Orthogonal Test Method Research Articles

Heat-fluid-solid coupling heat transfer analysis and parameter optimization in walnut drying device based on finite element method

The moisture content of freshly picked walnuts is very high. In order to facilitate storage and transportation, it needs to be dried to prevent mildew. In this study, the pre-drying simulation and experimental study were carried out on the walnut drying equipment made by the research group to determine the optimal drying parameters. The effects of different inlet temperatures (353K, 373K, 393K), drying wind speeds (1.1 m/s, 1.4 m/s, 1.7 m/s) and drying time (30min, 45min, 60min) on the temperature and velocity fields of fluid and walnuts in the drying device were investigated by using the orthogonal test method of three factors and three levels. FLUENT software was used to simulate the drying process of open walnuts under hot air heating, and the distribution of fluid temperature field and velocity field in the drying device and the temperature change law of walnuts were obtained. The results show that when the inlet temperature is 393K, the inlet velocity is 1.7 m/s, and the drying time is 45min, the temperature field distribution of fluid and walnut in the drying device is the best and the change is the most uniform. In addition, the temperature change of the simulation results is consistent with the test results through experiments, which verifies the reliability of the simulation results. In order to more accurately simulate the change law of temperature and humidity transfer in hot air drying of walnuts, the walnut was modeled as a sphere consisting of three layers: walnut shell, air gap and walnut kernel. The reliability of the parameters was verified by surface response analysis. Taking inlet temperature, velocity and drying time as influencing factors and temperature change rate as evaluation index, the determination coefficient of regression model was R2 = 0.9966, and the correction determination coefficient Adj. R2 = 0.9922, indicating three influences. This study provides a theoretical basis for determining the optimum operating parameters of open walnut pre-drying, and has application value for walnut food processing.

Orthogonal Experimental Study on the Ratio of Similar Materials of Coal Body

According to the coal samples collected from Zhaogu No.2 Coal Mine as raw coal samples, the similar materials of coal body were studied by using river sand, pulverized coal, Portland cement and calcium carbonate. The orthogonal test method of four factors (bone glue ratio, aggregate ratio, rubber ratio, water mixing rate) and three levels was used to obtain the physical and mechanical parameters such as density, uniaxial compressive strength, elastic modulus, cohesion, internal friction angle and tensile strength of coal similar materials. The range analysis method was used to obtain the key influencing factors and variation rules of the physical and mechanical properties of coal similar materials. Finally, the method of multiple linear regression analysis was used to obtain the similar material ratio that was most consistent with the mechanical properties index of raw coal. The ratio of calcium carbonate: cement: river sand: coal powder: water = 1: 5: 0.9: 5.9: 3.2. The density error, compressive strength error, elastic modulus error and cohesion error of coal sample and raw coal are small, which proves that the similar material is similar to the mechanical properties of raw coal, and provides guidance for subsequent research.

Design and Experiment of Active Spiral Pushing Straw Row-Sorting Device

Aiming to solve the problems of excessive straw residue and large soil loss in the seeding belt of the straw row-sorting operation when the full volume of straw is crushed and returned to the field in the northeastern region of China, an active spiral pushing straw row-sorting device (ASPSRD) was designed in this paper. The straw on the surface of the land is collected and stirred by the high-speed rotating spiral-notched blades in the device and pushed to the non-seeding area for the purpose of cleaning the seeding belt. The parameters of key components were determined through theoretical analysis. The orthogonal combination test method of four factors and three levels was adopted. The EDEM discrete element simulation experiment was carried out by selecting the straw mulching quantity (SMQ), the rotating speed of the active rotating shaft (RSARS), the forward speed of the tractor (FST), and the notch width of the spiral notch blade (NWSNB) as the test factors, and the straw-cleaning rate (SCR) and soil loss rate (SLR) as the test indexes. Through range analysis, the parameters were optimized, and the optimal operation parameters of the straw row-sorting device were determined as follows: SMQ was 1.8 kg/m2, RSARS was 120 rpm, FST was 4 m/s, and NWSNB was 9 mm. The operational performance of the device was verified by field experiments. The results of the test showed that after the device was operated with the optimal combination of parameters, the SCR of the 20 cm wide seeding belt was 95.32%, and the SLR was 7.12%, which met the agronomic and technical requirements of corn no-tillage sowing operation in Northeast China. This study can provide a reference for the design of a straw row-sorting device of a no-tillage machine.

