遵义市近10 a来降温频次及强度分析

选取遵义市13个国家站2010—2019年逐日日最低气温资料,将降温过程分为弱降温、较强降温、强降温、寒潮4个等级,分析了各级降温过程的频次、持续日数、降温幅度、过程最低气温、空间分布等特征。分析表明：① 10 a来遵义市共发生降温过程11 915站次,平均每站每年91.7次,以降温幅度在6 ℃以下的弱降温为主。②近10 a遵义市平均过程降温幅度为3 ℃,平均过程最低日低温11.9 ℃,持续时间在1~10 d之间,寒潮、强降温、较强降温持续天数以2~3 d为主,弱降温过程大多持续1 d。③不同等级降温频次空间分布与地形相关,较强降温以上的降温过程主要集中出现在遵义市娄山以南地区,弱降温主要出现在娄山山区及其西北部。④寒潮、强降温、较强降温主要出现在春秋季,寒潮主要出现在3月份,而弱降温在夏季发生频次较高,4月份是遵义市降温最剧烈的时候。     

基于模糊神经网络的多变量系统的解耦方法

针对多变量、强耦合、纯迟延系统,提出一种模糊神经网络的解耦方法,结合遗传算法、将多变量系统解耦成单变量系统。传统解耦方法对于非线性系统、变结构系统以及耦合关系和耦合强度随时间和负载变化的复杂系统经常无能为力,而这种综合了模糊逻辑和神经网络优势的解耦方法,由于具有非线性和自学习能力,使其解耦性能不受影响,弥补了传统解耦方法的缺陷,对复杂系统有着较好的解耦能力。且该方法不需要建立精确的数学模型,易于实现。文章最后通过仿真实验验证了该模型的解耦效果。     

Geochemical constraints on mixed source and hydrocarbon filling process in the Yingjisu Sag,Tarim Basin,Xinjiang

The Yingjisu Sag was petroliferous for normal oil, condensate oil, reservoir bitumen and natural gases. Geochemical studies showed that natural gases in the Yingjisu Sag were a gas mixture consisting mainly of Cambrian pyrolysis gas, Jurassic condensate oil in well Yingnan 2 and normal oil in well Tadong 2, reflecting the characteristics of marine-phase gases and oils, while crude oils in well Longkou 1 demonstrated the characteristics of both marine and terrestrial oils, which were derived from lower algae and higher plants. Jurassic oils from wells Longkou 1 and Huayingcan 1 and Cambrian crude oils from well Tadong 2 were derived mainly from Cambrian-Lower Ordovician source rocks. Jurassic and Silurian reservoir bitumens from well Yingnan 2 were biodegradated, suggesting they are of marine and terrestrial origins. The bitumens have similar geochemical characteristics, which are correlated well with Ordovician crude oils from well Tadong 2 and Jurassic condensate oil from well Yingnan 2. Based on the characteristics of tectonic evolution in this area and the analysis of hydrocarbon accumulation, the constraints on the mixed source and hydrocarbon filling process in the Yingjisu Sag were brought forward.     

Driving forces behind land use and cover change in the Qinghai-Tibetan Plateau: a case study of the source region of the Yellow River,Qinghai Province,China

Research on land use and cover change (LUCC) is an important aspect of the study of global change or global warming. The Qinghai-Tibetan Plateau is a good place to study global change because of its unique natural conditions, so we chose the source region of China’s Yellow River for a case study of the driving forces behind LUCC. We used Landsat images obtained in 1989, 2000, and 2005 to establish databases of land use and cover at these times. We then derived LUCC information by overlaying these layers using GIS software. By studying the processes responsible for LUCC, we analyzed the driving forces, which included climatic change, human activities, animal and insect damage, and the influences of government policies. During the 16-year study period, LUCC occurred slowly in response to two groups of processes: natural and anthropogenic. The main driving forces included climate change (the region is becoming drier and warmer), human activities (especially overgrazing), and animal and insect damage. Although political measures such as key national projects to improve the ecological environment could help to restore the region’s vegetation and slow desertification, the region’s fragile ecosystems and harsh natural conditions will make it extremely difficult to rehabilitate the eco-environment.     

