试论云计算在林业信息化建设中的应用

建设现代林业是全国林业工作的主题和方向,用现代信息手段管理林业,是支撑现代林业大厦的三大支柱之一.林业信息化发展虽然已取得显著成效,但相对于其他行业而言,仍然相对滞后,要突破这个瓶颈,必须应用新技术、新方法,才能有所突破,使林业信息化上档次、上台阶.文章试论云计算在林业信息化建设中应用,以提高林业信息化建设的生态指标,...     

可控磁场磁化水处理装置的研究

为农作物浸种实验设计了一种可控磁场磁化水处理装置。装置硬件部分主要采用PWM控制方式改变电流大小,从而实现磁场大小的可控性。电压可控范围0~30 V,电流可控范围0~3 A,磁感应强度可控范围0~5 0 0 0 GS,检测显示电路可精确测量显示电压、电流以及磁感应强度的大小。用该装置产生的磁化水进行农作物浸种实验,实验结果表明:种子在使用1000 GS磁感应强度处理60min产生的磁化水浸种12小时的发芽率提高幅度最大。本装置可以满足农作物浸种实验的需求,效果较为明显。     

不同根型苜蓿苗期对干旱胁迫的生理耐受性分析

为探讨不同根系类型苜蓿对干旱胁迫的生理生化适应机制,采用盆栽模拟土壤干旱条件,以根茎型、直根型和根蘖型苜蓿为材料,测定不同根系类型苜蓿叶片相对含水量、叶绿素、可溶性糖、脯氨酸和MDA的含量及SOD活性.结果表明,不同根系类型苜蓿叶片相对含水量及叶绿素含量随干旱胁迫程度增强而降低,直根型陇东苜蓿降低程度小于其他苜蓿材料;...     

Spatial genetic diversity and interregional spread of <Emphasis Type="Italic">Puccinia striiformis</Emphasis> f. sp. <Emphasis Type="Italic">tritici</Emphasis> in Northwest China

In China, wheat stripe rust, caused by Puccinia striiformis f. sp. tritici, is one of the most destructive diseases of wheat. The Longnan and Linxia regions in Gansu Province and Qinghai Province are the major over-summering regions for the pathogen and key epidemiological zones in Northwest China. Population genetic diversity and interregional long-distance spread of the wheat stripe rust pathogen in Northwest China were studied using SSR markers. The genetic diversity in the Longnan population was much higher than those in the Linxia and Qinghai populations. Therefore, the molecular data confirmed that the Longnan region is a center of genetic diversity for P. striiformis f. sp. tritici in Northwest China. The low genetic differentiation (Gst = 0.15) and the extensive gene flow (Nm = 1.37) were found among the three regions in Northwest China. The most important conclusion of this study is that the stripe rust inoculum in Qinghai can come from both Longnan and Linxia, but mainly from Longnan directly in the spring.     

桔小实蝇热响应数学模型比较

利用恒温水浴槽对桔小实蝇的卵(16+2h)、1龄幼虫(48+2h)和非取食3龄老熟幼虫进行不同温度和时间组合的热水浸泡处理,分别利用热动力学模型、机率值模型、Logit模型和Log-Log模型对死亡率与处理时间的关系进行了分析比较,以明确最佳分析数学模型和热处理最耐受虫态。试验结果表明:热动力学模型为预测热处理致死时间的最佳数学模型;在44℃、45℃和46℃等温度条件下,桔小实蝇卵的耐热能力最强,其次为1龄幼虫,3龄幼虫耐热能力最差。该结果为利用热水浸泡处理等热处理技术对桔小实蝇进行检疫处理奠定了基础。     

路面基层材料水泥稳定沙砾抗冻性研究

水泥稳定砂砾以其强度高,板体性好以及一定的水稳定性和耐久性,广泛应用于公路路面基层,但也存在一定的抗冻性问题。以半刚性基层材料水泥稳定沙砾为研究对象,在总结国内外研究成果的基础上,通过室内试验确定不同级配的水泥稳定砂砾在不同含水量、不同温度下、经冻融循环后的耐久性。对水泥稳定砂砾的低温性能进行比较,以确定保证半刚性基层材料水泥稳定砂砾强度的最佳配合比,以期指导工程实践。     

