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An Empirical Study on Chinese City Network Pattern Based on Producer Services

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Chinese Geographical Science 2013年第3期23卷 274-285页

作者： ZHEN Feng WANG Xia YIN Jun ZHANG Min school of Architecture and Urban Planning Nanjing University Center of Human geography Research Nanjing University school of geography and Ocean sciences Nanjing University

Globalization and informatization have accelerated city networking process over the world, which makes research on city network a hot topic in the fields of urban geography and economic geography. With Chinese economic structure adjustment and city economic growth, producer services have begun to play an increasingly important role in city-region networking. This paper employs the methodology of world city network to analyze and explain the spatial development characteristics of China's urban network system based on the data of nationwide producer services enterprise network. The research result indicated that the distribution of producer services network has a positive effect on the development of Chinese city networks. City network connectivity is closely related to the significance of city in producer services development, and the former will gradually decline with the drop of the latter. Accordingly, the 64 cities can be divided into the national central cities, regional central cities, sub-regional central cities and local central cities in accordance with their position and role in the nationwide producer services network. It is concluded that high-grade cities with quality producer services dominate the pattern of Chinese city networks and there emerges three spatial agglomerations of producer services enterprises in Changjiang (Yangtze) River Delta, Zhujiang (Pearl) River Delta and Beijing-Tianjin-Tangshan Economical Region. Moreover, the distribution of different producer services industry varies from city to city, which also affects the characteristics of network development.

关键词： world city network producer services urban hierarchy network connectivity Chinese city network

The transport of water in subduction zones

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Science China earth sciences 2016年第4期59卷 651-682页

作者： ZHENG YongFei CHEN RenXu XU Zheng ZHANG ShaoBing school of earth and Space sciences University of Science and Technology of China

The transport of water from subducting crust into the mantle is mainly dictated by the stability of hydrous minerals in subduction zones. The thermal structure of subduction zones is a key to dehydration of the subducting crust at different depths. Oceanic subduction zones show a large variation in the geotherm, but seismicity and arc volcanism are only prominent in cold subduction zones where geothermal gradients are low. In contrast, continental subduction zones have low geothermal gradients, resulting in metamorphism in cold subduction zones and the absence of arc volcanism during subduction. In very cold subduction zone where the geothermal gradient is very low(?5?C/km), lawsonite may carry water into great depths of ?300 km. In the hot subduction zone where the geothermal gradient is high(>25?C/km), the subducting crust dehydrates significantly at shallow depths and may partially melt at depths of <80 km to form felsic melts, into which water is highly dissolved. In this case, only a minor amount of water can be transported into great depths. A number of intermediate modes are present between these two end-member dehydration modes, making subduction-zone dehydration various. Low-T/low-P hydrous minerals are not stable in warm subduction zones with increasing subduction depths and thus break down at forearc depths of ?60–80 km to release large amounts of water. In contrast, the low-T/low-P hydrous minerals are replaced by low-T/high-P hydrous minerals in cold subduction zones with increasing subduction depths, allowing the water to be transported to subarc depths of 80–160 km. In either case, dehydration reactions not only trigger seismicity in the subducting crust but also cause hydration of the mantle wedge. Nevertheless, there are still minor amounts of water to be transported by ultrahigh-pressure hydrous minerals and nominally anhydrous minerals into the deeper mantle. The mantle wedge overlying the subducting slab does not partially melt upon water influx

关键词： Subduction zones Oceanic crust Mantle wedge Thermal structure Hydrous minerals Water transport Arc magmatism

Septal patterns in Agetolites from the Xiazhen Formation(Upper Ordovician) at Zhuzhai,Yushan County,Jiangxi Province,South China

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Science China earth sciences 2014年第2期57卷 247-257页

作者： SUN Ning DongJin LEE WANG XunLian school of earth sciences and Resources China University of Geosciences Department of earth and Environmental sciences Andong National University College of earth sciences Jilin University

Patterns of septal insertion were analyzed in three species of Agetolites from the Upper Ordovician in Yushan County, Jiangxi Province of China. Agetolites is a peculiar coral possessing features of both tabulate （e.g., mural pores） and rugose corals （e.g., welldeveloped septa）. Septal patterns have long been considered to be indicative of the origin of corals, and the pattern of septal insertion in Agetolites has been known to be typical of rugosans. This study, however, reveals that the patterns in Ageto lites are rather random and cannot be an indication of its rugosan affinity. It is suggested that Agetolites probably has a closer phylogenetic relation with tabulates than with either rugosans or scleractinians. Two insertion patterns of the first six septa were detected （Types I and II）. Type I is interpreted as scleractinian pattern whereas Type II as typical pattern of rugosans. Types 1 and 2 are septal patterns of the second stage recognized in this study. Type 1 insertion occurs in six sectors located in the center of each interseptal space, suggesting scleractinian pattern of insertion. Type 2 insertion occurs in four sectors that are comparable with alar and counter sectors in rugose corals. Four patterns of the third （Types AD） and fourth stages （Types ad） of septal insertion have also been recognized in Agetolites. Type A only occurs in two adjacent sectors possibly due to the in completeness of septal development. Type B presents rugosan pattern. Types C and D resemble scleractinian pattern in most aspects. Types a, b, and c present no clear attribution to rugosan or scleractinian pattern probably due to the incompleteness of septal development whereas Type d is observable in rugose corals.

