基于恒压变流控制的变量喷雾试验研究

针对变量喷雾过程中引起压力变化的问题,为研究其中压力稳定性现象,利用PID恒压控制和PWM变流控制相结合的方法,建立了恒压变流喷雾试验台。在试验台上进行恒压控制试验、喷雾角测量和雾量分布测量试验,从而验证所搭建的恒压变流喷雾装置的恒压稳定性。结果表明:在喷雾流量发生变化时,试验装置能使喷头的喷雾角和雾量分布稳定在固定范围内。     

自然保护地环境教育实践与研究现状

环境教育是多学科融合的激发人们环境保护意识、培养正确环境价值观的教育。国际上自然保护地环境教育研究主要集中在环境教育内容和形式、环境教育效果评价及其影响因素分析、环境教育监测和法律体系完善等领域。在实践方面，环境教育内容和形式不断丰富，出现相对多样化的环境教育模式和较为健全的环境教育评价与法治管理体系。典型的有美国黄石公园设置的少年巡逻员岗位项目、英国的野外环境教育培训基地和日本的生态自然体验露营地等。我国自然保护地环境教育研究关注了国外相关理论与实践，侧重于从宏观层面对我国环境教育提出原则性、策略性的建议等。文中在分析国际自然保护地环境教育研究与实践的基础上，结合我国自然保护地环境教育现状及存在的问题，提出了完善环境教育内容和形式、建立健全环境教育评价和法律体系等发展建议。     

长三角地区某市垃圾焚烧行业环保现状调查研究

对长三角地区某市垃圾焚烧行业的环保现状进行了调查研究,结果发现:当前区域垃圾焚烧企业,在保证规模、控制数量及地域上均衡布置的前提下,行业废水、废气污染治理设施齐全,废水、废气均稳定可达标排放,调查时段内未有投诉问题。区域垃圾焚烧行业在做到当下要求的情况下,实现了区域垃圾焚烧行业污染可控,对城市垃圾焚烧行业环保发展具备借鉴意义。     

基于物联网的玉米病害环境监测系统研究与实现

为研究和实现基于物联网的玉米病害环境监测系统,笔者设计了包括感知层、传输层、云服务层和应用层的4层架构。在感知层,利用传感器技术实时采集玉米病害环境的温湿度、降雨量、风向风速、光照强度和土壤温湿度等数据;在传输层中使用4G移动通信网络实现数据的远距离传输;云服务层中,基于四川农畜育种攻关云服务平台,应用数据库技术、云服务技术实现数据的存储和管理;最后,在应用层采用B/S模式实现数据展示服务。结果表明,该系统能够准确采集、稳定传输和安全存储数据,降低了人工成本。因此,它能够为玉米病害研究课题组提供有效的信息化服务,具有一定实用价值。     

基于玻璃化转变的稻谷变温热风干燥工艺研究

为保证稻谷干燥后品质、提高干燥效率,基于不同含水率稻谷的玻璃化转变温度,提出变温热风干燥工艺。采用三因素五水平中心组合试验方法,以稻谷温度、初始含水率和热风风速为影响因素,以稻谷爆腰指数、整精米率和干燥时间为评价指标,研究稻谷玻璃化转变温度、恒温和变温干燥特性,模拟解析稻谷干燥过程中传热传质规律,以5、10、15℃的变温幅度进行变温干燥试验。结果表明,稻谷玻璃化转变温度与其含水率呈负相关,恒温干燥最佳工艺参数为稻谷温度47℃、初始含水率22.0%、热风风速0.50 m/s,干燥后稻谷爆腰指数70、整精米率57.67%、干燥时间195 min;与恒温干燥相比,以5℃和10℃为变温幅度的变温干燥工艺,干燥后稻谷爆腰指数分别降低了20和10,整精米率提高12.6、7.7个百分点,干燥时间缩短30 min和60 min。研究表明,基于玻璃化转变的稻谷变温热风干燥工艺明显改善了稻谷干燥后品质,提高了干燥效率。     

