现有波群因子的统计研究

自Goda于1970年提出谱峰度参量Qp以来,迄今表征波群强度的因子己有十多种.对文中提及的较常用的11种因子即以后被称为现有波群因子,各作者都强调自己的优点,但何者为较好,直至目前尚无客观的评价.依据从三个测点获得的111组数据对现有波群因子予以检验,若某一因子在较短的记录长度内有连续三个值且其中最大值和最小值满足:(最大值减最小值)不大干0.005,则被称为稳定的波群因子;若这种因子又满足三个条件,即它在任一序数中出现的次数最多、在整条记录中出现的总次数最多和在整条记录的最初1280s内出现率最大,则被称为较佳波群因子.就检验的个例而言,(波高的)平均连长(L₁)和波高与周期的相关系数［R_HT(0)]就是这种因子.将这两个因子连结起来,今后称之为联合波群因子.因此,建议以此联合波群因子表征波群强度将会较前人采用的单因子的为好.     

气象科技期刊2001—2007年主要评价指标分析

为客观定量地了解目前气象科技期刊的学术水平现状,促进气象科技期刊的发展,依据学术期刊综合评价指标,对2001—2007年气象科技期刊的影响因子、5年影响因子、即年指标、被引半衰期、Web即年下载率以及网络传播趋势等进行统计对比分析,得出了相关结论。     

Chemical composition of wet and dry atmospheric depositions in an urban environment: local,regional and long-range influences

The results of a 8 year survey of wet and dry depositions collected in Bologna (Northern Italy) are presented and discussed: monthly fluxes of the main ions (hydrogen, sodium, potassium, calcium, magnesium, ammoniacal and nitrate nitrogen, sulphate and chloride) have been registered and statistically discussed. The trend of hydrogen ion, whose largest correlation in the global deposition was found with sulphate, is clearly downwards, with peaks mainly in winter months. By means of a data factor analysis, three main sources to explain the variability of the deposition chemistry were recognized: an anthropogenic contribution (particularly represented by NO₃ ⁻, SO₄ ²⁻, H⁺), the sea spray (Na⁺, Cl⁻ and, to a lesser extent, K⁺ and Mg²⁺) and a terrigenous fraction, particularly characterized by higher Ca²⁺ concentration; however, some concentration peaks of this ion have been found in association with some episodes of Saharan dust transportation.     

Determination of the critical failure surface for slope stability analysis using ant colony optimization

Slope stability analysis of any natural or artificial slope aims at determining the factor of safety of the slip surface that possesses the lowest factor of safety. In this study, an ant colony optimization (ACO) algorithm is developed to solve this factor-of-safety minimization problem. Factors of safety of slip surfaces are found by using the Morgenstern–Price method, which satisfies both force and moment equilibrium. Nonlinear equations from the Morgenstern–Price method are solved numerically by the Newton–Raphson method. In the proposed ACO algorithm, the initiation point and the shape of the slip surface are treated as the search variables. The proposed heuristic algorithm represents slip surfaces as piecewise-linear curves and solves for the optimal curve yielding the minimum factor of safety. To demonstrate its applicability and to investigate the validity and effectiveness of the algorithm, four examples with varying complexity are presented. The obtained results are compared with the available literature and are found to be in agreement.     

Geochemical investigation and characterisation of Neogene sediments from Valjevo-Mionica Basin (Serbia)

Sediments from the Valjevo-Mionica Basin of Neogene age were investigated in this study using different geochemical methods. The results of the inorganic part analyses suggest that during genesis of the sediments, the contents of Na₂O, B and As changed the most, which indicates that genesis of the investigated sediments was followed by climate changes and volcanic activity. The quantity of other macro- and microelements did not vary significantly. Investigations of the organic substance showed that it is native organic matter, which has been preserved to a significant extent, formed predominantly of algal precursor organisms, which provided good quality, deposited under reducing conditions and that it is at a low maturity level. As it has been established that genesis of the investigated sediments was mostly affected by an arid climate with more intensive salinity, the aim of this study, was also to identify the processes which were the most affected by the change in salinity, as well as biomarkers which are the most sensitive to this change. The results led to the conclusion that the salinity increase in the depositional environment had a primary effect on the preservation of the organic substance and the formation of the mineral searlesite. In addition, it was noticed that besides the Sq/nC₂₆ ratio, the parameters nC₁₇/nC₂₇, CPI and Ph/nC₁₈, are also significantly sensitive to salinity change in a depositional environment in case of immature organic substance deposited under reducing conditions.     

