期刊文献+
共找到15,674篇文章
< 1 2 250 >
每页显示 20 50 100
A NovelMethod for Determining Tourism Carrying Capacity in a Decision-Making Context Using q−Rung Orthopair Fuzzy Hypersoft Environment
1
作者 Salma Khan Muhammad Gulistan +2 位作者 NasreenKausar Seifedine Kadry Jungeun Kim 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第2期1951-1979,共29页
Tourism is a popular activity that allows individuals to escape their daily routines and explore new destinations for various reasons,including leisure,pleasure,or business.A recent study has proposed a unique mathema... Tourism is a popular activity that allows individuals to escape their daily routines and explore new destinations for various reasons,including leisure,pleasure,or business.A recent study has proposed a unique mathematical concept called a q−Rung orthopair fuzzy hypersoft set(q−ROFHS)to enhance the formal representation of human thought processes and evaluate tourism carrying capacity.This approach can capture the imprecision and ambiguity often present in human perception.With the advanced mathematical tools in this field,the study has also incorporated the Einstein aggregation operator and score function into the q−ROFHS values to supportmultiattribute decision-making algorithms.By implementing this technique,effective plans can be developed for social and economic development while avoiding detrimental effects such as overcrowding or environmental damage caused by tourism.A case study of selected tourism carrying capacity will demonstrate the proposed methodology. 展开更多
关键词 q−Rung orthopair fuzzy hypersoft set DECISION-MAKING tourism carrying capacity aggregation operator
下载PDF
The Quest for Haven in Sister Carrie
2
作者 ZHANG Yi-wen 《Journal of Literature and Art Studies》 2024年第5期315-324,共10页
This essay analyses Theodore Dreiser’s Sister Carrie through the lens of cultural studies,examining the portrayal of domesticity and the quest for an ideal home in late-nineteenth-century America.It explores the comp... This essay analyses Theodore Dreiser’s Sister Carrie through the lens of cultural studies,examining the portrayal of domesticity and the quest for an ideal home in late-nineteenth-century America.It explores the complex relationships between the main characters,Carrie and Hurstwood,and their families,as well as their struggles with materialism and alienation.Through close analysis of societal context,the characters’familial backgrounds and emotional yearnings,the essay delves into the characters’longing for stability and belonging and their journey toward understanding the true essence of dwelling amidst the changing urban landscape.It argues that Dreiser’s novel critiques the superficial pursuit of material comforts and highlights the importance of introspection and self-discovery in finding lasting happiness amidst societal turmoil.Ultimately,through the prism of domesticity,the essay delves into broader themes of identity,belonging,and existential fulfillment in a heartless society marked by materialism and alienation. 展开更多
