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Enhanced Ion Sampling Techniques for In-situ Neutral Gas and Low-energy Ions Exploration of Main-belt Comet
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作者 WANG Xinyue ZHANG Aibing +4 位作者 SU Bin DU Dan KONG Linggao TIAN Zheng ZHENG Xiangzhi 《空间科学学报》 北大核心 2025年第3期749-760,共12页
One of the detection objectives of the Chinese Asteroid Exploration mission is to investigate the space environment near the Main-belt Comet(MBC,Active Asteroid)311P/PANSTARRS.This paper outlines the scientific object... One of the detection objectives of the Chinese Asteroid Exploration mission is to investigate the space environment near the Main-belt Comet(MBC,Active Asteroid)311P/PANSTARRS.This paper outlines the scientific objectives,measurement targets,and measurement requirements for the proposed Gas and Ion Analyzer(GIA).The GIA is designed for in-situ mass spectrometry of neutral gases and low-energy ions,such as hydrogen,carbon,and oxygen,in the vicinity of 311P.Ion sampling techniques are essential for the GIA's Time-of-Flight(TOF)mass analysis capabilities.In this paper,we present an enhanced ion sampling technique through the development of an ion attraction model and an ion source model.The ion attraction model demonstrates that adjusting attraction grid voltage can enhance the detection efficiency of low-energy ions and mitigate the repulsive force of ions during sampling,which is influenced by the satellite's surface positive charging.The ion source model simulates the processes of gas ionization and ion multiplication.Simulation results indicate that the GIA can achieve a lower pressure limit below 10-13Pa and possess a dynamic range exceeding 10~9.These performances ensure the generation of ions with stable and consistent current,which is crucial for high-resolution and broad dynamic range mass spectrometer analysis.Preliminary testing experiments have verified GIA's capability to detect gas compositions such as H2O and N2.In-situ measurements near 311P using GIA are expected to significantly contribute to our understanding of asteroid activity mechanisms,the evolution of the atmospheric and ionized environments of main-belt comets,the interactions with solar wind,and the origin of Earth's water. 展开更多
关键词 neutral gas low energy ions sampling techniques ion sampling techniques investigate space environment main belt comet gas ion analyzer gia situ measurement
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Hydraulic Sliding Formwork Construction Technology for Main Pier Columns of Highway Bridges
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作者 Guangpu Dong Liang Wang 《Journal of World Architecture》 2025年第1期1-6,共6页
Aiming at the problems of difficulty in balancing construction efficiency and quality,as well as the high safety risks of working at heights during the construction of main piers for highway bridges,this study takes a... Aiming at the problems of difficulty in balancing construction efficiency and quality,as well as the high safety risks of working at heights during the construction of main piers for highway bridges,this study takes a specific bridge project as an example to introduce the technology of hydraulically sliding formwork for the construction of main piers of highway bridges.An in-depth analysis of the project’s construction process found that this technology can effectively improve construction efficiency,ensure the quality of concrete pouring,and significantly reduce the potential safety hazards of working at heights.It provides a reliable technical solution for constructing the main piers of highway bridges and has important reference significance for similar projects. 展开更多
关键词 Highway bridges main piers Hydraulic pressure SLIDING FORMWORK
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Cryogenic liquid nitrogen treatment for enhancing gas production in Sui main limestone carbonates, Central Indus Basin, Pakistan
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作者 Muhammad Ali Abdul Majeed Shar +5 位作者 Nurudeen Yekeen Muhammad Furqan Qureshi Muhammad Usman Mohammed Al Kobaisi Muhammad Shahzad Kamal Hussein Hoteit 《Earth Energy Science》 2025年第3期270-281,共12页
The Early Eocene Sui Main Limestone(SML)reservoirs in the Qadirpur area are significant hydrocarbon-producing formations but suffer from low permeability and poor reservoir characteristics that lead to well abandonmen... The Early Eocene Sui Main Limestone(SML)reservoirs in the Qadirpur area are significant hydrocarbon-producing formations but suffer from low permeability and poor reservoir characteristics that lead to well abandonment.Although commonly used,conventional stimulation techniques such as hydraulic fracturing and acidizing pose environmental risks,high costs,and sensitivity to fluctuations in crude oil prices.Meanwhile,cryogenic liquid nitrogen(LN2)treatment has emerged as an innovative,eco-friendly alternative due to its thermal shock effects,which enhance rock permeability and porosity.Herein,SML core samples are treated with LN2 for 30,60,and 90 min to obtain samples designated as SML_30,SML_60,and SML_90,respectively.These are examined using X-ray diffraction(XRD),atomic force microscopy(AFM),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),nanoindentation,and petrophysical measurements to evaluate the changes in their petrophysical,morphological,and micromechanical properties.The post-treatment analysis reveals that LN2 cooling effectively induces micro-cracks,with fracture widths of up to 40μm,along with a substantial increase in surface roughness from 350 to 942 nm.Additionally,micromechanical analysis indicates notable changes in the indentation modulus due to stress-induced alterations in the rock matrix.At optimal LN2 exposure(90 min),the porosity and permeability of the SML sample is more than doubled.These findings provide valuable insights into LN2-induced reservoir enhancements,thereby contributing to a better understanding of fluid flow behavior and hydrocarbon recovery in tight gas reservoirs.Thus,LN2 treatment presents a promising,cost-effective,and environmentally sustainable alternative to conventional stimulation methods. 展开更多
