Comprehensive studies on the basis of pollen records from lake cores at 30 sites in the Qinghai-Xizang Plateau have been used to reconstruct temporal-spatial distributions of Holocene vegetations. Before the, Holocene...Comprehensive studies on the basis of pollen records from lake cores at 30 sites in the Qinghai-Xizang Plateau have been used to reconstruct temporal-spatial distributions of Holocene vegetations. Before the, Holocene (prior to 12.0 ka BP) desert steppe vegetation was developed from the, east to the west in the most parts of the Plateau, with a few exceptions in the extreme southeastern appeared. During the early Holocene ( 12.0 - 9.0 ka BP) deciduous broad-leaved forest/conifer and broad-leaved deciduous mixed forest were distributed in the east of Plateau (104degrees - 98degrees E). Meadows or shrub, meadow appeared in the middle of tire Plateau (98degrees - 92degrees E). Farther west to about 80degrees E, a steppe landscape was present. During the middle Holocene (9.0 - 3.2 ka BP), the palaeovegetations were sequentially conifer and broad-leaved deciduous mixed forest and sclerophyllous broad-leaved forest (104degrees - 98degrees E) - conifer and broad-leaved deciduous mixed forest (98degrees - 94degrees E) - shrub meadow (94degrees - 92degrees E) - steppe (92degrees - 80degrees E). During the late Holocene (after 3.2 ka BP), the palaeovegetations were sequentially sclerophyllous broad-leaved forest - conifer and broad-leaved deciduous mixed forest - meadow - steppe - desert from east to west of the Plateau.展开更多
In order to well protect Chinese ancient buildings, aseismic behaviors of Chinese ancient tenon-mortise joints strengthened by carbon fibre reinforced plastic （CFRP） are studied by experiments. Based on the actual s...In order to well protect Chinese ancient buildings, aseismic behaviors of Chinese ancient tenon-mortise joints strengthened by carbon fibre reinforced plastic （CFRP） are studied by experiments. Based on the actual size of an ancient building, a wooden frame model with a scale of 1 ： 8 of the prototype structure is built considering the swallow-tail type of tenon-mortise connections. Low cyclic reversed loading tests are carried out including three groups of unstrengthened structures and two groups of structures strengthened with CFRP. Based on experimental data, moment-rotation angle hysteretic curves and skeleton curves for each joint are obtained. The energy dissipation capability, stiffness degradation and deformation performance of the joints before and after being strengthened are also analyzed. Results show that after being strengthened with CFRP, the tenon value pulled out of the mortise is reduced; the bending strength and the energy dissipation capabilities of the joint are enhanced; stiffness degradation of the joint is not obvious; and the deformation performance of the joint remains good. Thus, the CFRP has good effects on strengthening the tenon-mortise joints of Chinese ancient buildings.展开更多
Erdaohezi lead-zinc deposit belongs to the Derbugan metallogenic belt lying on the northwestern Hailaer-Genhe Mesozoic volcanic basin, located on the western slope of the Da Hinggan Mountains. The deposit is considere...Erdaohezi lead-zinc deposit belongs to the Derbugan metallogenic belt lying on the northwestern Hailaer-Genhe Mesozoic volcanic basin, located on the western slope of the Da Hinggan Mountains. The deposit is considered as one of the hypabyssal low-temprature hydrothermal lead-zinc deposits associated with volca- nism. In order to lay the foundation on studying its diagenesis and mineralization ages, the detailed studies were carried out by dating the host rocks （i. e. rhyolitic lithic-crystal tufts） using zircon LA-ICP-MS U-Pb method. The dating results show three groups ot! ages. The first group is the captured zircons （the weighted mean ^206pb/238U age as 175.6± 2.3 Ma, MSWD = 0.70, n = 3）. The second group can be regarded as the rock- forming age （the weighted mean ^206pb/238U age as 165.3± 1.9 Ma, MSWD = 2.40, n = 14）. The third group should represent the late stage of the magmatic evolution （the weighted mean ^206pb/238U age as 161.0 ± 3.1 Ma, MSWD = 0.86, n = 4）. According to the ages and the crystal form or CL image characteristics of zircons, it is determined that the diagenesis occurred in the late Middle Jurassic. Based on the regional geology and geo- chronological research, the acidic pyroclastic rocks are space accompaniment and time connection with the Tamu- langou Formation intermediate-mafic volcanic rocks. Both of them constitute the host rocks of the deposit together. The rock combination also provides favorable conditions for large-scale silver, lead and zinc mineralization in this area.展开更多
