Maintenance, Reliability and Condition Monitoring
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Investigation and optimization of the cable force of a combined highway and railway steel truss cable-stayed bridge in completion state
Get PDFIn order to study the reasonable cable force of a highway and rail dual-purpose steel truss cable-stayed bridge in the completion state, this paper employs four methods, i.e. the rigid supported continuous beam method, bending minimum energy method, influence matrix method and BP neural network method combined with a genetic algorithm. The Baijusi Yangtze river bridge, with a main span of 660 m in the completion state, is chosen as the object of study. Through comparative analysis, it is found that the rigid supported continuous beam combined with the influence matrix method can determine the reasonable cable force of the highway and rail dual-purpose steel truss cable-stayed bridge more quickly and effectively
Design study of a magnetoelectric-electromagnetic vibration energy converter for energy harvesting
Get PDFThe aim of this paper is to design a combination of a magnetoelectric-electromagnetic (ME-EM) vibration converter in order to reach an improved energy outcome. In this paper, the influence of magnets polarization and magnetoelectric transducer and coil direction are investigated. For this purpose, a finite element model is developed using one coil, one ME transducer in a magnetic circuit. Simulation results show that a better magnetic field distribution and variation is reached, if the magnetic circuit magnets are placed in attraction. Radial polarization shows decisive advantages in comparison with axial polarization. The placement of coil parallel to the magnetic circuit direction and the magnetization of the ME transducer along its width is the optimal direction relative to the magnetic circuit
Identification and location of ship pipeline leakage based on VMD
Get PDFPipeline plays an important role in various systems of the ship. However, due to the harsh environment, leakage often occurs in ship pipeline. This paper proposes a method to identity and locate the pipeline leakage. Using the variational mode decomposition (VMD) algorithm, the vibration signal is decomposed into band-limited intrinsic mode functions (BIMFs). The effective BIMFs are then selected by the correlation coefficient. Center frequency and energy value of the effective BIMFs are extracted as feature vector. Radial Basis Function (RBF) neural network is then used as a tool to identify and locate the leakage. The proposed method is finally verified by experiments
Level set medical image segmentation aided by cooperative quantum particle optimization with Lévy flights
Get PDFImage segmentation plays an important part of image processing, and is also the premise and basis of image analysis and image understanding and recognition. Among the level set based methods, the original Local Binary Fitting (LBF) algorithm is a successful deterministic algorithm that suffers from sensitization to size of the local minimum, image contours, shapes, and initial positions. Among them, Level Set method promotes the two-dimensional problem to the three-dimensional one and then solves it using implicit method to express closed curve of plane. In this article, a novel Level Set model aided by PSO was proposed to solve automated medical image segmentation. The experimental result of segmentations on the benchmark shows that our proposed method is effective to both simple and complex medical images
Effects of the wide-body suspension bridge auxiliary structure on flutter characteristics by CFD
Get PDFThis paper is focused on the CFD numerical simulation of flutter characteristics of the wide-body flat steel box girder of Chongqing Cuntan Yangtze Bridge. The specific influence on the aerodynamic performance and flutter critical wind velocity have been studied by setting different railing ventilation rates. The results show that: the subsidiary structures of the main beam have an adverse effect on the stability of bridge flutter. The ventilation rate of the railings affects the flutter derivatives and the critical wind speed of the flutter
Economic benefit analysis of low-level high vacuum compaction method from the perspective of low carbon
Get PDFIn order to discuss the superiorities of High Vacuum Drubbing Means (HVDM) in soft foundation treatment of roads, this paper takes the soft foundation treatment project of Wucheng Road in Wuwei County of Wanjiang City Belt in China as an example. By comparing and analyzing the economic benefit differences between HVDM method and traditional powder injection pile method in soft soil foundation treatment, the following conclusions are drawn: Low-level high-vacuum compaction method soft base processing method is better than traditional powder-jet pile method in soft foundation treatment. The method can better reduce the consumption of raw materials such as cement and stone, avoid the pollution of the social environment caused by cement production, shorten the construction period by about 50 % and save the direct labor cost. Compared with the traditional powder-sprayed pile method, total cost of the project can be saved by more than 30 % and the construction quality is controllable. The construction process is green and its social and economic benefits are remarkable