关键词 Sui main limestone Carbonate rocks Cryogenic liquid nitrogen Petrography Pore morphology Petrophysics Central Indus basin
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Modeling evolutionary life history traits of copepods in the Georges Bank and Gulf of Maine region
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作者 Na Li Xianwen Bao +1 位作者 Maochong Shi Meiping Feng 《Acta Oceanologica Sinica》 2025年第8期77-94,共18页
In the paper,copepod universal formulas are applied to construct a copepod individual-based model(IBM),and a genetic algorithm(GA)is incorporated in the formulas with genes as species parameters.The IBM initially cons... In the paper,copepod universal formulas are applied to construct a copepod individual-based model(IBM),and a genetic algorithm(GA)is incorporated in the formulas with genes as species parameters.The IBM initially constructs the individuals with all possible genes similar to the original state of natural selection.Climate-averaged temperature and chlorophyll a(Chl a)time series at the surface layer of fixed points in the Georges Bank(GB)and the Gulf of Maine(GOM)are taken as the model environment.The IBM has been running for 50 a in the environment without inter-annual change.The IBM results indicate that some of the life history traits of the top ten abundant species output by the IBM in the GB and the GOM are consistent with the real species Calanus finmarchicus,Pseudocalanus spp.,Centropages typicus,and Centropages hamatus in terms of reproduction strategy,time to reach the maximum abundance,water temperature preference,and adult body mass.The study of the top ten abundant species with multidimensional scaling(MDS)and clustering analysis(CA)methods indicates that reproduction strategy is the basis for grouping.For the species taking the broadcasting strategy,both GB and GOM environments tend to choose smallbodied species with cold-water preference,such as Pseudocalanus spp.;for the species taking the egg-carrying strategies,the GB environment selects large-bodied species with cold-water preference,such as C.finmarchicus,while the GOM environment selects medium-bodied species with warm-water preference,such as Centropages spp.(C.typicus and C.hamatus).After gene mutation is added to the IBM,the model result gets simple,which needs to be further improved.The significance of the paper lies in systematically studying the impact of GB and GOM environments on the evolutionary life history traits of copepods for the first time. 展开更多
关键词 copepod life history trait individual-based model Georges Bank Gulf of maine
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Research on the Selection and Layout Scheme of Main Transformers in the Primary Electrical Design of New Energy Step-Up Stations
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作者 Yuekai Liao 《Journal of Electronic Research and Application》 2025年第4期254-260,共7页
This paper focuses on the research of the main transformer selection and layout scheme for new energy step-up substations.From the perspective of engineering design,it analyzes the principles of main transformer selec... This paper focuses on the research of the main transformer selection and layout scheme for new energy step-up substations.From the perspective of engineering design,it analyzes the principles of main transformer selection,key parameters,and their matching with the characteristics of new energy.It also explores the layout methods and optimization strategies.Combined with typical case studies,optimization suggestions are proposed for the design of main transformers in new energy step-up substations.The research shows that rational main transformer selection and scientific layout schemes can better adapt to the characteristics of new energy projects while effectively improving land use efficiency and economic viability.This study can provide technical experience support for the design of new energy projects. 展开更多
关键词 New energy step-up substation Engineering design main transformer selection
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Characteristics and Main Points of the Theory and Technology of Hypobaric Storage and Preservation of Fresh Agricultural Products: Insights Gained from Two Monographs by Stanley P. Burg
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作者 Xianzhang ZHENG 《Asian Agricultural Research》 2025年第3期27-39,共13页
