沙墙吸能作用对爆炸冲击波影响的数值分析

由沙袋堆积起来的沙墙对强冲击波具有很好的消波吸能作用,在爆炸实验中对结构有一定的防护作用.沙墙在爆炸冲击波作用下,飞散形成颗粒相,吸收冲击波的能量,降低冲击波对结构的冲击作用.分别使用通用非线性动力学数值计算程序LS-DYNA和自编的多相流程序,计算了某封闭空间中沙墙对爆炸冲击波消波吸能的作用.自编的多相流程序可以计算沙子的飞散,可以考虑对流、辐射传热的吸能作用.LS-DYNA没有这些功能,但是却可以模拟复杂的爆炸与结构相互作用的问题.两种程序对比计算的结果可为使用商业软件LS-DYNA进行类似的复杂数值计算提供参考和修正.     

密闭空间爆后准静态气压及地运动分析

准静态气压参数和地运动速度参数是保证密闭空间爆炸作业安全开展的重要参考.通过获取某工程现场3次爆破后的实测地运动速度数据和准静态压力数据进行时频域分析,结果表明,不同比例药量下,质点振速时程曲线和频域曲线均具有一致性,随着爆心距增加,质点振速幅值减小,主要频段趋近低频段,比例药量仅对地运动速度幅值有影响,对频域分布及主频影响不大.不同质量沙墙对准静态气压峰值及衰减速度均有影响,沙墙质量越小,爆后准静态气压峰值越大,其衰减越快.     

爆炸荷载多尺度分析方法在仿真计算中的应用

基于爆源子结构的爆炸荷载多尺度分析方法为复杂工况和大范围场地的爆炸数值计算提供了高效解决途径.该方法虽然理论清晰，计算效率高，但涉及大量空间节点数据的比对和读写，直接在仿真计算中应用可能会存在操作困难等问题.本文简要介绍了该方法的基本理论，研究了该方法在仿真计算中的应用技术，对单爆源和多爆源2种算例进行了对比分析.研究结果表明，爆炸荷载多尺度分析方法可较好地应用于大当量爆炸荷载作用下的大范围工程场地动力响应计算，计算效率显著优于炸药-介质-目标整体计算模型.计算得到的标准化爆炸荷载可快速加载至介质任意位置，避免重复建模和流固耦合计算，大幅提高计算效率.基于Python的自编程序可快速准确比对和读写空间节点坐标和数据信息，极大提高前处理效率.     

深埋岩石洞室受爆炸应力波作用的破坏效应

基于工程观测资料,采用现场试验数据综合分析、小比例化爆模拟实验和岩石脆性破坏模型的三维动力有限元数值模拟的方法,研究了深埋岩石洞室在爆炸应力波荷载作用下随着各种条件的变化而发生的破坏效应。     

ZrO2泡沫陶瓷对瓦斯爆炸的影响

为有效阻隔煤矿井下一次瓦斯爆炸后伴随的连续爆炸或多次爆炸,在爆炸实验管道内设置ZrO2泡沫陶瓷阻隔爆装置,进行瓦斯爆炸实验,分析ZrO2泡沫陶瓷的厚度和孔隙度对瓦斯爆炸压力波波速及超压的影响。结果表明：设置陶瓷阻隔爆装置后的爆炸压力波上升速率和超压较空管时均有所下降;30 mm厚的陶瓷对前驱压力波上升速率的衰减作用明显;泡沫陶瓷能够抑制爆炸波能量的传播,降低爆炸强度。该结果为煤矿阻隔爆技术的研究提供了新思路。     

隔爆墙后爆炸冲击波绕射与超压分布规律

基于爆炸实验与数值模拟,对爆炸载荷作用下隔爆墙后的冲击波绕射和超压分布规律进行了研究.首先,开展了隔爆墙对爆炸冲击波隔离效应的实验,得到了有/无隔爆墙条件下相同爆距处的冲击波超压时程曲线.在此基础上,采用流体动力学软件AUTODYN对爆炸冲击波的绕射过程进行了数值仿真,通过与实验结果的对比验证了模型的有效性.结合数值模拟和量纲分析,得到了不同爆炸当量、爆距、墙高等参数下隔爆墙后不同区域的冲击波超压分布规律,并给出了隔爆墙后近地面超压峰值的工程计算公式,为隔爆墙的设计和安全评估提供了依据.      

