Properties of acoustic resonance in double-actuator ultra-sonic gas nozzle: numerical study

The ultra-sonic gas atomization(USGA) nozzle is an important apparatus in the metal liquid air-blast atomization process.It can generate oscillating supersonic gas efflux,which is proved to be effective to enforce the atomization and produce narrow-band particle distributions.A double-actuator ultra-sonic gas nozzle is proposed in the present paper by joining up two active signals at the ends of the resonance tubes.Numerical simulations are adopted to study the effects of the flow development on the acoustic resonant properties inside the Hartmann resonance cavity with/without actuators.Comparisons show that the strength and the onset process of oscillation are enhanced remarkably with the actuators.The multiple oscillating amplitude peaks are found on the response curves,and two kinds of typical behaviors,i.e.,the Hartmann mode and the global mode,are discussed for the corresponding frequencies.The results for two driving actuators are also investigated.When the amplitudes,the frequencies,or the phase difference of the input signals of the actuators are changed,the oscillating amplitudes of gas efflux can be altered effectively.     

随机调幅Rattling系统建模

本文研究了一个随机调幅Ｒａｔｌｉｎｇ系统·代替常用的数值分析方法,采用非高斯截断技术,导出一个由三维平均映射描述的离散的随机模型·实测指出该模型能揭示浑沌随机性质,故更适于用以模拟齿轮箱噪声源     

Modeling of stochastic modulated rattling system

Rattling vibration is an important noise source of gear-box. To control that noise, it is necessary to elaborate a mathematics-mechanical model on rattling gears. In this paper, a rattling system modulated by noise was investigated. Instead of performing the very tedious numerical calculation, a discrete stochastic model described by three dimensional mean mapping was established by means of the Non-Gaussian closure technique. Through the example, the chaotic stochastic behavior may be revealed. In comparison with deterministic model, the model developed in this paper is more approximate to practice and more available for acoustic investigation, so that it is suggested to be applied to modeling on rattling vibration.     

掺镧方钴矿型晶体的拉曼光谱测定

本文用熔融退火法生长了热电材料掺镧方钴矿 (LaxFe3CoSb12 )晶体。用背散射方法测定了不同掺镧量晶体的拉曼光谱。我们认为稀土镧原子占据了方钴矿结构中的空位 ,这些填充空位的离子参与结构中的晶格振动 ,使拉曼谱线位移并加宽。随着含镧量的增加 ,镧原子振颤自由度降低 ,谱线的加宽程度减小。     

Spatially discrete reaction–diffusion equations with discontinuous hysteresis

We address the question: Why may reaction–diffusion equations with hysteretic nonlinearities become ill-posed and how to amend this? To do so, we discretize the spatial variable and obtain a lattice dynamical system with a hysteretic nonlinearity. We analyze a new mechanism that leads to appearance of a spatio-temporal pattern called rattling: the solution exhibits a propagation phenomenon different from the classical traveling wave, while the hysteretic nonlinearity, loosely speaking, takes a different value at every second spatial point, independently of the grid size. Such a dynamics indicates how one should redefine hysteresis to make the continuous problem well-posed and how the solution will then behave. In the present paper, we develop main tools for the analysis of the spatially discrete model and apply them to a prototype case. In particular, we prove that the propagation velocity is of order $a{t}^{?1/2}$ as $t\to \infty$ and explicitly find the rate a.     

Sound quality evaluation of vehicle suspension shock absorber rattling noise based on the Wigner–Ville distribution

In this paper, a new sound metric–Sound Metric based on the Wigner–Ville distribution (SMWVD) – was developed to investigate the relationship between subjective evaluations and vehicle suspension shock absorber rattling noise, which substantially affects passengers’ psychological and physiological perceptions. A complete vehicle road test was conducted to measure the interior shock absorber noises, which were subjectively evaluated by 20 jurors. Conventional psychoacoustic indices, i.e. loudness, sharpness, roughness and fluctuation strength, were used to calculate the correlation coefficients between the objective and subjective evaluations, and then, the results were compared with the performance of the SMWVD. The results show that conventional sound metrics have poor relationships with the subjective ratings, while the SMWVD displayed a high correlation of >0.9 between the objective evaluation and the subjective evaluation. These results indicate that the SMWVD can be used to estimate the rattling noise index of a suspension shock absorber without jury evaluation.