The effect of three-dimensional variational data assimilation of QuikSCAT data on the numerical simulation of typhoon track and intensity

In this paper, the three-dimensional variational data assimilation scheme (3DVAR) in the mesoscalemod el version 5 (MM5) of the US Pennsylvania State University/National Center for Atmospheric Research is used to study the effect of assimilating the sea-wind data from QuikSCAT on the prediction of typhoon track and intensity. The case of Typhoon Dujuan (2003) is first tested and the results show appreciable improvements. Twelve other cases in 2003 are then evaluated. The assimilation of the QuikSCAT data produces significant impacts on the structure of Dujuan in terms of the horizontal and vertical winds, sealevel pressure and temperature at the initial time. With the assimilation, the 24-h (48-h) track prediction of 11 (10) out of the 12 typhoons is improved. The 24-h (48-h) prediction of typhoon intensity is also improved in 10 (9) of the 12 cases. These experiments therefore demonstrate that assimilation of the QuikSCAT sea-wind data can increase the accuracy of typhoon track and intensity predictions through modification of the initial fields associated with the typhoon.     

塔里木盆地良里塔格地区奥陶系生物礁的沉积特征和成礁模式*

塔里木盆地奥陶系生物礁储集层受到广泛关注。笔者优选塔里木盆地良里塔格地区奥陶系鹰山组顶部生物礁体(NYG-1)和一间房组底部生物礁体(NYG-2)为研究对象,通过详细的野外观察、实测和薄片鉴定,对生物礁的生物类型、岩性特征和沉积相单元进行分析。结果表明:塔里木盆地良里塔格地区鹰山组和一间房组的造礁生物主要由瓶筐石组成,与生物礁相关的岩性有障积礁灰岩、粘结礁灰岩、生屑粒泥灰岩、生屑泥粒灰岩、内碎屑泥粒灰岩、生屑颗粒灰岩、内碎屑颗粒灰岩和球粒颗粒灰岩。NYG-1礁体发育礁基、礁核、礁顶、礁翼和礁盖5个沉积相单元;NYG-2发育礁基、礁核与礁盖3个沉积相单元。从生物类型来看,鹰山组的礁为托盘—障积礁,为近似圆形的台内点礁,展布无明显的方向性;一间房组的礁为托盘障积—粘结礁,属台缘礁,常呈现出礁体迁移的特征。鹰山组和一间房组成礁模式的共同点是都经历了礁基的形成、礁体的发育和礁体的衰亡3个阶段,而差异主要表现在生物礁体的灭亡阶段: 对鹰山组生物礁而言,海平面的快速下降和高能水动力条件导致了瓶筐石的灭亡和内碎屑灰岩的产生;对一间房组生物礁而言,海平面的上升和浮游藻类生物大量发育造成造礁生物甁筐石的灭亡。以上研究对于建立符合塔里木盆地地区条件的礁体沉积模式和探索露头与井下生物礁对比研究有重要意义。     

砾质辫状河型冲积扇沉积微相及沉积模式:以准噶尔盆地西北缘现代白杨河冲积扇为例*

冲积扇砂砾岩储集层具有相变快、连续性差等特点,显示冲积扇内部沉积环境的复杂性。本次研究以准噶尔盆地西北缘现代白杨河冲积扇为例,在丰富的野外露头资料基础上,结合区域水文资料以及冲积扇文献资料,对白杨河冲积扇沉积演化特征及沉积模式进行探讨。按其沉积机制,白杨河冲积扇属于辫状河型冲积扇,具有规模大(扇体总面积约327.6km²)、坡度平缓(约4‰~7‰)、沉积粒度粗和漫洪细粒沉积物不发育的典型特征。在白杨河冲积扇内共可识别出16种岩相类型,并根据岩相形成的流体动力差异划归为5类成因,即重力流成因、高流态牵引流成因、低流态牵引流成因、静水沉积成因以及风成沉积成因。白杨河冲积扇扇体建造过程可划分为洪水期和间洪期2个时期,洪水期以沉积作用为主,从扇根至扇缘依次发育扇根补给水道沉积、扇根片流沉积、扇中片流沉积、扇中辫状水道沉积、扇缘径流水道沉积和扇缘湿地沉积6种沉积微相类型;间洪期以改造作用为主,从扇根至扇缘依次发育扇根主槽沉积、扇中辫状沟槽沉积和扇缘湿地沉积3种沉积微相类型。最后,依据白杨河冲积扇建立了砾质辫状河型冲积扇洪水期和间洪期的沉积模式。     

