Abstract

Fault frequency of catenary is related to meteorological conditions. In this work, based on the historical data, catenary fault frequency and weather-related fault rate are introduced to analyse the correlation between catenary faults and meteorological conditions, and further the effect of meteorological conditions on catenary operation. Moreover, machine learning is used for catenary fault prediction. As with the single decision tree, only a small number of training samples can be classified correctly by each weak classifier, the AdaBoost algorithm is adopted to adjust the weights of misclassified samples and weak classifiers, and train multiple weak classifiers. Finally, the weak classifiers are combined to construct a strong classifier, with which the final prediction result is obtained. In order to validate the prediction method, an example is provided based on the historical data from a railway bureau of China. The result shows that the mapping relation between meteorological conditions and catenary faults can be established accurately by AdaBoost algorithm. The AdaBoost algorithm can accurately predict a catenary fault if the meteorological conditions are provided. Document type: Article

Abstract

Limit state analysis of masonry arches sets to assess the safety of the structure by determining the minimum thickness that just contains a thrust line. Based on the Heymanian assumptions regarding material qualities and the equilibrium approach to the static theorem it has been explicitly proven for semi-circular arches that both the thrust line and the resulting minimum thickness value is subject to stereotomy (brick or stone laying pattern), while present study demonstrates, that the latter statement holds for pointed-circular arches as well. This is not straightforward, since the number- and arrangement of the hinges at limit state vary subject to the geometry in case of pointedcircular arches, resulting a more complex problem. It is also explicitly shown, that stereotomy might also affect the corresponding (rotational) failure mode (for certain arch geometries). Stereotomy of an existing structure is not always known, hence it is relevant to search for a stereotomy related bounding value of minimum thickness for each of the various failure modes. The potential of the envelope of resultants as a thrust line (resulting from vertical stereotomy) leading to bounding value minimum thicknesses is discussed: as shown elsewhere it bounds the family of thrust lines, hence leads to an upper bound value of minimum thickness in case of semi-circular arches. It is demonstrated however, that this cannot be generalized for other rotational failure modes which occur for circular-pointed arches. The envelope of resultants does not necessarily lead to a bounding value of minimum thickness, and even if it does, it can be either an upper or a lower bound. However, it is found that the range of minimum thickness values is bounded in all possible failure mode types. The necessary conditions are provided for each.