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Threshold pressure gradient of fluid flow through multi-porous media in low and extra-low permeability reservoirs

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Science China Earth Sciences 2014年第8期57卷 2808-2818页

作者： DOU HongEn ma shiying ZOU CunYou YAO ShangLin Research Institute of Petroleum Exploration & Development PetroChina

After analyzing many studies of fluid flow theory of multi-porous media in low and extra-low permeability reservoirs and the numerical simulation of non-Darcy flow, we found that a negative flow rate occurs in the existing non-Darcy flow equation, which is unreasonable. We believe that the existing equation can only be considered as a discriminant to judging Darcy flow or non-Darcy flow, and cannot be taken as a fluid flow governing equation of multi-porous media. Our analysis of the experimental results shows that the threshold pressure gradient(TPG) of low and extra-low permeability reservoirs is excessively high, and does not conform to fluid flow through multi-porous media in the actual reservoir situation. Therefore, we present a reasonable TPG ranging from 0.006 to 0.04 MPa/m at the well depth of 1500 m and oil drainage distance of 500 m. The results of our study also indicate that the non-Darcy flow phenomenon will disappear when the TPG reaches a certain value. In addition, the TPG or non-Darcy flow in low and extra-low permeability reservoirs does not need to be considered in the productivity prediction and reservoir numerical simulation. At present, the black oil model or dual-porous media is suitable for simulating low and extra-low permeability reservoirs.

关键词：特低渗透油藏启动压力梯度流体流动多孔隙介质油藏数值模拟非达西渗流多孔介质模拟理论

Modeling cascading failures and mitigation strategies in PMU based cyber-physical power systems

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Journal of Modern Power Systems and Clean Energy 2018年第5期6卷 944-957页

作者： Yuqi HAN Chuangxin GUO shiying ma Dunwen SONG College of Electrical Engineering Zhejiang University China Electric Power Research Institute

This paper presents a model of cascading failures in cyber-physical power systems(CPPSs) based on an improved percolation theory, and then proposes failure mitigation strategies. In this model, the dynamic development of cascading failures is divided into several iteration stages. The power flow in the power grid, along with the data transmission and delay in the cyber layer, is considered in the improved percolation theory. The interaction mechanism between two layers is interpreted as the observability and controllability analysis and data update analysis influencing the node state transformation and security command execution. The resilience indices of the failures reflect the influence of cascading failures on both topological integrity and operational state. The efficacy of the proposed mitigation strategies is validated, including strategies to convert some cyber layer nodes into autonomous nodes and embed unified power flow controller(UPFC) into the physical layer. The results obtained from simulations of cascading failures in a CPPS with increasing initial failure sizes are compared for various *** cascading failures can be separated into rapid and slow processes. The interdependencies and gap between the observable and controllable parts of the physical layer with the actual physical network are two fundamental reasons for first-order transition failures. Due to the complexity of the coupled topological and operational relations between the two layers, mitigation strategies should be simultaneously applied in both layers.

关键词： Cyber physical power system Cascading failure Improved percolation theory Interdependent network Mitigation strategy

U-Pb zircon geochronology of basaltic pyroclastic rocks from the basement beneath the Xisha Islands in the northwestern South China Sea and its geological significance

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Acta Oceanologica Sinica 2024年第2期43卷 83-93页

作者： Yu Zhang Kefu Yu shiying Li Guangxi Laboratory on the Study of Coral Reefs in the South China Sea Guangxi UniversityNanning 530004China Coral Reef Research Center of China Guangxi UniversityNanning 530004China School of marine Sciences Guangxi UniversityNanning 530004China Key Laboratory of Ocean and marginal Sea Geology South China Sea Institute of OceanologyChinese Academy of ScienceGuangzhou 510301China

