Chi-square tests for markov chain analysis

Markov chain analysis has become a popular and useful technique for the evaluation of stratigraphic information. Field data on frequencies of facies transitions are first assembled in a transition count matrix. Observed frequencies can be compared statistically with frequencies expected if no order, or memory, exists in the stratigraphic sequence. Two chi-square (²) tests have been proposed for this purpose. One of the previously proposed ² tests was observed to give anomalously large values of the test statistic during another study. This unsatisfactory behavior is verified here. Limiting values of the two ² tests (from tables) are compared with the distribution of values for both test statistics obtained by analyzing many random matrices generated by a simple computer program. In all cases, the logarithmic ² test, suggested by several previous authors, fails to provide any meaningful assessment of the presence or absence of order in stratigraphic sequences evaluated. Further use of this test should therefore be avoided.     

螺旋板载荷试验资料整理若干问题探讨

螺旋板载荷试验对获取地下水位以下土层的工程参数具有无可比拟的优势 ,但在试验资料的整理分析方面 ,尚有若干问题需要解决。在大量试验的基础上 ,对这些问题进行了有益的探讨。     

用CASIOfx—4000p敷设高等级公路中线

本文主要介绍了敷设高等级公路平线时，在CASIOfx－4000p计算器上使用的程序及操作．     

自回归预测模型变权组合定阶

针对自回归(AR(p))预测模型定阶问题中回溯阶的不确定性和时变性,以及基于单一回溯阶预测方法的局限性和组合预测中的冗余信息等问题,该文提出了一种基于遗忘因子的变权组合定阶方法。利用冗余定理筛选基于多个回溯阶预测方法的有效信息,并利用遗忘因子实现了组合权重的时变性,克服了基于单一回溯阶预测模型稳健性欠缺、预测精度低等局限性,提高了预测能力。通过实例表明该算法具有高度的可靠性和可行性,为类似预测方法的定阶问题提供了研究思路。     

P(x)-Laplace方程正径向解的唯一性定理

本文给出了一类p(x)-Laplace方程的正径向解在单位球上的1个唯一性定理,文章中假定p(x)是径向的单调函数．并且非线性项满足某种单调性条件。     

Trend analysis and first time observations of sulphur dioxide and nitrogen dioxide in South Africa using TROPOMI/Sentinel-5 P data

The 17 Sustainable Development Goals (SDGs) aim to end extreme poverty and create a healthy, sustainable world by the year 2030. Goal 7 is of interest to this study as it targets access to clean and affordable energy. However, in this study we show that the energy created in South Africa is not necessary clean. South Africa has numerous coal-fired power station located in the Mpumalanga (MP), Gauteng (GP) and Limpopo (LP) provinces. These power station produce tons of toxic pollutants including sulphur dioxide (SO₂), nitrogen dioxide (NO₂) and sulphates (SO₄). These pollutants are known to have a negative impact on human health, climate and the environment. In this study we use the sequential Mann-Kendall test to investigate the 39 year (1980–2019) trends of SO₂, NO₂ and SO₄ from these source areas. We also report for the first time on the observations of SO₂ and NO₂ from the Sentinel-5 P sensor over South Africa. Increasing trends of SO₂ were observed in the MP, LP and GP regions. The increase was mostly due to the emissions from coal-fired power stations. Moreover, the increase of SO₂ over the years could be due to the increasing demand in electricity, aging power stations and the low quality of coal used. Sentinel-5 P observations of SO₂ and NO₂ over South Africa were observed in the MP, GP and LP regions as a result of coal-fired power stations. Dispersion of SO₂ and NO₂ over South Africa were observed in the winter months, while confined SO₂ and NO₂ in the source region were observed in the summer months.     

一个基于广义塑性力学的土体三屈服面模型

按照广义塑性力学原理 ,以前人试验结果为依据 ,首次提出应力洛德角方向上剪切屈服面 V θ p的数学表达式 ,并建立土体的三屈服面模型。 结合数值算例 ,设计多种计算方案 ,通过对计算结果的分析和比较 ,表明模型的合理性和有效性 ,并探讨各种因素对土体变形的影响。     

基于极大熵和小波的时间序列数据预测研究

在极大熵准则的基础上,以苏州虎丘塔的历史形变观测数据为例,进行时序数据的预测分析。研究不同的样本数据选择原则对预测效果的影响。然后在一致的样本基础上,得到基于不同的模型参数估计方法的时序数据预测曲线,并通过小波的去噪分析进行不同曲线之间优劣的比较。结果表明,在1985年到2000年期间,塔体的变形周期在不断的延长,但总体而言,塔体的变形是在不断的加剧。而基于极大熵参数估计法的AR(p)模型能对实际的观测曲线有很好模拟和预测效果,选择均匀步长的样本数据对提高模型预测精度是很重要的。     

养殖珍珠的分级与报价体系

针对我国制定的珍珠分级国家标准,仅对影响珍珠品质各因素做了等级划分,并未给出首饰级珍珠的总品质等级的确定方法和标准,造成分级标准与国际上报价体系不接轨,使其在市场上无法广泛应用等问题,系统总结国际流行的各大珍珠分级标准和报价体系,通过对比分析我国国标存在的问题,提出我国养殖珍珠分级和报价的改进方法。即借鉴美国GIA或RichardH．Cartier的珍珠总品质分级方法,在原国家分级标准上根据各品质因素对总品质影响权重计算珍珠总品质等级（1～10级）;并推行对应珍珠总质量等级的报价体系,呼吁国家权威机构定期发布珍珠价格信息,以规范珍珠市场,为珍珠评估提供依据。     

湖北大别山黄土岭麻粒岩中冠状体结构特征及其地质意义

湖北黄冈黄土岭麻粒岩的矿物组合为斜方辉石（Ⅰ）＋石榴子石＋斜长石（Ⅰ）＋石英。在石榴子石的边部出现堇青石＋斜方辉石（Ⅱ）组成的冠状体，它揭示曾发生如下变质反应：石榴子石±石英→英青石＋斜方辉石（Ⅱ）。温压估计结果表明，麻粒岩的形成温压分别为857～998℃和1．18～1．23GPa；而堇青石＋斜方辉石（Ⅱ）冠状体的形成温压分别为829～911℃和0．53～0．59GPa。上述结果显示麻粒岩形成后大别杂岩曾发生一次近绝热的快速隆升减压退变过程。该地麻粒岩的温压条件与Harley（1989）给出的世界90个麻粒岩产地的温压条件相比属于高压类型［1］，代表该岩石曾达40km以上的下地壳深度。