Solar zenith angle and frequency dependence of ionosphericD-region absorption

In this paper, the results of a series of extensive measurements of multifrequency radio wave absorption in theD-region of the ionosphere during the epoch of the minium period of the solar cycle are presented. Experimental results for Udaipur, a low latitude station (24°35′N) are compared with the theoretically expected results. It is found that the experimental values of frequency indexm and cos χ indexn agree well with those obtained theoretically. The mean values ofm andn for the whole period of observation are found to be 1·76 and 1·4 respectively. The seasonal variation of the values ofm andn is also discussed.     

Characteristics of low latitude ionospheric E-region irregularities linked with daytime VHF scintillations measured from Varanasi

VHF amplitude scintillations recorded during the daytime period from January 1991 to December 1993, April 1998 to December 1999 and January 2008 to December 2008 at low latitude station Varanasi (geographic lat. = 25°15′N; long. = 82°59′E; geomagnetic lat. = 14°55′N, long. = 154°E, dip angle = 37.3°, sub-ionospheric dip = 34°) have been analyzed to study the behaviour of ionospheric E-region irregularities during the active solar and magnetic periods. The autocorrelation functions, power spectral densities, signal de-correlation times are computed to study the temporal features of ionospheric E-region irregularities linked with daytime scintillations. Derived spectral index ranges between −2 and −9. Assuming velocity of irregularities, the characteristic lengths of the E-region irregularities are estimated. We have estimated the minimum and maximum range of scale length of sporadic-E (E _s ) irregularities to be observed over Varanasi. These results are in close agreement with those reported from this latitude region.     

An automatic procedure for train speed evaluation by the dominant frequency method

This paper proposes an automatic procedure for train speed evaluation by the dominant frequency method based on the ground vibration characteristic induced by the trainload. A number of field measurements, a total of 154 runs with different train speeds of 198–303 km/h, were carried out to test the stability and accuracy of the proposed evaluation procedure. The evaluation differences of the train speed by using the opposed photoelectric sensing approaches and dominant frequency method are less than 3%, which means that the proposed procedure for automatic train speed evaluation is applicable and accurate. The advantages of the dominant frequency method for train speed calculation are in its mobility and cost-savings with regard to the installation and repair work, especially for long-term monitoring programs at elevated railway systems. Thus, the proposed procedure increases the applicability and potential of the dominant frequency method for train speed monitoring in real-time field measurement, since the evaluation work does not have to be done manually.     

高频红外法测定石墨样品中的固定碳

采用硝酸酸化处理,低温焙烧氧化除去无机碳及有机碳,样品于高频红外碳硫分析仪测定固定碳质量分数,经国家标准物质验证,测定值与标准值相符,方法精密度RSD%为0.71,检出限为0.02%,满足石墨低品位固定碳质量分数分析质量要求。     

原子吸收法测定岩石矿物中金含量

试样中的金用王水分解,泡沫塑料富集,原子吸收法测定。此法简捷快速,仪器稳定性好,准确度高。     

高频大地电磁法有限元数值模拟

由于中深度工程地球物理勘探的迫切需要,以美国EH-4电导率成像系统为代表的高频率大地电磁法,在我国地球物理勘探行业的应用越来越广泛。其勘探深度在地下1000m以内,频率范围在10Hz～100kHz。这里研究了高频率大地电磁法有限元高精度,快速数值模拟。首先利用广义变分原理推导出电磁场的有限元方程,编制了双线性和双二次插值有限元程序,并进行了层状模型的验证性计算,然后对典型地堑模型的数值模拟结果进行了分析,得出了一些有意义的结论。     

The magnetohydrodynamic nature of ionospheric wave packets excited by the solar terminator

