Surveys was conducted to study the population density and habitat utilization of the ibex （Capra ibex） in Tomur National Nature Reserve during October- December 2005. The results are as follows： ① The mean group s...Surveys was conducted to study the population density and habitat utilization of the ibex （Capra ibex） in Tomur National Nature Reserve during October- December 2005. The results are as follows： ① The mean group size of the ibex in Tomur Nature Reserve is 8.43 and the population density is 269.76/100 km^2; ② The ibex prefer areas with steep slope （between 30° -45°）, broken substrates and cliffs nearby （ 〈 100 m）. They avoid grasslands and fiat hillsides; ③The probable reason for this habitat selection is serf-protection.展开更多
Sensitivity evaluation of rocky desertification is to recognize the areas prone to be rock-deserted,so as to assess the sensitivity degree of rocky desertification to human activities.To perform the sensitivity evalua...Sensitivity evaluation of rocky desertification is to recognize the areas prone to be rock-deserted,so as to assess the sensitivity degree of rocky desertification to human activities.To perform the sensitivity evaluation of rocky desertification,we should be on the basis of the mechanism of rocky desertification formation for analyzing its regional distribution difference in the sensitivity and further for finding out the rocky desertification-susceptive areas and their possible degrees.Employing remote sensing and geological information system techniques,we regarded the 1∶ 50 000 topographic map and the TM image in 2000 of Guizhou Province,together with the hydrologic map,soil map,geologic map,rock formation map,administrative map and other geological information as data sources to generate the degree data of rocky desertification sensitivity of Guizhou Province in 1962 and 2000,based on which we determined the corresponding degree transfer matrix and adopted Markov model to simulate the dynamic change process of rocky desertification sensitivity and its future evolution trend.In various sensitivity types of rocky desertification in Guizhou Province,only the insensitive type showed a declined acreage,from the proportion of total land acreage of 61.35% in 1962 to 55.55% in 2000.Various sensitivity types inter-conversed,resultantly the acreage of mildly sensitive type increased most.The prediction results showed that the acreage of insensitive type of rocky desertification in Guizhou Province will assume a remarkable decline trend,of mildly sensitive type will present a remarkably increasing trend and of slightly sensitive type basically will maintain a stable level in the future tens of years.Acreages of both highly sensitive and extremely sensitive type of rocky desertification expanded to some extent,suggesting that the rocky desertification risk in Guizhou Province is in an aggravating process.展开更多
In seismic data processing, random noise seriously affects the seismic data quality and subsequently the interpretation. This study aims to increase the signal-to-noise ratio by suppressing random noise and improve th...In seismic data processing, random noise seriously affects the seismic data quality and subsequently the interpretation. This study aims to increase the signal-to-noise ratio by suppressing random noise and improve the accuracy of seismic data interpretation without losing useful information. Hence, we propose a structure-oriented polynomial fitting filter. At the core of structure-oriented filtering is the characterization of the structural trend and the realization of nonstationary filtering. First, we analyze the relation of the frequency response between two-dimensional（2D） derivatives and the 2D Hilbert transform. Then, we derive the noniterative seismic local dip operator using the 2D Hilbert transform to obtain the structural trend. Second, we select polynomial fitting as the nonstationary filtering method and expand the application range of the nonstationary polynomial fitting. Finally, we apply variableamplitude polynomial fitting along the direction of the dip to improve the adaptive structureoriented filtering. Model and field seismic data show that the proposed method suppresses the seismic noise while protecting structural information.展开更多
To improve the navigation accuracy of an autonomous underwater vehicle （AUV）, a novel terrain passive integrated navigation system （TPINS） is presented. According to the characteristics of the underwater environme...To improve the navigation accuracy of an autonomous underwater vehicle （AUV）, a novel terrain passive integrated navigation system （TPINS） is presented. According to the characteristics of the underwater environment and AUV navigation requirements of low cost and high accuracy, a novel TPINS is designed with a configuration of the strapdown inertial navigation system （SINS）, the terrain reference navigation system （TRNS）, the Doppler velocity sonar （DVS）, the magnetic compass and the navigation computer utilizing the unscented Kalman filter （UKF） to fuse the navigation information from various navigation sensors. Linear filter equations for the extended Kalman filter （EKF）, nonlinear filter equations for the UKF and measurement equations of navigation sensors are addressed. It is indicated from the comparable simulation experiments of the EKF and the UKF that AUV navigation precision is improved substantially with the proposed sensors and the UKF when compared to the EKF. The TPINS designed with the proposed sensors and the UKF is effective in reducing AUV navigation position errors and improving the stability and precision of the AUV underwater integrated navigation.展开更多