范数灰关联度分析法在灌浆加固工程中的应用

基于范数概念计算的灰关联度较常用的基于均值思想计算的灰关联度具有更好的整体接近性,本文将范数灰关联 度分析法引入到灌浆加固工程中,应用于确定影响单位深度吸浆量因素的权重上。计算实例表明,该方法具有较高的准确性 和可操作性,能方便、快捷、较准确地确定影响地基单位吸浆量的因素权重。     

Determination of mineralization stages using correlation between geochemical fractal modeling and geological data in Arabshah sedimentary rock-hosted epithermal gold deposit,NW Iran

This research paper aims to delineate and recognize different gold mineralization stages based on surface lithogeochemical data using factor analysis and Spectrum-Area (S-A) modeling, as well as geological data in Arabshah sedimentary rock hosted epithermal gold deposit, NW Iran. Based on the factor analysis, Au and Mn were allocated to factor 2 (F2) and then classified by the S-A fractal modeling. In addition, Au and F2 values were transformed to spectrum data, which were categorized by the S-A log-log plots. Accordingly, the main mineralization phase contains Au and F2 (Au-Mn) values greater than 800 ppb and 0.3, respectively, and is associated with the occurrence of minerals such as pyrite, arsenian pyrite, realgar, orpiment and oxidized sulfides. The first phase of gold mineralization, where Au typically ranges between 80 and 350 ppb, is associated with base metal sulfides, arsenian pyrites and F2 values between 0.1 and 0.2. The second gold mineralization phase consists of Au values from 350 to 800 ppb and F2 values between 0.2 and 0.3. Combination of the S-A modeling, factor analysis and geological data outlined three gold mineralization stages in Arabshah gold deposit. The main mineralization stage showed a strong positive correlation with the NE-SW and NW-SE trending structures, the altered intrusive rocks such as microdiorite and granodiorite, and the altered subvolcanic dacitic domes.     

A rigorous solution for the stability of polyhedral rock blocks

Block theory has been widely applied to stability analysis of rock engineering due to its clear concept and elegant geometrical theory. For a general block with multiple discontinuity planes, it is assumed that contact is only maintained on a single plane (single-plane sliding) or two intersecting planes (double-plane sliding) in block theory analysis. Since the normal forces and shear resistances acting on the other discontinuity planes are omitted, it can cause unreasonable estimations of block failure modes and incorrect calculation of factors of safety. In this study, a new method is presented that permits to consider the contribution of the normal forces and shear resistances acting on each discontinuity plane to the block stability. The proposed method meets all of the force-equilibrium and moment-equilibrium conditions and provides a rigorous solution for stability of general blocks with any number of faces and any shape. Some typical polyhedral blocks in rock slopes are analyzed using block theory and the proposed method. The results indicate that the traditional block theory may give a misleading conclusion for the predictions of stability and sliding direction of rock blocks when contact occurs on more than two discontinuity planes.     

辽宁中部城市群夏季大气能见度的观测研究

利用2009年6—8月辽宁中部4个城市的观测资料,分析了辽宁中部城市群夏季的季、月、日能见度分布,并探讨了能见度的日变化特征及其影响因子。结果表明:辽宁中部城市群内各城市夏季大气能见度月际变化趋势基本一致,天气系统和大气环境比较均一,具有明显的区域性特征;各城市大气能见度日变化呈明显的单周期谷、峰形分布,06时前后能见度最差,15—16时最好;大气细粒子、水汽和风速都对城市群能见度有一定的影响,其中,大气细粒子是主要影响因子;城市群夏季的低能见度时次,仅有一小部分是由轻雾引发的,而大部分则是由霾天气造成的。