东营凹陷民丰地区天然气生成机理与化学动力学研究   总被引：3，自引：0，他引：3  

王秀红  金强  胡晓庆  陈涛  宋国奇  王力  王娟  林腊梅  陈志伟 《沉积学报》2008,26(3):525-530

民丰地区天然气存在源岩热解和原油裂解成因的争议。本文采用高压釜封闭体系对该区烃源岩和原油样品分别进行了热模拟实验,从烃类气体生成过程、气态烃与部分单体烃生成动力学特征讨论了二者的生气机理,认为原油裂解比源岩热解生气活化能高30～40 kJ/mol,原油比源岩生气需要更高的热力学条件。模拟实验证实,成熟阶段源岩热解气与原油裂解气相比,以环烷烃和芳烃相对含量低为特征,与民丰地区产出的天然气组成更接近,据此认为该区天然气主要为源岩热解成因。  相似文献   

The conservation patterns of grassland ecosystem in response to the forage-livestock balance in North China     

HUANG Lin  NING Jia  ZHU Ping  ZHENG Yuhan  ZHAI Jun 《地理学报(英文版)》2021,31(4):518-534

Being a key ecological security barrier and production base for grassland animal husbandry in China,the balance between grassland forage supply and livestock-carrying pressure in North China directly affects grassland degradation and restoration,thereby impacting grassland ecosystem services.This paper analyzes the spatiotemporal variation in grassland vegetation coverage,forage supply,and the balance between grassland forage supply and livestock-carrying pressure from 2000 to 2015 in North China.We then discuss the spatial pattern of grassland ecological conservation under the impacts of grassland degradation and restoration,and livestock-carrying pressure.Over the last 16 years,the total grassland area in North China decreased by about 16,000 km2,with vegetation coverage degraded by 6.7％ of the grasslands but significantly restored by another 5.4％ of grasslands.The provisioning of forage by natural grassland mainly increased over time,with an annual growth rate of approximately 0.3 kg/ha,but livestock-carrying pressure also increased continuously.The livestock-carrying pressure index without any supplementary feeding reached as high as 3.8.Apart from the potential livestock-carrying capacity in northeastern Inner Mongolia and the central Tibetan Plateau,most regions in North China are currently overloaded.Considering the actual supplementary feeding during the cold season,the livestock-carrying pressure index is about 3.1,with the livestock-carrying pressure mitigated in central and eastern Inner Mongolia.Assuming full supplementary feeding in the cold season,livestock-carrying pressure index will fall to 1.9,with the livestock-carrying pressure alleviated significantly in Inner Mongolia and on the Tibetan Plateau.Finally,we propose different conservation and development strategies to balance grassland ecological conservation and animal husbandry production in different regions of protected areas,pastoral areas,farming-pastoral ecotone,and farming areas,according to the grassland ecological protection patterns.  相似文献   

碳酸氢钠冷却结晶动力学          下载免费PDF全文

蒋士姣 《盐湖研究》2021,29(2):50-57

碳酸氢钠(NaHCO_3)俗称小苏打,其产品质量取决于颗粒的大小,晶体的形貌和样品的纯度等诸多因素。本论文基于连续稳态MSMPR结晶器原理,研究了不同停留时间下,碳酸氢钠从碳酸钠溶液中冷却结晶过程动力学。利用实验数据建立了NaHCO_3的结晶动力学操作模型。实验和计算结果表明,随停留时间的增加,NaHCO_3过饱和度降低,晶体生长速率和成核速率均减小,相应的平均粒径增加,细颗粒含量减小;适当延长停留时间是制取高品质小苏打产品的有效途径。冷却结晶过程可有效增加小苏打产量,小苏打收率维持在55%左右。此外,一定Na_2CO_3存在下冷却结晶碳酸氢钠晶体形态由细长的针状变为规整的片状。  相似文献   

Pumping decisions for sustainable development of groundwater resources in areas of grassland degradation: a case study in Lanqi Banner, Inner Mongolia, China     

Bagen Chaolun  Bin He  Ruizhong Gao  Liang Wang 《Hydrogeology Journal》2008,16(6):1101-1111

