Abstract: A method for operating a supercharged internal combustion engine. Before a cold start of the engine, an electric drive device of an electrically assisted exhaust-gas turbocharger of the engine is activated such that fresh air is compressed by a compressor of the turbocharger and, in the process, is heated and is conveyed via an open overrun air recirculation valve arranged downstream of the compressor, through a short circuit back to a suction side of the compressor of the turbocharger. A proportion of the air that is heated by way of the short-circuit operation of the compressor is, downstream of the compressor and upstream of a closed throttle flap of the engine, conducted via a secondary air system into an exhaust manifold and from there via a wastegate of the turbocharger into the catalytic converters of an exhaust-gas aftertreatment device of the engine.

Abstract: An air filter unit (1) for a carburetor (2) of a portable handheld work apparatus includes a filter element (3) and at least one clean air channel (10, 11) arranged between the filter element (3) and the carburetor (2). At least one condensation rib (29, 30, 31, 32) is arranged in the clean air channel (10, 11) running in flow direction.

Abstract: An air filter unit (1) for a carburetor (2) of a portable handheld work apparatus includes a filter element (3) and at least one clean air channel (10, 11) arranged between the filter element (3) and the carburetor (2). At least one condensation rib (29, 30, 31, 32) is arranged in the clean air channel (10, 11) running in flow direction.

Abstract: Fiber optic grating sensor demodulation systems are described that offer high speed and multiplexing options for both single and multiple parameter fiber optic grating sensors. To attain very high speeds for single parameter fiber grating sensors ratio techniques are used that allow a series of sensors to be placed in a single fiber while retaining high speed capability. These methods can be extended to multiparameter fiber grating sensors. Optimization of speeds can be obtained by minimizing the number of spectral peaks that must be processed and it is shown that two or three spectral peak measurements may in specific multiparameter applications offer comparable or better performance than processing four spectral peaks. Combining the ratio methods with minimization of peak measurements allows very high speed measurement of such important environmental effects as transverse strain and pressure.