For most networks, the weight of connection is changing with their attachment and inner affinity. By introducing a mixed mechanism of weighted-driven and inner selection, the model exhibits wide range power-law distri...For most networks, the weight of connection is changing with their attachment and inner affinity. By introducing a mixed mechanism of weighted-driven and inner selection, the model exhibits wide range power-law distributions of node strength and edge weight, and the exponent can be adjusted by not only the parameter δ but also the probability q. Furthermore, we investigate the weighted average shortest distance, clustering coefficient, and the correlation of our network. In addition, the weighted assortativity coefficient which characterizes important information of weighted topological networks has been discussed, but the variation of coefficients is much smaller than the former researches.展开更多
Petrographic analysis combined with various techniques, such as thin section identification, petro-physical property testing, mercury penetration, oil testing results, was used to assess basic reservoir characteristic...Petrographic analysis combined with various techniques, such as thin section identification, petro-physical property testing, mercury penetration, oil testing results, was used to assess basic reservoir characteristics of deep strata in Palaeogene in the northern steep slope zone of the Bonan sag, China. The formation mechanisms of high quality reservoirs in deep strata were discussed according to evolution characteristics of paleopressures and paleofluids in geological period. The deep reservoirs have poor physical properties and mainly develop extra-low porosity, extra-low and ultra-low permeability reservoirs. Reservoir spaces mainly consist of secondary pores and overpressure fractures. Early overpressure, early hydrocarbon filling and dissolution by early organic acids are the major formation mechanisms of high quality reservoirs. The conglomerate in inner fan which had a poor primary physical property mainly experienced strong compaction and calcareous matrix recrystallization. The physical properties of the inner fan were poor with weak dissolution because of poor mobility of fluid. The reservoirs mainly are type IV reservoirs and the distribution extends with the burial depth. The braided channel reservoirs in the middle fan had relative good primary physical properties and strong ability to resist compaction which favored the preservation of primary pores. Large amounts of the secondary porosities were created due to dissolution by early organic acids. A series of micro-fractures generated by early overpressures would be important migration pathways for hydrocarbon and organic acids. Furthermore, early overpressures had retarded maturation of organic matters and organic acids which had flowed into reservoirs already and could keep in acid environment for a long time. This process would contribute significantly to reinforcing the dissolution and enhancing the reservoir quality. The braided channel reservoirs were charged with high oil saturation preferentially by early hydrocarbon filling which could inhibit later cementation. Therefore, the braided channel reservoirs develop a great quantity of reservoir spaces with type I, type II and type III reservoirs in the majority in the deep strata. With the burial depth, distributions of type I and type II reservoirs are narrowed and distribution of type III reservoirs decreases first and then extends. The reservoirs both in outer fan and in interdistributary of the middle fan have extremely poor physical properties because of extensive carbonate cementation. The type of the reservoirs mainly is type IV.展开更多
There are about 19 Neolithic Age sites and 120 Shang-Zhou dynasties sites in the western lakeshore of Chaohu Lake,Anhui Province,China.Based on sites data,topographic data,drainage maps,administrative maps and SPOT5 r...There are about 19 Neolithic Age sites and 120 Shang-Zhou dynasties sites in the western lakeshore of Chaohu Lake,Anhui Province,China.Based on sites data,topographic data,drainage maps,administrative maps and SPOT5 remote sensing data,spatial analysis methods were introduced into the archaeology of Chaohu Lake Basin with Geographic Information System(GIS).The spatial analysis methods include:1) Point Density Analysis with density model to acquire the shift of the sites;2) Distance Analysis to reveal the spatial structure of the sites;3) 3D Analysis based on Digital Elevation Model to get micro-geomorphologic features of the sites;and 4) Buffer Analysis to discover the relationship between the sites and rivers.The results indicate that the archaeological sites spread from the western lakeshore of Chaohu Lake gradually to the northwest,later to the south,and then symmetrically spread.Controlled by productive forces and other factors,ancient people preferred to reside in those places near water,or in plain and fertile land,which resulted in linear and decentralized distribution of the sites,and presented such disciplines as river valley directivity,terrace directivity and soil directivity.This paper indicates that the distribution of archaeological sites was influenced earlier by natural elements and later by human elements in the study period.The research is important for the integration of GIS and archaeology.展开更多
