Biosystems Engineering最新文献

An application oriented all-round intelligent weeding machine with enhanced YOLOv5 以应用为导向的全方位智能除草机，配备增强型 YOLOv5

IF 4.4 1区农林科学 Q1 AGRICULTURAL ENGINEERING

Biosystems Engineering

Pub Date : 2024-11-17 DOI: 10.1016/j.biosystemseng.2024.11.009

Meiqi Xiang, Xiaomei Gao, Gang Wang, Jiangtao Qi, Minghao Qu, Zhongyang Ma, Xuegeng Chen, Zihao Zhou, Kexin Song

Nobody would contest that physical weed removal methods offer numerous advantages over biochemical alternatives. Within the domain of intelligent mechanical weed control, comprehensive research targeting the entire intelligent weeding machine system remains relatively scarce. To expedite the practical application of intelligent weeding machines, this study explored an enhanced YOLOv5 model with one colour constancy module, which aimed at achieving higher accuracy in crop seedling detection. An innovative "separating and closing" strategy, which allows the machine to precisely avoid crop seedlings while effectively weeding the areas between crop seedlings was employed to facilitate intra-row weeding. By integrating this strategy with a comprehensive design of the mobile platform, inter-row weeding actuators, and harmonious control of these key components, this research successfully developed an intelligent weeding machine capable of simultaneously performing intra-row and inter-row (all-round) weeding. Compared with previous studies, this study put the emphases on complex farm lighting conditions, both inter-row and intra-row weeding functions, and weed regrowth. Field experiments conducted in lettuce (Lactuca sativa var. ramosa Hort.) fields at four different locations on three separate dates demonstrated that this intelligent weeding machine achieved average weeding rates, crop seedling damage rates, and regrowth rates of 96.87%, 1.19%, and 0.34%, respectively. The ability to perform all-round weeding simultaneously is a significant advance in mechanical weeding control. The design and methodology employed in this study have broad implications for advancing the field of precision agriculture and addressing the growing demand for sustainable farming practices.

没有人会质疑物理除草方法比生化除草方法具有诸多优势。在智能机械除草领域，针对整个智能除草机系统的综合研究仍然相对较少。为了加快智能除草机的实际应用，本研究探索了带有一个颜色恒定模块的增强型 YOLOv5 模型，旨在实现更高的作物幼苗检测精度。该研究采用了创新的 "分离和闭合 "策略，使机器能够精确地避开作物秧苗，同时有效地对作物秧苗之间的区域进行除草，以促进行内除草。通过将这一策略与移动平台、行间除草执行器的综合设计以及对这些关键部件的协调控制相结合，本研究成功开发了一种能够同时进行行内和行间（全方位）除草的智能除草机。与以往的研究相比，本研究将重点放在复杂的农场光照条件、行间和行内除草功能以及杂草再生等方面。在三个不同日期、四个不同地点的莴苣（Lactuca sativa var. ramosa Hort.）田中进行的田间试验表明，该智能除草机的平均除草率、作物幼苗损伤率和再生率分别为 96.87%、1.19% 和 0.34%。能够同时进行全方位除草是机械除草控制的一大进步。本研究采用的设计和方法对推动精准农业领域的发展和满足对可持续农业实践日益增长的需求具有广泛的意义。

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引用次数: 0

Characterising vibration patterns of winter jujube trees to optimise automated fruit harvesting 表征冬枣树的振动模式，优化果实的自动采摘

IF 4.4 1区农林科学 Q1 AGRICULTURAL ENGINEERING

Biosystems Engineering

Pub Date : 2024-11-16 DOI: 10.1016/j.biosystemseng.2024.11.004

Zhouzhou Zheng , Yaohua Hu , Jianxin Dong , Pengfei Zhao , Yixue Liu , Xintong Jiang , Yichen Qiao , Shangpeng Sun , Yuxiang Huang

