Numerical Process Optimization Research Articles

Synergistic Effect of Advanced Refractance Window Drying on Quality Characteristics of Potato Slices and Numerical Process Optimization

Synergistic Effect of Advanced Refractance Window Drying on Quality Characteristics of Potato Slices and Numerical Process Optimization

A Comparative Study on the Debittering of Kinnow (Citrus reticulate L.) Peels: Microbial, Chemical, and Ultrasound-Assisted Microbial Treatment

Kinnow mandarin (Citrus reticulate L.) peels are a storehouse of well-known bioactive compounds, viz., polyphenols, flavonoids, carotenoids, limonoids, and tocopherol, which exhibit an effective antioxidant capacity. However, naringin is the most predominant bitter flavanone compound found in Kinnow peels that causes their bitterness. It prohibits the effective utilization of peels in food-based products. In the present study, a novel approach for the debittering of Kinnow peels has been established to tackle this problem. A comparative evaluation of the different debittering methods (chemical, microbial, and ultrasound-assisted microbial treatments) used on Kinnow peel naringin and bioactive compounds was conducted. Among the chemical and microbial method; solid-state fermentation with A. niger led to greater extraction of naringin content (7.08 mg/g) from kinnow peels. Moreover, the numerical process optimization of ultrasound-assisted microbial debittering was performed by the Box–Behnken design (BBD) of a response surface methodology to maximize naringin hydrolysis. Among all three debittering methods, ultrasound-assisted microbial debittering led to a greater hydrolysis of naringin content and reduced processing time. The optimum conditions were ultrasound temperature (40 °C), time (30 min), and A. niger koji extract (1.45%) for the maximum extraction rate of naringin (11.91 mg/g). These debittered Kinnow peels can be utilized as raw material to develop therapeutic food products having a high phytochemical composition without any off-flavors or bitterness.

Determination of Material and Failure Characteristics for High-Speed Forming via High-Speed Testing and Inverse Numerical Simulation

In conventional forming processes, quasi-static conditions are a good approximation and numerical process optimization is the state of the art in industrial practice. Nevertheless, there is still a substantial need for research in the field of identification of material parameters. In production technologies with high forming velocities, it is no longer acceptable to neglect the dependency of the hardening on the forming speed. Therefore, a method for determining material characteristics in processes with high forming speeds was developed by designing and implementing a test setup and an inverse parameter identification. Two acceleration concepts were realized: a pneumatically driven one and an electromagnetically driven one. The method was verified for a mild steel and an aluminum alloy proving that the identified material parameters allow numerical modeling of high-speed processes with good accuracy. The determined material parameters for steel show significant differences for different stress states. For specimen geometries with predominantly uniaxial tensile strain at forming speeds in the order of 104–105/s the determined yield stress was nearly twice as high compared to shear samples; an effect which does not occur under quasi-static loading. This trend suggests a triaxiality-dependent rate dependence, which might be attributed to shear band induced strain localization and adiabatic heating.

Curing kinetics study of epoxy resin/hyperbranched poly(amideamine)s system by non-isothermal and isothermal DSC

AbstractCuring kinetics of epoxy resin/hyperbranched poly(amide amine)s (HPAMAM) system was studied by non-isothermal and isothermal differential scanning calorimetry (DSC). Non-isothermal DSC scans indicated that H-PAMAM was an effective curing agent of epoxy resin. The apparent activation energy (E) was 54.3 kJ/mol calculated through Kissinger method, and the kinetic parameters were determined by Málek method for the kinetic analysis of the thermal treatment obtained by DSC measurement. A two-parameter (m, n) autocatalytic model (Sěsták-Berggren equation) was found to be the most adequate selected kinetic model. In addition, the predicted curves from the kinetic model fit well with the nonisothermal DSC thermogram. The isothermal DSC method was used to investigate the curing process for resin at 60, 65, 70, 75 and 80 °С, respectively. Isothermal kinetic parameters, including k1, k2, m and n, were determined based on an autocatalytic mechanism proposed by Kamal. Both models were validated for a fitting to the experimental data by the Levenberg-Marquardt method. A process to determine the initial values for the fitting procedure was also proposed. The predictions of the validated models were in good agreement with the measured data, and were therefore applicable for numerical process optimization

Improving the batch-to-batch reproducibility in microbial cultures during recombinant protein production by guiding the process along a predefined total biomass profile

In industry Escherichia coli is the preferred host system for the heterologous biosynthesis of therapeutic proteins that do not need posttranslational modifications. In this report, the development of a robust high-cell-density fed-batch procedure for the efficient production of a therapeutic hormone is described. The strategy is to guide the process along a predefined profile of the total biomass that was derived from a given specific growth rate profile. This profile might have been built upon experience or derived from numerical process optimization. A surprisingly simple adaptive procedure correcting for deviations from the desired path was developed. In this way the batch-to-batch reproducibility can be drastically improved as compared to the process control strategies typically applied in industry. This applies not only to the biomass but, as the results clearly show, to the product titer also.

A new kinetic and viscosity model for liquid composite molding simulations in an industrial environment

AbstractLiquid composite molding is broadly used for manufacturing composite parts. Apart from the preforming of the dry fibrous material, mold filling and curing of the resin are the main steps in the manufacturing process. For process simulation numerical methods, like finite element methods are applied. Flow models describing the flow behavior through a porous medium are well established. The ability to predict and monitor the curing process in liquid composite molding is crucial for manufacturing process optimization in case of application of rapid curing resin systems. Based on differential scanning calorimetry and rheological experiments, cure kinetics and viscosity of a resin system were characterized. A new kinetic and complex viscosity model is proposed to predict epoxy resin properties in numerical modeling of liquid composite molding. The semi‐empirical models are simple to use and therefore suitable for process optimization in an industrial environment. Both models were validated by a fitting to the experimental data by the Levenberg‐Marquardt method. A process to determine the initial values for the fitting procedure is also proposed. The predictions of the validated models were in good agreement with the measured data, and are therefore applicable for numerical process optimization. Polym. Compos. 25:255–269, 2004. © 2004 Society of Plastics Engineers.