关键词 Theodore Dreiser Sister Carrie HOME DOMESTICITY belonging
下载PDF
Analysis of Pollutant Load Carrying Capacity of the River Tapi Using QUAL2Kw for Surat City
3
作者 Hiralkumari B. Patel Namrata D. Jariwala 《Journal of Environmental Protection》 CAS 2023年第2期96-107,共12页
River Tapi is the prime water body for Surat city, Gujarat, India. On a long stretch of 22.39 km in Surat city (Kamrej to Causeway) of the Tapi river, there are many identified and non-identified discharge points avai... River Tapi is the prime water body for Surat city, Gujarat, India. On a long stretch of 22.39 km in Surat city (Kamrej to Causeway) of the Tapi river, there are many identified and non-identified discharge points available. Excessive discharge from these points restricts the efficiency of the self-purification process which ultimately degrades the river water quality. In this paper, an attempt has been made to estimate the pollutant load-carrying capacity at different segments of the river Tapi using the QUAL2Kw tool. The study has been undertaken with different scenarios: First, the QUAL2Kw model was trained with available river water quality and hydraulic data of the Tapi river in which the complete river segment was divided into 21 reaches. The model was calibrated and validated with the actual concentrations of the pollutants entering. In the second phase, all the point source, non-point source, and headwater characteristics were considered and the pollutant load-carrying capacity of the river in terms of BOD, ISS, and N-nitrate was found. In the third phase, all the sources of pollutants entering the river have been removed and only headwater characteristics were considered for the study. The results indicate that reach no. 21 (21.23ºN, 72.82ºE) has the maximum load-carrying capacity of Biochemical Oxygen Demand (BOD) up to 2057.7 kg/day, Inorganic Suspended Solids (ISS) up to 85633.8 kg/day, and Nitrate (NO<sub>3</sub>) up to 31688.8 kg/day. However, reach no. 4 has the minimum load carrying capacity of BOD up to 1088.1 kg/day, reach 8 carries a minimum of ISS 205341.6 kg/day and NO3 10215.57 kg/day. 展开更多
关键词 Load carrying Capacity River Water Quality QUAL2Kw Tapi River
下载PDF
Analysis of the Concept of Environmental Carrying Capacity
4
作者 XU Xiangyu 《Journal of Landscape Research》 2023年第3期79-84,共6页
From the concept of carrying capacity proposed in the early 20th century to as an important tool for describing development constraints in the 21st century,many scholars have conducted extensive and detailed research ... From the concept of carrying capacity proposed in the early 20th century to as an important tool for describing development constraints in the 21st century,many scholars have conducted extensive and detailed research on carrying capacity at different levels,but the carrying capacity system has not yet formed a unified theoretical and methodological system.By summarizing and