Structural Behavior of a Fixed-End Arched Cellular Steel Beam without Lateral Support

The arched cellular beam has the advantages of both the solid-web arch and the straight beam with web opening, and has become increasingly admired by architects in recent years. In this paper, four arched cellular beam specimens are designed using an orthogonal test method (OTM) with a three-factor and two-level approach. Firstly, the static loading test is carried out to analyze the mechanical response of the arched cellular beam under concentrated load. Then, a numerical analysis based on ABAQUS finite element (FE) software is carried out. The results show that the simulation results agree well with the test results, which indicates the accuracy of the simulation analysis method. Finally, the buckling load of the arched cellular beam under three different loads is calculated using the variable parameter FE analysis. Combined with the range analysis in the OTM, the influence of the target factor on the buckling load of the arched cellular beam is determined. The results show that the order of the factors affecting the out-of-plane elastic buckling is rise–span ratio > web height–thickness ratio > diameter–depth ratio.

Analytical Estimation of Strain Energy Accumulation in Retreating Longwall Mining and Sensitivity Analysis Using the Orthogonal Testing Method

AbstractExcessive strain energy accumulation in the coal seam is one of the essential conditions for rockbursts to occur. It is imperative to understand the parameters that affect the strain energy accumulation in retreating longwall mining to optimise the design and minimise rockbursts occurrences. In this paper, new analytical models were developed to calculate the strain energy accumulation considering the current state-of-the-art longwall machinery being used in the industry. Seven parameters, i.e., mining depth, length of the cantilever roof, coal seam thickness, thickness of the immediate roof, Young’s modulus of coal and the roof, and Poisson’s ratio of the coal seam, were identified as the parameters affecting the strain energy accumulation. A detailed statistical analysis of the parameters was conducted using the orthogonal testing method, which revealed that mining depth, Young's modulus of coal and the coal seam thickness significantly influence the strain energy accumulation within a 99% confidence interval.

Analysis of Influencing Factors on Silicon Epitaxial Growth in Horizontal Single‐Wafer Reactor through Orthogonal Test

AbstractSilicon epitaxy is a crucial process used in semiconductor manufacturing to deposit high‐quality films of silicon. This technique is widely used in the production of integrated circuits, as it enables the fabrication of intricate electronic structures with enhanced performance characteristics. This study conducts numerical simulations on a chemical vapor deposition (CVD) reactor to explore the impact of process parameters on the growth rate and non‐uniformity of silicon. The investigation encompasses both the gas and surface reactions of the trichlorosilane‐hydrogen (TCS‐H2) system. The distributions of gas flow velocity, temperature, and main components are systematically studied by varying the process parameters, including susceptor temperature, inlet gas velocity, susceptor rotating speed, inlet gas temperature, upper wall temperature, and TCS mole fraction. Furthermore, the orthogonal test method is introduced to assess the effect of all parameters on the growth non‐uniformity. The results reveal that the inlet gas velocity and susceptor temperature have a significant influence on the growth rate and non‐uniformity. The silicon growth rate is primarily influenced by the TCS mole fraction, whereas the rotation speed of the substrate primarily influences the growth non‐uniformity of growth. Finally, the optimal scheme is proposed as valuable guidance for enhancing silicon chemical vapor deposition processes in industrial applications.

Heat Transfer and Fluid Flow Characteristics of Microchannel with Discrete Double Inclined Ribs on Sidewalls

The heat transfer and fluid flow characteristics of microchannel with discrete double inclined ribs on sidewalls is performed numerically. A three-dimensional numerical model of the microchannel is constructed and studied. To obtain the optimal microchannel, four structural parameters of the rib length, angle, thickness, and height are changed by the orthogonal test method. In addition, four structural parameters of the rib are investigated separately on the heat transfer and fluid flow characteristics of the microchannel, Nusselt number, friction factor and performance evaluation criterion of the microchannel are calculated with Reynolds number ranging from 200 to 600. Results indicate that the microchannel with discrete double inclined ribs on sidewalls exhibits superior thermal characteristics, which shows a 58.13% reduction in temperature difference between the maximum temperature and the inlet temperature compared to the straight-through channel. Furthermore, all four structural parameters of the rib have varying degrees of effect on the heat transfer and fluid flow characteristics of the microchannel.

