With the commissioning of Phase$,the port of Kribi is emerging as an important maritime transport hub in Central Africa With a 715-metre quay and a draught of 16 metres,the Autonomous Port of Kribi(APK)stands as one o...With the commissioning of Phase$,the port of Kribi is emerging as an important maritime transport hub in Central Africa With a 715-metre quay and a draught of 16 metres,the Autonomous Port of Kribi(APK)stands as one of Africa’s most strategically significant deep-water ports.Situated on Cameroon’s Atlantic coast,it o!ers direct access to international shipping lanes and is designed to handle large-capacity vessels that many regional ports cannot accommodate.展开更多
The lower member of Dalazi Formation is an important oil reservoir in the Songjiang Basin.Based on the research on its field-measured geological profiles,lithological combination characteristics and grain size distrib...The lower member of Dalazi Formation is an important oil reservoir in the Songjiang Basin.Based on the research on its field-measured geological profiles,lithological combination characteristics and grain size distribution characteristics,combined with the analysis of the spatial distribution characteristics,sedimentary structural characteristics and hydrodynamic conditions of the sediments in this member,nine sedimentary microfacies of the fan delta plain subfacies,fan delta front subfacies and littoral-shallow lacustrine subfacies have been identified.The study reveals that lower member of Dalazi Formation in the research area follows a fan delta–shallow lacustrine depositional model in the steep slope zone of a rift lake basin.The sediments primarily originate from the Pre-Mesozoic strata in the steep southeastern and eastern margins.The basin center migrated from the early Xiaoshahe area to the Yangmucun–Shenglicun area,and the sedimentary system gradually transitioned from fan delta to littoral-shallow lacustrine facies.展开更多
The integration of oscillating water columns(OWCs)with piles to create a dual-function OWC-pile breakwater presents an innovative approach for harbor construction and coastline protection while enabling wave energy ut...The integration of oscillating water columns(OWCs)with piles to create a dual-function OWC-pile breakwater presents an innovative approach for harbor construction and coastline protection while enabling wave energy utilization.Local scour significantly impacts foundation safety and is crucial for structural design.This study examines wave-induced local scour at a dual-function OWC-pile breakwater through experimental methods.A high-resolution laser scanner tracked the development of 3D local scour profiles at various time intervals under regular wave conditions.The analysis focused on key parameters including scour-hole development time scale,dimensions,reflection and transmission coefficients,and energy extraction efficiency during scour evolution.The integration of OWCs substantially increased the equilibrium scour depth compared to conventional pile breakwaters,potentially affecting foundation stability.The scour profile development showed minimal impact on wave energy conversion efficiency.Wave transmission and reflection remained largely unaffected by scour holes,as verified through a semi-theoretical wave scattering model for pile breakwaters.An existing time-scale formula for predicting scour depth onset in isolated circular piles under current action demonstrated reasonable accuracy in this application.The study examines the mechanisms behind increased equilibrium scour depth due to OWCs and proposes design recommendations to mitigate scour-hole depth increases.展开更多
在菲律宾薄荷岛,Panglao Shores的南棕榈度假村将艺术性、可持续性与自然景致巧妙融合,呈现一种特殊的建筑体验。由Enter Pojects Ar sia设计的这一公共空间项目,造价200万美元,不仅追求奢华,更强调生态责任、有机形态以及与海岸景观的...在菲律宾薄荷岛,Panglao Shores的南棕榈度假村将艺术性、可持续性与自然景致巧妙融合,呈现一种特殊的建筑体验。由Enter Pojects Ar sia设计的这一公共空间项目,造价200万美元,不仅追求奢华,更强调生态责任、有机形态以及与海岸景观的对话。设计师的愿景是重新定义酒店建筑,使其成为周围环境的自然延展。旅程从入口开始,流畅的曲线取代了传统的直线。以藤条构筑的雕塑感门户,交织着手工艺的温暖与结构的力量,为后续空间奠定基调。展开更多
There are many uncertain factors in the implementation of mining engineering. In order to guarantee the safety of mining workers' lives and property and improve the efficiency of coal mining, tunneling and support...There are many uncertain factors in the implementation of mining engineering. In order to guarantee the safety of mining workers' lives and property and improve the efficiency of coal mining, tunneling and supporting technology should be adopted to reduce the influence of various unfavorable factors. For example, the U-shaped steel shed support and 11805 return air lane are replaced by anchor net and cable support. The 230802 haulage lane and 230802 return air lane of Zude Coal Mine in Yunnan Dongyuan Hengding Coal Industry Co., Ltd. have