常用尼龙阻沙网的孔隙度为均匀分布,而风沙流结构在垂直方向上是非均匀分布的。通过设计4种孔隙度非均匀分布的尼龙阻沙网:大条带上疏下密式(A)、大条带上密下疏式(B)、小条带疏密相间式(C),将其布设在塔克拉玛干沙漠腹地的垄间平地,以...常用尼龙阻沙网的孔隙度为均匀分布,而风沙流结构在垂直方向上是非均匀分布的。通过设计4种孔隙度非均匀分布的尼龙阻沙网:大条带上疏下密式(A)、大条带上密下疏式(B)、小条带疏密相间式(C),将其布设在塔克拉玛干沙漠腹地的垄间平地,以均匀结构阻沙网为对照(CK)。对4种阻沙网前后的风速变化、防风效能、积沙形态、积沙量进行对比。结果表明:①B阻沙网有效防护距离最短,仅为6H(H为阻沙网的高度),其余3种结构有效防护距离差别不大,均为15H;在网后10H处0.15 m、0.3 m和0.5 m 3个观测高度,风速削弱程度的平均值存在明显差异,呈C>A>B>CK。②在风季后期,4种结构阻沙网前后积沙量B最小,其余3种类型差别不大。③综合考虑防风和阻沙效益,C阻沙网提供了一个较好的结构模式,防护效益最好,B阻沙网最差,A和CK阻沙网效益相差不大。研究结果为高立式沙障结构优化设计提供了参考依据。展开更多
An effort was made to couple FVCOM (a three-dimensional (3D),unstructured grid,Finite Volume Coastal Ocean Model) and FVCOM-SWAVE (an unstructured grid,finite-volume surface wave model) for the study of nearshore ocea...An effort was made to couple FVCOM (a three-dimensional (3D),unstructured grid,Finite Volume Coastal Ocean Model) and FVCOM-SWAVE (an unstructured grid,finite-volume surface wave model) for the study of nearshore ocean processes such as tides,circulation,storm surge,waves,sediment transport,and morphological evolution.The coupling between FVCOM and FVCOM-SWAVE was achieved through incorporating 3D radiation stress,wave-current-sediment-related bottom boundary layer,sea surface stress parameterizations,and morphology process.FVCOM also includes a 3D sediment transport module.With accurate fitting of irregular coastlines,the model provides a unique tool to study sediment dynamics in coastal ocean,estuaries,and wetlands where local geometries are characterized by inlets,islands,and intertidal marsh zones.The model was validated by two standard benchmark tests: 1) spectral waves approaching a mild sloping beach and 2) morphological changes of seabed in an idealized tidal inlet.In Test 1,model results were compared with both analytical solutions and laboratory experiments.A further comparison was also made with the structured grid Regional Ocean Model System (ROMS),which provides an insight into the performance of the two models with the same open boundary forcing.展开更多
Estonian Forestry Development Programme set in 2003 ambitious goal that area of strictly protected forests should increase at least to 10% from total forest area in Estonia before 2010 by expanding the area of old-gro...Estonian Forestry Development Programme set in 2003 ambitious goal that area of strictly protected forests should increase at least to 10% from total forest area in Estonia before 2010 by expanding the area of old-growth under protection, improving the representativeness of conservation areas and establishment of large conservation sites. Inventory of forests was carried out on existing and possible new conservation areas within the Estonian Forest Conservation Area Network project (EFCAN) in 1999-2001. EFCAN project had remarkable results. The share of strictly protected forests has increased to 7.8% of total forest area by 2009 and the network of conservation areas is quite well covering all forest ecosystems in Estonia. Several selected areas are still not protected for different reasons. These areas should still be considered for protection as the areas may lose their conservation value. Several forest types (meso-eutrophic, eutrophic boreo-nemoral and eutrophic paludifying forests) should have larger area for conservation and large disturbance areas (wind damage, forest fire) should be also included into the network.展开更多
This paper presents results of a pilot research conducted among social networks of both Sudanese and Egyptians in Jeddah city, Saudi Arabia (SA). The main objectives of the research are focused into four interrelate...This paper presents results of a pilot research conducted among social networks of both Sudanese and Egyptians in Jeddah city, Saudi Arabia (SA). The main objectives of the research are focused into four interrelated issues: (1) to analyse the structural-function of the social networks of Sudanese and Egyptian migrants; (2) to explain the opportunities and challenges confronting the social networks; (3) to examine the elements of implications on SA society as perceived by the networks; and (4) to identify perceived future visions of the social network members in the context of their social and economic