橡胶复合靶板抗成型装药射流侵彻研究

为研究橡胶复合靶板对成型装药射流的干扰作用机理,分析了射流侵彻“三明治”结构橡胶复合装甲时应力波在多层介质中的传播,研究了背板上射流作用区域的质点运动规律.运用开尔文—亥姆霍兹流体不稳定性原理分析了橡胶复合靶板背板质点速度对射流的干扰作用.预测了倾角以及橡胶夹层厚度对复合装甲抗射流干扰的影响.通过X-光脉冲试验和剩余穿深试验获得了射流侵彻复合靶板后射流变形情况和射流剩余侵彻能力变化情况.证明了采用应力波原理和开尔文—亥姆霍兹不稳定性分析橡胶复合靶板对射流干扰作用机理的可行性与正确性.试验证明橡胶复合装甲具有优异的防护能力,可以作为一种新型防护装甲.     

气凝胶复合材料抗弹性能的研究

使用球形弹丸对硅气凝胶、有机气凝胶和碳气凝胶复合材料进行靶试实验,研究3种气凝胶复合材料的抗弹性能.实验表明:气凝胶作为面板可以有效提高复合靶板的抗弹能力;在子弹冲击过程中,气凝胶表现出明显的应变率强化效应,吸收子弹动能的能力显著提高;当气凝胶作为夹层,铝合金为面板和背板时,面板由于没有足够的背强作用而发生弯曲破坏,导致靶板整体抗弹性能提高不明显;有机气凝胶具有较高的动态压缩强度和较大的动态失效应变,因此其抗弹性能较好;硅气凝胶的动态压缩强度虽然低于碳气凝胶的动态压缩强度,但是其动态失效应变高于碳气凝胶的动态失效应变,因此硅气凝胶与碳气凝胶的抗弹能力相当.     

YAG透明陶瓷复合靶抗弹机理研究

透明陶瓷是兼具较好的力学和光学性能的新一代透明防护材料，在低面密度、高透过率、高防护能力的透明装甲方面有重要的应用前景. 为探究YAG透明陶瓷复合靶抗弹机理，本文基于弹道枪测试平台与高速摄影技术，获得了12.7 mm穿甲燃烧弹冲击YAG透明陶瓷复合靶的弹靶冲击瞬态作用过程，确定了透明陶瓷复合靶各层损伤特征与弹体的破坏形态，测定了背板背凸量. 在此基础上，利用AUTODYN动力学有限元模拟软件，建立了YAG透明陶瓷复合靶抗制式弹过程的有限元模拟方法，探究了典型结构透明陶瓷复合靶的抗弹机理，并分析了透明陶瓷与聚碳酸酯层厚度变化对其抗弹性能的影响规律. 研究结果表明，透明陶瓷复合靶依靠透明陶瓷面板的高强度破碎弹体以有效消耗弹体冲击动能，玻璃层消耗陶瓷锥的冲击能量，背板吸收残余动能，从而实现低面密度的透明防护；透明陶瓷面板的增加能够更为有效地破坏弹体，从而实现提高装甲防护能力的目的；聚碳酸酯在一定的厚度范围区间能实现复合靶较低面密度的高效防护作用.      

破片侵彻钢/陶瓷/钢复合板的特性分析

为了从理论角度分析钢/陶瓷/钢复合板抵御爆炸破片的侵彻能力,将钢/陶瓷/钢复合靶板简化为由单层的薄板(钢面板)与陶瓷/钢复合靶板组合而成,建立了破片侵彻复合板过程的理论分析模型。结合Florence模型推导了弹体穿透钢/陶瓷/钢复合靶板的剩余速度公式。采用非线性动力学计算程序AUTODYN模拟了圆柱形破片对钢/陶瓷/钢复合靶板的侵彻过程,模拟结果与理论计算结果吻合较好,推导得到的理论公式具有一定的工程实用性。     

铝蜂窝夹芯三明治板弹道极限的实验研究

为研究铝蜂窝夹芯三明治结构的弹道防护特性,设计并实施了一系列速度在100~250 m/s之间的弹道冲击实验. 研究了在不同冲击速度、面板厚度、芯层密度和弹丸头部形状等条件下,该结构的能量吸收特性和弹道极限. 结果表明,铝蜂窝夹芯能有效提高三明治板的抗弹能力,并且对高速弹丸防护能力的提高作用更加显著. 在弹速相同的条件下,结构对平头弹丸的能量吸收低于圆头和尖头弹丸.     