changed from the original U-shaped steel shed support to the anchor net and cable support. The haulage up the hill in the second mining area of Hexing Coal Mine and the heading method of 11805 return air lane have changed from the original blasting heading to the EBZ180 heading machine heading, which not only speeds up the construction progress of the roadway but also reduces the labor intensity. Therefore, the relevant staff must combine the actual situation of the coal mining area, select the corresponding excavation and support technology, at the same time, should also strictly implement the operation procedures and safety technical measures, only in this way can the comprehensive benefit of the coal mining work be fully guaranteed.展开更多
The wide-shallow composite bucket foundation(WSCBF) is a new type of offshore wind power foundation that can be built on land and rapidly installed offshore, there by effectively reducing the construction time and cos...The wide-shallow composite bucket foundation(WSCBF) is a new type of offshore wind power foundation that can be built on land and rapidly installed offshore, there by effectively reducing the construction time and costs of offshore wind power foundation. In this study, the horizontal bearing capacity is calculated by finite element simulation and compared with test results to verify the validity of results. In this process, the vertical load and bending load are respectively calculated by the finite element simulation. Under the vertical load effect, the bucket foundation and the soil inside are regarded as a whole, and the corresponding buckling failure mode is obtained. The ultimate vertical bearing capacity is calculated using empirical and theoretical formulas; the theoretical formula is also revised by finite element results. Under bending load, the rotational center of the composite bucket foundation(in a region close to the bucket bottom) gradually moves from the left of the central axis(reverse to loading direction) to the nearby compartment boards along the loading direction. The H–M envelope line shows a linear relationship, and it is determined that the vertical and bending ultimate bearing capacities can be improved by an appropriate vertical load.展开更多
Littoral-cell angioma(LCA), a primary angioma which clinically belongs to splenic hemangioma, can be mostly found in normal spleen red sinus shore cells of reticuloendothelial cell system. The cells of LCA strongly ex...Littoral-cell angioma(LCA), a primary angioma which clinically belongs to splenic hemangioma, can be mostly found in normal spleen red sinus shore cells of reticuloendothelial cell system. The cells of LCA strongly express endothelial and tissue cell associated antigens that indicate a dual differentiation characteristic; whereas only endothelial cell markers are positive in normal spleen red sinus shore cells. Diagnosis of LCA relies on histopathology. Regular follow-up is needed to monitor recurrence and metastasis.展开更多
The dynamic responses of offshore fixed platforms under ice loads are analysed in this paper. The responses calculated include the displacement and the hot spot stresses on the basis of a dynamic equation of ice-induc...The dynamic responses of offshore fixed platforms under ice loads are analysed in this paper. The responses calculated include the displacement and the hot spot stresses on the basis of a dynamic equation of ice-induced forced vibration for offshore structures. The results obtained can be cited and used for the design and operation of offshore fixed platforms against ice loading.展开更多
This study on the distribution features of petroleum hydrocarbon in water and sediment off the Fujian shore using data obtained from the baseline research on oceanic contamination in Fujian showed that: during the res...This study on the distribution features of petroleum hydrocarbon in water and sediment off the Fujian shore using data obtained from the baseline research on oceanic contamination in Fujian showed that: during the research period, petroleum hydrocarbon concentrations in water varied from 5.77 μg/L to 37.28 μg/L, averaged 14.48 μg/L; was lower in the wet season than in the dry season; and was highest in the Minjiang Estuary and Jiulong Estuary in both seasons. The petroleum hydrocarbon concentrations in shore sediment varied from 14.48 mg/kg to 784.36 mg/kg, averaged 133.3 mg/kg, and was closely related to sediment types (granularity).展开更多