As one of the micro-blocks dispersed in the South China Sea(SCS), the basement of the Xisha Islands has rarely been drilled because of the thick overlying Cenozoic sediments, which has led to a confused understanding of the pre-Cenozoic basement of the Xisha Islands. Well CK-1, a kilometer-scale major scientific drill in the Xisha Islands in the northwestern SCS, penetrated thick reefal limestone(0–888.4 m) and the underlying basement rocks(888.4–901.4 m). In this study, we present the zircon U-Pb ages of basement basaltic pyroclastic rocks from Well CK-1 in the Xisha Islands of the northwestern SCS to investigate the basement nature of the Xisha microblock. The basement of Well CK-1 consists of basaltic pyroclastic rocks on the seamount. The zircon grains yielded apparent ages ranging from ca. 2 138.9 ma to ca. 36 ma. The old group of zircon grains from Well CK-1 was considered to be inherited zircons. Two Cenozoic zircons gave a weighted mean 206Pb/238U age of(36.3 ± 1.1) ma,Mean Squared Weighted Deviations(MSWD) = 1.2, which may represent the maximum age of the volcano eruption. The Yanshanian inherited zircons(116.9–105.7 ma and 146.1–130.2 ma) from Well CK-1 are consistent with the zircons from Well XK-1, indicating that the basement of Chenhang Island may be similar to that of Well XK-1. We propose that the Xisha micro-block may have developed on a uniform Late Jurassic metamorphic crystalline basement, intruded by Cretaceous granitic magma.

关键词： South China Sea Xisha Islands basaltic pyroclastic rocks zircon

Genomic alterations in oral multiple primary cancers

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International Journal of Oral Science 2024年第1期16卷 145-153页

作者： Wen Wang Qian Wang shiying Sun Pengfei Zhang Yuyu Li Weimin Lin Qiwen Li Xiao Zhang Zhe ma Haiyan Lu Hebei Key Laboratory of Stomatology Hebei Clinical Research Center for Oral DiseasesHebei Medical UniversityShijiazhuangChina Department of Orthodontics School and Hospital of StomatologyHebei Medical UniversityShijiazhuangChina State Key Laboratory of Oral Diseases&National Center for Stomatology&National Clinical Research Center for Oral Diseases&West China Hospital of Stomatology Sichuan UniversityChengduChina Department of Preventive Dentistry School and Hospital of StomatologyHebei Medical UniversityShijiazhuangHebeiChina

Oral squamous cell carcinoma (OSCC) is the predominant type of oral cancer, while some patients may develop oral multiple primary cancers (MPCs) with unclear etiology. This study aimed to investigate the clinicopathological characteristics and genomic alterations of oral MPCs. Clinicopathological data from patients with oral single primary carcinoma (SPC, n=202) and oral MPCs (n=34) were collected and compared. Copy number alteration (CNA) analysis was conducted to identify chromosomal-instability differences among oral MPCs, recurrent OSCC cases, and OSCC patients with lymph node metastasis. Whole-exome sequencing was employed to identify potential unique gene mutations in oral MPCs patients. Additionally, CNA and phylogenetic tree analyses were used to gain preliminary insights into the molecular characteristics of different primary tumors within individual patients. Our findings revealed that, in contrast to oral SPC, females predominated the oral MPCs (70.59%), while smoking and alcohol use were not frequent in ***, long-term survival outcomes were poorer in oral MPCs. From a CNA perspective, no significant differences were observed between oral MPCs patients and those with recurrence and lymph node metastasis. In addition to commonly mutated genes such as CASP8, TP53 and MUC16, in oral MPCs we also detected relatively rare mutations, such as HS3ST6 and RFPL4A. Furthermore, this study also demonstrated that most MPCs patients exhibited similarities in certain genomic regions within individuals, and distinct differences of the similarity degree were observed between synchronous and metachronous oral MPCs.

