Intermediate volatility organic compounds(IVOCs)are crucial precursors of secondary organic aerosol(SOA).In this study,gaseous IVOCs emitted from a ship main engine burning heavy fuel oil(HFO)were investigated on a te...Intermediate volatility organic compounds(IVOCs)are crucial precursors of secondary organic aerosol(SOA).In this study,gaseous IVOCs emitted from a ship main engine burning heavy fuel oil(HFO)were investigated on a test bench,which could simulate the real-world operations and emissions of ocean-going ships.The chemical compositions,emission factors(EFs)and volatility distributions of IVOC emissions were investigated.The results showed that the main engine burning HFO emitted a large amount of IVOCs,with average IVOC EFs of 20.2-201 mg/kg-fuel.The IVOCs were mainly comprised of unspeciated compounds.The chemical compositions of exhaust IVOCs were different from that of HFO fuel,especially for polycyclic aromatic compounds and alkylcyclohexanes.The volatility distributions of IVOCs were also different between HFO exhausts and HFO fuel.The distinctions in IVOC emission characteristics between HFO exhausts and HFO fuel should be considered when assessing the IVOC emission and related SOA formation potentials from ocean-going ships burning HFO,especially when using fuel-surrogate models.展开更多
Many simple nonlinear main journal bearing models have been studied theoretically, but the connection to existing engineering system has not been equally investigated. The consideration of the characteristics of engin...Many simple nonlinear main journal bearing models have been studied theoretically, but the connection to existing engineering system has not been equally investigated. The consideration of the characteristics of engine main journal bearings may provide a prediction of the bearing load and lubrication. Due to the strong non-linear features in bearing lubrication procedure, it is difficult to predict those characteristics. A non-linear dynamic model is described for analyzing the characteristics of engine main journal bearings. Components such as crankshaft, main journals and con rods are found by applying the finite element method. Non-linear spring/dampers are introduced to imitate the constraint and supporting functions provided by the main bearing and oil film. The engine gas pressure is imposed as excitation on the model via the engine piston, con rod, etc. The bearing reaction force is calculated over one engine cycle, and meanwhile, the oil film thickness and pressure distribution are obtained based on Reynolds differential equation. It can be found that the maximum bearing reaction force always occurs when the maximum cylinder pressure arises in the cylinder adjacent to that bearing. The simulated minimum oil film thickness, which is 3 μm, demonstrates the reliability of the main journal bearings. This non-linear dynamic analysis may save computing efforts of engine main bearing design and also is of good precision and close connection to actual engine main journal bearing conditions.展开更多
Only the lubrication performance at rated engine operating condition was generally analyzed in current design and research of engine connecting-rod and main bearing. However, the actual engine(especially vehicle engin...Only the lubrication performance at rated engine operating condition was generally analyzed in current design and research of engine connecting-rod and main bearing. However, the actual engine(especially vehicle engine) does not always operate in rated operating condition and its operating condition changes constantly. In this paper, a fourstroke four-cylinder engine is taken as the studying object, the load and lubrication of connecting-rod and main bearing in di erent operating conditions are analyzed. The load of connecting-rod bearing is calculated by the dynamic calculation method, the loads of all main bearings are calculated by the whole crankshaft beam-element finite element method, and the lubrication performance of connecting-rod and main bearings are analyzed by the dynamic method. The results show that there are major di erences in the changes and numerical value at corresponding moment of the loads and lubrication performance of connecting-rod and main bearings in an engine operating cycle in di erent engine operating conditions; the most unfavorable case of the lubrication performance of connectingrod and main bearings may not take place in the rated engine operating condition. There are also major di erences between the lubrication performance of connecting-rod bearing and that of main bearing and between the lubrication performances of main bearings one another. Therefore, it will not be reasonable that the lubrication performance of a certain connecting-rod bearing or main bearing is analyzed in the design of the engine bearing. It is necessary to analyze simultaneously the lubrication performances of all bearings in di erent engine operating conditions.展开更多
The effects of various split injection strategies on the opposed-piston opposed-cylinder(OPOC)diesel engine combustion and emission characteristics have been studied numerically using AVL-Fire CFD tools.The five rate-...The effects of various split injection strategies on the opposed-piston opposed-cylinder(OPOC)diesel engine combustion and emission characteristics have been studied numerically using AVL-Fire CFD tools.The five rate-shaped main injections were used in split injection strategies.The results show that ignition delay from a rectangular injection rate is the shortest.Maximum pressure of the trapezoid injection rate is the largest.And the NOx emission of the rectangular injection rate is the largest.Meanwhile,the soot emission of the trapezoid injection rate is the least among the five injection rates.展开更多