Doklady Earth Sciences -     

频率下降率法对2011年新西兰6.3级地震液化的盲测

场地液化实时监测是减轻地震灾害的新手段,其核心是建立依据强震记录识别场地液化技术,但目前建立的方法尚不成熟,可靠性也缺少实际地震的检验。2011年新西兰地震中液化及其震害现象显著,为检测现有液化识别方法提供了条件。利用该次强震记录,采用孙锐和袁晓铭以往提出的频率下降率法对记录场地液化进行了盲测,为今后方法改进提供思路。针对震中距小于50 km的全部27条原始强震记录进行了识别,有9个场地识别为液化场地,其余为非液化场地;对两个已报道为液化的场地,频率下降率法给出了正确的识别结果;识别出的液化场地主要集中在克赖斯特彻奇市东侧Avon河两岸,这一结果与报导定性相符;发现有两个场地原始强震记录存在疑点,经处理后给出了修正结果。     

一种新的实测地层剖面绘制方法

当前常采用导线法绘制实测地层剖面,但该法常导致常规导线段在总导线方位上确定的地层边界点不是真实的边界,特别是平移导线段在实测地层剖面图上确定的地形线与岩性线之间产生了比较大的夹角。本文针对导线法绘图的这些缺陷,提出了绘制地层剖面的一个新方法——三维投影法：1）常规导线在总导线方位上确定的地层边界点为真实的地层边界位置,且三维投影法绘制的地层剖面图与总导线方位上的图切剖面一致;2）平移导线只在导线平面图中展现,而不出现于地层剖面图中,消除了地形线与岩性线之间存在夹角和平移导线处理的多解性问题。     

Interferences in the determination of mercury in mineralized samples by the wet reduction - flameless atomic absorption method

When mercury is determined by the reduction-aeration-flameless atomic absorption method the presence of appreciable copper and silver in the sample solution causes significant losses in mercury recovery. Zinc appears to have negligible suppressive effect.     

伽马能谱法测量水中226Ra最短平衡时间的确定

伽马(γ)能谱法测量水中226Ra,在制样过程中天然放射性核素衰变链遭到破坏,一般规定样品放射性平衡期为3～4周后测定。通过试验证明,样品天然放射性核素衰变链最终达到平衡的最短时间为11d,测量结果在允许误差范围内,满足测量精度。     

导线投影法实测地层剖面的误差分析及校正方法

在用导线投影法绘制实测地层剖面的过程中,由于导线总方位与实测导线方位之间存在误差,导致绘出的剖面不能真实反映被实测剖面的地形地质信息.根据现阶段野外实测地层剖面的工作方法,提出了道格拉斯-普克(Douglas-Peucker)分裂法、线性回归拟合法2种校正方法.将线性回归拟合法应用于粤西北庞西垌银(金)矿床Ⅰ号主矿体的实测剖面.     

石墨炉原子吸收光谱法测定血液中微量铅

研究了石墨炉测定血液中微量铅的适宜条件,用氘灯校正背景,磷酸二氢铵作基体改进剂,方法具有准确、快速、简便等优点,用于扬州妇幼保健院实际样品的测定,结果预示我们的环境不容忽视,血液中铅含量能够比较真实地反映生物个体受到的污染程度。     

红外碳硫分析仪测定土壤样品中的碳和硫

应用高频一红外碳硫分析仪,进行了土壤样品中碳、硫的测定,用该仪器测定土壤标准物质中碳、硫的结果与标准值符合。碳和硫11次测定的RSD分别是〈3%和〈10%。     

A new method of controlled-source frequency induction soundings

We suggest a new inversion method for frequency induction data implying the use of a new parameter, which has a simple analytical form in the case of a uniform subsurface. The new parameter is found from induction numbers measured in the field of a vertical magnetic dipole or a vertical magnetic dipole combined either with a horizontal electrical dipole or with a horizontal magnetic dipole. Compared with the classical methods, the new technique provides better resolved resistivity curves and faithful images of the subsurface at higher frequencies and smaller transmitter-receiver separations. The inversion algorithm is applied to amplitude and amplitude-phase data and provides reliable depth assignment of the detected resistivity layers in the latter case.     

