Effect of Vacancy Defects on the Young's Modulus and Fracture Strength of Graphene: A Molecular Dynamics Study

The Young's modulus of graphene with various rectangular and circular vacancy defects is investigated by molecular dynamics simulation. By comparing with the results calculated from an effective spring model, it is demonstrated that the Young's modulus of graphene is largely correlated to the size of vacancy defects perpendicular to the stretching direction. And a linear reduction of Young's modulus with the increasing concentration of mono‐atomic‐vacancy defects (i.e., the slope of ?0.03) is also observed. The fracture behavior of graphene, including the fracture strength, crack initiation and propagation are then studied by the molecular dynamics simulation, the effective spring model, and the quantized fracture mechanics. The blunting effect of vacancy edges is demonstrated, and the characterized crack tip radius of 4.44 Å is observed.     

二维分数阶Volterra积分方程的修正block-by-block方法

基于经典block-by-block方法的思想,构造了二维分数阶Volterra积分方程的一个修正block-by-block数值求解格式.该方法的优点在于只需求解u(x1,y),u(x2,y),u(x,y_1)和u(x,y_2),其他未知量均不需要耦合求解.数值算例表明该格式具有较好的逼近性.     

自动化测试技术在Web EDI系统中的应用

传统汽车供应链和医疗保健行业这些系统中的数据信息量都很大,通常会使用EDI系统平台进行数据消息的存储、收发和分享。如何快速、批量地添加Web EDI系统所需的报文数据供测试使用,并验证其正确性是个重点。通过XML来描述EDI报文信息,设计脚本批量生成测试数据,并导入Supply Online平台,对展示的信息自动进行正确性验证。在已有开源工具Selenium和Junit测试框架上进行改进,结合Web Driver、Maven与Test NG搭建一个自动化测试框架,快速、便捷地实现大数据量的创建、查询、验证等功能的自动化工作,有效加快项目进度,节省人力资源成本,缩减冗余时间,降低日常开支,提高生产力。     

A Visual Lossless Image-Recompression Framework

In this paper, we propose a novel image recompression frame?work and image quality assessment (IQA) method to efficient?ly recompress Internet images. With this framework image size is significantly re...     

吸收型雷达无源干扰材料研究进展与应用

分析了传统无源干扰装备在作战使用中存在的局限性,指出了吸收型无源干扰材料研究的必要性。详细介绍了泡沫云、膨胀石墨、改性纤维、吸收型箔条等几种吸收型无源干扰材料的性能及研究现状,并指出目前吸收型无源干扰材料在波段覆盖、战术应用以及工程化制备等方面仍存在一定缺陷,需进一步研究探索。