大型浮顶式储油罐的爆炸破坏机理实验

利用可燃气体爆轰实验装置,通过乙炔/空气混合气体沿管道稳定爆轰后形成的冲击波对浮顶式储油罐模型的冲击实验,分别测得模型壁面上的超压荷载、动态应变及振动加速度时程曲线.通过对比分析,研究了大型浮顶式储油罐在爆炸冲击荷载作用下的动态响应特性及其破坏机理.在可燃气体爆炸荷载作用下,储罐结构在变形过程中诱发罐内液体产生压缩波并...     

A benchmark comparison of Monte Carlo particle transport algorithms for binary stochastic mixtures

We numerically investigate the accuracy of two Monte Carlo algorithms originally proposed by Zimmerman [1] and Zimmerman and Adams [2] for particle transport through binary stochastic mixtures. We assess the accuracy of these algorithms using a standard suite of planar geometry incident angular flux benchmark problems and a new suite of interior source benchmark problems. In addition to comparisons of the ensemble-averaged leakage values, we compare the ensemble-averaged material scalar flux distributions. Both Monte Carlo transport algorithms robustly produce physically realistic scalar flux distributions for the benchmark transport problems examined. The base Monte Carlo algorithm reproduces the standard Levermore-Pomraning model [3] and [4] results. The improved Monte Carlo algorithm generally produces significantly more accurate leakage values and also significantly more accurate material scalar flux distributions. We also present deterministic atomic mix solutions of the benchmark problems for comparison with the benchmark and the Monte Carlo solutions. Both Monte Carlo algorithms are generally significantly more accurate than the atomic mix approximation for the benchmark suites examined.     

Direct blast initiation of spherical gaseous detonations in highly argon diluted mixtures

In this study, direct initiation of spherical detonations in highly argon diluted mixtures is investigated. Direct initiation is achieved via a high voltage capacitor spark discharge and the critical energy is estimated from the analysis of the current output. Stoichiometric acetylene–oxygen mixtures highly diluted with 70% argon is used in the experiment. Previous investigations have suggested that detonations in mixtures that are highly diluted with argon have been shown to be “stable” in that the reaction zone is at least piecewise laminar described by the ZND model and cellular instabilities play a minor role on the detonation propagation. For the acetylene–oxygen mixture that is highly diluted with argon, the experimental results show that the critical energy where the detonation is “stable” is in good agreement with the Zel’dovich criterion of the cubic dependence on the ZND reaction length, which can be readily determined using the chemical kinetic data of the reaction. The experimental results are also compared with those estimated using Lee’s surface energy model where empirical data on detonation cell sizes are required. Good agreement is found between the experimental measurement and theoretical model prediction, where the breakdown of the 13λ relationship for critical tube diameter – and hence a different propagation and initiation mechanism – is elucidated in highly argon diluted mixtures and this appears to indicate that cellular instabilities do not have a prominent effect on the initiation process of a stable detonation.     

氦氢混合气体中受激拉曼散射的脉宽特性

 308nm准分子激光泵浦的氢拉曼散射介质中渗入一定比分的氦气，其输出的一阶斯托克斯光S1的脉宽将发生变化。实验获得不同氦比分的S1脉宽在20-45ns之间，与渗入氦的浓度有关。从氦对氢拉曼增益系数的影响，对实验结果进行了理论分析。     

Study on volumetric measurement and correlations for MTBE+1-propanol+decane at 298.15 K and atmospheric pressure

Summary Experimental densities for the ternary mixture x₁MTBE+x₂1-propanol+(1-x₁-x₂)decane and the binary mixtures xMTBE +(1-x)1-propanol and x1-propanol+(1-x)decane have been measured at 298.15 K and atmospheric pressure, using a DMA 4500 Anton Paar densimeter. Excess molar volumes were determined from the densities of the pure liquids and mixtures. Attending to the symmetry of the studied mixtures, suitable fitting equations have been used in order to correlate adequately the experimental data. For the ternary mixture, experimental data were also used to test several empirical expressions for estimating ternary properties from experimental binary results.     

Critical radius of explosive gaseous mixtures with initial concentration gradients

A synthetic review of works concerning detonation of non-uniform explosive mixtures allows to retain a criterion of detonation onset. This criterion is due to Zel'dovich and then Makhviladze. The present study proposes to adapt Makhviladze's criterion to define the formation point of a quasi-stationary detonation in spatially non-uniform, non-stationary and non-preheated gaseous mixtures. The temperature increase of gaseous mixture is due to the travelling shock. This point is compared to the critical radius defining the distance for which the Chapman-Jouguet conditions are attained. The detonability of a non-uniform medium (propane/oxygen mixtures) is characterized by a small scale experimental investigation and by application of a simple advection-diffusion model. Accepted 3 March 1996     

Thermomechanics of Porous Media - I: Thermohydraulic Model for Compacted Bentonite

A general thermomechanical model is derived for a mixture. The model describes the behavior of the mixture via proper choices of free energy and dissipation function. A model for any combination of the mixture constituents can be reduced from the general model. The theory is applied to a thermohydraulic model for a mixture of compacted bentonite, liquid water, vapor, and air with the assumption of rigid skeleton and constant uniform porosity. The free energy of the system is chosen to take into account the individual nondissipative behaviors of the constituents and their mutual interactions, namely, adsorption and mixing of the gaseous constituents. The choices for the interaction terms are based on the equilibrium conditions for the water species in different combinations of the constituents. The resulting thermodynamically consistent macroscopic model is fitted to a suction experiment and applied to a simple one-dimensional thermohydraulic simulation of the bentonite buffer of the Febex in situ test. The results calculated with finite element method are successfully compared to measurements.     

一个使用氦基混合气的小单元漂移室的实验研究

利用宇宙线分别研究了一个小单元漂移室在He/C3H8(60/40)和He/CH4(60/40)两种氦基混合气下的性能.作为比较还测试了在Ar/CO2/CH4(89/10/1)混合气下的性能.研究表明上述氦基混合气的空间分辨和dE/dx分辨好于Ar/CO2/CH4(89/10/1)混合气.使用He/C8H8(60/40)可以获得110μm的空间分辨,在30—40次取样下dE/dx分辨可以达到6%—7%.     

离子通道的混合密度参数估计与状态判别

本文针对多电导水平离子通道的由多个正态分布加权组成的混合分布特点,用EM迭代算法对混合分布中的参数进行极大似然估计,并在此基础上,利用混合分布中最可能的成分判断通道状态,从而还原通道潜在信号,克服了离子通道分析软件PCLAMP中参数估计与状态还原的缺陷。