基于Poynting矢量的地震照明分析

地震照明分析能够定量分析影响逆时偏移成像质量的因素。文章基于Poynting矢量方法进行地震定向照明分析及成像补偿方法研究,利用Poynting矢量进行波场传播角度分解,通过计算不同入射及散射波方向的部分照明建立局部照明矩阵。该矩阵包含了照明分析中波与地质结构相互作用所涉及的所有角度信息,可以方便地分析目标附近所有可能的入射波和散射波对局部照明的贡献。根据局部照明矩阵可以获得对地下结构的照明描述、采集倾角响应,并依此进行成像补偿计算。以SEG/EAGE模型作为数值计算实例,进行基于Poynting矢量的照明分析及成像补偿,有效地提高了成像质量。该方法为角度域逆时偏移成像校正及分辨率分析等提供了高效的处理手段。     

Coagulation performance and microstructural morphology of a novel magnetic composite coagulant for pre-treating landfill leachate

A novel magnetic composite coagulant, prepared from nano-Fe₃O₄ and poly-aluminum chloride, was introduced to pre-treat mature landfill leachate. The coagulation performance of the coagulant as well as its microstructural morphology was discussed. Coagulation experimental results revealed that the coagulation performance of the landfill leachate using the new coagulant was better than that using poly-aluminum chloride alone, with COD and color removals above 60 and 68%, respectively. Based on the analysis of three-dimensional excitation–emission matrix spectrum, the fluorescence signals of treated leachate are totally reduced by the magnetic composite coagulant. The components of dissolved organic matters in the wastewater are removed in different degrees. Fourier transform infrared spectra analysis shows that the magnetic composite coagulant, which is a multi-core polymer with hydroxyl ligands and nano-Fe₃O₄, has a complex valence and crystal structure. Besides, X-ray diffraction pattern analysis indicates that the chemical composition of the magnetic composite coagulant is not changed significantly, which has comprehensively combined the chemical characteristics of both nano-Fe₃O₄ and poly-aluminum chloride, whereas the specific surface area of the novel magnetic composite coagulant effectively increased by nano-Fe₃O₄ particles under the analysis of scanning electron microscope spectral. The specific surface area analysis indicates that the magnetic composite coagulant is interconnected by narrow cracks and holes and has a high specific surface area and developed pore structure, which is also similar to the typical porous-type materials. Therefore, the nano-Fe₃O₄ compounded with poly-aluminum chloride leads to a larger specific surface, smaller average pore diameter, and more pore volume of the novel coagulant.     

Combined spheropolyhedral discrete element (DE)–finite element (FE) computational modeling of vertical plate loading on cohesionless soil

This paper presents a combined spheropolyhedral discrete element (DE)–finite element (FE) computational approach to simulating vertical plate loading on cohesionless soils such as gravels. The gravel particles are modeled as discrete elements, and the plate is modeled as a deformable FE continuum. The simulations provide a meaningful step toward better understanding how deformable bodies transmit loads to granular materials. The DE–FE contact algorithm is verified through comparison with an analytical solution for impact between two symmetric bars. A parametric study is conducted to ensure boundary effects are not significantly influencing the simulations. Numerical simulations are compared to experimental test results of lightweight deflectometer loading on a gravel base course with satisfactory agreement. Future developments of the approach intend to simulate wheel loading of military aircraft on unsurfaced airfields.