选择在600m^30km16个尺度上,在ArcGIS中利用常用的面积最大值法(Rule of Maximum Area,RMA)对2005年四川省1:25万土地覆被矢量数据进行栅格化,并采用两种属性精度损失评估方法:传统的常规分析方法和一种新的基于栅格单元分析方法,来对...选择在600m^30km16个尺度上,在ArcGIS中利用常用的面积最大值法(Rule of Maximum Area,RMA)对2005年四川省1:25万土地覆被矢量数据进行栅格化,并采用两种属性精度损失评估方法:传统的常规分析方法和一种新的基于栅格单元分析方法,来对比分析在这两种评估方法下RMA栅格化的属性(这里是指面积)精度损失随尺度的变化特征。结果表明:(1)在同一尺度下采用基于栅格单元方法分析所得的研究区平均属性精度损失大于常规分析方法分析得到的平均属性精度损失,且二者之间的差异在1~10km内很明显,当栅格单元大于10km时,两种方法得到的平均属性精度损失的差值稳定,且其随尺度的变化曲线趋于平行;(2)基于栅格单元分析方法不仅能够准确地定量估计RMA栅格化的属性精度损失,而且能客观地反映属性精度损失的空间分布规律;(3)对四川省1:25万土地覆被数据进行面积最大值法(RMA)栅格化的适宜尺度域最好不要超过800m,在该尺度域内数据工作量适宜,且RMA栅格化属性精度损失小于2.5%。展开更多
The reinforcement effect of a reconstruction scheme for a steel factory building was investigated using finite element method and dynamic performance test. The workshop concerned is a portal frame structure with four ...The reinforcement effect of a reconstruction scheme for a steel factory building was investigated using finite element method and dynamic performance test. The workshop concerned is a portal frame structure with four spans and two slope roofs, of which ten columns need cutting for expanding span. The design and reconstruction project of column-cut supported by joist were introduced, which includes column reinforcement, connection rebuilding between brackets and crane beams, and the changing of rigid joint into hinge joint. The construction scheme was put forward in the light of the characteristics of the reinforcement and reconstruction. Spot test of dynamic performance on the workshop and comparison with theoretical analysis results show that the column-cut supported by joist design is effective and the reconstruction project is successful.展开更多
A novel composite technique of orthogonally bonding carbon fiber-reinforced polymer （CFRP） strips and steel strips is proposed to improve the performance of reinforced concrete （RC） structures based on co-working ...A novel composite technique of orthogonally bonding carbon fiber-reinforced polymer （CFRP） strips and steel strips is proposed to improve the performance of reinforced concrete （RC） structures based on co-working of CFRP strips and steel strips. To verify the effectiveness of the method for strengthening RC two-way slabs, seven flat slabs with the dimensions of i 500 mm x 1 500 mm x 70 mm and an internal reinforcement ratio of 0.22% were prepared and tested until failure under concentrated loading, of which one was unstrengthened, one was strengthened with CFRP strips bonded to its soffit making a grid pattern （termed the CFRP grid）, and five were strengthened with a hybrid grid of CFRP strips and steel strips in two orthogonal directions （termed the CFRP-steel grid） to the bottom with steel bolt anchorage. The investigation parameters are the strengthening method, the strip spacing （150, 200, and 250 mm） and the layers of CFRP strips （one layer, two layers, and three layers of CFRP strips are applied for CFRP-steel grid）. The experimental results show that the strengthening RC two-way slabs with CFRP-steel grid are effective in delaying concrete cracking and enhancing the load-carrying capacity and deformability in comparison to the CFRP grid strengthening. The yield-line analysis model is proposed to predict the load-carrying capacity of the strengthened slabs. The prediction results are in good agreement with the experimental results.展开更多
The ventilators have been vividly called ＂the lungs of mine＂. The rotating blades are the core parts of a ventilator, they can influence the safety and reliability of the ventilator. This paper will use the tip-timi...The ventilators have been vividly called ＂the lungs of mine＂. The rotating blades are the core parts of a ventilator, they can influence the safety and reliability of the ventilator. This paper will use the tip-timing method based on the fiber Bragg grating magnetically coupling sensor to study and analyze the ventilator blade vibration, in order to realize long-distance and non-contact real-time online safety monitoring of blade vibration. Compared with the electronic sensorand fiber intensity reflective sensor, the fiber grating coupling magnetic sensor has such advantages as explosion-proof, working at harsh environment with humid air, dust and greasy dirt, capable of achieving long-distance signal transmission, and joining easily with other fiber Bragg grating sensors to form a network in order to achieve multi-parameter distributed online monitoring.展开更多
The fiber Bragg grating （FBG） sensing technology is used to dynamically monitor multiple parameters of railway switch machine poles, including time of movement, direction and quantity of loading and locking force, a...The fiber Bragg grating （FBG） sensing technology is used to dynamically monitor multiple parameters of railway switch machine poles, including time of movement, direction and quantity of loading and locking force, and states of loading resistance. This paper presents the design and implementation of a railway switch pole strain on-line monitoring system based on the FBG stress-sensibilized monitor for a Siemens S700K switch machine. The ring shape FBG strain gauge and stress-sensibilized methods significantly increased the monitoring sensitivity. Installing approaches adapted the harsh environment in the railway application. The monitoring results showed the high sensitivity and high reliability of this monitoring system. This application provides a long-term and on-line detecting method which could meet railway switch condition monitoring demands of more than 100,000 switch machines in the country.展开更多
