Sensitivity of dimethyl amino ethyl azide (DMAZ) as a non-carcinogenic and high performance fuel to some external stimuli

Hydrazine and its derivatives have been used extensively in space programs as liquid propellants. Since they are carcinogen, dimethyl amino ethyl azide (DMAZ) has been introduced as a non-carcinogenic fuel with high performance as compared to the best available fuels. DMAZ contains energetic group –N₃, which may be sensitive to some external stimuli. Thus, it is important to study various aspects of sensitivity of DMAZ in addition to its performance criteria. Various conventional tests as well as computer codes were used to investigate sensitivity of DMAZ to external stimuli such as impact, shock wave, Koenen, burning and electrostatic discharge. The results showed that DMAZ is not sensitive to impact, direct flame and shock wave. Meanwhile, it has moderate and high sensitivity to heat in confined volume and electrostatic discharge, respectively.     

煤与瓦斯突出预测研究动态及展望

笔者总结了以突出敏感性指标预测为基础的接触式煤与瓦斯突出预测技术的发展现状 ;阐述了瓦斯地质理论研究进展情况 ;对统计学方法、计算机模拟、模糊数学、灰色系统理论、神经网络技术、专家系统、分形理论、流变与突变理论等数学物理理论在煤与瓦斯突出预测领域中的应用情况作了系统的描述 ;对GIS技术、无线电波透视探测技术及以地震波为主的弹性波技术为煤与瓦斯突出预测技术的发展前景作了必要的分析。     

高压管汇磁致伸缩导波缺陷检测模拟研究

针对高压管汇导波缺陷检测问题，基于磁致伸缩效应，借助COMSOL有限元仿真软件，建立高压管汇直管段的导波缺陷检测模型，探究导波的激励条件及缺陷检测效果，分析不同参数对缺陷附近磁感应强度分布的影响。研究结果表明:在频率为10 kHz的正弦电流信号激励下，可产生沿管道轴向传播的T（0，1）模态导波，并能辨别缺陷处的回波信号。改变缺陷的尺寸参数时，缺陷附近的磁感应强度随着缺陷深度增加呈增大趋势，随轴向宽度增加呈减小趋势，不同形状的缺陷对应的磁感应强度存在一定的差异；改变激励条件，磁感应强度均随激励电流、激励频率的增加呈不断增加趋势。     

爆炸应力波在层状节理岩体中的传播规律试验研究

为了研究爆炸应力波在岩体中的传播规律,基于相似理论,开展了爆炸应力波在层状节理岩体中衰减的实验研究。研究表明,节理阻碍 应力波的传播且存在各向异性;对于垂直或小角度入射节理的应力波,在垂直方向和纵向的衰减很明显并且幅度较大,在横向衰减不明显;对 于斜入射节理的应力波,横向和垂直方向没有明显的衰减,纵向的衰减很明显并且幅度较大;应力波的合成峰值速度与炮孔密集度之间的关系 密切,当炮孔间距超过一定距离时,实际测得的速度时程为最近药包爆破产生的应力波,并非总药量产生的应力波的叠加。     

应力波在预应力锚杆内传播特性分析与工程应用

针对煤矿锚杆支护的特点,首先从理论上研究应力波在托板处、锚固开始位置、锚固结束位置的反射和透射规律;然后模拟纵波在全长锚固锚杆内传播速度与树脂-围岩粘结刚度之间的关系;最后在锚杆支护实验室进行了预应力锚杆支护实测对比试验。研究结果表明,应力波反射法不仅可以检测锚杆的锚固位置和锚固长度,而且能由锚固体波速间接检测锚杆的锚固力大小。     

超声导波技术在长输管道跨越段腐蚀检测中的应用

管道跨越段的检测一直是管道检验检测的难题之一,本文运用英国TWI集团Teletest F0CUS+MK4导波设备,对某在役的长输管道,综合选择了河流、沟壑、高速公路、水渠等多种不同服役环境管段,管後DN200至DN350不等6个跨越段进行检测,并进行案例分析。实践表明,导波检测技术对跨越段管道的单边检测距离在100右,且对管体内外壁缺陷能够全覆盖检测;导波检测的可靠性能够满足实际工程的要求。     