In 2004 and 2014,two monographs on hypobaric storage(LP)were published by Stanley P.Burg.Based on his theoretical framework and technological advancements,as well as the research and development of equipment conducted... In 2004 and 2014,two monographs on hypobaric storage(LP)were published by Stanley P.Burg.Based on his theoretical framework and technological advancements,as well as the research and development of equipment conducted under his guidance,alongside customer practices and reflections on various scientific literature both domestically and internationally,it is posited that,as articulated in the monograph,misconceptions regarding his theory and technology in Western scientific literature prior to 1985 continue to persist.This ongoing dissemination of misunderstandings has resulted in a near stagnation of research and has adversely impacted the Chinese academic community as well.Consequently,it is essential to delineate the characteristics and main points of its theory and technology,with the aim of offering guidance to individuals seeking to comprehend its foundational purpose.LP technology is a dynamic physical technology that continuously and uninterruptedly extracts air from a closed container and simultaneously introduces fresh,low-pressure moist air from the external environment,while maintaining specific levels of humidity and/or temperature within the container and upholding a predetermined pressure value.Preservation technology is the collective term for the set of various technical parameters associated with preservation,including pressure,relative humidity,and other relevant factors,to which LP equipment is specifically designed.The theory of LP is characterized by the enhanced diffusion of gases and vapors that enter and exit the commodity in a dynamic manner under low pressure conditions.The theoretical points involve equipment performance,low pressure,the impact of trace concentrations of gases such as O_(2),CO_(2) and C_(2)H_(4) that naturally occur at low pressure,diffusive mass transfer,heat transfer,and impacts on the activity of enzymes associated with maturation and senescence.The technology is characterized by dynamic low pressure,and the range of commodities preserved is comparable to that of refrigeration.However,certain commodities exiting the hypobaric environment possess subsequent preservation advantages that are not available through refrigeration.The main points of the technology encompass an extended sotrage life,a postponement of quality degradation,minimized water loss,the suppression of pathogen growth,and the killing of both internal and external insects of the commodity under dynamic low pressure conditions.The core advantage of LP technology lies in its ability to significantly reduce water loss,inhibit respiration and C_(2)H_(4) action,and pathogen growth,killing insects and modulate the activity of enzymes associated with maturation and senescence in post-harvest fresh horticultural products.Consequently,this technology plays a crucial role in prolonging the post-harvest lifespan of these commodities and mitigating quality degradation.Over the past decade,researchers in China have developed a hypobaric short period treatment technology,grounded in LP theory and technical practice,which is commonly referred to as hypobaric treatment.This method has garnered significant attention,leading to an increase in both domestic and international research.A growing body of literature categorizes LP as hypobaric treatment,while some studies also consider vacuum packaging and modified atmosphere packaging(MAP)as LP or hypobaric treatment.Misunderstandings are exacerbated by confusion surrounding nomenclature,which,in conjunction with pre-existing misconceptions,represents a significant barrier to both the research and practical application of the technology.The successful commercial implementation of a vacuum cold fresh chain,centered on LP or hypobaric treatment technology,may be the sole solution to the prevailing misunderstandings associated with LP. 展开更多
关键词 Hypobaric storage Stanley P.Burg Hypobaric treatment preservation THEORY Technology Characteristics and main points Vacuum cold fresh chain
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Main factors controlling unconventional gas enrichment and high production in the first member of Permian Maokou Formation,southeastern Sichuan Basin,SW China
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作者 HE Guisong SUN Bin +4 位作者 GAO Yuqiao ZHANG Peixian ZHANG Zhiping CAI Xiao XIA Wei 《Petroleum Exploration and Development》 2025年第2期408-421,共14页
Based on the data of drilling,logging,experiment and gas testing in the Nanchuan area,southeastern Sichuan Basin,the hydrocarbon generation potential,gas genesis,occurrence state,migration,preservation conditions,pore... Based on the data of drilling,logging,experiment and gas testing in the Nanchuan area,southeastern Sichuan Basin,the hydrocarbon generation potential,gas genesis,occurrence state,migration,preservation conditions,pore and fracture features and accumulation evolution of the first member of Permian Maokou Formation(Mao 1 Member)are systematically studied,and the main controlling factors of unconventional gas enrichment and high production in marlstone assemblage of Mao 1 Member are discussed.(1)The enrichment and high yield of unconventional natural gas in the Mao 1 Member are controlled by three factors:carbon-rich fabric controlling hydrocarbon generation potential,good preservation controlling enrichment,and natural fracture controlling production.(2)The carbonate rocks of Mao 1 Member with carbon rich fabric have significant gas potential,exhibiting characteristics of self-generation and self-storage,which lays the material foundation for natural gas accumulation.(3)The occurrence state of natural gas is mainly free gas,which is prone to lateral migration,and good storage conditions are the key to natural gas enrichment.Positive structure is more conducive to natural gas accumulation,and a good compartment is created jointly by the self-sealing property of the Mao 1 Member and its top and bottom sealing property in monoclinal area,which is favorable for gas accumulation by retention.