区域自动站信息统计、查询系统

自动站资料的应用是自动站发挥作用的关键。气象资料实时查询系统对气象资料共享、服务产品的开发与决策服务将起到重要的作用。     

全自动称重式雨量计的研制及性能分析

为了精准刻画降雨过程特征,研制了一种具有野外复杂条件下普遍适用的全自动称重式雨量计,该仪器以STM32单片机为核心,利用A/D转换芯片对称重传感器的电压信号进行放大处理,获取分辨率为0.01 mm的分钟级别的降雨数据。试验结果表明,该雨量计测量标准差为0.02 mm/min,测量准确度最高为98.67%,说明该仪器监测精度高且适用范围广。称重式雨量计分辨率高,对微小雨滴反应灵敏,使得其监测结果较翻斗式雨量计大。此外,利用称重式雨量计在王东沟小流域进行野外自然降雨观测,发现该小流域自然降雨集中在5-9月,主要以次降雨量≤5 mm的降雨为主,而次降雨量为＞10~25 mm的降雨对降雨总量贡献最大。该仪器可以实时准确地监测降雨全过程,可为提高降雨监测技术的精准化和自动化水平提供参考。     

不同网孔与筒体模型对Y型网式过滤器性能的影响

Y型网式过滤器广泛运用于微灌系统,其良好的水力性能是保证微灌系统稳定运行的关键,为了分析其水力性能,该研究采用数值模拟和物理试验相结合的方法,分析了网式过滤器在3种滤网网孔（正方形、圆形、菱形）以及3种筒体弧线角度（0°、15°、30°）下,过滤器内压降系数、滤芯网面流量分布、内部流场、压力分布等水力特性的变化。结果表明：物理试验与数值模拟之间的水头损失系数平均差异为9%,表明了数值模拟的可靠性,其中圆形网孔过滤器水头损失系数最大,正方形次之,菱形最小;滤网网孔形状对过滤器网面过流量分布的影响较大,正方形网孔过滤器的中速过流量区域占比最高达到了47.5%,圆形次之,菱形最小仅为26.5%。过滤器的水头损失随着筒体弧线角度的增加而逐渐减小,35°的压降系数较0°的减小了73.15%,网面流量的分布也随着角度的增加变得更为均匀,其中35°的中速过流量区域面积较0°增大了71.48%,水力性能明显提高;此外随着筒体弧线角度的增加,出口侧中上段滤网处的内外压差明显减小。因此在实际微灌系统中,选择网孔为正方形、筒体弧线角度30°的过滤器,其内部流场缓和、网面流量分布均匀,提高了过滤器的水力性能和使用寿命。该研究成果可为网式过滤器结构优化提供设计方案与理论依据。     

Development of an agricultural weather policy

Climate is one of the most important factors determining the sustainability of agricultural production systems. More emphasis must be placed on understanding the influence of changing climate conditions on sustainable agricultural systems, given the increasing limitations of the natural resource base. Agrometeorologists can play a leading role in bridging the gaps between the diverse multi-disciplinary fields of science, by reaching out to farmers, extension service personnel, and the agricultural business community. The farming community must cope with issues of climate variability and climate change, and, the challenge for agricultural meteorologists is to develop a coordinated national agricultural weather policy to assist agriculture as it deals with these issues. Agricultural weather policy must be formulated so that proactive long-term preparedness activities are strengthened to ensure agricultural sustainability and to preserve natural resources. Preparedness must be the essential foundation of an agricultural weather policy that builds upon mitigation measures and adaptation strategies to cope with climate variability and climate change as it affects agriculture, forestry, rangelands, and fisheries.     

Calculation of the shortwave radiation flux from weather station data in evapotranspiration studies

A statistical relationship between the measured daily flux of short-wave radiation, the extra-terrestrial radiation and the duration of bright sunshine was established. Used were continuous daily data from the Weather Service station of Göttingen, West Germany (51°33′N, 9°57′E) for the period 1969–1980. The analysis was similar to the procedure proposed by Kimball (1927). Daily values for the extra-terrestrial short-wave radiation and for the maximum possible duration of sunshine were calculated from expressions developed by Swift (1976). It was found that in Göttingen, for an assumed solar constant radiative flux of 1352 W.m^?2, the constants A and B in the Kimball equation were 0.18 and 0.47. It was also found that these average values varied from year to year and also for different seasons of the year. It is pointed out that if radiation values calculated with the Kimball equation are used to estimate the daily evapotranspiration, care must be taken that proper regional constants are used.     

