Modeling and Kinematics Simulation of Hydro-mechanical Split Path Steering Device of Tracked Vehicle Based on CATIA

Based on the working principle of hydro-mechanical split path of tracked vehicle, a operating gear was developed which was controlled by steering wheel and match with transmission case. Then CATIA software was used to build the three-dimensional model and carry out dynamic simulation of the mechanism. The result indicates that the design of the mechanism fulfills the request.     

果树仿形喷雾的虚拟研究

鉴于很多研究者只通过试验来定性地研究各种过程参量对喷雾质量的影响,为此作者基于已有的实际试验数据,提出了从理论上对喷雾进行虚拟研究,构建三维空间中的喷雾数学模型,实现了虚拟系统,并对虚拟的结果与实际数据进行分析和对比。结果表明,喷雾过程是一个非常复杂而且难以描述的过程。模型能虚拟实际中雾滴在果树中的飞行情况,能够反映实际喷雾的关键元素,可以仿真喷雾沉积分布的趋势。虚拟喷雾模型中设置不同的喷嘴高度,得到的沉积率的趋势一样,说明喷雾高度的变化对结果没有太大的影响。喷雾模型可对开发果树仿形喷雾预测系统或产品提供一定的理论支持。     

基于GIS的塔里木河下游地下水定量回归模拟研究

对于干旱区内陆河流域来说,地下水埋深是指示当地生态变化的至关重要的因子。本文以新疆塔里木河下游为例,基于少量的监测井监测数据,尝试利用分类分段横向和纵向联合回归分析方法模拟地下水位空间分布变化,以1:1万DEM为基础数据运用GIS技术实现数字地下水埋深空间化。结合生态监测井实时监测数据以及地下水分布与植被的响应关系进行模拟精度分析,表明该模拟方法在地下水位监测数据较少和水文地质条件相对单一的干旱区内陆河具有一定的可行性。     

ASAS-NANP Symposium: Mathematical Modeling in Animal Nutrition: The progression of data analytics and artificial intelligence in support of sustainable development in animal science

A renewed interest in data analytics and decision support systems in developing automated computer systems is facilitating the emergence of hybrid intelligent systems by combining artificial intelligence (AI) algorithms with classical modeling paradigms such as mechanistic modeling (HIMM) and agent-based models (iABM). Data analytics have evolved remarkably, and the scientific community may not yet fully grasp the power and limitations of some tools. Existing statistical assumptions might need to be re-assessed to provide a more thorough competitive advantage in animal production systems towards sustainability. This paper discussed the evolution of data analytics from a competitive advantage perspective within academia and illustrated the combination of different advanced technological systems in developing HIMM. The progress of analytical tools was divided into three stages: collect and respond, predict and prescribe, and smart learning and policy making, depending on the level of their sophistication (simple to complicated analysis). The collect and respond stage is responsible for ensuring the data is correct and free of influential data points, and it represents the data and information phases for which data are cataloged and organized. The predict and prescribe stage results in gained knowledge from the data and comprises most predictive modeling paradigms, and optimization and risk assessment tools are used to prescribe future decision-making opportunities. The third stage aims to apply the information obtained in the previous stages to foment knowledge and use it for rational decisions. This stage represents the pinnacle of acquired knowledge that leads to wisdom, and AI technology is intrinsic. Although still incipient, HIMM and iABM form the forthcoming stage of competitive advantage. HIMM may not increase our ability to understand the underlying mechanisms controlling the outcomes of a system, but it may increase the predictive ability of existing models by helping the analyst explain more of the data variation. The scientific community still has some issues to be resolved, including the lack of transparency and reporting of AI that might limit code reproducibility. It might be prudent for the scientific community to avoid the shiny object syndrome (i.e., AI) and look beyond the current knowledge to understand the mechanisms that might improve productivity and efficiency to lead agriculture towards sustainable and responsible achievements.     

