硅酸锆超细粉碎生产中粒度分布测量方法比较

主要论述了硅酸锆超细粉粒度分布的3种不同测量方法,结合生产实际比较了它们的测量原理及优缺点。     

非线性部件的轴系动稳态响应研究

对有局部非线性的船舶推进轴系振动稳态响应进行理论和试验研究。在考虑联轴器非线性刚度和阻尼的情况下 ,以GLM (Galerkin Levenberg Marquardt)法为基础 ,提出一种分离变换法并编制相应计算程序。用此方法及程序对一单圆盘轴系振动稳态响应进行计算并进行试验。结果表明 ,计算所获振动稳态响应时间历程与试验所获振动稳态响应时间历程吻合好。     

面向自然语言处理的对抗攻防与鲁棒性分析综述

随着人工智能技术的飞速发展,深度神经网络在计算机视觉、信号分析和自然语言处理等领域中都得到了广泛应用.自然语言处理通过语法分析、语义分析、篇章理解等功能帮助机器处理、理解及运用人类语言.但是,已有研究表明深度神经网络容易受到对抗文本的攻击,通过产生不可察觉的扰动添加到正常文本中,就能使自然语言处理模型预测错误.为了提高模型的鲁棒安全性,近年来也出现了防御相关的研究工作.针对已有的研究,全面地介绍自然语言处理攻防领域的相关工作,具体而言,首先介绍了自然语言处理的主要任务与相关方法;其次,根据攻击和防御机制对自然语言处理的攻击方法和防御方法进行分类介绍;然后,进一步分析自然语言处理模型的可验证鲁棒性和评估基准数据集,并提供自然语言处理应用平台和工具包的详细介绍;最后总结面向自然语言处理的攻防安全领域在未来的研究发展方向.     

5083铝合金搅拌摩擦焊接头拉伸行为研究

目的 研究5083铝合金搅拌摩擦焊接（FSW）的组织、力学性能和拉伸应变,分析接头的拉伸行为。方法 采用数码相机、光学显微镜、电子扫描显微镜等表征分析方法,对焊缝的表面宏观成形、微观组织、断口形貌进行分析;利用拉伸机、三维数字动态散斑应变测量分析系统和显微维氏硬度计对接头的力学性能和拉伸应变进行测试。结果 不同焊接工艺参数下FSW接头的最低抗拉强度为305 MPa,断后延伸率达到了14%以上;焊核区拉伸应变沿板厚方向呈现上高下低和上宽下窄的不均匀梯度分布,发生了较大程度的变形强化,直到拉伸应力达到抗拉强度。断裂失效前300/120接头的最大拉伸应变在晶粒粗大的母材区,500/120和500/200接头的最大拉伸应变则位于晶粒尺寸差异较大的后退侧焊核区与热力影响区交界处。接头拉伸断口宏观上均为45°剪切韧性断裂,微观上均以韧窝韧性断裂为主,而高热输入500/120接头出现脆性断裂特征,其延伸率明显降低。结论 高热力耦合输入使铝合金FSW接头薄弱区发生转变,强韧性降低。     

热释电系数测试系统

对铁电薄膜所具有的铁电、热释电特性进行了研究,在此基础上设计出了热释电系数测试系统。ｐＡ级电流放大器是测试系统的设计重点,而其输入阻抗、运算精度及噪声抑制又是设计关键。简要介绍了测试系统的设计思路、组成及工作原理。用所设计的测试系统对ＰＬＴ薄膜样品进行了测试,测试结果表明,溶胶－凝胶工艺制备的ＰＬＴ薄膜样品的热释电电流平均值为２．１×１０－１１Ａ而对应的热释电系数ｐ为２．５２×１０－８Ｃ／ｃｍ２°Ｃ。     

静电纺多级结构空气过滤材料的研究进展

为促进静电纺纳米纤维在空气过滤领域中的应用,开发性能更加优异的新型纳米纤维空气过滤膜,以近年来国内外静电纺丝技术制备多级结构纳米空气过滤材料的相关研究为基础,综述了静电纺制备具有微纳米凸起、纳米蛛网、层层复合、多孔、刺状、树枝状及核壳等结构空气过滤材料的最新研究进展,分析和讨论了多级结构微纳米空气过滤材料的制备方法,指出了现有研究中存在的不足,并对未来的发展方向进行了总结和展望。认为多级结构可有效实现过滤材料高效率、低阻力、高强度、阻燃等的功能化,相较于传统的纳米纤维过滤材料具有更好的应用前景。     

基于旅游者和日常访问者人群行为的城市型景区“共处”空间研究

针对城市型景区内旅游者和日常访问者相互影响的现象,提出"共处"空间概念,从"空间-行为"关系视角总结"共处"空间的时空特性,形成"共处"空间判别依据。基于计算机视觉技术,通过问卷调查,将人群行为划分为互不干扰、围观及参与、干扰及冲突3类,从空间优化与管理角度对列入公园年票体系中的城市型景区提出建议,梳理2类人群关系,提高游憩体验质量。     

Propionibacterium acnes Cloaked with ZnAl Layered Double Hydroxides Synergistically Inhibits Tumor Growth and Metastasis

The combination of precise tumor depletion and immunotherapy presents great potential to exterminate cancer disease. Anaerobic bacteria can trigger innate and adaptive immune responses in tumors to facilitate the antitumor effects. However, bacteria injected intravenously induce systemic inflammation and are likely to be eliminated in the blood. Herein, live bacteria, Propionibacterium acnes (P. acnes), are integrated with ZnAl layered double hydroxides (LDHs) to construct an effective system enabling synergistic inhibition in both tumor growth and metastasis. In this system, P. acnes carries LDHs to reach and penetrate the hypoxic tumor tissue. The metabolism of colonized P. acnes and the pH-responsive degradation of LDHs produce reactive nitrogen species and reactive oxygen species to trigger inevitable cell death. Furthermore, the decomposition of LDHs exposes P. acnes, and thus the immune response is activated to prohibit the reoccurrence of distant tumors. The biohybrid P. acnes@LDHs, developed in this study, possesses remarkable anticancer outcomes both in vitro and in vivo.     

Moisture-Thermal Stable,Superhydrophilic Alumina-Based Ceramics Fabricated by a Selective Laser Sintering 3D Printing Strategy for Solar Steam Generation

The solar-driven interface evaporation is one of the most promising technologies for desalination and wastewater purification. However, in the ebb and flow of the tide, water absorbed in the hydrophilic evaporator bottom would significantly change, leading to the shape deformation of the system and further failure of solar steam generation. Here it is reported that the moisture-thermal stable and superhydrophilic alumina-based ceramics can be fabricated by a selective laser sintering (SLS) 3D printing strategy. The printed alumina-based ceramics possess superhydrophilicity. Along the side surface of the printed sample, a 5 µL water droplet can be fast absorbed in 14 ms. Most importantly, they can maintain stable and high evaporation efficiency even after being dried out for ten times, demonstrating the excellent physical resistance to continuous moisture-thermal transition. Finally, the “I-shaped” evaporators are printed with salt-resistant ability, which can maintain a steady high evaporation efficiency in seawater and 20 wt% brine for long-term steam generation process. The moisture-thermal stable alumina-based ceramics prepared in this work will provide inspiration for stable solar steam generation materials, and expand the development of 3D printing functional materials.