粉碎机筛网破损在线自动识别装置设计与试验

在饲料生产过程中,目前主要依靠人工获取粉碎原料样本,通过感官或标准筛识别样本的粒度,从而判定粉碎机筛网是否破损。为了实现粉碎机筛网破损在线自动识别,该研究设计了一种自动取样机构,应用机器视觉技术,搭建了粉碎机筛网破损在线自动识别系统。该系统主要由取样机构、筛分机构及图像采集机构等组成,采用西门子S7-200PLC可编程控制器实现装置的自动控制,其中取样机构用于在线自动获取饲料样本,筛分机构实现样本中细粉的剔除,图像采集机构采集剔除细粉后的颗粒图像,建立样本图像数据集。使用Python进行图像处理,以样本图像中大颗粒的平均等效投影圆直径和平均最小外接矩形面积作为特征参数,分别运用阈值法、K近邻法和径向基函数支持向量机建立筛网破损识别模型。结果表明,当将2个特征参数同时输入K近邻法模型且临近值个数k为3时,模型对孔径1.0和2.0 mm的筛网是否破损的测试集识别正确率最高分别为94%和96%。该研究设计的粉碎机筛网破损在线自动识别装置可以实现粉碎机筛网破损在线自动识别,为粉碎机筛网破损在线自动识别提供了新的方法和技术支撑。     

The performance of a greenhouse heated by an earth-air heat exchanger

An earth—air heat exchanger consisting of 20 aluminium pipes 15 m long, 0.2 m in diameter and 0.2 mm thick, was installed at a depth of 2 m in a greenhouse of floor area 150 m².The greenhouse air temperature was adjusted by blowing the greenhouse air through the pipe system whenever the air temperature dropped below 12°C or exceeded 28°C. Recorded from November to May, this resulted in a minimum mean night air temperature of 8.1°C inside the greenhouse with an absolute minimum of 7°C while the outside minimum mean and absolute minimum air temperatures were −0.8°C and −3.0°C, respectively, during the same period.The electrical energy used by the fan of the earth—air exchanger was only 20% of the energy input to the greenhouse from the earth—air heat exchanger.     

旱地蔬菜钵苗自动移栽机栽植性能试验

为了提高蔬菜苗机械化移栽作业效率,实现旱地蔬菜钵体苗移栽自动化,研制了旱地蔬菜钵苗自动移栽机,主要由椭圆-不完全非圆齿轮行星系旋转式取苗机构、横向纵向间歇送苗机构、偏心圆盘吊杯式栽植器、动力传递系统等组成。为了获得该机的作业性能,以苗龄35 d的钵体番茄苗为移栽对象,分别在栽植频率45、60、75、84株/min时进行低速移栽试验,以96株/min的栽植频率进行高速移栽试验,按照机械行业标准JB/T 10291-2013《旱地栽植机械》测定了株距变异系数、漏栽率、栽植深度合格率、栽植合格率,参照农业行业标准NY/T 1924-2010《油菜移栽机质量评价技术规范》测定了直立度合格率。田间试验结果表明,在栽植频率为45~96株/min范围内,株距变异系数、漏栽率随栽植频率增加而略有增大,其平均值分别为6.6%~8.9%、1.7%~2.8%,栽植深度合格率、直立度合格率、栽植合格率随栽植频率增加略有下降,其平均值分别为97.5%~98.9%、96.7%~97.8%、91.1%~94.7%,株距变异系数、漏栽率、栽植深度合格率、栽植合格率均达到机械行业标准要求,直立度合格率也达到农业行业标准中的规定值。旱地蔬菜钵苗自动移栽机送苗机构、取苗机构、栽植器、整机行走配合协调,能够自动完成送苗、取苗、植苗、覆土等钵苗体移栽工序,作业性能良好。     

A check on the efficiency of an air-bubble screen using acoustic measurements and an artificial tracer

Purpose

A working group, composed of the University of Genoa (Italy), responsible for monitoring the dredging of the Port of Genoa, and Royal Boskalis Westminster N.V. (The Netherlands), responsible for the dredging activities, carried out an experiment on closing a landfill area with a double air bubble-screen (ABS) to verify the efficiency both of this method of containing sediment and of the measurement method applied.

