综放巷内充填原位沿空留巷技术

针对综放沿空留巷的技术难点,在分析综放沿空留巷围岩结构力学模型的基础上,提出了巷内充填原位沿空留巷的新技术。此项技术有两个关键方面:一是大断面全煤巷道顶煤完整性的维护;二是大体积长距离充填体的整体稳定性控制。对巷内基本支护为梯形金属支架的原有巷道,提出了实施此项新技术的具体方案。现场工业性试验表明,该项技术的应用是成功而有效的,可在类似条件的综放工作面推广应用。     

三面受火钢筋混凝土轴心受压柱的受力性能试验研究

本文通过12根三面受火的钢筋混凝土轴心受压柱在不同温度（20～950℃）下的试验，分析了其强度和变形规律。结果表明，不均匀受火的钢筋混凝土轴心受压柱的破坏形态和特征与常温下的截然不同，都是小偏心受压破坏，而且其受力性能与预加荷载水平、温度值和荷载温度途径等密切相关。     

半刚性节点研究综述及展望

随着钢框架体系的广泛应用,其理论设计体系的研究更显突出,其中梁柱连接节点的半刚性连接是最重要的部分。《钢结构设计规范》(GB50017-2003)中对半刚性连接提出了条文要求,但没有必要的理论支持。目前,关于半刚性节点的理论研究落后于工程实践,急待形成设计的理论体系,特别是需要建立弯矩和转角的本构方程用于工程设计。结合国内其他单位的研究成果,把本课题组从2000年至今5年来对半刚性理论与试验的研究进行总结分析,以推动实用理论的发展。     

地板砖火灾痕迹试验分析

以常见的全瓷釉面地板砖为例，对其火灾痕迹进行试验研究，分别就常温下机械破坏，高温下机械破坏，高温作用后自然冷却，高温作用后水冷，单面不均衡受热等多种情况进行模拟试验，通过对受热样品的宏观与微观形貌特征的观察和分析，寻找出不同温度、不同环境下，样品所表现出的不同的痕迹特征及其变化规律。     

Hardness and toughness improvement of SiC-based ceramics with the addition of (Hf0.2Mo0.2Ta0.2Nb0.2Ti0.2)B2

The influences of different contents ranging 0–15 wt% of high-entropy boride (HEB) (Hf_0.2Mo_0.2Ta_0.2Nb_0.2Ti_0.2)B₂ on the mechanical properties of SiC-based ceramics using Al₂O₃-Y₂O₃ sintering additives sintered by spark plasma sintering process were investigated in this study. The results showed that the introduction of 5 and 10 wt% (Hf_0.2Mo_0.2Ta_0.2Nb_0.2Ti_0.2)B₂ could facilitate the densification and the grain growth of SiC-based ceramics via the mechanism of liquid phase sintering. However, the grain growth of SiC-based ceramics was inhibited by the grain boundary pinning effect with the addition of 15 wt% (Hf_0.2Mo_0.2Ta_0.2Nb_0.2Ti_0.2)B₂. The SiC-based ceramics with 15 wt% (Hf_0.2Mo_0.2Ta_0.2Nb_0.2Ti_0.2)B₂ showed the enhanced hardness (21.9±0.7 GPa) and high toughness (4.88±0.88 MPa·m^1/2) as compared with high-entropy phase-free SiC-based ceramics, which exhibited a hardness of 16.6 GPa and toughness of 3.10 MPa·m^1/2. The enhancement in mechanical properties was attributed to the addition of higher hardness of HEB phase, crack deflection toughening mechanism, and presence of residual stress due to the mismatch of coefficient of thermal expansion.     

Large electrocaloric effect with ultrawide temperature span in Na1/2Bi1/2TiO3-based lead-free ceramics

Innovative cooling technologies are recognized by many industries as a crucial part of their system design. A large electrocaloric effect (ECE) and extended working temperature are the key issues hindering the realization of electrocaloric refrigeration technology. In this work, large ECE (ΔT = 0.8–0.9°C @ 4 kV/mm) with an ultrawide temperature span from 30 to 120°C is noted for lead-free (Na_1/2Bi_1/2)_0.80Sr_0.20(Zn_1/3Nb_2/3)_xTi_1-xO₃ ceramics. The excellent ECE performance can be ascribed to the evolution of polar nanoregions. Our work suggests that this material is promising for applications in solid-state refrigeration systems with a broad range of operating temperatures.     