The best planting alternatives for satisfying high water use demands of forage and fodder crops in a region of Inner Mongolia, China, were determined by a multiobjective distributed-parameter groundwater management model. These alternatives took account of different cropping patterns and pumping decisions associated with both temporal and spatial aspects of water allocation. The model was developed for phreatic, homogenous, and isotropic aquifers using the response matrix technique of quadratic programming theory and, in this case, using the alternative direction implicit (ADI) scheme. Model solutions using effective rainfall with a probability of 50%, show that average water table drawdown in the planning period (2006–2017) is 0.22 m and the groundwater fluctuation in each pumping well is very low. In order to evaluate the pumping decisions under an effective rainfall with a probability of 75%, a sensitive analysis was also conducted. Analysis shows that it is useful to apply the results from the proposed model to control the landscape degradation due to overgrazing and overpumping activities.  相似文献   

Researches on the Internal Molecular Weight Uniformity of Chitosan Biomaterials     

LANG Xuqian  LI Yang  SUN Guohui  ZHOU Zhongzheng  LI Jing  FENG Chao  KONG Ming  LIU Ya  CHENG Xiaojie  CHEN Xiguang 《中国海洋大学学报(英文版)》2020,19(2):459-465

Uniform molecular weight(Mw)chitosan(CS)is highly demanded in medical biomaterial industry.This present article described heterogeneous degradation of CS in aqueous HCl/ethanol solution,in which progress uniform Mw CS was successfully prepared.The Mw distribution of CS was measured by gel permeation chromatography(GPC)analysis.Moreover,the structure and properties of degraded CS were characterized by Fourier transform infrared spectroscopy(FT-IR),nuclear magnetic resonance spectroscopy(^1H NMR),X-ray diffraction(XRD)and thermogravimetric(TG)analysis.In addition,the biocompatibility of degraded CS was also assessed by hemolysis rate(HR)measurement.The Mw of CS dramatically decreased from 246 KDa to 76 k Da at the initial 30 min,and stabilized at 18 kDa after 24 h.GPC analysis results showed that the degraded CS molecular become homogenization.FT-IR and 1 H NMR analysis confirmed the basic structure of CS molecular backbone was not destroyed during this progress.Besides,the water solubility of CS was not significantly influenced by this reaction.Moreover,the XRD analysis revealed that crystallinity of degraded CS increased from 70.32% to 99.25%with time.The TG analysis showed improved thermal stability of degraded CS.HR measurement demonstrated the degraded CS possessed excellent biocompatibility.This simple and efficient heterogeneous degradation would open up a new route to produce uniform Mw CS.  相似文献   

Reaction time scales for sulphate reduction in sediments of acidic pit lakes and its relation to in-lake acidity neutralisation     

《Applied Geochemistry》2016

Sulphate reduction is a key reaction to remove acidity from water bodies affected by acid mine drainage. In this study, ³⁵SSO₄²⁻ reduction rates determined in sediments from a variety of acidic lignite pit lakes have been compiled. The rates decreased with pH and are strongly dependent on carbon substrate. The rates were fitted to a Monod model adapted to the specific conditions of acidic pit lakes (APL) sediments: i) sulphate reduction rate is independent from sulphate concentration due to the high concentration typically observed in APL systems (10–30 mM), ii) the observed pH dependency of sulphate reduction was accounted for by an inhibition function F_inihibt which considers the occurrence of low cell numbers of sulphate reducing bacteria at pH values < 4.75. Simulated steady-state sulphate reduction rates are predicting measured rates at carbon substrate concentrations of <10 μM. Estimated steady-state reaction time scales range between 2.4 h at pH 7 and 41 h at pH 3 at a carbon half-saturation constant of K_C−S = 100 μM and are increasing with increasing K_C−S values. Time scales at low pH are too long to allow for significant generation of alkalinity during the time of residence of groundwater passing through the top and hence most reactive zone of APL sediments which has important implications for the remediation of acidic pit lakes.  相似文献   

Validation of MODIS Vegetation Continuous Fields for monitoring deforestation and forest degradation: two cases in Mexico     