With net zero carbon emissions targets approaching over the next 20 to 30 years, the water industry must act now to develop energy efficient techniques and designs to reduce emissions and reduce the carbon footprint o...With net zero carbon emissions targets approaching over the next 20 to 30 years, the water industry must act now to develop energy efficient techniques and designs to reduce emissions and reduce the carbon footprint of water utility providers. There is also the potential for significant energy and therefore financial savings to be realised from the adoption of more energy efficient designs approaches. Water utility providers account for a significant proportion of national electricity consumption. The purpose of this research is to determine if, over the long term, opting for a larger diameter pipe at design stage can lead to significant financial and emissions savings for water utility providers when considering pumping mains. Pumping mains are widely used throughout the water and wastewater industry where a gravity solution is not possible. 72 hypothetical water main design scenarios were analysed and the long term financial and environmental impact of each hypothetical water main was assessed. It was found across all design scenarios that larger diameter water mains were capable of delivering the same rate of flow of smaller diameter pipes at a much reduced velocity and requiring reduced pumping power. It was concluded that pumped mains of larger diameters can ultimately be more energy efficient and cost effective over the long term when selected in favour of smaller diameter pumped mains in otherwise identical design scenarios.展开更多
In the process of social and economic development, with the continuous improvement of social productivity, it helps the implementation of environmental engineering construction projects and takes environmental polluti...In the process of social and economic development, with the continuous improvement of social productivity, it helps the implementation of environmental engineering construction projects and takes environmental pollution as an urgent problem to be solved at present. In the construction of environmental engineering, the contents involved are diverse. Taking sewage treatment as an example, if the treatment work in this area can be done well, the construction effect of environmental engineering can be greatly improved. In the sewage treatment stage of environmental engineering, there are various problems. In order to avoid adverse effects on the final treatment effect, it is necessary to analyze the sewage treatment process and combine the main technologies used to ensure the rationality and effectiveness of technical operation. By solving the treatment problems one by one, the effect of sewage treatment in environmental engineering can be comprehensively optimized so as to maintain a better ecological environment.展开更多
The construction project in the actual construction process, in order to comprehensively ensure the construction quality, we should strengthen the importance of the main design of the building, and through the applica...The construction project in the actual construction process, in order to comprehensively ensure the construction quality, we should strengthen the importance of the main design of the building, and through the application of standardized construction technology, reasonable control of the construction progress and quality, to ensure the smooth progress of the follow-up work. Based on this, this paper mainly around the importance of the construction of the main structure of the building to launch an analysis, elaborated the technical application countermeasures.展开更多
With the continuous development of urbanization construction, rail transit has received more and more attention. For the current subway station, the main structure of open-cut subway station plays an important role in...With the continuous development of urbanization construction, rail transit has received more and more attention. For the current subway station, the main structure of open-cut subway station plays an important role in it. Therefore, the leakage problem with high frequency should be analyzed in time and dealt with reasonably. In this paper, the construction technology of leakage treatment for the main structure of open-cut subway station is analyzed for reference.展开更多
With the rapid development of Chinese economy, Chinese construction industry has also been more significant progress and development. As one of the most commonly used building materials in engineering project construc...With the rapid development of Chinese economy, Chinese construction industry has also been more significant progress and development. As one of the most commonly used building materials in engineering project construction, the quality of cement directly determines the quality of the whole construction project and the safety of users. The construction unit shall select the appropriate test and detection method according to the actual situation and strictly control the material quality. This paper focuses on the analysis of the test and detection of cement materials and expounds the specific methods for reference.展开更多
