A new intelligent anti-swing control scheme,which combined fuzzy neural network(FNN) and sliding mode control(SMC) with particle swarm optimization(PSO),was presented for bridge crane.The outputs of three fuzzy neural...A new intelligent anti-swing control scheme,which combined fuzzy neural network(FNN) and sliding mode control(SMC) with particle swarm optimization(PSO),was presented for bridge crane.The outputs of three fuzzy neural networks were used to approach the uncertainties of the positioning subsystem,lifting-rope subsystem and anti-swing subsystem.Then,the parameters of the controller were optimized with PSO to enable the system to have good dynamic performances.During the process of high-speed load hoisting and dropping,this method can not only realize the accurate position of the trolley and eliminate the sway of the load in spite of existing uncertainties,and the maximum swing angle is only ±0.1 rad,but also completely eliminate the chattering of conventional sliding mode control and improve the robustness of system.The simulation results show the correctness and validity of this method.展开更多
In this paper, Henri Lefebvre＇s theorizations about representational space and representations of space will be employed to examine Hart Crane＇s imagination of them in The Bridge. First, according to Lefebvre, repre...In this paper, Henri Lefebvre＇s theorizations about representational space and representations of space will be employed to examine Hart Crane＇s imagination of them in The Bridge. First, according to Lefebvre, representations of space are created with violence for the purpose of accumulating capital. On the other hand, representational space is directly lived or affectively felt, opened up by inhabitants＇ imagination. In addition, Lefebvre points out that in abstract space, representational space will be invaded by representations of space. In The Bridge, Crane＇s affective experience with the Brooklyn Bridge or the subway indicates that he treats New York as a representational space. Besides, Crane expresses his concern for how capitalism has encroached on it. It would seem that Crane has followed Lefebvre＇s line of thinking in The Bridge. However, it is actually a specious analysis because both the Brooklyn Bridge and the subway are representations of space. And in this long poem, Crane feels the urban space through history, which plays a key role in creating representations of space. Thus, we can conclude that Crane is actually taking ＂a walk in between＂ in The Bridge. With his imagination, Crane has combined representations of space and representational space into his own poetic vision.展开更多
Static load tests are an important means of supervising and detecting a crane＇s lift capacity. Due to space restrictions, however, there are difficulties and potential danger when testing large bridge cranes. To solv...Static load tests are an important means of supervising and detecting a crane＇s lift capacity. Due to space restrictions, however, there are difficulties and potential danger when testing large bridge cranes. To solve the loading problems of large-tonnage cranes during testing, an equivalency test is proposed based on the similarity theory and BP neural networks. The maximum stress and displacement of a large bridge crane is tested in small loads, combined with the training neural network of a similar structure crane through stress and displacement data which is collected by a physics simulation progressively loaded to a static load test load within the material scope of work. The maximum stress and displacement of a crane under a static load test load can be predicted through the relationship of stress, displacement, and load. By measuring the stress and displacement of small tonnage weights, the stress and displacement of large loads can be predicted, such as the maximum load capacity, which is 1.25 times the rated capacity. Experimental study shows that the load reduction test method can reflect the lift capacity of large bridge cranes. The load shedding predictive analysis for Sanxia 1200 t bridge crane test data indicates that when the load is 1.25 times the rated lifting capacity, the predicted displacement and actual displacement error is zero. The method solves the problem that lifting capacities are difficult to obtain and testing accidents are easily possible when 1.25 times related weight loads are tested for large tonnage cranes.展开更多
The safety brake system of metallurgy bridge crane is generally composed of two separated block brake, brake disc, and torsion shaft. The analysis of natural frequency and main vibration mode on this two-degree torsio...The safety brake system of metallurgy bridge crane is generally composed of two separated block brake, brake disc, and torsion shaft. The analysis of natural frequency and main vibration mode on this two-degree torsion vibration system is the basement to study the vibration model and vibration performance. In this work, we investigated natural frequency of the braking system of metallurgical crane with analytic method. This provides a systematic guidance towards a successful brake system design展开更多
