Advanced Materials Research Vols. 706-708

Abstract: A successful prediction that whether a compressor blade is able to overcome the resonance fatigue and fatigue life of forced vibration is based on its harmonic response analysis.Hard coatings with metal or ceramic substrate are effective to change the natural characteristics and vibration amplitude of a compressor blade so that to improve the anti-vibration fatigue capability. In this paper, modal analysis and harmonic response analysis based on the finite element method are achieved to investigate the contributions of the two different hard coatings on the natural characteristics and vibration amplitude of a compressor blade. The two kinds of hard coatings are modeled by both anisotropic materials and involving their piezoelectric or piezomagnetic effects. The blade is modeled as an isotropic one. The natural frequencies and vibration amplitude of blade with different coating thickness are numerically calculated and compared. Results show that the hard coatings with different thickness play an important role in the natural characteristics and harmonic response analysis of the blade.

Abstract: In the existing Ka-band satellite channel model, the weather condition considered in the modeling are relatively ideal, so it can't be used to the dust storm weather well. In order to establish the satellite channel model under the condition of dust storm weather, the satellite channel propagation characteristic of dust storm weather is analyzed firstly. Secondly, the several states of the satellite channel model in the dust storm weather are divided by fuzzy clustering analysis method. Finally, Ka-Band satellite channel multi-state Markov model based on dust storm weather and shadow multi-path effects is established and simulated. The simulation results show that the proposed Ka-band channel model is very agreeable with the measured data.

Abstract: This paper deals with the loose detecting of tower crane bolts which is one of the core issues of the tower crane structure health monitoring. Based on the time series model ,we make research on the method of extracting the structure damage factor of tower crane. First, we establish an AR model with the detecting data, use AIC criterion to get AR model order,and then select the residual variance of AR model as the damage sensitive factor. Furthermore, we carry out a single-limb experiment on tower crane and analyze the single-limb experiment state. Good condition and injure state are compared using the above approach. It was found that the approach could effectively judge the healthy and injury states of the tower crane structure with an application value of real-time online damage diagnosis for early warning.

Abstract: Human Occupied Vehicle（HOV） is a typical system which is characterized by high nonlinearities,couplings,uncertainties and multi-stance 3D movement.It requires quite exact description and dynamic simulation research .In general,it is difficult to get precise dynamic model. this paper regards a certain HOV as research object, based on the HOV six degrees of freedom equations motion, simplified the present mathematical model of HOV space maneuvering motion , developed HOV motion simulation program by Matlab software,simulation were taken by choosing several typical motion states,the simulation results show that the HOV space motion mathematical model can reflect the HOV motion characteristics,also provide important basis for the design of HOV motion control system.

Abstract: In this paper,the models of the conductors are constructed by finite element method with a three-node, isoparametric cable element. Two numerical simulation methods that include the 4th order Runge-Kutta (referred to as R-K) method and improved time integration method on galloping are studied, and the numerical results on galloping are given by using those two methods by programming. The study result shows that dynamic responses simulated on galloping by using 4th order R-K method and improved time integration method are in good agreement in this paper, but the efficiency of improved time integration method is higher. Result of this paper can provide beneficial reference for galloping simulation calculation.

Abstract: In order to predict accurately gas concentration and design ventilation scheme in driving ventilation process under different gas emission in coal mine, based on the analysis of various ventilation factors, the prediction model structure of gas concentration for driving ventilation was designed based on RBF and BP neural network in this paper. Then MATLAB software and the observation data obtained from the coal mine sites were used to compare and analyze the prediction errors of two models, and a RBF neural network model with higher prediction precision was obtained. After that, the prediction model was used for practical application research on the gas concentration of the heading face in concrete coal mines. The research shows that the settled prediction model can not only predict the gas concentration precisely of driving ventilation, but also provide a certain theory basis for different driving ventilation equipment layout and parameters configuration in the driving ventilation process of coal mines.

Abstract: This paper proceeds from basic circuit model, analyzing the influence of different characteristic load on voltage collapse. And then make the simulation system design. Take some examples to analyze the relation of the process of voltage collapse with system and load conditions.

Abstract: The thermal performance of a new Solar air Collector with Colored Fins (SCCF) used for heating was studied. A macroscopic model was proposed based on the law of mass and energy conservation. The effects of the parameters such as dimensions of SCCF, fin angle and material of the fins on the outlet air temperature, airflow rate, effective energy and thermal efficiency were discussed. The results indicate that thermal performance of SCCF can be obviously improved by the increases of aspect ratio, fin angle and vent size. The air flow rate is the dominated factor affecting effective energy and thermal efficiency of SCCF. All these study can be used for guiding the design of SCCF.

Abstract: Powder particles in the mixer is used DEM analysis method to study and analyze the movement, it show up certain difference with different blade structure, and the paper points out that blade structure has apparent effect on the powder mixture in the mixer.

Abstract: The eigenvalue problem referring to a nonhomogeneous semi-infinite strip in plane strain is investigated here, by using the analogous methodology proposed by Papkovich and Fadle in homogeneous plane problem. Two types of nonhomogeneity are considered: (i) the modulus varies with the thickness coordinate exponentially, (ii) it varies with the length coordinate exponentially. The eigenvalues for these two cases are obtained by numerical calculation. By considering the smallest positive eigenvalue, the Saint-Venant Decay rate of the problem is estimated, which indicates material nonhomogeneity can have a significant influence on the Saint-Venant decay rate.