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OVERVIEW OF DAM GULLY EROSION RESEARCH

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International Journal of Sediment Research 2005年第3期20卷 105-115页

作者： G. J. HANSON,D. M. TEMPLE,K. M. ROBINSON,K. R. COOK usda-ARS HERU Stillwater usda-ARS HERU Stillwater usda-nrcs ENTSC Greensboro usda-nrcs state office Stillwater

Traditionally gully erosion has been identified with the dissection of the landscape in agricultural settings but it is also recognized as a prevalent erosion feature in earthen dam auxiliary spillways and embankments. Flows through earthen spillways and over dam embankments, due to large rainfall events, have the potential to erode and breach the dam or spillway and result in catastrophic releases from the reservoir. The gully erosion process in an earthen spillway or on an embankment can be characterized by stages of initiation, development, and migration of a headcut. A headcut is defined as a near vertical drop at the upstream end of a gully. The rate of headcut migration is important in determining the breach potential of an earthen spillway and dam embankment. A research program is being conducted to examine the gully erosion processes of earthen dam auxiliary spillways and embankments. This paper describes: 1) the unique test facilities constructed to examine the dominant factors affecting the erosion of earthen spillways and embankments; 2) the observations of the erosion processes and results to date; and 3) the predictive relationships that have been developed for dam gully erosion research at the ARS Hydraulic Engineering Research Unit laboratory in Stillwater, OK.

关键词： Dams Erosion Spillways Embankments Gullies Headcut Breach

China and Africa in the New Era:A Partnership of Equals(Ⅰ)state Council Information office of the Peopled Republic of China

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Beijing Review 2021年第49期64卷 I0001-I0016页

作者：无 state Council Information office of the Peopled Republic of China

Foreword China is the largest developing country in the world,and Africa is the continent with the largest number of developing *** past experiences and similar aims and goals have brought China and Africa close *** a... 详细信息

关键词：中国对外政策命运共同体中非合作历史遭遇中国和非洲发展中国家团结合作重要基石

Geographic segregation and evidence of density-dependent changes in sex ratios in an abundant colonial waterbird

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Integrative Zoology 2014年第5期9卷 570-582页

作者： Brian S.DORR Katie C.HANSON-DORR Travis L.DeVAULT Alban GUILLAUMET Scott C.BARRAS United states Department of Agriculture Wildlife Services(USDA-WS)National Wildlife Research CenterMississippi Field StationMississippi StateMississippiUSA usda-WS National Wildlife Research CenterOhio Field StationSanduskyOhioUSA Department of Wildlife Fisheries and AquacultureMississippi State UniversityMississippi StateMississippiUSA usda-WS MoseleyVirginiaUSA University of Hawaii Office of Research/PIPESHiloHIUSA.

Demographic information,such as geographic segregation of sexes and sex ratio data,is needed to develop,model and evaluate conservation and management strategies for wildlife.A variety of physiological,behavioral and environmental factors can influence segregation of sexes and sex ratios,many of which originate with density-dependent *** from 50:50 sex ratios of double-crested cormorants(Phalacrocorax auritus)collected during control efforts in breeding and wintering areas across their eastern range of the USA were evaluated using using a Z-test as well as Stouffer’s weighted *** addition,a specifically-designed randomization test was used to evaluate density-dependent effects on primary sex ratios in cormorants from egg collections and colony nest count data over a 21-year *** collected from breeding colonies were strongly male-biased,whereas cormorants collected from feeding flocks were slightly biased toward *** were partly segregated by sex on the wintering grounds,with significantly more males found in areas with intensive channel catfish *** null hypothesis that females produced a balanced sex ratio independent of number of nesting cormorants was rejected:more male embryos were produced during rapid population growth,whereas at maximum nesting number more female embryos were *** populations stabilized,the sex ratio was more *** examination of sex ratios indicates that different management methods and locations result in sex-biased culling of ***-biased culling in cormorants could make population reduction efforts more efficient and reduce overall *** suggest further research to examine density-dependent effects on primary sex ratios documented here.