This paper analyzes the significance of anti-seepage design and summarizes the common technology of anti-seepage design, and studies how to do a good job of anti-seepage design. Through the research, it can help the d...This paper analyzes the significance of anti-seepage design and summarizes the common technology of anti-seepage design, and studies how to do a good job of anti-seepage design. Through the research, it can help the designers to better grasp the key points of dam seepage design and prolong the service life of the dam.展开更多
The electronic information engineering industry of construction machinery industry is an important high-tech pillar industry in contemporary China. It also has important strategic significance in continuously improvin...The electronic information engineering industry of construction machinery industry is an important high-tech pillar industry in contemporary China. It also has important strategic significance in continuously improving the international technology influence level of contemporary Chinese enterprises. In order to effectively promote the further and healthy development of electronic machinery and electronic components engineering, many domestic experts and related experts have carried out more in-depth research on its application.展开更多
In recent years,China’s landscaping projects have developed vigorously,and the growth rate of urban garden green space areas has been maintained at about 5%.Overall,with the development of the national economy and th...In recent years,China’s landscaping projects have developed vigorously,and the growth rate of urban garden green space areas has been maintained at about 5%.Overall,with the development of the national economy and the support of macro policies,people’s demand for close to nature and beautify the environment is gradually increasing,which has brought new growth momentum for the development of the landscaping industry.Simultaneously,from the perspective of future economic development and urban development,the landscaping industry still has a lot of room for development.However,with the rapid development of landscape engineering,the problem of cost control of landscape engineering is becoming more prominent,the phenomenon of budget overestimation is common,and there are many factors affecting the cost of landscape engineering,which brings difficulties and challenges to the analysis of its influencing factors and cost management.How to scientifically analyze the influencing factors and control the cost has become an important link in the landscaping project.To solve the above problems,this paper takes the design stage of landscaping engineering as the background,takes the design estimate of landscaping engineering as the research object,through literature research and data collection,fully excavates the main influencing factors of the design estimate stage of landscaping engineering,analyzes the key points of cost control,and provides reference ideas and directions for the later cost management and control.展开更多
For construction engineering, large-capacity concrete is often used in large construction projects different from conventional concrete construction, large-capacity concrete has specific requirements for the construct...For construction engineering, large-capacity concrete is often used in large construction projects different from conventional concrete construction, large-capacity concrete has specific requirements for the construction process. Concrete is an important part of construction engineering, and its role in construction engineering is clear. Based on this, construction departments need to make clear the key points of volume concrete construction technology to improve the quality of construction engineering. This paper analyzes the key points of construction technology of mass concrete and clarifies the details of technology application in order to promote the improvement of construction quality.展开更多
This paper focuses on the research of the main transformer selection and layout scheme for new energy step-up substations.From the perspective of engineering design,it analyzes the principles of main transformer selec...This paper focuses on the research of the main transformer selection and layout scheme for new energy step-up substations.From the perspective of engineering design,it analyzes the principles of main transformer selection,key parameters,and their matching with the characteristics of new energy.It also explores the layout methods and optimization strategies.Combined with typical case studies,optimization suggestions are proposed for the design of main transformers in new energy step-up substations.The research shows that rational main transformer selection and scientific layout schemes can better adapt to the characteristics of new energy projects while effectively improving land use efficiency and economic viability.This study can provide technical experience support for the design of new energy projects.展开更多
