人工气候室群测控系统的设计与应用

使用触摸屏、可编程控制器(PLC)、树莓派微型计算机、组态王、集散控制系统(SCADA)、高清摄像头、影像存证服务以及传感器、执行机构开发了一个人工气候室群智能化测控系统,管理由30个单元组成的人工气候室群。本系统中触摸屏负责采集各单元的环境状态数据,提供人工气候室单元的人机交互界面;PLC完成温室单元的控制逻辑,控制温室加湿、除湿、补光、气调等装置;树莓派微型计算机运行多个定制软件,实现计划库管理、权限分配、协议转换服务、空调控制等功能;组态王运行在管理房微机上,用于人工气候室群的本地管理、配置和数据记录;远程管理依托于基于ClearSCADA构建的设施农业总控中心,实现远程管理、数据采集、存储和配置;各模块间通过网络连接,采用ModbusTCP协议;配套的高清摄像头和影像存证服务提供了内部场景的实时查看和图片记录功能。该系统有效实现了人工气候室群的环境状态采集、环境控制、运行计划管理、远程测控、照片存证等功能,扩展性强,运行稳定。     

UV-B对人工气候室内黄瓜苗期生长、生理及抗氧化系统的影响

紫外线(UV-B)是植物生长发育的关键信号因子.过量或缺少UV-B都会影响作物的抗性、产量和品质.然而,目前植物工厂中适宜黄瓜生长的UV-B强度尚不明确.以黄瓜(Cucumis sativus L.)苗期植株为材料,研究不同强度UV-B对人工气候室内黄瓜苗期植株生长、生理和抗氧化系统的影响.结果表明:与对照相比,UV-B处理黄瓜植株高度降低4.2%~32.0%,叶片中可溶性蛋白含量降低14.2%~28.2%.3.33μmol/(m2·s)UV-B处理植株茎粗增加13.6%~22.3%,叶片中可溶性糖的含量增加22.7%~56.7%,同时激活抗氧化系统,超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性分别提高16.9%~23.2%,23.8%~25.9%,34.1%~50.4%,抗坏血酸含量增加27.4%~36.4%.由此可知,3.33μmol/(m2·s)UV-B有利于人工气候室中黄瓜苗期植株的生长发育、抗氧化酶活性提高及抗氧化物质生成.     

Carbon dioxide exchange of a larch forest after a typhoon disturbance

A typhoon event catastrophically destroyed a 45-year-old Japanese larch plantation in southern Hokkaido, northern Japan in September 2004, and about 90% of trees were blown down. Vegetation was measured to investigate its regeneration process and CO₂ flux, or net ecosystem production (NEP), was measured in 2006–2008 using an automated chamber system to investigate the effects of typhoon disturbance on the ecosystem carbon balance. Annual maximum aboveground biomass (AGB) increased from 2.7 Mg ha⁻¹ in 2006 to 4.0 Mg ha⁻¹ in 2007, whereas no change occurred in annual maximum leaf area index (LAI), which was 3.7 m² m⁻² in 2006 and 3.9 m² m⁻² in 2007. Red raspberry (Rubus idaeus) had become dominant within 2 years after the typhoon disturbance, and came to account for about 60% and 50% of AGB and LAI, respectively. In comparison with CO₂ fluxes measured by the eddy covariance technique in 2001–2003, for 4.5 months during the growing season, the sum of gross primary production (GPP) decreased on average by 739 gC m⁻² (64%) after the disturbance, whereas ecosystem respiration (RE) decreased by 501 gC m⁻² (51%). As a result, NEP decreased from 159 ± 57 gC m⁻² to −80 ± 30 gC m⁻², which shows that the ecosystem shifted from a carbon sink to a source. Seasonal variation in RE was strongly correlated to soil temperature. The interannual variation in the seasonal trend of RE was small. Light-saturated GPP (P_max) decreased from 30–45 μmol m⁻² s⁻¹ to 8–12 μmol m⁻² s⁻¹ during the summer season through the disturbance because of large reduction in LAI.     

小型涡流室柴油机供油与燃烧系统协同匹配

小型涡流室柴油机的供油与燃烧系统优化是满足不断加严排放法规的基础。该文以某170F涡流室柴油机为研究对象,运用模拟计算与试验结合的方法,对其供油及燃烧系统开展研究。借助工程软件构建了供油系统仿真模型,通过设计长型短结构喷油器、优化供油系统参数,来提高喷油压力和优化喷油特性;利用FIRE软件对燃烧过程进行模拟,找出了喷油油线在涡流室内位置及燃烧室容积比的最佳范围。柴油机优化后整机初次试验气体比排放低于国家第三阶段排放限值,CO和HC+NOX分别较原机下降了72.8%和21.3%(八工况循环),标定工况烟度由原机4.5下降到1.2 BSU,有效燃油消耗率较原机下降了约16.1%。该研究工作为小型涡流室柴油机性能提高和节能减排提供了参考。     

Seed priming to mitigate the impact of elevated carbon dioxide associated temperature stress on germination in rice (Oryza sativa L.)

ABSTRACT

Climate change has a negative impact on crop production by inducing several stresses throughout plant growth. As the germination is one of the critical stages, this study was to assess the impact of elevated carbon dioxide (eCO₂) and associated temperature stress on germination of rice. The study was conducted using the rice genotype CO 51 in artificially induced eCO₂ condition using open-top chamber (OTC). The efficiency of seed priming treatment with salicylic acid (SA), citric acid (CA), ascorbic acid (AsA) and distilled water (hydropriming) to alleviate stress due to eCO₂ and temperature were also studied. SA 25 mg l^?1 and AsA 100 mg l^?1 enhanced germination, other seed quality parameters along with α- amylase activity. Also, the activity of antioxidant enzymes like catalase, peroxidase and superoxide dismutase was increased. These parameters positively affected the germination and growth by mitigating the effect of oxidative stress induced under eCO₂ conditions. So, SA, CA and AsA can be effectively used for maintaining seed quality parameters and seedling growth during the stresses.     

