Development and experiment of handheld digitalized and multi-functional forest measurement gun     

徐伟恒  冯仲科  苏志芳  胥辉  焦有权  樊江川 《农业工程学报》2012,28(23):90-99

为了实现森林的数字化、多功能、精准计测,该文研制了一种数字化多功能电子测树枪,该设备以MEMS（micro-electro-mechanical systems）测角传感器、激光测距传感器、电子罗盘等主要硬件为基础,通过测量距离、倾角、磁方位角3个参数,基于三角函数原理,嵌入操作软件,实现了树高测量、林分平均高测量、株数密度测量、角规绕测、任意高度直径测量、基本测量6项功能。并将该设备在河南省、内蒙古等地林场进行了试验,试验结果表明,树高测量精度最高,达99.39%,林分平均高测量精度最低,为94.97%,其他功能精度都在95%以上,可以满足林业外业调查的需要。  相似文献   

旋流泵含气混输数值计算及涡室流场探针测量   总被引：2，自引：2，他引：0  

沙毅  刘祥松 《农业工程学报》2014,30(18):93-100

为探索旋流泵内部流场及气液两相流混输特性,该文通过32WB8-12型旋流泵外特性试验和泵最优工况流场五孔探针测量,得出泵性能曲线和5个测点静压ps、绝对速度v、圆周速度vu、径向速度vr和轴向速度vz分布情况。针对N-S方程中四项力在气液两相流动中的具体表现特性进行力学分析,说明了泵内部两相流动特点及关联因素之间约束关系。阐明了旋流泵含气混输抽吸和扬程形成的基本原理,及空化和气液两相流混输的不同特点。选择性能试验最优工况,基于改进重组化群k-ε湍流模型(RNG k-ε模型),应用Fluent软件对泵内部流场进行数值模拟,得到了3个轴面静压、速度矢量和含气率分布图。证明泵进口轴向运动为主流,气体主要集中在压力较低的进口区域。气相的引入,其微团与液相尺寸、形状及弹性模量的不同,造成两相流场惯性力、摩擦力和浮力发生变化,由此解释了外特性变化及气液抽吸与内部流动之间定性的因果关系。探讨了旋流泵内部气液两相流动速度场和过流通道发生畸变的基本原理,为建立旋流泵内部气液及空化流动模型提供实例。  相似文献   

基于抽样调查地块实测数据的省级水稻单产遥感估算     

彭代亮  周炼清  黄敬峰  周斌  王福民 《农业工程学报》2011,27(9):106-114

利用统计局抽样调查地块实割实测标准单位面积产量数据及空间位置信息,在研究水稻种植区MOD09GA、MYD09GA EVI （enhanced vegetation index）数据结合使用可行性分析的基础上,进行湖南省省级水稻单产遥感估算。结果表明：在水稻种植区,水稻生长期间有超过50%、85%、95%的MOD09GA与MYD09GA EVI偏差绝对值分别小于0.03、0.08、0.1。水稻遥感估产模型以二次非线性模型或回归模型精度较高,且时相集中在水稻生长的孕穗期到抽穗期。在省级水平上,与实测值相比,基于统计局统计抽样调查地块实割实测标准单位面积产量数据的水稻单产遥感拟合结果相对误差小于2%,预测结果的相对误差接近5%,且实测值与模拟值集中分布在1∶1线附近,说明预测结果与统计值在空间分布上具有较好的一致性。  相似文献   

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

Martina Predotova  Roland Kretschmann  Jens Gebauer  Andreas Buerkert 《植物养料与土壤学杂志》2011,174(3):347-349

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.  相似文献   

Long term and seasonal courses of leaf area index in a semi-arid forest plantation   总被引：3，自引：0，他引：3  

Michael Sprintsin  S. CohenK. Maseyk  E. RotenbergJ. Grünzweig  A. KarnieliP. Berliner  D. Yakir 《Agricultural and Forest Meteorology》2011,151(5):565-574

Effective leaf area index (LAI_e) in the semi-arid Pinus halepensis plantation, located between arid and semi-arid climatic zones at the edge of the Negev and Judean deserts, was measured bi-annually during four years (2001-2004) and more intensively (monthly) during the following two years (2004-2006) by a number of non-contact optical devices. The measurements showed a gradual increase in LAI_e from ∼1 (±0.25) to ∼1.8 (±0.11) during these years. All instruments, when used properly, gave similar results that were also comparable with actual leaf area index measured by litter collection and destructive sampling and allometric estimates. Because of the constraint of clear sky conditions, which limited the use of the fisheye type sensors to times of twilight, the fisheye techniques were less useful. The tracing radiation and architecture of canopies system, which includes specific treatment of two levels of clumpiness of the sparse forest stand, was used successfully for the intensive monitoring. The mean clumpiness index, 0.61, is considered representative for the specific environment. Finally, the LAI_e measurements at the start of each season were used to constrain phenology-based estimates of annual LAI_e development, resulting in a continuous course of LAI_e in the forest over the five-year period. Intra-seasonal LAI_e variation in the order of 10% of total LAI_e predicted by the model was also observed in the intensive TRAC measurements, giving confidence in the TRAC system and indicating its sensitivity and applicability in woodlands even with low LAI_e values. The results can be important for forest management decision support as well as for use in evaluation of remote sensing techniques for forests at the lowest range of LAI_e values.  相似文献   

