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求解Covering问题的拟物方法——NP难度问题的一个处理途径 被引量:16
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作者 黄文奇 《计算机学报》 EI CSCD 北大核心 1989年第8期610-616,共7页
本文提出的算法模拟了由万有引力和屏蔽现象所引起的力学过程.这种拟物的方案可为许多NP难度的问题得出有价值的近似算法.该算法对拟物类型的选择与现代递归论中的有穷损害优先方法的精神是一致的.
关键词 covering问题 NP难度 拟物方法
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Gravity-based heuristic for set covering problems and its application in fault diagnosis 被引量:2
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作者 Yun Li Zhiming Cai 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2012年第3期391-398,共8页
A novel algorithm named randomized binary gravita- tional search (RBGS) algorithm is proposed for the set covering problem (SCP). It differs from previous SCP approaches because it does not work directly on the SC... A novel algorithm named randomized binary gravita- tional search (RBGS) algorithm is proposed for the set covering problem (SCP). It differs from previous SCP approaches because it does not work directly on the SCP matrix. In the proposed algo- rithm, the solution of SCP is viewed as multi-dimension position of objects in the binary search space. All objects in the space attract each other by the gravity force, and this force causes a global movement of all objects towards the objects with heavier masses which correspond to good solutions. Computation results show that the proposed algorithm is very competitive. In addition, the proposed aigodthm is extended for SCP to solve the fault diagno- sis problem in graph-based systems. 展开更多
关键词 set covering problem (SCP) gravity force binary search space fault diagnosis.
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Myotomy with Omentum Covering and Cardio-valvoplasty for Treatment of Achalasia
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作者 吴蕴真 尹兴家 +1 位作者 石文君 刘景华 《中国医科大学学报》 CAS CSCD 1990年第S1期72-75,共4页
Thirty one cases of the achalasia underwent myotomywith omentum covering and cardio-valvoplasty from 1983to 1988 at our hospital. Follow-up study, one to 4 yearspostoperatively, showed that 29 cases (93.5%) of themwit... Thirty one cases of the achalasia underwent myotomywith omentum covering and cardio-valvoplasty from 1983to 1988 at our hospital. Follow-up study, one to 4 yearspostoperatively, showed that 29 cases (93.5%) of themwith excellent results, only 2 cases(6.5%)showed slightdysphagia. The advantages of this procedure are as fol-lows: 1. relief of obstruction at lower end of esophagusand cardia preventing the recurrence of stenosis; 2. pre-vention of occurence of reflux esophagitis; 3. no altera-tion of normal anatomy of the esophagocardia region andno intervention of mucosa; 4. simplicity and safety ofthis procedure. 展开更多
关键词 ACHALASIA MYOTOMY OMENTUM covering cardio-valvoplasty
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Uncertainty and Reduction in Intuitionistic Fuzzy Covering Based Rough Sets
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作者 FENG Tao MI Ju-Sheng 《浙江海洋学院学报(自然科学版)》 CAS 2010年第5期481-487,共7页
This paper proposes a novel pair of induced IF covering approximation operators in an IF covering approximation space,and discusses some basic properties about definable IFSs.A measure is defined to describe the uncer... This paper proposes a novel pair of induced IF covering approximation operators in an IF covering approximation space,and discusses some basic properties about definable IFSs.A measure is defined to describe the uncertainty of IFSs in IF covering approximation spaces.Finally,we study the properties of reductions of an IF covering respectively based on induced IF covering approximation operators and IF covering approximation operators. 展开更多
关键词 IF covering induced IF lower and upper approximation operators REDUCTION UNCERTAINTY
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Numerical Characterizations of Covering Rough Sets Based on Evidence Theory
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作者 CHEN Degang ZHANG Xiao 《浙江海洋学院学报(自然科学版)》 CAS 2010年第5期416-419,共4页
