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数字化地震记录波形线性度的分析处理方法及其初步应用

探讨了数字化地震记录P 波初始部分波形线性度的两种分析处理方法,即波形的时间线性度和波形的空间线性度的分析处理方法,并着重介绍了这两种方法在地震预报研究中的初步应用结果.     

On incremental non‐linearity in granular media: phenomenological and multi‐scale views (Part I)

On the basis of fundamental constitutive laws such as elasticity, perfect plasticity, and pure viscosity, many elasto‐viscoplastic constitutive relations have been developed since the 1970s through phenomenological approaches. In addition, a few more recent micro‐mechanical models based on multi‐scale approaches are now able to describe the main macroscopic features of the mechanical behaviour of granular media. The purpose of this paper is to compare a phenomenological constitutive relation and a micro‐mechanical model with respect to a basic issue regularly raised about granular assemblies: the incrementally non‐linear character of their behaviour. It is shown that both phenomenological and micro‐mechanical models exhibit an incremental non‐linearity. In addition, the multi‐scale approach reveals that the macroscopic incremental non‐linearity could stem from the change in the regime of local contacts between particles (from plastic regime to elastic regime) in terms of the incremental macroscopic loading direction. Copyright © 2005 John Wiley & Sons, Ltd.     

用BP网络求解土体的导热系数

以人工神经网络为基本工具,利用其强大的非线性映射能力,综合考虑土体的物理性质指标对其导热性能的影响,为求解土体的工程参数提供了一条新的途径。结果表明,ＢＰ网络能够充分体现土体物理指标之间的非线性关系和隐含关系,具有较高的求解能力,所求出的土体的导热系数与实测值接近,其精度远高于线性回归,且简单实用。     

多目标无人机微型凝视高光谱成像仪辐射校正

微型凝视高光谱成像仪可以同时获取两个空间维度和一个光谱维度图像,且仅记录整个高光谱图像的外方位元素而不是记录每一帧图像的外方位元素,避免了扫描时的几何不稳定性,有效解决了小型线扫式高光谱成像仪成像几何变形大的问题,适合于姿态不稳定小型无人机负载平台。目前,研究大多集中于线扫式高光谱成像仪辐射校正方法。凝视型高光谱成像仪应用时间较短,国内外没有较为成熟的数据处理研究,阻碍了无人机微型凝视高光谱成像系统的应用。本文研究了无人机载微型凝视高光谱成像仪辐射响应线性度特性和辐射响应变异性的校正方法,并定量评估该方法的有效性。结果表明,辐射响应变异性校正前,高光谱图像存在明显的渐晕效应和条带现象,校正后,不同波段中像元的辐射响应变异系数显著下降,且渐晕效应和图像条带明显减少。本文提出了基于多目标辐射定标方法,并通过比较定标后的高光谱图像光谱与地面光谱仪实测地物光谱来验证辐射定标的精度。结果表明,多目标辐射定标方法的定标结果表现出更好的效果,特别对于近红外波段,与光谱仪实测的地物反射率差异较小。     

Re-evaluation of linearity and precision of Gas Bench II-IRMS system and potential implications for carbon and oxygen isotope measurements on small-sized carbonate samples

In this study, the δ^13C and δ^18O values were systematically measured on NBS-18, NBS-19 and IAEA-CO-1 with different sample sizes, with the objective to examine the stability and reproducibility of previously developed linearity correction strategy especially for small-sized samples （e.g. 〈50 μg）. Firstly, the δ^13C and δ^18O values of NBS-19 standards （6-10 samples per run） with sample sizes scattered below -100 μg were determined in three different runs. The logarithmic regressions were performed on the plots of δ-values vs. peak area （sample size） for each run and the correction was applied using peak area of the first peak. Results show that two of the three data sets have almost the same regressive equations for both δ^13C and δ^18O values. The maximum difference in δ^13C values calculated by three equations when sample size varies between -10 and -100 μg is better than 0.15‰, compared with the maximum 0.82‰ for δ^18O values. Since alteration of phosphoric acids could not influence carbon isotope, the 〈0.15‰ difference in calculated δ^13C values should reflect the stability of mass spectrometer conditions. In contrast, the large difference in regressive equations for δ^18O values may be attributed to changed oxygen isotope in phosphoric acids due to exchange with atmosphere through time. It means that standards with sample sizes properly distributed should be arranged in every run for subsequent linearity correction of δ^18O values of small-sized samples （e.g. marine ostracode）.     

分段回归在剔除精河、库尔勒水平摆气象因素影响的探索

以精河、库尔勒水平摆观测数据为因变量,以地温、气温、气压为自变量进行分段回归分析,结果如下:(1)地温和气温是影响精河、库尔勒水平摆观测数据年频段信息的主要因素,它们之间具有准线性关系;(2)去掉趋势后,观测数据与地温、气温、气压之间的线性相关性明显增强,说明观测数据的趋势转折变化不是气象因素造成的,可能是观测区域的构造应力变化所致;(3)研究表明分段回归是全样本回归分析方法的一种改进,是降低时间序列数据处理难度的有效方法。     

大气温度对斜拉桥主梁线型影响探讨

介绍斜拉桥主梁施工中，大气温度对主梁线型的影响规律，提出了一些有用的结论和建议。     

地震波时间线性度在安徽及邻区中强震中短期预报中的应用研究

应用地震波波形时间线性度方法 ,对安徽及邻区二次中强震前后及近 8年来本省多台地震波资料 ,进行了时间线性度 r值及其初始部分振动的平均半周期 Th 值分析研究。结果认为 :1本省及邻近区域中强震前 ,震中一定范围内存在着 r值和 Th 值低值异常现象 ,异常持续时间一般在 4～ 1 2个月 ,异常恢复后至主震发生时间一般在 0～ 1 2个月内 ;2震前 r值和 Th值的异常变化 ,实际上反映的是区域应力场的调整变化     

变基床系数弹性地基梁解法及其应用

从实测的P-S曲线（基地压力与沉降的关系）出发,将P-S曲线拟合成分段线性函数,把分段线性函数的斜率作为基床系数,推导出变基床系数弹性地基梁的基本理论方程式,并将它变换成与常基床系数弹性地基梁相同的方程形式,从而,可以用初参数法解出它的一般解。此方法可以推广到变截面梁和非均质地基的情况。