关键词： Agetolites septal patterns Tabulata Upper Ordovician

Application of Detrital Apatite U-Pb Geochronology and Trace Elements for Provenance Analysis,Insights from a Study on the Yarlung River Sand

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Journal of earth Science 2024年第4期35卷 1118-1129页

作者： Yufeng Du Guangwei Li Danyang Liu Xianyan Wang Dongxu Cai Xiaolu Dong Qi Yu State Key Laboratory for Mineral Deposits Research School of Earth Sciences and EngineeringNanjing UniversityNanjing210023China school of geography and Ocean Nanjing UniversityNanjing210023China

Detrital U-bearing minerals(e.g.,zircon,apatite)U-Pb ages with specific trace-element geochemistry,are frequently used in provenance *** this study,we focus on the Yarlung River drainage in South Tibet,characterized by two distinct lithologic units:The Gangdese batholith to the north(mainly granitoids)and the Tethyan Himalaya(mainly sedimentary rocks)to the south,which plays a crucial role in the erosion of the Tibetan *** constrain the provenance of the Yarlung River Basin,we performed trace-element and U-Pb age analyses of detrital apatite from the river sands of the Yarlung River and its *** findings indicate that the detrital apatite U-Pb age patterns of the north tributaries exhibit main peaks at approximately 40 and 60 Ma,consistent with the corresponding U-Pb age patterns of detrital zircon ***,their trace element casts fall mainly in the Type I granite region,also indicating the Gangdese arc-dominated ***,those of the south tributaries(∼60–20 Ma)exhibit a different age distribution from the detrital zircon U-Pb groups(∼110–150,∼500,and 1100 Ma),suggesting that the detailed apatite U-Pb signals can provide excellent constraints on the provenance of igneous and metamorphic rock sources but less so for sedimentary rock *** with previous detrital zircon data in the study area,our detrital apatite information can highlight young metamorphic events from a complex background(i.e.,Niyang and Nianchu rivers),which offers additional constraints on the provenance of the Yarlung River ***,a combination of geochemistry and geochronology of multi-detrital heavy minerals,such as zircon and apatite,can provide powerful tools for provenance analysis.

关键词： apatite detrital apatite U-Pb age trace elements provenance analysis Yarlung River Tibetan Plateau geochronology

LEO satellite clock analysis and prediction for positioning applications

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Geo-Spatial Information Science 2022年第1期25卷 14-33页

作者： Kan Wang Ahmed El-Mowafy school of earth and Planetary sciences Curtin UniversityPerthAustralia

The positioning service aided by low earth orbit(LEO)mega-constellations has become a hot topic in recent *** achieve precise positioning,accuracy of the LEO clocks is important for single-receiver *** bridge the gap between the applicable time of the clock products and the time of positioning,the precise LEO clocks need to be predicted over a certain period depending on the sampling interval of the clock *** study discusses the prediction errors for periods from 10 s to 1 h for two typical LEO clock types,*** ultra-stable oscillator(USO)and the oven-controlled crystal oscillator(OCXO).The prediction is based on GNSS-determined precise clock estimates,where the clock stability is related to the GNSS estimation errors,the behaviors of the oscillators themselves,the systematic effects related to the environment and the relativistic effects,and the stability of the time *** on real data analysis,LEO clocks of the two different types are simulated under different conditions,and a prediction model considering the systematic effects is *** to a simple polynomial fitting model usually applied,the proposed model can significantly reduce the prediction errors,*** about 40%-70%in simulations and about 5%-30%for real data containing different miss-modeled *** both clock types,short-term prediction of 1 min would result in a root mean square error(RMSE)of a few centimeters when using a very stable time *** RMSE amounts to about 0.1 m,when a typical real-time time reference of the national center for space studies(CNES)real-time clocks was *** long-term prediction of 1 h,the RMSE could range from below 1 m to a few meters for the USOs,depending on the complexity of the miss-modeled *** OCXOs,the 1 h prediction could lead to larger errors with an RMSE of about 10 m.