(4)Natural fractures are the main reservoir space and flow channel,and the more developed natural fractures are,the more conducive to the formation of high-quality porous-fractured reservoirs and the accumulation of natural gas,which is the core of controlling production.(5)The accumulation model of unconventional natural gas is proposed as“self-generation and self-storage,preservation controlling richness,and fractures controlling production”.(6)Identifying fracture development areas with good preservation conditions is the key to successful exploration,and implementing horizontal well staged acidizing and fracturing is an important means to increase production and efficiency.The study results are of referential significance for further understanding the natural gas enrichment in the Mao 1 Member and guiding the efficient exploration and development of new types of unconventional natural gas. 展开更多
关键词 Sichuan Basin PERMIAN Maokou Formation unconventional natural gas main controlling factors of enrichment and high production accumulation model carbonate rock southeastern Sichuan Basin
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南美奥连特盆地白垩系Napo组Main-M1亚段沉积体系重建及油气勘探意义 被引量:4
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作者 李发有 班舒悦 +9 位作者 王光付 孙建芳 丁峰 孙钰 王腾宇 徐海 陈诗望 夏昌盛 郑乃熙 鲍志东 《古地理学报》 CAS CSCD 北大核心 2024年第1期17-27,共11页
厄瓜多尔奥连特盆地是南美安第斯前陆盆地群中最重要的含油气盆地之一,上白垩统Napo组Main-M1亚段是目前勘探开发的主力层位之一,其沉积环境一直存在争议,沉积体系及演化过程尚不明确。本研究基于岩心、测录井等资料,针对Main-M1亚段沉... 厄瓜多尔奥连特盆地是南美安第斯前陆盆地群中最重要的含油气盆地之一,上白垩统Napo组Main-M1亚段是目前勘探开发的主力层位之一,其沉积环境一直存在争议,沉积体系及演化过程尚不明确。本研究基于岩心、测录井等资料,针对Main-M1亚段沉积时期的主要沉积微相类型、沉积体系及演化过程进行了研究。结果表明:研究区位于水动力条件复杂的海陆过渡环境,在东部发育潮汐三角洲,向西部逐渐过渡为浅海陆棚环境;研究区内主要识别出水下分流河道、水下分流河道间、潮汐水道、潮汐沙坝、潮汐沙坪、潮汐水道间等8类沉积微相。根据岩电特征,进一步将Main-M1亚段划分为3个小层。通过分析3个小层的岩性组合演变特征,确定在Main-M1亚段沉积时间内,Auca古隆起逐渐形成,同时挠曲作用导致相对海平面升高,3个小层在垂向上呈水体逐渐变深、潮汐三角洲前缘不断向陆地退缩的形式;基于对Main-M1亚段沉积时期潮汐三角洲—浅海陆棚沉积体系的重建,研究区东部的水下分流河道及前缘沙坝也被认为具有一定的岩性油气藏勘探潜力。 展开更多
关键词 潮汐三角洲 陆棚 沉积微相 沉积模式 main-M1亚段 奥连特盆地 南美洲
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南美奥连特盆地坎潘阶碳酸盐岩建隆的识别及科迪勒拉运动早期抬升对Main-M1储集层沉积的控制作用 被引量:1
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作者 丁峰 王光付 +6 位作者 孙建芳 孙钰 李发有 薛明喜 吴洁 班舒悦 鲍志东 《古地理学报》 CAS CSCD 北大核心 2024年第1期5-16,共12页
厄瓜多尔奥连特盆地Main-M1砂岩储集层是该盆地近年来重要的构造-岩性圈闭勘探目的层系,寻找砂体和岩性尖灭带是Main-M1砂岩勘探的关键。该盆地为晚白垩世弧后热沉降盆地和新生代前陆盆地的叠合盆地,在构造上分为西部逆冲褶皱带、中部... 厄瓜多尔奥连特盆地Main-M1砂岩储集层是该盆地近年来重要的构造-岩性圈闭勘探目的层系,寻找砂体和岩性尖灭带是Main-M1砂岩勘探的关键。该盆地为晚白垩世弧后热沉降盆地和新生代前陆盆地的叠合盆地,在构造上分为西部逆冲褶皱带、中部前渊带和东部斜坡带,在前渊带发育一系列近N-S走向长轴背斜。综合观察和分析发现,在研究区内长轴背斜上生长了1个碳酸盐岩建隆,地震上具有明显的边界反射形成丘状外观和较连续的弱振幅内部反射,测井上具有厚层、近箱型低GR响应特征。该建隆表明在其沉积的坎潘阶时期,长轴背斜已经开始抬升,将背斜顶部推升至古水面附近,形成建隆局部生长的条件。压实回剥方法恢复古地貌证实,长轴背斜在坎潘阶早期开始发育,构造抬升幅度为7~10 m。由于构造抬升和建隆发育始于Main-M1沉积前,抬升古地貌可影响砂岩沉积。根据背斜上数十口已钻井Main-M1砂体厚度统计,发现背斜顶部砂岩储集层整体较发育,但古建隆顶部砂层厚度减薄或者缺失,在背斜的南部延伸段,构造顶部砂岩缺失,仅在东部侧翼富集。提出了近N-S向背斜古地貌影响Main-M1砂体沉积,使砂岩于富集于构造下倾方向的控砂模式。该模式可形成上倾尖灭型构造-岩性圈闭,从而提供了通过古地貌恢复在奥连特盆地前渊带寻找新圈闭的勘探思路。 展开更多
关键词 奥连特盆地 科迪勒拉运动 碳酸盐岩建隆 古地貌 main-M1储集层 构造-岩性圈闭
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Fractal Characteristics and Main Controlling Factors of High-Quality Tight Sandstone Reservoirs in the Southeastern Ordos Basin 被引量:1
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作者 Ruilin Hao Wenhui Huang +1 位作者 Jiu Bo Li Yuan 《Journal of Earth Science》 SCIE CAS CSCD 2024年第2期631-641,共11页
Due to the complex conditions and strong heterogeneity of tight sandstone reservoirs,the reservoirs should be classified and the controlling factors of physical properties should be studied.Cast thin section observati... Due to the complex conditions and strong heterogeneity of tight sandstone reservoirs,the reservoirs should be classified and the controlling factors of physical properties should be studied.Cast thin section observations,cathodoluminescence,scanning electron microscopy(SEM),X-ray diffraction(XRD),and high-pressure mercury injection(HPMI)were used to classify and optimize the reservoir.The Brooks-Corey model and stepwise regression were used to study the fractal dimension and main controlling factors of the physical properties of the high-quality reservoir.The results show that the reservoirs in the study area can be divided into four types,and the high-quality reservoir has the best physical properties and pore-throat characteristics.In the high-quality reservoir,the homogeneity of transitional pores was the best,followed by that of micropores,and the worst was mesopores.The porosity was controlled by depth and kaolinite.The model with standardized coefficients is y=12.454−0.778×(Depth)+0.395×(Kaolinite).The permeability was controlled by depth,illite/montmorillonite,and siliceous cement,and the model with standardized coefficients is y=1.689−0.683×(Depth)−0.395×(Illite/Montmorillonite)−0.337×(Siliceous Cement).The pore-throat evolutionary model shows that the early-middle diagenetic period was when the reservoir physical properties were at their best,and the kaolinite intercrystalline pores and residual intergranular pores were the most important. 展开更多
关键词 fractal dimension main controlling factors stepwise regression high-quality tight sandstone reservoir Ordos Basin petroleum geolgoy
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Ground response and failure mechanism of gob-side entry by roof cutting with hard main roof 被引量:1
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作者 ZHU Heng-zhong XU Lei WEN Zhi-jie 《Journal of Central South University》 SCIE EI CAS CSCD 2024年第7期2488-2512,共25页
