Adiabatic Terminator for Fermionic Hierarchical Equations of Motion

The hierarchical equation of motion method has become one of the most popular numerical methods for describing the dissipative dynamics of open quantum systems linearly coupled to environment. However, its applications to systems with strong electron correlation are largely restrained by the computational cost, which is mainly caused by the high truncation tier \begin{document}$ L $\end{document} required to accurately characterize the strong correlation effect. In this work, we develop an adiabatic terminator by decoupling the principal dissipation mode with the fastest dissipation rate from the slower ones. The adiabatic terminator leads to substantially enhanced convergence with respect to \begin{document}$ L $\end{document} as demonstrated by the numerical tests carried out on a single impurity Anderson model. Moreover, the adiabatic terminator alleviates the numerical instability problems in the long-time dissipative dynamics.     

Fluidization and bubbling behavior of potash particles in a deep fluidized bed

Most existing models for predicting bubble size and bubble frequency have been developed for freely bubbling fluidized beds. Accurate prediction of bubbling behavior in deep fluidized beds, however, has been a challenge due to the higher degree of bubble coalescence and break up, high probability of the slugging regime, partial fluidization, and chaotic behavior in the bubbling regime. In this work, the bubbling and fluidization behavior of potash particles was investigated in a deep fluidized bed employing a twin-plane electrical capacitance tomography (ECT) system. Solid volume fraction, average bubble velocity, average bubble diameter, and bubble frequency in both bubbling and slugging regimes were measured at two different bed height ratios (H/D = 3.5 and H/D = 3.78). This work is the first to illustrate a sequential view of bubbles at different superficial gas velocities in a fluidized bed. The results show that both the bubble diameter and rising velocity increased with increasing the superficial gas velocity for the two bed heights, with larger values observed in the deeper bed compared to the shallower one. Predicted values for bubble diameter, bubble rise velocity and bubble frequency from different models are compared with the experimental data obtained from the ECT system in this work. Good agreement has been achieved between the values predicted by the previous models and the experimental data for the bubble diameter and bubble rise velocity with an average absolute deviation of 16% and 15% for the bed height of 49 cm and 13% and 8% for the bed height of 53 cm, respectively.     

具有颜色恒常性的光谱反射率重建

给定物体三刺激值,重建物体反射率在跨媒体颜色复制领域有着重要应用.常见的重建反射率算法包括基向量法、维纳估计法、加权伪逆方法等,这些方法大多都是为了建立由低维度三刺激值或者RGB向高维度光谱反射率的映射关系,以重建的反射率与原始反射率的接近程度为评价指标,并且需要光谱反射率数据进行训练.但是很多工业领域在产品设计时都需...     

Evaluating Feasibility of Human Tissue Engineered Respiratory Epithelium Construct as a Potential Model for Tracheal Mucosal Reconstruction

The normal function of the airway epithelium is vital for the host’s well-being. Conditions that might compromise the structure and functionality of the airway epithelium include congenital tracheal anomalies, infection, trauma and post-intubation injuries. Recently, the onset of COVID-19 and its complications in managing respiratory failure further intensified the need for tracheal tissue replacement. Thus far, plenty of naturally derived, synthetic or allogeneic materials have been studied for their applicability in tracheal tissue replacement. However, a reliable tracheal replacement material is missing. Therefore, this study used a tissue engineering approach for constructing tracheal tissue. Human respiratory epithelial cells (RECs) were isolated from nasal turbinate, and the cells were incorporated into a calcium chloride-polymerized human blood plasma to form a human tissue respiratory epithelial construct (HTREC). The quality of HTREC in vitro, focusing on the cellular proliferation, differentiation and distribution of the RECs, was examined using histological, gene expression and immunocytochemical analysis. Histological analysis showed a homogenous distribution of RECs within the HTREC, with increased proliferation of the residing RECs within 4 days of investigation. Gene expression analysis revealed a significant increase (p < 0.05) in gene expression level of proliferative and respiratory epithelial-specific markers Ki67 and MUC5B, respectively, within 4 days of investigation. Immunohistochemical analysis also confirmed the expression of Ki67 and MUC5AC markers in residing RECs within the HTREC. The findings show that calcium chloride-polymerized human blood plasma is a suitable material, which supports viability, proliferation and mucin secreting phenotype of RECs, and this suggests that HTREC can be a potential candidate for respiratory epithelial tissue reconstruction.     