Root development in potato and carrot crops – influences of soil compaction     

Tor J. Johansen  Mette G. Thomsen  Anne-Kristin Løes  Hugh Riley 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(2):182-192

Row crops such as potatoes (Solanum tuberosum L.) and carrots (Daucus carota L.) are of high economic value in the Nordic countries. Their production is becoming more and more specialized, including continuous arable cropping and heavier farm machinery, with increased risk of soil compaction. The result may be restricted root development and economic losses. Potatoes have widely branched adventitious roots, whereas carrots have taproots with fibrous roots extending from them. Under optimal soil conditions, total root length per surface area may reach more than 10 km m^?2 for both species. Maximal root depth is about 140 cm for potato and more than 200 cm in carrots. Most of the root mass is usually distributed within the upper 100 cm, whereof more than 50% may be deeper than 30 cm. Soil compaction causes a dense soil with few large pores, poor drainage and reduced aeration, especially in wet soils with low organic matter content and high proportions of silt or clay. With compacted subsoil layers, roots will be concentrated more in the upper layers and thus explore a smaller soil volume. This will lead to reduced water and nutrient uptake, reduced yields and low nutrient utilization efficiency. In this review article, we describe the interactions between root development and soil conditions for potatoes and carrots, with special focus on sub-optimal conditions caused by soil compaction. We also discuss the effects of tilling strategies, organic material, irrigation and fertilization strategies and controlled traffic systems on root and yield development. To reduce subsoil compaction there is a need to implement practises such as controlled traffic farming, new techniques for ploughing, better timing of soil operations, crop rotations with more perennial crops and supplements of organic material. Moreover, there is a need for a stronger focus on the impacts of farm machinery dimensions.  相似文献   

Flow resistance in mobile bed rills shaped in soils with different texture     

Francesco G. Carollo  Costanza Di Stefano  Alessio Nicosia  Vincenzo Palmeri  Vincenzo Pampalone  Vito Ferro 《European Journal of Soil Science》2021,72(5):2062-2075

  相似文献   

手持式数字化多功能电子测树枪的研制与试验   总被引：9，自引：6，他引：3  

徐伟恒  冯仲科  苏志芳  胥辉  焦有权  樊江川 《农业工程学报》2013,29(3):90-99

为了实现森林的数字化、多功能、精准计测,该文研制了一种数字化多功能电子测树枪,该设备以MEMS(micro-electro-mechanical systems)测角传感器、激光测距传感器、电子罗盘等主要硬件为基础,通过测量距离、倾角、磁方位角3个参数,基于三角函数原理,嵌入操作软件,实现了树高测量、林分平均高测量、株数密度测量、角规绕测、任意高度直径测量、基本测量6项功能。并将该设备在河南省、内蒙古等地林场进行了试验,试验结果表明,树高测量精度最高,达99.39%,林分平均高测量精度最低,为94.97%,其他功能精度都在95%以上,可以满足林业外业调查的需要。  相似文献   

兼用短角牛改良秦川牛效果研究--眉县短秦一、二代母牛生长发育及体型变化分析(之二)     

毛玉胜  贾永宏  王纪劳 《中国牛业科学》2000,26(4):9-12,26

对短秦F1、F2和本地母牛初生、6、12、18、24月龄体尺、体重进行测定,并对其生长发育强度进行对比分析.结果表明,在农村粗放饲养条件下,F2牛初生6、12月龄体重比本地牛分别增加4.3、37.2、35.6kg,相应提高16.6%、28.2%、17.9%;F1牛18、24月龄比本地牛分别增加30.9、47.8kg,提高11.0%和15.6%,改良牛纠正了本地牛的尖斜尻缺点,且生长发育快,增重效果明显,体躯有向肉乳兼用型发展趋势,若加强断奶后的培育,效果更好.  相似文献   

Estimation of Leaf Area in Greengram by Non-destructive Linear Measurements     

K. Manian    K. Balakrishnan    Prof. Dr.  Natarajaratnam K. Mohanasundaram 《Journal of Agronomy and Crop Science》1987,158(2):96-98

The leaf area by non-destructive linear measurements have been made in eight cultivars of greengram. The regression equation was Y = 1.58 + 1.79 (X), r = 0.9988** while X = L × W. L and W are the maximum length and width of the terminal leaflet of a trifoliate leaf respectively. Y = leaf area of a trifoliate leaf. This study indicated that this equation can be used for a measuring of the leaf area in situ irrespective of the position of the leaves and variety in greengram.

Zusammenfassung

Abschätzung der Blattfläche von Mung-Bohne mit Hilfe einer nichtdestruktiven linearen Messung
Die Untersuchungen zu einer nichtdestruktiven linearen Messung wurden bei acht Sorten der Mung-Bohne durchgeführt. Die Regressionsgleichung war Y = 1,58 + 1,79 (X), r = 0,9988**, während ×= L × W war. L und W sind die Maximumlängen und Breiten des terminalen Blattes eines dreifach gefiederten Blattes. Y = Blattfläche eines dreifach gefiederten Blattes. Die Untersuchung zeigt, daß die Gleichung für die Messung der Blattfläche in situ bei Mungo-Bohnen verwendet werden kann, unabhängig von der Position des Blattes und der Sorte.  相似文献