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
In order to find landscape plants purifying Pb pollution of soil,a pot experiment was conducted to study Pb resistance and enrichment characteristics of six species of Compositae plants( Aster ageratoides,Rudbeckia hi...In order to find landscape plants purifying Pb pollution of soil,a pot experiment was conducted to study Pb resistance and enrichment characteristics of six species of Compositae plants( Aster ageratoides,Rudbeckia hirta,Cosmos sulphureus,Gynura bicolor,Calendula officinalis,Bidens pilosa) in different soil Pb concentrations. The results showed that the dry weight of aboveground part in the six plants decreased with the increase of soil Pb concentration. The tolerance index( TI) of C. sulphureus,G. bicolor and C. officinalis was greater than 0. 5 in all concentrations,and the root tolerance index( RTI) was greater than 0. 9,which were better resistant to Pb stress. The maximum Pb content in aboveground part of R. hirta was 1 783 mg/kg,and the enrichment and transport coefficients were all greater than 1. When the soil Pb concentration was 500 mg/kg,the total Pb accumulation in the aboveground part of R. hirta was 2. 507 mg/plant. Finally based on the integrated observation of the enrichment coefficient,transport factor and repair potential index,it believed that R. hirta can be used to restore Pb contaminated soil at low concentration.展开更多
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.
基金Supported by Science and Technology Support Project in Guizhou Province(Qiankehezhicheng[2017]2580)Key Projects of Guizhou Science and Technology Fund(Qiankehe JZ[2014]2012)
文摘In order to find landscape plants purifying Pb pollution of soil,a pot experiment was conducted to study Pb resistance and enrichment characteristics of six species of Compositae plants( Aster ageratoides,Rudbeckia hirta,Cosmos sulphureus,Gynura bicolor,Calendula officinalis,Bidens pilosa) in different soil Pb concentrations. The results showed that the dry weight of aboveground part in the six plants decreased with the increase of soil Pb concentration. The tolerance index( TI) of C. sulphureus,G. bicolor and C. officinalis was greater than 0. 5 in all concentrations,and the root tolerance index( RTI) was greater than 0. 9,which were better resistant to Pb stress. The maximum Pb content in aboveground part of R. hirta was 1 783 mg/kg,and the enrichment and transport coefficients were all greater than 1. When the soil Pb concentration was 500 mg/kg,the total Pb accumulation in the aboveground part of R. hirta was 2. 507 mg/plant. Finally based on the integrated observation of the enrichment coefficient,transport factor and repair potential index,it believed that R. hirta can be used to restore Pb contaminated soil at low concentration.