The cardiac and vascular effect of ethanolamine nitrate ester ferulate (ENF) wasinvestigated on isolated working guinea pig heart (IWH) and rat aortic ring. The coronary blood flowwas remarkably increased while the c...The cardiac and vascular effect of ethanolamine nitrate ester ferulate (ENF) wasinvestigated on isolated working guinea pig heart (IWH) and rat aortic ring. The coronary blood flowwas remarkably increased while the cardiac functions of IWH were not significantly altered by ENFranging from 10-8 to 10-4 mol/L. The percentages of vasorelaxation of ENF t 10 μmol/L) and nicoran-dil (NIC, 10 μmol/L) on K+ (80 mmol/L)-induced contraction in aortic rings were 72 ± 8% and17±8%, respectively. The relaxation effects of ENF and NIC on phenylephrine (PE, 5 μmol/L) in-duced contraction were in a dose-dependent manner. When vessel segments were exposed to PE withmethylene blue (MB, 10 μmol/L) or with glibenclamide (GLI, 10 pmol/L), the percentages of relaxa-tion of ENF (10 μmol/L) and NIC ( 1 0 μmol/L) were 4 1 ±11 % and 49±7% or 76± 14% and the 33±9%,respectively. The results suggested that ENF improved coronary circulation and the vasodilation of ENF was mediated bv nitrate-like action.展开更多
To keep the tunnel face stable is very important for tunnel construction.In this paper,the tunnel face stability under the advanced pipe was analyzed using the Winkler foundation model and rigid limit equilibrium.The ...To keep the tunnel face stable is very important for tunnel construction.In this paper,the tunnel face stability under the advanced pipe was analyzed using the Winkler foundation model and rigid limit equilibrium.The tunnel face deformation characteristics were also analyzed using the numerical simulation.The influence of parameters on the deflection of the pipe roof and the stability of the tunnel face were discussed.The results show that the tunnel face stability can be improved through increasing the pipe diameter,decreasing the initial displacement at the beginning of the pipe seat,and adopting the short round length and small excavation height.With the increase of tunnel burial depth,the safety factor of tunnel face stability first decreases,then increases,and then remains unchanged.The deformation at the center of the tunnel face is larger than the deformation at the surround sides and at the corner.The horizontal displacement varies little with the increasing of the pipe length.The horizontal displacement at the center of the tunnel face increases with the increase of the pipe ring spacing and the pipe longitudinal spacing.There is an optimum external angle.展开更多
Morpho-tectonic study plays an important role in deciphering the effects of tectonic activity in the geomorphic evolution of the drainage basins.Romushi watershed forms one of the major watersheds of the intermontane ...Morpho-tectonic study plays an important role in deciphering the effects of tectonic activity in the geomorphic evolution of the drainage basins.Romushi watershed forms one of the major watersheds of the intermontane Karewa Basin of Kashmir Valley.The Karewa sediments are characterized by glacio-fluvio-lacustrine deposits capped by the aeolian loess.The geomorphic,morphometric and lithostratigraphic studies of these cap deposits have been carried out to elucidate the effect of tectonics on the geomorphic evolution of Romushi Watershed.Geomorphic mapping was carried out using GPS measurements,DEM at 30m resolution,Topographic Position Index(TPI) model,topographic maps,LANDSAT TM Imagery and field data.Morphometric and morphotectonic analyses in GIS environment were used to calculate various geomorphic indices(Mountain Front Sinuosity Index,Bifurcation Ratio,Asymmetry Factor,River Profile,etc).These indices reveal that the tectonic uplift observed in the region due to Himalayan orogeny coupled with mass movement and aeolian deposition have dominated the landscape evolution of intermontane Karewa Basin of Kashmir throughout the Late Quaternary Period.Additional data from lithostratigraphic measurements were analyzed to understand the geomorphic evolution of intermontane Karewa Basin.The data revealed that the basin has experienced differential uplift and erosion rates from time to time in the geological past.This was corroborated by the results from the morphometric and morphotectonic analysis.展开更多
Are there some relationships among species diversity and soil chemical properties of high altitude natural grasslands? Plant community composition and chemical properties of soil samples were compared to investigate t...Are there some relationships among species diversity and soil chemical properties of high altitude natural grasslands? Plant community composition and chemical properties of soil samples were compared to investigate the relationship between soil and species diversity, and the richness in Tibetan alpine grasslands. Results showed that species diversity was significantly positively related to soil organic matter(SOM), total nitrogen(TN),available nitrogen(AN), total phosphorus(TP),available phosphorus(AP), and available potassium(AK) in the high alpine grasslands. Margalef's species richness index was also significantly positively related to SOM, TN, AN, and TP. Most soil chemical properties showed significantly positive correlation with species diversity and Margalef's richness index.Our results suggested that higher plant species richness index and diversity occurred in more fertile soil habitats in high altitude natural grassland community. In practice, fertilization management for the restoration of degraded grassland should be conducted with reference to the nutrient levels ofnatural grassland without the additional artificial fertilizer and with higher species-diversity and richness index.展开更多
Based on the element geochemistry and biomarkers of the oil shale from the Chang 7 sub-unit in the southern Ordos Basin,the depositional conditions and organic source of the oil shale are discussed.Biomarkers analyses...Based on the element geochemistry and biomarkers of the oil shale from the Chang 7 sub-unit in the southern Ordos Basin,the depositional conditions and organic source of the oil shale are discussed.Biomarkers analyses show that the oil shale has a homologous organic matter source,with a mix of plankton and advanced plants.U/Th and V/Ni ratios suggest that the redox condition is dominated by a reducing condition,and the degree of anoxia in the Tongchuan area is higher than that of the Xunyi area.Sr/Ba ratios illustrate that the oil shale is deposited in fresh water and the paleosalinity in the Tongchuan area is slightly higher.Fe/Ti ratios imply that the Tongchuan area underwent obvious hydrothermal fluid activities.Sr/Cu ratios show warm and humid paleoclimate in both areas.As assessed by(La/Yb)NASC,the deposition rate in the Tongchuan area is relatively lower.Fe/Co and Th/U ratios suggest that the paleo-water-depth in the Tongchuan area is deeper.The source rock could have the advance plants source,which must have close relationship with the Qinling orogeny.Comparing the paleoenvironment,the Tongchuan area has better depositional conditions,and is the key oil shale exploration area in the southern Ordos Basin.展开更多
