在带电作业实训项目中,作业人员进出电场需要保持正确的姿态,以保证自身的组合间隙小于最小组合间隙,避免引起安全事故,传统的带电作业培训中主要依靠现场教练的主观经验判断作业人员的实时组合间隙,判断的标准具有较强的主观性,从而导...在带电作业实训项目中,作业人员进出电场需要保持正确的姿态,以保证自身的组合间隙小于最小组合间隙,避免引起安全事故,传统的带电作业培训中主要依靠现场教练的主观经验判断作业人员的实时组合间隙,判断的标准具有较强的主观性,从而导致一定的安全隐患。文中针对现有问题,创新性的提出了一种基于视频的智能检测算法,运用了自适应混合高斯背景建模、团块检测、前景融合等模式识别算法。该算法以500 k V输电线塔架为实验对象,实验表明该算法能够准确检测出作业人员的实时组合间隙,并在发生违规操作时,可及时准确的给予警示,有助于规范作业人员的操作,可有效提高带电作业的安全系数。展开更多
A nanocomposite electrocatalyst was prepared with the method of cluster beam deposition of palladium nanoparticle thin lms on carbon nanoparticle supporting layers and used as sensitive nonenzyme hydrogen peroxide sen...A nanocomposite electrocatalyst was prepared with the method of cluster beam deposition of palladium nanoparticle thin lms on carbon nanoparticle supporting layers and used as sensitive nonenzyme hydrogen peroxide sensors. An enhancement on the electrocatalytic activity of the palladium nanoparticles toward H2O2 reduction was observed, which was related to the coverage of the carbon nanoparticles. With one monolayer of carbon nanoparticles, the H2O2 detection sensitivity reached the maximum, which was more than twice of that of the pure Pd nanoparticles.展开更多
After the declaration of the first case of Legionnaire's disease in Cameroon in 2007, the Centre Pasteur of Cameroon implemented the detection method for Legionella. The introduction of this new method was put in pla...After the declaration of the first case of Legionnaire's disease in Cameroon in 2007, the Centre Pasteur of Cameroon implemented the detection method for Legionella. The introduction of this new method was put in places in order to investigate Legionella spp. colonization of water distribution systems (WDS) of large buildings including hospitals, hotels and Off Shore Exploitations Sites (OSES) in an attempt to identify risk factors for Legionella spp. Water systems of 6 hotels, 6 hospitals and 6 ships were investigated for the presence of Legionella spp.. A total of 130 samples were collected, 77 from hotels, 27 from hospitals and 26 from ships. 51 Legionella spp. were isolated from 41 (31.54%) water samples. Of a total of 51 positive isolates, 40/51 (78.4%) were L. pneumophila with 21 (52.5%) Legionellapneumophila serogroup (sg) 1, 16 (40%) L. pneumophila sg 5, 2 (5%) L. pneumophila sg 6, 1 (2.5%) L. pneumophila sg 7 and 11/51 Legionella spp. with 10 (90%) L. anisa, 1 (10%) Legionella dumoffii. 5 L. pneumophila sg 1 were associated with 5 L. pneumophila sg 5 and 4 L. pneumophila sg 1 were associated with 4 L. anisa. These results showed that WDS of hospitals, hotels and ships can be heavily colonized by Legionella spp. and may present a risk of Legionnaires' disease. Based on these preliminary results, we have just put in place a Legionella survey protocol in Cameroon.展开更多
Two definitions are given that Definitionl: an induced subgraph by a vertex vie G and its neighbors in G is defined as a vertex adjacent closed subgraph, and denoted by Qi (=G[V(Nvi)]), with the vertex vi called ...Two definitions are given that Definitionl: an induced subgraph by a vertex vie G and its neighbors in G is defined as a vertex adjacent closed subgraph, and denoted by Qi (=G[V(Nvi)]), with the vertex vi called the hub; and Definition2: A r(k,I)-I vertices graph is called the (k,l)-Ramsey graph, denoted by RG(k,1), if RG(k,1) only contains cliques Kk.1 and the intersect QiNQj of any two nonadjacent vertices vi and vj of RG(k,I) contains only Kk-2. Meanwhile, the RG(k,l)'s complement RG(I,k) contains only cliques Kl.l, and the intersect QiNQj of any two nonadjacent vertices vi and vj of RG(I,k) contains only Ki.2. On the basis of those definitions, two theorems are put forward and proved in this paper. They are Theoreml: the biggest clique in G is contained in some Qi of G, and Theorem 2: r(k,1) = [V(RG(k,I))I + 1. With those definitions and theorems as well as analysis of chord property, a method for quick inspection and building RG(k,1) is proposed. Accordingly, RG(4,6) is built, it is a strongly 14-regular graph on order 35. We have tested RG(4,6) and its complement, as a result, they meet the defintion2, so we proclaim that r(4,6)=36.展开更多
The aim of this paper is to investigate the damage cracking characteristics of rock and soil aggregate(RSA)by X-ray computed tomography(CT)under uniaxial compressive loading.The mean CT value for the region of interes...The aim of this paper is to investigate the damage cracking characteristics of rock and soil aggregate(RSA)by X-ray computed tomography(CT)under uniaxial compressive loading.The mean CT value for the region of interest(ROI)is used to analyze the cracking characteristics.Also,the mathematical morphology method based on the image threshold segmentation is used to obtain characteristic parameters of cracks to describe the cracking evolution of RSA.Results show that the elastic mismatch between rock blocks and soil matrix is the primary reason for RSA cracking.The mean CT value for the RSA specimen,rock block inclusions,and their adjacent soil regions decreases with the increasing stress level.However,it is more sensitive for block inclusions than soil regions.Using the image segmentation method,length,area and mean width of cracks obey to power function distribution.Crack statistical characteristics are closely related to the rock block’s distribution and morphology.These results may be useful to reveal the mesoscopic cracking mechanism,establish meso-damage evolution equation,and constitutive relation for RSA.展开更多