This study is the result of long-term efforts of the authors’team to assess ground response of gob-side entry by roof cutting(GSERC)with hard main roof,aiming at scientific control for GSERC deformation.A comprehensi... This study is the result of long-term efforts of the authors’team to assess ground response of gob-side entry by roof cutting(GSERC)with hard main roof,aiming at scientific control for GSERC deformation.A comprehensive field measurement program was conducted to determine entry deformation,roof fracture zone,and anchor bolt(cable)loading.The results indicate that GSERC deformation presents asymmetric characteristics.The maximum convergence near roof cutting side is 458 mm during the primary use process and 1120 mm during the secondary reuse process.The entry deformation is closely associated with the primary development stage,primary use stage,and secondary reuse stage.The key block movement of roof cutting structure,a complex stress environment,and a mismatch in the supporting design scheme are the failure mechanism of GSERC.A controlling ideology for mining states,including regional and stage divisions,was proposed.Both dynamic and permanent support schemes have been implemented in the field.Engineering practice results indicate that the new support scheme can efficiently ensure long-term entry safety and could be a reliable approach for other engineering practices. 展开更多
关键词 gob-side entry by roof cutting ground response failure mechanism following mining states control hard main roof
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Strong shock propagation for the finite-source circular blast in a confined domain
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作者 Qihang MA Kaileong CHONG +1 位作者 Bofu WANG Quan ZHOU 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2024年第6期1071-1084,共14页
The circular explosion wave produced by the abrupt discharge of gas from a high-temperature heat source serves as a crucial model for addressing explosion phenomena in compressible flow.The reflection of the primary s... The circular explosion wave produced by the abrupt discharge of gas from a high-temperature heat source serves as a crucial model for addressing explosion phenomena in compressible flow.The reflection of the primary shock and its propagation within a confined domain are studied both theoretically and numerically in this research.Under the assumption of strong shock,the scaling law governing propagation of the main shock is proposed.The dimensionless frequency of reflected shock propagation is associated with the confined distance.The numerical simulation for the circular explosion problem in a confined domain is performed for validation.Under the influence of confinement,the principal shock wave systematically undergoes reflection within the domain until it weakens,leading to the non-monotonic attenuation of kinetic energy in the explosion fireball and periodic oscillations of the fireball volume with a certain frequency.The simulation results indicate that the frequency of kinetic energy attenuation and the volume oscillation of the explosive fireball align consistently with the scaling law. 展开更多
关键词 explosion CONFINEMENT main shock frequency
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Analysis of Dry-Wet Climate Change Characteristics and Main Influencing Factors in Main Grain Producing Area of Xizang from 1980 to 2021
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作者 Sangbu ZHUJIE Cunjie ZHANG +3 位作者 Puchi ZHAXI Deji BAIMA Lamu NIMA Ciwang PINGCUO 《Agricultural Biotechnology》 2024年第2期43-49,63,共8页
Based on the daily meteorological observation data of seven meteorological stations in southern Xizang from 1980 to 2021(April-October),the temporal and spatial variation characteristics and influencing factors of ari... Based on the daily meteorological observation data of seven meteorological stations in southern Xizang from 1980 to 2021(April-October),the temporal and spatial variation characteristics and influencing factors of aridity index(AI)in the growing season of major grain producing areas in Xizang were studied by using climate tendency rate,Mann-Kendal test,Morlet wavelet analysis,GIS hybrid interpolation method,Pearson correlation coefficient,contribution rate analysis and other methods.The results showed that the average AI in the main grain producing areas of Xizang was 1.7,which belonged to the semi-arid area,and the overall trend was decreasing(humidifying)(-0.036/10 a).The linear decreasing trend was different in different regions,and the area around Lhatse County was the most significant(-0.26/10 a).AI had no obvious abrupt change,and had long-and medium-term fluctuation characteristics of 24 years,6 years.The spatial distribution was uneven,and had the characteristics of‘shrinking arid area and expanding humid area.The contribution rates of the main climate influencing factors of AI varied in different regions.In general,the contribution rates after quantification was as follows:precipitation(34.9%)>relative humidity(28.4%)>sunshine(19.9%)>maximum temperature(12.4%). 展开更多
关键词 Xizang main production area CLIMATE ARIDITY Contribution rate
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Acute Left Main Coronary Occlusion Following Transcatheter Aortic Valve Implantation
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作者 Alekhya Abburu Basharat Ahmad +2 位作者 Abdallah Masri David Nery Sharon Rufus 《World Journal of Cardiovascular Diseases》 CAS 2024年第11期695-700,共6页
