疫情下电磁场理论课程的网络教学

本文主要总结了新冠疫情期间作者的电磁场理论课程在线教学经验。对比分析了录播和直播的优缺点后,选择录播教学方式。基于超星网络教学平台,展示了录播网络教学的具体措施,包括网上答疑和学习效果检查以及在线批改作业等。给出了网络教学可以为线下教学继续使用的方法和手段,为疫情结束后的正常教学提供了新的网络教学补充措施。     

抑霜型空气源热泵机组应用实测研究

空气源热泵结霜过程会恶化机组的实际运行性能，重霜工况下尤为严重，发展抑霜型空气源热泵是保障其高效适用和良性发展的关键。本文依托四川省康定市的某住宅示范工程，开展抑霜型空气源热泵和常规型空气源热泵的现场实测研究，研究抑霜型空气源热泵实际应用中的抑霜、制热性能表现，并进行技术经济性分析。结果表明：抑霜型空气源热泵抑霜效果显著，制热性能得到显著改善，能效提升达到21%~37.3%，费用年值比常规空气源热泵降低了13%，1年左右即可回收追加的投资，具有更好的技术经济性，有助于空气源热泵技术在严重结霜气候区域的高效应用。     

条形药包爆破震动场的试验研究

通过时条形药包周围实测爆破震动数据采用数值计算方法进行处理，作出了条形药包周围的爆破震动场，使我们对条形药包的爆破地震效应有了全面的认识，从而在实际工程爆破中能够有针对性地进行安全防护。分析研究认为：条形药包周围的震动场由一系列同心椭圆形等震线组成。在爆破近区由于位置因素的影响，等震线的长轴与药包轴线重合；在远区的震动主要受波动干涉作用的影响，致使长轴与药包轴线垂直，因此不能采用集中药包的计算方法。     

Description of the thermodynamic properties and fluid-phase behavior of aqueous solutions of linear,branched, and cyclic amines

The SAFT-γ Mie group-contribution equation of state is used to represent the fluid-phase behavior of aqueous solutions of a variety of linear, branched, and cyclic amines. New group interactions are developed in order to model the mixtures of interest, including the like and unlike interactions between alkyl primary, secondary, and tertiary amine groups (NH₂, NH, N), cyclic secondary and tertiary amine groups (cNH, cN), and cyclic methine-amine groups (cCHNH, cCHN) with water (H₂O). The group-interaction parameters are estimated from appropriate experimental thermodynamic data for pure amines and selected mixtures. By taking advantage of the group-contribution nature of the method, one can describe the fluid-phase behavior of mixtures of molecules comprising those groups over broad ranges of temperature, pressure, and composition. A number of aqueous solutions of amines are studied including linear, branched aliphatic, and cyclic amines. Liquid–liquid equilibria (LLE) bounded by lower critical solution temperatures (LCSTs) have been reported experimentally and are reproduced here with the SAFT-γ Mie approach. The main feature of the approach is the ability not only to represent accurately the experimental data employed in the parameter estimation, but also to predict the vapor–liquid, liquid–liquid, and vapor–liquid–liquid equilibria, and LCSTs with the same set of parameters. Pure compound and binary phase diagrams of diverse types of amines and their aqueous solutions are assessed in order to demonstrate the main features of the thermodynamic and fluid-phase behavior.     

某福利院一起肠炎沙门菌食源性疾病的调查分析

目的 对某福利院一起肠炎沙门菌食源性疾病进行调查和溯源,为研究相关食源性疾病提供参考。方法采用流行病学、食品卫生学和脉冲场凝胶电泳(PFGE)同源性分析等方法,分析本次食源性疾病事件。结果 确认本次事件中病例23名,患病率5.65%(23/407)；现场采集病例肛拭子15份和厨房工作人员肛拭子3份、留样菜品3份、水果2份以及冰棒1份,其中从11份病例肛拭子中检出肠炎沙门菌,PFGE结果显示11株肠炎沙门菌的DNA条带图谱相似性为96.4%,聚类分析为同一型,结合流行病学调查,初步判断菌株来自同一克隆系。结论 综合流行病学、食品卫生学和实验室检测结果,确定为一起肠炎沙门菌引起的食源性疾病,福利院应加强对特殊人群的饮食安全管理,制定相应的食源性疾病突发事件应急处理预案,防止此类事故再发生。     

Flash joining of alumina ceramics under a small current density

The ceramic joining using electric field (E-field) has garnered significant research attention due to the decreased joining barrier and enhanced reliability. However, the underlying mechanism of E-field assisted joining remains unclear. Herein, we report the rapid joining of alumina ceramics using a small current. Moreover, the E-field is applied in both perpendicular and parallel directions to the faying surfaces, demonstrating a significant difference in terms of joint strength. These results indicate that the E-field generates defects and promotes the joining process by facilitating ionic diffusion.     