By combining satellite tracking,land-cover extracted from Landsite 8 images,and the traditional stable isotope analysis,we studied the habitat selection and food preference of a vulnerable migratory waterbird,the Whit...By combining satellite tracking,land-cover extracted from Landsite 8 images,and the traditional stable isotope analysis,we studied the habitat selection and food preference of a vulnerable migratory waterbird,the Whitenaped Crane(Grus vipio),in one of its key stagging sites,the Shandian River Basin in the semi-arid northern China,to provide knowledge that is critical for its conservation in the Anthropocene.Our results showed that the White-naped Cranes used both uplands and natural wetlands in the stopover site.While the cranes used farmland and natural land cover equally as night-time roosting grounds,they spent most daytime foraging at farmlands.Despite the extensive usage of croplands as their foraging ground,the Bayesian mixing models based on stable isotopic analysis revealed that crop residues after harvesting,such as Maize(Zea mays)and Naked Oat(Avena chinensis),were only a small fraction of the White-naped Cranes’diet(~19%),and their diet composited mainly natural plants,such as Allium ledebourianum,Potentilla anserina,and P.tanacetifoli.Moreover,more than 20%of the total wetlands in the region were modelled as home range of the cranes.On contrast,less than 10%of croplands and about 1%of the unused uplands were identified as home range.In addition,the entire core habitats were located in natural wetlands.Our findings demonstrated the importance of natural wetlands for the survival of the threatened crane.However,the satellite-derived land cover data showed that croplands increased rapidly in the last decade in this area,at the expense of natural wetlands.With the sharp decrease of White-naped Crane population in China,the conservation of stopover sites becomes imperative.Based on our analysis,we recommend the following management actions:conserving adequate natural wetland area,regulating anthropogenic pressures such as the use of herbicides,expanding the duration and extent of current conservation regulations,establishing a comprehensive monitoring program,and initiating basin-scale ecological restoration,for effective conservation of this threatened species.These integrated conservation strategies for migratory waterbirds are necessary,considering the rapid land-cover changes and agricultural expansion that have been occurring in East Asian-Australasian Flyway,especially in the semi-arid temperate zone.展开更多
基金Project(51075289) supported by the National Natural Science Foundation of ChinaProject(20122014) supported by the Doctor Foundation of Taiyuan University of Science and Technology,China
文摘A new intelligent anti-swing control scheme,which combined fuzzy neural network(FNN) and sliding mode control(SMC) with particle swarm optimization(PSO),was presented for bridge crane.The outputs of three fuzzy neural networks were used to approach the uncertainties of the positioning subsystem,lifting-rope subsystem and anti-swing subsystem.Then,the parameters of the controller were optimized with PSO to enable the system to have good dynamic performances.During the process of high-speed load hoisting and dropping,this method can not only realize the accurate position of the trolley and eliminate the sway of the load in spite of existing uncertainties,and the maximum swing angle is only ±0.1 rad,but also completely eliminate the chattering of conventional sliding mode control and improve the robustness of system.The simulation results show the correctness and validity of this method.
文摘In this paper, Henri Lefebvre＇s theorizations about representational space and representations of space will be employed to examine Hart Crane＇s imagination of them in The Bridge. First, according to Lefebvre, representations of space are created with violence for the purpose of accumulating capital. On the other hand, representational space is directly lived or affectively felt, opened up by inhabitants＇ imagination. In addition, Lefebvre points out that in abstract space, representational space will be invaded by representations of space. In The Bridge, Crane＇s affective experience with the Brooklyn Bridge or the subway indicates that he treats New York as a representational space. Besides, Crane expresses his concern for how capitalism has encroached on it. It would seem that Crane has followed Lefebvre＇s line of thinking in The Bridge. However, it is actually a specious analysis because both the Brooklyn Bridge and the subway are representations of space. And in this long poem, Crane feels the urban space through history, which plays a key role in creating representations of space. Thus, we can conclude that Crane is actually taking ＂a walk in between＂ in The Bridge. With his imagination, Crane has combined representations of space and representational space into his own poetic vision.
