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A modified damage index probability imaging algorithm based on delay-and-sum imaging for synthesizing time-reversed Lamb waves
Get PDFImaging for damage in plate structure by Lamb waves is one of the most effective methods in the field of structural health monitoring. In order to improve the accuracy of damage localization, a novel method is proposed to modify damage exponent probability imaging algorithm based on delay-and-sum imaging by using time reversal Lamb waves. A new probability distribution function is introduced to improve the damage index probability method and is combined with delay-and-sum method for damage localization. Experimental results on aluminum plate show that the hybrid algorithm achieves better accuracy of damage location and imaging quality than the conventional delay-and-sum method
Experimental determination on the critical angle of seismic incidence of curved bridge
Get PDFThe shaking table model test mainly focuses on the study of seismic response law, aseismic performance and seismic damping and isolation effect of bridges with a single or multi-platform shaking table. Basically, the plane principal axis direction is adopted for the seismic input of structural models. Little research effort considering multi-angle seismic input has been reported in the structural model test. In this paper we designed and conducted a small-scale shaking table model test to study the seismic response law of the curved girder bridges with seismic input at different angles, and provided experimental verification for the theoretical method of the most unfavorable angle of seismic input. The experimental results show that the variation trend of component response to variation of the seismic input direction is consistent with that of the numerical analysis, which indicates that the designed device is effective
Stability of stope structure under different mining methods
Get PDFThe ore body has a great influence on the stability of surrounding rock and mining safety under different mining modes, and the reasonable selection of mining mode depends on other characteristics, such as ore structure surface feature, rock mass mechanical property, and ground stress distribution. Given the insufficient mining research data, this study establishes a 3D model by using the FLAC3D calculation program. Through numerical simulation and other technical means, a preliminary study on plastic and minimum stress changes during horizontal pillar mining, stress changes under different mining modes, and the effect comparison of full filling mining modes is conducted. Results show that the surrounding rock at the corner of pillar 1 is damaged, the plastic zone decreases, and the minimum stress in each working procedure increases slightly. The area of the plastic zone in alternate mining is smaller to that in continuous mining. This study provides a theoretical basis for ore body mining
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
Parametric design and analysis of a mortar base plate
Get PDFIn order to improve the efficiency of designing and analyzing a mortar base plate, parametric technology has been applied to the design and analysis of the base plate. By conducting characteristic analysis of the base plate, critical design parameters extracted have been driven as characteristics to perform secondary development on UG, so that the base plate could be automatically modeled in three dimensions. Meanwhile, Python has also been applied in the secondary development of Abaqus, so as to realize the automatic finite element modeling of the base plate. After conducting parametric analysis on the model established, sensitivities of design variables of the base plate have been analyzed using an approximate model in combination with the sample designed by the optimal Latin hypercube approach. Moreover, parametric optimization carrying out on results of sensitivity analysis could give feedback to parametric design for guiding parameter values of design variables to improve the design qualit
Computational fluid dynamics analysis and experimental validation of solar panel cleaning mechanism
Get PDFSolar energy is one of the widely used non-conventional form of energy. photo voltaic panels generate electricity and heat by absorbing solar irradiation. The performance of solar panels depends on several factors like dust accumulation on the surface, solar cell temperature, angle of inclination etc., To perform the cleaning action efficiently a semi-automatic cleaning mechanism has been designed and fabricated. The designed experimental setup consists of several nozzles attached on top of the solar panels and water is supplied to each nozzle using a Poly Vinyl Chloride (PVC) pipe frame connected to an AC motor operated with a time switch. Water flows on the surface of photo voltaic module, thus heat exchange takes place. One dimensional heat transfer analysis is performed and the results are compared to the experimental results for validation. The experiments were conducted at Bennett University, Greater Noida dated 9 October to 16 October. An increase in efficiency by 1.28 % to 2.65 % was reported in this experimental study
Graphical PID tuning method for uncertain fractional-order multivariable systems
Get PDFIn this paper, a graphical tuning method for controllers parameters based on the open-loop fractional transfer function (FO-EOTF) method is proposed for fractional-order parameter uncertain multivariable system. The FO-EOTF method is proposed to transform the parameter uncertain fractional-order multivariable system into a set of independent parameter uncertain fractional-order univariate systems and determine the parameters regions of the univariate systems. The gain phase margin tester is used to further guarantee the robust performance of the controlled system. Finally, simulation result from the numerical simulation is presented to demonstrate the effectiveness of this method
Path tracking with minimum time of vehicle handling inverse dynamics based on adaptive gauss pseudospectral method
Get PDFVehicle driving safety is the urgent key problem to be solved by an independent automobile development project. And it is also the premise and one of the necessary conditions for active vehicle safety. A new technique for path tracking with minimum time of vehicle handling inverse dynamics is proposed in this paper. Based on a new optimal control method – Adaptive Gauss Pseudospectral Method (AGPM), the optimal control for path tracking with minimum time problem was converted into a nonlinear programming problem which met the boundary condition and a series of path constraints including path constraint, state constraint, control constraint. And then the problem was solved using the sequential quadratic programming (SQP). The simulation results showed that the proposed method was not sensitive to the initial value and the optimization efficiency was higher compared with indirect methods and traditional direct methods. When solving the problem of path tracking with minimum time as per this method, boundary constraints and path constraints were well satisfied. The algorithm was not only precise but it could also shorten the evaluation period of vehicle handling stability and could reduce the tremendous cost for real vehicle testing. So the maneuverability of two different vehicles that complete the pylon course slalom test road with minimum time can be evaluated objectively by utilizing the method. The model correctness is verified through a real vehicle test
Mini review: interactions between antifungal azoles, neurological bladder and urinary problems
Get PDFThis review describes the importance of antifungal drugs in medicinal, pharmaceutical and agriculture fields because of their wide spectrum of biological activities in the recent years. Their chemical structure has expected considerable interest. Also, we focus on urinary problems and can be helpful to develop the ideas in neurological bladder for see the interactions and effect of antifungal drugs in system neurologic, because urinary tract infection is one of the most frequent diseases in medical practice. Some definitions are discussed and reported emphasizing microbiological, clinical and therapeutic aspects
Dynamical processes in a multi-motor gear drive of heavy slabbing mill
Get PDFA real case study is represented of abrupt failures in a new multi-motor gear drive of vertical rolls in the heavy slabbing mill. Modal analysis is conducted, and the lowest torsional vibration modes are verified by the data from an industrial plant. Conditions of parametric resonances due to variable stiffness of teeth are determined within the range of working speed. The branched gear drive is investigated by the non-linear dynamical model with backlashes. It is shown that instantaneous dynamic loads in driveline are strongly dependent on the difference in gap sizes and phase shift between two intermediate gears in the output gear wheel coupling. Deviation in electrical parameters by 0.5 % is considered as the additional cause of not equal load sharing of parallel motors. Results of this research allowed preventing further failures of the gearbox and optimizing slabbing mill control. The proposed approach can be used in other multi-motor machines