Seismic inversion is a highly ill-posed problem, due to many factors such as the limited seismic frequency bandwidth and inappropriate forward modeling. To obtain a unique solution, some smoothing constraints, e.g., t...Seismic inversion is a highly ill-posed problem, due to many factors such as the limited seismic frequency bandwidth and inappropriate forward modeling. To obtain a unique solution, some smoothing constraints, e.g., the Tikhonov regularization are usually applied. The Tikhonov method can maintain a global smooth solution, but cause a fuzzy structure edge. In this paper we use Huber-Markov random-field edge protection method in the procedure of inverting three parameters, P-velocity, S-velocity and density. The method can avoid blurring the structure edge and resist noise. For the parameter to be inverted, the Huber- Markov random-field constructs a neighborhood system, which further acts as the vertical and lateral constraints. We use a quadratic Huber edge penalty function within the layer to suppress noise and a linear one on the edges to avoid a fuzzy result. The effectiveness of our method is proved by inverting the synthetic data without and with noises. The relationship between the adopted constraints and the inversion results is analyzed as well.展开更多
The basic granulite of the Altay orogenic belt occurs as tectonic lens in the Devonian medium- to lower-grade metamorphic beds through fault contact. The Altay granulite (AG) is an amphibole plagioclase two-pyroxene ...The basic granulite of the Altay orogenic belt occurs as tectonic lens in the Devonian medium- to lower-grade metamorphic beds through fault contact. The Altay granulite (AG) is an amphibole plagioclase two-pyroxene granulite and is mainly composed of two pyroxenes, plagioclase, amphibole and biotite. Its melano-minerals are rich in Mg/(Mg+Fe2+), and its amphibole and biotite are rich in TiO2. The AG is rich in Mg/(Mg+Fe2+), Al2O3 and depletion of U, Th and Rb contents. The AG has moderate ∑REE and LREE-enriched with weak positive Eu anomaly. The AG shows island-arc pattern with negative Nb, P and Ti anomalies, reflecting that formation of the AG may be associated with subduction. Geochemical and mineral composition data reflect that the protolith of the AG is calc-alkaline basalt and formed by granulite facies metamorphism having peak P-T conditions of 750 °C?780 °C and 0.6?0.7 Gpa. The AG formation underwent two stages was suggested. In the early stage of oceanic crustal subduction, calc-alkaline basalt with island-arc environment underwent granulite facies metamorphism to form the AG in deep crust, and in the late stage, the AG was thrust into the upper crust.展开更多
Compared with traditional real-time forecasting,this paper proposes a Grey Markov Model(GMM) to forecast the maximum water levels at hydrological stations in the estuary area.The GMM combines the Grey System and Marko...Compared with traditional real-time forecasting,this paper proposes a Grey Markov Model(GMM) to forecast the maximum water levels at hydrological stations in the estuary area.The GMM combines the Grey System and Markov theory into a higher precision model.The GMM takes advantage of the Grey System to predict the trend values and uses the Markov theory to forecast fluctuation values,and thus gives forecast results involving two aspects of information.The procedure for forecasting annul maximum water levels with the GMM contains five main steps:1) establish the GM(1,1) model based on the data series;2) estimate the trend values;3) establish a Markov Model based on relative error series;4) modify the relative errors caused in step 2,and then obtain the relative errors of the second order estimation;5) compare the results with measured data and estimate the accuracy.The historical water level records(from 1960 to 1992) at Yuqiao Hydrological Station in the estuary area of the Haihe River near Tianjin,China are utilized to calibrate and verify the proposed model according to the above steps.Every 25 years' data are regarded as a hydro-sequence.Eight groups of simulated results show reasonable agreement between the predicted values and the measured data.The GMM is also applied to the 10 other hydrological stations in the same estuary.The forecast results for all of the hydrological stations are good or acceptable.The feasibility and effectiveness of this new forecasting model have been proved in this paper.展开更多
Meromictic soda and saline lakes are unique ecosystems characterized by the stability of physical,chemical and biological parameters,and they are distributed all over the world.Lakes located in regions with average an...Meromictic soda and saline lakes are unique ecosystems characterized by the stability of physical,chemical and biological parameters,and they are distributed all over the world.Lakes located in regions with average annual negative air temperature are of particular interest because of the presence of two periods with intensive and dynamic processes:the so-called biological summer and the long ice season with the biological spring.Soda Lake Doroninskoe is located in Eastern Transbaikalia(51°14′N,112°14′E) in the permafrost zone in an extreme continental climate,and is covered by ice for seven months per year.The structure and diversity of the microbial communities throughout the water column of the lake was studied by 16 S r RNA gene amplicon metasequencing.Different species with specific functions were found to dominate at different depths.Metabolically flexible bacteria with a capacity to switch between anoxygenic photosynthesis and aerobic chemotrophic metabolism dominate in soda Lake Doroninskoe.展开更多
