Considering arch rib, lateral brace, suspender, girder, pier and track position, the model for the interaction between long-span tied arch continuous bridge and multiple tracks was established by using steel-concrete ...Considering arch rib, lateral brace, suspender, girder, pier and track position, the model for the interaction between long-span tied arch continuous bridge and multiple tracks was established by using steel-concrete composite section beam element to simulate concrete-filled steel tube(CFST) arch rib, using the beam element with rigid arm to simulate the prestressed concrete girder and using nonlinear bar element to simulate longitudinal constraint between track and bridge. Taking a(77+3×156.8+77) m tied arch continuous bridge with four tracks on the Harbin-Qiqihar Passenger Dedicated Line as an example, the arrangement of continuously welded rail(CWR) was explored. The longitudinal force in CWR on the tied arch continuous bridge, the pier top horizontal force and torque due to the unbalance load case, were analyzed under the action of temperature, vertical live load, train braking and wind load.Studies show that, it can significantly reduce track displacement to set the track expansion devices at main span arch springing on both sides; the track stress due to arch temperature variation can reach 40.8 MPa; the track stress, pier top horizontal force and torque are related to the number of loaded tracks and train running direction, and the bending force applied to unloaded track is close to the loaded track, while the braking force applied to unloaded track is 1/4 to 1/2 of the loaded track; the longitudinal force of track due to the wind load is up to 12.4 MPa, which should be considered.展开更多
This paper presents an optimization algorithm for the design of tied back retaining wall which is comprised of the same three basic elements: stem, toe and heel, where the stem is hinged to the base and tied to the he...This paper presents an optimization algorithm for the design of tied back retaining wall which is comprised of the same three basic elements: stem, toe and heel, where the stem is hinged to the base and tied to the heel by multiple tie rods at intervals along the wall. The aim of this study is to find the values of design variables for this suggested type of tied back retaining walls which minimize the cost function subjected to constraints of the problem. The optimum design of such structure is conducted by using one of the nontraditional optimization methods, genetic algorithm (GA). The formulation of the problem is based on the elastic analysis and the ultimate strength method of design as per ACI-318-2011 code. The built-in genetic algorithm optimtool of Matlab program is utilized to optimize the cost function of the wall. The cost of concrete, reinforcing steel, tie steel, formwork, excavation, and backfilling works are included. The considered design variables are the geometric dimensions and the amounts of reinforcement for the base slab and stem slab, as well as the amount of tie steel. The developed program is utilized to perform an extensive parametric study regarding the height of wall, backfill soil properties, and materials properties including concrete, reinforcing steel, and tie steel. The backfill properties are represented by a pressure coefficient, which is a function of the unit weight and the angle of internal friction. Average expressions are calculated for the total cost and optimum dimensions as ratios of the wall height H2 which may be useful for the practical design of walls.展开更多
The success of new scientific areas can be assessed by their potential for contributing to new theoretical approaches aligned with real-world applications.The Euclidean distance transform(EDT)has fared well in both ca...The success of new scientific areas can be assessed by their potential for contributing to new theoretical approaches aligned with real-world applications.The Euclidean distance transform(EDT)has fared well in both cases,providing a sound theoretical basis for a number of applications,such as median axis transform,fractal analysis,skeletonization,and Voronoi diagrams.Despite its wide applicability,the discrete form of the EDT includes interesting properties that have not yet been fully exploited in the literature.In this paper,we are particularly interested in the properties of 1)working with multiple objects/labels;and 2)identifying and counting equidistant pixels/voxels from certain points of interest.In some domains(such as dataset classification,texture,and complexity analysis),the result of applying the EDT transform with different objects,and their respective tied distances,may compromise the performance.In this sense,we propose an efficient modification in the method presented in[1],which leads to a novel approach for computing the distance transform in a space with multiple objects,and for counting equidistant pixels/voxels.展开更多
