城市绿地园林树种叶面积指数测定方法研究——以小叶榕为例

分别采用半球面影像技术和LAI-2000冠层分析仪对华南地区最常用园林树种小叶榕(Ficus microcarpa)的叶面积指数(Leaf Area Index,LAI)进行测定、比较和分析。研究表明,2种测量仪器所测LAI值存在极显著正相关(P<0.001);用半球面影像技术测量的LAI值与冠幅、胸径和树高之间也存在极显著一元线性关系,构建回归模型分别为:LAI=0.0444Cw+1.6526,LAI=0.0088D+1.8327,LAI=0.0543H+1.6404;通过模型可估测小叶榕单株的叶面积指数,达到95%的置信区间的估测值范围。     

剪切干涉法用于测量燃烧温度的研究

将剪切干涉法用于温度场的测量,通过对干涉图像进行处理,得到了电阻丝周围温度场的分布。将高速摄影技术用于火花点火发动机燃烧过程的研究,拍摄到发动机整个燃烧室内火焰的连续剪切干涉图像,通过对图像进一步处理,可以定量得到燃烧过程中不同曲轴转角的缸内温度场。     

当代大学生思想政治教育认同实证分析

基于主体对认同对象和认知内容效果的评价角度，利用大规模问卷调查数据分析发现，当代大学生思想政治教育认同状况喜忧参半。一方面，思想政治教育对于大学生具有一定的积极影响，大学生对于相关核心思想政治观念具有较高的认同度。另一方面，大学生对于教育者的教学能力和教学效果认同度不高，思想政治理论课面临着“学生厌学、教师难教”的尴尬局面，大学生自身思想道德和政治素质不高、马克思主义信仰较为缺失。必须通过宏观、微观等多种途径以及教育者和受教育者等多方共同努力，改善大学生信仰状况及其对社会主义核心价值观的认同状况，提高其思想道德和政治素质。     

玉米粒重杂交当代杂种优势分析

通过测定123个不同玉米品种杂交当代种子及其母本、父本的百粒重和容重,分析了杂交育种对玉米籽粒的产量性状即百粒重和容重产生的优势以及其具有的超母本优势和超父本优势对玉米籽粒产量的影响。结果表明:不同玉米品种杂交当代籽粒百粒重、容重之间存在显著差异;玉米籽粒百粒重和容重杂交当代具有一定的杂种优势,既存在正向优势,也存在负向优势,以中亲优势、超亲优势均为正向优势为指标,本研究基于百粒重筛选出农单9139等21个品种,基于容重筛选出农单9080等16个品种。     

马克思主义关于人与自然关系的思想及其当代价值

在环境危机日益威胁到人类生死存亡的今天,重新审视马克思主义关于人与自然关系的思想具有重要的当代价值。     

基于仿生脱粒的鸡喙啄取玉米果穗引起籽粒离散过程分析

在先离散后脱粒工艺基础上,为探究玉米果穗的低损伤离散,该文利用玉米离散试验系统对鸡喙啄取玉米籽粒的过程进行试验研究。结果表明,鸡喙接触玉米籽粒后,籽粒离鸡喙越近,推力的水平分力越大,籽粒运动越明显,越容易从果穗上分离下来,籽粒离鸡喙越远,推力的水平分力越小,籽粒越难与果穗分离;离散过程中,籽粒遵循"组砌规律"进行力的传递,传递的范围近似为"塔形",脱离果穗的籽粒的运动类似于斜抛运动;玉米果穗在果穗切线方向上的受力最大,其次是玉米果穗轴线方向上的受力,垂直于试验台方向上的受力最小;验证试验结果:玉米果穗的平均离散率为67.53%,平均离散损伤率为0.16%,表明模仿鸡喙的离散辊对玉米果穗有较好的离散效果,且损伤率低。该研究对低损伤玉米脱粒系统的设计提供了仿生学思路。     

Evaluation of the suitability of arable fields for field trials by means of remote sensing

