Active Vibration-Based Condition Monitoring of a Transmission Line

In the power system, the transmission tower is located in a variety of terrains. Sometimes there will be displacement, inclination, settlement and other phenomena, which eventually lead to the collapse of the tower. In this paper, a method for monitoring the settlement of a transmission tower based on active vibration response is proposed, which is based on the principle of modal identification. Firstly, a device was designed, which includes three parts: a monitoring host, wireless sensor and excitation device. It can tap the transmission tower independently and regularly, and collect the vibration response of the transmission tower. Then, vibration analysis experiments were used to validate the horizontal vibration responses of transmission towers which can be obtained by striking the transmission towers from either the X direction or Y direction. It can be seen from the frequency response function that the natural frequencies obtained from these two directions are identical. Finally, the transmission tower settlement experiment was carried out. The experimental results show that the third to fifth natural frequencies decreased most obviously, even up to 2.83 Hz. Further, it was found that under different conditions, as long as the tower legs adjacent to the excitation position settle, the natural frequency will decrease more significantly, which is very helpful for engineering application.

Host plant preference of Trioza erytreae on lemon and bitter orange plants

Trioza erytreae, the African citrus psyllid, is a vector of Candidatus Liberibacter spp., the causal agent of the citrus greening disease or Huanglongbing (HLB). The spread of the vector throughout the Iberian Peninsula has been continuous since its introduction in mainland Spain in 2014. The patterns of host preference and feeding behaviour largely depend on olfactory cues. Understanding these patterns is crucial to prevent further dispersion and develop management measures against the pest. In this work, a series of settlement, olfactometric, probing, and feeding experiments were conducted to assess the host preference of T. erytreae for lemon or bitter orange plants. The settlement experiment provided evidence on the preference of both sexes of T. erytreae for lemon plants, whereas males did not show any significant choice pattern in the case of the olfactometric assays. Forty EPG variables were analysed to describe and compare the probing and feeding behaviour of T. erytreae on lemon and bitter orange plants. The EPG variables indicated that T. erytreae has some difficulties in accepting the phloem of bitter orange plants. This suggests that lemon plants would be a better source for the acquisition of Candidatus Liberibacter asiaticus (CLas) by T. erytreae since the psyllid spends much longer periods feeding from the phloem on lemon than on bitter orange.

Study on the Settlement Experiment of Iron Tailings

The settlement experiment of representative iron tailings was studied, the iron tailings were from a processing plant of Wuhan Iron and Steel Group. There were four experiments were conducted which includes nature sedimentation test, coagulation sedimentation test of inorganic salt coagulant, flocculation sedimentation test of polymer flocculant and the mix coagulation sedimentation test. The test results showed that the size of sample is relatively fine and unevenly distributed, what's more, the velocity of natural sediment is very slow, and the effect that concentration has on the settling velocity of particles is obvious. The inorganic salt coagulant could reduce turbidity of supernatant, but it play a limited role in improving settling rate, it was found that FeCl3 is the best coagulation agent, PAM is effective flocculant for the sample, and the coagulation effect of cationic flocculation (molecular weight is six million) is better than that of anionic and nonionic. The settling velocity of particles was improved and the solid content of supernatant was reduced in the mix coagulation sedimentation test, but the improvement of settling velocity was not obvious. The author suggests that the single cationic polyacrylamide flocculant which was used for pretreatment on the tailings could meet the requirement of the tailings settlement.