Understanding jujube tree dynamic characteristics is crucial for the design and invention of a catch-and-shake machine for fruit harvesting. Currently, the study of vibration characteristics based on the finite element method is the mainstream method for different types of fruit trees. However, limited by the lack of an accurate 3D tree model, there are still gaps between existing simulation analysis and actual tests to explore vibration characteristics. Specifically, the vibration mechanism of winter jujube trees is still unclear in jujube orchards. To address the issue, a multi-view 3D reconstruction technique is employed to acquire precise 3D tree models for simulation analysis. The obtained results from experiments indicate that the determination coefficient R² of the trunks and branches diameter are 0.96 and 0.91 between reconstructed and actual measurement results. Subsequently, material properties of jujube tree are measured to conduct model analysis and harmonic response analysis to find the optimal frequency range (10–20 Hz) in which a considerable vibration response can be obtained at low vibration energies. Moreover, transient analysis and test experiments are conducted to explore the energy transfer properties under different vibration frequency. Results showed that the acceleration response gradually increased from the bottom to the top of the branch on most branches at non-resonant frequencies. The proposed method can provide informative insights on the design of high-efficiency and low-energy jujube catch-and-shake harvesters.

了解枣树的动态特性对于设计和发明用于果实采收的接果摇摆机至关重要。目前，基于有限元法的振动特性研究是针对不同类型果树的主流方法。然而，受限于缺乏精确的三维果树模型，现有的仿真分析和实际试验在探索振动特性方面仍存在差距。特别是在枣园中，冬枣树的振动机理尚不清楚。针对这一问题，我们采用了多视角三维重建技术来获取精确的三维树木模型，以进行仿真分析。实验结果表明，重建结果与实际测量结果之间树干和树枝直径的判定系数 R2 分别为 0.96 和 0.91。随后，测量了枣树的材料特性，以进行模型分析和谐波响应分析，从而找到最佳频率范围（10-20 Hz），在该频率范围内，可在低振动能量下获得可观的振动响应。此外，还进行了瞬态分析和测试实验，以探索不同振动频率下的能量传递特性。结果表明，在非共振频率下，大多数树枝的加速度响应从树枝底部到顶部逐渐增加。所提出的方法可为设计高效率、低能耗的红枣捕获和摇动收割机提供有益的启示。

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引用次数: 0

UAV multispectral remote sensing for agriculture: A comparative study of radiometric correction methods under varying illumination conditions 无人机多光谱农业遥感：不同光照条件下辐射校正方法的比较研究

IF 4.4 1区农林科学 Q1 AGRICULTURAL ENGINEERING

Biosystems Engineering

Pub Date : 2024-11-15 DOI: 10.1016/j.biosystemseng.2024.11.005

Yuxiang Wang , Gert Kootstra , Zengling Yang , Haris Ahmad Khan

Unmanned aerial vehicles (UAVs) equipped with multispectral cameras have been widely used in precision agriculture. However, a notable challenge is the variation in ambient illumination, which affects the accuracy and reliability of UAV-based spectral-data acquisition. In this study, the aim is to evaluate and enhance the performance of existing radiometric correction techniques under varying illumination conditions, primarily concerning radiometric accuracy and homogeneity. Seven methods including three conventional methods and four new methods were employed for correcting the MicaSense Altum multispectral system which equips with a downwelling light sensor (DLS). Two specific strategies were adopted: (1) capturing reference panels at UAV flying altitudes, and (2) strategically placing multiple sets of reference panels throughout the study area. The result shows that calibrating images one time, for instance, the empirical line method (ELM), is seriously affected by the variable illumination. The commercial solution that using the DLS helps improve the uniformity of orthomosaics but lower its radiometric accuracy. Optimising the use of the DLS by capturing panels at the UAV's flight altitude can greatly improve accuracy. Additionally, when the DLS is unavailable, strategically placing multiple reference panels across the field and correcting calibration parameters for each image can effectively help mitigate the impact of varying illumination on generated reflectance orthomosaics. In conclusion, selecting suitable radiometric correction methods is crucial for UAV multi-spectral data collection when facing variable illumination conditions.