Determining the main controlling factors of earthquake-triggered geohazards is a prerequisite for studying earthquake geohazards and post-disaster emergency response.By studying these factors,the geomorphic and geolog...Determining the main controlling factors of earthquake-triggered geohazards is a prerequisite for studying earthquake geohazards and post-disaster emergency response.By studying these factors,the geomorphic and geological factors controlling the nature,condition,and distribution of earthquake-induced geohazards can be analyzed.Such insights facilitate earthquake disaster prediction and emergency response planning.The authors combined field investigations and spatial data analysis to examine geohazards induced by seismic events,examining ten earthquakes including the Wenchuan,Yushu,Lushan events,to elucidate the main control factors of seismic geohazard.The authors observed that seismic geohazard occurrence is usually affected by many factors,among which active nature of the seismogenic fault,seismic peak ground acceleration(PGA),topographic slope and geomorphic height differences,and distance from the fault zone and river system are the most important.Compared with strike-slip earthquakes,thrust earthquakes induce more high-altitude and high-speed remote landslides,which can cause great harm.Slopes of 0°–40°are prone to secondary seismic geohazards,which are mainly concentrated 0–6 km from the river system.Secondary geohazards are not only related to seismogenic fault but also influenced by the associated faults in the earthquake area.The maximum seismic PGA and secondary seismic geohazard number are positively correlated,and the horizontal and vertical ground motions play leading and promoting roles in secondary geohazard formation,respectively.Through the research,the spatial distribution of seismic geohazards is predicted,providing a basis for the formulation of emergency response plans following disasters.展开更多
To study the additional aerodynamic effect on a bridge girder under the action of wind-driven rain, the rainfall similarity considering raindrop impact and surface water is first given. Then, the dynamic characteristi...To study the additional aerodynamic effect on a bridge girder under the action of wind-driven rain, the rainfall similarity considering raindrop impact and surface water is first given. Then, the dynamic characteristics and the process of vortex and flutter generation of the segment models under different rain intensities and angles of attack are tested by considering several typical main girder sections as examples. The test results indicate that the start and end wind speeds,interval length and number of vortex vibrations remain unchanged when it is raining, rainfall will reduce the windinduced vortex response. When test rain intensity is large, the decrease of amplitude is obvious. However, after considering the rain intensity similarity in this study, all of actual maximum rain intensities after conversion approach the domestic extreme rain intensity of approximately 709 mm/h. It can be observed that rainfall has a limited influence on the dynamic characteristics of the structure and vortex vibration response. When the test rain intensity is 120 mm/h, the critical wind speed of the model flutter increases by 20%-30%. However, after considering the rain intensity similarity ratio, the influence of rainfall on the wind-induced flutter instability of the bridge girder may be ignored.展开更多
Power generation is one of the most essential functions of any plant for continuous functioning without any interruption. A marine power plant （MPP） is the same section. In the present paper, the authors have tried ...Power generation is one of the most essential functions of any plant for continuous functioning without any interruption. A marine power plant （MPP） is the same section. In the present paper, the authors have tried to find the various reliability characteristics of an MPR A marine power plant which is a composition of two generators and in which one of them is located at the stern and another at the bow, both associated to the main switchboard （MSB）. The distribution switchboards （DSB） receive power from the MSB through cables and their respective junctions. Given that arrangement, a working based transition state diagram has been generated. With the help of the Markov process, a number of intro-differential equations are formed and solved by Laplace transform. Various reliability characteristics are calculated and discussed with the help of graphs.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 41403084 and 4171101108)the Project from Shanghai Committee of Science and Technology (No. 16ZR1414800
文摘Intermediate volatility organic compounds(IVOCs)are crucial precursors of secondary organic aerosol(SOA).In this study,gaseous IVOCs emitted from a ship main engine burning heavy fuel oil(HFO)were investigated on a test bench,which could simulate the real-world operations and emissions of ocean-going ships.The chemical compositions,emission factors(EFs)and volatility distributions of IVOC emissions were investigated.The results showed that the main engine burning HFO emitted a large amount of IVOCs,with average IVOC EFs of 20.2-201 mg/kg-fuel.The IVOCs were mainly comprised of unspeciated compounds.The chemical compositions of exhaust IVOCs were different from that of HFO fuel,especially for polycyclic aromatic compounds and alkylcyclohexanes.The volatility distributions of IVOCs were also different between HFO exhausts and HFO fuel.The distinctions in IVOC emission characteristics between HFO exhausts and HFO fuel should be considered when assessing the IVOC emission and related SOA formation potentials from ocean-going ships burning HFO,especially when using fuel-surrogate models.