Mono cropping is the dominant factor influencing plant nutrient uptake and loss of soil quality in Ethiopia whereas intercropping of cereal/legume has positive environmental qualities. Likewise drought and moisture st...Mono cropping is the dominant factor influencing plant nutrient uptake and loss of soil quality in Ethiopia whereas intercropping of cereal/legume has positive environmental qualities. Likewise drought and moisture stress condition is widely expanding from all direction to the center of the country. Therefore, the objective of this research was to evaluate influence of planting methods, tied ridge and cropping system on different soil chemical properties in case of Madda Walabu district, Southeast Ethiopia. It was undertaken at Bidire from March 2016 to January, 2017. In this experiment, one maize variety (Melkassa 2) and one haricot bean variety (Nasir) were used. Treatments include open end and closed end tied ridge;sole cropping and intercropping;and in furrow, on ridge and flat bed planting. Each treatment has been triplicate and the experiment plots were laid out in randomized complete block design. Intercropping of maize-haricot bean with tied ridge and planting methods were highly influenced soil pH, exchangeable potassium, available phosphorous, soil organic matter and total soil nitrogen. Generally, the use of intercropping and closed end tied ridge in combination with in furrow planting significantly increased (p0.05) soil fertility in the system, which could be promising for sustainable improvement of crop production and productivity for semi arid areas of Bale zone.展开更多
Major problem with grid tied micro wind turbine is synchronization and wind variability. Due to this problem the stability of available grid gets reduced. The stability can be achieved by output power control of the t...Major problem with grid tied micro wind turbine is synchronization and wind variability. Due to this problem the stability of available grid gets reduced. The stability can be achieved by output power control of the turbine. Major part of many countries like India, the annual mean wind speed is not high. The rated wind speed of turbine remain around 11 m/s and cut in is around 3.5 m/s. Due to this problem we aimed to develop a sustainable wind energy system that can provide stable power supply even at the locations of low wind speed of 2 - 4 m/s. To address this issue, a momentary impulse or external torque to the rotor by external motor is one of the good options to maintain the momentum of blades and thus provide stability for sufficient time. Various theoretical calculations and experiments are conducted on the above method. This would increase the output power and also the efficiency of wind turbine. We show that Return-On-Investment will be high as compared with other grid connected turbines. Our proposed concept in the present study, if implemented properly, can help the installation of number of wind turbines even at domestic level. It also makes the consumers energy independent and promotes the use of wind as a source of energy and may enter as a rooftop energy supply system similar to solar.展开更多
Simply-supported tied arch is a zero-thrust arch bridge with clear structural force,large stiffness,low height,beautiful appearance and economic efficiency.In Xuzhou-Shanghai section of Beijing-Shanghai HSR,the simply...Simply-supported tied arch is a zero-thrust arch bridge with clear structural force,large stiffness,low height,beautiful appearance and economic efficiency.In Xuzhou-Shanghai section of Beijing-Shanghai HSR,the simply-supported tied arch is systematically studied and widely applied for the first time.A total of 21 simplysupported tied arch bridges with the spans of 96 m,112 m and 128 m respectively are constructed for the route.The simply-supported tied arch is an external static and internal super-static parallel arch or basket arch of Nielsen system in structure;single-box,threechamber and equal-height prestressed concrete box girder is adopted for the tie beam;dumbbell steel pipe concrete section is adopted for the arch rib;PES(FD)low-stress anticorrosion cable body is adopted for the suspender.The rational structural form is determined by comparative study on the key technical parameters such as the layout form of suspender,rise-span ratio and arch axis alignment.This paper summarizes the optimization of simplysupported tied arch structure and looks forward to the development of bridge structure.展开更多
“The holidays are over,”Mother smiled.“New classesstart tomorrow,so get to bed early.From now on your studiesare going to tie you down.”Penelope groaned.“Gee,we’re
Bridge construction has received a lot of attention as transportation continues to improve.Reinforced concrete linked arch bridges are a common bridge style in today’s bridge construction.This type of bridge not only...Bridge construction has received a lot of attention as transportation continues to improve.Reinforced concrete linked arch bridges are a common bridge style in today’s bridge construction.This type of bridge not only has a basic and generous shape,but it is also incredibly easy to construct,resulting in significant material and construction cost savings.This article analyzes the construction technology of a reinforced concrete linked arch bridge in order to achieve good construction and application.It is hoped that this analysis can provide a scientific reference for the guarantee of the construction quality and subsequent application effect of this kind of bridge.展开更多
In order to ensure the construction quality and safety of small and medium span basket type steel box tied arch bridge,this paper takes a practical project as an example to analyze the key technologies in its design p...In order to ensure the construction quality and safety of small and medium span basket type steel box tied arch bridge,this paper takes a practical project as an example to analyze the key technologies in its design process.It is hoped that this analysis can provide corresponding reference for the design and construction of this kind of arch bridge.展开更多