Fault diagnosis method for energy storage mechanism of high voltage circuit breaker based on CNN characteristic matrix constructed by sound-vibration signal
Get PDFAiming at the problem that some traditional high voltage circuit breaker fault diagnosis methods were over-dependent on subjective experience, the accuracy was not very high and the generalization ability was poor, a fault diagnosis method for energy storage mechanism of high voltage circuit breaker, which based on Convolutional Neural Network (CNN) characteristic matrix constructed by sound-vibration signal ,was proposed. In this paper, firstly, the morphological filtering was used for background noise cancellation of sound signal, and the time scale alignment method based on kurtosis and envelope similarity were proposed to ensure the synchronism of the sound-vibration signal. Secondly, the Pearson correlation coefficient was used to construct two-dimensional image characteristic matrix for the expanded sound-vibration signal. Finally, the characteristic matrix was trained by utilizing CNN. Local Response Normalization (LRN) and core function decorrelation were utilized to improve the structure of CNN model, which reduced the bad impact of large data fluctuation of energy storage process on the diagnostic accuracy of circuit breaker energy storage mechanism. Compared with the traditional method, the proposed method has obvious advantages, whose total accurate rate up to 98.2 % and generalization performance is excellent
Earthquake damage on the vaulted nave of the Atlatlahucan Ex-Convent church in Morelos, Mexico
Get PDFThe State of Morelos, in Mexico, has an architectural heritage conformed by 4614 religious and civil buildings, many of which were severely affected by the earthquake that occurred on September 19, 2017, which also caused damages to the built heritage in the states of Puebla, Tlaxcala, Mexico and Mexico City. A total of about 2800 heritage buildings suffered different damages degrees, reaching in many cases the collapse of elements such as vaults, domes, bell towers as well as their cloisters. The Ex-Convent of San Mateo in Atlatlahucan, Morelos, suffered damages on its main nave, in the pinnacles on the longitudinal side walls as well as in the clock box located on the front façade. In the present work, an analysis is made of the damages observed in the building, as well as a preliminary analytical diagnosis of the behavior of the main nave in order to propose future reinforcement actions for the building
The influence of ferromagnetic fluids on performance of hydrodynamic bearings
Get PDFThe rotors are often mounted in hydrodynamic bearings. To achieve their optimum performance in a wide range of operating speeds, their stiffness and damping parameters must be adaptable to the current angular velocity. This is offered by application of smart fluids sensitive to a magnetic field. The detailed analysis shows that application of ferromagnetic fluids is possible only for small sliding bearings. For bearings, the operation of which requires to generate high pressure, this concept fails. This arrived at the idea to use the ferrofluids-based magnetorheological fluids as a lubricant. This paper deals with the development of a basic concept of such a bearing and with the principle considerations on the magnetic flux generation and its propagation in the bearing housing and the lubricating layer. The developed mathematical model of the bearing was applied for investigation of the influence of changes of the lubricant properties by means of a magnetic field on the vibration attenuation of a rigid rotor excited by unbalance. The pressure distribution in the bearing gap is governed by the Reynolds equation adapted to non-Newtonian lubricant, the yielding shear stress of which depends of magnetic induction. The magnetic flux propagation in the bearing housing is described by the Hopkinson law. The results of the simulations show that the increase of the yielding shear stress of the lubricant by action of a magnetic field rises the bearing load capacity and does not destabilize the rotor vibration
Simulation of elastic wave transmission in phononic crystal waveguides
Get PDFAn atomistic Green’s function method hybrid with the finite element method is developed to analyze the mode-dependent elastic wave transmittance in a structure with arbitrary geometries. The validity of the proposed method is demonstrated by the phononic crystal waveguide case and a comparison with the transfer matrix method. This method also can be used to investigate the phonon ballistic transport in a quantum system at low temperatures