LiMn2O4尖晶石氧化物的低指数表面结构优化及表面能的第一性原理研究

采用第一性原理密度泛函方法优化了LiMn₂O₄尖晶石结构, 构建并计算了其低指数表面性质. 结果表明, 广义梯度近似(GGA)和自旋极化广义梯度近似(GGA+U)计算的LiMn₂O₄晶体体相结构中, Mn的d轨道选取有效U值时晶格参数会变大. 但两种计算结果都没有显示出电荷有序和Jahn-Teller畸变的情况. LiMn₂O₄尖晶石结构缺Li条件下, (001)、(010)和(100)表面Li终端与其他终端相比表面能更低; (110)表面Mn/O终端表面能较Li/Mn/O终端更低. 在所涉及的低指数表面中(111)表面能最低, 表面重构后(111)表面能低至0.270 J/m², 是尖晶石结构中最稳定的切面. 关于反铁磁研究, (110)表面Mn/O终端表面能较Li/Mn/O终端更低. [↑↑↓↓]自旋排列下Mn/O终端表面能为1.050 J/m², [↑↓↑↓]自旋排列下Mn/O终端表面能为1.061 J/m², 即(110)-反铁磁型表面在[↑↑↓↓]自旋组态比[↑↓↑↓]的磁性顺序下更加稳定. 通过对(111)表面重构的研究, 发现该表面欠配位的锰离子会与完全配位的锂离子通过位置交换, 从而更加稳定. 重构表面的平均锰氧化态降低, 会减少Jahn-Teller效应的产生. 除(111)表面外, 其它低指数表面在铁磁和反铁磁下的表面能相似. 其中, (001)T3, (100)T1, (110)T1和(111)T2的表面结构在各自不同表面终端中具有最小的表面能. 本研究为理解LiMn₂O₄材料容量衰减问题和实验提供理论计算参考, 有助于推动高性能锂电池材料的研究.     

HL-2A等离子体边界识别的模拟研究

采用电流丝模型对HL-2A等离子体边界重建做了模拟计算。结果表明,对于孔栏位形、双零位形和下单零位形,重建的等离子体边界与平衡计算的边界能很好地吻合,最大径向距离小于8mm。     

数字滤波法再现电子全息图

在分析电子全息图特性的基础上，提出频谱滤波法对电子全息图进行数字再现，以解决其再像之间相互重叠的问题，此方法首先将数字化的电子全息图进行傅里叶变换得到全息图的空间频谱，然后对此频谱进行滤波处理并作反傅里叶变换得到一幅新的全息图，最后再用一般的数字再现法对此新的全息图进行再现，用这种方法，可以很方便地得到不受干扰的再现实像。     

推广的二进小波与信号处理

本文给出二进小波的推广,并讨了在信号处理中的应用.     

一种基于深度学习的超声导波缺陷重构方法

超声导波检测因其传播效率高、耗能少等优势成为了无损检测领域的重要研究方向.目前已有的利用超声导波进行结构缺陷探测和定量化重构的方法主要由相关的导波散射理论推导得出.然而,由于导波散射问题本身的高复杂性,使得在推导上述理论方法时引入一些近似假设,降低了重构结果的质量.另外,有些方法通过优化迭代的方式提高重构精度,又会增加...     

光谱体层析技术诊断三维等离子体场

提出一种光谱体层析图像重建新算法.通过计算机数值模拟, 考察了该算法对非对称单峰发射系数场分布的重建效果,并与传统的三维重建算法进行比对.结果表明,该算法具有收敛快,重建准确度高的特点,仅用两个方向的投影数据就能高准确度地重建单峰三维发射系数场分布.作为一个应用实例, 结合谱线相对强度测量方法重建了自由电弧等离子体的三维温度场分布.