Nonlinear characteristics of induced spontaneous combustion process of sulfide ores

To investigate the relationship between nonlinear parameters and spontaneous combustion tendency of sulfide ores, nine different sulfide ore samples were taken from a pyrite mine in China, and induced spontaneous combustion experiment was carried out in the laboratory. Different stages of the induced spontaneous combustion process were studied by integrating wavelet technology and nonlinear dynamics theory. The results show that ignition points of all the ore samples are above 330 ℃, indicating that sulfide ores of the pyrite mine are difficult to combust spontaneously under normal mining conditions. Spontaneous combustion process includes three stages： incubation stage, development stage and approaching stage. The average temperature rising rate of the three stages are 1.0 ~C/min, 2.0 ~C/min and 4.2 ~C/min, respectively. During the spontaneous combustion process, mean values of approximate entropy and correlation dimension increase at first, and then decrease in the following stage. The mean value of the maximum Lyapunov exponent increases with the passage of reaction time. In a whole, correlation among the three nonlinear parameters firstly weakens, then enhances, and the best correlation period is at approaching stage. As ignition point increases, the maximum Lyapunov exponent of approaching stage decreases. Therefore, combustible tendency of sulfide ores could be qualitatively evaluated based on the maximum Lyapunov exponent of this stage.

Case Study of Wind-Induced Vibration of a Cooling Tower Under Typhoon Environment

As high-rise cooling towers are constantly emerging,wind effects on this kind of wind-sensitive structures have attracted more and more attention,especially in typhoon prone areas.Terrain Type B turbulent flow fields under the normal wind and typhoon are simulated by active wind tunnel technology,and rigid-pressure-measurement model and aero-elastic-vibration-measurement model of a large cooling tower are built.The stagnation point,peak suction point,separation point and leeward point of the throat position shell are selected to analyze pressure coefficient,probability distribution,peak factor,power spectral density and dynamic amplification factor under normal wind and typhoon.It is clarified that there exists a significant non-Gaussian characteristic under typhoon condition,which also exists in structural response level.Resonance response ratio of the total response is higher during typhoon condition.The maximum value of dynamic amplification coefficient under typhoon field is up to 1.18 times over that under normal wind.The findings of this study are expected to be of interest and practical use to professional and researchers involved in the wind-resistant designs of super-large cooling towers in typhoon prone regions.

Dynamics of Quantum Discord in Asymmetric and Local Non-Markovian Environments

The non-Markovian decoherence of quantum and classical correlations is analytically obtained when two qubits are asymmetrically subjected to the bit flip channel and phase flip channel. For one class of initial mixed states, quantum correlations quantified by quantum discord decay synchronously with classical correlations. The discovery that the decaying rates of quantum and classical correlations suddenly change at the characteristic time is physically interpreted by the distance from quantum state to the closest classical states. In a large time interval, quantum correlations are greater than classical correlations. The quantum and classical correlations can be preserved over a longer period of time via the kernel characterizing the environment memory effects.

英汉静态存在句中动词语义特征的对比研究

除原型存在动词外,英汉静态存在句对动词的限制具有一定的差异性。针对这一现象,本文对出现在该句式中的英汉存在动词的语义类型进行了比较,并在语料分析和归纳的基础上总结出了两者语义特征的异同：1）两者都具有＂非动力＂特征;2）汉语静态存在句中的动词动作性较强,多表达位移事件;英语静态存在句中的动词动作强弱不一,与位移事件的关联也没那么紧密。最后,本文从认知语义学的角度对上述差异进行解释,认为汉语静态存在句中的动词多强调＂位移的终点＂而英语静态存在句中的动词强调的则是＂事件结果＂。另外,英语静态存在句还可以运用＂假想运动＂,以假想的运动状态来指称事物的静止状态。