Land use and land cover(LULC) in Nepal has undergone constant change over the past few decades due to major changes caused by anthropogenic and natural factors and their impacts on the national and regional environmen...Land use and land cover(LULC) in Nepal has undergone constant change over the past few decades due to major changes caused by anthropogenic and natural factors and their impacts on the national and regional environment and climate.This comprehensive review of past and present studies of land use and land cover change(LUCC) in Nepal concentrates on cropland, grassland, forest, snow/glacier cover and urban areas. While most small area studies have gathered data from different sources and research over a short period, across large areas most historical studies have been based on aerial photographs such as the Land Resource Mapping Project in 1986. The recent trend in studies in Nepal is to focus on new concepts and techniques to analyze LULC status on the basis of satellite imagery, with the help of geographic information system and remote sensing tools. Studies based on historical documents, and historical and recent spatial data on LULC, have clearly shown an increase in cropland areas in Nepal,and present results indicating different rates and magnitudes. A decrease in forest and snow/glacier coverage is reported in most studies. Little information is available on grassland and urban areas from past research. The unprecedented rate of urbanization in Nepal has led to significant urban land changes over the past 30 years. Meanwhile, long term historical LUCC research in Nepal is required for extensive work on spatially explicit reconstructions on the basis of historical and primary data collection, including LULC archives and drivers for future change.展开更多
For thin gas reservoir of low-porosity and low-permeability in the loess desert area, a suite of lateral reservoir prediction techniques has been developed by Changqing Oil Company and the excellent effects achieved i...For thin gas reservoir of low-porosity and low-permeability in the loess desert area, a suite of lateral reservoir prediction techniques has been developed by Changqing Oil Company and the excellent effects achieved in exploration and exploitation in the areas such as Yulin, Wushenqi,Suligemiao, Shenmu etc., so that the Upper Paleozoic gas reserve has been stably increasing for eight years in Changqing Oilfield. The paper analyzed the effects and experience of the application of these techniques in detail.展开更多
A coal burst occurred on 15 April, 2014 at the Austar Coal Mine, located west of Newcastle, NSW,Australia. The burst resulted in fatal injuries to two men working as part of the mining crew at the development face. At...A coal burst occurred on 15 April, 2014 at the Austar Coal Mine, located west of Newcastle, NSW,Australia. The burst resulted in fatal injuries to two men working as part of the mining crew at the development face. At the time, a continuous miner was being used to mine a longwall development gate road through heavily structured coal, at a depth of approximately 550 m. A number of pre-cursor bumps had occurred on previous shifts, emanating from the coal ribs of the roadway, in proximity to the coal face.This paper reviews the geological, geotechnical and mining conditions and circumstances leading up to the coal burst event; and presents and discusses the available evidence and possible interpretations relating to the geomechanical behaviour mechanisms that may have been critical factors in this incident. The paper also discusses some key technical and operational considerations of ground support systems and mining practices and strategies needed for operating in such conditions in the future.展开更多
Based on sounding data from 1975 to 2005 and TM/ETM+ remote sensing images in 1989, 2001 and 2007, the climate changes in Harbin City, Northeast China in recent 30 years were analyzed and forecasted. Results show that...Based on sounding data from 1975 to 2005 and TM/ETM+ remote sensing images in 1989, 2001 and 2007, the climate changes in Harbin City, Northeast China in recent 30 years were analyzed and forecasted. Results show that in the lower troposphere the meridional wind speed and mean annual wind speed decrease, and in the lower stratosphere the temperature decreases while the meridional wind speed increases significantly. In the study area, the climate is becoming warmer and wetter in the middle lower troposphere. The expansion of urban area has great effects on the surface air temperature and the wind speed, leading to the increase of the surface air temperature, the decrease of the surface wind speed, and the increase of the area of urban high temperature zone. The quantitative equations have been established among the surface air temperature, the carbon dioxide (CO2) concentration and the specific humidity (the water vapor content). It is predicted that the future increasing rate of the surface air temperature is 0.85℃/10yr if emission concentration of CO2 remains unchanged; if emission concentration of CO2 decreases to 75%, 50% and 25%, respectively, the surface air temperature will increase 0.65℃/10yr, 0.46℃/10yr and 0.27℃/10yr, respectively. The rise of the surface air temperature in the study area is higher than that of the global mean temperature forecasted by IPCC.展开更多
文摘Surveys was conducted to study the population density and habitat utilization of the ibex （Capra ibex） in Tomur National Nature Reserve during October- December 2005. The results are as follows： ① The mean group size of the ibex in Tomur Nature Reserve is 8.43 and the population density is 269.76/100 km^2; ② The ibex prefer areas with steep slope （between 30° -45°）, broken substrates and cliffs nearby （ 〈 100 m）. They avoid grasslands and fiat hillsides; ③The probable reason for this habitat selection is serf-protection.