Coastal erosion phenomena in China have become increasingly evident since the end of the 1950s, and the process of coastal erosion has been speeding up simce the end of the 1970s. Almostall the coastal types, the roc...Coastal erosion phenomena in China have become increasingly evident since the end of the 1950s, and the process of coastal erosion has been speeding up simce the end of the 1970s. Almostall the coastal types, the rock coasts, the muddy coastS, the sandy coasts, the coral coasts, ets. on 32,000-km iong coastline of China are in danger of erosion, especially the beaches in open coasts and the coasts of abandoned river deltas. Although coastal erosion phenomena are extensively distributed in China, the nit6nsities of erosional processes in different regions are quite different. There are various causes of coastal erosion in China, and different factors often concurred in the coastal erosional processes. The main causes for coastal erosion are sand exploitation on shores and the decrease in river sediment discharged. Coastal erosion process has endangered the houses, roads, engineering works and tourism resources in the coastal zones.展开更多
The entire Great Lakes watershed drains through Lake Ontario and flows into the St. Lawrence River near Cape Vincent, New York. The St. Lawrence River then flows northeast through Quebec and Ontario and into the large...The entire Great Lakes watershed drains through Lake Ontario and flows into the St. Lawrence River near Cape Vincent, New York. The St. Lawrence River then flows northeast through Quebec and Ontario and into the largest estuary in the world, the Gulf of Saint Lawrence. The St. Lawrence River, between Ontario, Canada and New York, United States is part of the international boundary. The St. Lawrence Seaway permits ocean-going vessels to go from the Great Lakes of North America to the Atlantic Ocean. Navigation of the St. Lawrence was not possible until canals were built around the Lachine Rapids near Montreal. The canals allowed ships to by-passes the rapids and travel into Lake Ontario. In 1954, the United States agreed to joint development of the international sections of the St. Lawrence River. The St. Lawrence Seaway was opened in 1959 and permits ocean-going ships to go all the way to the southwest corner of Lake Superior near Duluth, Minnesota. During WWII, German U-boats sank several merchant marine ships and three Canadian warships in the lower St. Lawrence River, the Strait of Belle Isle, Cabot Strait and the Gulf of Saint Lawrence. The bottom of the St. Lawrence River is littered with the wreckage of these ships and other ships which were lost during storms. The International Joint Commission recommended that the Canada and United States jointly improve navigation on the St. Lawrence River from Lake Ontario to Montreal. This lead to the signing of the St. Lawrence Treaty. Steel companies supported the treaties since the new St. Lawrence Seaway could get Labrador iron ore to the United States mills in the Great Lakes region. The Seaway’s power dams generate 3.5 million kilowatts of electricity which is provided to industry and to thousands of consumers in the New York State, New England and parts of Canada. The electric power generated by the project would be shared equally. This paper highlights how the geological and landscape properties of the St. Lawrence River watershed were responsible for the successful economic development of this important and historically-rich region of North America. Planned economic and urban development of the St. Lawrence River basin by USACE was blocked by the “Save the River” campaign. Environmental challenges include disposal of treated and untreated wastewater, water pollution, and shore erosion, invasive species and flooding.展开更多
In the paper, the sea is divided into two layers with density jumping, assuming that the physical parameters in each layer are independent of depth. Two-layer flow field with tide and wind currents is calculated with ...In the paper, the sea is divided into two layers with density jumping, assuming that the physical parameters in each layer are independent of depth. Two-layer flow field with tide and wind currents is calculated with extended ADI method, after the calculation for flow field is stable , coupled with temperature diffusion equations and thermohaline depth prediction equation, a four-day time prediction of the surface, bottom temperature and thermohaline depth of the Huanghai and the Bohai Seas. At the same time, three dimensional temperature field of sea water is predicted through vertical temperature distribution function. The result indicates that the prediction quality of the whole model and the fitting degree between the predicted result and the measured values are satisfactory.展开更多