果园有机肥深施机分层变量排肥控制系统设计与试验

果园不同深度的土壤养分不同，果树根系分层吸肥能力不同，有机肥分层变量深施可以解决传统施肥存在的养分分布不均和肥料利用率低等问题。针对有机肥分层变量深施的排肥控制问题，本文设计了排肥控制系统，可以根据用户设置的各层理论排肥量和作业速度，实时计算液压马达的理论转速，并采用PID算法控制比例流量阀开度，调节马达转速驱动螺旋输送器排肥，实现分层变量排肥。将AMESim中建立的液压系统模型与在Matlab/Simulink中建立的控制模型进行联合仿真，整定PID参数。液压马达转速调节性能试验中最大超调量为14r/min，达到稳定转速的时间最大为6s，控制性能较好，表明通过AMESim-Matlab/Simulink联合仿真，能够快速便捷地整定PID参数，结果准确可靠。排肥控制性能试验中排肥量相对误差最大6.20%，变异系数最大8.69%，排肥量准确性和均匀性均达到要求。设计的控制系统具有较好的性能，能为果园有机肥分层变量深施提供技术支撑。     

二十二份毛花猕猴桃种质资源果实品质的主成分分析与综合评价

为了更好地了解毛花猕猴桃种质资源的多样性,测定了浙江省丽水市境内22份毛花猕猴桃种质的8个品质指标,进行了变异分析、主成分分析、聚类分析和综合评价。结果表明,果实品质指标差异较大,单果质量的变异系数最大(38%);果实横径的变异系数最小(11%);聚类分析结果表明,22份毛花猕猴桃种质可以分为两大类,其中第一类种质果实的可溶性固形物含量、可滴定酸含量、维生素C含量均高于第二类,第二类种质果实的固酸比稍高于第一类;主成分分析表明,前三个主成分贡献率达85.04%,可综合反映果实品质信息;综合评价结果显示,LD-18、L-74、L-27、L-19、L-73这5个单株果实综合性状表现优良。综上所述,丽水市境内毛花猕猴桃种质资源果实性状具有丰富的多样性,为新品种的选育和果实品质改良提供了重要的参考依据。     

植保机变量施药鲁棒H∞最优控制

提出了一种基于电控伺服变量柱塞泵的植保机变量施药控制方法,推导并建立了包含参数不确定性和扰动的施药流量模型,设计了鲁棒H∞最优控制器并证明其鲁棒稳定性,并转化为线性矩阵不等式求解控制器参数。本研究弥补了传统优化控制方法对于不确定性反应较为敏感的不足,与传统的线性二次型最优控制相比具有一定的快速性和鲁棒性优势,能够满足复杂作业条件下植保机精准变量施药要求,有效提高了农药利用率。     

Body shape variation in two species of darters (Etheostoma,Percidae) and its relation to the environment

Environmental variation can shape phenotypic variation in organisms, but most evidence for trait differentiation comes from analyses of dichotomous habitat types that differ in only one or few key environmental factors. In reality, environmental variation is often more subtle, gradual and multifarious. Here, we investigated geographic variation in body shape of two darter species (Etheostoma spectabile and Etheostoma flabellare; Percidae) that occur along river gradients. This study addressed three specific questions: Is there intraspecific geographic variation in the two species across different sites in the Ozark Highlands of Oklahoma (USA)? Is phenotypic variation across sites correlated with abiotic environmental conditions? Do the two species share site‐specific (i.e. convergent) phenotypic variation in areas where they occur together? Our results indicated significant body shape variation in both species. Population differences in body shape were particularly correlated with variation in substrate composition. The combined analysis of both species indicated a small but significant effect of convergence on body shape wherever they are sympatric; shared variation, however, was not related to any environmental variables included in the analysis. While it remains unclear whether phenotypic variation in these species is due to heritable differentiation or environmentally induced plasticity, our results indicate that even subtle and gradual environmental variation can induce substantial variation in phenotypes on a relatively small spatial scale.     

A comparison of changes in stable isotope ratios in the epidermal mucus and muscle tissue of slow‐growing adult catfish

Although stable isotope analysis is a powerful tool for determining diet, migration patterns and the structure of food webs in aquatic systems, the slow response of isotopic ratios in the widely used muscle tissue often hampers this approach, particularly in slow‐growing or adult fishes. We conducted a diet‐switch experiment to compare the changes in the stable carbon isotope ratio (δ¹³C values) in the epidermal mucus and muscle tissue of five‐year‐old catfish (Silurus asotus). The isotope ratios in noninvasively sampled mucus changed more rapidly than those in the muscle tissue. As isotopic change in mucus was relatively rapid, this technique can be used over a finer timescale than traditional isotopic analyses using the muscle tissue. The isotopic change half‐life in our experimental condition was 200 days, which would not be short enough for some research purposes. Examining mucus along with the muscle would enable food habits of slow‐growing fishes to be determined over different timescales. However, the rate of isotopic change in the mucus was negatively affected by the size of fish and was slower than the previously reported rates in juvenile steelhead. These findings suggest that mucus turnover rates need to be determined prior to the field data interpretation.