煤储层等温吸附实验过程中参数敏感性分析

容量法等温吸附实验是测定煤储层吸附性和含气性的常用手段。实验装置中的参考缸体积V₁、装有样品时的自由空间体积V₂和压力表对等温吸附实验有着直接的影响,但是这三者对实验影响的程度目前还没有系统的认识。为了理清实验过程中各参数的影响和提高等温吸附实验的测试精度,基于波义尔定律建立了煤储层容量法等温吸附实验稳定性和精确性分析的数学模型,利用Matlab软件对吸附实验过程进行了数值模拟。研究表明,吸附实验的稳定性和准确性受压力表、参考缸的体积V₁和样品缸装有样品时的自由空间体积V₂的控制,压力表测量精度越高,等温吸附实验的稳定性和精确性就越好;压力表精度一定时,V₁和V₂的体积较小且匹配组合满足一定的条件,吸附实验才能达到较好的稳定性和精确性。利用优化方法得到的结果对鄂尔多斯盆地东缘韩城地区中煤阶煤储层开展等温吸附对比实验,结果表明,经过优化组合的吸附实验测试结果稳定和精度都有所提高,吸附量的最大差值为1.45 cm3/g,远低于未经过优化的实验所测吸附量的差值5.27 cm3/g。      

基于文献数量的中国城市规模分布研究

本文通过对中国知网（www.cnki.net）数据库中的论文进行题名检索,从而获取对不同城市进行研究或关注的论文数量,并通过论文的数量对中国地级及其以上的城市规模分布进行研究。本文的基本结论是基于文献数量的中国城市规模分布基本符合捷夫法则。具体结论如下：其一,由于对上海和北京进行研究的文献数量相差较小,中国城市文献规模分布呈现出较低的首位度,而习惯意义上的“北上广”处在两个完全不同的等级体系。其二,Zipf维数q整体水平小于1,表明学者对城市的研究较为分散。其三,Zipf维数q从2000年到2012年整体上呈现出不断下降的趋势,表明学者对城市的研究呈现逐步分散的过程。其四,中国地级及其以上城市文献规模的等级体系整体上呈现出从金字塔式向纺锥形结构演变,中等文献规模的城市在数量上占据多数。     

Influences of Indian Ocean interannual variability on different stages of El Nio: A FOAM1.5 model approach

Both the tropical Indian and tropical Pacific Oceans are active atmosphere-ocean interactive regions with robust interannual variability, which also constitutes a linkage between the two basins in the mode of variability. Using a global atmosphereocean coupled model, we conducted two experiments(CTRL and PC) to explore the contributions of Indian Ocean interannual sea surface temperature(SST) modes to the occurrence of El Ni?o events. The results show that interannual variability of the SST in the Indian Ocean induces a rapid growth of El Ni?o events during the boreal autumn in an El Ni?o developing year. However, it weakens El Ni?o events or even promotes cold phase conversions in an El Ni?o decaying year. Therefore, the entire period of the El Ni?o is shortened by the interannual variations of the Indian Ocean SST. Specifically, during the El Ni?o developing years, the positive Indian Ocean Dipole(IOD) events force an anomalous Walker circulation, which then enhances the existing westerly wind anomalies over the west Pacific. This will cause a warmer El Ni?o event, with some modulations by ocean advection and oceanic Rossby and Kelvin waves. However, with the onset of the South Asian monsoon, the Indian Ocean Basin(IOB) warming SST anomalies excite low level easterly wind anomalies over the west tropical Pacific during the El Ni?o decaying years. As a result, the El Ni?o event is prompted to change from a warm phase to a cold phase. At the same time, an associated atmospheric anticyclone anomaly appears and leads to a decreasing precipitation anomaly over the northwest Pacific. In summary, with remote forcing in the atmospheric circulation, the IOD mode usually affects the El Ni?o during the developing years, whereas the IOB mode affects the El Ni?o during the decaying years.     

