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141.
Jinling Kong Xiaoming Sun Wenke Wang Dong Du Yan Chen Jing Yang 《International journal of remote sensing》2015,36(19-20):5257-5272
Suspended sediment concentration (SSC) is one of the most critical parameters in water quality and environmental evaluations. Remote sensing has the potential for monitoring the dynamics and spatial distribution of SSC efficiently. The primary objective of this study is to develop retrieval models that are reliable and sensitive to SSC levels in the Caofeidian area, a new seaport in northeast China, based on Landsat-5 Thematic Mapper (TM) images and a set of in situ data sets, including spectral reflectance data and water quality data. The study finds that the band reflectance ratio and binary combination factor (i.e. the ratio of the reflectance to the particle size) are more effective than single band reflectance, and a non-linear model is more potent than a linear model for predicting SSC in the Caofeidian waters. A quadratic polynomial regression model of the RTM3/RTM2 ratio is proposed as the optimal retrieval model after evaluating various models with respect to different sensitive factors. The accuracy of the model is acceptable with a relative error and a root mean square error of 25.35% and 7.22 mg l–1, respectively; the correlation coefficient between the observed and estimated SSCs is 0.986. This study also indicates that the band reflectance ratio and binary combination factor are effective in weakening and even partially eliminating the effects of the changes in the sediment type (i.e. particle size and refractive index). And the band reflectance ratio is more efficient. Using the proposed model and TM data, SSC levels for the entire region were estimated. Such results can serve as a baseline for future environmental monitoring efforts. 相似文献
142.
帧中继技术是一种成熟的快速分组交换技术,而ATM技术则是宽带网络的重要技术。文章讨论了实现二者互通的技术和方法,并提出了一种基于硬件查表的FROA(FRoverATM)业务实现方案。 相似文献
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144.
针对现有F5定量隐密分析方法仅考虑直方图收缩导致定量估计误差较大的问题,提出了一种新的基于多特征支持向量回归(SVR)的定量隐密分析算法.算法通过最大似然估计拟合DCT系数分布模型的参数,利用参数的相对变化量来反映嵌入机制对直方图的修改,并使用共生矩阵描述F5算法对图像像素间相关性的破坏.在确定特征与嵌入量之间的函数关系时,算法采用SVR在高维空间中进行拟合,从而估计待测图像的容量.实验表明,该算法可以对F5算法的嵌入量进行有效估计,而且估计效果要优于已有的算法. 相似文献
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146.
针对原发性头痛在我国发病率较高但诊断准确率较低的问题,提出了一种将文本化的国际头痛诊断标准转换为计算机可执行推理的临床知识建模和知识库构建方法,该方法首先将基于诊断标准绘制的诊断思维流程图转换为规范化的临床知识表达模型,再将临床知识表达模型通过规则映射技术转换为计算机推理诊断所用的规则,形成知识库。并以此为基础开发了覆盖完整头痛诊断流程的原发性头痛辅助决策系统。临床评估显示,该系统可正确识别出91.3%的偏头痛、87.2%的紧张型头痛和90.0%的丛集性头痛病人,对常见的原发性头痛具有较高的诊断准确率。 相似文献
147.
分子对接是预测蛋白质复合物的有效手段。对于分子对接算法的优化旨在加速分子对接效率,降低计算成本,以及充分发挥计算资源的利用率。本文主要采用3个方案对半柔性对接算法进行优化:(1)方案一在CPU端进行优化;(2)方案二在方案一的基础上,利用CUFFT的移植工具CUFFTW为方案一提供部分GPU并行接口;(3)方案三利用GPU并行架构,通过CPU和GPU的协同处理,利用纯并行计算接口进行优化。3种方案对PDB code分别为1PEE,1B6C,4HX3和2SNI的测试蛋白进行结合态和自由态的对接,求得的最小均方根偏差LRMSD小于5 Å,满足了复合物结构预测竞赛要求的中等精度结构标准,验证了对接结果的正确性。最后在保证结果正确性的前提下,测试了不同蛋白在不同方案下的运行速率;在保证不同蛋白对接效率相同的前提下,以1PPE为例,比较了不同方案下的对接速率。实验结果表明在同等旋转步长并保证程序运行结果正确性的前提下,最终的优化效果可提速近10倍,有效改进了半柔性对接算法的运行速率。 相似文献
148.
Tao Liu Aina He Fengyu Kong Anding Wang Yaqiang Dong Hua Zhang Xinmin Wang Hongwei Ni Yong Yang 《材料科学技术学报》2021,68(9):53-60
The harsh melt-spinning and annealing processes of high saturation magnetization nanocrystalline softmagnetic alloys are the biggest obstacles for their industrialization. Here, we proposed a novel strategy to enlarge the processing window by annealing the partially crystallized precursor ribbons via a heterostructured crystallization process. The heterostructured evolution of Fe84.75Si2B9P3C0.5Cu0.75(at.%)alloy ribbons with different spinning rate were studied in detail, to demonstrate the gradient nucleation and grain refinement mechanisms. The nanocrystalline alloys made with industrially acceptable spinning rate of 25-30 m/s and normal annealing process exhibit excellent magnetic properties and fine nanostructure. The small quenched-in crystals/clusters in the free surface of the low spinning rate ribbons will not grow to coarse grains, because of the competitive grain growth and shielding effect of metalloid elements rich interlayer with a high stability. Avoiding the precipitation of quenched-in coarse grains in precursor ribbons is thus a new criterion for the composition and process design, which is more convenient than the former one with respect to the homogenous crystallization mechanism, and enable us to produce high performance nanocrystalline soft-magnetic alloys. This strategy is also suitable for improving the compositional adjustability, impurity tolerance, and enlarging the window of melt temperature,which is an important reference for the future development of composition and process. 相似文献
149.
150.
Sing Teang Kong Hai-Shu Lin Jianhong Ching Huiqing Xie Paul C. Ho 《International journal of molecular sciences》2022,23(13)
The immediate and delayed metabolic changes in rats treated with valproate (VPA), a drug used for the treatment of epilepsy, were profiled. An established approach using dried blood spots (DBS) as sample matrices for gas chromatography/mass spectrometry-based metabolomics profiling was modified using double solvents in the extraction of analytes. With the modified method, some of the previously undetectable metabolites were recovered and subtle differences in the metabolic changes upon exposure to a single dose of VPA between males and female rats were identified. In male rats, changes in 2-hydroxybutyric acid, pipecolic acid, tetratriacontane and stearic acid were found between the control and treatment groups at various time points from 2.5 h up to 24 h. In contrast, such differences were not observed in female rats, which could be caused by the vast inter-individual variations in metabolite levels within the female group. Based on the measured DBS drug concentrations, clearance and apparent volume of distribution of VPA were estimated and the values were found to be comparable to those estimated previously from full blood drug concentrations. The current study indicated that DBS is a powerful tool to monitor drug levels and metabolic changes in response to drug treatment. 相似文献