Covering rough sets are improvements of traditional rough sets by considering cover of universe instead of partition.In this paper,we develop several measures based on evidence theory to characterize covering rough se... Covering rough sets are improvements of traditional rough sets by considering cover of universe instead of partition.In this paper,we develop several measures based on evidence theory to characterize covering rough sets.First,we present belief and plausibility functions in covering information systems and study their properties.With these measures we characterize lower and upper approximation operators and attribute reductions in covering information systems and decision systems respectively.With these discussions we propose a basic framework of numerical characterizations of covering rough sets. 展开更多
关键词 covering rough sets Attribute reduction Belief and plausibility functions Evidence theory
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Earth Science in the Era of Foundation Models:How AlphaEarth is Reshaping Quantitative Geoscience
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作者 CHENG Qiuming YANG Yilin +1 位作者 ZHOU Yuanzhi ZHANG Yuanzhi 《地学前缘》 北大核心 2025年第6期396-410,共15页
Since the beginning of the 21st century,advances in big data and artificial intelligence have driven a paradigm shift in the geosciences,moving the field from qualitative descriptions toward quantitative analysis,from... Since the beginning of the 21st century,advances in big data and artificial intelligence have driven a paradigm shift in the geosciences,moving the field from qualitative descriptions toward quantitative analysis,from observing phenomena to uncovering underlying mechanisms,from regional-scale investigations to global perspectives,and from experience-based inference toward data-and model-enabled intelligent prediction.AlphaEarth Foundations(AEF)is a next-generation geospatial intelligence platform that addresses these changes by introducing a unified 64-dimensional shared embedding space,enabling-for the first time-standardized representation and seamless integration of 12 distinct types of Earth observation data,including optical,radar,and lidar.This framework significantly improves data assimilation efficiency and resolves the persistent problem of“data silos”in geoscience research.AEF is helping redefine research methodologies and fostering breakthroughs,particularly in quantitative Earth system science.This paper systematically examines how AEF’s innovative architecture-featuring multi-source data fusion,high-dimensional feature representation learning,and a scalable computational framework-facilitates intelligent,precise,and realtime data-driven geoscientific research.Using case studies from resource and environmental applications,we demonstrate AEF’s broad potential and identify emerging innovation needs.Our findings show that AEF not only enhances the efficiency of solving traditional geoscientific problems but also stimulates novel research directions and methodological approaches. 展开更多
关键词 large-scale models artificial intelligence mineral prospectivity mapping AlphaEarth knowledge graphs deep and covered mineral exploration
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新型覆盖材料的保温效果及对大棚冬春反季节栽培辣椒生长的影响 被引量:3
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作者 孙艳军 徐刚 +2 位作者 高文瑞 于利 李德翠 《江西农业学报》 CAS 2010年第11期18-20,共3页
以草帘为对照,研究了4种无纺布的保温效果及对辣椒生长和发育的影响。结果表明,500 g/m2的无纺布的保温效果最好,150(加膜)、200、250 g/m2的无纺布的保温效果也都优于草帘;覆盖500 g/m2的无纺布的辣椒生长速度最快、开花结果早、前期... 以草帘为对照,研究了4种无纺布的保温效果及对辣椒生长和发育的影响。结果表明,500 g/m2的无纺布的保温效果最好,150(加膜)、200、250 g/m2的无纺布的保温效果也都优于草帘;覆盖500 g/m2的无纺布的辣椒生长速度最快、开花结果早、前期产量也最高,覆盖150(加膜)、200、250 g/m2的无纺布的辣椒生长发育和前期产量也都优于草帘。综合考虑保温效果、生产成本及操作方便,可以用200、250 g/m2的无纺布替代草帘,进行大棚冬春反季节辣椒生产。 展开更多
关键词 覆盖材料 保温效果 大棚 冬春 反季节栽培 辣椒生长 Plastic covering Materials 无纺布 前期产量 草帘 生长速度 生长发育 生产成本 开花结果 综合 操作
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CCA三支决策模型的边界域样本处理 被引量:3
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作者 张燕平 邹慧锦 +1 位作者 邢航 赵姝 《计算机科学与探索》 CSCD 2014年第5期593-600,共8页
构造性覆盖算法(constructive covering algorithm,CCA)三支决策模型在学习过程中根据样本分布特征,自动产生正域、负域和边界域。该模型为边界域样本处理问题提供了新的思路。重点讨论了基于CCA的三支决策的边界域样本处理问题。对边... 构造性覆盖算法(constructive covering algorithm,CCA)三支决策模型在学习过程中根据样本分布特征,自动产生正域、负域和边界域。该模型为边界域样本处理问题提供了新的思路。重点讨论了基于CCA的三支决策的边界域样本处理问题。对边界域样本处理提出了两种决策方案:一种为处理全部的边界域样本,给出了距中心最近原则、距边界最近原则、万有引力原则3种方法;另一种为处理部分的边界域样本,即只对满足一定条件的边界域样本作进一步的划分,这样使不满足条件的边界域样本仍保留在边界域,提高了边界域样本处理的正确率。用十字交叉法在5组数据集上对这两种决策方案进行了对比,实验结果表明,处理部分边界域样本时正确率更高,效果更好。 展开更多
关键词 构造性覆盖算法(CCA) 边界域样本处理 三支决策 CONSTRUCTIVE covering ALGORITHM (CCA)
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What kind of cotton ideotype is adapted to agroecological cropping systems and climate change in Benin?