Background: Aortic stenosis (AS) is caused by either age-related degeneration of aortic valve or congenital malformation of aortic cusps. Severe aortic valve stenosis is a clinically emerging diagnosis in the current ... Background: Aortic stenosis (AS) is caused by either age-related degeneration of aortic valve or congenital malformation of aortic cusps. Severe aortic valve stenosis is a clinically emerging diagnosis in the current world. The three cardinal signs of severe AS are dyspnea, syncope, and angina. Transcatheter aortic valve implantation is one of the safe and effective methods for treating severe aortic valve stenosis, and an alternative to surgery in high-risk patients. Aortic valve calcification and changes after TAVI were specifically assessed by computed tomography. Excessive aortic valve calcification is related to procedural complications. A possible consequence is obstruction of coronary ostia. Heavy calcification of the aortic valve and surrounding structure is an important risk factor for coronary obstruction, heart block, and embolization during aortic valve implantation (TAVI). Here we present a case of an elderly old man, where critical ostial left main coronary artery (LMCA) disease was caused by shifting of a calcium speck rather than obstruction with native leaflet. He was successfully rescued by an emergent CABG. Methods and Results: This is a case of a 69-year-old man with severe calcific aortic stenosis and single-vessel CAD who underwent TAVI with a relatively unremarkable course. Notably, his pre-operative TAVI angiography showed no LMCA stenosis. But 10 days later he presented to the ER with acute myocardial infarction with peak high-intensity troponins, diffuse ST changes, and cardiogenic shock. Urgent coronary angiography and intravascular ultrasound showed critical LMCA stenosis caused by a speck of calcium externally abating the vessel. He underwent emergency coronary artery bypass grafting;intraoperative TEE confirmed the etiology. He had an uneventful postoperative course and was successfully weaned off vasoactive medications. Conclusion: This case illustrates that obstruction of coronary ostia could be a possible complication of TAVI. Calcium distribution should factor in TAVI versus surgical candidacy. Calcium shifting should be watched closely during valve deployment, post-TAVI coronary angiogram should be considered if shifting was significant or suspected to compromise coronary arteries. 展开更多
关键词 TAVI (Transcatheter Aortic Valve Implantation) LMCA (Left main Coronary Artery) CAD (Coronary Artery Disease) TEE (Transoesophageal Echocardiography) Intravascular Ultrasound Severe Calcific Aortic Stenosis CABG (Coronary Artery Bypass Grafting)
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Minimally Invasive Total Arterial Coronary Artery Bypass Grafting in Left Main Stem Disease
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作者 Pradeep Nambiar Radwan Husseini Prashant Sagar 《World Journal of Cardiovascular Surgery》 2024年第7期107-114,共8页
Objective: The aim was to show that Minimally Invasive total arterial revascularization for left main stem coronary artery disease, via a left anterior Mini thoracotomy using bilateral internal thoracic arteries is fe... Objective: The aim was to show that Minimally Invasive total arterial revascularization for left main stem coronary artery disease, via a left anterior Mini thoracotomy using bilateral internal thoracic arteries is feasible, reproducible and safe. Further, there has been no exclusive data or experience with minimally invasive coronary artery bypass grafting in left main stem disease. Methods: From April 2019 to March 2024, 41 patients with left main stem stenosis, left main equivalent disease and unprotected left main with triple vessel disease underwent off pump minimally invasive multivessel coronary artery bypass grafting using either in situ pedicled Bilateral Internal Thoracic arteries or Left and Right Internal Thoracic artery Y composite conduits at three centers. Bilateral Internal Thoracic arteries were harvested under direct vision. All patients had an Intra-Aortic Balloon Pump inserted via the femoral artery prior to induction of anesthesia, to prevent any hemodynamic instability, arrhythmias, and was removed following completion of the procedure in the operating room without any complications. Efficacy and outcomes were evaluated by i) Primary (MACCE)-Major Adverse Cardiac and Cardiovascular events and ii) Secondary outcome measures including total length of stay, return to full physical activity and quality of life. Mean follow-up was 1.4 years (Maximum was 2.5 years). Results: 41 patients with left main stem coronary artery stenosis, underwent total arterial revascularization using bilateral internal thoracic arteries. Left main stem stenosis was present in 29 patients, Unprotected left main stem stenosis with triple vessel disease in 7 and left main equivalence in 5 patients. In this cohort, 29 patients with only left main stem stenosis had 2 grafts each, 7 patients with left main and triple vessel disease had 3 grafts and 5 patients with left main equivalent disease had 2 grafts respectively. The average number of grafts was 2.2. One patient was converted to open sternotomy as an emergency because of hemodynamic instability and myocardial revascularization was done on cardiopulmonary bypass (2.2%). The average hospital stay was 3.7 days. Ejection fraction was 45% ± 5%. There was one mortality (2.2%) but no major morbidity. The average ICU and hospital stay was 24 ± 4 hours and 3.7 days. All patients were free from major adverse cardiac and cerebrovascular events at follow-up. Conclusions: Multivessel total arterial revascularization using left and right internal thoracic arteries, was performed via a left anterior Mini thoracotomy on patients with left main stem disease and showed that it was safe, reproducible and will help extend the armamentarium of the surgeon in minimally invasive Coronary artery bypass grafting. Concomitantly it helped enhance the potential for shorter hospital stay, increased survival, decreased morbidity, and earlier return to full activity. Furthermore, the safety, efficacy, and outcomes of minimally invasive coronary artery bypass grafting in this high-risk group evaluated by primary and secondary outcome measures have been good in this study. 展开更多
