共查询到19条相似文献,搜索用时 234 毫秒
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提出了一种以样品光谱类间相关系数之和最小为准则进行光谱波长逐步筛选的方法(stepwise selection basing on minimum sum of correlation coefficients, SMCC),以类间距离与类内距离和的比值最大化(符合分析者主观预期目标)作为定性分析中特征波长筛选效果的评价依据,并使用红塔集团提供的2012年17种不同类型工业分级烟叶作为试验样品,以验证筛选方法的有效性。研究表明,采用CO1分级烟叶光谱作为参照类别,筛选出10个特征波长点:采用特征波长计算得到的类内欧氏距离的平均值为采用全部波长计算得到的平均值的1.69倍,采用特征波长计算得到的类间欧氏距离的平均值为采用全部波长计算得到的平均值的3.70倍,采用特征波长计算得到的类间欧氏距离与类内欧氏距离和的比值的平均值为采用全部波长计算得到的平均值的2.21倍。特征波长的类间与类内欧氏距离和的比值增大,说明筛选出来的特征波长能更加有效的表达不同类间的远近关系以及同一类内的离散度,SMCC算法是一种有效的、可应用于近红外光谱定性分析中的特征波长筛选方法。 相似文献
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提出了用于TEXONO实验中双端读出的长柱形CsI(Tl)闪烁晶体探测器的两种粒子能量重建方法———“算术平均值能量重建法”和“几何平均值能量重建法”,讨论了两种算法的理论依据和计算方法,并对两种算法进行了比较 相似文献
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提出了用于TEXONO实验中双端读出的长柱形CsI(T1)闪烁晶体探测器的两种粒子能量重建方法——“算术平均值能量重建法”和“几何平均值能量重建法”,讨论了两种算法的理论依据和计算方法,并对两种算法进行了比较。 相似文献
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基于均值距离测度的医学图像配准 总被引:4,自引:3,他引:1
针对互信息测度在配准医学图像时易陷入局部极值、速度慢的缺点,提出了基于均值不等式的均值距离测度.首先根据均值不等式推导出5种均值距离测度:方根-算术均值距离(SAM)、方根-几何均值距离(SGM)、方根-调和均值距离(SHM)、算术-几何均值距离(AGM)、算术-调和均值距离(AHM).然后通过人体脑部CT/MR和MR-T1/PD图像的刚体配准实验,从函数曲线、配准精度、计算时间和收敛性能方面,对互信息与5种均值距离信息测度进行了比较与分析.实验结果表明,在不损失配准精度的前提下,AHM和SAM测度可以获得更快的配准速度,对噪声有很强的鲁棒性. 相似文献
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导航系统中广泛采用激光测距确定星地间距离,双向反射分布函数可精确描述实际物体反射光的情况,是研究激光测距方程的有效手段。结合目标反射几何模型,计算得到透镜各点接收目标反射光强的表达式。对目标光斑和接收透镜进行网格划分,仿真得到透镜面元接收目标反射的光强分布和透镜接收的瞬时光强,并讨论了平面目标的网格步长选取和计算次数。当光束从不同空间位置入射至平面目标表面时,根据探测器-反射棱镜之间距离与接收光强的对应关系得到激光测距方程的待定参数。实测数据验证了理论计算的正确性。 相似文献
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在统一展开理论的框架内,通过提高推导过程中的精度,得到了更精确的结果,且将其推广应用到激光系统中。具体研究两个激光模型,得到了它们的光强定态几率分布、光强平均值及相相对涨落,通过比较发现,本文所得到的结果明显的改善了用统一色噪声的似所得到的结果而与精确的数值结果和数值模拟结果符合更好。 相似文献
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Effect of road structure on the capacity of a signalized road intersection 总被引:2,自引:0,他引:2 下载免费PDF全文
In this paper, we use the stochastic Nagel--Schreckenberg (NaSch)
model to investigate the influence of a special right-turning lane
connecting two main roads on the capacity of a signalized road
intersection. It is found that the magnitude of right-turning
traffic flow and the linking position of the special right-turning
lane can greatly influence the capacity of the signalized road
intersection. The relation between traffic flow and entering
probability for different distances between the entrance (exit) of
the special right-turning lane and the road intersection is
simulated and analysed. The corresponding spatiotemporal pattern and
phase diagram on different sections of the main road are given
under the condition of close proximity to the signalized road
intersection, stop-and-go traffic occur and obstruct the
intersection. On the contrary, unchanged flux is maintained as the
distance exceeds a critical values. All the studies indicate that
setting a special right-turning lane by choosing a suitable location
near a signalized road intersection can relieve the load of current
traffic on the main road and maintain traffic flow. 相似文献
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None of the existing standards, which express the needs of engineers, consider correlation properties of traffic noise. But the correlation properties of traffic noise often seem to have a fundamental importance in certain engineering fields of noise control, such as the design of barriers for sound insulation and the detection of voices in noisy out-of-doors situations. In this paper, firstly, the correlation properties in the time domain and the frequency characteristics of the sound intensity at an observation point are discussed in the general case: i.e., for arbitrary values of quantities such as the propagation characteristics of the traffic sound energy, the numbers of lanes of road and of types of vehicles, the mixture ratios