马尔柯夫链在江汉平原第四纪沉积环境分析中的应用

应用马尔柯夫链基本原理,在系统统计江汉平原监利县周老镇ZL01钻孔揭示的第四系基础上,结合该区的地质特征,进行了极限概率分析、差值矩阵分析、置换分析和熵分析.根据马尔柯夫链的综合分析结果,总结出江汉平原周老镇ZL01钻孔剖面的第四纪沉积主旋回,发现该剖面主要形成于河流沉积环境,并建立了该区第四系的地方性沉积相模式,为研究该地区的沉积作用、判断沉积环境提供定量的解释依据,对研究江汉平原的变迁历史及其保护和开发利用具有重要意义.     

山东省铁矿资源供需形势分析

钢铁工业对促进经济和社会发展起着重要作用,随着社会经济迅猛发展,山东省钢铁工业取得快速发展,目前,山东省铁矿石消费量仍处于上升趋势,在此基础上,通过回归分析法预测未来5~10年山东省地区生产总值,运用综合平均增长率法、单位GDP矿石量法、回归分析法来预测未来铁矿石的需求量。预计2025年,山东省铁矿石产量为3561.44万t,消费量为11720.45万t,供需缺口为8159.01万t,由此预测69.6%的铁矿石依靠外省调入或进口;2030年铁矿石产量为4688.34万t,消费量为13219.06万t,供需缺口8530.72万t,预测64.65%的铁矿石依靠外省调入或进口。提出了山东省铁矿资源安全供应的对策建议:加强山东省富铁矿深部资源勘查,优化产业结构;深化矿业国际合作,结合国际合作和对外援助,互惠共赢。     

时空地统计学方法研究及进展

随着理论技术的不断发展,对环境因子仅进行空间估计和量化已不再满足精准农业等地理分支学科的精度要求,因此人们在传统地统计方法的基础上衍生出时空地统计学。该方法将时间域和空间域紧密联系起来,运用时空插值和随机模拟,更客观全面地描述地物的区域性时空分布。本文首先阐明了时空地统计学的主要概念及历史应用领域,随后介绍了当前主流的时空地统计方法及其各自的精度与适用领域,最后总结了时空地统计方法研究的不足和方向。     

新疆阿勒泰地区山绵羊死亡率灰色马尔柯夫预测

灰色ＧＭ（１，１）预测与马尔柯夫预测的优点可以相互补充，将两者结合起来对随机性和波动性较大的数据序列进行预测，精度更高。本文采用灰色与马尔柯夫两种预测的组合模型，对新疆阿勒泰地区山绵羊死亡率的时间序列进行了分析，并预测了１９９２的可能死亡率情况，为该地区畜牧业生产发展和防灾减灾提供了科学依据。     

Micro‐inertia origin of instabilities in granular materials

Within the framework of the second‐order work theory, the onset of instabilities is explored numerically in loose granular materials through three‐dimensional DEM simulations. Stress controlled directional analysis are performed in Rendulic's plane, and a particular attention is paid to transient evolutions at the microscale. Thanks to a micromechanical analysis, the onset and development of transient mechanical instabilities is explored. It is shown that these instabilities result from the unjamming and bending of a few force chains associated with a local burst of kinetic energy. This burst of kinetic energy propagates to the whole sample and provokes a generalized unjamming of force chains. As force chains buckle, a phase transition from a quasi‐static to an inertial regime is observed. At the macroscopic scale, this results in a transient softening and a loss of controllability. After the collapse of existing force chains, the development of plastic strain is eventually stopped as new stable force chains are built.     