基金Supported by Programs for Science and Technology Development of Guizhou Province(20073017,20083022)National Basic Research Program of China(973Program,2006CB403200)~~
文摘Sensitivity evaluation of rocky desertification is to recognize the areas prone to be rock-deserted,so as to assess the sensitivity degree of rocky desertification to human activities.To perform the sensitivity evaluation of rocky desertification,we should be on the basis of the mechanism of rocky desertification formation for analyzing its regional distribution difference in the sensitivity and further for finding out the rocky desertification-susceptive areas and their possible degrees.Employing remote sensing and geological information system techniques,we regarded the 1∶ 50 000 topographic map and the TM image in 2000 of Guizhou Province,together with the hydrologic map,soil map,geologic map,rock formation map,administrative map and other geological information as data sources to generate the degree data of rocky desertification sensitivity of Guizhou Province in 1962 and 2000,based on which we determined the corresponding degree transfer matrix and adopted Markov model to simulate the dynamic change process of rocky desertification sensitivity and its future evolution trend.In various sensitivity types of rocky desertification in Guizhou Province,only the insensitive type showed a declined acreage,from the proportion of total land acreage of 61.35% in 1962 to 55.55% in 2000.Various sensitivity types inter-conversed,resultantly the acreage of mildly sensitive type increased most.The prediction results showed that the acreage of insensitive type of rocky desertification in Guizhou Province will assume a remarkable decline trend,of mildly sensitive type will present a remarkably increasing trend and of slightly sensitive type basically will maintain a stable level in the future tens of years.Acreages of both highly sensitive and extremely sensitive type of rocky desertification expanded to some extent,suggesting that the rocky desertification risk in Guizhou Province is in an aggravating process.
基金Research supported by the 863 Program of China(No.2012AA09A20103)the National Natural Science Foundation of China(No.41274119,No.41174080,and No.41004041)
文摘In seismic data processing, random noise seriously affects the seismic data quality and subsequently the interpretation. This study aims to increase the signal-to-noise ratio by suppressing random noise and improve the accuracy of seismic data interpretation without losing useful information. Hence, we propose a structure-oriented polynomial fitting filter. At the core of structure-oriented filtering is the characterization of the structural trend and the realization of nonstationary filtering. First, we analyze the relation of the frequency response between two-dimensional（2D） derivatives and the 2D Hilbert transform. Then, we derive the noniterative seismic local dip operator using the 2D Hilbert transform to obtain the structural trend. Second, we select polynomial fitting as the nonstationary filtering method and expand the application range of the nonstationary polynomial fitting. Finally, we apply variableamplitude polynomial fitting along the direction of the dip to improve the adaptive structureoriented filtering. Model and field seismic data show that the proposed method suppresses the seismic noise while protecting structural information.
基金Pre-Research Program of General Armament Department during the11th Five-Year Plan Period (No51309020503)the National Defense Basic Research Program of China (973Program)(No973-61334)+1 种基金the National Natural Science Foundation of China(No50575042)Specialized Research Fund for the Doctoral Program of Higher Education (No20050286026)
文摘To improve the navigation accuracy of an autonomous underwater vehicle （AUV）, a novel terrain passive integrated navigation system （TPINS） is presented. According to the characteristics of the underwater environment and AUV navigation requirements of low cost and high accuracy, a novel TPINS is designed with a configuration of the strapdown inertial navigation system （SINS）, the terrain reference navigation system （TRNS）, the Doppler velocity sonar （DVS）, the magnetic compass and the navigation computer utilizing the unscented Kalman filter （UKF） to fuse the navigation information from various navigation sensors. Linear filter equations for the extended Kalman filter （EKF）, nonlinear filter equations for the UKF and measurement equations of navigation sensors are addressed. It is indicated from the comparable simulation experiments of the EKF and the UKF that AUV navigation precision is improved substantially with the proposed sensors and the UKF when compared to the EKF. The TPINS designed with the proposed sensors and the UKF is effective in reducing AUV navigation position errors and improving the stability and precision of the AUV underwater integrated navigation.