配备多光谱相机的无人飞行器（UAV）已广泛应用于精准农业。然而，一个值得注意的挑战是环境光照的变化会影响无人机光谱数据采集的准确性和可靠性。本研究旨在评估和提高现有辐射校正技术在不同光照条件下的性能，主要涉及辐射精度和均匀性。采用了七种方法（包括三种传统方法和四种新方法）对配备了下射光传感器（DLS）的 MicaSense Altum 多光谱系统进行校正。具体采用了两种策略：(1) 在无人机飞行高度捕捉参考板；(2) 在整个研究区域战略性地放置多组参考板。结果表明，一次性校准图像（例如经验线法（ELM））会受到多变光照的严重影响。使用 DLS 的商业解决方案有助于提高正射影像的均匀性，但会降低其辐射测量精度。通过在无人机飞行高度捕捉面板来优化 DLS 的使用，可以大大提高精度。此外，在无法使用 DLS 的情况下，战略性地在整个区域放置多个参考面板，并为每幅图像校正校准参数，可有效帮助减轻不同光照对生成的反射率正射影像图的影响。总之，面对多变的光照条件，选择合适的辐射校正方法对于无人机多光谱数据采集至关重要。

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引用次数: 0

Optimising maize threshing process with temporal proximity soft actor-critic deep reinforcement learning algorithm 利用时间临近软行为批判深度强化学习算法优化玉米脱粒过程

IF 4.4 1区农林科学 Q1 AGRICULTURAL ENGINEERING

Biosystems Engineering

Pub Date : 2024-11-05 DOI: 10.1016/j.biosystemseng.2024.11.001

Qiang Zhang , Xuwen Fang , Xiaodi Gao , Jinsong Zhang , Xuelin Zhao , Lulu Yu , Chunsheng Yu , Deyi Zhou , Haigen Zhou , Li Zhang , Xinling Wu

Maize threshing is a crucial process in grain production, and optimising it is essential for reducing post-harvest losses. This study proposes a model-based temporal proximity soft actor-critic (TP-SAC) algorithm to optimise the maize threshing process in the threshing drum. The proposed approach employs an LSTM model as a real-time predictor of threshing quality, achieving an R² of 97.17% and 98.43% for damage and unthreshed rates on the validation set. In actual threshing experiments, the LSTM model demonstrates an average error of 5.45% and 3.83% for damage and unthreshed rates. The LSTM model is integrated with the TP-SAC algorithm, acting as the environment with which the TP-SAC interacts, enabling efficient training with limited real-world data. The TP-SAC algorithm addresses the temporal correlation in the threshing process by incorporating temporal proximity sampling into the SAC algorithm's experience replay mechanism. TP-SAC outperforms the standard SAC algorithm in the simulated environment, demonstrating better sample efficiency and faster convergence. When deployed in actual threshing operations, the TP-SAC algorithm reduces the damage rate by an average of 0.91% across different feed rates compared to constant control. The proposed TP-SAC algorithm offers a novel and practical approach to optimising the maize threshing process, enhancing threshing quality.

玉米脱粒是谷物生产中的一个关键过程，优化这一过程对于减少收获后的损失至关重要。本研究提出了一种基于模型的时间临近软行为批判（TP-SAC）算法，用于优化脱粒滚筒中的玉米脱粒过程。所提出的方法采用 LSTM 模型作为脱粒质量的实时预测器，在验证集上，损坏率和未脱粒率的 R2 分别达到 97.17% 和 98.43%。在实际脱粒实验中，LSTM 模型对损坏率和未脱粒率的平均误差分别为 5.45% 和 3.83%。LSTM 模型与 TP-SAC 算法相结合，充当了 TP-SAC 的交互环境，从而可以利用有限的真实世界数据进行高效训练。TP-SAC 算法在 SAC 算法的经验重放机制中加入了时间邻近性采样，从而解决了脱粒过程中的时间相关性问题。在模拟环境中，TP-SAC 的性能优于标准 SAC 算法，表现出更高的采样效率和更快的收敛速度。在实际脱粒操作中，与恒定控制相比，TP-SAC 算法在不同喂入速率下平均降低了 0.91% 的损坏率。所提出的 TP-SAC 算法为优化玉米脱粒过程、提高脱粒质量提供了一种新颖实用的方法。