analyzing the existing literature,based on the viewpoints of Mr.Gao Jixi and Mr.Zeng Weihua,the relationship between different mainstream carrying capacities is analyzed,and finally a system for summarizing the elements of different carrying capacities is provided,which to some extent serves as a reference for scholars who have just come into contact with the concept of carrying capacity.It is thought that:①the research on ecological carrying capacity covers the scope of cities,and the research at the urban level complements the neglected and insufficient areas of ecological research.②The main difference among ecological carrying capacity,urban comprehensive carrying capacity and resource environment carrying capacity lies in the different research scopes.In the mainstream view,environmental carrying capacity and resource carrying capacity are summarized under the framework of different research scopes.Water environment carrying capacity,land resource carrying capacity and other single factor carrying capacity are special in-depth studies of environment and resource carrying capacity.③Ecological carrying capacity at the ecological level includes environmental carrying capacity and resource carrying capacity.At the urban level,urban ecology is equivalent to urban environment to a certain extent,and resources can be classified into urban environmental carrying capacity as an environmental element. 展开更多
关键词 Environmental carrying capacity Ecological carrying capacity Resource carrying capacity
下载PDF
Integrated water risk early warning framework of the semi-arid transitional zone based on the water environmental carrying capacity (WECC)
5
作者 XIE Yuxi ZENG Weihua QIU Jie 《Journal of Arid Land》 SCIE CSCD 2023年第2期145-163,共19页
Water risk early warning systems based on the water environmental carrying capacity(WECC)are powerful and effective tools to guarantee the sustainability of rivers.Existing work on the early warning of WECC has mainly... Water risk early warning systems based on the water environmental carrying capacity(WECC)are powerful and effective tools to guarantee the sustainability of rivers.Existing work on the early warning of WECC has mainly concerned the comprehensive evaluation of the status quo and lacked a quantitative prejudgement and warning of future overload.In addition,existing quantitative methods for short-term early warning have rarely focused on the integrated change trends of the early warning indicators.Given the periodicity of the socioeconomic system,however,the water environmental system also follows a trend of cyclical fluctuations.Thus,it is meaningful to monitor and use this periodicity for the early warning of the WECC.In this study,we first adopted and improved the prosperity index method to develop an integrated water risk early warning framework.We also constructed a forecast model to qualitatively and quantitatively prejudge and warn about the development trends of the water environmental