Since 1960s, many research works on the reinforced concrete structure have been published and some concise and practical calculation methods for safety control during construction have been achieved. The reinforced co...Since 1960s, many research works on the reinforced concrete structure have been published and some concise and practical calculation methods for safety control during construction have been achieved. The reinforced concrete structure during construction is a time-dependent structure which consists of a partly completed structure and a formwork-shore system. Experience shows that the most critical condition of the time-dependent structure may happen when the formwork-shore system is partly removed or reset and accidents may occur. In the present paper, effect of ambient temperature variation between day and night is considered, new structural models for reinforced concrete frames, slab-column systems and shear wall structures are proposed, and a new software named Safety Analysis During Construction Considering Temperature(SACT) is also introduced. Compared with on-site measurements, the software SACT is validated for application on construction site.展开更多
Casting is an important rubber manufacturing process for both production and material developments. A quick and flexible way of testing the constitutive materials properties of rubber products is very important for op...Casting is an important rubber manufacturing process for both production and material developments. A quick and flexible way of testing the constitutive materials properties of rubber products is very important for optimising the processing parameters and quality control. In many cases, standard tests such as tensile or compression tests are time consuming and require a large volume of materials. This work reports some recent work in using a combined numerical and experimental approach to characterise the properties of rubber materials during a casting process. Durometer shore hardness is used to test silicone rubbers (as a model material) with different compositions on different moulding planes and the linear elastic property is estimated from the hardnesses. The predicted properties are systematically compared with the experimental tests on hard and soft silicone rubber samples with different compositions. The work shows that shore hardness can be used as an effective way to monitor the materials properties during amoulding process for process optimisation and quality control.展开更多
Copper-graphite composites were prepared by spark plasma sintering(SPS)using coppercoated graphite powder.Hydrophobic surfaces were successfully constructed by chemical etching and surface treatment.The density,metall...Copper-graphite composites were prepared by spark plasma sintering(SPS)using coppercoated graphite powder.Hydrophobic surfaces were successfully constructed by chemical etching and surface treatment.The density,metallographic structure,microstructure,Shore hardness,resistivity,water contact angle,and friction/wear properties of the composites were investigated using the Archimedes drainage method,a metallographic microscope,a scanning electron microscope,a hardness tester,a resistometer,a surface science tester,and a friction tester.The results showed that the relative density and Shore hardness of the copper-graphite composites increased slightly from 90.04%and 56 HSD to 92.66%and 59 HSD,respectively,when the sintering temperature increased from 700 to 900℃.The copper and graphite phases in the copper-graphite composites were uniformly distributed with a continuous and network-like structure at various sintering temperatures.The interface between the copper and graphite was in good condition,without any obvious cracks or voids.The optimum process for hydrophobic surface construction included etching with a 1 mol/L K_(2)Cr_(2)O_(7)-H_(2)SO_(4)solution for 1 min,and soaking in a 0.09 mol/L cetylbenzene sulfonic acid alcohol solution for 1 h.The contact angle of the copper-graphite composite reached 130°.Hydrophobic treatment was beneficial for reducing the friction coefficient(from 0.18-0.19 to 0.13-0.15)and the wear rate(from 4.1-6.2×10^(-3)to 1.1-2.1×10^(-3)mm^(3)/(N·m)),demonstrating obvious antifriction and wear-resisting properties.The resistivities of the hydrophobic-treated samples increased slightly,from(4-8)×10^(-7)Ω·m to(5-15)×10^(-7)Ω·m,meeting the resistivity requirements of copper-graphite composite pantograph sliders and current receiver sliders in actual working conditions.展开更多
