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1.
数学均匀化方法是计算周期复合材料结构的有效方法之一,单胞边界条件施加的合理性直接决定了影响函数控制方程的计算效率和精度,进而影响均匀化弹性参数和摄动位移的计算精度.本文首先将单胞影响函数作为虚拟位移处理,给出了单胞在结构中真实的边界条件,结果表明,四边固支适合作为二维结构单胞边界条件;其次,针对二维结构提出了超单胞周期边界条件,有效提高了影响函数的计算精度,并使用与虚拟位移相对应的虚拟势能泛函验证超单胞周期边界条件的有效性;最后,利用数值分析验证多尺度渐进展开方法的计算精度,强调了二阶摄动的必要性.  相似文献   
2.
介绍了一种使用钢环和碳纤维复合材料环共同预紧方式的两面顶超高压模具,该结构在全钢环两面顶模具的基础上,使用一层碳纤维复合材料环代替最外层钢环,得到了一种具有碳纤维复合材料环的超高压模具。这种设计避免了大直径钢环难以制造加工的问题,形成一种以钢环与复合材料环共同对压缸预紧的新型预紧方式。数值分析表明:该模具结构设计具有可行性,可以在一定程度上减小压缸的周向应力、最大剪切应力和等效应力。此外,对碳纤维复合材料环进行了失效判别。  相似文献   
3.
多功能器件的设计是推动新一代电磁系统发展的重要力量,而超构表面因其对电磁波的幅度、相位和极化等特性的灵活调控在多功能器件领域备受关注.传统的多功能超构表面是利用各向异性单元对相互正交的线极化波具有不同响应的特性,从而设计出适用于线极化的多功能器件.本文提出了一种缝隙加载的环I形复合超构表面单元,通过单元臂长和旋转角度的调整实现了对圆极化电磁波传输和几何相位的独立控制.利用上述两种相位的共同作用,打破了左旋和右旋圆极化电磁波操控中存在的固有关系,为圆极化双功能器件的设计提供了新的思路.在此基础上,利用复合超构表面分别设计了异面偏折器和定向/涡旋光束产生器,实验结果表明,本文设计的两种反射型圆极化双功能器件在9—13 GHz的宽频带范围内均能良好工作.  相似文献   
4.
Nanofiltration has been attracting great attention in alleviating the global water crisis because of its high efficiency,mild operation,and strong adaptability.Over decades,it remains a challenge to break the upper limit of performance and establish the formation-structureproperty relationship for nanofiltration membranes.This feature article summarizes our recent progress in the preparation of high-performance thin-film composite(TFC)nanofiltration membranes,focusing on the mussel-inspired deposition method and the optimized interfacial polymerization(IP).By accelerating the oxidation of polydopamine and equilibrating the rate of aggregation and deposition processes,the mussel-inspired deposition method realizes the rapid and uniform formation of selective coatings or nanofilms.Diverse deposition systems endow the selective layer with rich chemical structures and easy post-functionalization,highlighting its potential in water treatment.As for optimizing the conventional IP,the rapid polycondensation of amine and acid chloride groups is slowed down to enable the controllability of IP at the water-organic interface.The homogeneity and integrity of the TFC membranes are improved by constructing a uniform reaction platform and introducing a viscous medium to control the amine diffusion,which facilitates the water permeability and promotes the separation efficiency.We have proposed a series of practical strategies for improving TFC membranes and might provide more inspiration for other nanofiltration techniques.  相似文献   
5.
《Mendeleev Communications》2022,32(4):520-522
Investigations of nanocomposite thin films based on polyarylene- phthalide, single-walled carbon nanotubes and graphene oxide have been carried out. Using these films as a transport layer, field-effect transistors were assembled and their output and transfer characteristics were measured. The mobility of charge carriers was estimated and the obtained values are as follows: μPAP/GO = 0.020 cm2 V?1 s?1 and μPAP/SWCNT = 0.071 cm2 V?1 s?1.  相似文献   
6.