Optimization of the dosage of chopped basalt fibers in asphalt pavement surface course materials for semi-rigid base with functional requirements.

How to select suitable pavement materials for asphalt pavements according to the functional requirements of layers is still the focus of research by scholars in various countries. However, their effectiveness in combating high-temperature rutting and fatigue cracking in middle and lower layers is limited. To address this issue, a study optimized the incorporation of basalt fibers in different layers to improve road performance based on design specifications. Nine asphalt pavement structures with varying amounts of basalt fibers were assessed using an orthogonal test method. The optimal structure was determined considering factors such as fatigue life and overloading using the finite element method for modeling. Results showed that fiber dosage had a minimal impact on road surface bending subsidence and the location of tensile strain in the lower layer. Shear stresses were concentrated mainly at the outer edges of loads. Optimal dosages of basalt fiber were determined for different layers: 0.3% for the upper layer, 0.1% for the middle layer, and 0.3% for the lower layer. The optimal structure consists of a strong base with a thin-surfaced semi-rigid base layer, with 0.3% for the upper layer and 0.1% for the middle layer. This study provided valuable insights into designing basalt fiber asphalt pavement structures.

Experimental evaluation of fatigue performance of recycled asphalt mixture using refined separation recycled aggregates

In order to improve the utilization of reclaimed asphalt pavement (RAP) in recycled asphalt mixtures (RAMs), RAP was firstly separated into recycled mortar and coarse refined separation recycled aggregates (CRSRAs) with different particle sizes based on a laboratory refined separation method. Meanwhile, the process parameters for RAP separation were optimized by using the orthogonal test method. The related properties of the aggregates before and after refined separation, including residual bitumen binder content, particle agglomeration, angularity, and sphericity, were characterized. The cumulative distribution of sphericity of CRSRAs was fitted with the Weibull function. Asphalt mixtures with 0, 30%, and 50% RAP content were prepared by the Marshall design method. Moreover, the indirect tensile dynamic modulus and fatigue life of these asphalt mixtures after different water immersion periods were evaluated. The results showed that the CRSRAs had a residual binder content less than 1.0% and fewer pseudo particles after refined separation. Furthermore, a bitumen-rich mortar with a particle size less than 2.36 mm and a bitumen content of 10–14% was obtained. Angularity and Weibull fitting results verified that refined separation could homogenize RAP and obtain CRSRAs with a low variability, which helps to prepare better RAMs with high RAP content. RAMs prepared with CRSRAs exhibit superior fatigue performance compared to the traditional RAMs. Their fatigue life was less sensitive to stress changes and fluctuated little with the increasing water immersion time.

Preparation of cementitious osmotic crystalline waterproof material and its waterproofing mechanism analysis

Cementitious Capillary Crystalline Waterproofing materials (hereinafter: CCCW) with the advantages of good waterproof effect, green and low cost, it is widely used in the field of building waterproofing. Researchers and scholars have studied the proportioning of such materials. However, the experimental methods used in these studies are not perfect enough, therefore, this study uses a seven-factor, two-level orthogonal test method to conduct experiments and to study the waterproofing effect of CCCW coated on the substrate at different ages, and to discuss the existing waterproofing mechanism in conjunction with it. The results show that the group's homemade waterproofing agent has a good waterproofing effect, and the compressive strength is significantly increased at different ages, which suggests that CCCW can promote the hydration of cement and produce more penetrating crystals, thus blocking the capillary pores and microcracks, and making the matrix dense and waterproof.