关键词 Left main Stem Minimally Invasive CABG Bilateral Internal Mammary Arteries
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Analyses of the characteristics and main controlling factors of shale pores in the Niutitang Formation in the Guizhou region
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作者 Daquan Zhang Yi Chen +6 位作者 Shengyuan Ji Qingbo He Yisong Wang Ruiqin Lin Fulun Shi Xia Feng Wei Du 《Natural Gas Industry B》 2024年第4期394-404,共11页
The shale of the Lower Cambrian Niutitang Formation in the Guizhou region has undergone complex diagenesis and has developed different types of pore textures,which affect the occurrence status of shale.In the present ... The shale of the Lower Cambrian Niutitang Formation in the Guizhou region has undergone complex diagenesis and has developed different types of pore textures,which affect the occurrence status of shale.In the present study,we applied scanning electron microscopy(SEM)and an isotherm analysis of low-temperature nitrogen gas adsorption to shale core samples drawn from the Niutitang Formation in the Guizhou region to quantify the shale pore development characteristics.In addition,we conducted a shale geochemical analysis in light of the main controlling factors for pore development.The results indicate that the shale pores and fractures of the Niutitang Formation can be divided into three types:organic pores,inorganic pores,and micro fractures.The organic pores are mainly distributed in the organic matter between inorganic mineral particles,with small pore diameters,which are characterized by inkpot,elliptic,and beaded shapes.The inorganic pores are mainly composed of narrow slit intragranular pores and intergranular pores.The micro fractures develop parallel plates with four-side openings and splint plates.The pores of the shale are mainly mesopores(53%),followed by micropores and macropores,with pore diameter distributions ranging mainly from 1 to 50 nm.The specific surface area is mainly provided by nanoscale pores with average diameters of less than 4 nm.Therefore,the smaller pore makes a greater contribution to the specific surface area,while the specific surface area increases with an increase in the total pore volume.The study further indicates that organic carbon content is the most important internal factor for shale pore development,especially in terms of the control of volume and the specific surface area of micropores.Moreover,quartz content has a certain effect on shale pores;the pore volume and specific surface area increase with increasing quartz content,but the control effect is not obvious.The effect of clay minerals on shale pores is negligible.The type of organic matter is also an important factor in controlling the developmental difference of shale pores,and a high degree of thermal evolution is not conducive to organic pore development.It was therefore concluded that intergranular pores and microfractures,mainly mesopores,are the main reservoir space and migration channels of Niutitang shale in the study area.The organic carbon content,mineral components,organic matter type,and degree of thermal evolution jointly control the development of shale pores,among which the organic carbon content is the most important influencing factor. 展开更多
关键词 Guizhou region Niutitang formation Shale pore Development characteristics main controlling factor
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“Eternal Motion” as a “Form of Movement of a Special Nature” and the Main Condition for the Creation of the Universe
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作者 Avas Khugaev Eugeniya Bibaeva 《Journal of Applied Mathematics and Physics》 2024年第6期2041-2068,共28页
The article hypothesizes that DE and DM (UCM) are a “Form of Motion of a Special Nature”, where “Form of Motion” means “Eternal Motion” as the power of dynamics of different levels and varying degrees of self-su... The article hypothesizes that DE and DM (UCM) are a “Form of Motion of a Special Nature”, where “Form of Motion” means “Eternal Motion” as the power of dynamics of different levels and varying degrees of self-sufficiency, and by “Special Nature”, gravitational and two other properties of matter, “tied” to the “Eternal Movement” and completely dependent on it. Carriers of key properties of a “Special Nature” have been established: “0”-DE particles and “3”-DM particles (UDM). The unity of their inherent “motionally-gravitational” properties and the peculiarity of the relationship between “motion” and “gravity” are revealed: the higher the intensity of “Eternal Motion”, the stronger the gravitational properties of matter are manifested (and vice versa). The relationship of “time” with the “vibration frequency” and the “mass” of photons with the “degree of bonding and deformation properties of the field” is shown. The maximum level of gravity has been determined, which allows Nature to successfully create the Universe: such a landmark is the proximity to the property of the Primary Source—the “pure graviton” of the