文摘在带电作业实训项目中,作业人员进出电场需要保持正确的姿态,以保证自身的组合间隙小于最小组合间隙,避免引起安全事故,传统的带电作业培训中主要依靠现场教练的主观经验判断作业人员的实时组合间隙,判断的标准具有较强的主观性,从而导致一定的安全隐患。文中针对现有问题,创新性的提出了一种基于视频的智能检测算法,运用了自适应混合高斯背景建模、团块检测、前景融合等模式识别算法。该算法以500 k V输电线塔架为实验对象,实验表明该算法能够准确检测出作业人员的实时组合间隙,并在发生违规操作时,可及时准确的给予警示,有助于规范作业人员的操作,可有效提高带电作业的安全系数。
基金supported by the National Natural Science Foundation of China(No.11627806 and No.61301015)supported by a Project funded by the Priority Academic Programme Development of Jiangsu Higher Education Institutions
文摘A nanocomposite electrocatalyst was prepared with the method of cluster beam deposition of palladium nanoparticle thin lms on carbon nanoparticle supporting layers and used as sensitive nonenzyme hydrogen peroxide sensors. An enhancement on the electrocatalytic activity of the palladium nanoparticles toward H2O2 reduction was observed, which was related to the coverage of the carbon nanoparticles. With one monolayer of carbon nanoparticles, the H2O2 detection sensitivity reached the maximum, which was more than twice of that of the pure Pd nanoparticles.
文摘After the declaration of the first case of Legionnaire's disease in Cameroon in 2007, the Centre Pasteur of Cameroon implemented the detection method for Legionella. The introduction of this new method was put in places in order to investigate Legionella spp. colonization of water distribution systems (WDS) of large buildings including hospitals, hotels and Off Shore Exploitations Sites (OSES) in an attempt to identify risk factors for Legionella spp. Water systems of 6 hotels, 6 hospitals and 6 ships were investigated for the presence of Legionella spp.. A total of 130 samples were collected, 77 from hotels, 27 from hospitals and 26 from ships. 51 Legionella spp. were isolated from 41 (31.54%) water samples. Of a total of 51 positive isolates, 40/51 (78.4%) were L. pneumophila with 21 (52.5%) Legionellapneumophila serogroup (sg) 1, 16 (40%) L. pneumophila sg 5, 2 (5%) L. pneumophila sg 6, 1 (2.5%) L. pneumophila sg 7 and 11/51 Legionella spp. with 10 (90%) L. anisa, 1 (10%) Legionella dumoffii. 5 L. pneumophila sg 1 were associated with 5 L. pneumophila sg 5 and 4 L. pneumophila sg 1 were associated with 4 L. anisa. These results showed that WDS of hospitals, hotels and ships can be heavily colonized by Legionella spp. and may present a risk of Legionnaires' disease. Based on these preliminary results, we have just put in place a Legionella survey protocol in Cameroon.
文摘Two definitions are given that Definitionl: an induced subgraph by a vertex vie G and its neighbors in G is defined as a vertex adjacent closed subgraph, and denoted by Qi (=G[V(Nvi)]), with the vertex vi called the hub; and Definition2: A r(k,I)-I vertices graph is called the (k,l)-Ramsey graph, denoted by RG(k,1), if RG(k,1) only contains cliques Kk.1 and the intersect QiNQj of any two nonadjacent vertices vi and vj of RG(k,I) contains only Kk-2. Meanwhile, the RG(k,l)'s complement RG(I,k) contains only cliques Kl.l, and the intersect QiNQj of any two nonadjacent vertices vi and vj of RG(I,k) contains only Ki.2. On the basis of those definitions, two theorems are put forward and proved in this paper. They are Theoreml: the biggest clique in G is contained in some Qi of G, and Theorem 2: r(k,1) = [V(RG(k,I))I + 1. With those definitions and theorems as well as analysis of chord property, a method for quick inspection and building RG(k,1) is proposed. Accordingly, RG(4,6) is built, it is a strongly 14-regular graph on order 35. We have tested RG(4,6) and its complement, as a result, they meet the defintion2, so we proclaim that r(4,6)=36.
基金supported by the National Natural Science Foundation of China(Grants Nos.41227901,41027001,and 41027001)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grants Nos.XDB10030000,XDB10030300 and XDB10050400)
文摘The aim of this paper is to investigate the damage cracking characteristics of rock and soil aggregate(RSA)by X-ray computed tomography(CT)under uniaxial compressive loading.The mean CT value for the region of interest(ROI)is used to analyze the cracking characteristics.Also,the mathematical morphology method based on the image threshold segmentation is used to obtain characteristic parameters of cracks to describe the cracking evolution of RSA.Results show that the elastic mismatch between rock blocks and soil matrix is the primary reason for RSA cracking.The mean CT value for the RSA specimen,rock block inclusions,and their adjacent soil regions decreases with the increasing stress level.However,it is more sensitive for block inclusions than soil regions.Using the image segmentation method,length,area and mean width of cracks obey to power function distribution.Crack statistical characteristics are closely related to the rock block’s distribution and morphology.These results may be useful to reveal the mesoscopic cracking mechanism,establish meso-damage evolution equation,and constitutive relation for RSA.