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排序方式: 共有1384条查询结果,搜索用时 31 毫秒
31.
应用基于逼近理想解排序法的区间三角模糊多属性决策模型,对三江平原六大分区地下水脆弱性进行了风险预警和评估.评估结果与前人吻合,可为有关决策部门采取相应降低环境风险的措施提供参考.实例验证表明,模型具有更高的计算精度和更好的评价效果,为有关环境风险决策部门对地下水风险预警和评估提供了新的思路和方法. 相似文献
32.
采用双重差分模型,基于智能交通系统(ITS)效用发挥滞后时间为3年,选择2010年和2014年作为评价时点对ITS实施效果和北京交通拥堵之间的相关性进行分析.DID模型计量分析的最终结果显示,ITS效果的发挥明显改善了北京交通拥堵问题.为了验证评价结果的可信度,通过改变评价时点这一参数对评价结果进行稳健性检验,结果仍显示ITS效应发挥对北京交通拥堵改善有很大的促进作用. 相似文献
33.
HAN Tao LU XiaoChun WANG Xue RAO YongNan ZOU DeCai YANG JianFei & WU YangYang National Time Service Center Xi'an China Key Laboratory of Precision Navigation Timing Technology Chinese Academy of Sciences Graduate University of the Chinese Academy of Sciences Beijing 《中国科学:物理学 力学 天文学(英文版)》2011,(6)
With the development of Global Navigation Satellite System (GNSS),the idea of GNSS interoperability is born and has become the focus of study in the field of satellite navigation.The popularity for GNSS to augment the interoperability with the existing ones necessitates the study of the assessment algorithm of this idea.In this paper,an assessment algorithm for interoperability comprehensive benefits based on the differential equation dynamical system is discussed.There are two important aspects in GNSS tha... 相似文献
34.
局部方差在图像质量评价中的应用 总被引:4,自引:0,他引:4
将灰度图像的局部方差分布(QLS)作为表征图像结构信息的一个重要特征,对局部方差分布矩阵进行奇异值分解,计算得到相应的奇异值特征向量;通过计算降质图像与原参考图像局部方差矩阵奇异值特征向量的夹角大小度量两图像的结构相似度,实现了对降质图像的质量评价。实验结果表明:局部方差分布更能突出图像的结构特征,评价结果优于传统的均方误差(MSE)、峰值信噪比(PSNR)、结构相似度(SSIM)以及直接评价图像像素分布的奇异值分析(SVD)等方法,与人眼视觉感知效果的一致性较好。 相似文献
35.
M. Rätzsch 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(5):517-526
The investigations presented deal with the experimental results of the copolymerization of maleic anhydride (MAn) with alkenes. The course of the reaction is explained by the overall rate of the copolymerization (v Br), which correlates with the solution viscosity of the copolymer, and the dependence of the v Br maximum on the mole ratio of the monomers at constant total monomer concentration. The use of solvents with increasing donor power leads to increased complexing of the free MAn molecules and of the MAn radical chain ends. The results demonstrate that, for low 1-alkenes, the addition of the MAn chain radical is the rate-determining step of the copolymerization. As the substituents on the olefinic double bond become larger or the double bond shifts to the 1,2-position, the addition of MAn to the hydrocarbon radical becomes more and more the rate-determining step. On the other hand, an increase of the CT complexation of the MAn polymer radical by use of donor solvents decreases the alkene addition rate. 相似文献
36.
Habibu Uthman 《Journal of Dispersion Science and Technology》2013,34(4):609-615
In this work, a corrosion prediction mathematical model for risk assessment in oil and gas production and transportation facilities has been created. This work focuses on partial pressure of carbon (iv) oxide, CO2 and the operating temperature in process equipment and transportation facility pipes as a function of corrosion rate. The model equation formulated was based on the principle of multiple linear regressions of data. The final model representing the corrosion rate of crude oil equipment was obtained CR = b o + b 1 T + b 2 P (CO 2). The model was simulated using polymath software. The correlation between the experimental and simulated resulted obtained using root mean square deviation (coefficient of determination) was 99.74% which is high, suggesting that the relationship between the predictor and response variables is linear. The variation in the model equation is 0.0066374. This low value of the variance shows that the model is accurate. 相似文献
37.
V. Leoni A. M. Caricchia C. Cremisini S. Chiavarini L. Fabiani R. Morabito 《International journal of environmental analytical chemistry》2013,93(1-4):411-422
Abstract Total Diet Studies on pesticide residues in foods carried out in Italy in the last two decades are briefly summarized and data are discussed. Health risk assessment is expressed by the ratio total intake/ADI (%ADI ingested) for each compound and by the sum of the percentages of ADI for each compound within the same class of pesticides. The total dietary intake of chlorinated pesticides, that was almost 100% of ADI in the years 1970-74, decreased down to 10% in the period 1978-84. This trend was confirmed for DDT in recent years, while data on Lindane and Heptachlor seem to be constant. As regards the organophosphorus pesticides the sum of the percentages of ADI ingested for each compound, extrapolated from recent data (1990-1991) is about 20% and can be regarded as reasonably acceptable because the study included practically all the mainly used compounds. Only few data are available for some pesticides like dithiocarbamates, especially EBDCs and their derivatives (e.g. ETU), other carbamates (e.g. aldicarb), paraquat etc. Moreover, analytical methods for these compounds should be improved. The need for a considerable improvement in the number and organization of monitoring structures, in the use of standardized analytical procedures, in good laboratory practice standards and in the realibility of “monitoring protocols” and their homogeneity is evidenced. 相似文献
38.
针对仿真可视化系统开发时间长、开发费用高的问题,提出了一种利用Unity3D引擎进行实时仿真可视化系统开发的模块式设计方法。首先,对武器仿真可视化系统进行了分析,提出了智能弹药实时仿真可视化系统的五大模块;然后,通过在3ds Max下建立智能弹药模型和Unity3D下的二次开发,构建了智能弹药仿真可视化系统的仿真环境,以C#为编程工具,设计了仿真驱动、串口数据通讯和仿真输出模块;最终,实现了智能弹药实时仿真可视化系统。实验证明,该系统可以有效地在监视器上实时显示出智能弹药的飞行姿态、飞行参数和飞行轨迹。 相似文献
39.
40.
介绍了一种针对山区多样性突发火情事件中基于智能视觉的高空图像搜集系统,采用以ST意法半导体公司的STM32F107VCT6为处理核心的开发平台,地面控制平台通过高空无人机的高速照相机对目标区域火情图像数据进行搜集,并将图像数据带回到地面控制平台的PC处理器上进行综合分析。地面控制平台根据智能视觉信息采集模块采集的山区遥感图像的均值作为初始背景,并对背景图像进行实时更新,利用光谱特征与距离算法获取差分图像,并进行图像处理,从而获取山区发生火情区域的图像分析数据,以实现对山区森林突发火情事件的及时监测,在火情发生初始阶段就能扑灭。本文对山区智能视觉火情高空搜集系统的实现原理、核心硬件设计、系统软件设计等分别进行了研究,并通过系统实验进行了验证,测试结果表明,该系统在对山区的高空图像搜集实验中,对不同颜色物体的分别识别率为100%,对火灾与地形地貌的识别率为95.55%和81.12%,非常适用于各种山区环境下的智能视觉监控系统。 相似文献