高光谱数据与水稻指数及叶绿素密度的相关分析

分析了北京大屯科技站不稻叶面积指数（ＬＡ）、叶绿素密度（ＣＨ．Ｄ）与高光谱分辨率遥感数据在整个生育期内的变化过程。利用微分技术处理不稻群体反射光谱以减少土壤等低频背景光谱噪音的影响。通过单相关分析和逐步回归方法研究不稻ＬＡＩ、ＣＨ．Ｄ分别与光谱反射率、反射率的一阶微分光谱的相关关系,并建立预测回归方程。结果表明,微分技术能够改善数据与ＬＡＩ、ＣＨ．Ｄ的相关性,ＣＨ．Ｄ与光谱数据的相关明显优于同ＬＡ     

Numerical tools for geoscience computations: Semiautomatic differentiation—SD

This paper presents a differentiation method [referred to here as semiautomatic differentiation (SD)] based on generalization and extension of the Squire and Trapp formula for complex differentiation of real-valued functions. The performance of the generalized formulas for first-order derivatives is tested and compared with manual, automatic (AD), and finite difference (FD) techniques. My results show that, in terms of accuracy, the SD technique is competitive with AD, and in terms of implementation simplicity, it is identical to the FD method with the added advantage of being step-size insensitive and, hence, free from the step-size dilemma that plagues FD. Using central differencing in the complex plane, I extend the SD method to second-order derivatives, thus enabling approximation of the Hessians. Performance of the extension formulas is evaluated and compared with AD and FD methods. The results indicate that the differencing operation reduces the accuracy of the extension formulas by four to five orders of magnitude below that of the original Squire and Trapp formula. Nonetheless, compared to FD schemes, the SD method is six to seven orders of magnitude more accurate in all tests conducted. In addition, the extension formulas exhibit step-size (h) insensitive behavior over the entire h-range of the tests (1–10⁻³⁰), indicating high numerical stability of the schemes. I show by examples that SD provides a complete differentiation system that is computationally stable, efficient, highly accurate, and easy to implement.     

Structural mapping from high resolution aeromagnetic data in west central Arabian Shield, Saudi Arabia using normalized derivatives

Aeromagnetic data covering an area of about 40,000 km² at the west central Arabian Shield, Saudi Arabia has been collected and interpreted to provide structural map of the area. A number of normalized derivatives were used to help interpret the signature of magnetic data so that weak and small amplitude anomalies can be amplified relative to the stronger and larger amplitude anomalies. The interpretations obtained from these geophysical techniques of the field data demonstrated a strong correlation between magnetic anomalies and mapped subsurface geology. Based upon the variation in magnetic lineaments, shape amplitude, and trend structural map of the west central Arabian Shield on Saudi Arabia were obtained.     

中国沿海部分地区半褶织纹螺的毒性及毒素组成分析

为确定中国沿海不同地区织纹螺中的毒素成分,本研究在江苏省、浙江省和福建省设立了多个采样点,对采集的半褶织纹螺样品进行了毒性测试和毒素组成分析。研究结果显示,采集的织纹螺样品毒性范围为2—664MU(mouse unit)/g湿重,其中,采自江苏省连云港地区的织纹螺样品毒性远高于其它地区。应用高效液相色谱-质谱联用(high-performance liquid chromatography-mass spectrometry,LC-MS)方法对样品中的毒素成分进行分析,在各地的织纹螺样品中均检测到了河豚毒素(TTX)及trideoxy TTX、4-epi TTX和anhydro TTX等衍生物,但各种毒素成分所占的比例存在差异。自江苏省连云港市和浙江省舟山市采集的织纹螺样品中,Trideoxy TTX是主要的毒素成分,TTX和其它两种毒素成分次之;而自江苏省盐城市、浙江省宁波市及福建省宁德市和莆田市采集的织纹螺样品中,TTX的含量最高。采集自江苏省连云港和浙江省舟山市的大部分织纹螺样品中,肌肉组织的毒素含量最高,其次是消化腺组织,其余组织中的毒素含量最低。高毒性成分TTX的最高值主要出现在肌肉组织或消化腺组织中。从实验结果可以看出,各地的有毒织纹螺中毒素成分基本一致,而各种毒素成分所占的比例有一定的差异,织纹螺的毒性与高毒性成分TTX的含量有关。     

Fractional order intensity measures for probabilistic seismic demand modeling applied to highway bridges

Probabilistic seismic analysis of structures involves the construction of seismic demand models, often stated as probabilistic models of structural response conditioned on a seismic intensity measure. The uncertainty introduced by the model is often a result of the chosen intensity measure. This paper introduces the concept of using fractional order intensity measures (IMs) in probabilistic seismic demand analysis and uses a single frame integral concrete box‐girder bridge class and a seismically designed multispan continuous steel girder bridge class as case studies. The fractional order IMs considered include peak ground response and spectral accelerations at 0.2 and 1.0 s considering a single degree of freedom system with fractional damping, , as well as a linear single degree of freedom system with fractional response, . The study reveals the advantage of fractional order IMs relative to conventional IMs such as peak ground acceleration, peak ground velocity, or spectral acceleration at 0.2 and 1.0 s. Metrics such as efficiency, sufficiency, practicality, and proficiency are measured to assess the optimal nature of fractional order IMs. The results indicate that the proposed fractional order IMs produce significant improvements in efficiency and proficiency, whereas maintaining practicality and sufficiency, and thus providing superior demand models that can be used in probabilistic seismic demand analysis. Copyright © 2011 John Wiley & Sons, Ltd.     

完全正常化缔合勒让德函数及其导数与积分的递推关系

在地球重力场问题中,常用到完全正常化缔合勒让德函数及其导数、积分的递推关系。当前流行的地球扰动位模型均采用完全正常化的缔合勒让德函数,用此类模型可以高效方便计算各种扰动重力场元。随着本世纪多个新一代卫星重力探测计划成功实施,高阶或超高阶地球重力场模型的研究备受学界的关注。有关完全正常化缔合勒让德函数的递推关系对于高阶重力场模型具有特别意义。本文在前人研究的基础上,用初等微积分导出了若干新的递推关系式。同时还推导了正常化缔合勒让德函数及其导数、积分的检核式,这些检核式涉及地球位的球谐级数的数学性质。     

关于处处没有导数的连续函数求分数阶导数的例子

范德瓦尔登给出了一个著名的处处没有导数的连续函数的例子,本文求出了这个函数的分数阶导数。