文摘选择在600m^30km16个尺度上,在ArcGIS中利用常用的面积最大值法(Rule of Maximum Area,RMA)对2005年四川省1:25万土地覆被矢量数据进行栅格化,并采用两种属性精度损失评估方法:传统的常规分析方法和一种新的基于栅格单元分析方法,来对比分析在这两种评估方法下RMA栅格化的属性(这里是指面积)精度损失随尺度的变化特征。结果表明:(1)在同一尺度下采用基于栅格单元方法分析所得的研究区平均属性精度损失大于常规分析方法分析得到的平均属性精度损失,且二者之间的差异在1~10km内很明显,当栅格单元大于10km时,两种方法得到的平均属性精度损失的差值稳定,且其随尺度的变化曲线趋于平行;(2)基于栅格单元分析方法不仅能够准确地定量估计RMA栅格化的属性精度损失,而且能客观地反映属性精度损失的空间分布规律;(3)对四川省1:25万土地覆被数据进行面积最大值法(RMA)栅格化的适宜尺度域最好不要超过800m,在该尺度域内数据工作量适宜,且RMA栅格化属性精度损失小于2.5%。
基金Supported by Program for New Century Excellent Talents in University (No. NCET-06-0228)
文摘The reinforcement effect of a reconstruction scheme for a steel factory building was investigated using finite element method and dynamic performance test. The workshop concerned is a portal frame structure with four spans and two slope roofs, of which ten columns need cutting for expanding span. The design and reconstruction project of column-cut supported by joist were introduced, which includes column reinforcement, connection rebuilding between brackets and crane beams, and the changing of rigid joint into hinge joint. The construction scheme was put forward in the light of the characteristics of the reinforcement and reconstruction. Spot test of dynamic performance on the workshop and comparison with theoretical analysis results show that the column-cut supported by joist design is effective and the reconstruction project is successful.
基金The National Natural Science Foundation of China(No.51108355)
文摘A novel composite technique of orthogonally bonding carbon fiber-reinforced polymer （CFRP） strips and steel strips is proposed to improve the performance of reinforced concrete （RC） structures based on co-working of CFRP strips and steel strips. To verify the effectiveness of the method for strengthening RC two-way slabs, seven flat slabs with the dimensions of i 500 mm x 1 500 mm x 70 mm and an internal reinforcement ratio of 0.22% were prepared and tested until failure under concentrated loading, of which one was unstrengthened, one was strengthened with CFRP strips bonded to its soffit making a grid pattern （termed the CFRP grid）, and five were strengthened with a hybrid grid of CFRP strips and steel strips in two orthogonal directions （termed the CFRP-steel grid） to the bottom with steel bolt anchorage. The investigation parameters are the strengthening method, the strip spacing （150, 200, and 250 mm） and the layers of CFRP strips （one layer, two layers, and three layers of CFRP strips are applied for CFRP-steel grid）. The experimental results show that the strengthening RC two-way slabs with CFRP-steel grid are effective in delaying concrete cracking and enhancing the load-carrying capacity and deformability in comparison to the CFRP grid strengthening. The yield-line analysis model is proposed to predict the load-carrying capacity of the strengthened slabs. The prediction results are in good agreement with the experimental results.
文摘The ventilators have been vividly called ＂the lungs of mine＂. The rotating blades are the core parts of a ventilator, they can influence the safety and reliability of the ventilator. This paper will use the tip-timing method based on the fiber Bragg grating magnetically coupling sensor to study and analyze the ventilator blade vibration, in order to realize long-distance and non-contact real-time online safety monitoring of blade vibration. Compared with the electronic sensorand fiber intensity reflective sensor, the fiber grating coupling magnetic sensor has such advantages as explosion-proof, working at harsh environment with humid air, dust and greasy dirt, capable of achieving long-distance signal transmission, and joining easily with other fiber Bragg grating sensors to form a network in order to achieve multi-parameter distributed online monitoring.
基金The authors gratefully acknowledge the financial support of this work by the National Science Foundation of China, Numbered 61290311. Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author（s） and source are credited.
文摘The fiber Bragg grating （FBG） sensing technology is used to dynamically monitor multiple parameters of railway switch machine poles, including time of movement, direction and quantity of loading and locking force, and states of loading resistance. This paper presents the design and implementation of a railway switch pole strain on-line monitoring system based on the FBG stress-sensibilized monitor for a Siemens S700K switch machine. The ring shape FBG strain gauge and stress-sensibilized methods significantly increased the monitoring sensitivity. Installing approaches adapted the harsh environment in the railway application. The monitoring results showed the high sensitivity and high reliability of this monitoring system. This application provides a long-term and on-line detecting method which could meet railway switch condition monitoring demands of more than 100,000 switch machines in the country.
