Machine learning powered ellipsometry

Ellipsometry is a powerful method for determining both the optical constants and thickness of thin films. For decades, solutions to ill-posed inverse ellipsomet...     

关于异黄酮类化合物精制方法的探讨

简单介绍了异黄酮类化合物的结构、性质,着重对吸附法、超滤膜法、溶剂提取（萃取）法、色谱法、重结晶法等异黄酮精制方法的特点和应用情况进行了综述。     

深度双重注意力的生成与判别联合学习的行人重识别

在行人重识别任务中存在数据集标注难度大,样本量少,特征提取后细节特征缺失等问题。针对以上问题提出深度双重注意力的生成与判别联合学习的行人重识别。首先,构建联合学习框架,将判别模块嵌入生成模块,实现图像生成和判别端到端的训练,及时将生成图像反馈给判别模块,同时优化生成模块与判别模块。其次,通过相邻的通道注意力模块间连接和相邻空间注意力模块间连接,融合所有通道特征和空间特征,构建深度双重注意力模块,将其嵌入教师模型,使模型能更好地提取行人细节身份特征,提高模型识别能力。实验结果表明,该算法在Market-1501和DukeMTMC-ReID数据集上具有较好的鲁棒性、判别性。     

混合梯度稀疏先验约束下的图像盲复原

图像盲复原旨在无参考的情况下准确估计模糊核并恢复潜在的清晰图像。现有研究成果表明,利用全变分模型对高阶图像梯度先验约束进行描述可以有效抑制复原图像中产生的阶梯效应。本文在实验观察和研究的基础上,提出了采用稀疏先验约束模型对盲复原过程进行正则化的方法,以获得更佳的图像复原效果。该方法利用图像高阶梯度的稀疏性,通过与低阶梯度相结合来构造混合梯度正则项。同时,在正则项中引入基于图像熵的自适应因子,来调节迭代优化过程中两类梯度先验的比例,以此获得更好的收敛性。仿真与实验证明,与现有图像盲复原先进方法相比,本文方法具有更优越的图像复原性能。     

Advances and Challenges in Two?Dimensional Organic–Inorganic Hybrid Perovskites Toward High?Performance Light?Emitting Diodes

Two-dimensional (2D) perovskites are known as one of the most promising luminescent materials due to their structural diversity and outstanding optoelectronic p...     

Study on Thermal Deformation Behavior and Properties of Vacuum Hot-press Sintered W(50)/Cu-Al_2O_3 Composite

In this work, the tungsten particulate reinforced Al2O3 dispersion strengthened copper base composites were successfully fabricated by using a vacuum hot-press sintering method. With the test temperature varying from 650 to 950 ℃ and the strain rate varying from 0.01 to 5 s-1, the W(50)/Cu-Al2O3 composites were isothermally compressed on a Gleeble-1500D thermal simulator. The true stress-strain curves of the W(50)/Cu-Al2O3 under different test conditions were obtained. The dynamic recrystallization of the W...     

Salt Concentration Effects in Planar Light‐Emitting Electrochemical Cells

Incorporation of ions in the active layer of organic semiconductor devices may lead to attractive device properties like enhanced injection and improved carrier transport. In this paper, we investigate the effect of the salt concentration on the operation of light‐emitting electrochemical cells, using experiments and numerical calculations. The current density and light emission are shown to increase linearly with increasing ion concentration over a wide range of concentrations. The increasing current is accompanied by an ion redistribution, leading to a narrowing of the recombination zone. Hence, in absence of detrimental side reactions and doping‐related luminescence quenching, the ion concentration should be as high as possible.     

Thermal conductivity measurement of the epoxies and composite material for low temperature superconducting magnet design

The thermal conductivities of solid materials were measured by a G-M cryo-cooler based apparatus in the temperature range of 2.6–21.0 K. The performance of this apparatus was verified by measuring the thermal conductivity of 304-stainless steel, and good reproducibility as well as accuracy was shown when compared with the certified values. The thermal conductivities of EC1017 and Stycast2850FT and a composite material were measured. Similar behavior to amorphous materials was shown for EC1017 and Stycast2850FT in that there was an apparent plateau, which could be ascribed to a very lower crystallinity of epoxy. An equivalent model was proposed to predict the thermal conductivity of the composite material.     

Interface-dependent resistance switching in Nd<Subscript>0.7</Subscript>Sr<Subscript>0.3</Subscript>MnO<Subscript>3</Subscript> ceramics

Interface-dependent electric-pulse-induced resistance switching effect (EPIR) in Nd_0.7Sr_0.3MnO₃ ceramics was studied. The results reveal that the EPIR effect originates from the interface between the electrodes and the bulk, and the EPIR ratio as well as the high and low resistance states can be strongly influenced by applying a large electrical field on the sample for different intervals. Also, the pulse parameters have great effect on the stability of EPIR and the optimal pulse width, pulse amplitude and read bias are obtained. Based on the space charge limited current mechanism together with the theory of interfacial charge-trapped state, the interface-dependent resistance switching effect is discussed.     

Effect of grain refinement on corrosion of ferritic–martensitic steels in supercritical water environment

The effects of grain refinement on the corrosion behavior of three ferritic–martensitic (F/M) steels, HT9, T91, and NF616, and two binary model alloys Fe‐15%Cr and Fe‐18%Cr in supercritical water (SCW) have been investigated. Grain refinement down to a size of about one micron in the surface regions, was achieved by introducing severe plastic deformation by shot peening. After exposure to SCW with 25 ppb oxygen at 500 °C for up to 3000 h, an improvement in corrosion resistance was observed in grain‐refined samples because of the enhanced diffusion of chromium on the surface, through a high density of grain boundaries. The chromium content in the steels and the exposure durations in SCW were determined to be important factors influencing the efficacy of the grain refinement effects. These results are supported by both experimental evidence and theoretical predictions. Another approach for grain refinement, equal channel angular pressing (ECAP), was also investigated for T91 steel. ECAP resulted in lower weight gain due to corrosion compared to the untreated samples, but exhibited a slightly higher weight gain compared to the shot‐peened samples after long‐term exposures in SCW which is probably caused by different fractions of high‐angle grain boundaries in grain‐refined regions, introduced by different grain refinement techniques.