Power law statistics of cliff failures,scaling and percolation

Large cliff failures have often been characterized by their size in terms of the horizontal eroded area at the cliff top, and the maximum local retreat of the coastline. Field studies suggest that the frequencies of these two quantities decrease as power laws of their respective magnitudes, defining two different decay exponents. Moreover, the horizontal area increases as a power law of the maximum local retreat, identifying a third exponent. This observation indicates that the geometry of cliff failures are similar for different magnitudes. It is shown that, under a ‘scaling hypothesis’, the exponents satisfy a precise mathematical relation that relates the exponent of the distributions of magnitudes of events and their geometry – a relation that could be useful to validate the analysis of field catalogs. In order to understand the observed scenario, a numerical model of rocky coast erosion is developed. Despite its minimal character, it reproduces the observed cliff failure statistics. Strikingly, the model precisely reproduces the geometric similarity of cliff failures observed in the field. These results suggest that the theory of percolation, which underlies the erosion model, can possibly be used as a guide to decipher the physics of rocky coast erosion and could provide precise predictions of the statistics of cliff collapses. Copyright © 2015 John Wiley & Sons, Ltd.     

CCD and photon-counting photometric observations of asteroids carried out at Padova and Catania observatories

We present the results of observational campaigns of asteroids performed at Asiago Station of Padova Astronomical Observatory and at M.G. Fracastoro Station of Catania Astrophysical Observatory, as part of the large research programme on Solar System minor bodies undertaken since 1979 at the Physics and Astronomy Department of Catania University. Photometric observations of six Main-Belt asteroids (27 Euterpe, 173 Ino, 182 Elsa, 539 Pamina, 849 Ara, and 984 Gretia), one Hungaria (1727 Mette), and two Near-Earth Objects (3199 Nefertiti and 2004 UE) are reported. The first determination of the synodic rotational period of 2004 UE was obtained. For 182 Elsa and 1727 Mette the derived synodic period of 80.23±0.08 and , respectively, represents a significant improvement on the previously published values. For 182 Elsa the first determination of the H-G magnitude relation is also presented.     

Multiple light scattering: mean number of scatterings and related problems

This is a discussion of V. A. Ambartsumyan’s studies of the mean number of scatterings for photons in scattering media and of further work and development in this area, especially at Ambartsumyan’s St. Petersburg school. The following questions are discussed briefly: (a) the traditional method for calculating the number of scatterings from the source function and critiques of this method. (b) The equation for the number N(τ; τ₀ ) of scatterings for a photon born at optical depth τ in a plane layer of optical thickness τ₀ and its use for calculating the number of scatterings, averaged over the entire ensemble of photons for a medium with arbitrary internal sources. These questions are first considered for the case of monochromatic scattering, and then for scattering in a spectral line with complete frequency redistribution (CFR). (c) The mean path length for a resonance line photon in a scattering medium with CFR and continuum absorption: the basic equations and asymptotic behavior of an optically thick layer. (d) A review of calculations of and in media that are so thick that the CFR approximation breaks down and the effects of partial frequency redistribution (PFR) become dominant. The presentation is at a semiquantitative level in many parts of this paper, with stress on physical significance rather than the mathematics, through the use of approximate and asymptotic solutions. Translated from Astrofizika, Vol. 52, No. 1, pp. 29–45 (February 2009).     

An Analytical Model for the Two-Scalar Covariance Budget Inside a Uniform Dense Canopy

The two-scalar covariance budget is significant within the canopy sublayer (CSL) given its role in modelling scalar flux budgets using higher-order closure principles and in estimating the segregation ratio for chemically reactive species. Despite its importance, an explicit expression describing how the two-scalar covariance is modified by inhomogeneity in the flow statistics and in the vertical variation in scalar emission or uptake rates within the canopy volume remains elusive even for passive scalars. To progress on a narrower version of this problem, an analytical solution to the two-scalar covariance budget in the CSL is proposed for the most idealized flow conditions: a stationary and planar homogeneous flow inside a uniform and dense canopy with a constant leaf area density distribution. The foliage emission (or uptake) source strengths are assumed to vary exponentially with depth while the forest floor emission is represented as a scalar flux. The analytical solution is a superposition of a homogeneous part that describes how the two-scalar covariance at the canopy top is transported and dissipated within the canopy volume, and an inhomogeneous part governed by local production mechanisms of the two-scalar covariance. The homogeneous part is primarily described by the canopy adjustment length scale, and the attenuation coefficients of the turbulent kinetic energy and the mean velocity. Conditions for which the vertical variation of the two-scalar covariance is controlled by the rapid attenuation in the mean velocity and turbulent kinetic energy profiles, vis-à-vis the vertical variation of the scalar source strength, are explicitly established. This model also demonstrates how dissimilarity in the emissions from the ground, even for the extreme binary case with one scalar turned ‘on’ and the other scalar turned ‘off’, modifies the vertical variation of the two-scalar covariance within the CSL. To assess its applicability to field conditions, the analytical model predictions were compared with observations made at two different forest types—a sparse pine forest at the Hyytiälä SMEAR II-station (in Finland) and a dense alpine hardwood forest at Lavarone (in Italy). While the model assumptions do not represent the precise canopy morphology, attenuation properties of the turbulent kinetic energy and the mean velocity, observed mixing length, and scalar source attenuation properties for these two forest types, good agreement was found between measured and modelled two scalar covariances for multiple scalars and for the triple moments at the Hyytiälä site.     