基金supported by National Natural Science Foundation of China (Grant No. 60879002)National Hi-tech Research and Development Program of China (863 Program, Grant No. 2006AA110112)
文摘Many simple nonlinear main journal bearing models have been studied theoretically, but the connection to existing engineering system has not been equally investigated. The consideration of the characteristics of engine main journal bearings may provide a prediction of the bearing load and lubrication. Due to the strong non-linear features in bearing lubrication procedure, it is difficult to predict those characteristics. A non-linear dynamic model is described for analyzing the characteristics of engine main journal bearings. Components such as crankshaft, main journals and con rods are found by applying the finite element method. Non-linear spring/dampers are introduced to imitate the constraint and supporting functions provided by the main bearing and oil film. The engine gas pressure is imposed as excitation on the model via the engine piston, con rod, etc. The bearing reaction force is calculated over one engine cycle, and meanwhile, the oil film thickness and pressure distribution are obtained based on Reynolds differential equation. It can be found that the maximum bearing reaction force always occurs when the maximum cylinder pressure arises in the cylinder adjacent to that bearing. The simulated minimum oil film thickness, which is 3 μm, demonstrates the reliability of the main journal bearings. This non-linear dynamic analysis may save computing efforts of engine main bearing design and also is of good precision and close connection to actual engine main journal bearing conditions.
基金Supported by Science Fund of State Key Laboratory of Engine Reliability of China(Grant No.skler-201708)National Natural Science Foundation of China(Grant No.51490660/51490661)
文摘Only the lubrication performance at rated engine operating condition was generally analyzed in current design and research of engine connecting-rod and main bearing. However, the actual engine(especially vehicle engine) does not always operate in rated operating condition and its operating condition changes constantly. In this paper, a fourstroke four-cylinder engine is taken as the studying object, the load and lubrication of connecting-rod and main bearing in di erent operating conditions are analyzed. The load of connecting-rod bearing is calculated by the dynamic calculation method, the loads of all main bearings are calculated by the whole crankshaft beam-element finite element method, and the lubrication performance of connecting-rod and main bearings are analyzed by the dynamic method. The results show that there are major di erences in the changes and numerical value at corresponding moment of the loads and lubrication performance of connecting-rod and main bearings in an engine operating cycle in di erent engine operating conditions; the most unfavorable case of the lubrication performance of connectingrod and main bearings may not take place in the rated engine operating condition. There are also major di erences between the lubrication performance of connecting-rod bearing and that of main bearing and between the lubrication performances of main bearings one another. Therefore, it will not be reasonable that the lubrication performance of a certain connecting-rod bearing or main bearing is analyzed in the design of the engine bearing. It is necessary to analyze simultaneously the lubrication performances of all bearings in di erent engine operating conditions.
基金Supported by the National Natural Science Foundation of China(51605447)
文摘The effects of various split injection strategies on the opposed-piston opposed-cylinder(OPOC)diesel engine combustion and emission characteristics have been studied numerically using AVL-Fire CFD tools.The five rate-shaped main injections were used in split injection strategies.The results show that ignition delay from a rectangular injection rate is the shortest.Maximum pressure of the trapezoid injection rate is the largest.And the NOx emission of the rectangular injection rate is the largest.Meanwhile,the soot emission of the trapezoid injection rate is the least among the five injection rates.
文摘With net zero carbon emissions targets approaching over the next 20 to 30 years, the water industry must act now to develop energy efficient techniques and designs to reduce emissions and reduce the carbon footprint of water utility providers. There is also the potential for significant energy and therefore financial savings to be realised from the adoption of more energy efficient designs approaches. Water utility providers account for a significant proportion of national electricity consumption. The purpose of this research is to determine if, over the long term, opting for a larger diameter pipe at design stage can lead to significant financial and emissions savings for water utility providers when considering pumping mains. Pumping mains are widely used throughout the water and wastewater industry where a gravity solution is not possible. 72 hypothetical water main design scenarios were analysed and the long term financial and environmental impact of each hypothetical water main was assessed. It was found across all design scenarios that larger diameter water mains were capable of delivering the same rate of flow of smaller diameter pipes at a much reduced velocity and requiring reduced pumping power. It was concluded that pumped mains of larger diameters can ultimately be more energy efficient and cost effective over the long term when selected in favour of smaller diameter pumped mains in otherwise identical design scenarios.
