and earth gravity

Flame shape is an important observed characteristic of flames that can be used to scale flame properties such as heat release rates and radiation. Flame shape is affected by fuel type, oxygen levels in the oxidiser, inverse burning and gravity. The objective of this study is to understand the effect of high oxygen concentrations, inverse burning, and gravity on the predictions of flame shapes. Flame shapes are obtained from recent analytical models and compared with experimental data for a number of inverse and normal ethane flame configurations with varying oxygen concentrations in the oxidiser and under earth gravity and microgravity conditions. The Roper flame shape model was extended to predict the complete flame shapes of laminar gas jet normal and inverse diffusion flames on round burners. The Spalding model was extended to inverse diffusion flames. The results show that the extended Roper model results in reasonable predictions for all microgravity and earth gravity flames except for enhanced oxygen normal diffusion flames under earth gravity conditions. The results also show trends towards cooler flames in microgravity that are in line with past experimental observations. Some key characteristics of the predicted flame shapes and parameters needed to describe the flame shape using the extended Roper model are discussed.     

Multilayer Films with Nanocontainers: Redox‐Controlled Reversible Encapsulation of Guest Molecules

Stable multilayer films with cucurbit[8]uril have been fabricated on the basis of the alternating layer‐by‐layer assembly of a novel side‐chain pseudopolyrotaxane and a photoreactive polyanion. The as‐prepared multilayer films exhibit good properties as surface‐imprinted multilayers, because cucurbit[8]uril molecules that are locked inside the multilayers can act as nanocontainers with specific binding to certain guest molecules, and the loading and release of the guest is redox‐controllable and reversible.     

Synthesis of tetrazole containing 1,2,3-thiadiazole derivatives via U-4CR and their anti-TMV activity

A series of novel tetrazole containing 1,2,3-thiadiazole derivatives were designed and synthesized via Ugi reaction. Their structures were confirmed by melting points, IR, 1H NMR, and HRMS (ESI). Preliminary bioassay indicated that most target compounds exhibited very good direct anti-TMV activity at 100 μg/mL, which was equal to or higher than that of ribavirin. Among them, compounds 4b, 4c and 4i also showed equivalent protection effect to ribavirin in vivo at 100 μg/mL.     

Vesicle formation between single-chained cationic surfactants and ribo-oligonucleotides

Recently,we reported that deoxyribo-oligonucleotides could induce single chained cationic surfactant aggregation to form vesicles.In this paper,we will present that ribo-oligonucleotides can also induce vesicle formation,and compared with deoxyribo-oligonucleotides,ribo-oligonucleotides exhibit a higher inductive efficiency.