The Churchill Falls Hydro Project (called the ‘Upper Churchill Development’) in Labrador [CF(L)Co], was initiated in the late 1960s. At that time, in general, not much attention was paid to the impact of such develo...The Churchill Falls Hydro Project (called the ‘Upper Churchill Development’) in Labrador [CF(L)Co], was initiated in the late 1960s. At that time, in general, not much attention was paid to the impact of such development on the flooding of vegetation, especially forest stands. Both forested and un-forested terrestrial vegetation types were flooded (244,915 ha creating some 74,075 ha of Islands) in the construction of the Main (Smallwood) Reservoir. The effect of flooding and of the constructions, both above and below the Main Reservoir major dyke system, were the subject of our investigation. This paper, the third in a series, reports on the effect of building the dykes during the early phases of construction with the descriptions of the post flooded conditions below the dykes as related to vegetation. The direct disturbances were excavations, fills, and partial and /or total removal of vegetation cover from fabrication platforms and from gravel and rock extraction sites. No new vegetation cover established in the abandoned quarries and gravel pits. However camp sites and manufacturing platforms were subsequently taken over by Alder growth. The indirect disturbances were the flooding of land areas and the de-watering of sections of the original river and lowering of the water level in some lakes. The results of flooding and the de-watering of some nearby areas are illustrated with aerial photographs and figures showing the environmental impact zones and new shore line development. The flooded trees in large and small pools of stagnant water died suddenly and remain in their original place. New vegetation cover developed on the exposed shore lines of de-watered rivers and lakes.展开更多
文摘With the commissioning of Phase$,the port of Kribi is emerging as an important maritime transport hub in Central Africa With a 715-metre quay and a draught of 16 metres,the Autonomous Port of Kribi(APK)stands as one of Africa’s most strategically significant deep-water ports.Situated on Cameroon’s Atlantic coast,it o!ers direct access to international shipping lanes and is designed to handle large-capacity vessels that many regional ports cannot accommodate.
基金Supported by Jinchang City Level Science and Technology Plan Project(No.2023RC012).
文摘The lower member of Dalazi Formation is an important oil reservoir in the Songjiang Basin.Based on the research on its field-measured geological profiles,lithological combination characteristics and grain size distribution characteristics,combined with the analysis of the spatial distribution characteristics,sedimentary structural characteristics and hydrodynamic conditions of the sediments in this member,nine sedimentary microfacies of the fan delta plain subfacies,fan delta front subfacies and littoral-shallow lacustrine subfacies have been identified.The study reveals that lower member of Dalazi Formation in the research area follows a fan delta–shallow lacustrine depositional model in the steep slope zone of a rift lake basin.The sediments primarily originate from the Pre-Mesozoic strata in the steep southeastern and eastern margins.The basin center migrated from the early Xiaoshahe area to the Yangmucun–Shenglicun area,and the sedimentary system gradually transitioned from fan delta to littoral-shallow lacustrine facies.
基金supported by the National Natural Science Foundation of China(Grant No.52001031)the National Natural Science Foundation of Hunan Province under Excellent Youth Science Fund(Grant No.2025JJ40031)supported by the U.S.National Science Foundation(Grant No.CBET-1706938)during early stages of the present study。
文摘The integration of oscillating water columns(OWCs)with piles to create a dual-function OWC-pile breakwater presents an innovative approach for harbor construction and coastline protection while enabling wave energy utilization.Local scour significantly impacts foundation safety and is crucial for structural design.This study examines wave-induced local scour at a dual-function OWC-pile breakwater through experimental methods.A high-resolution laser scanner tracked the development of 3D local scour profiles at various time intervals under regular wave conditions.The analysis focused on key parameters including scour-hole development time scale,dimensions,reflection and transmission coefficients,and energy extraction efficiency during scour evolution.The integration of OWCs substantially increased the equilibrium scour depth compared to conventional pile breakwaters,potentially affecting foundation stability.The scour profile development showed minimal impact on wave energy conversion efficiency.Wave transmission and reflection remained largely unaffected by scour holes,as verified through a semi-theoretical wave scattering model for pile breakwaters.An existing time-scale formula for predicting scour depth onset in isolated circular piles under current action demonstrated reasonable accuracy in this application.The study examines the mechanisms behind increased equilibrium scour depth due to OWCs and proposes design recommendations to mitigate scour-hole depth increases.
