Graphene-Based Ultralight Compartmentalized Isotropic Foams with an Extremely Low Thermal Conductivity of 5.75 mW m−1 K−1

The importance of high-performance thermal insulation materials is rapidly emerging due to energy conservation and the management of temperature-sensitive device perspectives. Recent thermal insulation materials including complex structures have been developed either by reducing the structural connectivity to mitigate thermal transport through solid conduction or forming directionally aligned confined inner pores to suppress the internal gas convection. In this study, to create a highly efficient thermal insulating material that suppresses thermal transport in all directions, graphene-based anisotropic closed-cellular structures (CCS) are devised with a highly ordered assembly of hollow compartments with extremely thin walls (≈50 nm). This uniquely designed CCS made from microfluidically synthesized graphene solid bubbles exhibited a remarkably low thermal conductivity of 5.75 mW m⁻¹ K⁻¹ thanks to effective suppression of both solid conduction and gas conduction/convection. Therefore, the proposed strategy in this work offers a novel toolkit for implementing next-generation high-performance insulation materials.     

Prestoring Lithium into Stable 3D Nickel Foam Host as Dendrite‐Free Lithium Metal Anode

Lithium metal is considered a “Holy Grail” of anode materials for high‐energy‐density batteries. However, both dendritic lithium deposition and infinity dimension change during long‐term cycling have extremely restricted its practical applications for energy storage devices. Here, a thermal infusion strategy for prestoring lithium into a stable nickel foam host is demonstrated and a composite anode is achieved. In comparison with the bare lithium, the composite anode exhibits stable voltage profiles (200 mV at 5.0 mA cm^?2) with a small hysteresis beyond 100 cycles in carbonate‐based electrolyte, as well as high rate capability, significantly reduced interfacial resistance, and small polarization in a full‐cell battery with Li₄Ti₅O₁₂ or LiFePO₄ as counter electrode. More importantly, in addition to the fact that lithium is successfully confined in the metallic nickel foam host, uniform lithium plating/stripping is achieved with a low dimension change (merely ≈3.1%) and effective inhibition of dendrite formation. The mechanism for uniform lithium stripping/plating behavior is explained based on a surface energy model.     

机器人在塑料制造自动化中的技术应用及发展

随着科技的快速发展,诸多技术的涌现及其应用能够明显提升实际产业项目的运作效能,从而为企业管理效能与产品质量提供优质的保障。对于塑料制造加工而言,采取自动化技术来改善生产效率及其质量是极为明智的选择。通过研究塑料制造自动化流程中的技术手段,能够更为清晰地了解机器人在塑料制造自动化中的技术应用及其实际效能,从当前实践领域当中所观察到的机器人的应用状况来分析,机器人塑料制造自动化中的应用前景较为广阔,且值得在相关制造业领域中进行推广应用。本文就机器人在塑料制造自动化中的技术应用及发展进行深入探究,以期为同类型制造企业选用机器人提供有益的借鉴。     

基于数据模板匹配算法的FBG冲击定位系统

利用光纤Bragg光栅(FBG)构建传感网络,结合其频谱特性和数据模板匹配处理方法,对碳纤维复合材料(CFRP)板低速冲击区域定位进行了研究。对同一测点进行等能量两次冲击,结果表明,同一测点的两次冲击信号幅频特性之间具有高度相似度。改变冲击位置,观测冲击位置与信号特征之间的关系。依据冲击信号幅频特性,构建低速冲击数据模板库。采用数据模板匹配算法,寻找最大相似度,实现冲击位置识别。实验结果表明,在500mm×500mm×2mm的CFRP板上对任意10个待测点进行低速冲击试验,均实现了准确定位,区域定位精度为80mm×80mm。研究结果为CFRP板的冲击定位检测提供了一种可靠的方法。     

Constraining Si Particles within Graphene Foam Monolith: Interfacial Modification for High‐Performance Li+ Storage and Flexible Integrated Configuration

