A Solid Modeling and Geometric Analysis of Hourglass Worm Gearing     

Qin Dongxing Qin Datong Shi Wankai 《保鲜与加工》1998,(4):79-83

Based on the theory of conjugate surface and computer graphics, a solid modeling method of hourglass worm gearing is presented. Assembly simulation of worm gearing is carried out, clearance and interference between meshing tooth surfaces are analyzed, and effects of machining and modification of assembling parameters on meshing and contact between tooth surfaces are investigated.  相似文献   

Does pattern matter? Exploring the pathways and effects of urban green space on promoting life satisfaction through reducing air pollution     

《Urban Forestry & Urban Greening》2023

Urban green space is widely acknowledged to promote public health through multiple pathways. However, there is limited understanding of how the spatial patterns of green space might play different roles in such a process. This study examined potential pathways through which spatial patterns of green space improved people’s life satisfaction (LS) by reducing air pollution. A partial least squares structural equation model was adopted to explore these pathways in sampled urban areas (township) of China (n = 60). Green space spatial patterns were measured using landscape metrics of size, aggregation, fragmentation, and diversity. The results did not show that green space spatial pattern promoted LS by reducing air pollution. However, green space size and fragmentation were negatively associated with air pollution (mainly PM 2.5, PM 10, and NO 2). The pattern of highly densely distributed small green spaces was related to higher LS, as was high diversity of green space type. Simply adopting a fragmented green space pattern to reduce air pollution might be simultaneously associated with reduced LS. This alerts decision-makers and planners to the potential “double-edged sword” effect of optimizing green space structures to improve air quality, which may not yield strongly favorable results due to the impacts that hinder LS.  相似文献   

Drying Kinetics and Quality Characteristics of Indian Mackerel (Rastrelliger kanagurta) in Solar–Electrical Hybrid Dryer     

S. Murali  K. Sathish Kumar  P. V. Alfiya  D. S. Aniesrani Delfiya  Manoj P. Samuel 《Journal Of Aquatic Food Product Technology》2019,28(5):541-554

The aim of the study was to investigate the drying kinetics and quality characteristics of Indian mackerel dried under solar–electrical hybrid dryer (S-EHD). Fresh Indian mackerel fishes (Rastrelliger kanagurta) were cleaned, cut into butterfly fillets, and salted overnight using a dry salting method (salt-to-fish ratio, 1:3). The salted mackerel was dried in a S-EHD at the air temperature of 45–55°C, relative humidity of 47–62%, and air velocity of 0.60–0.80 m/s. Open sun drying (OSD) of salted Indian mackerel was conducted to compare with S-EHD. The moisture content of the salted mackerel (61.5% w.b.) was reduced to 31.8% (w.b.) under S-EHD and 30.25% (w.b) under OSD in 8 and 32 h, respectively. The drying rate curve showed that mackerel drying occurred under falling-rate drying period in both the drying methods. A drying efficiency of 23.81% was observed for salted Indian mackerel drying under S-EHD. Diffusion approach and two-term models were selected to accurately predict the drying behavior of mackerel under S-EHD and OSD, respectively. Total volatile base nitrogen (TVB-N), trimethylamine, and thiobarbituric acid analysis of dried samples revealed that the mackerel dried under S-EHD was better than OSD. In the sensory analysis, samples dried under S-EHD recorded highest overall acceptability score.  相似文献   

基于逆向设计的连杆零件三维建模与制造     

冯超超 《农业装备与车辆工程》2020,58(2):119-122

以发动机上的连杆零件为对象进行逆向设计,主要是研究逆向技术如何对连杆进行反求,利用逆向技术实现连杆制造的过程。通过对现有实体模型数据采集、点云处理,然后利用软件在其基础上建立模型,再在模型基础上设计加工程序输入数控机床加工模型,从而实现对现有模型的反求。  相似文献   

Inverse modeling of laboratory experiment to assess parameter transferability of pesticide environmental fate into outdoor experiments under paddy test systems     

Kei Kondo  Yoshiki Wakasone  Kazuaki Iijima  Kazutoshi Ohyama 《Pest management science》2020,76(8):2768-2780

  相似文献   

Canopy spray deposition and related mortality impacts of commonly used insecticides on Drosophila suzukii Matsumura (Diptera: Drosophilidae) populations in blueberry     

Serhan Mermer  Ferdinand Pfab  Gwen A Hoheisel  Haitham Y Bahlol  Lav Khot  Daniel T Dalton  Linda J Brewer  Marco V Rossi Stacconi  Chengzhu Zhang  Lan Xue  Vaughn M Walton 《Pest management science》2020,76(4):1531-1540