关键词： Ashmole’s halo management Phalacrocorax auritus population growth sex ratio theory

China's First Exploration of Chukchi Sea and Its Adjacent Waters in the ArcticA Study on Lead Geochemistry of Atmospheric Aerosol

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Chinese Journal Of Geochemistry 2003年第1期22卷 23-29页

作者：朱赖民陈立奇 The Third Institute of Oceanography state Ocean Administration office for Polar Exploration state Ocean Administration

The Pb concentrations of atmospheric aerosol in the Chukchi Sea of the Arctic vary within the range of 0.167- 0.962 ng/m3, with an average of 0.532 ng/m3. These concentration values are 200 times higher than the natural background values of snow samples there. Calculation of the Pb enrichment factor of aerosol indicates that the ocean- and continent-source lead account for 9.23% and 0.01%, respectively, but industrially released Pb accounts for more than 90% of the atmospheric Pb. The Pb isotopic composition of aerosol has revealed that the sources of lead from industrial lead that causes pollution include mainly the western part of North America, East Europe and the former Soviet Union. The calculation of the total fallout flux of Pb indicates that the mean value of input flux into the Chukchi Sea is 0.02 mgm -2a -1,equivalent to that of southern Pacific but slightly lower than that of northern Indian Sea and southern Atlantic. It is evidenced that the Pb input flux into the Chukchi Sea is far lower than that off the Baltic Sea, the North Sea and the Mediterranean Sea.

关键词：北极楚克海全球变化海水北极圈海洋大气气溶胶铅同位素地球化学

Train-induced vibration on elevated railway station

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Journal of Central South University 2013年第12期20卷 3745-3753页

作者：杨娜郭婷孙国忠 School of Civil Engineering Beijing Jiaotong University Patent Examination Cooperation Center of Patent office State Intellectual Property Office of P.R.China

Results of in-situ vibration measurement carried out at Tianjin West Elevated Railway Station which has the trains running on the station structure were reported. The main excitation source is the train passing through the station. Vibration measurements were recorded in the vertical direction of the supporting track beam, the platform and the steel truss beam of the waiting hall, as well as in the vertical, longitudinal and transverse directions of the roof arch base of the station. Acceleration time responses were obtained. The maximum value, vibration level and one-third octave band RMS spectra of the measured accelerations were studied. The propagation of vibration in different structural floors was discussed. The influence of train speed, distance to the vibration source and the type of train on the structural vibration were analyzed. Results show that the vibration level increases with the train speed, while it attenuates with the distance to the track. Furthermore, the vibration responses of different structural floors were compared, and it is noted that the vertical vibration of the bottom slab of the platform is most severe and the transverse vibration of the roof arch base is the smallest. The results provide reference on the vibration characteristics and vibration energy distribution of this type of "Train on building frame" system used as an elevated railway station.

关键词： elevated railway station measurement in-situ vibration propagation train-induced vibration

Plant Community Development in a Dryland CREP in Northeastern Oregon

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American Journal of Plant Sciences 2011年第6期2卷 744-752页

作者： John D. Williams Heidi M. Hartman Lori M. Spencer James O. Loiland usda Agricultural Research Service Columbia Plateau Conservation Research Center Pendleton USA Umatilla Soil & Water Conservation District Pendleton USA Department Environmental Science and Regional Planning Washington State University Tri-Cities Richland USA District Conservationist (usda-nrcs) Dillingham Field Office Dillingham USA

Riparian areas in dryland crop regions of the Intermountain Pacific Northwest have largely been converted to cropland or pasture during the last 140 years. Some formerly cultivated floodplains have become difficult to farm;enrollment of these lands into conservation programs provides the opportunity to use them as wildlife habitat and as buffer areas near streams. Our objective was to evaluate plant community development on an usda Conservation Reserve Enhan- cement Program site in northeastern Oregon from when the plant was planted in 1999 through 2008. The research was designed as a descriptive study. We established permanent line-transects to quantify vegetation establishment and changes in species composition through time. We collected data in 2000-2001 and 2007-2008. Vegetation cover in 2000-2001 was 100%, dominated by tall wheatgrass. Living plant material cover decreased from 98% in 2000-2001 to 33% in 2007 and 68% in 2008;dead plant residue significantly increased and tall wheatgrass cover decreased. Native species were present in similar percentages from 2000 to 2008, although there was a shift from target to nontarget species. The 1999 seeding can be judged a success because of the ground cover provided and the establishment of one target species, tall wheatgrass. However, the increased ratio of dead to living plant material and shift to non-target annual weed species suggests that more active management (i.e., fire, grazing, or mowing) of the tall wheatgrass stand is needed to maintain its productivity and/or a healthy mix of multiple species.

