Advanced Materials Research Vol. 629

Abstract: The spur gear pair’s nonlinear equation of motion including piece-wise backlash and internal error excitation is derived in this research. The worn tooth effect in time-varying mesh stiffness is introduced to do in-depth investigation of the dynamic traits for gear transmission system with wear fault. The internal excitation frequency is selected as a criterion to calculate the bifurcation diagram and the corresponding Lyapunov exponents. Some auxiliary analyzing meanings such as Poincaré maps, phase trajectory, power spectrum and time history curve are utilized to illustrate the system’s nonlinear behaviors with special parameter settings. Different routes to chaos and abundant nonlinear phenomena have been observed in this nonlinear gear transmission system.

Abstract: As the most important error source in the heterodyne interferometer, the nonlinearity errors reduce the measurement accuracy in the nanometric or picometric measurement. This survey states both the definition of nonlinearity errors and the cause of the errors. Moreover, two kinds of methods for detection and compensation of the nonlinearity errors are also discussed respectively in this paper.

Abstract: Based on computer texture analysis methods, the relationships between laser speckle texture features of grinding surfaces and surface roughness are investigated. The laser speckle texture pictures of different surface roughness are acquired by a simple equipment which consists of a digital camera and a diode laser. The texture method based on Gibbs Random Fields model is used to analyze laser speckle patterns. Gibbs texture features with the second-order neighborhood are extracted. The experiment results display that the surface roughness information included in the laser speckle texture pictures is monotonous withβ2~β5 Gibbs texture features. For comparing, normalized texture features has been done. This method can extract object’s surface roughness information which is the same material and machined by the same method through calibrating beforehand.

Abstract: High-frequency surface acoustic waves (SAW) were generated and transmitted along single-crystal lithium niobate (LiNbO3). The standing surface waves (SSAW) formed between two parallel inter-digital transducers (IDTs) on a LiNbO3 substrate, were employed to drive the micro-drop mixer. An SSAW device was designed, micro-machined and tested. When an AC signal with the frequency of 61.4MHz was applied to the IDTs, vortex appeared in the drop consisted of two incompatible liquid (ink and glycerol). The evolution of the vortex was recorded in this work. With the evolution of the vortex, mixing process of two incompatible liquid has been demonstrated. The mixer is of significant relevance for many bio-technological applications and in particular for lab-on-chip. While the experimental liquids were mutually incompatible, the ink could only be divided into smaller drops.

Abstract: A high-temperature, high-pressure evaporation model for HAN-based liquid propellant droplet was built, which considered the multicomponent droplet, the unsteady heating-up, the droplet surface regression, and the nonideal gas effect. Based on the state equation of the real gas, a computation method applicable to high-pressure thermophysical property parameters was established. By use of the evaporation model, the evaporation process of a LP1845 droplet in the nitrogen atmosphere for pressures of 100–300 atm and temperatures of 1600 K was studied. The results indicate that the droplet radius increases firstly and reduces afterward as the evaporation goes on, and the reduction rate of the radius satisfies the D2 law. The droplet temperature rises rapidly at the beginning, then maintains stable gradually at an equilibrium value. When the ambient temperature remains constant, with increasing ambient pressure, the time to reach the equilibrium temperature lengthens, but the droplet lifetime shortens.

Abstract: Applied damping material (ADM) is today widely used to reduce vibrations and sound radiations by damping out the resonant peaks of structures. The efficient use of ADM becomes more and more important from an optimization design view. In this paper, the potential of using topology optimization as a design tool to optimize the distribution of ADM on a vibrating plate to minimize its sound radiation is investigated. A solid isotropic material with penalization model is described based on a special interface finite element modeling for viscoelastic layer. Numerical analysis has been applied to demonstrate the validation of the proposed approach and shows that significant reductions of the sound radiation powers over a broadband frequency range are achieved by the optimized results.

Abstract: This paper presents the experimental study of an improved PV solar module based on an outdoor point-focus two-axis tracking reflective concentration photovoltaic system in Nanjing. The special improved silicon solar cell was utilized to fabricate the module. Relationship between the concentration ratio and maximum power of the module was illustrated. The results showed that the electricity output was improved by enlarging the illumination on the solar cell through increasing the number of flat-glass mirrors. The optimum performance of concentration photovoltaic system was obtained with 18 mirrors. Nonideal module design and cooling approach may result in the deterioration of silicon module efficiency for higher concentration ratio application.

Abstract: A kind of shared multi-channel on-chip memory CMP architecture is proposed in this article to efficiently support embedded applications. For the multi-channel on-chip memory being scarce resource, optimal space management mechanism of multi-channel on-chip memory is proposed including automatic space allocation strategy based on application parallelization mapping pattern and optimal space utilization scheme. ILP-model-based analysis of system performance verifies that the proposed optimal space management mechanism can deeply exploit the efficiency of multi-channel on-chip memory to improve system performance.

Abstract: Railway wheel acoustic radiation takes a large proportion of the wheel-rail noise . This paper mainly focuses the ways to reduce railway wheel acoustic radiation to control wheel-rail acoustic radiation, and ultimately to reduce the railway environmental noise. In this paper, Optimization mathematical model of wheel acoustic radiation is built according to the wheel vibration and acoustic radiation theory, and obtaining the section optimization and acoustic radiation power of wheel by drawing up the genetic algorithm (GA) program and analyzing the acoustic radiation of the wheel according to Finite element and boundary element model. The result shows that the optimized acoustic power is reduced to some extent, even by 2dB at the peak point within 5000Hz. Since high-speed railways are put into operation in China, it has been more convenient for people to go out. However, serious railway environmental noise occurs by the way. The noise produced when the train is running affects not only passengers and working staff on the train, but also environment and residents around the railway. For this reason, to reduce the noise with proper measures is good for environment protection, sustained and healthy development of rail transportation as well. According to wheel-rail noise theory, the main approaches to reduce noise as follows:(1) Adopt damped wheel. (2) Add rubber isolation layer between tread and web of the wheel to form resilient wheel. (3) Optimize the wheel shape. (4) Reduce acoustic radiation efficiency of the wheel. This paper discusses how to reduce acoustic radiation of the wheel and railway environmental noise according to optimize the wheel shape by mainly analyzing the wheel of high frequency radiation noise.

Abstract: Particle trajectory within rotating cylinders has been investigated in terms of radial positions by using the discrete element method (DEM). The dynamic information of particle groups has been obtained under a wide range of rotation speed by a method of particle marking and tracking. The results show a periodic way of inwards trend for particle motion within material bed. The period of particle motion is directly related to the rotation speed of the cylinder. However, the residence time of particles in the active layer shortens with periods, while that in the static zone prolongs. Moreover, the peak value of radial positions periodically decays, whereas the valley value periodically increases. This research laid a good foundation for further research on particle mixing and heat transport within the material bed in rotating cylinders.