文摘在菲律宾薄荷岛,Panglao Shores的南棕榈度假村将艺术性、可持续性与自然景致巧妙融合,呈现一种特殊的建筑体验。由Enter Pojects Ar sia设计的这一公共空间项目,造价200万美元,不仅追求奢华,更强调生态责任、有机形态以及与海岸景观的对话。设计师的愿景是重新定义酒店建筑,使其成为周围环境的自然延展。旅程从入口开始,流畅的曲线取代了传统的直线。以藤条构筑的雕塑感门户,交织着手工艺的温暖与结构的力量,为后续空间奠定基调。
文摘There are many uncertain factors in the implementation of mining engineering. In order to guarantee the safety of mining workers' lives and property and improve the efficiency of coal mining, tunneling and supporting technology should be adopted to reduce the influence of various unfavorable factors. For example, the U-shaped steel shed support and 11805 return air lane are replaced by anchor net and cable support. The 230802 haulage lane and 230802 return air lane of Zude Coal Mine in Yunnan Dongyuan Hengding Coal Industry Co., Ltd. have changed from the original U-shaped steel shed support to the anchor net and cable support. The haulage up the hill in the second mining area of Hexing Coal Mine and the heading method of 11805 return air lane have changed from the original blasting heading to the EBZ180 heading machine heading, which not only speeds up the construction progress of the roadway but also reduces the labor intensity. Therefore, the relevant staff must combine the actual situation of the coal mining area, select the corresponding excavation and support technology, at the same time, should also strictly implement the operation procedures and safety technical measures, only in this way can the comprehensive benefit of the coal mining work be fully guaranteed.
基金supported by the National Natural Science Foundation of China (No.51379142 and No.51679163)Innovation Method Fund of China (No.2016IM030100)the Tianjin Municipal Natural Science Foundation (No.17JCYBJC22000)
文摘The wide-shallow composite bucket foundation(WSCBF) is a new type of offshore wind power foundation that can be built on land and rapidly installed offshore, there by effectively reducing the construction time and costs of offshore wind power foundation. In this study, the horizontal bearing capacity is calculated by finite element simulation and compared with test results to verify the validity of results. In this process, the vertical load and bending load are respectively calculated by the finite element simulation. Under the vertical load effect, the bucket foundation and the soil inside are regarded as a whole, and the corresponding buckling failure mode is obtained. The ultimate vertical bearing capacity is calculated using empirical and theoretical formulas; the theoretical formula is also revised by finite element results. Under bending load, the rotational center of the composite bucket foundation(in a region close to the bucket bottom) gradually moves from the left of the central axis(reverse to loading direction) to the nearby compartment boards along the loading direction. The H–M envelope line shows a linear relationship, and it is determined that the vertical and bending ultimate bearing capacities can be improved by an appropriate vertical load.
文摘Littoral-cell angioma(LCA), a primary angioma which clinically belongs to splenic hemangioma, can be mostly found in normal spleen red sinus shore cells of reticuloendothelial cell system. The cells of LCA strongly express endothelial and tissue cell associated antigens that indicate a dual differentiation characteristic; whereas only endothelial cell markers are positive in normal spleen red sinus shore cells. Diagnosis of LCA relies on histopathology. Regular follow-up is needed to monitor recurrence and metastasis.
文摘The dynamic responses of offshore fixed platforms under ice loads are analysed in this paper. The responses calculated include the displacement and the hot spot stresses on the basis of a dynamic equation of ice-induced forced vibration for offshore structures. The results obtained can be cited and used for the design and operation of offshore fixed platforms against ice loading.
文摘This study on the distribution features of petroleum hydrocarbon in water and sediment off the Fujian shore using data obtained from the baseline research on oceanic contamination in Fujian showed that: during the research period, petroleum hydrocarbon concentrations in water varied from 5.77 μg/L to 37.28 μg/L, averaged 14.48 μg/L; was lower in the wet season than in the dry season; and was highest in the Minjiang Estuary and Jiulong Estuary in both seasons. The petroleum hydrocarbon concentrations in shore sediment varied from 14.48 mg/kg to 784.36 mg/kg, averaged 133.3 mg/kg, and was closely related to sediment types (granularity).
