http://hdl.handle.net/2282/145 Search the Channel search http://teora.hit.no/dspace/simple-search http://hdl.handle.net/2282/1340 Title: Acoustic chemometrics for material composition quantification in pneumatic conveying - The critical role of representative reference sampling <br/> <br/>Authors: Wagner, Claas; Ihunegbo, Felicia Nkem; Halstensen, Maths; Esbensen, Kim H. <br/> <br/>Abstract: Reliable monitoring of pneumatically conveyed particulate materials is critical for online detection and controlling material composition changes in the regimen of Process Analytical Technology (PAT), e.g. as the case investigated here: determination of varying concentration levels of extraneous material in a source stream. Results are reported from an experimental test campaign on a pilot-scale pneumatic conveying facility. Optimal sensor deployment and material flow rates are decisive parameters for signal quality and prediction performance. The test campaign resulted in an optimal sensor location/flow rate combination, based on which we present a validated prediction model (Partial Least Squares Regression model) for prediction of extraneous material concentration levels, with a RMSEP(rel) of 17.7% (RMSEP: 0.92) and r2 of 0.95. The present approach is based on acoustic chemometrics (a.c.). The impact of nominal reference values vs. representative reference values used as response variables in prediction models is discussed. Optimal reference values were obtained through the use of representative sampling equipment (based on Theory of Sampling, TOS), specifically designed for pneumatic conveying systems, and compared with nominal concentration levels, allowed an improvement of the prediction model: (RMSEP(rel), of 15% (RMSEP: 0.85) and r2 0.95). While the present experimental rig test resulted in relative minor quantitative improvements only, representative reference samples, required for prediction models, are essential when nominal concentration levels cannot be determined or are unknown, which is usually the case in enclosed pneumatic conveying systems, the target for this study. All prediction results are validated with independent data (test set validation) http://hdl.handle.net/2282/1339 Title: Acoustic chemometric prediction of total solids in bioslurry: A full-scale feasibility study for on-line biogas process monitoring <br/> <br/>Authors: Ihunegbo, Felicia Nkem; Madsen, Michael; Esbensen, Kim H.; Holm-Nielsen, Jens Bo; Halstensen, Maths <br/> <br/>Abstract: Dry matter is an important process control parameter in the bioconversion application field. Acoustic chemometrics, as a Process Analytical Technology (PAT) modality for quantitative characterisation of dry matter in complex bioslurry systems (biogas fermentation), has not been successful despite several earlier dedicated attempts. A full-scale feasibility study based on standard addition experiments involving natural plant biomass was conducted using multivariate calibration (Partial Least Squares Regression, PLS-R) of acoustic signatures against dry matter content (total solids, TS). Prediction performance of the optimised process implementation was evaluated using independent test set validation, with estimates of accuracy (slope of predicted vs. reference values) and precision (squared correlation coefficient, r2) of 0.94 and 0.97 respectively, with RMSEP of 0.32 % w/w (RMSEPrel = 3.86 %) in the range of 5.8 – 10.8 % w/w dry matter. Based on these excellent prediction performance measures, it is concluded that acoustic chemometrics has come of age as a full grown PAT approach for on-line monitoring of dry matter (TS) in complex bioslurry, with a promising application potential in other biomass processing industries as well. http://hdl.handle.net/2282/1338 Title: Confined granular flow in silos with inserts - Full-scale experiments <br/> <br/>Authors: Wójcik, M.; Tejchman, J.; Enstad, Gisle G. <br/> <br/>Abstract: The paper describes results of experimental investigations of confined granular flow in a silo with different inserts. Over 100 experiments were carried out with dry cohesionless sand in a large metal silo with and without inserts at Tel-Tek, dept. POSTEC, in Norway. Wall pressures and flow patterns were measured during both silo filling and emptying. Three different insert types were used in the silo: double cone, cone-in-cone and inverted cone. Different positions of inserts were also investigated. Experimental results with inserts were compared with those without inserts. Some design recommendations for silos equipped with inserts were worked out. http://hdl.handle.net/2282/1336 Title: Discrete LQ optimal control with integral action: A simple controller on incremental form for MIMO systems. <br/> <br/>Authors: Di Ruscio, David Luigi <br/> <br/>Abstract: A simple Linear Quadratic (LQ) optimal controller of velocity (incremental) form with approximately the same properties as a conventional PID controller of velocity form is presented, i.e. integral action. The proposed optimal controller is insensitive to slowly varying system and measurement trends and has the ability of stabilizing any linear dynamic system under weak assumptions such as the stabilizability of the system and the detectability of the system seen from the performance index.