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- Grahn, Markus, 1978, et al.
(författare)
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A Structure and Calibration Method for Data-Driven Modeling of NOX and Soot Emissions from a Diesel Engine
- 2012
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627.
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Tidskriftsartikel (refereegranskat)abstract
- The development and implementation of a new structure for data-driven models for NOX and soot emissions is described. The model structure is a linear regression model, where physically relevant input signals are used as regressors, and all the regression parameters are defined as grid-maps in the engine speed/injected fuel domain. The method of using grid-maps in the engine speed/injected fuel domain for all the regression parameters enables the models to be valid for changes in physical parameters that affect the emissions, without having to include these parameters as input signals to the models. This is possible for parameters that are dependent only on the engine speed and the amount of injected fuel. This means that models can handle changes for different parameters in the complete working range of the engine, without having to include all signals that actually effect the emissions into the models. The approach possibly also enables for the model to handle the main differences between steady-state engine operation and transient engine operation, thus possibly being able to use steady-state engine measurement data to calibrate the model, but still achieve acceptable performance for transient engine operation. This, however, is not evaluated in this study. The model structure has been used to create models for NOX and soot emissions. These models have been calibrated using measured steady-data from a 5 cylinder Volvo passenger car diesel engine with a displacement volume of 2.4 liters, equipped with a turbocharger, an exhaust gas recirculation system, and a common rail injection system. The models estimate NOX mass flow with a root mean square error of 0.0021 g/s and soot mass flow with a root mean square error of 0.59 mg/s for the steady-state engine data used in this study. The models are capable of reacting to different calibratable engine parameters, and they are also fast to execute. This makes them suitable for development of engine management system optimization. The models could also be implemented directly into an engine management system. For comparison, three other fast models of different types for NOX and soot emissions have been implemented and evaluated.
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| 2. |
- Grahn, Markus, 1978, et al.
(författare)
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B-splines for Diesel Engine Emission Modeling
- 2012
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Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - 2405-8963. - 9783902823168 ; , s. 416-423
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Konferensbidrag (refereegranskat)abstract
- The equivalence between linear interpolation and B-spline functions of degree 1 is described. The equivalence is used to express interpolation based diesel engine NOX and soot emission models as B-spline functions, and to apply data fitting methods for B-spline functions to perform calibration of the models. This strategy leads to that the model calibration can be calculated directly by means of analytically solving a minimization problem. The B-spline representation also makes it possible to control the smoothness and extrapolation behavior of the interpolation maps in the models in a controlled manner. The models have been calibrated using measured steady-state data from a 5-cylinder Volvo passenger car diesel engine with a displacement volume of 2.4 liters, equipped with a turbocharger, an exhaust gas recirculation system, and a common rail injection system. The calibrated model for NOX emissions predicts the NOX mass ow with a root mean square error of 1.6 mg/s, and the calibrated model for soot emissions predicts the soot mass ow with a root mean square error of 0.65 mg/s. The described equivalence between linear interpolation and B-spline functions of degree 1 could also be used for calibration of other models of similar structure.
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| 3. |
- Johansson, Markus, 1978, et al.
(författare)
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Source Modeling using Phaseless Low-Frequency Near-Field Measurements
- 2012
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Ingår i: IEEE Transactions on Electromagnetic Compatibility. - 0018-9375 .- 1558-187X. ; 54:3, s. 613-624
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Tidskriftsartikel (refereegranskat)abstract
- Field measurements of both amplitude and phase generally are more complicated and require more expensive equipment than amplitude-only measurements. Phase retrieval from measured phaseless field data is, therefore, of interest for source modeling in dosimetry applications, electromagnetic compatibility investigations, near-field to far-field transformations and antenna diagnostics. We here present a phase-retrieval method that uses an optimization algorithm based on the phase angle gradients of a functional. Numerical test cases have shown that the method is working for different initial phase distributions as well as different placements of the source. The method also works well for a test case with measured 50 Hz magnetic flux density from a transformer. The obtained phase angles on a measurement plane in front of the transformer gave calculated field amplitudes on other measurement planes that agree well with measured field. The ratios between the largest amplitude difference and the largest measured amplitude for the three Cartesian magnetic flux density components, for one of the planes, are for example 6.62%, 9.51% and 6.40%.
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