不同土层氮肥配施方式对夏玉米生长发育及氮肥利用的影响

为明确不同土层氮肥配施方式对夏玉米生长发育及氮素利用的影响,利用改进的玉米深松分层可调施肥精播机,通过设置不同肥料类型、不同土层施肥深度和比例,研究深松分层施肥技术对铁茬播种模式下夏玉米植株叶面积指数、干物质积累、产量和氮肥利用效率的影响。结果表明:在相同施氮量的条件下,使用免耕深松分层施肥技术的玉米叶面积指数、干物质积累量、产量及氮肥利用效率均显著高于传统"一炮轰"施肥技术;产量和氮肥偏生产力均增加了5.5%~7.9%。不同免耕深松分层施肥方式中,大喇叭口期追施尿素的施肥方式均较一次性施用控释肥方式获得了较高的产量、干物质积累量和氮肥偏生产力,但差异未达显著水平;其中,以免耕深松分别在8 cm和12 cm深度,按照3:7比例施入复合肥作为基肥,配合大喇叭口期追施尿素的施肥方式获得最高产量和氮肥偏生产力,产量均较传统施肥方式增加了7.9%。因此,免耕深松分层施肥技术在夏玉米免耕铁茬播种区可以达到节本增效的目的,对提高玉米产量和氮肥利用具有重要意义。     

普通肥、控释掺混肥分层施肥对小麦生长的影响

为了研究不同层次施肥对土壤养分及作物生长的影响,通过小麦盆栽试验,以农民习惯施肥(普通肥撒施后翻耕)为对照,设置不施肥、控释掺混肥混施、普通肥1层施肥加追肥、普通肥和控释掺混肥各1层(深度5cm)、2层(5,10cm)、3层(5,10,15cm)施肥处理,筛选出普通肥、控释掺混肥各自最优的施肥层次,为田间分层施肥特别是目前农业推广的种肥同播技术提供支持。结果表明:与对照相比,普通肥1层、2层施肥处理显著增产14.02%和15.83%;普通肥两层施肥处理小麦生物量显著增加13.44%;控释掺混肥2层、3层施肥相比控释掺混肥混施处理显著增产7.47%和5.55%,小麦生物量差异不显著。小麦各个生长期的氮素供应普通肥以1层施肥或2层施肥为好,而控释掺混肥以2层施肥或3层施肥为好;不同处理的土壤有效磷、速效钾含量差异不显著。普通肥分层施肥处理氮肥利用率比对照分别提高44.4%,40.7%和62.9%,磷肥利用率分别提高35.7%,64.3%和42.8%,钾肥利用率分别提高16.7%,33.3%和53.3%,差异均达显著水平;而控释掺混肥各处理氮、钾肥利用率差异不显著,磷肥利用率则分别显著提高35.0%,30.0%和35.0%。在农业生产中,建议普通肥以2层(深度5,10cm)施肥,控释掺混肥以2层(5,10cm)或3层(5,10,15cm)施肥的方式进行施肥。     

AWE方法分析近地偶极天线

针对傅里叶变换域内 Green 函数的特点,通过变量替换的方法,并借助外推算法,完成对阻抗矩阵及其阻抗矩阵的导数的计算,实现了媒质分层条件下的渐近波形估计(AWE)算法。数值试验结果表明,在考虑的整个频率范围内,适当选择几个频点,采用 AWE 方法可以快速地获得天线的宽带特性。     

An Elastic Theory Approach and Parametric Analysis of Pile Group in Layered Soils

Based on the technique proposed by Muki & Sternberg, a rigorous analytical method for calculating the interaction factor between two piles with different lengths, diameters and properties is presented. The pile group in layered soils is calculated by using the principle of superposition. The validity of the presented method has been verified through comparing with those from other existing solutions. A parametric analysis is made to study the pile group settlement and the loads shared by the individual pile. The proposed interaction factors of pile-pile can consider the strengthening effect of intervening piles. The proposed method can be used to analyze the large pile group.     

粘弹性层状半空间的动力响应及其在动力基础中的应用

An integral representation of the surface displacements of layered viscoelastic half-space subjected to normal harmonic exitation on the surface is deduced using transmission matrices. Based on it,a method is proposed to calculate the displacement and the     

上层土壤密度对模拟指流层状土壤水分入渗的影响

通过室内模拟指流,利用回归分析法进行分析,建立了以上层土壤密度为参数的Kostiakov和Philip模型对模拟指流的层状土壤入渗的改进模型,并进行了验证。结果表明,入渗时I;7相同时,累积入渗量随着上层土壤密度的增加而减小;Kostiakov和Philip模型都适合于模拟有指流产生的层状土壤的入渗,其相关系数都在0．...     

基于分层信息融合的木材干燥过程含水率在线检测

木材干燥过程是一个复杂的强耦合、非线性的动力系统,木材干燥的关键是木材含水率参数的检测。研究中依据多传感器信息融合技术,构建符合木材干燥过程的木材含水率在线检测分层融合体系。数据层融合实现干燥窑内各种参数传感器的小波滤波与在线估计,特征层融合实现环境参数（温度、湿度）与木材含水率之间LSSVM模型的建立,在此模型基础上实现木材含水率的预测输出。仿真试验研究表明,基于分层信息融合技术可有效实现木材含水率在线检测预测,通过在线检测融合平台可以实现根据不同树种,不同干燥工艺直观地将预测结果显示出来,为木材干燥自动控制系统的控制决策提供依据,具有良好的工业实际应用价值和前景。     

小型油菜籽分层床式干燥设备的数值模拟及其优化

基于计算流体力学(computational fluid dynamics,CFD)技术及多孔介质模型对干燥室内气流场进行数值模拟,并根据模拟结果对小型油菜籽分层床式干燥设备进行优化。结果表明:优化后的干燥设备能够满足油菜籽干燥要求,通过数值模拟可得单一纵向通风时干燥室内存在热风死区,使得干燥均匀性较低,增加横向通风后干燥室内流场分布较为均匀,油菜籽与热风接触面积增大,提高干燥效率及均匀性,且利用生物质能源能够实现节能减排的要求。     

Performance and Analysis of a Model for Describing Layered Leaf Area Index of Rice

Layered leaf area index (LAIk) is one of the major determinants for rice canopy. The objective of this study is to attain rice LAIk using morphological traits especially leaf traits that affected plant type. A theoretical model based on rice geometrical structure was established to describe LAIk of rice with leaf length (Li), width (Wi), angle (Ai), and space (Si), and plant pole height (H) at booting and heading stages. In correlation with traditional manual measurement, the model was performed by high R2-values (0.95-0.89, n=24) for four rice hybrids (Liangyoupeijiu, Liangyou E32, Liangyou Y06, and Shanyou 63) with various plant types and four densities (3 750, 2 812, 1 875, and 1 125 plants per 100 m2) of a particular hybrid (Liangyoupeijiu).The analysis of leaf length, width, angle, and space on LAIk for two hybrids (Liangyoupeijiu and Shanyou 63) showed that leaves length and space exhibited greater effects on the change of rice LAIk. The radiation intensity showed a significantly negative exponential relation to the accumulation of LAIk, which agreed to the coefficient of light extinction (K). Our results suggest that plant type regulates radiation distribution through changing LAIk. The present model would be helpful to acquire leaf distribution and judge canopy structure of rice field by computer system after a simple and less-invasive measurement of leaf length, width, angle (by photo), and space at field with non-dilapidation of plants.