Biosystems Engineering最新文献

Drip irrigation using a high-performance pressure-compensating (PC) emitter is one of the essential components for precision agriculture, and it is necessary to accurately predict its performance prior to design. In this study, an efficient two-way fluid–structure interaction (FSI) simulation model was developed and verified through an enlarged model experiment. The computational fluid dynamics (CFD) and computational solid mechanics (CSM) models of the FSI simulation were systematically verified, and a calibration method for the overestimated flow rate in the re-rising range was applied. The CFD model was determined to be the shear stress transport turbulence model, and the CSM model was determined to be the Ogden hyperelastic model for the PC emitter. The minimum prediction error for the flow rate was 7.93%, which was within 10% for all cases. The simulation model demonstrated its efficiency by analysing the performance of a single PC emitter with an average total analysis time of 18.6 h. In addition, by comparing various cases according to the design parameters, it is considered that the hardness of the diaphragm has a significant impact on the design of low-pressure PC emitters. The simulation model of this study can accurately predict the performance of PC emitter under specific conditions, yet improvement of simulation model is required to be applied in design optimisation. Future studies may benefit from combining an improved FSI simulation with a surrogate model to further enhance optimisation efforts.

The threshing cylinder will wear and deform during the threshing process, causing dynamic balance problems. The combine harvester has multiple vibration excitation sources and a complex vibration environment, making it challenging to extract weak unbalanced signals from strong background noise. A novel three-step filtering framework is proposed in this paper. A zero phase filter was used as the pre-processing layer to filter out the high frequency components in the original signal and reduce the number of parameter-adaptive variational mode decompositions (PAVMD) needed. The PAVMD was used to decompose the non-stationary vibration signal before Adaptive Neuron Linear (Adaline) function was used to fit sinusoidal signal parameters. A measurement index, termed the correlation amplitude (CA) index, is constructed. The parameterisation of PAVMD was guided by the CA index, and the modal component of the unbalanced fault features were located. The simulation and real cylinder signals proved that the proposed method could effectively extract unbalanced signals under noise interference, and the unbalance was identified accurately by the influence coefficient method. Experiments on a threshing cylinder showed that the amplitude identification error was <24 g in single-sided unbalance identification, and the amplitude identification error was <27 g in double-sided unbalance identification. The proposed method had high robustness and small identification error, especially under short-time working conditions, compared with other similar approaches.

To evaluate the resistance of apples to bruising under transient impact loads, a pendulum device was initially employed to gather collision data. Subsequently, an image acquisition and processing system was utilised to compute the apple surface bruise area, and X-ray computed tomography technology was utilised to precisely calculate the bruise volume. Based on the CT image and bruise area image analysis, the difference between bruised area and normal tissue on the apple after collision, and effects of impact energy on apple bruising volume and bruise area has been elaborated in detail. Results analysis revealed a general increase in both bruise volume and bruise area with escalating impact energy, and there is a strong correspondence between bruise volume and bruise area across different storage days and impact energies. The relationship between bruise volume and bruise area under different storage duration were also established. On the base of bruise resistance index (BRI) model utilising impact energy and bruise volume as variables, those analysis led to the establishment of a new bruise resistance index (BRI*) model employing impact energy and bruise area as independent variables. The effectiveness of BRI* model in assessing apple bruise resistance was demonstrated by comparing the corresponding relative error for bruise thresholds of BRI and BRI* under the same condition. The relative error ≤3.3% underscores the accuracy of the new model and proves the proposed BRI* model to be an efficient and rapid tool for assessing the degree of apple bruising.

To address the challenge of uneven and inadequate deposition within the canopy and on the lower side of the leaves in vineyards spraying operations, the performance of new prototype air-disturbance sprayers was evaluated. Firstly, the optimal parameter combination under the swing type disturbance mode (SW) was determined through orthogonal analysis. Then, a multivariate variance analysis was employed to compare the performance indicators of SW with those found under the rotating type disturbance modes (anticlockwise rotating AR, and clockwise rotating CR), as well as with the blank control group. It has been confirmed that SW could increase the penetration of droplets within the canopy and obtain the optimal deposition uniformity (58.72%). This mode did not affect the canopy deposition, but it decreased the coverage of droplets on the lower side of the leaves (11.82%). AR achieved a deposition uniformity of 62.06% and could consistently ensure that the coverage of both sides of the leaf was over the threshold of 30%. However, it decreased the canopy deposition. Generally speaking, CR not only significantly increased the canopy deposition, but also improved the deposition uniformity to 60.94% (second only to SW). Although the coverage on the lower side of the leaf for CR (25.41%) has not yet reached the threshold requirement of 30%, it could be anticipated that the implementation of two-sided spraying could effectively solve this deficiency. Therefore, the future positioning of a clockwise rotating turbulence system at the airflow outlet of the air-assisted sprayer will be a valuable choice.