关键词： LEO clock prediction USO OCXO relativistic effects

New Insights into Petroleum Migration-Accumulation Dynamic Systems and Their Division within Petroleum Systems

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Journal of earth Science 2012年第5期23卷 744-756页

作者：赵靖舟 Ihsan S Al-aasm school of earth sciences and Engineering Xi'an Shiyou University Department of earth and Environmental sciences University of Windsor

Since the concept of petroleum migration-accumulation dynamic system （PMADS） was introduced in the 1990s, its definition, division and even denomination have long been in disagreement. This article aims to further discuss and try to clarify this concept and to explore more reasonable approaches to the division of PMADSs on the basis of our studies on petroleum migration and accumulation in some pe- troliferous basins of China, especially those from western China. According to the studies, we define PMADS as a relatively independent natural hydrocarbon migrating and accumulating system within a petroleum system. Its extent is supposed to cover the whole migration pathway starting from a hydrocarbon provenance throughout to an accumulation or a group of accumulations of same source. Just like petroleum systems, a petroleum migration-accumulation system is also an important natural unit for petroleum exploration and assessment in petroleum basins. Its position in a basin is right between a petroleum system and a play. A pe- troleum system has either a number of migration-accumulation systems or one system only. However, the key element of a petroleum system is the source of hydrocarbon; a petroleum system has a distinct hydrocarbon kitchen and is different from its neighboring ones in terms of hydrocarbon kitchens. In contrast, different migration-accumulation systems within the same petroleum system have a shared source kitchen but differ-ent characteristics of migration and accumulation to form hydrocarbon accumulations. As far as the division of petroleum migration-accumulation systems （PMASs） is concerned, 8 major approaches are proposed, including those based on pool-forming dynamic mechanisms, location of hydrocarbon accumulation rela- tive to the source kitchen, phase states of migration and accumulation, migration patterns and directions, geneses of accumulations, reservoir pressure systems, depositional systems and facies, and integrated method, of which the

关键词： petroleum migration accumula-tion migration-accumulation system petroleumsystem.

Influential Intensity of Urban Agglomeration on Evolution of Ecoenvironmental Pressure:A Case Study of Changchun,China

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Chinese Geographical Science 2017年第4期27卷 638-647页

作者： LIU Yanjun ZHANG Jing LI Chenggu ZHOU Guolei FU Zhanhui LIU Degang school of geography sciences Northeast Normal UniversityChangchun 130024China

In this paper,we study the interactive relationship between the agglomeration of urban elements and the evolution of eco-environmental *** build an index system for evaluating the agglomeration of urban elements and eco-environmental *** the entropy method and response intensity model,we analyze how urban elements agglomeration influenced eco-environmental pressure in Changchun from 1990 to 2012,eliciting the changing features and influential ***,we conclude there is a significant interactive relationship between the agglomeration of urban elements and the evolution of eco-environmental pressure in *** is inferred from the degree of this agglomeration in Changchun having increased since 1990,with the degree of eco-environmental pressure first decreasing and then *** this,the impact of urban elements agglomeration on eco-environmental pressure has changed from negative to *** main reasons behind this shift are arguably the rapid growth of urban investment and ongoing urbanization.

关键词： urban elements agglomeration eco-environmental pressure influential intensity response index Changchun China

Oil-bearing fluid inclusions from the Palaeoproterozoic:A review of biogeochemical results from time-capsules >2.0 Ga old

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Science China earth sciences 2009年第1期52卷 1-11页

作者： Simon C. GEORGE Adriana DUTKIEWICZ Herbert VOLK John RIDLEY David J. MOSSMAN Roger BUICK Department of earth and Planetary sciences Macquarie University school of Geosciences University of Sydney CSIRO Petroleum Department of Geosciences Colorado State University Department of geography Mount Allison University Department of earth and Space sciences & Astrobiology Program University of Washington

The observation of oil inclusions trapped prior to 2.0 Ga in Palaeoproterozoic rocks and the ability to obtain detailed molecular geochemical information from them provide a robust way for understanding the early biog... 详细信息

关键词： Palaeoproterozoic fluid inclusion oil biomarker blank

Resolution Increase and Noise Removal in Particle Size Distribution Measurement with Shifrin Transform

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Transactions of Nanjing University of Aeronautics and Astronautics 2015年第4期32卷 446-451页

作者：韩月杨宗苓乔星钱鹏袁银男丁思红戴兵 school of sciences Nantong University school of Mechanical Engineering Nantong University school of geography Nantong University

Based on the laser diffraction and Shifrin transform,the measurement method of particle size distribution has been improved *** in real measurements,some noise peaks exist in the inversion data and are easily to be misread as particle distribution *** improved method used a truncation function as a filter is hard to distinguish adjacent ***,by introducing the bimodal resolution criterion,the filter function is optimized,and to a quasi truncation function with the optimized filter function is studied to achieve optimal bimodal resolution and to remove noise *** new quasi truncation function fits multimode distribution very *** combining the quasi truncation function with Shifrin transform,noise peaks are removed well and the adjacent peaks are distinguished ***,laser diffraction experiments are conducted and the particle size distribution is analyzed by adoping the *** results show that the quasi truncation function has better bimodal resolution than the truncation ***,by combining the quasi truncation function with the Shifrin transform,in particle size distribution measurements with laser diffraction,the bimodal resolution is greatly increased and the noise is removed *** the results can restore the original distribution ***,the new method with combination of the quasi truncation function and the Shifrin transform provides a feasible and effective way to measure the multimode particle size distribution by laser diffraction.

关键词： diffraction particle size distribution Shifrin transform quasi truncation function inversion