Materials and methods

Within the Port of Genoa dredging, which was started in 2009, the dredged material is used to fill two areas between existing quays. To contain the sediment to be placed into a third subbasin without interrupting the passage of the barges which discharge the sediment, the use of an ABS was proposed as a barrier to the spreading of the sediment. The experiment was carried out during a 4-day oceanographic campaign to verify, preliminarily, the results under different weather and sea conditions. An artificial tracer, rhodamine water tracing (RWT), was used in varying concentrations to simulate the spreading of the sediment, and an RWT sensor and an acoustic Doppler current profiler (ADCP) were used to measure the RWT distribution and verify the efficiency of the ABS.

Results and discussion

The high turbidity in the port and the high rate of RWT dilution made it relatively difficult to detect the RWT. The RWT sensor sometimes measured higher values than expected probably due to the following: the recirculation of the tracer in current eddies, other sensible suspended matter and adsorption of RWT on suspended matter. The internal ABS could not retain all the RWT, possibly because it was much weaker than the external one, and because mitigating measures, like silt screens or ABSs, are not totally closed and should not be used if complete impermeability is required. The ABS introduction accentuated the natural separation between the basin and the channel water bodies creating a barrier between the two basins.

Conclusions

An ABS installed at the entrance to a confined area with low dynamics results in a circular vertical flow with the potential to retain suspended sediments within an enclosed area. The meteorological variability during the tests showed that a weak ABS could malfunction in the presence of strong wind condition. The results showed that the ADCP is a suitable instrument to highlight the ABS position and its effect on the surrounding hydrodynamics. Further research, using a sediment tracer, is required to study with greater detail the effects of the ABS on the water column.     

间歇式自动取样条播排种器排种性能检测试验台研制

针对条播作物排种器进行室内台架性能检测时,人工检测播种均匀性费时费力、自动化检测手段缺乏等问题,该文设计了一种条播排种器排种性能检测试验台,利用间歇式自动取样机构,实现定时定距自动化取样及排种均匀性检测。其工作原理是种子落入传送带上形成种子带,随传送带一起前进,当运动至取样板处时,气泵驱动取样板以均匀的速度往复运动,将特定距离的种子带推离出种带,并分散成弧形,采用数码照相机获取样本种子图像,利用Matlab图像处理技术,获取样本种子数量,判断所测试排种器的排种性能。采用单片机控制排种轴转速、取样板的启停及运动方向,并通过上位机显示。对试验台关键结构和参数进行设计,确定种带宽度为30 mm,护种板长度150 mm,与传送带之间距离控制在2～3 mm。为减少种子堆叠和黏连,保证样本种子带均匀排列,易于后期图像处理,设计了"一"、"T"和"工"字型3种结构的取样板,通过种子受力与运动规律分析,确定"T"型取样板为最优结构,取样长度L为40 mm。以外槽轮排种器播种小麦为研究对象,使用Design-Expert软件进行中心旋转组合设计试验,结果表明,传送带驱动电机转速分别为20、28.79和28.79 r/min时,样本种子堆叠率分别为100%、92.34%和75.21%;排种量6 g/s时,样本种子堆叠率最高,为40.15%。与人工定距取样检测方法的对比试验结果表明,间歇取样检测法利用图像批量处理获取样本种子数量的时间约为5 s;而人工定距测试的平均耗时为1 min,而且样本数量越多,耗时越长。试验结果表明,间歇式自动取样的条播排种器排种性能检测试验台设计合理,能够大大提高排种器排种性能检测效率,可为条播作物的排种器排种性能检测试验台的优化设计提供参考。     

梳脱台高度自动控制系统建模与计算机仿真

介绍了基于PID控制算法的梳脱式联合收割机梳脱台高度调节自动控制系统。分析了4LS-150型梳脱式联合收割机液压提升机构及电液比例控制系统原理；建立了梳脱台高度调节液压控制系统的数学模型，并对建立的传递函数在MATLAB中进行了仿真和PID校正。仿真结果表明，将该系统用于梳脱台高度调节自动控制，可以取得令人满意的控制效果。     

The effect of chinook weather on urban heat islands and air pollution

Urban heat island intensity is stronger and air quality poorer under a chinook than under nonchinook weather. These discrepancies are explained in part by the observed differences in wind pattern, atmospheric stability, and mixing depth associated with these weather conditions. Heat island intensity appears to be reinforced by poor air quality in chinook weather.     