Tracking the maximum power point is a critical issue with solar systems.The power output of the solar panel varies due to variations in irradiance and temperature.Nonuniform irradiation due to partial shading conditio...Tracking the maximum power point is a critical issue with solar systems.The power output of the solar panel varies due to variations in irradiance and temperature.Nonuniform irradiation due to partial shading conditions has a direct impact on the characteristics of photovoltaic(PV)systems.To build a diversity of maximum power point tracking algorithms in solar PV systems,this work focuses on perturb and observe,incremental conductance,and fuzzy logic control methodologies.The suggested fuzzy logic control method outperformed the conventional incremental conductance and perturb and observe algorithms with a collection of 49 rules.This paper presents a novel series-parallel-cross-tied PV array configuration with a developed fuzzy methodology.To comment on the performance of a proposed system under various partial shading conditions,a series-parallel PV array configuration has been considered.The simulation result demonstrates that the fuzzy method has a percentage improvement in the global maximum power point tracking efficiency of 24.85%when compared to the perturb and observe method and a 65.5%improvement when compared to the incremental conductance method under long wide partial shading conditions.In the case of the middle partial shading condition,the fuzzy method has a percentage improvement in the global maximum power point tracking efficiency of 12.4%compared to the perturb and observe method and a 60.7%improvement compared to the incremental conductance method.展开更多
选注者言:5月24日世界卫生组织解除了香港和广州的旅游警告,同一天,香港和深圳的科学家联合声明在野生动物masked palm civets(果子狸)身上发现了与人类SARS病毒一致的病原体,人类对SARS的战斗胜利越来越近!想起5月的《科技英语学习》...选注者言:5月24日世界卫生组织解除了香港和广州的旅游警告,同一天,香港和深圳的科学家联合声明在野生动物masked palm civets(果子狸)身上发现了与人类SARS病毒一致的病原体,人类对SARS的战斗胜利越来越近!想起5月的《科技英语学习》上第一篇文章中的一句话…the Canadian are telling them(Chinese in China Town),you dirty Chinese,you eat everything,that’S why展开更多
British Prime Minister Keir Starmer’s visit to China underscores economic cooperation and strategic stability amid global uncertainties.U.K.Prime Minister Keir Starmer’s visit to China in January marks a significant...British Prime Minister Keir Starmer’s visit to China underscores economic cooperation and strategic stability amid global uncertainties.U.K.Prime Minister Keir Starmer’s visit to China in January marks a significant shift of Britain toward a more pragmatic and stability-oriented approach in Sino-British relations.After years of political tensions and limited high-level engagement,this trip underscores London’s intent to rebuild ties based on mutual economic and strategic interests.展开更多
British Prime Minister Keir Starmer’s China visit has yielded a new commitment to a long-term stable comprehensive strategic partnership,with significant breakthroughs in financial cooperation including a newly estab...British Prime Minister Keir Starmer’s China visit has yielded a new commitment to a long-term stable comprehensive strategic partnership,with significant breakthroughs in financial cooperation including a newly established financial working group.THE four-day visit of British Prime Minister Keir Starmer to China-the first by a U.K.Prime Minister in eight years-has marked a significant step toward stabilizing and deepening bilateral relations.展开更多
基金Project(51378503)supported by the National Natural Science Foundation of ChinaProject(2014M552158)supported by China Postdoctoral Science Foundation
文摘Considering arch rib, lateral brace, suspender, girder, pier and track position, the model for the interaction between long-span tied arch continuous bridge and multiple tracks was established by using steel-concrete composite section beam element to simulate concrete-filled steel tube(CFST) arch rib, using the beam element with rigid arm to simulate the prestressed concrete girder and using nonlinear bar element to simulate longitudinal constraint between track and bridge. Taking a(77+3×156.8+77) m tied arch continuous bridge with four tracks on the Harbin-Qiqihar Passenger Dedicated Line as an example, the arrangement of continuously welded rail(CWR) was explored. The longitudinal force in CWR on the tied arch continuous bridge, the pier top horizontal force and torque due to the unbalance load case, were analyzed under the action of temperature, vertical live load, train braking and wind load.Studies show that, it can significantly reduce track displacement to set the track expansion devices at main span arch springing on both sides; the track stress due to arch temperature variation can reach 40.8 MPa; the track stress, pier top horizontal force and torque are related to the number of loaded tracks and train running direction, and the bending force applied to unloaded track is close to the loaded track, while the braking force applied to unloaded track is 1/4 to 1/2 of the loaded track; the longitudinal force of track due to the wind load is up to 12.4 MPa, which should be considered.