system.We selected the North Canal Basin(an essential connection among the Beijing-Tianjin-Hebei region)in China as a case study and predicted the WECC in 25 water environmental management units of the basin in 2018–2023.We found that the analysis of the prosperity index was helpful in predicting the WECC,to some extent.The result demonstrated that the early warning system provided reliable prediction(root mean square error of 0.0651 and mean absolute error of 0.1418),and the calculation results of the comprehensive early warning index(CEWI)conformed to the actual situation and related research in the river basin.From 2008 to 2023,the WECC of most water environmental management units in the basin had improved but with some spatial differences:the CEWI was generally poor in areas with many human disturbances,while it was relatively good in the upstream regions with higher forest and grass covers as well as in the downstream areas with larger water volume.Finally,through a sensitivity analysis of the indicators,we proposed specific management measures for the sustainability of the water environmental system in the North Canal Basin.Overall,the integrated water risk early warning framework could provide an appropriate method for the water environmental administration department to predict the WECC of the basin in the future.This framework could also assist in implementing corresponding management measures in advance,especially for the performance evaluation and the arrangement of key short-term tasks in the River Chief System in China. 展开更多
关键词 water risk early warning system water environmental carrying capacity prosperity index water management North Canal(Beiyun River)
下载PDF
Evaluation of Water Resources Carrying Capacity in Gansu Section of Yellow River Basin Based on Fuzzy Comprehensive Evaluation Model
6
作者 Shuanbao LIN 《Meteorological and Environmental Research》 CAS 2023年第4期42-45,49,共5页
As a basic natural resource and strategic economic resource,the development and utilization of water resources is an important issue related to the national economy and people's livelihood.How to scientifically ev... As a basic natural resource and strategic economic resource,the development and utilization of water resources is an important issue related to the national economy and people's livelihood.How to scientifically evaluate the water resources carrying capacity is the premise to improve the regional water resources carrying capacity and ensure the regional water security.The Gansu section of the Yellow River basin is an important water conservation and recharge area.Whether the water resources in this area can ensure the normal operation of the ecosystem and whether it can carry the sustainable development of social economy is the key to realize the high-quality development of the Yellow River basin.In this study,from the three dimensions of water consumption per capita,water consumption of 10000 yuan GDP and ecological water use rate,by