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作者 ABOUA Dègbédji Charlemagne GÉRARDEAUX Edward +2 位作者 DEBAEKE Philippe BOULAKIA Stéphane SEKLOKA Emmanuel 《Journal of Cotton Research》 2025年第3期319-332,共14页
Background Agroecological cropping systems are recognised as an alternative way to ensure the sustainability of cotton(Gossypium hirsutum L.) production in the context of climate change and degradation of soil fertili... Background Agroecological cropping systems are recognised as an alternative way to ensure the sustainability of cotton(Gossypium hirsutum L.) production in the context of climate change and degradation of soil fertility. A study was conducted in Benin from 2020 to 2023 to compare six different cotton cultivars in three agroecological cropping systems in two cotton-growing zones. Plough-based tillage plus incorporation of cover crop biomass(PTI), conservation agriculture with strip tillage(CA_ST), and conservation agriculture with no tillage(CA_NT) were compared with the reference plough-based tillage(PT). The objective was to identify morpho-physiological traits of cotton that increase yield in agroecological cropping systems. Our approach combined a field experiment and crop simulation model(CSM) of CROPGRO-Cotton to evaluate the effects of genotype(G) × environment(E) × management(M) interactions on seed cotton yield(SCY).Results Cultivars Tamcot_camde and Okp768 and simulated ideotypes performed best in CA systems. Increased seed mass, large and thick leaves, and later maturity were identified as beneficial for yield enhancement in CA systems. Cultivars and ideotypes that combine these traits also resulted in better nitrogen and water use efficiencies in CA systems. Under different climate scenarios up to 2050, ideotypes designed could increase SCY in Benin.Conclusion A set of morpho-physiological traits associated with vegetative vigour is required to ensure a good SCY in agroecological cropping systems. These results provide scientific evidence and useful knowledge for breeders and research programmes on cropping systems focused on the adaptation of cotton to climate change. 展开更多
关键词 TILLAGE Agroecological practices Water status Gossypium hirsutum IDEOTYPE Seed cotton yield Cover crop CSM-CROPGRO-Cotton
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一种全覆盖的列控车载系统测试用例自动生成算法研究 被引量:25
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作者 袁磊 吕继东 +2 位作者 刘雨 李辰岭 赵伟慧 《铁道学报》 EI CAS CSCD 北大核心 2014年第8期55-62,共8页
列控车载系统是保证列车行车安全的重要装备,是典型的安全苛求系统。测试用例生成是测试车载系统功能的关键和基础。根据车载系统的特点,本文利用时间自动机建模工具UPPAAL,对车载系统模式转换的规范建立DRB-TE自动机网络模型,并指出车... 列控车载系统是保证列车行车安全的重要装备,是典型的安全苛求系统。测试用例生成是测试车载系统功能的关键和基础。根据车载系统的特点,本文利用时间自动机建模工具UPPAAL,对车载系统模式转换的规范建立DRB-TE自动机网络模型,并指出车载系统模型的非确定性会导致模式转换测试用例不能达到全覆盖。针对该问题设计一种能够满足全状态、全变迁覆盖准则测试用例的生成算法,利用实时系统测试用例自动生成工具CoVer生成模式转换测试用例套,从而实现自动生成覆盖全部车载模式转换规范的测试用例,同时提高了测试用例的生成效率和重用性。 展开更多
关键词 列控系统 基于模型的测试 测试准则 测试用例生成 UPPAAL COVER
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多端口形式化测试自动生成方法在CTCS-3车载系统中的应用 被引量:10
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作者 赵显琼 唐涛 《铁道学报》 EI CAS CSCD 北大核心 2011年第7期44-51,共8页
针对CTCS-3列控系统测试中普遍存在的需要多个端口协同测试的问题,在时间输入输出自动机(TIOA)的基础上,提出端口标记的时间输入输出自动机(LpTIOA)。LpTIOA除在模型中能够反映系统的时间约束特性外,还能反映系统输入输出行为对应的端... 针对CTCS-3列控系统测试中普遍存在的需要多个端口协同测试的问题,在时间输入输出自动机(TIOA)的基础上,提出端口标记的时间输入输出自动机(LpTIOA)。LpTIOA除在模型中能够反映系统的时间约束特性外,还能反映系统输入输出行为对应的端口信息,利用这些信息对基于覆盖度的搜索算法进行相应改进,形成包含端口信息的测试自动生成算法,用于生成满足给定覆盖度标准的测试套。文中还描述了运用UP-PAAL工具对LpTIOA模型实现建模的方法,并运用COVER工具实现对经过UPPAAL验证的CTCS-3级车载系统LpTIOA模型的测试套自动生成。 展开更多
关键词 CTCS 时间自动机 车载系统 UPPAAL 实时系统 COVER