文摘Comprehensive studies on the basis of pollen records from lake cores at 30 sites in the Qinghai-Xizang Plateau have been used to reconstruct temporal-spatial distributions of Holocene vegetations. Before the, Holocene (prior to 12.0 ka BP) desert steppe vegetation was developed from the, east to the west in the most parts of the Plateau, with a few exceptions in the extreme southeastern appeared. During the early Holocene ( 12.0 - 9.0 ka BP) deciduous broad-leaved forest/conifer and broad-leaved deciduous mixed forest were distributed in the east of Plateau (104degrees - 98degrees E). Meadows or shrub, meadow appeared in the middle of tire Plateau (98degrees - 92degrees E). Farther west to about 80degrees E, a steppe landscape was present. During the middle Holocene (9.0 - 3.2 ka BP), the palaeovegetations were sequentially conifer and broad-leaved deciduous mixed forest and sclerophyllous broad-leaved forest (104degrees - 98degrees E) - conifer and broad-leaved deciduous mixed forest (98degrees - 94degrees E) - shrub meadow (94degrees - 92degrees E) - steppe (92degrees - 80degrees E). During the late Holocene (after 3.2 ka BP), the palaeovegetations were sequentially sclerophyllous broad-leaved forest - conifer and broad-leaved deciduous mixed forest - meadow - steppe - desert from east to west of the Plateau.
基金The Cultural Ministry Foundation of China(No.17-2009)the Research Foundation of Palace Museum(No.2007-4)
文摘In order to well protect Chinese ancient buildings, aseismic behaviors of Chinese ancient tenon-mortise joints strengthened by carbon fibre reinforced plastic （CFRP） are studied by experiments. Based on the actual size of an ancient building, a wooden frame model with a scale of 1 ： 8 of the prototype structure is built considering the swallow-tail type of tenon-mortise connections. Low cyclic reversed loading tests are carried out including three groups of unstrengthened structures and two groups of structures strengthened with CFRP. Based on experimental data, moment-rotation angle hysteretic curves and skeleton curves for each joint are obtained. The energy dissipation capability, stiffness degradation and deformation performance of the joints before and after being strengthened are also analyzed. Results show that after being strengthened with CFRP, the tenon value pulled out of the mortise is reduced; the bending strength and the energy dissipation capabilities of the joint are enhanced; stiffness degradation of the joint is not obvious; and the deformation performance of the joint remains good. Thus, the CFRP has good effects on strengthening the tenon-mortise joints of Chinese ancient buildings.
基金Supported by National Natural Science Foundation of China(No.41390444)
文摘Erdaohezi lead-zinc deposit belongs to the Derbugan metallogenic belt lying on the northwestern Hailaer-Genhe Mesozoic volcanic basin, located on the western slope of the Da Hinggan Mountains. The deposit is considered as one of the hypabyssal low-temprature hydrothermal lead-zinc deposits associated with volca- nism. In order to lay the foundation on studying its diagenesis and mineralization ages, the detailed studies were carried out by dating the host rocks （i. e. rhyolitic lithic-crystal tufts） using zircon LA-ICP-MS U-Pb method. The dating results show three groups ot! ages. The first group is the captured zircons （the weighted mean ^206pb/238U age as 175.6± 2.3 Ma, MSWD = 0.70, n = 3）. The second group can be regarded as the rock- forming age （the weighted mean ^206pb/238U age as 165.3± 1.9 Ma, MSWD = 2.40, n = 14）. The third group should represent the late stage of the magmatic evolution （the weighted mean ^206pb/238U age as 161.0 ± 3.1 Ma, MSWD = 0.86, n = 4）. According to the ages and the crystal form or CL image characteristics of zircons, it is determined that the diagenesis occurred in the late Middle Jurassic. Based on the regional geology and geo- chronological research, the acidic pyroclastic rocks are space accompaniment and time connection with the Tamu- langou Formation intermediate-mafic volcanic rocks. Both of them constitute the host rocks of the deposit together. The rock combination also provides favorable conditions for large-scale silver, lead and zinc mineralization in this area.