constructing the evaluation index system and index grading standard of water resources carrying capacity,the fuzzy comprehensive evaluation model was used to evaluate the water resources carrying capacity of Gansu section of the Yellow River Basin,in order to provide theoretical decision-making basis for the comprehensive development,utilization and planning management of water resources in Gansu section of the Yellow River basin and even the whole basin,and help the high-quality development of the Yellow River basin. 展开更多
关键词 Fuzzy comprehensive evaluation model Water resources carrying capacity EVALUATION Yellow River basin Gansu section
下载PDF
Exploring the Goal Synergy between the Ecological Carrying Capacity of Miyun District and the Development of the Ecological Home-stay Industry in Beijing
7
作者 ZHANG Qilun CAO Jinglong XU Zhiyong 《Journal of Landscape Research》 2023年第2期45-48,53,共5页
Green construction in culture and environmental protection will be the development trend in a long run,the urban and suburban area will be ecologically developed as well.Rural revitalization must adhere to the positio... Green construction in culture and environmental protection will be the development trend in a long run,the urban and suburban area will be ecologically developed as well.Rural revitalization must adhere to the position of historical progress theory and modern concepts,innovate spatial layout,optimize ecological resources,and appropriately determine its historical significance and sustainable development responsibility with reasonable value orientation and environmental ecological carrying capacity for local ecological construction.In order to achieve this responsibility,the authors must expand the dimensions to consider more relevant factors.The guarantee of ecological carrying capacity is an important means to ensure the promotion of ecological civilization.This paper aims to integrate and regulate the goal synergy of the cultural development of the home-stay industry in Miyun District of Beijing by means of the innovative model of sustainable economic development of cultural ecology,ecological people,ecological health preservation and rich home-stay ecological elements.Assuming that the role of the former in promoting the latter can be expanded,then in the range of ecological and cultural towns(conceptual model)that maintain a certain tolerance of ecological carrying capacity,as a characteristic home-stay industry in Miyun,there will be some effective growth,so the integration and development of multiple cultural genes and elements must be the ecological and cultural town model under the enhanced multi-factor aggregation effect,(See the ecological environment carrying capacity development goal A:A=B12345+C1234567 later).This article will explain that the development goals of Miyun's ecological culture and the ecological homestay industry are coordinated,and the two are mutually raised in the same direction. 展开更多