Starved versus alluvial river bedforms: an experimental investigation

Laboratory experiments were conducted to investigate the formation of river bedforms under sediment supply-limited conditions, i.e. when a motionless substratum is bared by the dynamics of the mobile sediments. Three series of experiments were organized in a laboratory flume by fixing all the hydrodynamic and morphodynamic parameters but varying the thickness of the initial layer of mobile sediments which covers the rigid bottom of the flume. At the end of all the experiments, which lasted for the same amount of time, the formation of transverse sand dunes was observed. For decreasing , the rigid bottom of the flume was bared progressively earlier during the experiment and the measurements showed a clear tendency of the bedforms to lengthen, i.e. to increase their crest-to-crest distance. Moreover, under strong supply limitation, the two-dimensional transverse dunes turned into three-dimensional barchanoid forms and into isolated barchan dunes characterized by an abrupt reduction in bedform heights. A two-dimensional Fourier analysis of the bottom profile was performed, providing the amplitude of the main streamwise and spanwise harmonic components of the bottom morphology as a function of . © 2019 John Wiley & Sons, Ltd.     

A coupled CFD-DEM investigation of suffusion of gap graded soil: Coupling effect of confining pressure and fines content

Suffusion involves fine particles migration within the matrix of coarse fraction under seepage flow, which usually occurs in the gap-graded material of dams and levees. Key factors controlling the soil erodibility include confining pressure (p′) and fines content (F_c), of which the coupling effect on suffusion still remains contradictory, as concluded from different studies considering narrow scope of these factors. For this reason, a systematical numerical simulation that considers a relative wide range of p′ and F_c was performed with the coupled discrete element method and computational fluid dynamics approach. Two distinct macroresponses of soil suffusion to p′ were revealed, ie, for a given hydraulic gradient i = 2, an increase in p′ intensifies the suffusion of soil with fines overfilling the voids (eg, F_c = 35%), but have negligible effects on the suffusion of gap-graded soil containing fines underfilling the voids (eg, F_c = 20%). The micromechanical analyses, including force chain buckling and strain energy release, reveal that when the fines overfilled the voids between coarse particles (eg, F_c = 35%) and participated heavily in load-bearing, the erosion of fines under high i could cause the collapse of the original force transmission structure. The release of higher strain energy within samples under higher p′ accelerated particle movement and intensified suffusion. Conversely, in the case where the fines underfilled the voids between coarse particles (eg, F_c = 20%), the selective erosion of fines had little influence on the force network. High p′ in this case prevented suffusion.     

阿坝州壤塘县大骨节病区安全供水模式研究

通过调查研究阿坝州壤塘县已有供水措施及近期实施的地下水小型集中供水模式,从水质、水量、用水便捷程度等方面进行对比分析,探讨适合高寒高原区的安全供水模式,为改善病区生活饮用水条件提供借鉴。     

Significance of enhanced infiltration due to groundwater extraction on the disappearance of a headwater lagoon system: Toluca Basin, Mexico

Mexico City relies significantly on groundwater resources drawn from the Sistema Lerma well field located in the Toluca Basin, Mexico. Enhanced infiltration caused by groundwater extraction is suspected to be both a prime factor in the disappearance of a lagoon system at the Toluca Basin and a potential risk to long-term groundwater quality. A combined approach of field investigation and numerical modeling was adopted to assess the groundwater-surface water interactions within the lagoon system. Potentiometric data indicate that current downward vertical hydraulic gradients below the lagoon and surrounding wetland area are extremely low suggesting very slow infiltration rates. Geochemical and isotope data from surface water and groundwater sampling also indicate that very little surface water infiltration has occurred. Numerical simulations demonstrate that enhanced surface water infiltration is unlikely to be the primary cause in the significant reduction in size of the lagoon system. Other factors such as modifications to the surface water drainage system and capture of spring flow from the surrounding mountainous regions are likely more significant. Simulations also suggest that contaminants originating in the lagoon system are currently entering nearby production wells although the total contaminant mass flux to the wells is still very low and significantly diluted.