A novel solvent terminated microextraction method based on a natural deep eutectic solvent (L-menthol and lactic acid at a molar ratio of 1:2) coupled with high-performance liquid chromatography was proposed, which was utilized for the separation and enrichment of bisdemethoxycurcumin, demethoxycurcumin and curcumin in Curcumae Longae Rhizoma and turmeric tea. The effects of independent parameters on extraction efficiency were optimized by single-factor analysis. Subsequently, four predominated parameters affecting the extraction procedure, including extractant volume, salt concentration, demulsifier consumption, and demulsification time, were further evaluated by a central composite design. Under the optimized conditions, the linear ranges of calibration curves were 0.005–0.5 μg/mL for bisdemethoxycurcumin, 0.004–0.4 μg/mL for demethoxycurcumin, and 0.0045–0.45 μg/mL for curcumin, respectively. In addition, the developed method provided low detection limits (0.1–0.4 ng/mL) and high enrichment factors (279–350). Its intra-day and inter-day precision were carried out by relative standard deviation ranging from 2.2 to 9.2%. Finally, the applicability of this method was assessed by the analysis of Curcumae Longae Rhizoma and turmeric tea samples. The results showed that these samples were detected successfully and the spiked recoveries over the range of 85.3-108.9% with relative standard deviations of 1.6-8.9% were attained, indicating its high relative recoveries with good precision in real sample analysis.  相似文献   
7.
金属锂作为电池的负极材料具有极高的比容量和极低的氧化还原电位,能够显著提升电池的能量密度。然而,金属锂负极在实际应用中所面临的主要问题是锂枝晶、界面副反应和电极体积变化大的难题。在本文中,我们提出了一种通过将定量的金属锂与三维骨架进行复合形成三维泡沫锂负极的策略,并利用三维泡沫锂来抑制锂枝晶的生长和缓解电极的体积变化。因此,三维泡沫锂电极有利于金属锂负极的高效利用,并能借助其与平面锂箔相比更高的比表面积和更多的反应位点来提升电池的倍率性能。因此,通过采用三维泡沫锂,对称电池的循环寿命和倍率性能都得到了有效的提升。EIS数据结果表明,三维泡沫锂能够减小对称电池的电荷转移阻抗。而且,将三维泡沫锂作为负极组装的LTO全电池,与锂箔作为负极相比,循环1000周平均放电比容量从65 mAh·g-1提升至121 mAh·g-1。  相似文献   
8.
The carbon composite materials have been a research hotspot in the fields of catalysis, energy conversion and so on, because of their features of large structure and morphology variety, good chemical and electrochemical stability, and high electronic conductivity, large specific surface area and rich active sites. This paper summarizes some research progress of carbon composite materials, including assembly methodologies, their structure regulation, properties, and related applications. Moreover, the current challenges and the prospects of these materials are also discussed.  相似文献   
9.
制备了一种具有过氧化物酶活性的类普鲁士蓝/氧化石墨烯复合纳米材料(CoFe(Ⅲ)PBA/GO)。将具有过氧化物酶活性的CoFe(Ⅲ)PBA/GO和化学发光法相结合,构建了一种用于检测H2O2和抗坏血酸(AA)的化学发光分析法。CoFe(Ⅲ)PBA/GO催化H2O2产生的O2·-,·OH,1O2自由基氧化Luminol会产生很强的化学发光信号,通过检测化学发光强度可以实现对H2O2的检测。该方法检测H2O2的线性范围为0~0.8μmol/L,检测限为11 nmol/L。利用AA作为活性氧消除剂可以抑制化学发光反应的特点,实现了AA的检测。该方法测定AA的线性范围为0.02~0.8μmol/L,检测限为20 nmol/L。方法已应用于H2O2消毒水中H2O2和维生素C片中抗坏血酸的检测。  相似文献   
10.
4D printing is an exciting branch of additive manufacturing. It relies on established 3D printing techniques to fabricate objects in much the same way. However, structures which fall into the 4D printed category have the ability to change with time, hence the “extra dimension.” The common perception of 4D printed objects is that of macroscopic single-material structures limited to point-to-point shape change only, in response to either heat or water. However, in the area of polymer 4D printing, recent advancements challenge this understanding. A host of new polymeric materials have been designed which display a variety of wonderful effects brought about by unconventional stimuli, and advanced additive manufacturing techniques have been developed to accommodate them. As a result, the horizons of polymer 4D printing have been broadened beyond what was initially thought possible. In this review, we showcase the many studies which evolve the very definition of polymer 4D printing, and reveal emerging areas of research integral to its advancement.  相似文献   
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