Numerical simulation and optimum design on airflow distribution chamber of air-impingement jet dryer

为了改善气体射流冲击干燥机气流分配室流场结构,提高喷管速度分布均匀性,以气体运动微分方程和RNG k-ε湍流模型为基础,利用计算流体动力学软件Fluent对气流分配室内气流流场进行了三维数值模拟,得到了热气流在气流分配室内的流动特征,并对原模型结构进行改进,提出了3类优化方法,同时将最优模型的预测值与试验数据进行了比较。计算结果表明,气流分配室原始结构的速度矢量在气流腔室内部形成2个左右对称的反向涡流区,对应喷管出口速度分布沿高度方向呈先减小后增加的趋势,设计工况下速度偏差比和速度不均匀系数分别达到24.6%和18.1%;减小分配室下端宽度这一常见思路并不能改善气流分配室的速度分布均匀性,而扰流模型则被证明是可行的; 平板扰流模型的效果优于半圆柱扰流模型,其最佳结构参数为平板间距为160 mm且第一块平板较喷管轴线高14 mm,速度偏差比降为7.7%,而速度不均匀系数仅为4.7%,数值模拟结果与试验数据最大偏差不超过8%。该文的研究思路对类似于干燥机气流分配室结构的均匀性设计提供了参考。     

Influence of Storage Environment,Surface Coating,and Individual Shrink Wrapping on Quality Assurance of Guava (<Emphasis Type="Italic">Psidium guajava</Emphasis>) Fruits

Guava (Psidium guajava) fruits of cv. L-49 with individual shrink wrapping using 9 LLDPE film could be successfully stored up to 12 days at ambient and 18 days in evaporative cool chamber with negligible loss in vitamin C content. The untreated fruits lose 25–30% of ascorbic acid within 1week after harvest. Delay in senescence and metabolic activities as supported by less changes in soluble solids, sugars, acidity, respiration, and ethylene evaluation rate was also observed in individual shrink wrapped fruits in cool chamber. The spoilage of fruits by Fusarium rots was significantly less in cool chamber in individually shrink wrapped fruits followed by Sta-fresh treatment. Sta-fresh was more effective in cool chamber than ambient. Individually stored wrapped fruits scored a better value of sensory score than Sta-fresh under both the storage condition.     

Effects of cuvette surface material on ammonia‐, nitrous oxide‐, carbon dioxide‐, and methane‐concentration measurements

Closed‐chamber systems are commonly used to determine gaseous C and N emissions from agricultural soils. We investigated the effects of eight cuvette surfaces on two standard gas concentrations of NH₃, N₂O, CO₂, and CH₄ under laboratory conditions. Cuvette surface materials differentially affected gas adhesion or recovery as a function of the type and the concentration of the gases. Given the strong effects on results of gas measurements in closed‐chamber systems, both the type and the concentration of the measured gases need to be considered in selecting cuvette surface materials.     

Effects of moderate drought on particles retention and physiology of three evergreen shrubs

Moderate drought and vehicular exhaust particles are two common stressors to urban plants. However, it is unclear whether moderate drought affects particle retention by plants and whether stressors, such as moderate drought and exhaust pollution, can interact to affect plant performance. Here, we used an open-top chamber experiment to quantify particle retention per unit leaf area and physiological and biochemical parameters of Pittosporum tobira, Photinia × fraseri, and Euonymus japonicus ‘aurea-marginatus’ over 24 days. Total particle retention of E. japonicus ‘aurea-marginatus’ was significantly higher than the other two species by 1.10 times - 1.45 times. Moderate drought had significant, species-specific effects on particle retention, causing a 45.51% increase in P. tobira and a 51.22% decrease in P. fraseri, but no significant effect on E. japonicus ‘aurea-marginatus’. Superoxide dismutase was activated by drought or exhaust pollution for all plants, reaching its maximum (P. fraseri on the 6th day, the other two species on the 12th day), and then declining. The soluble sugar content of E. japonicus ‘aurea-marginatus’ increased during the first 12 days of stress, while it decreased in the other two species. After 24 days, the relative conductivity of stressed individuals was generally higher and the relative chlorophyll content lower except for P. fraseri. However, a significant decrease in net photosynthetic rate was found only in P. fraseri, and E. japonicus ‘aurea-marginatus’ exhibited the smallest decline in photosynthetic rate. In general, most physiological and biochemical indicators were more sensitive to combination between stressors than to either stressor alone. E. japonicus ‘aurea-marginatus’ may be the most suitable of the three species to be planted in moderate drought and polluted areas for its best particle retention and physiological performance.     

495汽油机进气系统的改进及其进气过程的三维数值模拟

对495汽油机的进气道和燃烧室进行了改进,运用流体分析软件FIRE对改进前后的进气系统进行了较为全面的模拟计算,获得了其内部流场的详细状况,并做了对比分析.实测了改进后不同气门升程下的进气流量,并与模拟计算值进行比较,计算和实验结果基本吻合.结果表明改进后的495汽油机进气系统有更好的流动特性,也验证了三维数值模拟的正确性.