Locking-free triangular plate element using polynomial incompatible approximation for analysis of cracked thick–thin plates

This work describes a new filament deposition in fused deposition modeling process through criterion based on mechanical stress. This criterion requires that the filaments’ directions to follow the principal directions of the stress in the sample. The article also presents several Crack-test specimens that have been printed with and without respect to this criterion. The fracture behavior of these specimens has been investigated. The results show that criterion leads to an improvement of 30% in the fracture toughness. Digital image correlation has been extensively used to study the local strain field in the specimens. The strain cartographies reveal a drastic change in fracture behavior. The modification of filament direction leads to “ductile-like behavior” in crack extension which is characterized by a large deformation zone associated with a slow crack growth rate during the crack propagation.     

Graphitic nanorings for super-long lifespan lithium-ion capacitors

Porous graphitic carbon nanorings (PGCNs) are proposed by smart catalytic graphitization of nano-sized graphene quantum dots (GQDs). The as-prepared PGCNs show unique ring-like morphology with diameter around 10 nm, and demonstrate extraordinary mesoporous structure, controllable graphitization degree and highly defective nature. The mechanism from GQDs to PGCNs is proven to be a dissolution-precipitation process, undergoing the procedure of amorphous carbon, intermediate phase, graphitic carbon nanorings and graphitic carbon nanosheets. Further, the relationship between particles size of GQDs precursor and graphitization degree of PGCNs products is revealed. The unique microstructure implies PGCNs a broad prospect for energy storage application. When applied as negative electrode materials in dual-carbon lithium-ion capacitors, high energy density (77.6 Wh·kg⁻¹) and super long lifespan (89.5% retention after 40,000 cycles at 5.0 A·g⁻¹) are obtained. The energy density still maintains at 24.5 Wh·kg⁻¹ even at the power density of 14.1 kW·kg⁻¹, demonstrating excellent rate capability. The distinct microstructure of PGCNs together with the strategy for catalytic conversion from nanocarbon precursors to carbon nanorings opens a new window for carbon materials in electrochemical energy storage.

     

基于卷积神经网络的电力系统小干扰稳定评估

随着电力系统规模的增大,通过传统数值方法计算系统特征值来进行小干扰稳定评估已无法满足实时分析的要求。因此,提出了一种基于深度学习(卷积神经网络)的电力系统小干扰稳定评估方法。该方法以广域测量系统可监测变量作为模型的输入,关键特征值作为输出,对输入数据和输出数据进行相应处理后,利用深层架构对其映射关系进行分析;并针对大系统维数较高、训练速度较慢的问题,采用了离散余弦变换和图形处理器并行技术。算例结果表明,在不考虑控制参数变化的情况下,经过历史数据的离线训练后,该方法能够较准确地计算出系统的关键特征值。     

面向快速制模的机器人铣削原型工艺研究

机器人快速制造原型是正在发展的一种快速制造原型和零件的方法,但是它的应用范围目前仅局限于石蜡、木材、塑料和轻金属等材料。本文开发了一种机器人快速铣削制造陶瓷材料原型的工艺,并成功用于机器人快速制造金属模具工艺。试验研究了适用于该工艺的陶瓷原型材料、陶瓷原型铣削制造工艺以及机器人的铣削特性。从而扩展了机器人原型制造的可加工材料范围以及快速原型制造的应用领域。     

Plasmonic Metallic Heteromeric Nanostructures

Binary, ternary, and other high‐order plasmonic heteromers possess remarkable physical and chemical properties, enabling them to be used in numerous applications. The seed‐mediated approach is one of the most promising and versatile routes to produce plasmonic heteromers. Selective growth of one or multiple domains on desired sites of noble metal, semiconductor, or magnetic seeds would form desired heteromeric nanostructures with multiple functionalities and synergistic effects. In this work, the challenges for the synthetic approaches are discussed with respect to tuning the thermodynamics, as well as the kinetic properties (e.g., pH, temperature, injection rate, among others). Then, plasmonic heteromers with their structure advantages displaying unique activities compared to other hybrid nanostructures (e.g., core–shell, alloy) are highlighted. Some of the main most recent applications of plasmonic heteromers are also presented. Finally, perspectives for further exploitation of plasmonic heteromers are demonstrated. The goal of this work is to provide the current know‐how on the synthesis routes of plasmonic heteromers in a summarized manner, so as to achieve a better understanding of the resulting properties and to gain an improved control of their performances and extend their breadth of applications.     