关键词 Ecological carrying capacity Coordinated development goals of ecological home-stay industry Goal synergy
下载PDF
新疆煤炭资源开发潜力与开发策略 被引量:1
8
作者 卞正富 张益东 +5 位作者 王猛 王长申 韩晓彤 牟守国 任清晨 李国栋 《煤炭学报》 EI CAS CSCD 北大核心 2024年第2期967-977,共11页
鉴于新疆煤炭资源赋存条件的独特性以及煤炭赋存区生态环境的脆弱性,科学开发新疆煤炭资源成为当务之急。为此,简要论述了新疆煤炭资源地质赋存条件、赋煤区水文地质条件、自然地理与生态环境条件,分析了新疆煤炭资源开发潜力。结果表明... 鉴于新疆煤炭资源赋存条件的独特性以及煤炭赋存区生态环境的脆弱性,科学开发新疆煤炭资源成为当务之急。为此,简要论述了新疆煤炭资源地质赋存条件、赋煤区水文地质条件、自然地理与生态环境条件,分析了新疆煤炭资源开发潜力。结果表明:新疆煤炭资源极为丰富,全区预测煤炭资源量2.19万亿t,占全国总预测储量的40%以上;新疆共有24个预测资源量超过100亿t的煤田,其中5个煤田预测资源量超过1 000亿t,8个煤田预测资源量在400亿~1 000亿t,11个煤田预测资源量在100亿~400亿t;潜在煤炭资源量中,1 000 m以下浅储量占比52.8%。新疆煤炭资源以低阶烟煤和中阶烟煤为主要煤阶,其次是中煤阶煤中的高阶烟煤,而低煤阶煤中的褐煤和中煤阶煤中的超高阶烟煤以及高煤阶煤中的无烟煤,分布范围和数量极为有限,所占资源总量的比例很低;综合考虑疆煤外运、疆电外送、西气东输以及本地煤化工产业规划,预计2035年新疆煤炭产能有望超8亿t。在此基础上,构建了生态环境承载力评价指标体系,对新疆规划建设的五大煤矿区生态环境承载力进行了评价,得出:新疆煤炭资源赋存区生态环境承载力整体处于中低水平,五大煤矿区生态环境承载力均值排序为伊犁(0.42)>库拜(0.38)>和丰(0.31)>准东(0.25)>吐哈(0.22),呈现出由西到东递减的趋势。针对新疆煤炭资源开发条件与潜力,提出了优化煤炭资源开发布局、推动开采技术升级、推进智能采矿技术、强化绿色开采理念、拓展煤炭多元化利用渠道等策略。 展开更多
关键词 新疆煤炭开发 潜力 生态承载力 开发策略
下载PDF
Demand Analysis and Solution Exploration on 5G Carrying Railway Operational Services
9
作者 LIU Ziyuan ZHOU Yanfang 《Chinese Railways》 2023年第1期18-24,共7页
Given the overwhelmed GSM-R network in China,the railway sector has turned to the public network to promote railway communication technologies.With 5G identified as the next-generation mobile communication network for... Given the overwhelmed GSM-R network in China,the railway sector has turned to the public network to promote railway communication technologies.With 5G identified as the next-generation mobile communication network for railways,China has proposed a holistic approach for the building of intelligent railway via 5G public network.Based on the characteristics of 5G and the classic services of railway,the paper proposes a categorized carrying scheme for railway in mobile communication network,as well as a graded scheme based on 5G-R.The paper then advises to accelerate the development of 5G-R equipment and adopt diverse mobile communication networks to carry railway business,which are of reference to future studies on the issue. 展开更多
关键词 5G-R GSM-R railway business communication requirements carrying scheme
下载PDF
黑土地保护视角下黑龙江省畜禽养殖环境效应分析 被引量:1
10
作者 姜冰 康祎梅 +1 位作者 李全峰 王晨 《农业资源与环境学报》 CAS CSCD 北大核心 2024年第3期592-605,共14页
为合理利用畜禽粪污资源,保护黑龙江省黑土地资源,优化农畜业生产布局,实现农牧业绿色发展,本研究基于2011—2020年统计数据及文献资料,测算了黑龙江省畜禽粪污排放情况,并据此分析黑龙江省畜禽粪污资源化利用潜力及畜禽养殖环境承载力... 为合理利用畜禽粪污资源,保护黑龙江省黑土地资源,优化农畜业生产布局,实现农牧业绿色发展,本研究基于2011—2020年统计数据及文献资料,测算了黑龙江省畜禽粪污排放情况,并据此分析黑龙江省畜禽粪污资源化利用潜力及畜禽养殖环境承载力。结果表明:从时间动态来看,2011—2020年,黑龙江省畜禽粪尿、粪尿养分、COD排放量均有小幅下降,降幅分别为3.68%、3.24%和5.82%;畜禽粪污的化肥替代潜力虽整体略有下降,但10年来均保持在35%以上,2020年化肥替代潜力已达到41.89%,具有较高的有机肥替代化肥潜力;黑龙江省畜禽粪污的能源潜力略有增长,但对煤炭的替代潜力呈下降趋势且替代作用并不显著,2020年畜禽粪污的沼气潜力为46.74亿m^(3),折合为标准煤仅占标准煤消费量的2.90%,能源潜力有待进一步开发利用;黑龙江省畜禽粪尿、粪尿氮、粪尿磷的耕地负荷均未超载,无养殖环境风险,畜禽养殖环境容量的空间剩余呈上升趋势,剩余约2/3,以氮为基准计算,余量为13006.13万头猪当量,以磷为基准计算,余量为8463.19万头猪当量,具有较大养殖潜力。从空间分布来看,黑龙江省各地区畜禽粪污排放及资源化利用潜力存在明显差异,哈尔滨市、齐齐哈尔市、绥化市、大庆市以及佳木斯市等畜禽养殖集聚区的畜禽粪尿资源丰富,畜禽粪污的替代化肥潜力、能源潜力及畜禽养殖发展潜力较大。 展开更多