农业固体废物分类及其污染风险识别和处理路径

防治农业固体废物污染,对保障农民身体健康,维护农业生态安全,促进农村经济社会可持续发展具有重要意义。在总结农业固体废物内涵和外延的基础上,探讨农业固体废物的主要来源、分类方法和基本特征,按照来源、毒性、组分和形态对农业固体废物进行了分类,剖析来源单一与类型多样的双重性、潜在污染与重要资源的两面性、周年持续与季节波动的复杂性等农业固体废物的基本特征。识别农业种植固体废物、畜禽水产养殖固体废物、废旧农业投入品和农产品初加工固体废物的潜在污染风险。梳理农业固体废物污染防治、处理利用代表性法规政策,分析农业固体废物全链条运营和监管体系,提出"分类处理、多措并举,统筹兼顾、绿色循环,减量回用、精准处置"的农业固体废物处理利用技术路径与模式。该研究可为指导农业固体废物污染防治和处理利用提供基础支撑和决策参考。     

Leaf resorption efficiency in relation to foliar and soil nutrient concentrations and stoichiometry of <Emphasis Type="Italic">Cunninghamia lanceolata</Emphasis> with stand development in southern China

Purpose

The relationships among resorption, leaf nutrient status, and soil nutrient availability remain unresolved. Moreover, the dynamics of resorption in leaf and soil nutrients and stoichiometry during development of Chinese fir (Cunninghamia lanceolata) stands have rarely been studied. This study quantified the resorption efficiencies of nitrogen (N), phosphorus (P), and potassium (K), and their potential correlations with stoichiometric ratios in leaf and soil as Chinese fir stands develop, and also evaluated the nutritional control on resorption in the stands based on the “relative resorption hypothesis.”

Materials and methods

Leaf and soil samples were collected from Chinese fir stands at different developmental stages (young, mature, and overmature) at the Xinkou National Forest in southern China. Samples of green leaves were collected from different portions of the crown from representative trees in different seasons. Samples of senesced leaves were collected from litter traps placed under the representative trees every month. Soils were sampled at three depths (0–20, 20–40, and 40–60 cm). Samples of green and senesced leaves were analyzed to determine nutrient (N, P, and K) concentrations, stoichiometric ratios, and resorption efficiencies. Soil samples were also analyzed for nutrient concentrations (organic matter, N, P, and K) and stoichiometric ratios.

Results and discussion

P (75 %) and K (77 %) resorption efficiencies were higher than N resorption efficiency (57 %) but did not vary among the stands. However, K resorption efficiency decreased from the young to the overmature stage. N and P resorption efficiencies were influenced by season, and leaf nutrient stoichiometric ratios varied with stand stage. Green-leaf N and P concentrations, and senesced-leaf K concentration increased with stand developmental stage. The concentrations of N, P, and K decreased with soil depth, and there was no interaction effect of stand stage and soil depth on stoichiometric ratios of the soil nutrients. The correlation results showed that nutrient resorption efficiencies were mostly affected by leaf nutrient status, but seldom by soil nutrient concentration and stoichiometry.

Conclusions

The results suggest Chinese fir might preferentially resorb P and K from senescing leaves prior to abscission. Based on the relative resorption hypothesis the Chinese fir plantations are more limited by P and that resorption may be an important mechanism to conserve nutrients in these stands in order to reduce dependence on soil nutrient pools. There is an indication that stand development affects these processes; however, the resorption process and internal mechanism need to be further investigated for the long term.

     

户用风水光直流微电网控制策略与实现

分布式能源、微电网和智能电网都是当前电力行业的热点课题。现有微电网研究集中在并网控制、潮流计算、建模与仿真、拓扑结构与控制等方面,实际投入运营的系统不多。该文在利用现有研究成果基础上,设计并研制了一套面向户用的微电网系统。该系统由风水光等电源、储能蓄电池、逆变器等单元构成,由微网调度器和远程SCADA系统进行监控和调度。通过系统分析、建模仿真和完善的功能设计,实现了智能调度与功率自动平衡、故障自愈和即插即用等功能,并在某农村投入试运行。研究成果对智能电网的智能能量管理和调度控制研究也具有借鉴意义。     

上层土壤厚度对模拟指流水分运动的影响

“上细下粗”的层状土壤中有可能产生指流,在有指流产生条件下,上层土壤的厚度是影响指流发展特征的主要因素之一。该试验通过在下层砂中模拟指流来研究上层土壤厚度对层状土壤中水分运动的影响。结果表明：指流域内的湿润锋到达一定深度的时间随着上层土壤厚度的增大而增加;稳定入渗率随着上层土壤厚度的增大而减小;并得出稳渗率和上层土的厚度呈线性关系;分别用经验函数模型和连续函数模型来模拟层状结构土壤水分的入渗,发现2种模型有各自的优缺点：经验函数模型虽然计算得到的整体误差较小,但在理论上不能很好的解释层状土壤水分入渗过程;连续函数模型相比较经验函数模型的缺点在试验初期误差较大,但该模型属于连续函数模型,符合实际的层状水分入渗过程。