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Characteristics of physical blocking on co-occupant's exposure to respiratory droplet residuals 被引量:3
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作者 李晓萍 牛建磊 高乃平 《Journal of Central South University》 SCIE EI CAS 2012年第3期645-650,共6页
Existed evidences show that airborne transmission of human respiratory droplets may be related with the spread of some infectious disease, such as severe acute respiratory syndrome (SARS) and H1N1 pandemic. Non-phar... Existed evidences show that airborne transmission of human respiratory droplets may be related with the spread of some infectious disease, such as severe acute respiratory syndrome (SARS) and H1N1 pandemic. Non-pharmaceutical approaches, including ventilation system and personal protection, are believed to have certain positive effects on the reduction of co-occupant's inhalation. This work then aims to numerically study the performances of mouth covering on co-occupant's exposure under mixing ventilation (MV), under-floor air distribution (UFAD) and displacement ventilation (DV) system, using drift-flux model. Desk partition, as one generally employed arrangement in plan office, is also investigated under MV. The dispersion of 1, 5 and 10 grn droplet residuals are numerically calculated and CO2 is used to represent tracer gas. The results show that using mouth covering by the infected person can reduce the co-occupant's inhalation greatly by interrupting direct spread of the expelled droplets, and best performance can be achieved under DV since the coughed air is mainly confined in the microenvironment of the infected person. The researches under MV show that the two interventions, mouth covering and desk partition, achieve almost the sarae inhalation for fine droplets while the inhalation of the co-occupant is lower when using mouth covering for large droplets. 展开更多
关键词 mouth covering desk partition respiratory droplets exposure ventilation method
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Flange Cover装置在海洋油气储运设施上的应用分析 被引量:1
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作者 刘焰明 刘吉飞 +2 位作者 程久欢 朱汉华 范世东 《船海工程》 北大核心 2017年第5期111-114,共4页
针对Flange Cover的安装空间及形式需求;在设计中采用经验公式对Flange Cover的尺寸及结构强度进行计算,采用ANSYS及CFD等数值分析辅助工具进行模拟及核算,得出满足安装、强度及J-60防火要求的Flange Cover形式。
关键词 立管 FLANGE COVER J60 ANSYS FLUENT
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基于T.Cover模型的时间分层决策矩阵算法 被引量:2
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作者 郑晓薇 龚兆仁 《计算机工程》 CAS CSCD 北大核心 2002年第2期142-143,151,共3页
讨论了一种基于最优投资决策模型的按时间分层决策矩阵的综合评价算法,该算法利用最优投资决策模型取得最优T.CoverT.Cover投资决策,并采用关系数据库语言加以实现。b*
关键词 最优投资决策模型 关系数据库 T·Cover模型 时间分层决策矩阵算法
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Non standard pallet series designing problem in ammunition supply system 被引量:2
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作者 LiLiangchun GuoMin WangHongwei 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2005年第1期74-77,共4页
According to the compound packing problem in ammunition supply system in our army, the non-standard pallet series design model is proposed, and the original problem that can be solved as a set cover problem with a nes... According to the compound packing problem in ammunition supply system in our army, the non-standard pallet series design model is proposed, and the original problem that can be solved as a set cover problem with a nested bin-packing problem, is analyzed, then two heuristic algorithms are applied to solve the problem. 展开更多
关键词 ammunition supply PALLET minimum set covering bin-packing.