Z-2700石墨炉原子吸收测定化探样品中痕量金

本文采用泡塑富集化探样品中痕量金,用石墨炉原子吸收法测定痕量金。试样经灼烧,王水密封溶矿,泡塑富集,硫脲解脱等过程进行了改进及条件控制,该方法具有检出限低,灵敏度高,操作简便,速度快,劳动强度小,适用地质化探样品中痕量金的测定。     

火焰原子吸收法测定岩石、土壤中微量银的研究

该方法是以硝硫混酸分解样品,用二苯硫脲—醋酸丁脂全量萃取测定岩石和土壤中微量银的一种较新的方法,称为火焰原子吸收分析法。本文实验研究了测定时萃取酸度、有机相与水相体积比、二苯硫脲的浓度以及硝硫混酸的用量对测定结果的影响。做了萃取分离后共存元素干扰测定。经与国家一级标准物质对比分析验证其结果与标准值相符。     

Bonding of methyl mercury to reduced sulfur groups in soil and stream organic matter as determined by x-ray absorption spectroscopy and binding affinity studies

We combined synchrotron-based X-ray absorption near edge structure (XANES) spectroscopy, extended X-ray absorption fine structure (EXAFS) spectroscopy and binding affinity studies to determine the coordination, geometry, and strength of methyl mercury, CH₃Hg (II), bonding in soil and stream organic matter. Samples of organic soil (OS), potentially soluble organic substances (PSOS) from the soil, and organic substances from a stream (SOS) draining the soil were taken along a short “hydrological transect.” We determined the sum of concentrations of highly reduced organic S groups (designated Org-S_RED), such as thiol (RSH), disulfane (RSSH), sulfide (RSR), and disulfide (RSSR), using sulfur K-edge XANES. Org-S_RED varied between 27% and 64% of total S in our samples. Hg L_III-edge EXAFS analysis were determined on samples added CH₃Hg (II) to yield CH₃Hg (II)/Org-S_RED ratios in the range 0.01-1.62. At low ratios, Hg was associated to one C atom (the methyl group) at an average distance of 2.03 ± 0.02 Å and to one S atom at an average distance of 2.34 ± 0.03 Å, in the first coordination shell. At calculated CH₃Hg(II)/Org-S_RED ratios above 0.37 in OS, 0.32 in PSOS, and 0.24 in SOS, the organic S sites were saturated by CH₃Hg⁺, and O (and/or N) atoms were found in the first coordination shell of Hg at an average distance of 2.09 ± 0.01 Å. Based on the assumption that RSH (and possibly RSSH) groups take part in the complexation of CH₃Hg⁺, whereas RSSR and RSR groups do not, approximately 17% of total organic S consisted of RSH (+ RSSH) functionalities in the organic soil. Corresponding figures for samples PSOS and SOS were 14% and 9%, respectively. Competitive complexation of CH₃Hg⁺ by halide ions was used to determine the average binding strength of native concentrations of CH₃Hg (II) in the OS sample. Using data for Org-S_RED, calculated surface complexation constants were in the range from 10^16.3 to 10^16.7 for a model RSH site having an acidity constant of mercaptoacetic acid. These values compare favorably with identically defined stability constants (log K₁) for the binding of methyl mercury to thiol groups in well-defined organic compounds.     

Nonlinear time series analysis of the ionospheric measurements

The applications of the tools of nonlinear time-series analysis to measurements obtained by digital ionosonde PARUS, created at IZMIRAN, is considered. Small-scale structure of the electron density Ne at F-region of ionosphere is examined by exploring observables of reflected high-frequency radio wave.Time series corresponding to given transmitter frequency f and virtual height h and conforming to usual, not perturbed, day ionogram are examined. Using the standard correlation algorithm, we have determined that for an embedding dimension n = 15, computed correlation dimension D2(n) reaches its saturation, D2 4.Reliability of the estimation of the correlation dimension was confirmed by applying to our sets of measurements J. Theiler's modification of standard algorithm. The test of time difference, smoothing procedure, calculation of the largest Liapounov exponent, and analysis of the surrogate data were employed in our study of data sets. Although our sets of measurements contain a significant random noise, nonlinear time-series analysis clear up, that the dynamics of unperturbed ionosphere, generating this time series, exhibits low-dimensional behavior.