Optimization of stir-baked technology for Flos Sophorae Immaturus tea according to quadratic regression rotation-orthogonal design method and quality evaluation

This study aimed to optimize the stir-baked technology for Flos Sophorae Immaturus tea (FSIT) and evaluate the quality of FSIT. The optimum stir-baked conditions were found to be as follows: amount, 3.9 kg; rotation speed, 400 r/min; and time required to reach the temperature of 120°C, 5 min and maintained for 3.9 min after adding 15 mL of 1% stevioside. The machine-made FSIT soup was clear and golden in color, with charred taste, no bitterness, no peculiar smell, and improved sensory quality under the above-mentioned conditions. Heavy metal contents and microorganisms did not exceed the national standards.

Modal characteristics of harmonic gear transmission flexspline based on orthogonal design method

The flexspline features several modal characteristics that are related to its structural parameters, which could impose an impact on the stability and reliability of the system of harmonic gear transmission. In this article, we have integrated the method of orthogonal design with the approach of finite element, so as to study the modal characteristics of flexspline under varying structural parameters. Furthermore, we have analyzed the ways of how varying structural parameters could impose an impact on the first eight-order natural frequencies of flexspline. In addition, by adopting the method of range and variance analysis for the obtained data, we have examined the influence imposed by varying structural parameters on the modal characteristics of flexspline, which could lay a foundation for the optimal design of the structural parameters of flexspline.

Inlet Box Structure Optimization of a Large Axial-Flow Fan Using Response Surface Methodology

Large axial-flow fans are widely used in many fields. The inlet box is an integral part of large axial-flow fans, and a well-designed inlet box could effectively improve fan efficiency. However, the inlet box structure is complicated, and the existing inlet box design method severely depends on the design experience. In this study, we propose a structure optimization design system based on a surrogate model technique for researching the critical structure parameters of the inlet box and accomplishing aerodynamic performance optimization. As for this expensive optimization problem, the design system contains twice optimization procedures by using the Response Surface Methodology (RSM) with the orthogonal design method. The optimization object is an existing large axial-flow fan. The optimization objective is the total pressure efficiency of the fan, and the total pressure rise is the restriction condition. We generate eighteen different inlet boxes connect with the same impeller and outlet pipe by the orthogonal design method and calculated fan aerodynamic performance by CFX software. After the first optimization, we find the key structural parameters by the sensitivity analysis and the reselect variables total of 25 cases are adopted in a further RSM optimal process. The ultimate surrogate model estimates the fan with the optimal inlet box has a better aerodynamic characteristic and a 6.7% total pressure efficiency rise. Finally, we compare the aerodynamic characteristics of the ultimate design fan and the initial fan by CFD simulation. The numerical results show that: the total pressure efficiency is 6.5% higher than that of the initial impeller, and the pressure rise is 3% higher than that of the initial impeller. The result demonstrates that some most critical parameters of the inlet box structure decide the aerodynamic performance, and the inlet box optimization effectively increases the fan efficiency in the meanwhile.

Surface Roughness Prediction Model for Machining O1 Die Steel Through EDM

The objective of this paper is to generate a mathematical model in order to minimize the value of surface roughness (Ra) through EDM by constructing an objective function consisting of combination of process parameters. Taguchi orthogonal design method of experiments with three process parameters viz., current, pulse-on-rate, pulse-off-rate were used to generate 25 numbers of experiments L25 at five levels. Experiments were carried out in Electronica S50 (CNC) EDM. Data obtained for performance measurement was subjected regression analysis using ANOVA. Equation was obtained for the surface roughness as a function of current, pulse-on rate, pulse-off-rate.It is found that discharge current, pulse-on-rate, and pulse-off-rate have significant effect on the Ra. Higher values of current and pulse-on-rate increased surface roughness. Lower current, lower pulse-on-rate and relatively higher pulse-off-rate produced a better surface finish.

Numerical Analysis of the Effect of an Inner Structure of a Cubic Frame Reef on Flow Field

Artificial reefs have been deposited along the coastline of China for over 30 years. The purpose of artificial reef construction is to form a changeable and complicated flow field that can promote the water exchange of different layers and attract more fish and marine organisms, and the structure of artificial reefs plays a decisive role in these processes. However, the research on the hydrodynamic character of artificial reefs has primarily focused on improving their size or shape. The guide plate has a significant effect on the flow field effect of the cubic reef, which has been confirmed in previous studies. In this article, guide plates were extended to the interior of the cubic reef and finally form an inner structure consisting of four isosceles triangles and right triangles. The flow field effect of the inner structure is numerically simulated by the orthogonal design method. Results indicate that the inner structure creates a significant disturbance on the flow field. A crossed design of hole diameters on plates contributes to the formation of upwelling and extension of the wake region. The flux of upwelling in the different planes indicates that the flow of upwelling is strong above the upwelling reef and has a remarkable effect. This study provides a scientific reference for the structural design of artificial reefs.

Kinetic study of carbon monoxide methanation over mesoporous Ni-Mo catalyst prepared by a hydrothermal method

The kinetics of carbon monoxide methanation over Ni-Mo-SiO2 catalyst were studied. The model was developed based on catalyst tests carried out in a fixed-bed reactor at a reaction temperature varied from 300 °C to 450 °C under a pressure from 0.1 to 1.5 MPa with a weight hourly space velocity of 60,000 mL h−1 g−1. An orthogonal design method was adopted to select test points with temperature, pressure, and feed compositions as factors. Based on the experimental observations, a Langmuir–Hinshelwood equation kinetic model was formulated and its parameters were estimated by fitting the experimental data implemented in MATLAB. The activation energy for the formation of CH4 was 45.4 kJ mol−1 and comparing the experimental and model-predicted data showed that the proposed model gives a reasonable fit with an average absolute relative deviation of ±9.8%.