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引用次数: 0

Effects of polyphenol-rich extracts and compounds on methane and ammonia emissions from pig slurry during 28-day incubation 富含多酚的提取物和化合物对 28 天培养期间猪粪中甲烷和氨排放的影响

IF 4.4 1区农林科学 Q1 AGRICULTURAL ENGINEERING

Biosystems Engineering

Pub Date : 2024-11-05 DOI: 10.1016/j.biosystemseng.2024.11.002

Ali Heidarzadeh Vazifehkhoran , Johanna Pedersen , Lise Bonne Guldberg , Simon Svane , Henrik Karring , Anders Feilberg , Michael Jørgen Hansen

Animal manure in livestock production facilities is a major source of methane (CH₄) and ammonia (NH₃) emissions from agriculture. In this study, we investigated different polyphenol-rich extracts and chemicals including commercial chestnut tannin (CT), shea meal extract (SME) and lignosulfonic acid (LSA) in combination with 1 mM of urease inhibitors acetohydroxamic acid (AHA) and/or sodium fluoride (NaF) to mitigate CH₄ and NH₃ in an in-vitro setup with 0.5 L slurry reactors mimicking slurry pits in livestock facilities. Daily addition of pig feces and urine along with additives were conducted for 28 days at room temperature, while CH₄ and NH₃ emissions were monitored by cavity ring-down spectroscopy (CRDS) continuously. SME and SME + NaF added to slurry reduced CH₄ emission by 72% and 88%, and NH₃ emission by 45% and 52%, respectively. CT + NaF at the CT concentration of 2.6, 4.25 and 8.5 mg mL⁻¹, resulted in 48–55%, 70–72% and 81% reduction in CH₄ emission, and 17–29%, 40–49% and 49% reduction in NH₃ emission, respectively. Emission reduction based on the dosage of CT revealed that the relationship between dosage and emission reduction is not linear, therefore the reduction efficiency was calculated by emission reduction divided by concentration. CH₄ reduction efficiency at the CT concentration of 2.6, 4.25 and 8.5 mg mL⁻¹ were 18–21, 16–17 and 10 % (mg mL⁻¹)⁻¹. Therefore, the optimum dosage of CT was 4.25 mg mL⁻¹. In conclusion, addition of CT and SME along with NaF resulted in significant reductions of both CH₄ and NH₃ emissions, while supplementation of LSA and AHA to CT + NaF did not enhance the mitigation effect.

畜牧生产设施中的动物粪便是农业甲烷（CH4）和氨（NH3）排放的主要来源。在这项研究中，我们研究了不同的富含多酚的提取物和化学品，包括商用栗木单宁（CT）、乳木果油粕提取物（SME）和木质素磺酸（LSA），以及 1 mM 的脲酶抑制剂乙酰羟肟酸（AHA）和/或氟化钠（NaF），在体外模拟畜牧设施中的粪坑的 0.5 L 泥浆反应器中缓解 CH4 和 NH3。在室温下，每天添加猪粪便和尿液以及添加剂，持续 28 天，同时用空腔环降光谱（CRDS）连续监测 CH4 和 NH3 的排放。在泥浆中添加 SME 和 SME + NaF 后，CH4 排放量分别减少了 72% 和 88%，NH3 排放量分别减少了 45% 和 52%。CT + NaF 的 CT 浓度分别为 2.6、4.25 和 8.5 mg mL-1 时，CH4 排放量分别减少了 48%-55%、70%-72% 和 81%，NH3 排放量分别减少了 17%-29%、40%-49% 和 49%。根据 CT 的用量计算的减排量表明，用量与减排量之间不是线性关系，因此减排效率的计算方法是减排量除以浓度。在 CT 浓度为 2.6、4.25 和 8.5 毫克/毫升-1 时，CH4 的减排效率分别为 18%-21%、16%-17%和 10%（毫克/毫升-1）-1。因此，CT 的最佳用量为 4.25 毫克毫升-1。总之，在添加 CT 和 SME 以及 NaF 的同时，CH4 和 NH3 的排放量都显著减少，而在 CT + NaF 的同时添加 LSA 和 AHA 并没有增强减排效果。

