Simulation and experiment of temperature uniformity of Erzhi Pills during hot air drying process / 中草药

Objective: To explore the law of temperature change in hot air drying process, and provide a theoretical basis for improving the drying efficiency and uniformity of Erzhi Pills (EP). Methods: Heat and mass transfer models were established to simulate the temperature distribution of the drying process of EP with no hole bottom and screen hole bottom based on COMSOL Multiphysics. The drying process of EP layer at 60, 80 and 100 ℃ was studied. The effective water diffusion coefficient (Deff) of EP layer was calculated by Fick’s second law plate model. A probe temperature sensor was used to monitor the temperature changes of the intermediate surface and interior of EP layer during the drying process to verify the drying model. Results: The surface and internal temperature of EP layer showed a trend of first sharp rise and then slow rise in the drying process of different hot air temperature. The inner temperature range of the drying model with no hole bottom and screen hole bottom was 55.3-56.0 ℃ and 57.5-57.7 ℃ respectively. The uniformity of drying temperature of EP can be improved by using drying plate with screen hole. The Deff range of the two model experiments were 0.76 × 10-7-2.82 × 10-7 m2/s and 1.15 × 10-7-3.94 × 10-7 m2/s, respectively. The experimental results showed that the model could well reflect the temperature variation of EP layer drying process within a certain drying temperature range. Conclusion: The change of drying temperature was directly reflected through the reliable hot air drying model of EP layer. The study provides reference for the optimization of EP drying process.

The Three-dimensional Finite-Element Simulation of Alternating Electromagnetic Fields for Microcirculation Experiments / 中国医学物理学杂志

Objective: In order to understand temporal and spatial distributions of alternating electromagnetic field (AEMF) of a coil thoroughly, the 3-D finite-element models of this kind of Biomagnetic Fields are established and analyzed for the research on bioeffect of magnetic field on microcirculation. Methods: Designing CAD models, setting boundary conditions, meshing models and obtaining numerical solutions were completed all within Comsol Multiphysics in terms of the theory of electromagnetic field. Results: Axial and radial plot of spatial attenuation rate of the AEMF, which were accordance with measured data, were simulated while the temporal and spatial distributions of AEMF were acquired. Conclusion: Models of 3-D finite-element of this kind of biomagnetic fields which appeared to exactly simulate the real magnetic field were first established systematically, and solved the placing problem of magnetic fields for the research on bioeffect of magnetic field on microcirculation and provided platforms for the simulation of hemodynamic of blood flow in the magnetic field.