关键词 畜禽粪尿 资源化利用 替代化肥潜力 能源潜力 环境承载力 黑土地保护
下载PDF
嵌套加强的LQ550高强冷弯薄壁C型钢连续檩条受力性能研究 被引量:2
11
作者 袁焕鑫 房铭坤 +2 位作者 杜新喜 柯善夫 谭美超 《建筑结构》 北大核心 2024年第1期66-71,共6页
为提高LQ550级高强冷弯薄壁C型钢连续檩条的承载能力,采用在支座处嵌套的方法来加强连续檩条。对未加强和采用两种嵌套方式加强的檩条共7组试件进行三点受弯试验,得到了试件的承载性能和破坏形态,试验结果表明加强后的试件出现跨中局部... 为提高LQ550级高强冷弯薄壁C型钢连续檩条的承载能力,采用在支座处嵌套的方法来加强连续檩条。对未加强和采用两种嵌套方式加强的檩条共7组试件进行三点受弯试验,得到了试件的承载性能和破坏形态,试验结果表明加强后的试件出现跨中局部屈曲和嵌套端部局部屈曲两种破坏形态。采用ABAQUS软件建立了非线性有限元模型对嵌套加强的檩条进行数值模拟,有限元分析得到的承载力和破坏形态与试验结果吻合良好,验证了有限元模型的准确性。基于验证的有限元模型,分析了两种嵌套方式和不同嵌套长度对檩条承载力的提升,且表明嵌套檩条的长度宜取为连续檩条跨度的1/5~1/4。 展开更多
关键词 高强钢 冷弯薄壁C型钢 连续檩条 嵌套加强 受力性能
下载PDF
基于系统动力学模型的郑州市水资源承载力动态模拟
12
作者 李铭 李想 +3 位作者 牛超杰 全李宇 赵连军 胡彩虹 《中国农村水利水电》 北大核心 2024年第6期49-55,63,共8页
水资源问题制约着缺水城市的可持续发展,近年来郑州市社会经济高速发展,其水资源有限的现状与用水需求快速增长之间的矛盾愈加凸显。为科学研究郑州市水资源承载力远期发展情况,根据郑州市经济社会现状的水资源供需和发展状况,采用多系... 水资源问题制约着缺水城市的可持续发展,近年来郑州市社会经济高速发展,其水资源有限的现状与用水需求快速增长之间的矛盾愈加凸显。为科学研究郑州市水资源承载力远期发展情况,根据郑州市经济社会现状的水资源供需和发展状况,采用多系统综合的系统动力学方法(System Dynamics,SD),结合水资源、生态、经济社会、水利工程四个子系统,构建郑州市水资源承载力研究的SD模型。将2010-2019年的历史数据与SD方法的模拟数据进行比较,平均误差均小于10%,具有较高的可信度,可用来预测郑州市未来的水资源承载力发展情况。在此基础上,通过设定现状延续、控污节流、开源控污和开源节流4种不同方案,对2020-2030年水资源承载力系数进行动态模拟预测。结果表明:2030年4种方案下的水资源承载力系数分别为1.24、1.18、1.00、0.89,现状延续和控污节流方案下的郑州市水资源承载力随着时间的推移呈现严重超载状态,无法承载郑州市经济社会的快速发展;开源控污方案在预测期内的水资源承载力超载状态会对经济社会发展产生较大阻力。故开源节流方案为最佳方案,水资源承载力系数小于1,在研究期内未出现超载状态,可有利缓解郑州市的缺水状况,促进经济社会的发展。结合4种方案的优点,提出有利于郑州市水资源可持续发展的建议与对策。 展开更多
关键词 水资源承载力 系统动力学模型 郑州市 水资源承载力系数
下载PDF
汶川震区山洪灾害场次洪水最大携沙量预测模型
13
作者 许懿娜 段乐 +5 位作者 刘超 聂锐华 李乃稳 刘秀菊 任妮 鲁恒 《时空信息学报》 2024年第2期216-228,共13页
汶川地震后,震区产生了大量松散堆积体,受强降水影响产生了破坏性更强的山洪灾害,加剧了灾害的危险性,增加了灾害防治的困难度,研究震区山洪灾害可为评估灾害的风险性及后续的管理提供依据。本研究以66处历史山洪灾害作为样本数据,进行... 汶川地震后,震区产生了大量松散堆积体,受强降水影响产生了破坏性更强的山洪灾害,加剧了灾害的危险性,增加了灾害防治的困难度,研究震区山洪灾害可为评估灾害的风险性及后续的管理提供依据。本研究以66处历史山洪灾害作为样本数据,进行可量算影响因子的相关性分析,揭示山洪灾害的携沙量影响机制,确定流域面积、主沟长度、相对高差、物源量四个影响因子作为主控因子,基于SPSS进行非线性回归分析,建立了基于场次洪水最大携沙量及最大携沙距离的估算模型,并选取了汶川县和都江堰市的共23处山洪水沙灾害数据进行了模型的验证且与其他模型对比。结果表明,本研究建立的模型可靠性好,精度更高。研究成果有助于预测汶川震区潜在的山洪水沙灾害区域,为山洪水沙灾害的风险评估提供依据。 展开更多
关键词 汶川震区 山洪灾害 携沙量 最大携沙距离 预测模型
下载PDF
基于FPGA的单光子时间数字转换器设计
14
作者 何继爱 辛家乐 石麟泰 《电子测量技术》 北大核心 2024年第5期16-21,共6页
针对单光子计数器对高速飞行光子时间测量的高分辨率要求,传统的TDC在时间测量上存在误差较大的不足。本文设计了一种利用FPGA内部逻辑延迟单元Carry4级联构建延迟链的TDC。该方法首先使用子链平均的方式进行数据采样,避免数据“气泡”... 针对单光子计数器对高速飞行光子时间测量的高分辨率要求,传统的TDC在时间测量上存在误差较大的不足。本文设计了一种利用FPGA内部逻辑延迟单元Carry4级联构建延迟链的TDC。该方法首先使用子链平均的方式进行数据采样,避免数据“气泡”。其次,结合码密度测试和bin-by-bin校准将各级延迟单元宽度校准至接近均匀宽度,提高系统的测量精度。最后,通过Vivado软件仿真并烧录至ZYNQ7000进行板级测试,实验结果表明,该TDC能够在3 ns的动态时间范围内实现时间分辨率10.91 ps,差分非线性(DNL)范围为[-0.75,1.01]LSB,积分非线性(INL)范围为[-1.74,2.19]LSB。 展开更多
关键词 FPGA 时间数字转换 carry4 码密度测试 差分非线性 积分非线性
下载PDF
太阳成像仪镜筒舱内压力控制技术研究
15
作者 崔致和 孙冬花 +4 位作者 周明 陈联 齐润泽 李棉峰 成永军 《真空科学与技术学报》 CAS CSCD 北大核心 2024年第3期191-195,共5页
文章阐述了太阳成像仪镜筒舱内压力控制技术研究,主要包括限流小孔机械尺寸理论分析、慢速泄压阀设计、镜筒压力控制模拟测试等内容。目前,所研制的慢速泄压阀已顺利交付使用,并随46.5 nm极紫外太阳成像仪在中科院空间新技术试验卫星上... 文章阐述了太阳成像仪镜筒舱内压力控制技术研究,主要包括限流小孔机械尺寸理论分析、慢速泄压阀设计、镜筒压力控制模拟测试等内容。目前,所研制的慢速泄压阀已顺利交付使用,并随46.5 nm极紫外太阳成像仪在中科院空间新技术试验卫星上进行了搭载,实现了在轨顺利开机,验证了太阳成像仪镜筒舱内压力控制手段的正确性。 展开更多
关键词 镜筒 太阳成像仪 压力控制 在轨搭载
下载PDF
天然气井多相流强化携液理论及排液采气关键技术
16