文摘Coastal erosion phenomena in China have become increasingly evident since the end of the 1950s, and the process of coastal erosion has been speeding up simce the end of the 1970s. Almostall the coastal types, the rock coasts, the muddy coastS, the sandy coasts, the coral coasts, ets. on 32,000-km iong coastline of China are in danger of erosion, especially the beaches in open coasts and the coasts of abandoned river deltas. Although coastal erosion phenomena are extensively distributed in China, the nit6nsities of erosional processes in different regions are quite different. There are various causes of coastal erosion in China, and different factors often concurred in the coastal erosional processes. The main causes for coastal erosion are sand exploitation on shores and the decrease in river sediment discharged. Coastal erosion process has endangered the houses, roads, engineering works and tourism resources in the coastal zones.
文摘The entire Great Lakes watershed drains through Lake Ontario and flows into the St. Lawrence River near Cape Vincent, New York. The St. Lawrence River then flows northeast through Quebec and Ontario and into the largest estuary in the world, the Gulf of Saint Lawrence. The St. Lawrence River, between Ontario, Canada and New York, United States is part of the international boundary. The St. Lawrence Seaway permits ocean-going vessels to go from the Great Lakes of North America to the Atlantic Ocean. Navigation of the St. Lawrence was not possible until canals were built around the Lachine Rapids near Montreal. The canals allowed ships to by-passes the rapids and travel into Lake Ontario. In 1954, the United States agreed to joint development of the international sections of the St. Lawrence River. The St. Lawrence Seaway was opened in 1959 and permits ocean-going ships to go all the way to the southwest corner of Lake Superior near Duluth, Minnesota. During WWII, German U-boats sank several merchant marine ships and three Canadian warships in the lower St. Lawrence River, the Strait of Belle Isle, Cabot Strait and the Gulf of Saint Lawrence. The bottom of the St. Lawrence River is littered with the wreckage of these ships and other ships which were lost during storms. The International Joint Commission recommended that the Canada and United States jointly improve navigation on the St. Lawrence River from Lake Ontario to Montreal. This lead to the signing of the St. Lawrence Treaty. Steel companies supported the treaties since the new St. Lawrence Seaway could get Labrador iron ore to the United States mills in the Great Lakes region. The Seaway’s power dams generate 3.5 million kilowatts of electricity which is provided to industry and to thousands of consumers in the New York State, New England and parts of Canada. The electric power generated by the project would be shared equally. This paper highlights how the geological and landscape properties of the St. Lawrence River watershed were responsible for the successful economic development of this important and historically-rich region of North America. Planned economic and urban development of the St. Lawrence River basin by USACE was blocked by the “Save the River” campaign. Environmental challenges include disposal of treated and untreated wastewater, water pollution, and shore erosion, invasive species and flooding.
文摘In the paper, the sea is divided into two layers with density jumping, assuming that the physical parameters in each layer are independent of depth. Two-layer flow field with tide and wind currents is calculated with extended ADI method, after the calculation for flow field is stable , coupled with temperature diffusion equations and thermohaline depth prediction equation, a four-day time prediction of the surface, bottom temperature and thermohaline depth of the Huanghai and the Bohai Seas. At the same time, three dimensional temperature field of sea water is predicted through vertical temperature distribution function. The result indicates that the prediction quality of the whole model and the fitting degree between the predicted result and the measured values are satisfactory.
文摘Since 1960s, many research works on the reinforced concrete structure have been published and some concise and practical calculation methods for safety control during construction have been achieved. The reinforced concrete structure during construction is a time-dependent structure which consists of a partly completed structure and a formwork-shore system. Experience shows that the most critical condition of the time-dependent structure may happen when the formwork-shore system is partly removed or reset and accidents may occur. In the present paper, effect of ambient temperature variation between day and night is considered, new structural models for reinforced concrete frames, slab-column systems and shear wall structures are proposed, and a new software named Safety Analysis During Construction Considering Temperature(SACT) is also introduced. Compared with on-site measurements, the software SACT is validated for application on construction site.