基金Supported by National "Twelfth Five-Year" Plan for Science&Technology Support of China(Grant No.2011BAK06B05)National High-tech Research and Development Program of China(863 Program,Grant No.2013AA040203)Shanxi Scholarship Council of China(Grant No.2015-088)
文摘Static load tests are an important means of supervising and detecting a crane＇s lift capacity. Due to space restrictions, however, there are difficulties and potential danger when testing large bridge cranes. To solve the loading problems of large-tonnage cranes during testing, an equivalency test is proposed based on the similarity theory and BP neural networks. The maximum stress and displacement of a large bridge crane is tested in small loads, combined with the training neural network of a similar structure crane through stress and displacement data which is collected by a physics simulation progressively loaded to a static load test load within the material scope of work. The maximum stress and displacement of a crane under a static load test load can be predicted through the relationship of stress, displacement, and load. By measuring the stress and displacement of small tonnage weights, the stress and displacement of large loads can be predicted, such as the maximum load capacity, which is 1.25 times the rated capacity. Experimental study shows that the load reduction test method can reflect the lift capacity of large bridge cranes. The load shedding predictive analysis for Sanxia 1200 t bridge crane test data indicates that when the load is 1.25 times the rated lifting capacity, the predicted displacement and actual displacement error is zero. The method solves the problem that lifting capacities are difficult to obtain and testing accidents are easily possible when 1.25 times related weight loads are tested for large tonnage cranes.
文摘The safety brake system of metallurgy bridge crane is generally composed of two separated block brake, brake disc, and torsion shaft. The analysis of natural frequency and main vibration mode on this two-degree torsion vibration system is the basement to study the vibration model and vibration performance. In this work, we investigated natural frequency of the braking system of metallurgical crane with analytic method. This provides a systematic guidance towards a successful brake system design
基金This research was funded by National Natural Science Foundation of China(No.31971400)the Fundamental Research Funds for the Central Universities(No.BLX202144).
文摘By combining satellite tracking,land-cover extracted from Landsite 8 images,and the traditional stable isotope analysis,we studied the habitat selection and food preference of a vulnerable migratory waterbird,the Whitenaped Crane(Grus vipio),in one of its key stagging sites,the Shandian River Basin in the semi-arid northern China,to provide knowledge that is critical for its conservation in the Anthropocene.Our results showed that the White-naped Cranes used both uplands and natural wetlands in the stopover site.While the cranes used farmland and natural land cover equally as night-time roosting grounds,they spent most daytime foraging at farmlands.Despite the extensive usage of croplands as their foraging ground,the Bayesian mixing models based on stable isotopic analysis revealed that crop residues after harvesting,such as Maize(Zea mays)and Naked Oat(Avena chinensis),were only a small fraction of the White-naped Cranes’diet(~19%),and their diet composited mainly natural plants,such as Allium ledebourianum,Potentilla anserina,and P.tanacetifoli.Moreover,more than 20%of the total wetlands in the region were modelled as home range of the cranes.On contrast,less than 10%of croplands and about 1%of the unused uplands were identified as home range.In addition,the entire core habitats were located in natural wetlands.Our findings demonstrated the importance of natural wetlands for the survival of the threatened crane.However,the satellite-derived land cover data showed that croplands increased rapidly in the last decade in this area,at the expense of natural wetlands.With the sharp decrease of White-naped Crane population in China,the conservation of stopover sites becomes imperative.Based on our analysis,we recommend the following management actions:conserving adequate natural wetland area,regulating anthropogenic pressures such as the use of herbicides,expanding the duration and extent of current conservation regulations,establishing a comprehensive monitoring program,and initiating basin-scale ecological restoration,for effective conservation of this threatened species.These integrated conservation strategies for migratory waterbirds are necessary,considering the rapid land-cover changes and agricultural expansion that have been occurring in East Asian-Australasian Flyway,especially in the semi-arid temperate zone.