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引用次数: 0

Scaled experimental study of a ventilation system featuring partition jet and pit exhaust 分区喷气和坑式排气通风系统的比例实验研究

IF 4.4 1区农林科学 Q1 AGRICULTURAL ENGINEERING

Biosystems Engineering

Pub Date : 2024-11-02 DOI: 10.1016/j.biosystemseng.2024.10.010

Qizhi Yang , Xi Bai , Guoqiang Zhang , Li Rong , Yao Tao , Jiyuan Tu , Jinyong Wang , Zhiru Hu , Jie Chai , Yong Wang

In the context of current intensive livestock farming development, we present a novel energy-efficient ventilation method, named as the partition jet and pit exhaust (PJPE) system, for multi-story pig facilities. The objective is to overcome the limitations of traditional ventilation methods, e.g., mixing ventilation sidewall air supply or tunnel ventilation, in managing heat stress and air quality. Isothermal and non-isothermal experiments were conducted in a 1:2.5 scaled pig pen model to study the airflow distribution characteristics and ventilation effectiveness of the PJPE system. The results demonstrate that the PJPE system enables rapid delivery of fresh air to the animal-occupied zone (AOZ). With the Archimedes numbers (Ar) of supply air ranging between 0.0025 and 0.0052, the jet maintains low air temperatures near the pig's back. Compared to traditional pig house ventilation methods, the PJPE demonstrates better heat removal efficiency (HRE), with an average HRE of 1.20. Additionally, the PJPE effectively inhibits the upward diffusion of ammonia from the slurry pit. These findings indicate that the PJPE system presents a viable, energy-efficient alternative for environmental control in high-density pig housing, highlighting its potential for advancing animal welfare and productivity in intensive livestock farming.

在当前集约化畜牧业发展的背景下，我们为多层养猪设施提出了一种新型节能通风方法，即分区喷气和坑式排气（PJPE）系统。其目的是克服传统通风方法（如混合通风侧壁送风或隧道通风）在管理热应力和空气质量方面的局限性。为研究 PJPE 系统的气流分布特性和通风效果，在 1:2.5 比例的猪栏模型中进行了等温和非等温实验。结果表明，PJPE 系统能快速向动物占用区（AOZ）输送新鲜空气。由于送风的阿基米德数（Ar）介于 0.0025 和 0.0052 之间，喷气机能在猪背附近保持较低的空气温度。与传统的猪舍通风方法相比，PJPE 显示出更高的热去除效率（HRE），平均 HRE 为 1.20。此外，PJPE 还能有效抑制泥浆池中氨气的向上扩散。这些研究结果表明，PJPE 系统为高密度猪舍的环境控制提供了一种可行的节能替代方案，凸显了其在集约化畜牧业中提高动物福利和生产率的潜力。

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引用次数: 0

Simulation and experimental study on frictional wear of plough blades in soil cultivation process based on the Archard model 基于 Archard 模型的土壤耕作过程中犁刃摩擦磨损模拟与实验研究