Effects of panicles on infrared thermometer measurements of canopy temperature in wheat

A study was conducted in Phoenix, AZ on stressed and unstressed field plots of Anza wheat (Triticum aestivum L.) on an Avondale loam soil (a fine, loamy, mixed calcareous hyperthermic Anthropic Torrifluvent) to determine effects of panicles on the apparent canopy temperature and their consequent impact on the estimation of crop stress. The panicles were removed from a 1.5 × 4-m sample of each plot by extracting the peduncle from the upper sheath. For each treatment canopy radiative temperature measurements were made from vertical and oblique angles (30° from the horizontal), using an 8° field-of-view (FOV) infrared thermometer, at half-hour intervals from sunrise to sunset on 20, 22, and 30 April. Complementary measurements included leaf water potential and leaf diffusive resistance.Apparent canopy temperatures obtained from the oblique view of the canopy with panicles and under well-watered conditions were 2°C warmer than those of the unstressed canopy without panicles. In the stressed plot the canopy with panicles was 1°C cooler than that without panicles, but this effect was only noticed around 1200 MST. The temperature difference between viewing angles was apparently caused by different percentages of panicle area viewed by the radiometer. In the vertical view panicles contributed to 3% of the total viewed area while at the 30° oblique view panicles comprised 40% of the area. Since energy balance calculations of a non-transpiring cylinder with dimensions similar to a typical wheat panicle showed its temperature would remain very close to that of the surrounding air, canopy temperatures were adjusted for the proportion of panicles viewed assuming they were in equilibrium with air temperature. Results showed the corrected canopy temperatures of the canopy with panicles were the same as those measured in the canopy without panicles. Such a correction is necessary to avoid an overestimate of the stress level and an underestimate of differences between treatments. Crops with non-transpiring and/or well-ventilated morphological structures above the foliage will require this correction if radiative canopy temperatures are to be used in irrigation management programs or stress detection studies.     

Effects of agrochemicals on weather and climate

In the context of a broad definition of agrochemistry, any chemicals produced by agricultural activities may be included here. Interactions between agrochemicals and their environment are the central theme of this paper. This is elucidated in terms of the alterations of radiant energy transfer, heat budget, and water balance at the interface of air and ground. The disrupted states of the atmosphere are presented by climatic elements, weather phenomena, and edaphic conditions. Realizing that the whole earth-atmosphere system tends to approach a state of minimal free energy, a step by step combination of the physical and/or chemical process is given. Emphasis is on the visible and infrared radiant energy transfer, attenuation, nucleation, sorption-condensation, fermentation, combustion, and radiative heating processes. Although this paper stresses the micro-mesoscale weather phenomena and short term effects, agrochemical impact on long-term and global weather and climate should not be ignored. Due to lack of study in this subject area, recommendations for future research stress both experimental and mathematical modeling techniques.     

考虑光伏组件发电性能的自动除尘系统运行时间优化

该文针对自动除尘系统运行过程中动态遮挡对光伏组件输出特性影响规律和系统运行后除尘效果进行了研究分析,进而指导光伏组件自动除尘系统运行开启时刻与持续时间的设置,以实现最优化的除尘效果。结果表明：系统在横向（清扫毛刷运行过程平行于水平面）和纵向（清扫毛刷运行过程倾角等于光伏组件安装倾角）各运行周期中,清扫毛刷每经过一排电池组均会使光伏组件输出参数按V型规律变化,自动除尘系统上行时清扫装置对光伏组件的动态遮挡面积相对下行过程增加1.6150%后光伏组件输出功率低谷值下降40%左右;自动除尘系统运行效果随积灰量呈正相关变化;各类光伏组件的除尘过程应避开光伏组件有功率输出的时间段进行,根据地区与季节的不同定在日出之前10 min开始运行,可实现最优的除尘效果。     

水稻秧盘自动码垛机的设计与试验

针对水稻工厂化育秧播种完成的秧盘人工取盘和层叠堆放劳动强度大、效率低、后续运输不便等问题,该研究设计了一种水稻秧盘自动码垛机,可完成秧盘精确夹取、转移和码垛;阐述了码垛机的基本结构和工作原理,对关键部件进行设计,以可编程逻辑控制器(Programmable Logic Controller,PLC)作为控制核心,搭建了...     