remittances in both countries. The research has applied a qualitative method and a structured interview sheet was used for data collection. The Sudanese sample focused on members from a Nubian social network in ]eddah who resemble skilled, semi-skilled, and unskilled labours, while the Egyptian sample selected randomly from semi-skilled youth labours and unskilled labours as informal groups. The research has found some differences in the structural functions of both groups. There are many similarities shared between the two groups in relation to conserving social ties, support and cooperation as one homogeneous socio-ethnic groups in the hosting country. Also, the results show that both groups follow similar strategies of social and economic remittances to home land. Moreover, both groups are suffering and facing many shared challenges regarding economic security and sustainability in the hosting country. While, the Sudanese group has clear vision in respect of the betterment of the migrants in SA, the Egyptian group perceives the future as gloomy and uncertain.展开更多
According to the construction project of the crustal deformation mobile monitoring network in the cascade hydropower stations built in the lower reaches of Jinsha River,this paper analyzes the design ideas and layout ...According to the construction project of the crustal deformation mobile monitoring network in the cascade hydropower stations built in the lower reaches of Jinsha River,this paper analyzes the design ideas and layout principles of crustal deformation mobile monitoring used in the monitoring of reservoir induced earthquakes. This paper introduces three types of monitoring networks used in the Xiluodu reservoir and Xiangjiaba reservoir, as well as the work already undertaken,in order to provide a kind of reference for the related engineering construction and comprehensive monitoring of reservoir induced earthquakes.展开更多
A groundwater observational network for monitoring seismic precursors has been established at the reservoirs on the lower reaches of the Jinsha River in southwestern China, where a series of hydropower stations are un...A groundwater observational network for monitoring seismic precursors has been established at the reservoirs on the lower reaches of the Jinsha River in southwestern China, where a series of hydropower stations are under construction. It is the second network in China that is operated by enterprises with the purpose to observe and study earthquake precursors in reservoir areas. This paper presents the layout and technical constitution of the network, features of its observational wells and aquifers and the preliminary result of its experimental operation. Its capability to monitor seismic precursor is evaluated based on an analysis of the well-aquifer system as well as the multiple-monthly, monthly, daily and hourly variations of water levels and water temperatures observed by this network.展开更多
Fine measurements have been conducted to temperatures and their gradients of six wells of the Jinsha River Groundwater Observational Network.The results show that the influence depths of sun radiation heat are 50m to ...Fine measurements have been conducted to temperatures and their gradients of six wells of the Jinsha River Groundwater Observational Network.The results show that the influence depths of sun radiation heat are 50m to 125m,average temperature gradients in the wells range from 0.11 to 2.81℃/hm and most are 1~2℃/hm,and the temperature gradients on varied depth sections of one well are highly changeable.Lithology of strata and their integrity,particularly high-angle crashed fault zones,have imposed major effects on the influence depths of sun radiation heat and temperature gradients of the wells.The micro dynamic characteristics of water temperature,such as coseismic effects,tidal effects and anomalies of the wells prior to earthquakes,probably depend,to a large degree,on the temperature gradients of the depths at which the water temperature sensors are settled.展开更多