文摘The cardiac and vascular effect of ethanolamine nitrate ester ferulate (ENF) wasinvestigated on isolated working guinea pig heart (IWH) and rat aortic ring. The coronary blood flowwas remarkably increased while the cardiac functions of IWH were not significantly altered by ENFranging from 10-8 to 10-4 mol/L. The percentages of vasorelaxation of ENF t 10 μmol/L) and nicoran-dil (NIC, 10 μmol/L) on K+ (80 mmol/L)-induced contraction in aortic rings were 72 ± 8% and17±8%, respectively. The relaxation effects of ENF and NIC on phenylephrine (PE, 5 μmol/L) in-duced contraction were in a dose-dependent manner. When vessel segments were exposed to PE withmethylene blue (MB, 10 μmol/L) or with glibenclamide (GLI, 10 pmol/L), the percentages of relaxa-tion of ENF (10 μmol/L) and NIC ( 1 0 μmol/L) were 4 1 ±11 % and 49±7% or 76± 14% and the 33±9%,respectively. The results suggested that ENF improved coronary circulation and the vasodilation of ENF was mediated bv nitrate-like action.
基金Project(20A187)supported by the Hunan Provincial Department of Education,ChinaProjects(51408216,51308209)supported by the National Natural Science Foundation of China。
文摘To keep the tunnel face stable is very important for tunnel construction.In this paper,the tunnel face stability under the advanced pipe was analyzed using the Winkler foundation model and rigid limit equilibrium.The tunnel face deformation characteristics were also analyzed using the numerical simulation.The influence of parameters on the deflection of the pipe roof and the stability of the tunnel face were discussed.The results show that the tunnel face stability can be improved through increasing the pipe diameter,decreasing the initial displacement at the beginning of the pipe seat,and adopting the short round length and small excavation height.With the increase of tunnel burial depth,the safety factor of tunnel face stability first decreases,then increases,and then remains unchanged.The deformation at the center of the tunnel face is larger than the deformation at the surround sides and at the corner.The horizontal displacement varies little with the increasing of the pipe length.The horizontal displacement at the center of the tunnel face increases with the increase of the pipe ring spacing and the pipe longitudinal spacing.There is an optimum external angle.
文摘Morpho-tectonic study plays an important role in deciphering the effects of tectonic activity in the geomorphic evolution of the drainage basins.Romushi watershed forms one of the major watersheds of the intermontane Karewa Basin of Kashmir Valley.The Karewa sediments are characterized by glacio-fluvio-lacustrine deposits capped by the aeolian loess.The geomorphic,morphometric and lithostratigraphic studies of these cap deposits have been carried out to elucidate the effect of tectonics on the geomorphic evolution of Romushi Watershed.Geomorphic mapping was carried out using GPS measurements,DEM at 30m resolution,Topographic Position Index(TPI) model,topographic maps,LANDSAT TM Imagery and field data.Morphometric and morphotectonic analyses in GIS environment were used to calculate various geomorphic indices(Mountain Front Sinuosity Index,Bifurcation Ratio,Asymmetry Factor,River Profile,etc).These indices reveal that the tectonic uplift observed in the region due to Himalayan orogeny coupled with mass movement and aeolian deposition have dominated the landscape evolution of intermontane Karewa Basin of Kashmir throughout the Late Quaternary Period.Additional data from lithostratigraphic measurements were analyzed to understand the geomorphic evolution of intermontane Karewa Basin.The data revealed that the basin has experienced differential uplift and erosion rates from time to time in the geological past.This was corroborated by the results from the morphometric and morphotectonic analysis.
基金supported by Projects of Natural Science Foundation of China (Grant No. NSFC41371282)the Strategic Priority Research Program–Climate Change: Carbon Budget and Related Issues of the Chinese Academy of Sciences (CAS) (Grant No. XDA05050403)+1 种基金"100-Talents Program" of CAS, the Action Plan for West Development Project ofCAS (KZCX2-XB3-13)funds of State Key Laboratory of Loess and Quaternary Geology,Institute of Earth Environment of CAS (Grant No. SKLLQG1123)
文摘Are there some relationships among species diversity and soil chemical properties of high altitude natural grasslands? Plant community composition and chemical properties of soil samples were compared to investigate the relationship between soil and species diversity, and the richness in Tibetan alpine grasslands. Results showed that species diversity was significantly positively related to soil organic matter(SOM), total nitrogen(TN),available nitrogen(AN), total phosphorus(TP),available phosphorus(AP), and available potassium(AK) in the high alpine grasslands. Margalef's species richness index was also significantly positively related to SOM, TN, AN, and TP. Most soil chemical properties showed significantly positive correlation with species diversity and Margalef's richness index.Our results suggested that higher plant species richness index and diversity occurred in more fertile soil habitats in high altitude natural grassland community. In practice, fertilization management for the restoration of degraded grassland should be conducted with reference to the nutrient levels ofnatural grassland without the additional artificial fertilizer and with higher species-diversity and richness index.