Mechanism and property optimization of stainless steel slag for preparation of cementitious materials

The effective utilization of stainless steel slag on a large scale has posed a persistent challenge. To address this problem, this study used the orthogonal test method to investigate the optimisation of the ratio of stainless steel slag preparation cementitious materials while exploring the curing mechanism of metallurgical solid waste materials and its stability and the leaching of heavy metals. The experimental results revealed that the optimal combination consisted of 59% granulated blast furnace slag(GBFS), 35% stainless steel slag(AODS), and 6% desulfurization gypsum(DG). This composition yielded impressive compressive strength values of 11.40 MPa at 3 days and 28.36 MPa at 28 days. The stainless steel slag(AODS) contains a large amount of highly reactive calcium-containing material, accelerating the hydration reaction for 7–28 days. Moreover, the 3CaO·2SiO2·3 H2O(C-S-H) dense layered structure and related products produced by the hydration reaction can effectively encapsulate the Cr2O3 particles. As a result, the strength, stability and safety of the cementitious materials were significantly improved.

Formulation development of metakaolin geopolymer with good workability for strength improvement and shrinkage reduction

This study aims to optimize formulation and preparation of metakaolin based geopolymer for good workability, high compressive strength, and reduced drying shrinkage by considering alkaline activator composition, liquid to solid mass ratio, curing condition, and admixtures. The optimized geopolymer paste was further modified by granulated blast furnace steel slag (GBFS) and ordinary Portland cement (OPC) as calcium sources and carbon fibers as reinforcing additive for further strength improvement and shrinkage alleviation, in which the improvement mechanisms were manifested through mechanical strengths and microstructure observations. An optimized combination of modifiers and curing condition was obtained by Orthogonal Array Testing method. Experimental results indicate that sodium silicate is essential in the synthesis of alkali activator with nominal composition of Na2O·1.3SiO2·10.8H2O for strength development and cracking prevention. Good workability and high compressive strength of paste specimens could be attained by liquid to solid mass ratio of 1.21 between alkaline activator and metakaolin with ambient curing. The modified geopolymer pastes presented further improved compressive strength and reduced drying shrinkage. The microstructure images showed that the formation of cement hydration products, ettringite crystals, and more condensed matrix structure by using OPC as additive in geopolymer. The optimized geopolymer paste was made with 2% carbon fiber, 33% Portland cement and 10% GBFS and cured at ambient temperature achieved ultimate compressive strength of 73 MPa with reduced drying shrinkage. This ultimate compressive strength was 55% and 65% higher than non-modified geopolymer and ordinary Portland cement pastes, respectively, and was higher than 80% values in related studies.

Research on energy-saving renovation of solar greenhouses based on multiple factors and multiple objectives

The applicability of the traditional energy-saving renovation method for greenhouses is limited and influenced by the subjective decisions of researchers. Therefore, in this paper, a multifactor and multiobjective unbiased evaluation method is proposed based on the orthogonal test and entropy methods to study energy-saving transformation of solar greenhouses. The results show that the thickness of the gas layer, type of front roof glass and thermal insulation material of the rear roof greatly influence energy consumption, accounting for 45.5 %, 34.4 % and 15.3 %, respectively, of the total energy consumption, followed by the type of gas, thickness of glass and thermal insulation material of the heat storage wall, accounting for 3.2 %, 1.1 % and 0.5 %, respectively, of the total energy consumption. Based on energy savings, carbon emission reduction, investment cost and payback period, all renovation cases are comprehensively analyzed by the entropy weight method. The results show that Case m is the best renovation case, i.e., the front roof comprises three-layer glass, the glass thickness is 3 mm, the width of the cavity is 6 mm, which is filled with krypton gas, the rear roof insulation material is 100-mm thick extruded polystyrene (XPS), and the heat storage wall insulation material is 100-mm thick expandable polystyrene (EPS). This renovation method provides a systematic and objective theoretical basis for energy-saving renovation of solar greenhouses in cold regions.