Even though Saudi Arabia is the world's largest producer and exporter of petroleum and petroleum based products, it is also blessed with high potential of renewable energy sources like solar and wind. Untapped wind a...Even though Saudi Arabia is the world's largest producer and exporter of petroleum and petroleum based products, it is also blessed with high potential of renewable energy sources like solar and wind. Untapped wind and solar energy sources, which are abundant throughout the kingdom, can be connected and optimally integrated into the grid through the use of smart grid technologies and the expansion of transmission facilities. Smart grid is an auto-balancing, self-monitoring power grid that accepts power from any source of fuel like oil, sun or wind and delivers electricity from suppliers to consumers. It helps to control the use of appliances in order to save energy, reduces cost and increase reliability. This paper describes the attributes of a smart grid and how these act as driving force to modernize the electrical power grid. The necessity of conservation of oil in Saudi Arabia is argued. Moreover, the vast availability of renewable energy sources like solar and wind in Saudi Arabia and advantages in utilizing these sources through smart grid technologies are advocated in this paper.展开更多
文摘常用尼龙阻沙网的孔隙度为均匀分布,而风沙流结构在垂直方向上是非均匀分布的。通过设计4种孔隙度非均匀分布的尼龙阻沙网:大条带上疏下密式(A)、大条带上密下疏式(B)、小条带疏密相间式(C),将其布设在塔克拉玛干沙漠腹地的垄间平地,以均匀结构阻沙网为对照(CK)。对4种阻沙网前后的风速变化、防风效能、积沙形态、积沙量进行对比。结果表明:①B阻沙网有效防护距离最短,仅为6H(H为阻沙网的高度),其余3种结构有效防护距离差别不大,均为15H;在网后10H处0.15 m、0.3 m和0.5 m 3个观测高度,风速削弱程度的平均值存在明显差异,呈C>A>B>CK。②在风季后期,4种结构阻沙网前后积沙量B最小,其余3种类型差别不大。③综合考虑防风和阻沙效益,C阻沙网提供了一个较好的结构模式,防护效益最好,B阻沙网最差,A和CK阻沙网效益相差不大。研究结果为高立式沙障结构优化设计提供了参考依据。
基金supported by the State Scholarship Fund for his PhD degree during a two-year (2007-2009) study at University of Massachusetts-Dartmouth in US
文摘An effort was made to couple FVCOM (a three-dimensional (3D),unstructured grid,Finite Volume Coastal Ocean Model) and FVCOM-SWAVE (an unstructured grid,finite-volume surface wave model) for the study of nearshore ocean processes such as tides,circulation,storm surge,waves,sediment transport,and morphological evolution.The coupling between FVCOM and FVCOM-SWAVE was achieved through incorporating 3D radiation stress,wave-current-sediment-related bottom boundary layer,sea surface stress parameterizations,and morphology process.FVCOM also includes a 3D sediment transport module.With accurate fitting of irregular coastlines,the model provides a unique tool to study sediment dynamics in coastal ocean,estuaries,and wetlands where local geometries are characterized by inlets,islands,and intertidal marsh zones.The model was validated by two standard benchmark tests: 1) spectral waves approaching a mild sloping beach and 2) morphological changes of seabed in an idealized tidal inlet.In Test 1,model results were compared with both analytical solutions and laboratory experiments.A further comparison was also made with the structured grid Regional Ocean Model System (ROMS),which provides an insight into the performance of the two models with the same open boundary forcing.
基金This study was supported by the Estonian Science Foundation and the Estonian Ministry of Environment.
文摘Estonian Forestry Development Programme set in 2003 ambitious goal that area of strictly protected forests should increase at least to 10% from total forest area in Estonia before 2010 by expanding the area of old-growth under protection, improving the representativeness of conservation areas and establishment of large conservation sites. Inventory of forests was carried out on existing and possible new conservation areas within the Estonian Forest Conservation Area Network project (EFCAN) in 1999-2001. EFCAN project had remarkable results. The share of strictly protected forests has increased to 7.8% of total forest area by 2009 and the network of conservation areas is quite well covering all forest ecosystems in Estonia. Several selected areas are still not protected for different reasons. These areas should still be considered for protection as the areas may lose their conservation value. Several forest types (meso-eutrophic, eutrophic boreo-nemoral and eutrophic paludifying forests) should have larger area for conservation and large disturbance areas (wind damage, forest fire) should be also included into the network.