Upflow anaerobic sludge blanket (UASB) reactors are widely used for wastewater treatment in tropical regions, yet the resulting effluent requires further post-treatment to meet the quality standards for a safe discharge or reuse. This study proposes a novel technology for the post-treatment of effluents from UASB reactors, high rate algal ponds (HRAP). Firstly, experimental data from two pilot HRAP treating the primary effluent from an UASB reactor was used to calibrate a mathematical biokinetic model (BIO_ALGAE). Then, different operational strategies were simulated by varying the HRAP hydraulic retention time (HRT) (4, 6, and 8 days) and footprint, water quality, and bioenergy production, considering a wastewater treatment plant of 10,000 population equivalent. Experimental results showed a removal efficiency of 70% for the chemical oxygen demand, 42% for total suspended-solids, 57% for ammonium nitrogen, and 30% for orthophosphate in the pilot plant. According to the calibrated model output, the quality of the effluent is similar with HRT of 6 and 8 days, but with a HRT of 4 days N removal would be compromised. Bearing in mind that the lower the HRT, the lower the footprint of the wastewater treatment plant, 6 days seems a important trade-off. The findings of this study are promising, presenting a new conception for treating effluents from UASB reactors. This could enhance the quality of wastewater treatment in tropical countries and suggest potential uses for the generated by-products.

3D reconstruction of seedling can provide comprehensive and quantitative spatial structure information, offering an effective digital tool for breeding research. However, accurate and efficient reconstruction of seedling is still a challenging work due to limited performance of depth sensor for seedling with small-size stem and unavoidable error for multi-view point cloud registration. Therefore, in this paper, we propose an accurate multi-view 3D reconstruction method for seedling using 2D image contour to constrain 3D point cloud. The rotation axis is calibrated and optimised by minimising point-to-contour distance between 2D image contour and projected exterior points from 3D point cloud. Then, to remove outliers and noise, we introduce the seedling mask of 2D image to constrained and delete projected outlier points of 3D model from corresponding view. Furthermore, we propose a residual-guided method to recognise missing region for 3D model and complete 3D model of small-size stem. Finally, we can obtain an accurate 3D model of seedling. The reconstruction accuracy is evaluated by average distance between projected contour of 3D model and 2D image contour of all views (0.3185 mm). Then, the phenotypic parameters were calculated from 3D model and the results are close to manual measurements (Plant height: R² = 0.98, RMSE = 2.3 mm, rRMSE = 1.52%; Petioles inclination angle: R² = 0.99, RMSE = 0.73°, rRMSE = 1.41%; Leaf area: R² = 0.66, RMSE = 1.05 cm², rRMSE = 7.63%; Leaf inclination angle: R² = 0.99, RMSE = 1.01°, rRMSE = 1.72%; Stem diameter: R² = 0.95, RMSE = 0.12 mm, rRMSE = 5.43%). Breeders can improve the selection of more resilient varieties and cultivars to different growing conditions starting from the dynamic analysis of their phenotype.

Computational fluid dynamics (CFD) simulations have been extensively used in designing air distribution systems for controlled environment agriculture (CEA). In recent years, more application studies using CFD simulations can be found for vertical farms due to the increasing interest in indoor vertical farming systems. However, it is well-known that CFD simulations are sensitive to many computational parameters and settings. The requirement of a crop response model in the CFD simulation for a vertical farm makes it even more complicated. Despite increased interest, guidelines for CFD simulations in vertical farms are scarce based on a literature study. Therefore, a systematic sensitivity analysis is conducted for a small generic multi-layer vertical farm with sole source lighting, which was the object of study in the literature before. The impact of a wide range of computational and physical parameters is investigated, including grid resolution, turbulence model, turbulence intensity, discretisation scheme, drag coefficient of the crops and computational time. The analysis shows that in this case (inlet Re = 46,923, Ar = 0.078, cultivated with lettuce), the RNG k-ε turbulence model outperforms other commonly used two-equation turbulence models. Compared to the experimental results from the literature, the simulation results from the first-order upwind scheme show large discrepancies, especially on the coarse grid. Although the influence of drag coefficient on the airflow inside the crop canopy is pronounced, little difference is observed in the air distributions in the vertical farm away from the crops.

