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A compact frequency-modulated, continuous wave (FM-cw) lidar system for measurement of distributed aerosol plumes and hard targets is presented. The system is based on intensity modulation of a laser diode and quadrature detection of the return signals. The advantages of using laser diode amplitude modulation and quadrature detection is a large reduction in the hardware required for processing and storing return signals as well as the availability of off-the-shelf integrated electronic components from the wireless and telecommunication communities. Equations to invert the quadrature signal components and determine spatial distributions of multiple targets are derived. Spatial scattering intensities are used to extract aerosol backscatter coefficients, which can then be directly compared to microphysics aerosol models for environmental measurements. Finally, results from laboratory measurements with a monostatic FM-cw lidar system with both hard targets and aerosols are discussed.

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The emissions profile from a natural gas (NG) stationary power, stoichiometric, engine have been measured. Of particular interest are the unregulated emissions (especially formaldehyde) from this engine class. A relatively small 250 kW Caterpillar G3406 engine without a catalyst was used as the test platform with the emissions being characterized as a function of applied load and external conditions. In addition, multiple formaldehyde measurement techniques have been used and are compared. This paper presents the formaldehyde results, comparison of formaldehyde with various other parameters, a comparison of the different measurement techniques, and measurement of other toxic emissions from this engine.