构造煤超声波参数影响因素的分析

一定厚度构造煤的存在是瓦斯突出发生的必要条件;同时,构造煤发育区域也往往是瓦斯富集区。因此,研究构造煤的物性参数具有重要意义。采用灰色关联度和多元回归分析相结合的方法对构造煤的超声波实验测试参数的影响因素进行半定量研究。研究结果表明:影响构造煤纵波波速和品质因子的主要因素是煤体的孔隙率、水分、灰分和挥发分。纵波波速和品质因子随着孔隙率和挥发分的增加而增加,随着水分和灰分的增加而减少,视密度和最大镜质组反射率对两者影响较小。最后,从微观角度定性分析了孔隙率、水分和灰分三个主要影响因素对构造煤超声波参数的影响机理,为超声波探测构造煤技术提供了一定的理论支持。     

激波与森林作用的实验研究

利用激波与森林的作用,有可能成为森林灭火中的一项新技术,本文报告了激波与林带作用的实验模拟方法,实验技术与装备,测试和显示手段等基本技术环节。激波在林地,林带中的传播和衰减,以及其它物理现象由纹影方法作了显示。激波诱导的压力场也作了测量。研究表明,以激波管为基础的模拟技术是成功的,实验结果对于进一步认识激波与林冠火阵面的相互作用有很好的先导意义。     

Modeling of detonation processes in chemically active bubble systems at normal and elevated initial pressures

The detonation processes in chemically active bubble liquids under elevated initial pressures are investigated theoretically. It is shown, that supersonic regimes of wave propagation can exist, if the initial pressure is relatively high and the volume fraction of the bubbles is relatively small. Characteristic values of the bubble detonation wave pressure at sub- and supersonic regimes differ by an order of magnitude.The principal possibility of detonation wave structure transformation in the case of propagation in the mixture with high initial pressure and longitudinal gradient of bubble volume fraction is predicted. The leading shock may transform into a smooth wave of compression.The Chapman-Jouguet conditions for self-sustaining supersonic bubble detonation wave is obtained.A model of shock induced single bubble dynamics and ignition taking into account the real properties of the liquid, inter-phase transition processes, mechanical mixing of phases, ignition delay and continuous shift of chemical equilibrium have been described. Calculations for the oxygen containing bubble in liquid cyclohexane have been performed.     

气体反溶剂(GAS)过程细化技术及对炸药安全性能的影响研究

介绍了气体反溶剂 (GAS)过程细化技术原理及影响细化结果的主要因素 ,并从理论和实验角度分析了炸药重结晶细化处理后 ,对撞击感度和冲击波感度的影响 ;结果表明 ,GAS过程不仅可以有效地控制炸药颗粒的粒度、粒度分布、晶形 ,而且可以有效降低炸药撞击感度和冲击波感度 ,改善炸药安全性能     

全尺寸隧道火灾实验研究与烟气逆流距离的理论预测

在建成的隧道中实施全尺寸火灾试验,得到隧道火灾自然通风模式下的烟气温度纵向变化数据和纵向蔓延情况。用OriginPro7.5软件对实验数据进行处理、拟合,得到3次实验的烟气逆流的顶棚射流温度随着离开火源距离纵向衰减规律,建立了计算烟气逆流距离的预测公式。根据隧道实体火灾实验的测量结果与理论模型的预测结果的对比,验证了理论模型的有效性,为市政公路隧道建设采用自然通风模式提供科学依据。     

厚壁管变形横波周向超声检测工艺及缺陷定位系统开发

在理论研究的基础上，利用试块对厚壁管变型横波与折射横波检测灵敏度进行了比较，证实了变型横波在厚壁管件中的检测灵敏度高于折射横波；设计开发计算软件，实现缺陷进行自动定位，大大提高现场检测效率和定位精度。     

Detonation flows in aluminium particle gas suspensions,inhomogeneous in concentrations

A physical and mathematical model of the reduced kinetics is presented describing heterogeneous detonation in suspensions non-uniform in particle concentration. The model is based on the heterogeneous media approaches, semi-empirical laws of ignition and combustion, and data on the dependence of the detonation velocity on particle concentration. Formation of suboxides and incomplete combustion of aluminum are taken into account integrally. The dependence of the heat release of chemical reactions and the fraction of unburnt particles on the initial composition is determined from the solution of the stationary problem of the structure of the detonation wave. In the calculations of unsteady detonation flows, it is supposed to solve an additional equation for the spatial distribution of initial concentrations. The problems of initiation and development of cellular detonation in flat channels in suspensions of micron-sized aluminum particles are studied. Dependences of the cell size on particle concentration in uniform suspensions are determined. The flow patterns of cellular structures, the forms of the leading front, and the propagation velocities in channels with longitudinal or transversal gradients of particle concentration are analyzed.     