It is challenging to control pathogens in contaminated seeds without damaging seed vigour by using heat treatments. In this study, a treatment process for pasteurising watermelon seeds was developed using the emerging technology of radio frequency (RF) energy. To reduce the temperature difference between the layers, the polypropylene frame (covering 40% of the sample surface area) with the inside medium of air was added to the centre of the first layer. The length, width, height, and thickness of the polypropylene frame were 134, 94, 17, and 2 mm, respectively. The optimised process involved that seeds with stacked four layers were heated by RF energy for 6.5 min followed by holding in the hot air oven at 64.5 ± 0.5 °C for 50 min. After that, samples with separated four layers were dried in the hot air oven for 30 min followed by cooling for 6 min in forced ambient air (6.0 ± 0.1 m s⁻¹). This treatment produced in excess of a 4-log reductions of Acidovorax citrulli while differences in germination rate, germination energy, vigour index, germination index, and leachate electrical conductivity were insignificant (P > 0.05) between control and the optimised process treated seeds. Meanwhile, the average moisture content of seeds was reduced to 8.05% wet basis after pasteurising. These findings can further be expanded to develop potential industrial applications of RF pasteurisation for maintaining quality in agriculture products.

To investigate the hydraulic effects and performance of the micro-pressure filtration and cleaning tank under conditions with sandy and brackish water, physical model tests were conducted with five groups of flow rates (6–14 m³ h⁻¹), four groups of sediment contents (0.5–2.0 g l⁻¹), five groups of mineralisation degrees (0–5.0 g l⁻¹), and three groups of screen apertures (0.125, 0.150, and 0.180 mm). Dimensional analysis, multiple linear regression analysis, and the non-dominated sorting genetic algorithm II (NSGA-II) were used to analyse the test results. The results showed that the optimal operating conditions of the micro-pressure filtration and cleaning tank under the scope of this test were a screen aperture of 0.175 mm, a flow rate of 13 m³ h⁻¹, a sediment content of 1.8 g l⁻¹, and a mineralisation degree of 4.7 g l⁻¹. The micro-pressure filtration and cleaning tank was intermittently discharged and rinsed, the discharge time was 30–40 s, and the flow rate of discharge and rinsing was 5.54 m³ h⁻¹. Prediction models of the head loss and the filtration efficiency of the filter were established. The coefficients of determination (R²) were greater than 0.9, the average relative errors of the predicted and measured values were 2.98% and 2.17%, respectively, and the corresponding root mean square errors were 0.0549 m and 0.642. The research results can be used as a reference for in-depth investigations on the performance of the micro-pressure filtration equipment in front of pumps.

Sugarcane tip cutting is essential to reducing the rate of impurities in the harvest. To achieve adaptive regulation of the tip-cutting position by a sugarcane harvester, we propose a method for estimating the height of the tip-cutting position of sugarcane. The RGB and Binocular depth cameras are aligned to process the sugarcane tip region image. This involves threshold segmentation, morphological operations, and contour detection to identify the tip-cutting position and upper boundary contours. The depth image is segmented using contour pixel information and merged to form a colour depth image of the sugarcane's tip. This image is then transformed using depth data and triangular parallax principles to determine the height of the sugarcane tip-cutting position. The proposed method was evaluated in various sugarcane plantation environments. Comparative analysis between the proposed method and manual measurements of actual cutting position heights revealed that the RMSE ranged from 1.22 cm to 1.78 cm, and R² varied between 0.79 and 0.86. These results demonstrate the effectiveness of the proposed method in accurately extracting the height information of sugarcane tip-cutting positions, which has a specific application value for the adaptive adjustment of the tip-cutting device of the sugarcane harvester.