关键词： alterations metastasis oral

Virus-Host Interactions Drive Contrasting Bacterial Diel Dynamics in the Ocean

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Research 2024年第2期6卷 389-399页

作者： Xiaowei Chen Chen Hu Wei Wei Yunlan Yang markus G.Weinbauer Hongbo Li shiying Ren Ruije ma YVibin Huang Tingwei Luo Nianzhi Jiao Rui Zhang State Key Laboratory of marine Environmental Science College of Ocean and Earth SciencesFujian Key Laboratory of Marine Carbon SequestrationXiamen UniversityXiamen 361102PR China College of the Environment and Ecology Xiamen UniversityXiamen 361102PR China Research Center for Environmental Ecology and Engineering School of Environmental Ecology and Biological EngineeringWuhan Institute of TechnologyWuhan 430205PR China Sorbonne Universités UPMCUniversitéParis 06CNRSLaboratoire d'Oceanographie de Villefranche(LOV)Villefranche-sur-Mer 06230France National marine Environmental Monitoring Center Ministry of Ecological EnvironmentDalian 116023PR China Department of Ocean Sciences University of CaliforniaSanta CruzCAUSA NOAA/OAR Pacific marine Environmental Laboratory SeattleWAUSA Institute for Advanced Study Shenzhen UniversityShenzhen 518055PR China

marine organisms perform a sea of diel *** diel dynamics have been shown to be driven by light,energy resources,circadian rhythms,and the coordinated coupling of photoautotrophs and heterotrophic ***,we explore the diel fluctuation of viral production and decay and their impact on the total and active bacterial community in the coastal and open seawaters of the South China *** results showed that the night-production diel pattern of lytic viral production was concurrent with the lower viral decay at night,contributing to the accumulation of the viral population size during the night for surface *** diel variations in bacterial activity,community composition,and diversity were found highly affected by viral *** was revealed by the finding that bacterial community diversity was positively correlated to lytic viral production in the euphotic zone of the open ocean but was negatively related to lysogenic viral production in the coastal *** distinct but contrasting correlations suggest that viral life strategies can not only contribute to diversifying bacterial community but also potentially piggyback their host to dominate bacterial community,suggesting the tightly synchronized depth-dependent and habitat-specific diel patterns of virus-host *** further implies that viruses serve as an ecologically important driver of bacterial diel dynamics across the ocean,highlighting the viral roles in bacterial ecological and biogeochemical processes in the ocean.

关键词： coastal ocean marine

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基于广域响应的电力系统暂态失步判据综述

电网技术 2022年第7期46卷 2677-2689页

作者：朱存浩马世英郑超李鹏华陈长胜中国电力科学研究院有限公司北京市海淀区100192

广域测量技术为暂态稳定判别方法的应用提供了契机。结合电力系统暂态稳定评估的基本原理,概述了基于相量角度差、暂态能量函数、扩展等面积准则、响应轨迹特征和人工智能等5种类型的广域暂态失步判据的研究现状,探讨了各种判据在发展... 详细信息

广域测量技术为暂态稳定判别方法的应用提供了契机。结合电力系统暂态稳定评估的基本原理,概述了基于相量角度差、暂态能量函数、扩展等面积准则、响应轨迹特征和人工智能等5种类型的广域暂态失步判据的研究现状,探讨了各种判据在发展应用中需解决的问题。从准确性、预测性、稳定裕度定量化、适应性4个方面,对比了以上各种类型广域暂态失步判据的特点,并分析展望了各类判据的重点研究与突破方向,为相关研究的进一步开展提供有益借鉴。

关键词：暂态失步判据广域响应信息能量函数扩展等面积准则响应轨迹特性

基于关键支路受扰轨迹凹凸性的暂态稳定判别及紧急控制

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中国电机工程学报 2016年第10期36卷 2600-2610页

作者：郑超苗田马世英中国电力科学研究院北京市海淀区100192 华北电力大学电气与电子工程学院河北省保定市071003

基于局部受扰信息,判别大扰动冲击下互联电网暂态功角稳定性,具有本地量测信息量少、实时响应实时判别、稳定判别计算量小等突出技术优点。该文首先分析了稳定与失稳两种情况下,发电机相轨迹与网络交流支路相轨迹几何特征的一致性;提出... 详细信息