Kullback-Leibler distance-based enhanced detection of incipient anomalies

Accurate and effective anomaly detection and diagnosis of modern engineering systems by monitoring processes ensure reliability and safety of a product while maintaining desired quality. In this paper, an innovative method based on Kullback-Leibler divergence for detecting incipient anomalies in highly correlated multivariate data is presented. We use a partial least square (PLS) method as a modeling framework and a symmetrized Kullback-Leibler distance (KLD) as an anomaly indicator, where it is used to quantify the dissimilarity between current PLS-based residual and reference probability distributions obtained using fault-free data. Furthermore, this paper reports the development of two monitoring charts based on the KLD. The first approach is a KLD-Shewhart chart, where the Shewhart monitoring chart with a three sigma rule is used to monitor the KLD of the response variables residuals from the PLS model. The second approach integrates the KLD statistic into the exponentially weighted moving average monitoring chart. The performance of the PLS-based KLD anomaly-detection methods is illustrated and compared to that of conventional PLS-based anomaly detection methods. Using synthetic data and simulated distillation column data, we demonstrate the greater sensitivity and effectiveness of the developed method over the conventional PLS-based methods, especially when data are highly correlated and small anomalies are of interest. Results indicate that the proposed chart is a very promising KLD-based method because KLD-based charts are, in practice, designed to detect small shifts in process parameters.     

基于风险的工业管道在线检测技术研究

化工装置工业管道面临焊接和腐蚀两大问题,装置的长期运行与管道定期检验的矛盾日益突出.通过对数字射线、脉冲涡流、超声导波三种管道在线检测技术的对比分析,结合基于风险的检验(RBI)理念,探索出一套适用于工业管道在线检验的技术,对节约企业成本、保障管道安全具有重要意义.     

Experimental study on non-destructive testing of rock bolts based on pseudo-random signal

The quality of rock bolt anchoring is closely related to the stability and safety of underground engineering and slope protection. In this paper, non-destructive testing of rock bolts is proposed based on pseudo-random signal, owing to the deficiencies of the conventional detecting method of stress wave reflection. The characteristics of pseudo-random signal for non-destructive testing of rock bolts are introduced. And the rock bolts are tested in the experiment, the time of reflection wave is identified and the length of rock bolts is calculated through cross correlation analysis between the extracted wavelet signal and the test signal. It is proved that the testing results of non-destructive testing methods based on pseudo-random signal are of low deviation. The experiment has shown that non-destructive testing of rock bolts based on pseudo-random signal is feasible with high precision.     

External pressures generated by vented gas and dust explosions

Several different data correlations have been developed for the external pressures associated with vented gas explosions and dust explosions. These correlations, which are applicable to external locations in the direct line-of-sight of the enclosure vent, are reviewed here. In addition, the application of spherically symmetric and of ellipsoidal blast wave models is explored as a possible means of calculating external pressures over a wider range of conditions than is possible with the existing data correlations. Results indicate that the spherically symmetric blast wave model can obtain a comparable accuracy (8–9 kPa standard deviation) for line-of-sight locations as the more recent data correlations. In the case of the lower blast pressures at locations perpendicular to the vent line-of-sight, the ellipsoidal blast wave provides significantly better agreement with data (to within 1 kPa standard deviation for the one set of available test data) than the spherically symmetric model.     

采场调压数学模型在煤矿火区治理中的应用

采场调压可改变采场内气体流动的状况,抑制采空区自然发火。笔者采用Ｗａｒｄ 非线性运动方程,建立采场调压数学模型,利用有限元法对其进行求解。通过对小恒山煤矿东正巷出口的调压进行计算机模拟,从而掌握火区内部参数的变化趋势,及时预测调压潜力及效果,指导调压措施的进一步实施。     

瑞利波预测煤与瓦斯突出

瑞利波勘探是近年来发展起来的一种新型的岩土原位测试勘探方法。笔者重点对瞬态瑞利波相速度的算法进行了研究。提出了对信号进行预先调制 ,随后再对所求得的相位进行修正的方法 ;另为还须考虑其仪器采集信号时的时间差影响。根据以上算法求得的相速度更接近瑞利波真速度 ,从而提高了相速度的分辨率和精确度。把瞬态瑞利波勘探法运用在矿山生产中 ,利用平面瑞利波的频散特性 ,根据瑞利波的传播速度与煤岩的物理力学性质具有相关性 ,提出了一种新型的预测煤与瓦斯突出的方法。为矿井安全生产预测预报瓦斯突出提供了一种新的手段 ,同时对突出煤层掘进前方突出危险区和安全距离的分析判断提供了一种新的方法     

钢板焊接缺陷自身高度测量

介绍了端点衍射波的产生及其计算自身高度的原理,采用常规仪器及探头测量的方法及体会。