IF 4.4 1区农林科学 Q1 AGRICULTURAL ENGINEERING

Biosystems Engineering

Pub Date : 2024-11-01 DOI: 10.1016/j.biosystemseng.2024.10.009

Peng Zhang , Xiongye Zhang , Xue Hu , Lixin Zhang , Xuebin Shi , Zhigang Li

Plough blades are widely used for land preparation tasks such as rotary tillage and trenching in small farmlands. This paper, using the finite element method, establishes a dynamic simulation model for plough blade cutting through soil. Utilising simulation and experimental data, the study inversely determined a constant value of K = 1.71 × 10⁻⁵ for the wear formula and developed an Archard wear mathematical model applicable to predicting plough blade wear during soil cutting. Subsequently, a Python script was developed for extracting data during the plough blade cutting process. The UMESHMOTION subroutine, combined with the ALE grid remeshing method, was then employed to simulate the wear morphology of the plough blade tip. A comprehensive numerical analysis of wear is conducted over time intervals of 2 h, 3.5 h, 5 h, and 6 h. The results indicated that the maximum wear occurred at the junction between the rear blade surface and the plough blade tip, with corresponding maximum wear amounts of 1.887 mm, 2.750 mm, 3.766 mm, and 4.359 mm. Comparison with actual wear conditions during the operation of a micro-tiller suggests that, within the same wear stage of the blade, the proposed wear numerical analysis method effectively simulated the wear amount during plough blade soil cutting. Furthermore, a comparison of wear amounts under different operational parameters showed that an increase in forward speed led to wear amount increments of 26.62 % and 35.23 %, while an increase in rotational speed resulted in wear amount increments of 17.77 % and 43.88 %. Both factors significantly impact plough blade wear.

犁刀广泛用于小型农田的旋耕和开沟等整地作业。本文采用有限元法建立了犁刀切割土壤的动态模拟模型。利用模拟和实验数据，该研究反向确定了磨损公式的常数 K = 1.71 × 10-5，并建立了适用于预测土壤切割过程中犁刃磨损的 Archard 磨损数学模型。随后，还开发了一个 Python 脚本，用于提取犁刀切割过程中的数据。然后采用 UMESHMOTION 子程序，结合 ALE 网格重网格法，模拟犁刀刀尖的磨损形态。结果表明，最大磨损发生在后刀面与犁刀尖的交界处，相应的最大磨损量分别为 1.887 毫米、2.750 毫米、3.766 毫米和 4.359 毫米。与微耕机工作时的实际磨损情况比较表明，在刀片的同一磨损阶段，所提出的磨损数值分析方法有效地模拟了犁刀切土过程中的磨损量。此外，对不同运行参数下的磨损量进行的比较表明，前进速度的增加导致磨损量分别增加 26.62 % 和 35.23 %，而旋转速度的增加导致磨损量分别增加 17.77 % 和 43.88 %。这两个因素都会对犁刀磨损产生重大影响。

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引用次数: 0

Harvest motion planning for mango picking robot based on improved RRT-Connect 基于改进型 RRT-Connect 的芒果采摘机器人收获运动规划

IF 4.4 1区农林科学 Q1 AGRICULTURAL ENGINEERING

Biosystems Engineering

Pub Date : 2024-10-29 DOI: 10.1016/j.biosystemseng.2024.10.008

Bin Zhang , Chenghai Yin , Yuxing Fu , Yuyang Xia , Wei Fu

Aiming at the problems of long motion path planning time and low picking efficiency of picking robots in unstructured orchard environments, a heuristic dynamic Rapidly-exploring Random Tree Connect motion planning algorithm (HDRRT-Connect) for picking robots for fast mango harvesting path planning was proposed in this study. The algorithm was obtained by introducing adaptive target gravitation strategy and heuristic dynamic step strategy based on RRT-Connect algorithm. It adjusts the step-size according to the information of the orchard environment as well as the path searching situation, so as to avoid falling into the local optimum of the path. The prototype based on the algorithm was used to carry out picking experiments in the natural orchard environment. The prototype picking test under the natural environment of the orchard is carried out, and the test results showed that the average path cost of the HDRRT-Connect algorithm was 95.7739, the average planning time was 0.448 s, and the success rate was 90%. Compared with the RRT, RRT-Connect and Probabilistic Roadmaps (PRM) algorithms, the HDRRT-Connect planning speed was improved by 95%, 24% and 59%, respectively, and the path cost was reduced by 35%, 13% and 18%, respectively. The results of the experiment verified the feasibility and efficiency of the improved algorithm. The HDRRT-Connect algorithm proposed in this study could effectively shorten the planning time, reduce the search path cost and improve the planning success rate. The research provides technical support for the fast-harvesting operation of mango picking robot.