of vehicle types, the average number and respective acoustic power distributions of vehicles travelling with specific velocities on each lane of the road, the lengths of the straight sections of the road and the distance from the observation point. Next, the equivalence problem of replacing the several lanes of the road by a representative single lane is also discussed in detail, as an application of the statistical method. Finally, the values obtained from the theoretical expressions for several kinds of correlation functions of lower and higher orders are compared with experimental values, as obtained by use of the digital simulation technique. 相似文献
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基于算术-几何均值距离的多模态图像配准 总被引:4,自引:1,他引:3
根据图像灰度联合概率分布函数与图像相似程度之间的关系,提出了一种基于算术 几何均值距离的多模态图像配准新测度。与基于信息论的测度不同,新测度不再要求概率分布必须满足连续性的要求。实验结果表明,所提出的新测度比基于信息论的测度具有更强的噪声鲁棒性和计算量更小。 相似文献
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In this study, we introduce outdoor sound simulation that is fully compliant with ISO 9613 yet with some complementary methods that enhance its applicability; for example, calculation of sound attenuation due to undulating terrain in octave bands, geometric divergence in the near-field of the source, and short-term wind effects. Using the method, we have carried out highway traffic noise prediction and measurement for 12 sites with representative road shapes and structures. In the prediction, the sound power level for a road segment was estimated by the method suggested in ASJ Model-1998 with experimental corrections to the overall noise level and spectrum. Comparing results between predicted and measured noise levels show good correspondence at direct, diffracted and reflected sound fields within 30m from the center of the near side lane. 相似文献
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The adequacy of a model for the sound level close to a road is investigated by comparing resulting predictions for the sound level over a building façade with measurements. The road model involves the road geometry (the number and positions of traffic lanes), the traffic structure (vehicle flow rates and their average speeds in each lane) and equivalent omnidirectional point sources representing the vehicles. It is found that the assumed road traffic noise source model is adequate only for predicting levels over the higher part of the façade. However the investigation has allowed definition of what improvements are needed in the road source modelling to enable adequate predictions over the whole of the building façade. 相似文献
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应用线性组合算符和幺正变换方法,研究磁场和耦合强度对极化子有效质量和平均声子数的影响.数值计算表明:极化子的有效质量随耦合强度的增加而增加,这是由于耦合强度增加时,电子与晶格振动之间的相互作用增加所致;而磁场强度增加时,有效质量是先增加,达到一个极大值后,再逐渐减少,出现共振现象.平均声子数随耦合强度的增加而增加,当磁场强度大于共振时的磁场强度时,随磁场强度的增加而减少,反之,结论相反. 相似文献
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A new method to determine the minimum measurement time interval needed to obtain the equivalent continuous A-weighted sound pressure level with a designated reliability is presented. This method considers variations in the noise emission from passing vehicles. To verify the validity and availability, simulation experiments based on our dynamic model are examined under various traffic conditions. A statistic quantity, the mean time interval between two maximum sound pressure levels consecutively observed during the reference measurement time interval, is introduced in the experimental analysis. Additionally, the theoretical analysis includes another statistic quantity corresponding to the mean time interval, the mean recurrence time of the maximum sound pressure level, when the transition probability, rate of heavy vehicles, and probability distribution of vehicles passing the observation point during the reference measurement time interval are known. 相似文献