作者 白博峰 田伟 +7 位作者 赵昆鹏 贾友亮 李丽 杨旭东 赵峥延 李旭日 沈志昊 刘磊 《西安交通大学学报》 EI CAS CSCD 北大核心 2024年第5期10-18,共9页
天然气田稳产是保障我国能源安全的重大需求,气井积液是制约稳产的瓶颈,排液采气是保障稳产的关键。我国60%气井因积液年均产气量递减23%以上,且积液井数以年均5%的速率快速递增。由于对气井多相流动特性认识不足,传统排液采气技术仅适... 天然气田稳产是保障我国能源安全的重大需求,气井积液是制约稳产的瓶颈,排液采气是保障稳产的关键。我国60%气井因积液年均产气量递减23%以上,且积液井数以年均5%的速率快速递增。由于对气井多相流动特性认识不足,传统排液采气技术仅适用于积液轻微的浅直井且排液率较低。研究团队近年来聚焦天然气井排液采气难题,构建了基于气液流动结构调控的强化携液理论,突破了经典临界流速携液理论仅适用于环雾状流的局限;发明了抗油耐矿化度泡沫排液、复杂井筒速度管柱排液、超声速喷嘴雾化排液、气举柱塞接力举升排液等适用气井不同积液状态的高效低成本排液采气系列关键技术。研究成果已推广至长庆气田、中外合作开发区等11个气区,累计应用近12000口气井,占我国积液气井总数的30%以上。 展开更多
关键词 多相流动 强化携液 排液采气 气田稳产 能源安全
下载PDF
面向起重机结构承载能力评估的数字孪生系统构建方法
17
作者 董青 胡双贤 +2 位作者 徐格宁 南方磊 戚其松 《计算机集成制造系统》 EI CSCD 北大核心 2024年第3期837-851,共15页
针对当前起重机本质安全所面临的监测力度差、能力指标单一、数据利用率不高导致承载能力评估效率低、评估结果不够全面的问题,本着“虚实互控-互调-互补”的思想,提出面向起重机结构承载能力评估的数字孪生系统构建方法。从设备服役场... 针对当前起重机本质安全所面临的监测力度差、能力指标单一、数据利用率不高导致承载能力评估效率低、评估结果不够全面的问题,本着“虚实互控-互调-互补”的思想,提出面向起重机结构承载能力评估的数字孪生系统构建方法。从设备服役场景出发,结合数字孪生五维模型,设计起重机结构承载能力数字孪生框架;以多指标下的结构承载能力动态综合评估方法为支撑,围绕虚实映射、数据交互与服务交互,分层分级阐述结构承载能力数字孪生系统构建方法;从模块内聚,功能集成的角度,搭建数字孪生系统平台。以YDC20/30轻小型移动式起重机为例,验证了所提方法及系统的有效性,为及时精准判断起重机服役过程中的安全性提供了一种新途径、新策略。 展开更多
关键词 数字孪生 移动式起重机 承载能力 综合评估 虚实映射
下载PDF
适配变压器全档位切换暂态分析的有载分接开关电路模型构建
18
作者 司马文霞 王大森 +3 位作者 杨鸣 李刚 厉璇 杨建琴 《高电压技术》 EI CAS CSCD 北大核心 2024年第2期478-488,I0001,I0002,共13页
有载分接开关(on-loadtap-changer,OLTC)是换流变压器的核心组件,其可靠切换过程关乎换流变的安全。然而目前国内在运特高压换流变用OLTC完全依赖进口,仿真获取OLTC不同运行状态的暂态特性数据是支撑OLTC关键电气参数设计与国产化制造... 有载分接开关(on-loadtap-changer,OLTC)是换流变压器的核心组件,其可靠切换过程关乎换流变的安全。然而目前国内在运特高压换流变用OLTC完全依赖进口,仿真获取OLTC不同运行状态的暂态特性数据是支撑OLTC关键电气参数设计与国产化制造的基础。经典的OLTC模型仅改变变压器变比或仅模拟单级档位切换过程,难以满足全档位电压调整与各级档位暂态特性数据同步获取的需求,导致OLTC设计优化、参数选型及故障分析缺乏足够的仿真数据支持。该文首先以真空OLTC为研究对象建立切换开关和极性开关等效电路模型,根据OLTC复杂的调压功能建立分层控制系统。其次,在PSCAD中搭建交流仿真系统,获取有载调压过程的暂态特性数据波形,与解析计算得到的电压和电流相比误差小于0.2%,证明该模型满足OLTC电磁暂态仿真研究的精度要求。最后,开展循环调压仿真,获得负载电压数据与波形。结果表明:该文提出的OLTC模型能够接收外部控制信号,进行全档位调压与极性转换仿真分析,能够为OLTC的调压研究、故障溯源分析和过渡电阻设计选型等提供基础模型。 展开更多
关键词 有载分接开关 极性开关 切换开关 恢复电压 承载电流
下载PDF
水资源刚性约束制度研究框架与展望 被引量:2
19
作者 左其亭 凌敏华 张羽 《水利水电快报》 2024年第3期6-11,共6页
实行水资源刚性约束制度是当前水资源管理制度领域的重大改革措施,也是推动相关国家战略实施、实现人水和谐共生的必然举措。梳理了水资源刚性约束制度的提出背景与历程,分析了水资源刚性约束制度的概念内涵,从指导思想、理论基础、技... 实行水资源刚性约束制度是当前水资源管理制度领域的重大改革措施,也是推动相关国家战略实施、实现人水和谐共生的必然举措。梳理了水资源刚性约束制度的提出背景与历程,分析了水资源刚性约束制度的概念内涵,从指导思想、理论基础、技术支撑、战略目标、研究内容和关键问题等6个方面构建了水资源刚性约束制度研究框架,从理论研究、技术研究、实践研究等3个方面对未来研究进行了展望,以期为水资源刚性约束制度相关研究提供理论和实践参考。 展开更多
关键词 水资源刚性约束 水资源管理 人水关系学 水资源承载能力
下载PDF
黑线姬鼠实验动物化研究进展
20
作者 金志民 李强 +2 位作者 鲁思含 孙悦 贾修歧 《天津农业科学》 CAS 2024年第5期24-30,共7页
自新冠肺炎疫情以来,全球以动物为媒介的传染病不断发生,人们需要更多种类的实验动物作为研究样本。黑线姬鼠(Apodemus agrarius)是一种我国常见的农田害鼠,繁殖期短、适应能力强,在我国分布广泛,是影响我国农业生产的主要害鼠之一。另... 自新冠肺炎疫情以来,全球以动物为媒介的传染病不断发生,人们需要更多种类的实验动物作为研究样本。黑线姬鼠(Apodemus agrarius)是一种我国常见的农田害鼠,繁殖期短、适应能力强,在我国分布广泛,是影响我国农业生产的主要害鼠之一。另外,黑线姬鼠也是汉坦病毒(Hantavirus)、莱姆病伯氏疏螺旋体(Borrelia burgdorferi)和刚地弓形虫(Toxoplasma gondii)的天然携带者,是流行病学研究的重要调查样本,同时在构建疾病模型和探究病原体致病机制方面也更具优势,其实验动物化的研究情况应该受到重视。本文总结了黑线姬鼠分类及其分布、繁殖学研究、生理学研究、分子生物学研究、携带病原体概况,并对黑线姬鼠的繁殖研究、多组学应用、病原探究和发展前景进行展望,以期为黑线姬鼠后续实验动物资源开发提供帮助。 展开更多
关键词 黑线姬鼠 实验动物 繁殖 携带病原
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部