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Resumen La Ciudad de México depende significativamente de los recursos de aguas subterráneas obtenidos del campo de pozos Sistema Lerma ubicado en la Cuenca Toluca, oeste de la Cuenca de México. Se sospecha que la infiltración estimulada causada por extracción intensiva de aguas subterráneas es un factor principal en la desaparición de un sistema de lagunas en la cabeceras del Río Lerma en el centro de México y un riesgo potencial para la calidad de aguas subterráneas a largo plazo en la región. Se adoptó un enfoque combinado de investigación de campo y modelizado numérico para evaluar las interacciones de agua superficial-agua subterránea dentro del sistema de lagunas. Datos potenciométricos indican que los gradientes hidráulicos verticales descendentes actuales, ubicados por debajo de la laguna y vecina área de humedales, son extremadamente bajos sugiriendo ritmos de infiltración muy lentos. Datos geoquímicos e isotópicos provenientes del muestreo de agua superficial y subterránea también indican que ha ocurrido muy poca infiltración de agua superficial. Las simulaciones numéricas demuestran cuantitativamente que no es probable que la infiltración estimulada de agua superficial sea la causa principal en la reducción significativa del tamaño del sistema de lagunas en la cabecera. Otros factores tal como modificaciones al sistema superficial de drenaje de agua y captura de flujo de manantial en las regiones montañosas vecinas son probablemente más significativos. Las simulaciones también sugieren que los contaminantes que se originan en el sistema de lagunas están actualmente ingresando a pozos de producción cercanos aunque el flujo de masa contaminante total a los pozos es aún muy bajo y diluido significativamente en los volúmenes grandes de extracción. La magnitud de la amenaza a largo plazo a la calidad del agua subterránea en los pozos de producción Sistema Lerma proveniente de contaminantes infiltrados es una preocupación y amerita estudios futuros.

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Résumé La Cité de Mexico dépend significativement des ressources en eau souterraine pompées au site de captages de Sistema Lerma, dans le Bassin de Toluca, à lOuest du Bassin de Mexico. Laugmentation de linfiltration, causée par lextraction extensive des eaux souterraines, est suspectée dêtre à la fois un facteur primaire de la disparition dun système de lagons en amont de la rivière Lerma au centre de Mexico, et un risque potentiel à long-terme pour la qualité de leau souterraine dans la région. Uen approche combinée détudes de terrain et de modélisation numérique a été adoptée pour estimer les interactions entre les eaux de surface et les eaux souterraines, au sein du système de lagons. Les données potentiométriques indiquent que les gradients hydrauliques verticaux descendants sont très bas au niveau des lagons, ce qui suppose un taux dinfiltration faible. Les données géochimiques et isotopiques provenant des eaux de surface et souterraines, indiquent également que peu deau de surface sinfiltrent. La simulation numérique démontre quantitativement que laugmentation de linfiltration des eaux de surface nest probablement pas la première cause de réduction des lagons. Dautres facteurs, tels que les modifications du drainage des eaux de surface, laménagement en captage des sources situées aux pieds des montagnes environnantes, sont probablement plus importants. Les simulations suggèrent également que les contaminants provenant des lagons se retrouvent également dans les captages les plus proches, bien que le flux total de contaminants entrant dans les captages reste faible. Les volumes dextraction étant très important ils diluent effectivement les contaminants. Les effets à long-terme de lextraction critique au niveau des forages de Sistema Lerma et de la dégradation de la qualité des eaux souterraines par les contaminants, nécessite une grande attention pour le futur.

     

基于数字电位器的多通道程控高压调节系统设计

介绍了一种以数字电位器（MCP42010）和单片机（AT89S52）为核心的多通道程控高压调节系统的原理和结构。该系统电路简单%控制方便%成本低廉,它由多个被同一单片机控制的双通道数字电位器以及普通高压电源模块组成,能够实现两大功能,多通道选择和高压程控。通道的选择和具体电压大小的实现都通过一个带串口调试的图形化编程语言（VB）界面设置数据来控制,其应用程序采用面向硬件C语言程序（KEIL C）和VB编写。