下垫面非均匀流域的幂指数TOPMODEL的模拟研究

利用取消流域土壤表层饱和导水率0K、土壤饱和导水率有效衰减系数m和地下水补给速率R为空间均匀假设的幂指数TOPMODEL,对流域水量平衡各分量进行敏感性研究试验,揭示空间非均匀性对幂指数TOPMODEL模拟结果的影响。从特定研究流域所得结果中可得的主要结论有:1)0K、m和R的空间变化对流域的逐日地表径流和基流以及逐日总径流有影响,针对设定的0K、m和R的空间变化,其中m的空间变化较明显地增加了逐日地表径流和洪峰流量。2)就设定的0K、m和R的空间变化而论,对流域多年平均年总径流以及蒸发模拟结果影响不大,但改变了径流在地表径流和基流之间的分配;其中R的空间变化影响最显著,m和0K的空间变化影响则较小。     

Effect of atmospheric humic-like substances on the enhanced dissolution of volatile organic compounds into dew water

Simultaneous sampling of chlorinated hydrocarbons (CHs) and monocyclic aromatic hydrocarbons (MAHs), potentially harmful to humans and/or responsible for the formation of ozone and secondary particles, in dew water and in the ambient air was carried out from August 2004 to July 2005 in Hino City, situated in the western part of Greater Tokyo, Japan. CHs were less contained in dew water than MAHs. Toluene (volume-weighted mean concentration, VWM: 4.77 nM) and m,p-Xylenes (VWM: 5.07 nM) except dichloromethane, which was abnormally high (VWM: 1.14 μM), were abundant among eleven VOCs determined in dew water. Chloroform, carbon tetrachloride, 1,2-dichloroethane, and benzene were not detected in dew water during the study period. Dew water contained higher amounts of VOCs than would have been expected from the ambient gas-phase concentrations and the temperature-corrected Henry's law constants. Following the determination method of humic substances in river water proposed by Hiraide et al. [Hiraide, M., Shima, T., Kawaguchi, H., 1994. Separation and determination of dissolved and particulate humic substances in river water. Mikrochim. Acta 113, 269–276], the VWM of soluble humic and fulvic acid fractions in dew water was found to be 1.00 mg/L and 0.87 mg/L (n = 20), respectively, while the VWM of particulate humic and fulvic acid fractions was found to be 0.61 mg/L and 0.42 mg/L (n = 20), respectively. Surface tension decreased with an increase in dissolved fulvic acid fraction in dew water, indicating that humic-like substances with relatively lower molecular weight, which is soluble in acid solution, could be an effective surface-active species within dew water. The enrichment factors, which were defined as the ratio of the observed VOCs concentration to the estimated, were over 10² for MAHs except for benzene and increased as the increment of total humic-like substances (HULIS) concentration (the sum of humic and fulvic acid fractions in both dissolved and particulate form) normalized by total inorganic ion concentration in dew water. Our results indicate that total HULIS in dew water could enhance the dissolution of atmospheric VOCs into dew droplets.     

纬度圈上的大地震带

叙述了2003年8月16日内蒙巴林左旗附近Ms6．2级和2004年3月24日内蒙东乌珠穆沁旗以北肘S5．9级2次地震前华北及唐山余震区的震兆信息;在“研究地段”内大地震迁移过程中的对称填补性和震情三分律在强震活动时段研究方面的普遍性。本文约定,凡符合此二者都可称为大地震带。