梯度铝蜂窝夹芯板的力学行为

梯度分层铝合金蜂窝板是一种有效的吸能结构,本工作在梯度铝蜂窝结构的基础上根据梯度率的概念,通过改变蜂窝芯层的胞壁长度,设计了4种质量相同、梯度率不同的铝蜂窝夹芯结构。通过准静态压缩实验,并结合非线性有限元模拟准静态及冲击态下梯度铝蜂窝夹芯结构的变形情况及其力学性能,分析对比了相同质量下梯度铝蜂窝夹芯结构在准静态下的变形模式以及冲击载荷下分层均质蜂窝结构和不同梯度率的分层梯度蜂窝结构的动态响应和能量吸收特性。结果表明:在准静态压缩过程中,铝蜂窝梯度夹芯板的变形具有明显的局部化特征,蜂窝芯的变形为低密度优先变形直至密实,层级之间的密实化应变差随芯层密度的增大而逐渐减小;在高速冲击下,梯度蜂窝板并非严格按照准静态过程中逐级变形直至密实,而是在锤头冲击惯性及芯层密度的相互作用下整体发生的线弹性变形、弹性屈曲、塑性坍塌及密实化;另外,在本工作所设计的梯度率中,当梯度率为γ₁=0.0276时,梯度蜂窝夹芯板的吸能性达到最好,相较于同等质量下的均质蜂窝夹芯板,能量吸收提高了10.63%。     

Relationship of the different Ca sites in the matrix with luminescence properties of orange‒red emitting Li0.04Ca0.96-xSiO3:Smx phosphors

Li_0.04Ca_0.96-xSiO₃:Sm_x orange?red emitting phosphors were synthesized using the sol-gel method. X-ray diffraction, Rietveld refinement of XRD patterns, Fourier transform infrared spectroscopy and ?uorescence spectrophotometry were used to characterize the crystal structure, sites of cationic Ca and luminescence properties of the prepared phosphors. The relationship of the different Ca sites in the matrix with the luminescence properties was analysed. The results indicate that the prepared phosphors reveal a β-CaSiO₃ phase with a monoclinic crystal structure and space Group P21/a. As the Sm³⁺ concentration increases, the unit cell volume of phosphors and the Ca–O band lengths of different Ca sites decrease due to substitution of Ca²⁺ by smaller Sm³⁺ ions. By excitation at 404 nm, Li_0.04Ca_0.96-xSiO₃:Sm_x phosphors exhibit warm orange?red light, corresponding to the electron transitions from ⁴G_5/2 → ⁶H_5/2 (567 nm), ⁴G_5/2 → ⁶H_7/2 (605 nm) and ⁴G_5/2 → ⁶H_9/2 (651 nm) of Sm³⁺. The concentration quenching phenomenon appears at Sm³⁺ concentrations beyond 0.02. The refinement results demonstrate that three cationic Ca sites, named Ca1, Ca2 and Ca3, exist in the β-CaSiO₃ host lattice. The Ca²⁺ ions at Ca1 and Ca2 sites are coordinated with six oxygen ions, leading to the same coordination number (CN). The Ca²⁺ ion located at Ca3 site has seven coordination numbers. The Ca1 site possesses a smaller lattice distortion and better symmetry than those of Ca2 and Ca3 sites. However, the Ca3 site exhibits the largest lattice distortion and poor symmetry. The Sm³⁺ present in symmetric Ca1 sites in the matrix illustrates the strong emission intensity, long luminescence lifetimes and good thermal stability.     

Various density light field image coding based on distortion minimization interpolation

In recent years, the light field (LF) as a new imaging modality has attracted wide interest. The large data volume of LF images poses great challenge to LF image coding, and the LF images captured by different devices show significant differences in angular domain. In this paper we propose a view prediction framework to handle LF image coding with various sampling density. All LF images are represented as view arrays. We first partition the views into reference view (RV) set and intermediate view (IV) set. The RVs are rearranged into a pseudo sequence and directly compressed by a video encoder. Other views are then predicted by the RVs. To exploit the four dimensional signal structure, we propose the linear approximation prior (LAP) to reveal the correlation among LF views and efficiently remove the LF data redundancy. Based on the LAP, a distortion minimization interpolation (DMI) method is used to predict IVs. To robustly handle the LF images with different sampling density, we propose an Iteratively Updating depth image based rendering (IU-DIBR) method to extend our DMI. Some auxiliary views are generated to cover the target region and then the DMI calculates reconstruction coefficients for the IVs. Different view partition patterns are also explored. Extensive experiments on different types LF images also valid the efficiency of the proposed method.