Integrating multiple electromagnetic data to map spatiotemporal variability of soil salinity in Kairouan region,Central Tunisia

Soil salinization is a major problem affecting soils and threatening agricultural sustainability in arid and semi-arid regions,which makes it necessary to establish an efficient strategy to manage soil salinity and confront economic challenges that arise from it.Saline soil recovery involving drainage of shallow saline groundwater and the removal of soil salts by natural rainfall or by irrigation are good strategies for the reclamation of salty soil.To develop suitable management strategies for salty soil reclamation,it is essential to improve soil salinity assessment pro cess/mechanism and to adopt new approaches and techniques.T his study mapped a recovered area of 7200 m2 to assess and verify variations in soil salinity in space and time in K airouan region in Central Tunisia,taking into account the thickness of soil materials.Two electromagnetic conductivity meters(EM38 and EM31)were used to measure the electrical conductivity of saturated soil-paste extract(ECe)and apparent electrical conductivity(E Ca).Multiple linear regression was established between ECe and ECa,and it was revealed that ECa-EM38 is optimal for E Ce prediction in the surface soils.Salinity maps demonstrated that the spatial structure of soil salinity in the region of interest was relatively unchanged but varied temporally.Variation in salinity at the soil surface was greater than that at a depth.These findings can not only be used to track soil salinity variations and their significance in the field but also help to identify the spatial and temporal features of soil salinity,thus improving the efficiency of soil management.     

基于移动4G的株距自适应玉米收割机优化设计

为了提高玉米收割机的株距的自适应能力、降低漏采率、提升工作效率,设计了一种新的株距自适应玉米收割机,大大提高了玉米收割机的作业精度和效率。依据移动4G信号的传播特性,设计了玉米株距实时测量系统,针对中国4G现场测试环境,研究提出了一种电波传播特性测量与建模方法,结合高性能测试仪器和虚拟仪器技术设计构建了3.5GHz测量系统。测量得到的株距量由A/D转换器转换为数字信号,再由单片机进行处理,对执行末端发出指令,调整玉米收割机割台分禾器的间距,从而可以对不同株距的玉米进行收割作业。对设计的玉米收割机进行测试发现:其株距自适应能力较好,可以随株距的变化自动调整分禾器间距,玉米穗的漏采率和破碎率较低,符合高精度作业玉米收割机的设计要求,为玉米自动化收割机械装置的研究提供了较有价值的参考。     

金安桥水电站初次蓄水对导流洞稳定性影响的计算分析

金安桥水电站下闸蓄水后,陡升的库水位将对导流洞结构稳定造成不利影响。为保障堵头封堵前的导流洞结构稳定性,运用三维弹塑性损伤有限元,在模拟进水口边坡及导流洞开挖支护的基础上,计算汛前下闸水位时的岩体渗流场,对导流洞围岩和衬砌在岩体渗流作用下的结构稳定性进行复核分析。分析结果表明,导流洞的围岩稳定性在蓄水后仍有保障,衬砌结构受力较小,现有环向配筋满足结构内力要求,但在进水口变截面和导流洞变截面部位沿水流方向的拉应力较大,使得衬砌出现开裂。进一步分析表明,上述区域的开裂范围有限,对整体衬砌结构影响较小。     

乏信息材料布氏硬度测量不确定度蒙特卡罗评定

应用蒙转卡罗方法实现小样本材料布氏硬度测量不确定度的评定.依据测量误差源标定数据或布氏硬度测量结果两种数据处理途径,分析已知数据的概率分布特性,通过产生大样本量的随机数进行仿真,拓宽数据样本空间,进而分别依据不确定度合成和贝塞尔公式计算出乏信息材料布氏硬度测量不确定度.通过具体的测量实例验证了本方法的可行性.     

