In this study, we aimed to describe a modern, efficient, and reproducible methodology to optimize respiration rate parameters coupled with transport properties in mass balances describing Modified atmosphere packaging...
详细信息
In this study, we aimed to describe a modern, efficient, and reproducible methodology to optimize respiration rate parameters coupled with transport properties in mass balances describing Modified atmosphere packaging (MAP) systems. We considered mass balances for three different respiration rate j film (exponential, competitive and uncompetitive Michaelis-Menten kinetics) coupled with transport properties for two different packaging films. Experiments were conducted to validate the methodology using grapes placed in a polypropylene container opened on the top and sealed with packaging films. The methodology relies on a numerical optimization procedure called the trust-region-reflective algorithm. We determined the predictive capability of models using goodness-of-fit criteria and assessed parameter uncertainty through standard errors. We also calculated the first-order optimality measure and the relative change in the sum of squares to verify the convergence of the implemented algorithm. Results showed that the respiration rate parameters obtained with this methodology for the exponential model provided a better fit than for the other two models. The fitting for the kinetic models is not very suitable since we found that the normalized standard errors were rather high. In conclusion, the methodology is robust, and we expect that it serves as a tool for assessing MAP technology design.
A bottom-up material modeling based on a nonlocal crystal plasticity model requires information of a large set of physical and phenomenological parameters. Because of the many material parameters, it is inherently dif...
详细信息
A bottom-up material modeling based on a nonlocal crystal plasticity model requires information of a large set of physical and phenomenological parameters. Because of the many material parameters, it is inherently difficult to determine the nonlocal crystal plasticity parameters. Therefore, a robust method is proposed to parameterize the nonlocal crystal plasticity model of a body-centered cubic (BCC) material by combining a nanoindentation test and inverse analysis. Nanoindentation tests returned the load-displacement curve and surface imprint of the considered sample. The inverse analysis is developed based on trust-region-reflective algorithm, which is the most robust optimization algorithm for the considered non-convex problem. The discrepancy function is defined to minimize both the load-displacement curves and the surface topologies of the considered material under applying varied indentation forces obtained from numerical models and experimental output. The numerical model results based on the identified material properties show good agreement with the experimental output. Finally, a sensitivity analysis performed changing the nonlocal crystal plasticity parameters in a predefined range emphasized that the geometrical factor has the most significant influence on the load-displacement curve and surface imprint parameters.
In this study, the authors introduce a new and systematic procedure for the design and optimisation of a conductor-backed coplanar waveguide low-pass filter (LPF). The width of the centre conductor (i.e. signal trace)...
详细信息
In this study, the authors introduce a new and systematic procedure for the design and optimisation of a conductor-backed coplanar waveguide low-pass filter (LPF). The width of the centre conductor (i.e. signal trace) is modelled in a truncated Fourier series, whereas the gap to the adjacent grounds is maintained constant relative to the width variation. Transmission lines theory is adopted to model the LPF and establish an optimisation setup. Three optimisation techniques;namely, trust-region-reflective algorithm, symbiotic organism search, and genetic algorithm are investigated to minimise the developed bound-constrained non-linear objective function. To verify the proposed procedure, an LPF with a cutoff frequency of 2 GHz is optimised, simulated, and measured. The transmission parameter in the passband is found to be in the range -0.3 +/- 0.1 dB, and better than -30 dB in the stopband.
In this paper, we consider a two-dimensional inverse medium problem from noisy observation data. We propose effective reconstruction algorithms to detect the number, the location and the size of the piecewise constant...
详细信息
In this paper, we consider a two-dimensional inverse medium problem from noisy observation data. We propose effective reconstruction algorithms to detect the number, the location and the size of the piecewise constant medium within a body, and then we try to recover the unknown shape of inhomogeneous media. This problem is nonlinear and ill-posed, thus we should consider stable and elegant approaches in order to improve the corresponding approximation. We give several examples to show the viability of our proposed algorithms.
This paper proposes a new impedance-based technique to locate all fault types in distribution networks with/without distributed generators. A new procedure to form an impedance matrix using only series impedances of t...
详细信息
This paper proposes a new impedance-based technique to locate all fault types in distribution networks with/without distributed generators. A new procedure to form an impedance matrix using only series impedances of the distribution lines is introduced. The impedance matrix along with the prefault and during-fault voltage phasors at few buses is used to estimate the injection fault current via the least-squares technique. Linear least-squares estimator is utilized if microphasor measurement units (mu PMUs) are installed along the network. However, a nonlinear least-squares problem solved by the trust-region-reflective algorithm is used when only the voltage magnitudes are provided by smart meters. The operation of the standard protective devices in the distribution networks is used to reduce the computational burden of the proposed method. Also, a generalized measurement placement algorithm is studied using the discovered features of the impedance matrix. In addition, the Sobol's sensitivity analysis is conducted to quantify the importance of different input factors on the fault location accuracy. The effectiveness of the proposed method is validated on a real 134-bus, 13.8 kV distribution network under several fault scenarios and noisy measurements.
In this paper, we consider the recovery of photon diffusion coefficient in the case of piecewise constant coefficients in optical tomography from boundary measurements of light propagation within a tissue. We propose ...
详细信息
In this paper, we consider the recovery of photon diffusion coefficient in the case of piecewise constant coefficients in optical tomography from boundary measurements of light propagation within a tissue. We propose an effective reconstruction algorithm to detect the number, the location, the size and the shape of piecewise constant coefficients. This problem is nonlinear and severely ill-posed, thus we should consider a regularisation technique in our approach in order to improve the corresponding approximation. We give several examples to show the viability of our proposed method.
暂无评论