Summary The use of aerial photography for mapping the heterogeneity of trial fields was evaluated by comparing the pattern of infrared reflectance of a barley field with its spatial pattern for grain yield.The regression of yield on the infrared reflectance factor of barley appeared to be linear (correlation coefficient of 0.90). The high correlation encountered in this study justified the use of reflectance factors for estimating yield and it rendered aerial photography a good technique for mapping heterogeneity.Two kinds of maps were created in order to locate the heterogeneous parts of the field studied. One map was used for visualizing global heterogeneity and the other for visualizing local heterogeneity. These maps showed that trials performed on this particular field might be improved by using only parts of the field and by altering the shape of the blocks. The latter assertion was confirmed by field trials simulations.     

柳杉等种子活力射线测定研究

本文应用射线衬比造影法对柳杉等４个树种种子进行活力测定，研究出衬比造影的配套技术．根据衬比剂的渗透量．渗透部位，胚与胚乳的成像特征与玻板定位发芽对照，制定出各树种的Ｘ光片判读等级：杉木８级、马尾松６级、建柏和柳杉为７级，采用生物统计方法判定活力等级，结果表明各树种种子活力指数用Ⅰ、Ⅱ级累加，并用回归模型来计算种子活力指数，精度较高．     

Developments in the application of photography to ecological monitoring,with reference to algal beds

1. The potential for using photographic methods in ecological monitoring of intertidal rocky shores was investigated at two scales: the scale of a bay, and at sampling quadrat level. 2. The macroalgal beds at Selwicks Bay, Flamborough Head (north Humberside Coast, England) were used as a case study. 3. At each station on three 90 m transects, a photograph was taken of a 50 cm² quadrat. These images were analysed using SigmaScan? to measure the cover of algal species. These data were highly correlated with field data collected using a grid quadrat. 4. Ground techniques were developed for drawing a scaled overhead map of the bay. The potential for a quantitative survey of the extent of the algal beds using cliff top photographs was investigated. The photographs were merged, and rectified using Arc/Info? (a Geographical Information System package) to produce scaled overhead images of the bay. 5. The two complementary methods developed are suitable for involving amateur naturalists into field‐data collection. They were also designed to meet long‐term statutory monitoring requirements. They are quick, so are well suited to intertidal areas where field sampling windows are limited. In long‐term monitoring strategies, the use of photography produces interactive permanent records of the sample area for back reference. Reporting on the conservation status of sites of European interest could be greatly facilitated by such techniques. 6. There are obvious applications for overseas monitoring and base‐line surveys, which demand large data sets to be collected in limited periods of time. Copyright © 2001 John Wiley & Sons, Ltd.     

Estimating leaf area index of mature temperate forests using regressions on site and vegetation data

Canopy gap fraction and leaf area index (LAI) were measured using hemispherical photography in 91 mature forests across Switzerland, including coniferous, broadleaved and mixed stands. The gap fraction and LAI derived from five photographs per site could be reproduced with a high coefficient of determination (R² > 0.7) by regression against simple stand parameters obtained from vegetation surveys: coverages of the tree, shrub and herb layers, and tree height. The method appeared to be robust across the different types of forests. Applied to 981 sites across Switzerland, the regression model produced LAI values ranging from 1.4 to 6.7. These predictions were compared with site variables not included in the regression. LAI appeared limited by the altitude, with maximal values decreasing by one third from 400 to 2000 m above see level. Water availability was also clearly a limitation at sites with a negative water balance, i.e. where the yearly potential evapotranspiration exceeded the precipitation. High or low values of a humidity index based on the ground vegetation also corresponded to a limitation of the LAI, with shorter trees at dry sites and more open canopies at wet sites. Compared to optical measurements (including hemispherical photography), our regression method is fast and inexpensive. Such an approach appears very promising for obtaining reliable estimates of LAI for many sites with low costs. These estimates can then be fed into process models at the stand level.