Browsing by Subject "Design of experiments"

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Guest editors’ introduction to the special issue on “Recent advances in design and analysis of experiments and observational studies in agriculture”
(2020) Piepho, Hans-Peter; Tempelman, Robert J.; Williams, Emlyn R.
The Journal of Agricultural, Biological and Environment Statistics (JABES) special issue on Recent Advances in Design and Analysis of Experiments and Observational Studies in Agriculture covers a select set of topics currently of primary importance in the field. Efficient use of resources in agricultural research, as well as valid statistical inference, requires good designs, and this special issue boasts seven papers providing both review and cutting-edge methodology for the purpose. A broad range of methods for analysis of data arising in different branches agricultural research is covered in another five exciting papers. This special issue highlights the importance of and opportunities for applied statistics in agriculture.
On the structural analysis and optimal input design for joint state and parameter estimation
(2025) Lepsien, Arthur; Kügler, Philipp; Schaum, Alexander
This paper addresses the problem of joint state and parameter estimation for nonlinear affine-input systems with positive parameters including the design of a closed-loop optimal input adaptation to increase an identifiability measure for the system. The identifiability itself is considered in the context of structural observability of the system dynamics based on structural analysis of the system including the unknown parameters as additional states. In particular, the network graph-based interpretation of structural observability is employed at this point. This analysis motivates to include time derivatives of the measurements as additional system outputs to enhance the structural observability properties. For this purpose robust exact differentiation is considered, relying on the super-twisting algorithm to obtain finite time convergent estimates of these signals. Using the extended measurement signal, a continuous-discrete Extended Kalman filter is proposed that ensures strictly positive estimates for the parameters. Based on the estimates of states and parameters the input signal is determined using a moving horizon optimal predictive control that evaluates the condition number of the Fisher information matrix, thus maximizing the information content of the measurements with respect to the parameters. The proposed scheme extends and combines different previously discussed approaches from the literature and is evaluated by means of a thermal process example in simulation and experiment, showing high potential for similar system identification problems.
Upscaling of alkaline pea protein extraction from dry milled and pre-treated peas from laboratory to pilot scale: Optimization of process parameters for higher protein yields
(2022) Schmidt, Florian; Blankart, Max; Wanger, Janina; Scharfe, Markus; Scheuerer, Theresa; Hinrichs, Jörg
The upscaling of pea protein extraction from laboratory scale with a centrifuge to pilot scale with a decanter centrifuge was investigated, and the pea protein extraction efficiency from dry milled and pre-treated peas was compared. Upscaling from laboratory to pilot scale is possible since starch was under the limit of detection (< 0.5%). The protein banding pattern of a sodium-dodecyl-sulfate polyacrylamide gel electrophoresis confirmed that albumins and globulins were extracted by alkali extraction. Protein yield increased from 59.5% to 67.1% for dry milled peas due to constant and quick discharge of dry matter in the decanter centrifuge. For pre-treated peas, the protein yield increased from 60.3% to 94.3%, which is explained by an improved cutting and improved separation in pilot scale compared to laboratory scale. The impact of acceleration, mass flow, differential speed and their respective interactions in the decanting process was determined with a design of experiments. For dry milled peas, only the mass flow exceeded the significance level. However, a mass flow of 5 kg h −1 , an acceleration of 1000 g ×and a differential speed of 50 min −1 led to the highest protein yield of 75.6%. The obtained protein yields for the pre-treated peas were in the range of 83 to 96% and therefore did not show significant differences in protein yield.