基于局部受扰信息,判别大扰动冲击下互联电网暂态功角稳定性,具有本地量测信息量少、实时响应实时判别、稳定判别计算量小等突出技术优点。该文首先分析了稳定与失稳两种情况下,发电机相轨迹与网络交流支路相轨迹几何特征的一致性;提出了基于临界断面中交流关键支路受扰相轨迹凹凸性的暂态稳定判别新方法;通过与快速失步解列装置整定参数的协调配合,获得了具备工程实施条件的时间裕度,在防控暂态稳定的第二道防线失效时,可作为避免失稳的紧急追加控制措施;交直流混联外送电网和特高压跨大区互联电网仿真结果,均验证了稳定判别方法和紧急追加控制的有效性。

关键词：暂态稳定局部受扰信息相轨迹凹凸性稳定判别紧急追加控制协调配合

DSG型抛物面槽式太阳能热电站热力系统实时动态仿真模型研究

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中国电机工程学报 2014年第11期34卷 1787-1798页

作者：崔凝徐国强马士英北京航空航天大学北京市海淀区100191 保定华仿科技有限公司河北省保定市071051

采用模块化建模方法研究了无蓄热装置再循环方式直接产生蒸汽型抛物面槽式太阳能热动力发电站(solar thermal power plant using direct steam generation in parabolic trough collectors filed,DSG-PTCs-STTP)热力系统动态仿真模型。依照守恒定律和热力学、传热学、流体力学等基本关系式,在一定简化条件下,研究了抛物面槽式聚光集热系统的聚光器、预热段、蒸发段、过热段及汽水缓冲分离器的数学模型,结合其他已有的仿真模型(如流体网络、汽轮机、凝汽器、除氧器、水泵、发电励磁等过程及设备模型等),建立了完整的DSG-PTCs-STTP热力系统实时动态仿真模型。仿真试验表明所开发的仿真模型能够正确反映研究对象热力系统动态特性和全工况运行过程,模型运算稳定可靠。可用于DSG-PTCs-STTP机组实时仿真系统的开发,还可为机组运行特性研究和控制系统验证提供良好的非线性对象模型。

关键词：直接产生蒸汽抛物面槽式聚光集热太阳能热力电站动态模型仿真

近振荡中心直流逆变站对系统阻尼的影响及优化措施

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中国电机工程学报 2015年第19期35卷 4895-4905页

作者：郑超马世英盛灿辉中国电力科学研究院北京市海淀区100192

我国地域辽阔,一次能源与负荷中心呈逆向分布特征。特高压直流跨区送电,并经特高压交流接续送电,是实现电力大容量、远距离、经济高效输送的重要方式,将成为交直流混联电网的典型格局之一。大扰动冲击下,与振荡中心近电气距离的大容量... 详细信息

我国地域辽阔,一次能源与负荷中心呈逆向分布特征。特高压直流跨区送电,并经特高压交流接续送电,是实现电力大容量、远距离、经济高效输送的重要方式,将成为交直流混联电网的典型格局之一。大扰动冲击下,与振荡中心近电气距离的大容量直流逆变站,其功率动态变化,会对系统振荡阻尼特性产生影响。该文研究了交流电压大幅波动条件下,直流逆变站非线性无功特性;从并联无功补偿支路提供振荡正阻尼条件和振荡等面积原理两个方面,揭示了直流逆变站弱化振荡阻尼的机制;基于低压限流单元(voltage dependent current order limiter,VDCOL)限流特性曲线对逆变站无功特性的影响分析,提出改善混联系统振荡阻尼的优化措施。准东—重庆?1 100 k V/10 000 MW特高压交直流混联电网大扰动时域仿真结果,验证了措施对抑制混联电网低频振荡的有效性。

关键词：特高压直流逆变站功率特性振荡中心振荡阻尼