Applied Mechanics and Materials Vol. 142

Abstract: A very short impulse energy called ‘impulsion energy’ can be produced when the gear meshing with gear pitting fault and excited the resonance of the structure. The common techniques have inconvenience to deal with this vibration signal. A new fault diagnosis method based on EEMD and instantaneous energy density spectrum is proposed here. The IMFs generated by EEMD can alleviate the problem of mode mixing and approach the reality IMFs. The characteristic frequencies were found in the instantaneous energy density of Hilbert spectrum. The effectiveness of this method was demonstrated by analysis the vibration signals of a gear with pitting fault.

Abstract: For description of rotor-bearing system, a symmetrical flexible rotor supported by two turbulent journal bearings is modeled. The analysis of the rotor-bearing system is implemented under the assumptions of turbulent lubricant flow and a long bearing approximation. The bifurcation and chaos behaviors of the system are investigated for various rotational speeds. The motion equations are solved by the self-adaptive Runge-Kutta method. The numerical results show that the bifurcation of nonlinear responses of the system varies with the rotational speed of the rotor. It is found that the rich and complex dynamic behaviors of the system include period-1, period-doubling, quasi-periodic and chaotic motions etc.

Abstract: The paper puts forward the dynamic path planning algorithm based on improving chaos genetic algorithm by using genetic algorithms and chaos search algorithm. In the practice of navigation, the algorithm can compute at the best path to meet the needs of the navigation in such a short period of planning time. Furthermore,this algorithm can replan a optimum path of the rest paths after the traffic condition in the sudden.

Abstract: This paper investigates single machine materials manufacturing process with periodic maintenance, which has been proved as a NP-hard problem. Such that, combining the advantages of the classic List Scheduling (LS) algorithm, the Longest Processing Time first (LPT) algorithm and the genetic algorithm, two hybrid genetic algorithm (LS-GENETIC algorithm and LPT-GENETIC algorithm) were proposed to solve the problem. Computational results have shown that both LS-GENETIC algorithm and LPT-GENETIC algorithm perform satisfactorily.

Abstract: According to the equation of shrunk interface pressure and the condition of diametrical ratio based on the theory of equal strength, it is found that the diametrical ratio isn’t true of the condition of diametrical ratio and the distribution of stress isn’t very equality through analyzing and calculating the diametrical ratio and stress to a super high pressure cylinder. Then aim at the problems existed in the super high pressure cylinder, it is taken the improved design. The super high pressure cylinder has much better than original one in distributing of stress. It is shown that the improved design project has a better technical result.

Abstract: Through the analysis of stress in ultra high-pressure cylinders, found that its stress distribution is very uneven. In order to use the principle of autofrettage for improving design of the cylinders, first with Faupel-Furbe formula to calculate estimates of diameter ratio, and thus are inner and outer diameter of the cylinder block. Then the cylinder is determined parameter of autofrettage on the cylinder such as the optimum radius of elastic-plastic junction and the optimum autofrettage pressure. Finally, analysis and calculation of stress in improved design cylinder, the results show that the improved design of cylinder have a greater degree of improvement in weight, size and stress distribution of three areas. Key words: autofrettage; ultra-high pressure cylinders; diameter ratio; stress distribution.

Abstract: Recent years, considering the decreasing amount of nature resource on Earth, It’s very important to expand the field of scientific research, and to develop new resources. Based on 400 rail CE-1 laser altimeter altimetry data (2B data), to process the data, delete the singular of data, and import the remaining data into ERDAS IMAGINE9.1 generating lunar planet DEM. Its spatial resolution is more accurate than the existing model of the lunar DEM.

Abstract: The effect of different ammonium and nitrate ratios (NH₄⁺-N : NO₃^--N = 0:100, 25:75, 50:50 and 75:25) on growth and yield of Chinese kale (Brassica alboglabra Bailey) with 3 cultivars were studied in hydroponics. The results indicated that, compared with the complete nitrate treatment, plant height, stem diameter and biomass of Chinese kale were increased in the low enhancement of ammonium (25%) in nutrient solution, while plant growth and biomass were decreased in the medium (50%) and high (75%) enhancement of ammonium. Ammonium enhancement treatments increased the root/shoot ratio of Chinese kale. Low enhancement of ammonium (25%) in nutrient solution had no significant effect on root activity of Chinese kale, while it was decreased by the medium (50%) and high (75%) enhancement of ammonium treatments. Nutrient solution with 25% ammonium enhancement maintained a high root absorption capacity and increased plant biomass, so it was appropriate to hydroponics for Chinese kale.

Abstract: Effect of nitrogen level (50, 100, 200, 300, 400 mg/L) on pigment accumulation of flower stalk in Chinese kale (Brassica alboglabra Bailley) (cv. Zhonghua) were studied by hydroponics. The results showed that chlorophyll concentration of flower stalk in 50 mg/L and 100 mg/L N treatments were higher before stage Ⅲ, those in 50 mg/L were the highest, while those in 200 mg/L N treatment were the highest at stage Ⅳ and Ⅴ. Carotenoid concentrations in 50mg/L N treatment were the highest during flower stalk development (except at stageⅤ), while those in 100mg/L N treatment were the highest at stagesⅤ.The concentrations of flavonoids and anthocyanin in flower stalk epidermis were the highest in 100 mg/L N treatment, those in 50mg/L N treatment were higher than other treatments. The ratio of anthocyanin/chlorophyll in flower stalk epidermis also were the highest in 100 mg/L N treatment, and higher in 50mg/L N treatment, thus the epidermis appeared mauve in 50 and 100mg/L N treatments.