基金Projects(41173055,41772118)supported by the National Natural Science Foundation of China
文摘Based on the element geochemistry and biomarkers of the oil shale from the Chang 7 sub-unit in the southern Ordos Basin,the depositional conditions and organic source of the oil shale are discussed.Biomarkers analyses show that the oil shale has a homologous organic matter source,with a mix of plankton and advanced plants.U/Th and V/Ni ratios suggest that the redox condition is dominated by a reducing condition,and the degree of anoxia in the Tongchuan area is higher than that of the Xunyi area.Sr/Ba ratios illustrate that the oil shale is deposited in fresh water and the paleosalinity in the Tongchuan area is slightly higher.Fe/Ti ratios imply that the Tongchuan area underwent obvious hydrothermal fluid activities.Sr/Cu ratios show warm and humid paleoclimate in both areas.As assessed by(La/Yb)NASC,the deposition rate in the Tongchuan area is relatively lower.Fe/Co and Th/U ratios suggest that the paleo-water-depth in the Tongchuan area is deeper.The source rock could have the advance plants source,which must have close relationship with the Qinling orogeny.Comparing the paleoenvironment,the Tongchuan area has better depositional conditions,and is the key oil shale exploration area in the southern Ordos Basin.
基金supported by the National Basic Research Program of China(973 Program)(No.2013CB228603)National Science and Technology major projects(No.2011ZX05024 and 2011ZX05010)the National Natural Science Foundation of China(No.41174119)
文摘Seismic inversion is a highly ill-posed problem, due to many factors such as the limited seismic frequency bandwidth and inappropriate forward modeling. To obtain a unique solution, some smoothing constraints, e.g., the Tikhonov regularization are usually applied. The Tikhonov method can maintain a global smooth solution, but cause a fuzzy structure edge. In this paper we use Huber-Markov random-field edge protection method in the procedure of inverting three parameters, P-velocity, S-velocity and density. The method can avoid blurring the structure edge and resist noise. For the parameter to be inverted, the Huber- Markov random-field constructs a neighborhood system, which further acts as the vertical and lateral constraints. We use a quadratic Huber edge penalty function within the layer to suppress noise and a linear one on the edges to avoid a fuzzy result. The effectiveness of our method is proved by inverting the synthetic data without and with noises. The relationship between the adopted constraints and the inversion results is analyzed as well.
文摘The basic granulite of the Altay orogenic belt occurs as tectonic lens in the Devonian medium- to lower-grade metamorphic beds through fault contact. The Altay granulite (AG) is an amphibole plagioclase two-pyroxene granulite and is mainly composed of two pyroxenes, plagioclase, amphibole and biotite. Its melano-minerals are rich in Mg/(Mg+Fe2+), and its amphibole and biotite are rich in TiO2. The AG is rich in Mg/(Mg+Fe2+), Al2O3 and depletion of U, Th and Rb contents. The AG has moderate ∑REE and LREE-enriched with weak positive Eu anomaly. The AG shows island-arc pattern with negative Nb, P and Ti anomalies, reflecting that formation of the AG may be associated with subduction. Geochemical and mineral composition data reflect that the protolith of the AG is calc-alkaline basalt and formed by granulite facies metamorphism having peak P-T conditions of 750 °C?780 °C and 0.6?0.7 Gpa. The AG formation underwent two stages was suggested. In the early stage of oceanic crustal subduction, calc-alkaline basalt with island-arc environment underwent granulite facies metamorphism to form the AG in deep crust, and in the late stage, the AG was thrust into the upper crust.
基金supported by the National Natural Science Foundation of China (50879085)the Program for New Century Excellent Talents in University(NCET-07-0778)the Key Technology Research Project of Dynamic Environmental Flume for Ocean Monitoring Facilities (201005027-4)
文摘Compared with traditional real-time forecasting,this paper proposes a Grey Markov Model(GMM) to forecast the maximum water levels at hydrological stations in the estuary area.The GMM combines the Grey System and Markov theory into a higher precision model.The GMM takes advantage of the Grey System to predict the trend values and uses the Markov theory to forecast fluctuation values,and thus gives forecast results involving two aspects of information.The procedure for forecasting annul maximum water levels with the GMM contains five main steps:1) establish the GM(1,1) model based on the data series;2) estimate the trend values;3) establish a Markov Model based on relative error series;4) modify the relative errors caused in step 2,and then obtain the relative errors of the second order estimation;5) compare the results with measured data and estimate the accuracy.The historical water level records(from 1960 to 1992) at Yuqiao Hydrological Station in the estuary area of the Haihe River near Tianjin,China are utilized to calibrate and verify the proposed model according to the above steps.Every 25 years' data are regarded as a hydro-sequence.Eight groups of simulated results show reasonable agreement between the predicted values and the measured data.The GMM is also applied to the 10 other hydrological stations in the same estuary.The forecast results for all of the hydrological stations are good or acceptable.The feasibility and effectiveness of this new forecasting model have been proved in this paper.