Experiments on the effects of seedbed characteristics on seedling emergence in a dry weather situation

A research program concerning the seedbed preparation problems in Swedish agriculture included a series of pot experiments in shallow plastic boxes. Seedbeds of well-defined characteristics were arranged, and seedling emergence was determined by daily plant countings. In the experiments reported, the main subject of study was the efficiency of the seedbed in controlling evaporation. Clay or clay loam soils were used, and the crops were mainly small grain cereals.Seven experiments with unstratified seedbeds showed that for small grains in a dry weather situation, the seed should be placed directly onto the moist bottom of a harrowed layer, which should be 4–5 cm deep and mainly consist of aggregates smaller than 4 mm. If the bottom layer contains less than 5% plant available water, or if a fine enough seedbed structure cannot be produced, the depth of both harrowing and sowing should be increased. In four experiments with stratified seedbeds, no reasons were found for sorting the coarse aggregates to the soil surface, provided the initial moisture content increased with depth.Effects of seed quality were studied in two experiments. Seed lots with equal germinability under optimum moisture conditions gave large differences in emergence in a moisture stress situation. Within a rather wide seed size range, the size as such had only minor influence on the emergence rate.     

基于级联视觉检测的樱桃番茄自动采收系统设计与试验

樱桃番茄串生长姿态多样、果实成熟度不一,采摘机器人进行“粒收”作业时,常面临果梗干涉末端执行器、成熟度判断错误等问题,导致采摘效率低下、难以有效实现分级采收。针对上述问题,该研究提出一种级联视觉检测流程,包括采收目标检测、目标果实特性判别、果实与果梗位置关系判断3个关键环节。首先根据农艺要求按成熟度将番茄果实分为4个等级,引入YOLOv5目标检测模型对番茄串和番茄果实进行检测并输出成熟度等级,实现分期采收。然后对果实与果梗的相对位置进行判断,利用MobileNetv3网络模型对膨胀包围盒进行果实与果梗相对位置关系判断,实现末端执行器采摘位姿控制。日光温室实际测试结果表明,本文提出的级联检测系统平均推理用时22 ms,在IOU（intersection over union）阈值为0.5的情况下,樱桃番茄串与果实的平均检测精度达到89.9%,满足采摘机器人的视觉检测精度和实时性要求,相比末端执行器以固定角度靠近待采目标的方法,本文方法采收效率提升28.7个百分点。研究结果可为各类果蔬采摘机器人研究提供参考。     

The effect of temporal aggregation of weather input data on crop growth models’ results

Weather data are essential inputs for crop growth models, which are primarily developed for field level applications using site-specific daily weather data. Daily weather data are often not available, especially when models are applied to large regions and/or for future projections. It is possible to generate daily weather data from aggregated weather data, such as average monthly weather data, e.g. through a linear interpolation method. But, due to the nonlinearity of many weather-crop relationships, results of simulations using linearly interpolated data will deviate from those with actual (daily) data. The objective of this study was to analyse the sensitivity of different modelling approaches to the temporal resolution of weather input data. We used spring wheat as an example and considered three combinations of summarized and detailed approaches to model leaf area index development and associated radiation interception and biomass productivity, reflecting the typical range of detail in the structure of most models. Models were run with actual weather data and with aggregated weather data from which day-to-day variation had been removed by linear interpolation between monthly averages.Results from different climatic regions in Europe show that simulated biomass differs between model simulations using actual or aggregated temperature and/or radiation data. In addition, we find a relationship between the sensitivity of an approach to interpolation of input data and the degree of detail in that modelling approach: increasing detail results in higher sensitivity. Moreover, the magnitude of the day-to-day variability in weather conditions affects the results: increasing variability results in stronger differences between model results. Our results have implications for the choice of a specific approach to model a certain process depending on the available temporal resolution of input data.