文摘This paper presents an optimization algorithm for the design of tied back retaining wall which is comprised of the same three basic elements: stem, toe and heel, where the stem is hinged to the base and tied to the heel by multiple tie rods at intervals along the wall. The aim of this study is to find the values of design variables for this suggested type of tied back retaining walls which minimize the cost function subjected to constraints of the problem. The optimum design of such structure is conducted by using one of the nontraditional optimization methods, genetic algorithm (GA). The formulation of the problem is based on the elastic analysis and the ultimate strength method of design as per ACI-318-2011 code. The built-in genetic algorithm optimtool of Matlab program is utilized to optimize the cost function of the wall. The cost of concrete, reinforcing steel, tie steel, formwork, excavation, and backfilling works are included. The considered design variables are the geometric dimensions and the amounts of reinforcement for the base slab and stem slab, as well as the amount of tie steel. The developed program is utilized to perform an extensive parametric study regarding the height of wall, backfill soil properties, and materials properties including concrete, reinforcing steel, and tie steel. The backfill properties are represented by a pressure coefficient, which is a function of the unit weight and the angle of internal friction. Average expressions are calculated for the total cost and optimum dimensions as ratios of the wall height H2 which may be useful for the practical design of walls.
基金supported by the Brazilian National Council for Scientific and Technological Development(CNPq)Araucaria Foundation+1 种基金Coordination for the Improvement of Higher Education Personnel(CAPES)Funding Authority for Studies and Projects(FINEP)。
文摘The success of new scientific areas can be assessed by their potential for contributing to new theoretical approaches aligned with real-world applications.The Euclidean distance transform(EDT)has fared well in both cases,providing a sound theoretical basis for a number of applications,such as median axis transform,fractal analysis,skeletonization,and Voronoi diagrams.Despite its wide applicability,the discrete form of the EDT includes interesting properties that have not yet been fully exploited in the literature.In this paper,we are particularly interested in the properties of 1)working with multiple objects/labels;and 2)identifying and counting equidistant pixels/voxels from certain points of interest.In some domains(such as dataset classification,texture,and complexity analysis),the result of applying the EDT transform with different objects,and their respective tied distances,may compromise the performance.In this sense,we propose an efficient modification in the method presented in[1],which leads to a novel approach for computing the distance transform in a space with multiple objects,and for counting equidistant pixels/voxels.
文摘Mono cropping is the dominant factor influencing plant nutrient uptake and loss of soil quality in Ethiopia whereas intercropping of cereal/legume has positive environmental qualities. Likewise drought and moisture stress condition is widely expanding from all direction to the center of the country. Therefore, the objective of this research was to evaluate influence of planting methods, tied ridge and cropping system on different soil chemical properties in case of Madda Walabu district, Southeast Ethiopia. It was undertaken at Bidire from March 2016 to January, 2017. In this experiment, one maize variety (Melkassa 2) and one haricot bean variety (Nasir) were used. Treatments include open end and closed end tied ridge;sole cropping and intercropping;and in furrow, on ridge and flat bed planting. Each treatment has been triplicate and the experiment plots were laid out in randomized complete block design. Intercropping of maize-haricot bean with tied ridge and planting methods were highly influenced soil pH, exchangeable potassium, available phosphorous, soil organic matter and total soil nitrogen. Generally, the use of intercropping and closed end tied ridge in combination with in furrow planting significantly increased (p0.05) soil fertility in the system, which could be promising for sustainable improvement of crop production and productivity for semi arid areas of Bale zone.
文摘Major problem with grid tied micro wind turbine is synchronization and wind variability. Due to this problem the stability of available grid gets reduced. The stability can be achieved by output power control of the turbine. Major part of many countries like India, the annual mean wind speed is not high. The rated wind speed of turbine remain around 11 m/s and cut in is around 3.5 m/s. Due to this problem we aimed to develop a sustainable wind energy system that can provide stable power supply even at the locations of low wind speed of 2 - 4 m/s. To address this issue, a momentary impulse or external torque to the rotor by external motor is one of the good options to maintain the momentum of blades and thus provide stability for sufficient time. Various theoretical calculations and experiments are conducted on the above method. This would increase the output power and also the efficiency of wind turbine. We show that Return-On-Investment will be high as compared with other grid connected turbines. Our proposed concept in the present study, if implemented properly, can help the installation of number of wind turbines even at domestic level. It also makes the consumers energy independent and promotes the use of wind as a source of energy and may enter as a rooftop energy supply system similar to solar.