针对采摘机器人在非结构化果园环境中运动路径规划时间长、采摘效率低的问题，本研究提出了一种启发式动态快速探索随机树连接运动规划算法（HDRRT-Connect），用于采摘机器人快速采摘芒果的路径规划。该算法在 RRT-Connect 算法的基础上引入了自适应目标重力策略和启发式动态步长策略。它根据果园环境信息和路径搜索情况调整步长，以避免陷入路径的局部最优。基于该算法的原型在自然果园环境中进行了采摘试验。进行了果园自然环境下的原型采摘试验，试验结果表明，HDRRT-Connect 算法的平均路径代价为 95.7739，平均规划时间为 0.448 s，成功率为 90%。与 RRT、RRT-Connect 和概率路线图（PRM）算法相比，HDRRT-Connect 规划速度分别提高了 95%、24% 和 59%，路径成本分别降低了 35%、13% 和 18%。实验结果验证了改进算法的可行性和高效性。本研究提出的 HDRRT-Connect 算法能有效缩短规划时间，降低搜索路径成本，提高规划成功率。该研究为芒果采摘机器人的快速采摘作业提供了技术支持。

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引用次数: 0

Enhancing hydraulic efficiency in jet impingement sprinklers: Comparative analysis of aperture ratios compared with non-impingement sprinklers 提高喷射冲击式洒水器的水力效率：孔径比与非撞击式喷洒器的比较分析

IF 4.4 1区农林科学 Q1 AGRICULTURAL ENGINEERING

Biosystems Engineering

Pub Date : 2024-10-28 DOI: 10.1016/j.biosystemseng.2024.10.004

Zixin Wang , Yue Jiang , Hong Li , Lisha Wang

A jet impingement sprinkler was designed based on asymmetric collision between the primary and secondary jets to replace traditional rotating sprinklers that require additional water distribution devices to provide suitable water distribution at low pressures. The study focuses on the ratio of apertures between primary and secondary nozzles, deriving a theoretical relationship based on jet momentum. The factors contributing to the variation in hydraulic performance between jet-impingement and non-impinging sprinklers are elucidated by combining hydraulic performance experiments with experiments using high-speed photography (HSP). The results show that the developed jet impingement sprinkler achieved a smoother water distribution trend. The wetted radius and Christiansen's uniformity coefficient of the jet impingement sprinkler were evaluated using the Criteria Importance via the Intercriteria Correlation (CRITIC) method. A comparison of the average scores shows that an aperture ratio of 1.66 performs best under full pressure. By contrast, an aperture ratio of 1.33 exhibited superior performance at low pressure. Jet deflection angle and jet breakup length were obtained through HSP experiments. The relative error between the measured and theoretical jet deflection angles was less than 5%, demonstrating the reliability of the proposed theoretical calculation method. A non-linear curve was used to establish the relationship among the aperture ratio, diameter of the primary nozzle exit, jet breakup length, average measured jet deflection angle, working pressure, and wetted radius. The relative error between the calculated and measured values was within 4%, indicating the suitability of the new formula for calculating the wetted radius of jet impingement sprinklers.