文摘In the process of social and economic development, with the continuous improvement of social productivity, it helps the implementation of environmental engineering construction projects and takes environmental pollution as an urgent problem to be solved at present. In the construction of environmental engineering, the contents involved are diverse. Taking sewage treatment as an example, if the treatment work in this area can be done well, the construction effect of environmental engineering can be greatly improved. In the sewage treatment stage of environmental engineering, there are various problems. In order to avoid adverse effects on the final treatment effect, it is necessary to analyze the sewage treatment process and combine the main technologies used to ensure the rationality and effectiveness of technical operation. By solving the treatment problems one by one, the effect of sewage treatment in environmental engineering can be comprehensively optimized so as to maintain a better ecological environment.
文摘The construction project in the actual construction process, in order to comprehensively ensure the construction quality, we should strengthen the importance of the main design of the building, and through the application of standardized construction technology, reasonable control of the construction progress and quality, to ensure the smooth progress of the follow-up work. Based on this, this paper mainly around the importance of the construction of the main structure of the building to launch an analysis, elaborated the technical application countermeasures.
文摘With the continuous development of urbanization construction, rail transit has received more and more attention. For the current subway station, the main structure of open-cut subway station plays an important role in it. Therefore, the leakage problem with high frequency should be analyzed in time and dealt with reasonably. In this paper, the construction technology of leakage treatment for the main structure of open-cut subway station is analyzed for reference.
文摘With the rapid development of Chinese economy, Chinese construction industry has also been more significant progress and development. As one of the most commonly used building materials in engineering project construction, the quality of cement directly determines the quality of the whole construction project and the safety of users. The construction unit shall select the appropriate test and detection method according to the actual situation and strictly control the material quality. This paper focuses on the analysis of the test and detection of cement materials and expounds the specific methods for reference.
文摘This paper analyzes the significance of anti-seepage design and summarizes the common technology of anti-seepage design, and studies how to do a good job of anti-seepage design. Through the research, it can help the designers to better grasp the key points of dam seepage design and prolong the service life of the dam.
文摘The electronic information engineering industry of construction machinery industry is an important high-tech pillar industry in contemporary China. It also has important strategic significance in continuously improving the international technology influence level of contemporary Chinese enterprises. In order to effectively promote the further and healthy development of electronic machinery and electronic components engineering, many domestic experts and related experts have carried out more in-depth research on its application.
文摘In recent years,China’s landscaping projects have developed vigorously,and the growth rate of urban garden green space areas has been maintained at about 5%.Overall,with the development of the national economy and the support of macro policies,people’s demand for close to nature and beautify the environment is gradually increasing,which has brought new growth momentum for the development of the landscaping industry.Simultaneously,from the perspective of future economic development and urban development,the landscaping industry still has a lot of room for development.However,with the rapid development of landscape engineering,the problem of cost control of landscape engineering is becoming more prominent,the phenomenon of budget overestimation is common,and there are many factors affecting the cost of landscape engineering,which brings difficulties and challenges to the analysis of its influencing factors and cost management.How to scientifically analyze the influencing factors and control the cost has become an important link in the landscaping project.To solve the above problems,this paper takes the design stage of landscaping engineering as the background,takes the design estimate of landscaping engineering as the research object,through literature research and data collection,fully excavates the main influencing factors of the design estimate stage of landscaping engineering,analyzes the key points of cost control,and provides reference ideas and directions for the later cost management and control.
文摘For construction engineering, large-capacity concrete is often used in large construction projects different from conventional concrete construction, large-capacity concrete has specific requirements for the construction process. Concrete is an important part of construction engineering, and its role in construction engineering is clear. Based on this, construction departments need to make clear the key points of volume concrete construction technology to improve the quality of construction engineering. This paper analyzes the key points of construction technology of mass concrete and clarifies the details of technology application in order to promote the improvement of construction quality.