文摘This paper presents results of a pilot research conducted among social networks of both Sudanese and Egyptians in Jeddah city, Saudi Arabia (SA). The main objectives of the research are focused into four interrelated issues: (1) to analyse the structural-function of the social networks of Sudanese and Egyptian migrants; (2) to explain the opportunities and challenges confronting the social networks; (3) to examine the elements of implications on SA society as perceived by the networks; and (4) to identify perceived future visions of the social network members in the context of their social and economic remittances in both countries. The research has applied a qualitative method and a structured interview sheet was used for data collection. The Sudanese sample focused on members from a Nubian social network in ]eddah who resemble skilled, semi-skilled, and unskilled labours, while the Egyptian sample selected randomly from semi-skilled youth labours and unskilled labours as informal groups. The research has found some differences in the structural functions of both groups. There are many similarities shared between the two groups in relation to conserving social ties, support and cooperation as one homogeneous socio-ethnic groups in the hosting country. Also, the results show that both groups follow similar strategies of social and economic remittances to home land. Moreover, both groups are suffering and facing many shared challenges regarding economic security and sustainability in the hosting country. While, the Sudanese group has clear vision in respect of the betterment of the migrants in SA, the Egyptian group perceives the future as gloomy and uncertain.
基金sponsored by the Key Construction Program of the Three Gorges Project,China
文摘According to the construction project of the crustal deformation mobile monitoring network in the cascade hydropower stations built in the lower reaches of Jinsha River,this paper analyzes the design ideas and layout principles of crustal deformation mobile monitoring used in the monitoring of reservoir induced earthquakes. This paper introduces three types of monitoring networks used in the Xiluodu reservoir and Xiangjiaba reservoir, as well as the work already undertaken,in order to provide a kind of reference for the related engineering construction and comprehensive monitoring of reservoir induced earthquakes.
基金sponsored by the Jinsha River Development Corporation Ltd. Program of China Three Gorges Cooperation (JSJ(06)007)
文摘A groundwater observational network for monitoring seismic precursors has been established at the reservoirs on the lower reaches of the Jinsha River in southwestern China, where a series of hydropower stations are under construction. It is the second network in China that is operated by enterprises with the purpose to observe and study earthquake precursors in reservoir areas. This paper presents the layout and technical constitution of the network, features of its observational wells and aquifers and the preliminary result of its experimental operation. Its capability to monitor seismic precursor is evaluated based on an analysis of the well-aquifer system as well as the multiple-monthly, monthly, daily and hourly variations of water levels and water temperatures observed by this network.
基金supported by the Jinsha River Development Corporation Limited,China Yangtze Three Gorge Engineering Development Group(JSJ(06)-007)
文摘Fine measurements have been conducted to temperatures and their gradients of six wells of the Jinsha River Groundwater Observational Network.The results show that the influence depths of sun radiation heat are 50m to 125m,average temperature gradients in the wells range from 0.11 to 2.81℃/hm and most are 1~2℃/hm,and the temperature gradients on varied depth sections of one well are highly changeable.Lithology of strata and their integrity,particularly high-angle crashed fault zones,have imposed major effects on the influence depths of sun radiation heat and temperature gradients of the wells.The micro dynamic characteristics of water temperature,such as coseismic effects,tidal effects and anomalies of the wells prior to earthquakes,probably depend,to a large degree,on the temperature gradients of the depths at which the water temperature sensors are settled.
文摘Even though Saudi Arabia is the world's largest producer and exporter of petroleum and petroleum based products, it is also blessed with high potential of renewable energy sources like solar and wind. Untapped wind and solar energy sources, which are abundant throughout the kingdom, can be connected and optimally integrated into the grid through the use of smart grid technologies and the expansion of transmission facilities. Smart grid is an auto-balancing, self-monitoring power grid that accepts power from any source of fuel like oil, sun or wind and delivers electricity from suppliers to consumers. It helps to control the use of appliances in order to save energy, reduces cost and increase reliability. This paper describes the attributes of a smart grid and how these act as driving force to modernize the electrical power grid. The necessity of conservation of oil in Saudi Arabia is argued. Moreover, the vast availability of renewable energy sources like solar and wind in Saudi Arabia and advantages in utilizing these sources through smart grid technologies are advocated in this paper.