Yan Gao  Adrian Ghilardi  Jaime Paneque-Galvez  Margaret Skutsch  Jean François Mas 《国际地球制图》2016,31(9):1019-1031

This study assesses whether MODIS Vegetation Continuous Fields percent tree cover (PTC) data can detect deforestation and forest degradation. To assess the usefulness of PTC for detecting deforestation, we used a data set consisting of eight forest and seven non-forest categories. To evaluate forest degradation, we used data from two temperate forest types in three conservation states: primary (dense), secondary (moderately degraded) and open (heavily degraded) forest. Our results show that PTC can differentiate temperate forest from non-forest categories (p = 0.05) and thus suggests PTC can adequately detect deforestation in temperate forests. In contrast, single-date PTC data does not appear to be adequate to detect forest degradation in temperate forests. As for tropical forest, PTC can partially discriminate between forest and non-forest categories.  相似文献   

从平衡-封闭-静态转向非平衡-开放-动力学研究-热液矿床成因的若干新概念概述     

张荣华  胡书敏  张雪彤 《地质学报》2016,90(9):2437-2453

热液金属矿床成因研究过程中,观测与实验始终是密切结合的。上世纪70年代,平衡热力学的实验数据的快速积累,使人们用热力学理论计算可以预测和反演矿石和岩石的成因。但是,没有矿物-水溶液的反应速率数据,又没有与流体力学的结合,搞清楚矿石成因是困难的。七、八十年代,开始研究矿物与水溶液的反应动力学实验。科学家们开始瞄准了从平衡-封闭-静态转向非平衡-开放-动力学研究的这个大方向。1992年我们建立地球化学动力学开放研究实验室。研究高温高压矿物与水反应速率,发现固液的开放体系的自组织现象。实验发现温度影响矿物的各个元素反应速率改变,发现在跨越水临界态时矿物与水反应速率涨落、在近临界的气-液两相不混溶区一些金属进入气相、超临界流体的氧化作用及特别的溶剂性能影响矿物溶解性质。实验证实:临界态区流体与矿石成因有关。水岩相互作用的反应动力学实验温度从低温到550度,揭示矿石的金属来源、迁移、金属与蚀变分带机制。一大批大于300度的矿物与水反应动力学实验在国际界是少有报道的。九十年代,超高压的科学发展,与同步辐射光源的技术进步的结合,使固体地球科学又迈向了地球深内部。我们发展了高温高压流体性质的原位直测(测量850℃水溶液)红外谱,发现深部流体的新性质:气液两相流体的新结构,在临界温度区(300~400℃),水分子氢键网络的破坏受压力影响不大(23MPa~3GPa),同时,出现水的高电导率。研发新仪器为开放-流动-非平衡的反应动力学实验与极端条件下物质性质的直接观测结合,在科学前沿领域开辟了创新道路。  相似文献   

执行器退化的遥机器人系统量化反馈容错控制     

郑柏超  傅曦雨  杨鑫  阚亚进 《南京气象学院学报》2016,8(6):499-504

针对遥机器人系统中存在执行器退化、控制输入量化,且编、解码端的量化灵敏度参数不匹配的问题,设计了遥机器人系统的鲁棒量化反馈容错控制系统.控制器结构的线性部分由线性矩阵不等式给出,旨在解决系统指标性能问题,非线性部分则用于处理量化参数不匹配问题.经稳定性理论证明,提出的鲁棒量化反馈容错控制方法能消除执行器退化及量化参数不匹配等的影响,并确保从机器人能渐近跟踪主机器人.最后,算例仿真验证了方法的有效性.  相似文献   

Modelling of deformation response and chemo‐mechanical coupling in chalk     

S. Pietruszczak  D. Lydzba  J. F. Shao 《国际地质力学数值与分析法杂志》2006,30(10):997-1018

A constitutive relation is derived for describing the mechanical response of chalk. The approach is based on a phenomenological framework which employs chemo‐plasticity. The properties of the material are assumed to be affected by the physico‐chemical processes that occur through the interaction between the skeleton and the pore fluid. The underlying mechanism is discussed by invoking a micromechanical analysis. The performance of the framework is illustrated by examining the evolution of mechanical characteristics in the presence of different pore fluids. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献