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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   总被引：1，自引：0，他引：1  

郭冰  郝恩华  王菁桢  陆鹏飞  乔海莉 《植物保护学报》2019,46(5):1004-1017

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。  相似文献   

BIM技术在Venlo温室设计中的应用分析     

张勇  陈瑜  朱晓红  许良鹤  张柯新  邹志荣 《农业工程学报》2021,37(20):256-265

针对现行大型温室设计过程中普遍存在的设计工作流中信息不连贯、多平台重复建模、修改图纸工作量大且易出错以及预算工程量主要依靠人工提取等问题,提出一种基于BIM（Building Information Modeling）技术的大型温室设计方法和工作流。依托BIM技术在建筑领域的应用,有机结合高科技温室的设计工作需求,以Venlo温室为例,研究了设计阶段应用BIM技术的系统方法,明确了不同功能软件之间的信息交互模式,构建了基于BIM技术,以Revit为核心的Venlo温室设计、分析、出图和造价分析全体系工作流程,创建了基于中国温室技术特点的Venlo温室BIM族库。实现了从场地形体方案筛选、主体模型搭建、流场分析、结构分析、节点深化、各系统安装及综合检查、图纸明细表生成和效果图制作等全流程的BIM工作流体系搭建。研究结果表明,尽管BIM设计方法需在模型创建阶段投入相对较多时间,但分析工作可以基于BIM模型快速流畅进行,图纸可以借助软件在碰撞检查后快速创建,特别是在设计优化时可以快速地完成图纸的系统修改和完善,显著减少了重复绘图时间工作量,整体上可以较现行设计方法设计效率提升30%。将BIM技术应用在Venlo温室设计中,可以优化设计流程,加强对项目信息的管理和应用,提高项目设计效率和效益,对设施园艺产业的高质量发展有积极意义。  相似文献   

稻田-沟塘系统水氮动态模拟与灌排调控模型构建   总被引：1，自引：1，他引：0  

梁浩  胡宗荟  杨士红  徐俊增  顾哲  胡克林 《农业工程学报》2021,37(22):49-57

沟塘系统对农田排水具有较好的拦蓄能力,是降低中国南方稻区农业面源污染风险的有效措施,定量化评价稻田-沟塘系统水氮过程是合理制定水氮管理措施的关键。该研究以稻田-作物模型WHCNS_Rice为基础,通过添加沟塘水氮平衡和灌排调控过程,构建了稻田-沟塘系统水氮调控模型。并采用太湖流域2 a不同灌排和施肥处理的田间试验数据校准和验证模型,分析不同灌排和施肥处理下稻田-沟塘系统的调控策略。研究结果显示,模型能够模拟不同灌排和施肥处理下稻田土壤含水量、稻田田面水深、径流量、氮素径流损失量、氨挥发量、作物吸氮量和作物产量,模拟的相对均方根误差、一致性指数和模型模拟效率的范围分别为4.6%～29.7%、0.758～0.996和0.073～0.983,均在可接受的范围内。模拟结果显示,与传统处理相比,控制灌溉结合优化施肥,减少了稻田32.1%～36.2%的灌溉水用量和36.7%～67.3%的氮素径流损失,同时平均降低了55.1%沟塘硝态氮浓度,从而降低了沟塘地表氮素径流损失风险。Morris敏感度分析结果显示,稻田土壤水力学参数和沟塘渗漏速率对沟塘水深的模拟影响较大,而作物参数的敏感度相对较低。沟塘硝态氮浓度对稻田水力学参数、沟塘氮素消纳系数和氨挥发一阶动力学系数较敏感。同时,构建的模型能反映不同水氮管理措施和沟塘/稻田面积比下稻田-沟塘系统水分消耗、氮素去向和作物生长过程。该模型可为优化稻田-沟塘系统水氮管理方案、防控农业面源污染提供有力工具。  相似文献   

基于Smart3D无人机倾斜摄影三维建模方法研究     

牛磊  谭文辉  邱健壮  张峰 《中国农业信息》2021,(5):59-66

[目的]无人机倾斜摄影三维建模具有低成本、高效率和精度高等优点,成为实景三维建模的主流方法,进一步提高大范围实景三维建模效率和精细度,可为实景三维中国建设提供数据支撑和技术支持.[方法]文章以山东省泰安市岱岳经济开发区为研究区,借助哈瓦无人机获取倾斜摄影测量数据,通过Smart3D软件构建实景三维模型,并提出了针对研究...  相似文献