Изучение параметров деформации оттаивающих грунтов на основе дисперсионного анализа и метода анализа иерархий

Purpose: To study the statistical significance of many factors: the initial temperature of the soil sample T0, humidity ω, confining pressure σ3 and loading frequency f on the deformation parameters of thawing soils by the method of orthogonal tests. Based on the method of weight analysis, to study the influence of the weight of various factors on the results of dynamic triaxial tests. To set the regression equation for the deformation parameters. Method: Analysis of Variance (ANOVA) is used to test the statistical significance of factors based on orthogonal tests. Using the Analytic Hierarchy Process (AHP), the influence weights of factors on test results are determined through matrix calculations. Results: Test factors: T0, ω, σ3 and f have strong statistical significance for test results. The influence of humidity on test results is more than 50%. The multiple linear regression equation fits the test results well. Practical significance: The orthogonal testing method, based on ANOVA and AHP, has the advantage expressed in a small number of trials, a wide coverage of factors, and the analysis of influence weights. The results of ANOVA and weight analysis show that moisture has the greatest influence on the deformation of the subgrade of thawing soils. During the operation of the subgrade, changes in soil moisture must be strictly controlled to prevent engineering accidents.

Analysis of the Impact of Structural Parameter Changes on the Overall Aerodynamic Characteristics of Ducted UAVs

Ducted UAVs have attracted much attention because the duct structure can reduce the propeller tip vortices and thus increase the effective lift area of the lower propeller. This paper investigates the effects of parameters on the aerodynamic characteristics of ducted UAVs, such as co-axial twin propeller configuration and duct structure. The aerodynamic characteristics of the UAV were analyzed using CFD methods, while the impact sensitivity analysis of the simulation data was sorted using the orthogonal test method. The results indicate that, while maintaining overall strength, increasing the propeller spacing by about 0.055 times the duct chord length can increase the lift of the upper propeller by approximately 1.3% faster. Reducing the distance between the propeller and the top surface of the duct by about 0.5 times the duct chord length can increase the lift of the lower propeller by approximately 7.7%. Increasing the chord length of the duct cross-section by about 35.3% can simultaneously make the structure of the duct and the total lift of the drone faster by approximately 150.6% and 15.7%, respectively. This research provides valuable guidance and reference for the subsequent overall design of ducted UAVs.

Influence of a Meltblown Die with a Laval Airstream Channel on the Manufacturing Process of a Polymer Fiber Based on an Orthogonal Test and Simulation Analysis.

A Laval nozzle is a device that accelerates a low-speed airstream to form a high-speed airstream. In this work, we use a Laval nozzle in the airstream channel design of a meltblown die to improve the tensile properties of the fiber in the airstream field of the meltblown die. The features of the airstream field of the meltblown die are analyzed by numerical simulation. For a given parametrization, six factors may be tuned to optimize the performance of the Laval airstream channel of the meltblown die. We thus use a five-level, six-factor orthogonal test method to optimize the airstream channel of the meltblown die to determine the various factors that influence the airstream field beneath the meltblown die. The results show that the optimized Laval meltblown die performs better than the traditional die and that the widths of the larynx and expansion segment most strongly affect the airstream velocity beneath the Laval meltblown die. Compared with a traditional die, the Laval die optimized by orthogonal testing increases the peak airstream velocity by 17.54%, average velocity by 96.81%, average temperature by 12.32%, and peak pressure by 14.61% and produces weaker turbulence intensity near the spinneret. These characteristics make the airstream beneath the die more stable and uniform and accelerate the attenuation of the fiber diameter, producing more polymer nanofibers. These results demonstrate a valuable approach to the design and optimization of meltblown dies and provide a technical reference for the production and application of the meltblown fiber production equipment.

Ultrasonic assisted pecking drilling process for CFRP/Ti laminated materials

Carbon fiber reinforced polymer (CFRP)/titanium alloy (Ti) laminated materials are widely used in aerospace and marine industries because of their excellent physical and electrochemical properties. The extensive demand requires a higher level of hole making technology to reduce the material damage caused by hole making. In this paper, we adopt a novel machining method, which combines Ultrasonic Assisted Drilling (UAD) and pecking drilling to generate a new machining method, Ultrasonic Pecking Drilling (UPD). Based on this, this study compares Conventional Drilling (CD), UAD and UPD in terms of thrust using orthogonal test method. In this paper, CFRP exiting delamination damage is investigated for three processing methods, and indirect measurement of interface temperature as well as detection of CFRP entrance delamination damage are carried out for UPD process. In addition, the tool wear and the exit burr of titanium alloy are analyzed for the three processes under different parameters. The test results show that UPD performed better in terms of thrust, the lowest thrust force is reduced by 35.1 % and 14.8 % at low feeds, respectively. CFRP exit delamination and tool wear are also good compared to both CD and UAD. Compared to CD, the maximum delamination damage decreased by 6.37 %. Besides, UPD results in better hole surface quality, where the roughness can be reduced by up to about 40 %. The obtained results show that UPD is a worthwhile option for drilling CFRP/Ti laminated materials.

