试用三维地形模式计算茂密林区火险等级   总被引：2，自引：0，他引：2  

钱锦霞  张洪涛 《山西气象》2001,(3):15-17

本文用考虑森林植被的三维地形模式，对1972年4月15日神逐架林区森林火灾发生期间的风场、温度场和相对湿度场等进行了模拟，并在此基础上计算森林火险等级。结果表明，采用数值模拟方法可以得到无测站地区的气象要素，为进行森林火险等级预报奠定了基础。  相似文献   

测井评价稠油层等级的新方法   总被引：1，自引：0，他引：1       下载免费PDF全文

谭廷栋 《地球物理学报》1992,35(6):781-789

从测井信息中提取油和水的重量百分比,最能反映稠油层质量的特征.用油和水的重量百分比评价稠油层等级,是一种新概念.测井评价稠油层等级的新方法,就是根据这一新概念建立的.本文论述了新方法的物理基础,建立了测井评价稠油层等级的数学公式,并且给出了评价法则和应用范例.  相似文献   

模式识别与成矿预测Ⅳ——Isokid模式识别方法及其在矿产预测中的应用     

张景廉  叶伟龙 《铀矿地质》1990,(2)

在Isodata、Isomix等方法的基础上,笔者提出一个新的非监督模式识别方法即Isokid算法,该法还吸取了Cora-3、Hamming等监督模式识别方法的一些特点,使它具有很多优点:(1) 简化了初始聚类中心的计算;(2) 利用信息量计算法给特征加权;(3) 采用了删除特征试验;(4) 适用于多类分类识别。本文以广东花岗岩型铀矿床的识别预测和对赣中南产铀、产钨岩体的识别为例,介绍了本方法的使用情况和特点。结果表明,本方法识别结果可靠稳定,是目前模式识别中较好的方法,除应用于地质找矿外,还可应用于其它领域。  相似文献   

Interactions between a cyanobacterial bloom (<Emphasis Type="Italic">Microcystis</Emphasis>) and the submerged aquatic plant <Emphasis Type="Italic">Ceratophyllum oryzetorum</Emphasis> Kom.     

李敦海  李根保  陈武雄  刘永定 《中国海洋湖沼学报》2009,27(1):38-42

In aquatic ecosystems, macrophytes and phytoplankton are main primary producers, in which macrophyte plays an important role in maintaining clear water state, while phytoplankton often dominates in turbid waterbodies. In the present study, the growth and photosynthetic activity of the submerged aquatic plant Ceratophyllum oryzetorum Kom. in different cell densities of cyanobacterial bloom are studied. The results show that the plant length and fresh mass of C. oryzetorum are promoted by low cyanobacterial cell densities. Medium and high cyanobacterial cell densities, on the contrary, act as inhibitory. Furthermore, the photosynthetic activity of C. oryzetorum is strongly inhibited by high cyanobacterial cell densities. To a certain extent, the growth of cyanobacteria is inhibited by C. oryzetorum, but no significant effect is found in this study. Supported by the Innovation Project of CAS (No.KZCX2-YW-426), a Provincial Project of Hubei (No. 2006AA305A0402) and the National Basic Research Program of China (973 Program, No. 2002CB 412306)  相似文献   

Screen and effect analysis of immunostimulants for sea cucumber, <Emphasis Type="Italic">Apostichopus japonicus</Emphasis>     

李继业  孙修勤  郑风荣  郝林华 《中国海洋湖沼学报》2009,27(1):80-84

Immunostimulants may improve disease resistance of aquaculture animals by promoting the nonspecific immunity response of the organisms. Five types of saccharides, including chitosan, yeast polysaccharide, burdock oligosaccharide, seaweed polysaccharide and lentinus edodes polysaccharide, were screened for potential use as immunostimulants by using spectrophotometry. The saccharides were injected into Apostichopus japonicus, a sea cucumber, and the lysozyme and superoxide dismutase (SOD) activities of the coelomic fluid and epidermal slime were monitored in six consecutive days. The results show that the lysozyme activity of the animal’s coelomic fluid was significantly stimulated on day 2, day 4 and day 6 after the injection of the saccharides (P<0.05). The effects of chitosan and yeast polysaccharide were the most notable. The lysozyme activity of the epidermal slime was significantly increased by chitosana, yeast polysaccharide, seaweed polysaccharide, and burdock oligosaccharide on day 1 and day 2 after the injection (P<0.05). The SOD activity of the coelomic fluid was significantly promoted by the saccharides on day 2 and day 4 post-injection (P<0.05), while the SOD activity of the epidermal slime increased on day 2. These findings indicate that chitosan and yeast polysaccharide are the most effective immunostimulants and potential healthy anti-disease feedstuff for A. japonicus. Supported by the National Key Technology Research and Development Program (863 Program, No. 2006BAD09A06) and the Special Fund of Chinese Central Government for Basic Scientific Research Operations in Commonweal Research Institutes (No. 02-2007B03)  相似文献   