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《农药手册》(The Pesticide Manual)推出在线网络版(Online Pesticide Manual) 被引量:1
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作者 杨新玲 《农药学学报》 CAS CSCD 北大核心 2015年第3期333-333,共1页
《农药手册》网络版涵盖了第16版印刷本的所有内容,而且实时更新,内容更加丰富,涉及10400余个产品名称,3100个停用产品名称和710个增补词条,与印刷版相比,检索更加便捷高效。
关键词 MANUAL 在线网络 印刷本 IUPAC 印刷版 NAMES biochemistry covering PATENT EXPORT
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改进的基于代码污染识别安全警告的算法
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作者 牛霜霞 吕卓 +1 位作者 张威 莫坚松 《计算机应用与软件》 CSCD 2016年第8期36-38,80,共4页
由于静态代码审计工具具有自动化、不容易出错的特点,开发人员经常使用它来检测代码漏洞,但是检测出的代码漏洞的结果会产生大量的警告信息,开发人员必须手动进行检查和纠正。此工具的缺点是浪费开发人员大量的时间。通过对用户的输入... 由于静态代码审计工具具有自动化、不容易出错的特点,开发人员经常使用它来检测代码漏洞,但是检测出的代码漏洞的结果会产生大量的警告信息,开发人员必须手动进行检查和纠正。此工具的缺点是浪费开发人员大量的时间。通过对用户的输入以及敏感数据流的追踪来确定警告的缺陷是否真的被利用,从而减少静态检测工具产生的大量警告数量。同时提供给开发者更多真正能对软件产生威胁的警告信息。针对静态代码审计工具的缺点,研究三种不同的方法来提高静态代码审计工具的性能。第一,对于商业性的静态代码分析工具Coverity,重新分析它的结果,并且从安全的角度创建一组具体的相关警告。第二,对开放的源代码分析工具Findbugs进行修改,并只对被用户输入所污染的代码进行分析。第三,研发灰盒代码审计工具,此工具侧重于Java代码中的跨站脚本攻击XSS(Cross Site Scripting),使用数据流分析的方法来确定漏洞的切入点。实验结果证明工程B使警告数量降低了20%,工程E只产生了2%的警告,降低了工具产生警告的数量,为开发人员提供更多的信息来区分此警告是否是真正的安全威胁。 展开更多
关键词 Coverity Findbugs XSS 漏洞
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机群环境T.cover最优投资决策模型的并行化研究
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作者 郑晓薇 刘青昆 李天琦 《计算机工程与应用》 CSCD 北大核心 2006年第6期107-109,共3页
在Linux操作系统和MPI并行环境下,由多台微机组成的机群上,实现了分布式决策支持系统中T.cover最优投资决策模型的并行化。在并行算法中采用组消息通讯和阻塞同步的方式实现了投资决策数据的并行计算。
关键词 机群 并行计算 MPI T.cover最优投资决策模型
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Scope of Earth Science Frontiers
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《地学前缘》 EI CAS CSCD 北大核心 2007年第3期63-63,共1页
Earth Science Frontiers is a bi-monthly publication in Chinese with English abstracts for most papers; a few articles are published entirely in English. It is a medium for the publication of original and forefront res... Earth Science Frontiers is a bi-monthly publication in Chinese with English abstracts for most papers; a few articles are published entirely in English. It is a medium for the publication of original and forefront research and high quality reviews covering recent advances in all fields of Earth Sciences. Each issue is devoted to a single topic and edited by an authority in that field. 展开更多
关键词 AUTHORITY devoted covering ABSTRACTS ADVANCES entirely
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GEOLOGY, ENVIRONMENTAL CHANGE IN WATER RESOURCES, ZAGROS-IRAN
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作者 Bijan Aghili 《中国岩溶》 CAS CSCD 北大核心 1992年第S1期167-179,共13页
The water quality of many karst formations in southern Zagros macrotectonical unit is related to natural geological and hydrogeological conditions and ground water mismanagement. Evaporatic sediments inciuding: gypsum... The water quality of many karst formations in southern Zagros macrotectonical unit is related to natural geological and hydrogeological conditions and ground water mismanagement. Evaporatic sediments inciuding: gypsum, anhydrite, salt, marl, and marly limestone are existed in some formations such as: Kazhdomi, Pabdeh-Gurpi, Gachsaran, Mishan and Agha Jari formations. This situation makes the covering layers of the karst formations changing the water quality by rainfall and runoff infiltration The most important factors that strikingly differ the water quality are the distribution of innumerable salt domes (180 diapirs between 6-200 km^2) and the out gassing of oil reservoir and geothermal effects in the karst cerranes of southern Zagros range. 展开更多
关键词 formations KARST reservoir LIMESTONE covering SHALE RESERVES DOMES CARBONATE dissolution
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