设计了一种基于主喷嘴和副喷嘴之间不对称碰撞的喷射撞击喷头，以取代传统的旋转喷头，后者需要额外的配水装置才能在低压下提供合适的配水。研究重点是主喷嘴和副喷嘴之间的孔径比，并根据喷射动量推导出理论关系。通过将水力性能实验与高速摄影（HSP）实验相结合，阐明了造成喷射撞击喷头与非撞击喷头之间水力性能差异的因素。结果表明，开发的喷射撞击式喷灌机实现了更平滑的水流分布趋势。采用标准重要性与标准间相关性（CRITIC）方法对喷射撞击式喷灌机的润湿半径和克里斯琴森均匀系数进行了评估。对平均得分的比较表明，在全压条件下，孔径比为 1.66 的喷头性能最佳。相比之下，1.33 的孔径比在低压下表现更佳。喷射偏转角和喷射破裂长度是通过 HSP 实验获得的。测量和理论射流偏转角之间的相对误差小于 5%，证明了所提出的理论计算方法的可靠性。利用非线性曲线确定了孔径比、主喷嘴出口直径、射流破裂长度、平均测量射流偏转角、工作压力和润湿半径之间的关系。计算值和测量值之间的相对误差在 4% 以内，表明新公式适用于计算喷射撞击式喷头的润湿半径。

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引用次数: 0

Verifying the reliability of CFD domain decomposition technique on modelling the airflow field inside a naturally ventilated cattle barn 验证 CFD 域分解技术对自然通风牛舍内气流场建模的可靠性

IF 4.4 1区农林科学 Q1 AGRICULTURAL ENGINEERING

Biosystems Engineering

Pub Date : 2024-10-24 DOI: 10.1016/j.biosystemseng.2024.10.001

Guoxing Chen, Guoqiang Zhang, Li Rong

Conventionally, the airflow fields outside and inside the naturally ventilated livestock buildings are modelled simultaneously in one computational domain using CFD (Computational Fluid Dynamics). The presence of surrounding buildings, indoor facilities and animals for large scale cattle barns make the required computational power extremely high and even unfordable to achieve simulation results with reasonable accuracy. The Domain Decomposition Technique (DDT), dividing simulations into two separate steps, is an alternative CFD framework to provide sufficient accuracy with affordable computations at each step. The objective of this study was to verify the reliability of DDT on modelling the airflow fields inside a naturally ventilated cattle barn (NVCB) by employing wind tunnel measurements. The exterior airflow fields around the targeted NVCB, which was opened with varying opening ratios, were first simulated to obtain the airflow boundary conditions at sidewall openings by applying exterior wind conditions at the inlet of the computational domain. The interior airflow of the targeted NVCB, were secondly simulated by applying the achieved airflow boundary conditions at sidewall openings from the first step simulation. The interior airflow fields obtained by DDT were in good agreement with wind tunnel measurements. This indicates that DDT can provide an alternative for CFD application in large-scale NVCB with presence of surrounding buildings, indoor facilities and animals, though these had not been considered in this study.

传统上，自然通风牲畜建筑内外的气流场是在一个计算域中使用 CFD（计算流体动力学）同时建模的。由于大型牛舍周围建筑物、室内设施和动物的存在，所需的计算能力极高，甚至无法获得具有合理精度的模拟结果。域分解技术（DDT）将模拟分为两个独立的步骤，是一种可供选择的 CFD 框架，可在每个步骤中以可承受的计算量提供足够的精度。本研究的目的是通过风洞测量，验证 DDT 对自然通风牛舍（NVCB）内部气流场建模的可靠性。首先模拟了以不同开口率打开的目标牛舍周围的外部气流场，通过在计算域入口处应用外部风力条件，获得了侧壁开口处的气流边界条件。然后，应用第一步模拟中获得的侧壁开口处气流边界条件，模拟目标 NVCB 的内部气流。DDT 得出的内部气流场与风洞测量结果非常吻合。这表明 DDT 可作为 CFD 应用于周围有建筑物、室内设施和动物（本研究未考虑这些因素）的大型非易燃易爆场所的替代方法。

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引用次数: 0