文摘Simply-supported tied arch is a zero-thrust arch bridge with clear structural force,large stiffness,low height,beautiful appearance and economic efficiency.In Xuzhou-Shanghai section of Beijing-Shanghai HSR,the simply-supported tied arch is systematically studied and widely applied for the first time.A total of 21 simplysupported tied arch bridges with the spans of 96 m,112 m and 128 m respectively are constructed for the route.The simply-supported tied arch is an external static and internal super-static parallel arch or basket arch of Nielsen system in structure;single-box,threechamber and equal-height prestressed concrete box girder is adopted for the tie beam;dumbbell steel pipe concrete section is adopted for the arch rib;PES(FD)low-stress anticorrosion cable body is adopted for the suspender.The rational structural form is determined by comparative study on the key technical parameters such as the layout form of suspender,rise-span ratio and arch axis alignment.This paper summarizes the optimization of simplysupported tied arch structure and looks forward to the development of bridge structure.
文摘“The holidays are over,”Mother smiled.“New classesstart tomorrow,so get to bed early.From now on your studiesare going to tie you down.”Penelope groaned.“Gee,we’re
文摘Bridge construction has received a lot of attention as transportation continues to improve.Reinforced concrete linked arch bridges are a common bridge style in today’s bridge construction.This type of bridge not only has a basic and generous shape,but it is also incredibly easy to construct,resulting in significant material and construction cost savings.This article analyzes the construction technology of a reinforced concrete linked arch bridge in order to achieve good construction and application.It is hoped that this analysis can provide a scientific reference for the guarantee of the construction quality and subsequent application effect of this kind of bridge.
文摘In order to ensure the construction quality and safety of small and medium span basket type steel box tied arch bridge,this paper takes a practical project as an example to analyze the key technologies in its design process.It is hoped that this analysis can provide corresponding reference for the design and construction of this kind of arch bridge.
文摘Tracking the maximum power point is a critical issue with solar systems.The power output of the solar panel varies due to variations in irradiance and temperature.Nonuniform irradiation due to partial shading conditions has a direct impact on the characteristics of photovoltaic(PV)systems.To build a diversity of maximum power point tracking algorithms in solar PV systems,this work focuses on perturb and observe,incremental conductance,and fuzzy logic control methodologies.The suggested fuzzy logic control method outperformed the conventional incremental conductance and perturb and observe algorithms with a collection of 49 rules.This paper presents a novel series-parallel-cross-tied PV array configuration with a developed fuzzy methodology.To comment on the performance of a proposed system under various partial shading conditions,a series-parallel PV array configuration has been considered.The simulation result demonstrates that the fuzzy method has a percentage improvement in the global maximum power point tracking efficiency of 24.85%when compared to the perturb and observe method and a 65.5%improvement when compared to the incremental conductance method under long wide partial shading conditions.In the case of the middle partial shading condition,the fuzzy method has a percentage improvement in the global maximum power point tracking efficiency of 12.4%compared to the perturb and observe method and a 60.7%improvement compared to the incremental conductance method.
文摘选注者言:5月24日世界卫生组织解除了香港和广州的旅游警告,同一天,香港和深圳的科学家联合声明在野生动物masked palm civets(果子狸)身上发现了与人类SARS病毒一致的病原体,人类对SARS的战斗胜利越来越近!想起5月的《科技英语学习》上第一篇文章中的一句话…the Canadian are telling them(Chinese in China Town),you dirty Chinese,you eat everything,that’S why
文摘British Prime Minister Keir Starmer’s visit to China underscores economic cooperation and strategic stability amid global uncertainties.U.K.Prime Minister Keir Starmer’s visit to China in January marks a significant shift of Britain toward a more pragmatic and stability-oriented approach in Sino-British relations.After years of political tensions and limited high-level engagement,this trip underscores London’s intent to rebuild ties based on mutual economic and strategic interests.
文摘British Prime Minister Keir Starmer’s China visit has yielded a new commitment to a long-term stable comprehensive strategic partnership,with significant breakthroughs in financial cooperation including a newly established financial working group.THE four-day visit of British Prime Minister Keir Starmer to China-the first by a U.K.Prime Minister in eight years-has marked a significant step toward stabilizing and deepening bilateral relations.
