混凝土板爆破作用数值分析

混凝土板是爆破拆除经常遇到的爆破对象,是建筑物的基本构件．爆炸应力波峰值随距离衰减是工程爆破参数设计的理论依据之一．通过数值计算,研究爆炸应力波峰值随距离的衰减规律．研究结果表明,与无限混凝土介质相比,爆炸应力波峰值在混凝土板中衰减较快．应力波峰值的衰减指数随装药量增大而减小,衰减指数的变化率也随装药量的增大而减小．     

一种岩石概率型本构及其应用

在岩石材料非均匀特性的基础上,建立了弹塑性概率材料本构．认为材料单元的切线模量与破坏强度都是服从二参数Weibull分布的随机量,通过用户材料子程序将该本构导入到LS—DYNA3D中,推导了程序流程,分析了导入过程中的关键技术．算例验证表明,应用该本构模拟得出的现象与实验观测完全一致,这是确定性本构无法实现的．     

60Co γ‐Irradiation‐Initiated “Living” Free‐Radical Polymerization in the Presence of Dibenzyl Trithiocarbonate

The free‐radical polymerization of vinyl monomers in the presence of dibenzyl trithiocarbonate (DBTTC) and under ⁶⁰Co γ‐irradiation is of living character. Under ⁶⁰Co irradiation, the bonds between benzyl group and sulfur were cleaved, benzyl radicals initiate the polymerization. The propagating radical together with trithiocarbonate radicals form a dormant polymer chain. The fast equilibrium between propagation radical and dormant polymer chain controls the polymerization.     

Structural Stability,Tunable Electronic,and Optical Properties of XSi2N4/Cs2SnI6 (X = Cr,Mo, W) Heterostructures: First-Principles Studies

Novel optoelectronic and photovoltaic devices are promising, exploiting MoSi₂N₄-based van der Waals (vdW) heterostructures. Herein, six vertical XSi₂N₄/Cs₂SnI₆ (X = Cr, Mo, W) heterostructures are constructed and the atomic structure, stability, and optoelectronic properties via first-principles calculations are investigated. The results of binding energies indicate that XSi₂N₄/SnI₄ is energetically favorable to be established compared to the XSi₂N₄/CsI. Computed charge density differences show that at the XSi₂N₄/SnI₄ interface, there is no significant charge migration or rearrangement, making it unsuitable for use in charge transport devices. It is worth noticing that the built-in electric field induced by electron transfer from CsI to the XSi₂N₄ layer prevents light-induced electron and hole recombination, thereby improving carrier lifetime. Furthermore, the CrSi₂N₄/CsI heterostructure exhibits a wider range of visible light absorption, demonstrating its potential for applications in photoelectronic devices. The electronic and optical properties of XSi₂N₄/Cs₂SnI₆ can be tuned through element substitution. The findings could provide useful guidance for designing XSi₂N₄/Cs₂SnI₆ photoelectronic and photovoltaic devices.     

Medium effect on dielectric relaxation behaviors of 4A zeolite bulk dispersion system

Dielectric spectra of 4A zeolite particles bulked in deionized water (4A/W) or cyclohexane (4A/C) were measured respectively under different temperatures, and two dielectric relaxations were found in both of 4A/W and 4A/C. Because of existence of water molecules in pores, both low and high frequency relaxation times (τ_LFR and τ_HFR) of 4A/Wdecreasedmore sharply than 4A/C with increasing temperature. According to the temperature dependence of τ_LFR and τ_HFR, the activation energies of Na⁺ interacting with framework under hydrated and dehydrated environments were calculated respectively, and the original properties of Na⁺ in dehydrated zeolite were obtained by analyzing the dielectric properties of 4A/C. Furthermore, a transient state of Na⁺ motion with temperature was found in 4A/C system.     

X-ray microscopy of novel thermoplastic/liquid crystalline polymer blends by mechanical alloying

Incorporation of liquid crystalline polymers (LCPs) into commodity polymers remains a challenge in the design of high-performance, low-cost polymeric blends. Blends of a thermoplastic polymer and a nematic LCP are produced here by mechanical alloying. Functionality sensitive X-ray microscopy reveals LCP dispersions as small as 100 nm in diameter. Intimate mixing remains upon subsequent melt processing, indicating that mechanical alloying is suited for applications such as recycling.     

苯并䓛盘状液晶:合成、柱状相和光物理性质

盘状液晶分子由稠环芳核和围绕的多条柔性链构成, 具有独特的自组装有序超分子结构、半导体性质和光学性质. 其可通过溶液或喷墨打印技术加工成为光电子薄膜器件, 具有低成本优势. 通过Suzuki-Miyaura交叉偶联和Scholl氧化环化策略, 合成了一系列新的具有苯并䓛结构的非对称酸酐、羧酸酯、酰亚胺和苯并咪唑稠环衍生物, 并对其液晶性和光物理性质进行了详细研究. 通过偏振光学显微镜(POM), 差示扫描量热法(DSC)和小角度X射线散射(SAXS)测试表明, 这些极性盘状化合物自组装堆积呈六方柱状(Col_hex)液晶相, 其中, 最宽的液晶温度范围达206 ℃. 官能团和共轭体系大小决定了相变温度和液晶范围. 荧光测试结果表明, 化合物溶液中绝对量子产率高达34%, 根据官能团不同, 这些化合物发蓝、绿和红光. 借助密度泛函理论(DFT)计算, 解释了该系列极性盘状液晶分子发光性质的差异. 基于本工作的合成方法, 从萘酸酐原料出发为构建结构多变、性质丰富的π-共轭(杂环)芳烃盘状液晶化合物提供了新途径.     

聚氨酯结构与径向分布的分子动力学模拟

采用分子动力学方法计算得到DHI-乙烯醇聚合体系统的结构和径向分布函数.讨论了系统结构和径向分布函数与温度和压力之间的关系.结果表明粘合系统的空间分布一般地随着温度和压力的增加而收窄,对增加聚氨酯系统的粘合性具有积极的意义.