基金supported by the National Natural Science Foundation of China under Grant No.10675060
文摘For most networks, the weight of connection is changing with their attachment and inner affinity. By introducing a mixed mechanism of weighted-driven and inner selection, the model exhibits wide range power-law distributions of node strength and edge weight, and the exponent can be adjusted by not only the parameter δ but also the probability q. Furthermore, we investigate the weighted average shortest distance, clustering coefficient, and the correlation of our network. In addition, the weighted assortativity coefficient which characterizes important information of weighted topological networks has been discussed, but the variation of coefficients is much smaller than the former researches.
基金Project(41102058)supported by the National Natural Science Foundation of ChinaProject(2011ZX05006-003)supported by National Oil&Gas Major Project of China+1 种基金Project(U1262203)supported by Key Program for National Natural Science Foundation of ChinaProject(LW140101A)supported by Excellent Doctoral Dissertation Program of China University of Petroleum
文摘Petrographic analysis combined with various techniques, such as thin section identification, petro-physical property testing, mercury penetration, oil testing results, was used to assess basic reservoir characteristics of deep strata in Palaeogene in the northern steep slope zone of the Bonan sag, China. The formation mechanisms of high quality reservoirs in deep strata were discussed according to evolution characteristics of paleopressures and paleofluids in geological period. The deep reservoirs have poor physical properties and mainly develop extra-low porosity, extra-low and ultra-low permeability reservoirs. Reservoir spaces mainly consist of secondary pores and overpressure fractures. Early overpressure, early hydrocarbon filling and dissolution by early organic acids are the major formation mechanisms of high quality reservoirs. The conglomerate in inner fan which had a poor primary physical property mainly experienced strong compaction and calcareous matrix recrystallization. The physical properties of the inner fan were poor with weak dissolution because of poor mobility of fluid. The reservoirs mainly are type IV reservoirs and the distribution extends with the burial depth. The braided channel reservoirs in the middle fan had relative good primary physical properties and strong ability to resist compaction which favored the preservation of primary pores. Large amounts of the secondary porosities were created due to dissolution by early organic acids. A series of micro-fractures generated by early overpressures would be important migration pathways for hydrocarbon and organic acids. Furthermore, early overpressures had retarded maturation of organic matters and organic acids which had flowed into reservoirs already and could keep in acid environment for a long time. This process would contribute significantly to reinforcing the dissolution and enhancing the reservoir quality. The braided channel reservoirs were charged with high oil saturation preferentially by early hydrocarbon filling which could inhibit later cementation. Therefore, the braided channel reservoirs develop a great quantity of reservoir spaces with type I, type II and type III reservoirs in the majority in the deep strata. With the burial depth, distributions of type I and type II reservoirs are narrowed and distribution of type III reservoirs decreases first and then extends. The reservoirs both in outer fan and in interdistributary of the middle fan have extremely poor physical properties because of extensive carbonate cementation. The type of the reservoirs mainly is type IV.
基金Under the auspices of National Natural Science Foundation of China (No 40571162)Education Department of Anhui Province Foundation (No 2007sk097)Natural Science Foundation of Anhui (No 090415212),Program for Innovative Research Team in Anhui Normal University
文摘There are about 19 Neolithic Age sites and 120 Shang-Zhou dynasties sites in the western lakeshore of Chaohu Lake,Anhui Province,China.Based on sites data,topographic data,drainage maps,administrative maps and SPOT5 remote sensing data,spatial analysis methods were introduced into the archaeology of Chaohu Lake Basin with Geographic Information System(GIS).The spatial analysis methods include:1) Point Density Analysis with density model to acquire the shift of the sites;2) Distance Analysis to reveal the spatial structure of the sites;3) 3D Analysis based on Digital Elevation Model to get micro-geomorphologic features of the sites;and 4) Buffer Analysis to discover the relationship between the sites and rivers.The results indicate that the archaeological sites spread from the western lakeshore of Chaohu Lake gradually to the northwest,later to the south,and then symmetrically spread.Controlled by productive forces and other factors,ancient people preferred to reside in those places near water,or in plain and fertile land,which resulted in linear and decentralized distribution of the sites,and presented such disciplines as river valley directivity,terrace directivity and soil directivity.This paper indicates that the distribution of archaeological sites was influenced earlier by natural elements and later by human elements in the study period.The research is important for the integration of GIS and archaeology.