文摘This paper focuses on the research of the main transformer selection and layout scheme for new energy step-up substations.From the perspective of engineering design,it analyzes the principles of main transformer selection,key parameters,and their matching with the characteristics of new energy.It also explores the layout methods and optimization strategies.Combined with typical case studies,optimization suggestions are proposed for the design of main transformers in new energy step-up substations.The research shows that rational main transformer selection and scientific layout schemes can better adapt to the characteristics of new energy projects while effectively improving land use efficiency and economic viability.This study can provide technical experience support for the design of new energy projects.
基金supported by the National Natural Science Foundation of China(41977258)the National Key Research and Development Program of China(2017YFC1501005 and 2018YFC1504704)。
文摘Determining the main controlling factors of earthquake-triggered geohazards is a prerequisite for studying earthquake geohazards and post-disaster emergency response.By studying these factors,the geomorphic and geological factors controlling the nature,condition,and distribution of earthquake-induced geohazards can be analyzed.Such insights facilitate earthquake disaster prediction and emergency response planning.The authors combined field investigations and spatial data analysis to examine geohazards induced by seismic events,examining ten earthquakes including the Wenchuan,Yushu,Lushan events,to elucidate the main control factors of seismic geohazard.The authors observed that seismic geohazard occurrence is usually affected by many factors,among which active nature of the seismogenic fault,seismic peak ground acceleration(PGA),topographic slope and geomorphic height differences,and distance from the fault zone and river system are the most important.Compared with strike-slip earthquakes,thrust earthquakes induce more high-altitude and high-speed remote landslides,which can cause great harm.Slopes of 0°–40°are prone to secondary seismic geohazards,which are mainly concentrated 0–6 km from the river system.Secondary geohazards are not only related to seismogenic fault but also influenced by the associated faults in the earthquake area.The maximum seismic PGA and secondary seismic geohazard number are positively correlated,and the horizontal and vertical ground motions play leading and promoting roles in secondary geohazard formation,respectively.Through the research,the spatial distribution of seismic geohazards is predicted,providing a basis for the formulation of emergency response plans following disasters.
基金Projects(20B062,19B054)supported by Excellent Youth Program of Hunan Education Department,ChinaProject(2019JJ50688)supported by Hunan Provincial Natural Science Foundation of ChinaProject(kq195004)supported by Changsha Science and Technology Bureau Project,China。
文摘To study the additional aerodynamic effect on a bridge girder under the action of wind-driven rain, the rainfall similarity considering raindrop impact and surface water is first given. Then, the dynamic characteristics and the process of vortex and flutter generation of the segment models under different rain intensities and angles of attack are tested by considering several typical main girder sections as examples. The test results indicate that the start and end wind speeds,interval length and number of vortex vibrations remain unchanged when it is raining, rainfall will reduce the windinduced vortex response. When test rain intensity is large, the decrease of amplitude is obvious. However, after considering the rain intensity similarity in this study, all of actual maximum rain intensities after conversion approach the domestic extreme rain intensity of approximately 709 mm/h. It can be observed that rainfall has a limited influence on the dynamic characteristics of the structure and vortex vibration response. When the test rain intensity is 120 mm/h, the critical wind speed of the model flutter increases by 20%-30%. However, after considering the rain intensity similarity ratio, the influence of rainfall on the wind-induced flutter instability of the bridge girder may be ignored.
文摘Power generation is one of the most essential functions of any plant for continuous functioning without any interruption. A marine power plant （MPP） is the same section. In the present paper, the authors have tried to find the various reliability characteristics of an MPR A marine power plant which is a composition of two generators and in which one of them is located at the stern and another at the bow, both associated to the main switchboard （MSB）. The distribution switchboards （DSB） receive power from the MSB through cables and their respective junctions. Given that arrangement, a working based transition state diagram has been generated. With the help of the Markov process, a number of intro-differential equations are formed and solved by Laplace transform. Various reliability characteristics are calculated and discussed with the help of graphs.
