Volume current method for analysis of tilted fiber gratings

An analytic approach to calculate the radiation pattern (including the wavelength dependence, azimuthal distribution, and polarization dependence) of tilted fiber phase gratings using the volume current method (VCM) is introduced in this paper. Results for both uniform and apodized fiber gratings are derived and discussed, and a brief comparison to experimental measurements from practical devices is also made     

Compression after low-velocity impact (CAI) properties of multistitched composites

The objective of this work was to investigate compression after low-velocity impact (CAI) properties of a multistitched composite. It was found that the CAI strength of the multistitched composite was high compared to the unstitched composites. In addition, stitching density, stitching type, stitching direction, and stitching fibers were found to be important structural parameters. The CAI load on the multistitched composites resulted in lateral damages near the impacted indentation region. The structures showed large damaged areas, but the out-of-plane layer delamination was confined to relatively small areas. Thus, the multistitching enhanced the CAI properties of the composite.     

Scattering characteristics of a rectangular groove in a reactivesurface

The diffraction of a plane electromagnetic wave by a rectangular groove in a reactive plane is studied rigorously through the Fourier transform technique. The corresponding boundary value problem is formulated into a modified Wiener-Hopf equation of the third kind whose approximate solution involves two sets of infinite number of unknown constants satisfying two infinite systems of linear algebraic equations. Numerical solutions of these systems are obtained for various values of the surface reactance and the sizes of the groove through which the effects of these parameters on the diffraction phenomenon are studied     

Packaged hybrid soliton pulse source results 70 terabit.km/secsoliton transmission

A packaged hybrid soliton pulse source is used in a soliton transmission experiment employing sliding-frequency guiding filters. The source shows excellent stability and very clean tuning characteristics. Control of the operating frequency and wavelength are described. Error free transmission at 10 GBit/s is achieved over a distance of 27000 km     

Simultaneous wavelength-stabilization of 980-nm pump lasers

High power 980-nm strained QW semiconductor lasers connected to the input ports of a 4×4-fused fiber star coupler are simultaneously wavelength-locked through reflection from a single narrow-band fiber grating connected to one output port. This configuration enables simple pump wavelength control, inhibits deleterious pump-laser interactions, and improves amplifier reliability through pump redundancy     

Four channel fibre grating demultiplexer

The authors demonstrate a four channel all-fibre demultiplexer based on a 1×4 fused fibre coupler followed by strong fibre grating passband filters     

Rate and selectivity modification in fischer—tropsch synthesis over charcoal supported molybdenum by forced concentration cycling

Forced concentration cycling of the feed between pure CO and pure H₂ was used to successfully change both the selectivities and reactivities of promoted and unpromoted charcoal supported molybdenum catalysts in Fischer-Tropsch synthesis. It was found that with the unpromoted catalyst the rate enhancement increases with temperature and selectivity shifts towards methane. At the lower temperatures concentration cycling increases selectivity to ethane and higher hydrocarbons to levels only achievable with promoted catalysts. Periodic operation with the potassium promoted catalyst results in small rate enhancements but the olefin to paraffin ratio is dramatically changed without changing the carbon number distribution.     

Interface crack problems in graded orthotropic media: Analytical and computational approaches

Interface crack problems in graded orthotropic media are considered using analytical and computational techniques. In the analytical formulation an interface crack between a graded orthotropic coating and a homogeneous orthotropic substrate is considered. The principal axes of orthotropy are assumed to be parallel and perpendicular to the crack plane. Mechanical properties of the medium are assumed to be continuous with discontinuous derivatives at the interface. The problem is formulated in terms of the averaged constants of plane orthotropic elasticity and reduced to a pair of singular integral equations which are solved numerically to compute the mixed mode stress intensity factors and the energy release rate. In the second part of the study, enriched finite elements are formulated and implemented for graded orthotropic materials. Comparisons of the finite element and analytical results show that enriched finite element technique is capable of producing highly accurate results for crack problems in graded orthotropic media. Finally, periodic interface cracking and the four point bending test for graded orthotropic solids are modeled using enriched finite elements and the results are briefly discussed.