Pulverization of electrode materials and loss of electrical contact have been identified as the major causes for the performance deterioration of alloy anodes in Li‐ion batteries. This study presents the hierarchical arrangement of spatially confining silicon nanoparticles (Si NPs) within graphene foam (GF) for alleviating these issues. Through a freeze‐drying method, the highly oriented GF monolith is engineered to fully encapsulate the Si NPs, serving not only as a robust framework with the well‐accessible thoroughfares for electrolyte percolation but also a physical blocking layer to restrain Si from direct exposure to the electrolyte. In return, the pillar effect of Si NPs prevents the graphene sheets from restacking while preserving the highly efficient electron/Li⁺ transport channels. When evaluated as a binder‐free anode, impressive cycle performance is realized in both half‐cell and full‐cell configurations. Operando X‐ray diffraction and in‐house X‐ray photoelectron spectroscopy confirm the pivotal protection of GF to sheathe the most volume‐expanded lithiated phase (Li₁₅Si₄) at room temperature. Furthermore, a free‐standing composite film is developed through readjusting the pore size in GF/Si monolith and directly integrated with nanocellulose membrane (NCM) separator. Because of the good electrical conductivity and structural integrity of the GF monolith as well as the flexibility of the NCM separator, the as‐developed GF/Si‐NCM electrode showcases the potential use in the flexible electronic devices.     

泡沫对激光制导武器系统干扰效能分析

泡沫作为一种新兴的光电无源干扰手段,对激光制导武器干扰作用明显。首先对泡沫干扰进行了介绍,然后对激光制导武器系统的组成、制导原理进行了描述,探讨了利用泡沫干扰激光制导武器系统的可行性。并根据泡沫干扰及激光制导武器系统探测目标的要求,分别计算了激光制导武器系统的遮蔽面密度和泡沫两点间面密度,通过两种面密度的比较,对泡沫的干扰效能进行了分析。本文的研究结论对泡沫干扰效能评估及泡沫干扰战术的优化具有重要的意义。     

适用于大功率光电芯片散热的一体化平板热管

为解决大功率光电芯片散热问题,构造了一种新结构一体化平板热管。利用超轻多孔泡沫金属作为毛细吸液芯,以水、丙酮和乙醇为工质,在不同充液比、加热功率和倾角条件下对新结构热管的热性能进行了研究,结果表明,这种新结构平板热管不仅消除了热管与散热片间的接触热阻,而且使整个散热翅片也处于均温状态,当功率达到380W、热流密度超过445 W/cm2时,热管仍具有较好的均温特性,且热阻较小,可达0.04℃/W。在3种工质中,水是最佳工质选择,且当充液比为30%时具有较好的效果。实验表明,以泡沫金属为吸液芯的新结构一体化平板热管具有很好的传热性能,并扩展了承载大热流密度的能力。     

DYNAMIC CHANGES IN THE COMPOSITION AND PHYSICAL BEHAVIOUR OF DISPENSED BEER FOAM

Beer foam generated under conditions encountered at dispense was separated from beer, allowed to collapse and sampled at regular intervals. The yield of collapsed beer foam decreased logarithmically with time. Analysis of the composition of collapsed beer foam fractions over a period of time, considered to be relevant to actual consumption of beer (30 minutes) showed that polypeptide material and isomerised α acids were selectively partitioned in beer foam. The concentration of total polypeptides, soluble polypeptides, isomerised α acids and foam precipitate material in collapsed beer foam, firstly increased with foam collapse time and then approached maximal values. Under these conditions the concentration of polypeptide material and isomerised α acids increased 10–30 fold and 7 fold respectively as compared to beer. No evidence was obtained for the preferential partition of purine nucleosides and free bases in foam (adenosine + deoxyadenosine, guanosine + deoxyguanosine, adenine, guanine and xanthine).     

离子注入剂量对工程塑料表面纳米硬度的影响

研究了离子注入剂量和剂量率对工程塑料表面纳米硬度提高效果的影响，分别将不同剂量的C离子注入尼龙6和PET以及Al离子注入PPO，并将不同剂量率的Al离子注入PET。纳米硬度测量显示：随着注入剂量和剂量率的增加，尼龙6、PET、PPO的纳米硬度升高；未注入以及低剂量和剂量率注入塑料的载荷一位移曲线呈现弹塑性变形特征，而高剂量和剂量率注入的呈现出弹性变形特征。