Morphology and phosphate distribution in bottom ash particles from fixed-bed co-combustion of sewage sludge and two agricultural residues.

The purpose of this study was to provide detailed knowledge of the morphological properties of ash particles, including the volumetric fractions and 3D distributions of phosphates that lay within them. The ash particles came from digested sewage sludge co-combusted with K- and Si-rich wheat straw or K-rich sunflower husks. X-ray micro-tomography were combined with elemental composition and crystalline phase information to analyse the ash particles in 3D.

Ash Transformation during Fixed-Bed Co-combustion of Sewage Sludge and Agricultural Residues with a Focus on Phosphorus.

This work investigates the ash transformation during fixed-bed co-combustion of sewage sludge mixtures with the agricultural residues wheat straw and sunflower husks, focusing on the fate of phosphorus (P) in the resulting ash fractions. The study aims to determine suitable process parameters for fixed-bed combustion of fuels previously investigated in single-pellet experiments. The pure fuels and fuel mixtures were combusted in a 20 kW residential pellet burner while monitoring the flue gas composition, temperature, and particulate matter formation.

Angular output of hollow, metal-lined, waveguide Raman sensors.

Hollow, metal-lined waveguides used as gas sensors based on spontaneous Raman scattering are capable of large angular collection. The collection of light from a large solid angle implies the collection of a large number of waveguide modes. An accurate estimation of the propagation losses for these modes is required to predict the total collected Raman power.

Conversion of a TEM10 beam into two nearly Gaussian beams.

To achieve high output power and/or high efficiencies, laser systems are often designed to operate with either high-order or multiorder transverse modes. This comes at the expense of beam quality. Herein, a technique for converting the two lobes of a higher-order (Hermite-Gaussian TEM(10)) beam into two TEM(00) beams is discussed.

Improved sensitivity gas detection by spontaneous Raman scattering.

Accurate, real-time measurement of the dilute constituents of a gaseous mixture poses a significant challenge usually relegated to mass spectrometry. Here, spontaneous Raman backscattering is used to detect low pressure molecular gases. Rapid detection of gases in the approximately 100 parts in 10(6) (ppm) range is described.

Enhanced spontaneous Raman scattering and gas composition analysis using a photonic crystal fiber.

Spontaneous gas-phase Raman scattering using a hollow-core photonic bandgap fiber (HC-PBF) for both the gas cell and the Stokes light collector is reported. It was predicted that the HC-PBF configuration would yield several hundred times signal enhancement in Stokes power over a traditional free-space configuration because of increased interaction lengths and large collection angles. Predictions were verified by using nitrogen Stokes signals.

Piezo-electric tunable fiber Bragg grating diode laser for chemical sensing using wavelength modulation spectroscopy.

This paper demonstrates, for the first time to our best knowledge, the application of a tunable external-cavity fiber Bragg grating diode laser in spectroscopic chemical sensing. A tunable fiber Bragg grating external-cavity semiconductor laser is demonstrated with over 10 nm of tuning range. A piezo-actuator was implemented to stretch the grating for rapid wavelength tuning of the laser.