光栅对石墨烯太赫兹光学性质的影响

在不考虑等离激元诱导效应的情况下，利用玻尔兹曼平衡方程方法从理论上研究了金属光栅结构对石墨烯光电导率的直接影响。研究发现由于光栅对入射光的动量补偿作用，光栅对石墨烯的带内光电导率产生了显著的影响，使得在石墨烯的太赫兹吸收窗口区域出现光电导率峰，并且该光电导率峰可由光栅周期、电子浓度以及温度来调控。该研究有助于深入理解光栅结构对光电材料的影响，并表明光栅-石墨烯体系可以应用于可调谐的太赫兹光电器件，如太赫兹探测器。     

利用Mathematica求解正轴圆锥投影的标准纬度

针对不同投影条件下的正轴圆锥投影标准纬度求解过程中遇到的数值迭代问题，借助 Mathematica 中的 FindRoot 函数，对涉及超越方程的标准纬度进行计算，得到了相应的数值解。 结果表明，利用 Mathematica 对不同正圆锥投影的标准纬度进行计算，求解过程简单、计算效率高且精度满足要求。     

Direct ink writing of vancomycin-loaded polycaprolactone/ polyethylene oxide/ hydroxyapatite 3D scaffolds

Novel inks were formulated by dissolving polycaprolactone (PCL), a hydrophobic polymer, in organic solvent systems; polyethylene oxide (PEO) was incorporated to extend the range of hydrophilicity of the system. Hydroxyapatite (HAp) with a weight ratio of 55–85% was added to the polymer-based solution to mimic the material composition of natural bone tissue. The direct ink writing (DIW) technique was applied to extrude the formulated inks to fabricate the predesigned tissue scaffold structures; the influence of HAp concentration was investigated. The results indicate that in comparison to other inks containing HAp (55%, 75%, and 85%w/w), the ink containing 65% w/w HAp had faster ink recovery behavior; the fabricated scaffold had a rougher surface as well as better mechanical properties and wettability. It is noted that the 65% w/w HAp concentration is similar to the inorganic composition of natural bone tissue. The elastic modulus values of PCL/PEO/HAp scaffolds were in the range of 4–12 MPa; the values were dependent on the HAp concentration. Furthermore, vancomycin as a model drug was successfully encapsulated in the PCL/PEO/HAp composite scaffold for drug release applications. This paper presents novel drug-loaded PCL/PEO/HAp inks for 3D scaffold fabrication using the DIW printing technique for potential bone scaffold applications.     

移动边缘计算中资源分配和定价方法综述

移动边缘计算（mobile edge computing,MEC）通过将计算任务卸载至边缘服务器，降低网络负荷，减少传输时延，提升用户服务体验。因此，MEC受到了广泛关注，并成为5G的关键技术。资源分配作为MEC的主要问题，在提升能量效率、缩短任务时延和节约成本方面具有非常重大的研究意义。首先，介绍了MEC的基本概念、参考架构和技术优势；然后，从技术层面和经济层面归纳总结了MEC中最新的资源分配和定价策略；最后，讨论了MEC资源分配和定价策略中可能存在的问题与挑战，并提出了一些可行的解决方案，为后续研究发展提供参考。     

水力空化改质对重质原油沥青质及性质的影响

利用水力空化过程产生局部的高温、高压、高射流以及强大的剪切力等极端化学物理条件改质处理沙特重质原油，试验结果表明：沙特重质原油经过水力空化改质后粘度由13.61降低至7.22mm2/s，残碳由7.16%降低至6.48%，实沸点蒸馏后减压渣油降低1个百分点。进一步采用APPI FT-IR MS、XRD、FT-IR、SEM和粒度分布等技术研究了水力空化改质对沙重原油分子组成，沥青质团聚体微晶结构、沥青质胶束粒径分布、沥青质官能团、沥青质形貌等方面的影响，从分子角度阐述空化改质重油的机理。研究结果表明：水力空化改质后沙重原油分子量分布、芳烃类化合物缔合作用变小；沥青质对低DBE化合物吸附性能降低；沥青质团聚体微晶结构更加松散；沥青质胶束粒度分布降低；沥青质分子相互团聚作用力减弱。进一步考察了水力空化改质前后减压渣油延迟焦化性能，改质处理后焦炭产率降低1.85个百分点，液体收率和气体产率分别增加1.52和0.33个百分点，水力空化改质对沥青质性质、结构特点的改善能够有效的提高其加工性能。     

Ensemble relation network with multi-level measure

Fine-grained few-shot learning is a difficult task in image classification. The reason is that the discriminative features of fine-grained images are often located in local areas of the image, while most of the existing few-shotlearning image classification methods only use top-level features and adopt a single measure. In that way, the localfeatures of the sample cannot be learned well. In response to this problem, ensemble relation network with multi-level measure (ERN-MM) is proposed in this paper. It adds the relation modules in the shallow feature space tocompare the similarity between the samples in the local features, and finally integrates the similarity scores from thefeature spaces to assign the label of the query samples. So the proposed method ERN-MM can use local details andglobal information of different grains. Experimental results on different fine-grained datasets show that the proposedmethod achieves good classification performance and also proves its rationality.     

基于人工神经网络的智能化架空线路应变快速解调方法北大核心

为了提高智能化光纤复合架空线路态势感知的实时性,将人工神经网络方法应用于光纤沿线应变解调,确定了神经网络的结构。编程实现了基于洛伦兹模型的最小二乘谱拟合方法和神经网络方法,采用不同信噪比和布里渊频移的布里渊谱训练神经网络,将它们应用于某光纤复合架空线路沿线光纤应变的测量,从不同角度比较了两种方法的计算结果。计算结果表明,神经网络方法能有效获得光纤沿线的布里渊频移进而获得应变,具有与谱拟合方法相似的准确性,但应变解调时间仅约为谱拟合方法的1/20000。研究结果为提高智能光纤复合架空线路态势感知的实时性提供了参考。