Integrated modeling environment for statewide assessment of groundwater vulnerability from pesticide use in agriculture

Atrazine, a herbicide widely used for corn production in the Midwest, has been detected in groundwater of several states, and has been identified as a possible human carcinogen. With the widespread use of pesticides in crop production, and the frequent detection of these chemicals in groundwater, large-scale risk assessments would help water resource managers to identify areas that are more susceptible to contamination and implement practices to ameliorate the problem. This paper presents an integrated, visual and interactive system for predicting potential environmental risks associated with pesticide contamination at spatial scales ranging from fields to landscapes and regions. The interactive system extends the predictive ability of the Pesticide Root Zone Model Release 2.0 (PRZM-2) to a landscape and statewide scale through integration with a geographic information system (GIS), graphical user interface and environmental databases. Predictions of statewide (Iowa) vulnerability of groundwater from atrazine leaching below the unsaturated zone were made to demonstrate the utility of the system, and the results were used in risk assessment. In the example application, atrazine fate and transport were evaluated using long-term climatic data (1980--1989) in combination with several environmental databases (eg STATSGO soils database) and exposure risks were expressed in terms of the probability of the predicted pesticide concentrations exceeding the maximum contaminant level (MCL) for drinking water. The results indicate that the predicted pesticide concentrations were significantly lower than the EPA-established MCL. In addition to providing an interactive environment for landscape-level assessment of potential risks from pesticide leaching, the system significantly reduces the time and resources needed to organize and manipulate data for use with PRZM-2, and provides an analytical framework for evaluating groundwater-leaching impacts of pesticide management practices.     

入侵害虫松树蜂气味结合蛋白与其相关信息化学物质的分子对接

为探究入侵我国的重大林业检疫性害虫松树蜂Sirex noctilio的气味结合蛋白(odorant binding protein,OBP)与其相关信息化学物质的结合模式和结合能力,采用Swiss-model在线服务器对松树蜂触角中高表达的4种OBP序列进行同源模建,采用Procheck、Verify_3D和ERRAT程序对模建质量进行评价;并应用Autodock软件对OBP模型和相关信息化学物质进行分子对接分析。结果显示,在松树蜂触角中高表达的4种蛋白为SnocOBP4、SnocOBP6、SnocOBP9和SnocOBP12,其同源模建所得模型质量较好:均满足拉氏构象图中氨基酸位于最佳合理区的数量大于90%的条件;三维结构与一级结构的兼容性评分大于0.2;所得ERRAT值分别为85.71%、95.10%、98.15%和91.82%。分子对接显示,与松树挥发物α-蒎烯和β-蒎烯结合最好的蛋白是SnocOBP12,结合能分别为-5.36 kJ/mol和-5.48 kJ/mol;与雌性信息素成分顺-9-二十九烯结合最好的蛋白是SnocOBP4,结合能为-5.42 kJ/mol;与雄性信息素成分顺-3-癸烯醇和顺-4-癸烯醇结合最好的蛋白是SnocOBP9,结合能分别为-4.37 kJ/mol和-4.45 k J/mol;而3-蒈烯、顺-7-二十七烯和反-2,4-癸二烯醛等气味分子与SnocOBP6的结合能较低,结合能最低的是顺-7-二十七烯,为-6.08 k J/mol。雄蜂主要信息素成分顺-3-癸烯醇与其同分异构体反-3-癸烯醇相比,与SnocOBP9的结合能较低;但是反-3-癸烯醇能以较强的氢键竞争SnocOBP9结合位点。研究表明这4种松树蜂OBP与相应植物挥发物或雌雄信息素具有较好的亲和力,参与了松树蜂对不同信息化学物质的识别过程。     

基于ArcScene三维数字流域建模研究

三维数字流域是对流域周边地理环境、自然环境和生态环境等各种信息的直观显示,对流域内经济建设与资源利用有重要的辅助作用.该研究提出了一种基于ArcScene的三维数字流域建模方法.利用航空摄影测量获得的高分辨率的DOM影像与DEM数据进行叠加分析,实现了数字流域的建模与多视图的三维飞行动画预览.利用该方法可以对流域内地形地貌与人文特征进行快速直观的预览与分析,为流域内水利设施、交通设施、社会公共设施的设计施工与改建的顺利进行提供重要的技术支持.     