OSP space, the most powerful “motionally-gravitational” particle of the Universe. The reasons for the emergence of such an identity of the gravitational properties of particles with the indicators of a “pure graviton” are established: for “0”-DE particles, this is the acquisition of the function of “freedom of movement”;for “3”-DM particles (UDM), the creation of a special structure—a “double field” (“Main” and “Small”). The presence in the “double field” of specific “tools” for the creation of the worlds of the Universe—gravitational “waves” gives rise to impulses (shocks) of varying intensity and shape. A list of functions performed by “waves” in the “Main” and “Small” fields has been compiled. The specific conditions for the formation of “UDM Streams”, their transformation into a “Vortex” and, under the influence of a powerful Initial Impulse (push), sending them to the “place” of the creation of galaxies, are shown. It is suggested that there is a “Cycle of Matter in Nature” in the closed structure of our Universe due to the “work” of “waves” and the functioning of special “factories” in the form of exotic space objects—Black holes. 展开更多
关键词 DE DM (UCM) Graviton Eternal motion Double Field of the Universe Motionally-Gravitational Particles Degree of Self-Sufficiency main Field Small Field Gravitational Waves Primary Impulse Flows UDM Vortex Time Massive Photons Clumps of DM Movement of Galaxies Factories of Black Holes Circulation of Matter in Nature
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Study on the Countermeasures to Improve the Public Outdoor Leisure and Fitness Function on the Two Rivers and Four Banks in the Main Urban Area of Chongqing
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作者 Yuan Li Dexin Li 《Journal of Architectural Research and Development》 2024年第6期51-57,共7页
The main urban area of Chongqing is surrounded by two rivers and set against each other.With its unique waterfront landscape,it has the resource conditions to become a leisure tourism destination.Intending to enhance ... The main urban area of Chongqing is surrounded by two rivers and set against each other.With its unique waterfront landscape,it has the resource conditions to become a leisure tourism destination.Intending to enhance people’s happiness,improve city quality,and promote Chongqing’s main urban area to become a tourist destination,this paper finds out the existing problems in the construction of public outdoor leisure and fitness facilities on the two rivers and four banks of Chongqing’s main urban area through investigation and analysis based on relevant experiences at home and abroad,takes the value chain theory as the guidance,and to find solutions to the problem.On this basis,combined with the law of economic operation,this paper puts forward the guiding ideology,principles,development goals,functional orientation,and development path for the improvement of public outdoor leisure and fitness on two rivers and four banks in the main city of Chongqing,and accordingly puts forward the policy system and guarantee measures for its improvement. 展开更多
关键词 Two rivers and four banks in the main city of Chongqing Public outdoor recreation and fitness Policy measure
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基于MAIN模型的社会化媒体信息可信度影响因素研究——以微信公众号为例 被引量:12
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作者 樊茗玥 王若楠 +1 位作者 覃睿 刘凌燕 《情报科学》 CSSCI 北大核心 2017年第7期101-106,共6页
【目的/意义】在信息时代,用户对社会化媒体的信任程度显得尤为重要。针对目前社会化媒体信息内容可信度低的问题,提出了社会化媒体信息可信度的影响因素,以期为社会化媒体用户、平台及信息监管部门的相关行为提供参考依据。【方法/过... 【目的/意义】在信息时代,用户对社会化媒体的信任程度显得尤为重要。针对目前社会化媒体信息内容可信度低的问题,提出了社会化媒体信息可信度的影响因素,以期为社会化媒体用户、平台及信息监管部门的相关行为提供参考依据。【方法/过程】结合具有心理学特征的MAIN模型,提出社会化媒体信息可信度体系,并借助实证数据,从信息内容角度对社会化媒体信息可信度的影响因素进行了深入研究。【结果/结论】研究表明,信息内容的实用性、客观性、可靠性和相关性对社会化媒体信息可信度会产生积极影响,但是信息内容的一致性则不会产生直接影响。 展开更多
关键词 社会化媒体 信息可信度 main模型 影响因素
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Construction of Anti-breaking Models of the Main Veins of Flue-cured Tobacco Leaves and Principal Component Analysis 被引量:4
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作者 王宝玉 孙婷婷 +3 位作者 章国顺 张蜀香 阮龙 张云华 《Agricultural Science & Technology》 CAS 2011年第11期1615-1616,1656,共3页
[Objective] This study aimed to explore the related mechanisms of the breaking of flue-cured tobacco leaves. [Method] Anti-breaking models of the main veins of flue-cured tobacco leaves were constructed for principal ... [Objective] This study aimed to explore the related mechanisms of the breaking of flue-cured tobacco leaves. [Method] Anti-breaking models of the main veins of flue-cured tobacco leaves were constructed for principal component analysis on the anti-breaking index, leaf traits and cellulose contents. [Result] The results showed that the growth traits had certain relevance with the cellulose contents while the leaf weight assumed a significant negative correlation with the anti-breaking index, indicating that the heavier the leaf weight was, the weaker the anti-breaking capacity of flue-cured tobacco would be; the cross-sectional area of main veins and the cellulose contents had shown a positive correlation with the anti-breaking index, indicating that the thicker the main vein of flue-cured tobacco was, the higher the cellulose contents would be, and the stronger the anti-breaking capacity of flue-cured tobacco leaves would be. [Conclusion] This study provided theoretical basis and reference to improve tobacco production and enhance the quality of flue-cured tobacco. 展开更多
关键词 Flue-cured tobacco main vein Anti-breaking index Principal component analysis
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