约束Delaunay三角剖分的“岛屿”类图斑符号填充     

毛文山  刘涛  杜萍 《测绘通报》2020,(6):32

针对传统方法对“岛屿”类图斑进行符号填充会造成敏感区域符号布局不合理或符号空间冲突的问题，本文提出了一种约束Delaunay三角剖分的“岛屿”类图斑符号填充方法。首先，对“岛屿”类图斑对应的离散点群进行规则网格化和不规则三角剖分，用于计算等值点；然后，依据附加准则增加“凸”形和“凹”形附加点，顺次连接等值点和附加点作为Delaunay三角剖分的约束边界；最后，构建均匀变化的约束Delaunay三角网，在三角网内进行图元积分，填充“岛屿”类图斑符号。利用电子海图中岛屿边界点数据进行试验分析，与传统方法相比，本文方法填充的“岛屿”类图斑符号变化均匀，交互性较强，便于用户修改和切换，进行二次填充。试验结果表明，本文方法适用于“岛屿”类图斑的符号填充。  相似文献   

图像预处理对人脸识别系统性能影响研究     

金欣  文成玉  杜鸿 《成都信息工程学院学报》2015,30(2)

目前多数工程化人脸识别系统是基于子空间算法的,针对子空间算法识别系统中稳定性和抗干扰性不高的问题,从图像预处理的角度出发,通过Matlab仿真Eigenface和Fisherface两种算法识别过程,建立起图像差值模型,同时引入不同预处理方法进行比较,根据类间距离和类内距离的变化,从中确定出最优的预处理方法,改善算法识别率和效率,实验结果表明,加入合适的图像预处理可以增强识别系统的强壮性.  相似文献   

Perihelion motion of small irregular dust particles due to radiation forces     

J. Kla?ka  F. Kundracík 《Planetary and Space Science》2006,54(4):379-393

Perihelion motion, i.e. a secular change of longitude of perihelion, of interplanetary dust particles is investigated under the action of solar gravity and solar electromagnetic radiation. As for spherical particle [Kla?ka, J., 2004. Electromagnetic radiation and motion of a particle. Cel. Mech. Dynam. Astron. 89, 1-61]: (i) perihelion motion is of the order ( is heliocentric velocity of the meteoroid and c is the speed of light in vacuum), if a component of electromagnetic radiation acceleration is considered as a part of central acceleration; (ii) perihelion motion is of the first order in if the total electromagnetic radiation force is considered as a disturbing force. The new facts presented in this paper concern irregular dust particles. Detailed numerical calculations were performed for the grains ejected at aphelion of comet Encke. Perihelion motion for irregular interplanetary dust particles exists already in the first order in for both cases of central accelerations. Moreover, perihelion motion of irregular particles exhibits both positive and negative directions during the particle orbital motion. Irregularity of the grains causes not only perihelion motion, but also dispersion of the dust in various directions, also normal to the orbital plane of the parent body.  相似文献   

Equilibrium trading of climate and weather risk and numerical simulation in a Markovian framework   总被引：3，自引：3，他引：0  

Sébastien Chaumont  Peter Imkeller  Matthias Müller 《Stochastic Environmental Research and Risk Assessment (SERRA)》2006,20(3):184-205

We consider financial markets with agents exposed to external sources of risk caused, for example, by short-term climate events such as the South Pacific sea surface temperature anomalies widely known by the name El Nino. Since such risks cannot be hedged through investments on the capital market alone, we face a typical example of an incomplete financial market. In order to make this risk tradable, we use a financial market model in which an additional insurance asset provides another possibility of investment besides the usual capital market. Given one of the many possible market prices of risk, each agent can maximize his individual exponential utility from his income obtained from trading in the capital market, the additional security, and his risk-exposure function. Under the equilibrium market-clearing condition for the insurance security the market price of risk is uniquely determined by a backward stochastic differential equation. We translate these stochastic equations via the Feynman–Kac formalism into semi-linear parabolic partial differential equations. Numerical schemes are available by which these semilinear pde can be simulated. We choose two simple qualitatively interesting models to describe sea surface temperature, and with an ENSO risk exposed fisher and farmer and a climate risk neutral bank three model agents with simple risk exposure functions. By simulating the expected appreciation price of risk trading, the optimal utility of the agents as a function of temperature, and their optimal investment into the risk trading security we obtain first insight into the dynamics of such a market in simple situations.

Peter ImkellerEmail:

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A Statistical Analysis of the Theoretical Yield of Ethanol from Corn Starch   总被引：1，自引：1，他引：0  

Tad W. Patzek 《Natural Resources Research》2006,15(3):205-212

  This paper analyzes the Illinois State Variety Test results for total and extractable starch content in 708 samples of 401 commercial varieties of corn. It is shown that the normally distributed extractable starch content has the mean of 66.2% and the standard deviation of 1.13%. The corresponding maximum theoretical yield of ethanol is 0.364 kg EtOH/kg dry corn, and the standard deviation is 0.007. In the ethanol industry units, this yield translates to 2.64 gal EtOH/nominal wet bushel, and the standard deviation is 0.05 gal/bu. The U.S. ethanol industry consistently has inflated its ethanol yields by counting 5 volume percent of # 14 gasoline denaturant (8% of energy content) as ethanol. Also, imports from Brazil and higher alcohols seem to have been counted as U.S. ethanol. The usually accepted USDA estimate of mean ethanol yield in the U.S., 2.682 gal EtOH/bu, is one standard deviation above the rigorous statistical estimate in this paper.

Tad W. PatzekEmail:

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