Deep ocean bubble transport model coupled with multiple hydrate behavior characteristics

Submarine gas seepage is a widely observed process. In this study, a unified mechanistic model of bubble transport both inside and outside the gas hydrate stability zone (GHSZ) was developed. Multiple hydrate-related behaviors were considered, including hydrate nucleation, hydrate film lateral spread, hydrate shell dynamic growth, hydrate dissolution and decomposition, and collapse and fracture deformation of hydrate-coated bubbles. Using the proposed model, a series of simulation studies about bubble dissolution and rising fate were conducted. The results indicate that the formation of solid hydrates in the deep-sea environment can provide a fairly effective barrier for the dissolution and shrinkage of bubbles, and the deeper the initial release water depth, the smaller the critical size of the bubble required for arriving at the water surface. Furthermore, the majority of gases released from the seafloor would be absorbed by the shallow oceanic layer, but larger bubbles could still pass through the water column to the atmosphere.     

Sharpening polycrystalline phase boundary for potassium sodium niobate ceramics with MnF2 modification

The influence of anion on structure and performance is unclear in potassium sodium niobate ((K,Na)NbO₃; KNN)-based ceramics, while cation doping has been widely researched. Here, the phase structure and electrical properties are explored in MnF₂-doped KNN ceramics. Significantly, sharp rhombohedral–orthorhombic (R–O) and orthorhombic–tetragonal (O–T) phase boundary as well as reduced diffusion degree is exhibited in the ceramics along with little changed phase transition temperatures due to the optimized F⁻ content at O site, which is different from that of cation replacement for A and B sites. Notably, the domain wall motion is facilitated due to the increased A vacancy and decreased O vacancy along with strengthened polarity, originating from the higher valence state and electronegativity of F⁻ with respect to O²⁻. And then, enhanced ferroelectricity is realized via MnF₂ modification, the piezoelectricity is elevated in turn. This work presents a new idea of anion doping for controlling structure and properties in perovskite materials.     

酚醛泡沫的燃烧行为及阻燃研究进展

酚醛泡沫因兼具优异的保温性能和阻燃性能在工程领域得到广泛应用,但其经高温燃烧后质量残留率很低,炭层疏松、强度低,离开火焰后还易出现阴燃现象。目前有关酚醛泡沫燃烧行为的研究大多集中在如何进一步提高酚醛泡沫塑料的阻燃等级或在改善其脆性的同时不降低固有的阻燃性能,还未见关于酚醛泡沫燃烧全过程行为的综述报道。文章介绍了酚醛泡沫在明火燃烧和阴燃状态的燃烧行为,分析了影响酚醛泡沫燃烧行为的因素,并总结了现有酚醛泡沫阻燃研究的进展。目前酚醛泡沫的燃烧行为及阻燃研究主要集中在泡沫的明火燃烧,对酚醛泡沫阴燃问题的研究重视不足,缺乏针对酚醛泡沫燃烧全过程的行为和机理探究。因此,提出应加大对酚醛泡沫阴燃行为的研究投入,注重对酚醛泡沫燃烧全过程的机理探索与阻燃方案研究,设计并研发出解决酚醛泡沫燃烧全过程问题的有效途径。     

复配表面活性剂对油水界面行为和性质影响的模拟研究

含复配表面活性剂的油田废水是一种多组分复杂体系,研究其中的分子作用关系有助于后续废水处理方案的确定。采用分子动力学(MD)模拟方法建立界面模型,通过定义表面活性剂的关键扭转点及相应的分子夹角、定义协同作用能,结合界面处的密度分布函数等性能模拟和界面张力测试结果,多角度分析两类阴阳离子表面活性剂复配对油水界面特性的影响。结果表明,与含单组分表面活性剂的油水体系相比,复配表面活性剂的相反电荷极性头基间静电吸引作用提高了油水界面稳定性;相较于十二烷基磺酸钠/十六烷基三甲基溴化铵(SLS/CTAB)复配体系,十二烷基硫酸钠/十六烷基三甲基溴化铵(SDS/CTAB)中分子间的协同作用可更好地提高体系的稳定性;当复配表面活性剂的配比为8/10~12/6时的油/水界面稳定效果较优、12/6时稳定性最好。研究结果可为石油开采及油水分离方案的确定提供依据。