文摘Meromictic soda and saline lakes are unique ecosystems characterized by the stability of physical,chemical and biological parameters,and they are distributed all over the world.Lakes located in regions with average annual negative air temperature are of particular interest because of the presence of two periods with intensive and dynamic processes:the so-called biological summer and the long ice season with the biological spring.Soda Lake Doroninskoe is located in Eastern Transbaikalia(51°14′N,112°14′E) in the permafrost zone in an extreme continental climate,and is covered by ice for seven months per year.The structure and diversity of the microbial communities throughout the water column of the lake was studied by 16 S r RNA gene amplicon metasequencing.Different species with specific functions were found to dominate at different depths.Metabolically flexible bacteria with a capacity to switch between anoxygenic photosynthesis and aerobic chemotrophic metabolism dominate in soda Lake Doroninskoe.
基金supported by the Natural Science Foundation of China(Grant No.41371120)the Koshi Basin Programme(Support from the Australian Government through the Department of Foreign Affairs and Trade(DFAT))the Chinese Academy of Sciences-The World Academy of Sciences(CAS-TWAS)President’s Fellowship Programme for international PhD students
文摘Land use and land cover(LULC) in Nepal has undergone constant change over the past few decades due to major changes caused by anthropogenic and natural factors and their impacts on the national and regional environment and climate.This comprehensive review of past and present studies of land use and land cover change(LUCC) in Nepal concentrates on cropland, grassland, forest, snow/glacier cover and urban areas. While most small area studies have gathered data from different sources and research over a short period, across large areas most historical studies have been based on aerial photographs such as the Land Resource Mapping Project in 1986. The recent trend in studies in Nepal is to focus on new concepts and techniques to analyze LULC status on the basis of satellite imagery, with the help of geographic information system and remote sensing tools. Studies based on historical documents, and historical and recent spatial data on LULC, have clearly shown an increase in cropland areas in Nepal,and present results indicating different rates and magnitudes. A decrease in forest and snow/glacier coverage is reported in most studies. Little information is available on grassland and urban areas from past research. The unprecedented rate of urbanization in Nepal has led to significant urban land changes over the past 30 years. Meanwhile, long term historical LUCC research in Nepal is required for extensive work on spatially explicit reconstructions on the basis of historical and primary data collection, including LULC archives and drivers for future change.
文摘For thin gas reservoir of low-porosity and low-permeability in the loess desert area, a suite of lateral reservoir prediction techniques has been developed by Changqing Oil Company and the excellent effects achieved in exploration and exploitation in the areas such as Yulin, Wushenqi,Suligemiao, Shenmu etc., so that the Upper Paleozoic gas reserve has been stably increasing for eight years in Changqing Oilfield. The paper analyzed the effects and experience of the application of these techniques in detail.
文摘A coal burst occurred on 15 April, 2014 at the Austar Coal Mine, located west of Newcastle, NSW,Australia. The burst resulted in fatal injuries to two men working as part of the mining crew at the development face. At the time, a continuous miner was being used to mine a longwall development gate road through heavily structured coal, at a depth of approximately 550 m. A number of pre-cursor bumps had occurred on previous shifts, emanating from the coal ribs of the roadway, in proximity to the coal face.This paper reviews the geological, geotechnical and mining conditions and circumstances leading up to the coal burst event; and presents and discusses the available evidence and possible interpretations relating to the geomechanical behaviour mechanisms that may have been critical factors in this incident. The paper also discusses some key technical and operational considerations of ground support systems and mining practices and strategies needed for operating in such conditions in the future.
基金Under the auspices of Major State Basic Research Development Program of China (No. 2010CB950900)Technology Innovation Program of Harbin City (No. 2007RFXXS029)
文摘Based on sounding data from 1975 to 2005 and TM/ETM+ remote sensing images in 1989, 2001 and 2007, the climate changes in Harbin City, Northeast China in recent 30 years were analyzed and forecasted. Results show that in the lower troposphere the meridional wind speed and mean annual wind speed decrease, and in the lower stratosphere the temperature decreases while the meridional wind speed increases significantly. In the study area, the climate is becoming warmer and wetter in the middle lower troposphere. The expansion of urban area has great effects on the surface air temperature and the wind speed, leading to the increase of the surface air temperature, the decrease of the surface wind speed, and the increase of the area of urban high temperature zone. The quantitative equations have been established among the surface air temperature, the carbon dioxide (CO2) concentration and the specific humidity (the water vapor content). It is predicted that the future increasing rate of the surface air temperature is 0.85℃/10yr if emission concentration of CO2 remains unchanged; if emission concentration of CO2 decreases to 75%, 50% and 25%, respectively, the surface air temperature will increase 0.65℃/10yr, 0.46℃/10yr and 0.27℃/10yr, respectively. The rise of the surface air temperature in the study area is higher than that of the global mean temperature forecasted by IPCC.