Design and experiment of a soybean shaftless spiral seed discharge and seed delivery device

When the driven stubble-breaking and anti-blocking no-till planter operates in the Southwest China, the stubble-breaking blades will impact with the ground as they cut through the soil and straw stubble, causing the planter to vibrate. This results in poor performances of the seed discharge by seed discharger and the seed guide by the seed guide tube. Based on the principle of spiral conveying, a soybean shaftless spiral seed discharge and seed delivery device was designed. The optimum seed filling size and speed range of the spiral blade were obtained by analyzing the size, force, and motion of soybean seeds of "ZhongHuang 37". The quadratic regression orthogonal rotation test and response surface method were used to analyze the operating parameters of the shaftless spiral seed discharge and seed delivery device by joint EDEM (Discrete Element Method)-RecurDyn simulation. The optimum parameters were obtained: the spacing of spiral was 11.4 mm, spiral outer radius was 5.5 mm, spiral inner radius was 2.9 mm and rotation speed was 10.4 r·s−1. Based on simulation and optimization results, the device was trialed and its field performance was tested. The results showed that at a surface slope of 16.1°, an average surface flatness of 8.9 cm, an average planter vibration frequency of 75.2 Hz, and an average amplitude of 7.2 mm, the average seeding qualification index, multiple index, missing seeding index, and damage index of the shaftless spiral seed discharge and seed delivery device were 92.6%, 5.03%, 2.4% and 0.92%, respectively, which were in line with the local agronomic requirements. The designed soybean shaftless spiral seed discharge and seed delivery device meets the requirements of the quality of no-till seeding and can provide a reference for the design and improvement of seed discharger and seed guide tube under poor ground leveling and long-distance seed delivery conditions.

Study of rib protection devices based on resistant muffler theory for transcostal focused ultrasound therapy

High-intensity focused ultrasound (HIFU) is one of the effective means of treating cancer. One of the current challenges in HIFU treatment is how to minimize thermal damage to the rib during transcostal HIFU treatment and ensure that sufficient energy is delivered to the target area. In this paper, a sound insulation device mounted in front of the rib is proposed to address this challenge. The device is designed based on resistant anechoic theory, combining both reflective and resonant sound energy-blocking mechanisms to enhance the transmission loss and filter bandwidth. The structural parameters of the device are optimized using an orthogonal test method. A finite element method was used to simulate the sound and temperature fields of the sound insulation device with and without different rib spacings. The simulation results demonstrate a significant decrease in sound pressure at the ribs under the protection of the sound insulation device, with no significant difference in sound pressure at the target area. Consequently, the temperature at the ribs decreases, while the temperature at the target area tissue is guaranteed. Furthermore, transcostal HIFU experiments are conducted using real pig ribs and the experimental results validate the accuracy of the simulation results.

Groove parameters optimization of rotary excitation control valve using computational fluid dynamics coupled with response surface method

A rotary excitation control valve is proposed in this paper. In order to study the interaction of the valve core groove parameters on the output flow velocity and pressure of the rotary excitation control valve, a dynamic simulation of the internal flow field of the rotary excitation control valve is carried out based on the Multiple Reference Frame Model (MRF), and the simulation results are experimentally verified. Based on the quadratic regression orthogonal test method, a significant non-lossy regression model of the groove parameters with the output flow velocity and pressure is established, and the response surface of the groove parameter interaction is obtained. The results show that the influence of groove parameters on flow velocity is in the order of width > depth > length, and the interaction between length and depth is the most significant; the influence of groove parameters on pressure is in the order of width > depth > length, and the interaction between width and depth is the most significant. The Response Surface Methodology (RSM) is used to optimize the groove parameters, and the best combination of groove parameters obtained is 20.00 mm in length, 5.65 mm in width and 8.00 mm in depth.