岩石洞室受爆炸应力波作用的破坏效应

基于工程观测资料,采用现场试验数据综合分析、小比例化爆模拟实验和岩石脆性破坏模型的三维动力有限元数值模拟的方法,研究了深埋岩石洞室在爆炸应力波荷载作用下随着各种条件的变化而发生的破坏效应.总结了洞室宏观破坏的一般规律,编制出新的洞室破坏分区表.水泥砂浆材料小比例化爆模拟实验表现了完整多孔硬岩中洞室应力波破坏的特征,扫描电镜试验表明洞室微观损伤破坏的变化规律与宏观破坏现象具有一致性.在数值模拟研究中采用了实测经验应力波规律和能表现材料破坏后性能劣化及脆性破坏非连续各向异性发展的材料模型,创建了适用的洞室工程破坏准则,编制了动力有限元参数化分析的计算程序,计算了大量模型的洞室破坏历程和最终工程状态,工程实例计算表明数值模拟方法是合理可行的.通过数值模拟研究了在不同荷载、工程特征、地质特征下岩石洞室破坏的定性和定量特征.     

爆炸焊接用半球结构体的降压实验

如何减小爆炸焊接噪声影响的问题成为目前迫切需要解决的问题.为解决冲击波和噪声扰民问题,因为药量不能做到微差起爆降低声源,这里着重从传播途径上考虑,提出了在爆破场地建设一种专用的半球阻波结构.依据内爆、裸爆超压测试,比较了裸爆、内爆超压降低趋势.在半球阻波体开口方向,消压效果可达50%,在开口侧向90°方向,消压效果可达90%.     

玻璃窗泄爆下室内燃气爆炸荷载规律试验研究

建立了一套野外试验系统,设计了19组试验工况,分别研究了室内燃气浓度、泄爆窗玻璃破坏强度及面积对室内燃气爆炸荷载的影响,得到了玻璃窗泄爆条件下室内燃气爆炸的荷载特性和变化规律。试验研究结果表明：甲烷浓度在7.5%~10.5%时,室内燃气爆炸产生两个压力峰值,并引起声振不稳定燃烧,形成远大于第一个压力峰值的第二压力峰值;甲烷浓度较高时,声振现象不容易出现,只产生一个压力峰值,其大小仅与泄爆口封闭物有关;当甲烷气体浓度为9.5%时,燃气爆炸反应最剧烈,第一个压力峰值和声振压力峰值均为最大;提高泄爆窗玻璃破坏强度,会导致爆炸荷载的第一个压力峰值增大;增加泄爆窗面积,会使第一个压力峰值略微降低,但第二个的声振压力峰值则会大幅降低。研究结果有利于了解玻璃窗泄爆条件下室内燃气爆炸荷载规律和作用机理,并对进一步研究燃气爆炸荷载下结构的动力响应和破坏形态具有实际意义。     

地下箱形结构在爆炸冲击荷载作用下的动力反应分析

在一定距离的常规武器爆炸作用下,地下防护结构可能不会发生由于抗力不足而产生破坏,但是爆炸冲击荷载会引起结构内部很大的震动加速度环境,造成结构内部人员伤亡和设备破坏.综合考虑引起结构振动的各种影响因素,采用爆腔-岩土介质-结构系统动力相互作用模型,运用LS-DYNA动力分析软件,对典型的地下箱型结构在顶爆、侧爆和侧顶爆3种不同爆炸工况进行了数值模拟计算.初步分析了箱型结构在不同当量和不同爆炸点的常规武器爆炸荷载作用下的动力反应规律和特点,可为箱型结构在爆炸荷载下的隔震设计提供参考.计算结果表明:在常规武器爆炸作用下有必要对重要的箱型地下人防指挥工程进行隔震设计;可以采用爆腔-岩土介质-结构系统动力相互作用有限元模型进行爆炸动力反应分析.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the