圆柱螺纹牙型非接触检测失真校正

在对圆柱螺纹进行非接触检测时,螺纹牙型会产生失真现象,为此提出图像校正的方法。从螺纹牙型失真的几何原理出发,建立相应的螺纹数学模型,对采集的螺纹图像进行校正,获得真实的螺纹牙型,并通过软件仿真和试验验证了该模型的正确性。同时表明图像校正的方法提高了圆柱螺纹非接触检测的精度、效率。     

红天麻箭麻发育进程中天麻素和多糖含量的变化规律研究

[目的]研究红天麻箭麻在不同发育阶段的天麻素和天麻多糖含量的相关性规律,确定其品质特征,为红天麻GAP质量控制提供科学依据。[方法]在川天麻主产区采集传统主流红天麻品系箭麻块茎样品,在原产地室内采用原位动态沙藏法贮藏箭麻;在采样后沙藏10、80、95、175和220 d分别采集天麻块茎样品,采用高效液相色谱法和苯酚-硫酸比色法分别测定天麻素含量和天麻多糖含量,并运用SPSS17.0版统计软件分析在红天麻箭麻不同发育阶段进程中天麻素和天麻多糖含量的相关性规律。[结果]川产红天麻箭麻块茎的天麻素和天麻多糖的平均含量分别为0.36%和8.17%;随着天麻沙藏休眠期-萌动期-抽茎开花-果实成熟至腐烂发育阶段进程增加,红天麻箭麻块茎的天麻素和天麻多糖含量下降,且呈极显著的负相关(P<0.001),其回归方程分别为:天麻素y1=-2E-08x3-1E-06x2-0.0001x+0.365(R2=0.996),天麻多糖y2=-5E-07x3-1E-06x2-0.008x+8.267(R2=0.996)。[结论]红天麻箭麻品质较优良,其块茎沙藏发育进程和品质下降密切相关,开花后空心和腐烂的红天麻块茎不宜作药用和制药原料。     

基于原野服务器的远程树木直径测定的研究

以卫星遥感为主的资源环境监测,由于受云层分辨率等限制,一直以来其应用重点主要在"监"上,本文介绍一种近年来刚刚兴起的能够进行远程监、控、测集网络与传感器于一身的结合体--原野服务器.首先对其定义、种类、外业设置及远程监控操作做了简单的介绍,然后尝试利用原野服务器传回的图像,通过立体视觉技术重建远隔地树木的胸径,得到了较为满意的结果,从而实现了不到现地便能够测量直径的目的.     

Simulation of soil types in Teramo province (Central Italy) with terrain parameters and remote sensing data

Soil surveys are an essential source of information for land management although a limited budget often reduces the amount of data available. Even if the dataset is limited, geostatistics can provide a valid estimation tool through a weighted moving average interpolation (kriging). Often, however, the spatial variability of soil properties appears smoothed and short range variability is underestimated by this kind of interpolation technique. A more realistic distribution of a given variable on the territory can be obtained through models based on stochastic simulation.     

中蜂越夏及秋季繁殖试验

在贵州锦屏进行的中蜂越夏及秋繁试验表明，４框以上的群势越夏较为安全。越夏期间每框足蜂约需补喂白糖１．５公斤。越夏后，蜂群群势约下降１／３左右。蜂群在越夏期间飞逃的主要原因是缺蜜及巢虫危害。当地中蜂在秋季大流蜜初期发生分蜂，分蜂群势均为８框足蜂以上，７框左右不分群。为控制不同起繁群势的蜂群在秋季大流蜜初期正好繁殖到７框左右，不致因分蜂影响秋冬蜜的采集，应分期起步秋繁。根据本试验所建秋季起繁群势（ｘ）与达７框群势所需繁殖天数（ｙ）之间的回归直线方程推算，在起繁群势为１～５框蜂量时，最适的秋繁开始期，１框群为７月３１日，２框群８月１０日……蜂群的基础群势每增加一框，则秋繁开始期应相应推迟１０～１１天。     

Current Research and Development on Deformation and Fixation of Bended Wood and Wood-based Composites

There are many advantages of bended wood,such as good-looking shape,simple process and low cost.The product,however,is easy to get recovery,which is urgent to be dealt with.This paper concludes the features of deformation and recovery of bended wood and wood-based composites and summarizes four treating methods to keep dimensional stability.Compared to bended solid wood,some elementary perspectives on the research of bended wood-based composites are presented.The purpose of this paper is to suggest:1)to investigate the optimum heating time and temperature that bended wood and wood-based composites need from the formation of deformation to the recovery and to the permanent fixation,according to its changes of dimensional stability such as curvature radius;2)to measure the composites comprised of wood and adhesives on the changes of stress relaxation,dynamic viscoelasticity and crystal1ization field;3)to quantitatively analyze changes of the major components in wood cell wall polymers as well as the composites under heat/steam treatment and untreated conditions.It will be helpful for subsequent research to clarify on the mechanisms of permanent fixation of bended wood and also contribute to that of wood-based composites.