Achieving Highly Efficient Nonfullerene Organic Solar Cells with Improved Intermolecular Interaction and Open‐Circuit Voltage

A new acceptor–donor–acceptor‐structured nonfullerene acceptor ITCC (3,9‐bis(4‐(1,1‐dicyanomethylene)‐3‐methylene‐2‐oxo‐cyclopenta[b]thiophen)‐5,5,11,11‐tetrakis(4‐hexylphenyl)‐dithieno[2,3‐d′:2,3‐d′]‐s‐indaceno[1,2‐b:5,6‐b′]‐dithiophene) is designed and synthesized via simple end‐group modification. ITCC shows improved electron‐transport properties and a high‐lying lowest unoccupied molecular orbital level. A power conversion efficiency of 11.4% with an impressive V _OC of over 1 V is recorded in photovoltaic devices, suggesting that ITCC has great potential for applications in tandem organic solar cells.     

Rational Tuning of Molecular Interaction and Energy Level Alignment Enables High‐Performance Organic Photovoltaics

The performance of organic photovoltaics (OPVs) has rapidly improved over the past years. Recent work in material design has primarily focused on developing near‐infrared nonfullerene acceptors with broadening absorption that pair with commercialized donor polymers; in the meanwhile, the influence of the morphology of the blend film and the energy level alignment on the efficiency of charge separation needs to be synthetically considered. Herein, the selection rule of the donor/acceptor blend is demonstrated by rationally considering the molecular interaction and energy level alignment, and highly efficient OPV devices using both‐fluorinated or both‐nonfluorinated donor/acceptor blends are realized. With the enlarged absorption, ideal morphology, and efficient charge transfer, the devices based on the PBDB‐T‐F/Y1‐4F blend and PBDB‐T‐F/Y6 exhibit champion power conversion efficiencies as high as 14.8% and 15.9%, respectively.     

由高岭土制备聚合氯化铝反应器计算

酸浸法是利用高岭土生产铝盐产品及其深加工产品的基本方法。盐酸浸取高岭土中的氧化铝是制备聚合氯化铝的基础反应，通常采用间歇反应器进行反应。文章以酸浸反应动力学为基础，研究反应器体积的计算方法。影响反应器体积大小的主要因素有物料浓度、氧化铝浸出率、反应温度和反应时间等。对诸因素应加以综合考虑，选择适宜的操作条件十分重要。     

带单排气膜孔导向叶片前缘气膜冷却实验研究

针对导向叶片前缘结构的特点,建立了前缘气膜冷却实验台,实验模型由半圆柱面和2个平板组成,在距离滞止线2倍气膜孔直径位置布置了1排气膜孔.详细地测量了动量比对前缘径向平均换热系数和冷却效率的影响.二次流与主流密度比为1.5.动量比变化范围为0.5～4.主流在前缘位置的湍流度为0.4%和8%.研究结果表明,随着动量比的增加,换热系数增加,冷却效率减小.低动量比时气膜冷却使热负荷减少,高动量比时气膜冷却使热负荷增加.     

储能参与电力系统快速调频的需求评估方法

随着特高压直流建设和可再生能源发展,直流闭锁故障对电力系统快速调频提出了挑战。针对储能技术改善电力系统频率稳定性,提出了一种储能参与系统快速调频的需求评估方法。首先提出了电力系统快速调频的瓶颈评估指标和瓶颈场景分析方法,为储能容量配置提供了场景基础;接着又提出了基于瓶颈边界场景的储能容量优化配置方法,以最小化储能容量配置成本消除电力系统快速调频的瓶颈场景;最后基于江苏电网实际数据进行了算例分析,结果验证了所提出的需求评估方法的有效性。