从连续的粒径大小分布数据估算土壤水分特征曲线

Soil moisture characteristic curve (SMC) is a fundamental soil property and its direct measurement is tedious and time consuming. Therefore, various indirect methods have been developed to predict SMC from particle-size distribution (PSD). However, the majority of these methods often yield intermittent SMC data because they involve estimating individual SMC points. The objectives of this study were 1) to develop a procedure to predict continuous SMC from a limited number of experimental PSD data points and 2) to evaluate model predictions through comparisons with measured values. In this study, an approach that allowed predicting SMC from the knowledge of PSD, parameterized by means of the closed-form van Genuchten model (VG), was used. Through using Mohammadi and Vanclooster (MV) model, the parameters obtained from fitting of VG to PSD data were applied to predict SMC curves. Since the residual water content (θ r ) could not be obtained through fitting of VG-MV integrated model to PSD data, we also examined and compared four different methods estimating θ r . Results showed that the proposed equation (MV-VG integrated model) provided an excellent fit to all the PSD data and the model could adequately predict SMC as measured in forty-two soils sampled from different regions of Iran. For all soils, the method in which θ r was obtained through parameter optimization procedure provided the best overall predictions of SMC. The two methods estimating θ r with Campbell and Shiozawa (CS) model resulted in less accuracy than the optimization procedure. Furthermore, the proposed model underestimated the moisture content in the dry range of SMC when the value of θ r was assumed to equal zero. θ r could be attributed to the incomplete desorption of water coated on soil particles and the accurate estimation of θ r was critical in prediction of SMC, especially for fine-textured soils at high suction heads. It could be concluded that the advantages of our approach were the continuity, robustness, and independency of model performance on soil type, allowing to improve predictions of SMC from PSD at the field and watershed scales.     

A cell-based reporter assay for screening for EcR agonist/antagonist activity of natural ecdysteroids in Lepidoptera (Bm5) and Diptera (S2) cell cultures,followed by modeling of ecdysteroid-EcR interactions and normal mode analysis

Ecdysteroid signal transduction is a key process in insect development and therefore an important target for insecticide development. We employed an in vitro cell-based reporter bioassay for the screening of potential ecdysone receptor (EcR) agonistic and antagonistic compounds. Natural ecdysteroids were assayed with ecdysteroid-responsive cell line cultures that were transiently transfected with the reporter plasmid ERE-b.act.luc. We used the dipteran Schneider S2 cells of Drosophila melanogaster and the lepidopteran Bm5 cells of Bombyx mori, representing important pest insects in medicine and agriculture. Measurements showed an EcR agonistic activity only for cyasterone both in S2 (EC₅₀ = 3.3 μM) and Bm5 cells (EC₅₀ = 5.3 μM), which was low compared to that of the commercial dibenzoylhydrazine-based insecticide tebufenozide (EC₅₀ = 0.71 μM and 0.00089 μM, respectively). Interestingly, a strong antagonistic activity was found for castasterone in S2 cells with an IC₅₀ of 0.039 μM; in Bm5 cells this effect only became visible at much higher concentrations (IC₅₀ = 18 μM). To gain more insight in the EcR interaction, three-dimensional modeling of dipteran and lepidopteran EcR-LBD was performed. In conclusion, we showed that the EcR cell-based reporter bioassay tested here is a useful and practical tool for the screening of candidate EcR agonists and antagonists. The docking experiments as well as the normal mode analysis provided evidence that the antagonist activity of castasterone may be through direct binding with the receptor with specific changes in protein flexibility. The search for new ecdysteroid-like compounds may be particularly relevant for dipterans because the activity of dibenzoylhydrazines appears to be correlated with an extension of the EcR-LBD binding pocket that is prominent in lepidopteran receptors but less so in the modeled dipteran structure.