Heat and Mass Transport during Microwave Heating of Mashed Potato in Domestic Oven—Model Development,Validation, and Sensitivity Analysis

A 3‐dimensional finite‐element model coupling electromagnetics and heat and mass transfer was developed to understand the interactions between the microwaves and fresh mashed potato in a 500 mL tray. The model was validated by performing heating of mashed potato from 25 °C on a rotating turntable in a microwave oven, rated at 1200 W, for 3 min. The simulated spatial temperature profiles on the top and bottom layer of the mashed potato showed similar hot and cold spots when compared to the thermal images acquired by an infrared camera. Transient temperature profiles at 6 locations collected by fiber‐optic sensors showed good agreement with predicted results, with the root mean square error ranging from 1.6 to 11.7 °C. The predicted total moisture loss matched well with the observed result. Several input parameters, such as the evaporation rate constant, the intrinsic permeability of water and gas, and the diffusion coefficient of water and gas, are not readily available for mashed potato, and they cannot be easily measured experimentally. Reported values for raw potato were used as baseline values. A sensitivity analysis of these input parameters on the temperature profiles and the total moisture loss was evaluated by changing the baseline values to their 10% and 1000%. The sensitivity analysis showed that the gas diffusion coefficient, intrinsic water permeability, and the evaporation rate constant greatly influenced the predicted temperature and total moisture loss, while the intrinsic gas permeability and the water diffusion coefficient had little influence.     

Multiphysics Modeling of Microwave Heating of a Frozen Heterogeneous Meal Rotating on a Turntable

A 3‐dimensional (3‐D) multiphysics model was developed to understand the microwave heating process of a real heterogeneous food, multilayered frozen lasagna. Near‐perfect 3‐D geometries of food package and microwave oven were used. A multiphase porous media model combining the electromagnetic heat source with heat and mass transfer, and incorporating phase change of melting and evaporation was included in finite element model. Discrete rotation of food on the turntable was incorporated. The model simulated for 6 min of microwave cooking of a 450 g frozen lasagna kept at the center of the rotating turntable in a 1200 W domestic oven. Temperature‐dependent dielectric and thermal properties of lasagna ingredients were measured and provided as inputs to the model. Simulated temperature profiles were compared with experimental temperature profiles obtained using a thermal imaging camera and fiber‐optic sensors. The total moisture loss in lasagna was predicted and compared with the experimental moisture loss during cooking. The simulated spatial temperature patterns predicted at the top layer was in good agreement with the corresponding patterns observed in thermal images. Predicted point temperature profiles at 6 different locations within the meal were compared with experimental temperature profiles and root mean square error (RMSE) values ranged from 6.6 to 20.0 °C. The predicted total moisture loss matched well with an RMSE value of 0.54 g. Different layers of food components showed considerably different heating performance. Food product developers can use this model for designing food products by understanding the effect of thickness and order of each layer, and material properties of each layer, and packaging shape on cooking performance.     

Temporal redundancy methods using risk-sensitive filtering andparameter estimation to detect failures in neutronic sensors duringreactor start-up and steady-state operation

In this paper, simple linear single-input-single output models of the reactor-regulating system have been considered, and risk-sensitive filtering and risk-sensitive parameter-estimation techniques have been used to obtain temporal-redundancy relations. While a risk-sensitive filter is used to provide a temporally redundant measurement of reactivity from an analytically redundant process parameter during a reactor start-up, a risk-sensitive parameter estimation technique is used to obtain temporally redundant measurements during steady state operation     

Synthesis and structural studies on Ni0.5+x Zn0.5Cu x Fe2−2x O4

The mixed ferrites of Ni–Zn–Cu are synthesized using ceramic double sintering technique. Cu and Ni are substituted in steps of x=0.1 at the interstitial sites of Fe. Powders of mixed ferrites of Ni–Zn–Cu are studied using XRD. The mixed ferrites show a single phase and face center cubic structure for all concentrations. The substitution of Cu and Ni are confirmed from the variation of lattice constant. The cation distribution in the A and B sites of the ferrites is estimated. Mixed ferrites of Ni–Zn–Cu are characterized using a.c. conductivity and magnetic susceptibility methods. The variation of activation energy, magnetic moment and Curie temperature with concentration of Fe ions explains the alterations of the energy levels of d bands. Hopping of charge carriers and the presence of different ionic states of Ni, Cu, and Fe ions are discussed using the FTIR and EPR spectra.     

Experimental and Numerical Investigation of the Deformation and Fracture Mode of Microcantilever Beams Made of Cr(Re)/Al2O3 Metal–Matrix Composite

Metallurgical and Materials Transactions A - This work presents a combined experimental and computational study of the deformation and fracture of microcantilever specimens made of...     

Spectroscopic Investigations of Physicochemical Interactions on Mild Steel in an Acidic Medium by Environmentally Friendly Green Inhibitors

The influences of Polycarpaea corymbosa (PC) and Desmodium triflorum (DT) leaf extracts on the corrosion behavior of mild steel (MS) in 1.0 M HCl was investigated by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The effect of temperature on the corrosion behavior of MS in 1.0 M HCl with the addition of plant extracts was studied in the temperature range of 300 K–320 ± 1 K. The results revealed that PC and DT were excellent green inhibitors and the inhibition efficiencies obtained from weight loss and electrochemical experiments were in good agreement. Inhibition efficiencies up to 91.78 % for PC and 92.99 % for DT were obtained. Potentiodynamic polarization studies revealed that both the inhibitors behaved as mixed‐type inhibitors. Adsorption behavior of these green inhibitors on the MS surface was found to obey the Langmuir adsorption isotherm. The thermodynamic parameter values of free energy of adsorption (?G_ads) and enthalpy of adsorption (?H_ads) revealed that each inhibitor was adsorbed on the MS surface via both chemisorption and physisorption mechanisms. The adsorption mechanism of inhibition was supported by FT–IR, UV–Visible, WAXD and SEM–EDS.     

Ferrocene‐Incorporated Cobalt Sulfide Nanoarchitecture for Superior Oxygen Evolution Reaction

Here, ferrocene(Fc)‐incorporated cobalt sulfide (Co_xS_y) nanostructures directly grown on carbon nanotube (CNT) or carbon fiber (CF) networks for electrochemical oxygen evolution reaction (OER) using a facile one‐step solvothermal method are reported. The strong synergistic interaction between Fc‐Co_xS_y nanostructures and electrically conductive CNTs results in the superior electrocatalytic activity with a very small overpotential of ≈304 mV at 10 mA cm^?2 and a low Tafel slope of 54.2 mV dec^?1 in 1 m KOH electrolyte. Furthermore, the Fc‐incorporated Co_xS_y (FCoS) nanostructures are directly grown on the acid pretreated carbon fiber (ACF), and the resulting fabricated electrode delivers excellent OER performance with a low overpotential of ≈315 mV at 10 mA cm^?2. Such superior OER catalytic activity can be attributed to 3D Fc‐Co_xS_y nanoarchitectures that consist of a high concentration of vertical nanosheets with uniform distribution of nanoparticles that afford a large number of active surface areas and edge sites. Besides, the tight contact interface between ACF substrate and Fc‐Co_xS_y nanostructures could effectively facilitate the electron transfer rate in the OER. This study provides valuable insights for the rational design of energy storage and conversion materials by the incorporation of other transition metal into metal sulfide/oxide nanostructures utilizing metallocene.