落石冲击砂土-EPE-棚洞顶板的精细化动力响应模拟

落石灾害是我国三大地质灾害之一,为了更有效地进行边坡落石防护,基于LS-DYNA显式计算软件依次构建了“砂土-顶板“”砂土-EPE-顶板”三维计算模型,定性研究了各分部结构冲击应力分布规律,定量计算了顶板腹部正中单元、腹部中轴线单元的应力与位移.探究了设置EPE垫层的厚度、型号敏感性分析,揭示了落石、砂垫层、EPE垫层的能量分布特征.研究结果表明：EPE垫层具备良好的“阻滞应力传播”特性,14 m/s冲击速度下,添加0.4 m厚EPE垫层,落石峰值加速度降幅可达27.13%,速度衰减至0所需时间约由0.04 s增至0.06 s,最大冲击位移约由0.3 m增至0.4 m.顶板峰值应力由2.389 MPa降至0.893 MPa,降幅达62.62%,峰值位移由0.391 mm降至0.166 mm.缓冲效果随EPE厚度增加而逐步放缓,EPE设置厚度以0.4～0.8 m为宜,并应结合现场情况选取强度适宜的EPE型号,数值模拟与实验结果一致性较好.添加EPE垫层后,落石内能降低,动能衰减时间延长.砂垫层动能增加内能降低,EPE动能随其厚度减小而逐渐降低,内能逐步升高.     

弹体高速贯穿混凝土/钢板复合靶板的试验及理论分析

为建立弹体贯穿混凝土/钢板复合靶板的终点弹道参数分析模型.首先开展了缩比弹体高速冲击贯穿混凝土/钢板复合靶板的试验研究,测得了不同打击速度下弹体贯穿复合靶板后的弹道参数.随后,基于将后覆钢板按照弹道极限相同的原则转化为混凝土靶板的原理,通过混凝土厚靶的抗贯穿分析模型,结合已有的弹体贯穿金属靶板的公式,建立了弹体高速贯穿混凝土/钢板复合靶板的分析模型.最后,将模型预测结果与试验数据进行了对比,验证了模型的正确性.     

陶瓷靶抗侵彻特性的数值模拟研究

研究增韧对氧化铝陶瓷抗侵彻性能的影响.采用AUTODYN软件和JH-2模型参数对10%ZrO2增韧Al2O3陶瓷(简称ZTA陶瓷)和AD95陶瓷复合靶抗长杆弹侵彻性能,进行了系列数值研究,并与45号钢的抗侵彻性能进行了对比.研究结果表明,长径比一定的长杆弹对复合靶的侵彻存在一个最佳的冲击速度;在高速冲击下,两种陶瓷复合靶的防护系数均大于1,陶瓷材料能够有效提高装甲的抗长杆弹侵彻能力;不同工况下ZTA陶瓷抗长杆弹侵彻能力优于AD95陶瓷.     

冲击拉伸下环氧树脂试件中枝裂的动光弹研究

本文对冲击拉伸载荷作用下、含有不同类型预制裂纹的4组环氧树脂板试件所发生的枝裂现象,进行了动光弹研究.结果表明,枝裂与载荷大小有关、与预制裂纹的类型及尺寸无关;枝裂时的临界应力强度因子 K_(Ib)=3.08MPa,最低扩展速度 c=427m/s.     

约束应力对AD95陶瓷弹击损伤特征的影响

采用53式7.62 mm穿燃弹侵彻不同约束应力下AD95陶瓷复合靶,观察了回收靶板的弹击损伤形貌,分析了弹靶作用过程和约束应力对AD95陶瓷弹击损伤特征的影响规律.结果表明,随着约束应力的增大,陶瓷面板损伤减小,完整性提高;当约束应力达到193 MPa时弹靶之间出现界面击溃现象.约束应力条件下弹击后4 mm厚陶瓷面板上存在两种同轴锥形裂纹,所构成的两个锥形体之间是陶瓷粉碎区;约束应力提高了陶瓷动态强度,抑制了陶瓷粉碎区的生长,延长了弹靶作用中dwell的持续时间,快速消耗了弹丸动能,减小了靶板损伤.     

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