关键词： Conservation Buffers Riparian Management Weed Control Plant Community

Forest structure and woody plant species composition after a wildfire in beech forests in the north of Iran

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Journal of Forestry Research 2013年第2期24卷 255-262页

作者： Mohammad Naghi Adel Hassan Pourbabaei Ali Omidi Daniel C Dey Facultad de Department of Forestry Natural Resources Faculty University of Guilan Department of Forestry Natural Resources Office usda Forest Service Northern Research Station 202 Natural Resources Building

Beech （Fagus orientalis Lipsky） forest covers about 565,000 ha of land in Guilan province, north of Iran and forms a major carbon pool. It is an important economic, soil protection and recreation resource. We studied long-term effects of fire on the structure and composition 37 years after fire occurrence in these forests. To do this research, we selected 85 ha burned and 85 ha unburned beech forests）. The results indicated that the fire had not changed the overall uneven-aged structure, but it changed forest composition from pure stands to mixed stands that now include species such as Carpinus betulus, Acer cappadocicum and Alnus subcordata. The density of trees and regeneration was significantly increased, while the density of shrubs significantly decreased. The main reasons for increased tree regeneration were attributed to （1） reduction of litter depth, and （2） increase in available light from opening of the canopy and reduction in shrub competition. It is apparent that the forest is on a path to return to its natural state before the fire after 37 years.

关键词： fire structure composition regeneration beech forest Guilan Province

Corrosion behavior of 907 steel under thin electrolyte layers of artificial seawater

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Journal of Central South University 2015年第3期22卷 806-814页

作者：王慧萍丁少春朱娟张昭张鉴清曹楚南 Department of Chemistry Zhejiang University Scientific Research office Naval University of Engineering state Key Laboratory for Corrosion and Protection of Metals

The corrosion behavior of 907 steel under thin electrolyte layer(TEL) has been investigated by means of cathodic polarization curve measurement, electrochemical impedance spectroscopy(EIS) and scanning electron microscopy(SEM). The results show that the cathodic diffusion current density presents the variation trend of initial increase and subsequent decrease with the decrease of TEL thickness, and the maximum deposits at 58 μm. The cotangent-hyperbolic impedance(O) is rationally first introduced to study the diffusion process of the reactants through the corrosion products layer with many permeable holes. The initial corrosion rate of 907 steel under different TEL thickness increases with the decrease of TEL thickness except that of 104 μm,whereas the corrosion rate after long time corrosion can be ranked as 104 μm﹥402 μm﹥198 μm﹥301 μm﹥bulk solution.

关键词： 907 steel atmospheric corrosion electrochemical impedance spectroscopy polarization

Modes of Shale-Gas Enrichment Controlled by Tectonic Evolution

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Acta Geologica Sinica(English Edition) 2018年第5期92卷 1934-1947页

作者： LI Chaochun OU Chenghua state-Owned Asset Management office Southwest Petroleum University state Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum University

The typical characteristics of shale gas and the enrichment differences show that some shale gases are insufficiently explained by the existing continuous enrichment mode. These shale gases include the Wufeng–Longmaxi shale gas in the Jiaoshiba and Youyang Blocks, the Lewis shale gas in the San Juan Basin. Further analysis reveals three static subsystems（hydrocarbon source rock, gas reservoirs and seal formations） and four dynamic subsystems（tectonic evolution, sedimentary sequence, diagenetic evolution and hydrocarbon-generation history） in shale-gas enrichment systems. Tectonic evolution drives the dynamic operation of the whole shale-gas enrichment system. The shale-gas enrichment modes controlled by tectonic evolution are classifiable into three groups and six subgroups. Group I modes are characterized by tectonically controlled hydrocarbon source rock, and include continuous in-situ biogenic shale gas（Ⅰ_1） and continuous in-situ thermogenic shale gas（Ⅰ_2）. Group Ⅱ modes are characterized by tectonically controlled gas reservoirs, and include anticline-controlled reservoir enrichment（Ⅱ_1） and fracture-controlled reservoir enrichment（Ⅱ_2）. Group Ⅲ modes possess tectonically controlled seal formations, and include faulted leakage enrichment（Ⅲ_1） and eroded residual enrichment（Ⅲ_2）. In terms of quantity and exploitation potential, Ⅰ_1 and Ⅰ_2 are the best shale-gas enrichment modes, followed by Ⅱ_1 and Ⅱ_2. The least effective modes are Ⅲ_1 and Ⅲ_2. The categorization provides a different perspective for deep shale-gas exploration.

关键词： shale gas enrichment mode tectonic evolution hydrocarbon source gas reservoir seal formation