文摘Casting is an important rubber manufacturing process for both production and material developments. A quick and flexible way of testing the constitutive materials properties of rubber products is very important for optimising the processing parameters and quality control. In many cases, standard tests such as tensile or compression tests are time consuming and require a large volume of materials. This work reports some recent work in using a combined numerical and experimental approach to characterise the properties of rubber materials during a casting process. Durometer shore hardness is used to test silicone rubbers (as a model material) with different compositions on different moulding planes and the linear elastic property is estimated from the hardnesses. The predicted properties are systematically compared with the experimental tests on hard and soft silicone rubber samples with different compositions. The work shows that shore hardness can be used as an effective way to monitor the materials properties during amoulding process for process optimisation and quality control.
基金the Open Subject of The State Key Laboratory of Heavy Duty AC Drive Electric Locomotive Systems Integration(No.172195100710)。
文摘Copper-graphite composites were prepared by spark plasma sintering(SPS)using coppercoated graphite powder.Hydrophobic surfaces were successfully constructed by chemical etching and surface treatment.The density,metallographic structure,microstructure,Shore hardness,resistivity,water contact angle,and friction/wear properties of the composites were investigated using the Archimedes drainage method,a metallographic microscope,a scanning electron microscope,a hardness tester,a resistometer,a surface science tester,and a friction tester.The results showed that the relative density and Shore hardness of the copper-graphite composites increased slightly from 90.04%and 56 HSD to 92.66%and 59 HSD,respectively,when the sintering temperature increased from 700 to 900℃.The copper and graphite phases in the copper-graphite composites were uniformly distributed with a continuous and network-like structure at various sintering temperatures.The interface between the copper and graphite was in good condition,without any obvious cracks or voids.The optimum process for hydrophobic surface construction included etching with a 1 mol/L K_(2)Cr_(2)O_(7)-H_(2)SO_(4)solution for 1 min,and soaking in a 0.09 mol/L cetylbenzene sulfonic acid alcohol solution for 1 h.The contact angle of the copper-graphite composite reached 130°.Hydrophobic treatment was beneficial for reducing the friction coefficient(from 0.18-0.19 to 0.13-0.15)and the wear rate(from 4.1-6.2×10^(-3)to 1.1-2.1×10^(-3)mm^(3)/(N·m)),demonstrating obvious antifriction and wear-resisting properties.The resistivities of the hydrophobic-treated samples increased slightly,from(4-8)×10^(-7)Ω·m to(5-15)×10^(-7)Ω·m,meeting the resistivity requirements of copper-graphite composite pantograph sliders and current receiver sliders in actual working conditions.
文摘The Churchill Falls Hydro Project (called the ‘Upper Churchill Development’) in Labrador [CF(L)Co], was initiated in the late 1960s. At that time, in general, not much attention was paid to the impact of such development on the flooding of vegetation, especially forest stands. Both forested and un-forested terrestrial vegetation types were flooded (244,915 ha creating some 74,075 ha of Islands) in the construction of the Main (Smallwood) Reservoir. The effect of flooding and of the constructions, both above and below the Main Reservoir major dyke system, were the subject of our investigation. This paper, the third in a series, reports on the effect of building the dykes during the early phases of construction with the descriptions of the post flooded conditions below the dykes as related to vegetation. The direct disturbances were excavations, fills, and partial and /or total removal of vegetation cover from fabrication platforms and from gravel and rock extraction sites. No new vegetation cover established in the abandoned quarries and gravel pits. However camp sites and manufacturing platforms were subsequently taken over by Alder growth. The indirect disturbances were the flooding of land areas and the de-watering of sections of the original river and lowering of the water level in some lakes. The results of flooding and the de-watering of some nearby areas are illustrated with aerial photographs and figures showing the environmental impact zones and new shore line development. The flooded trees in large and small pools of stagnant water died suddenly and remain in their original place. New vegetation cover developed on the exposed shore lines of de-watered rivers and lakes.
