医用物理学课程翻转课堂的教学改革与实践

在2018级临床医学专业医用物理学课程中进行翻转课堂试点教学,对学生考试成绩进行了统计与分析,在学时减半的情况下,进行翻转课堂教学班级的平均分略高于传统教学班级的平均分.翻转课堂为先进的教学方法,主要培养学生自主学习能力,调动学生学习的积极性,可以大范围推广使用.     

改变激发环境调控Ho3+离子的上转换发光特性

稀土掺杂上转换发光材料的发光特性不仅依赖于基质材料本身,而且与其激发条件密切相关.本文主要是以Ho^3+离子为研究对象,在NaYF4和LiYF4这两种不同的基质中,研究其在不同激发条件下的上转换发光特性.通过共聚焦显微光谱测试系统,对比Ho^3+离子在NaYF4和LiYF4微米晶体中的发光特性.实验结果发现:Ho^3+离子在这两种不同基质中均展现出较强的荧光发射.然而,当激发功率增加时,在单颗粒个LiYF4微米晶体中,当激发功率增加时,Ho^3+离子则发射出较强绿光及微弱的红光,红绿比变化并不明显,其蓝光发射强度也相对较弱.当激发这两种微米粉末晶体时,结果发现:Ho^3+离子均发射较强的绿光发射并伴有微弱红光发射,两种晶体中的发射特性极其相似.由此可见,在常规测试条件下,一些特殊发光现象是很难被观测到的.同时,通过对其光谱特性的分析,对Ho^3+离子的发光机理进行了研究.     

相对性区域创新指数与经济周期挖掘

提出了一类新的相对性区域创新指数,并采用世界专利申请数据对其进行了具体计算.基于区域创新同经济发展水平之间的超线性关系,该指数消除了经济发展水平对创新能力的影响,可以实现对不同发展水平的经济体之间进行有效的创新能力横纵对比.该创新指数尽管极其简单,却揭示出一系列迥异于传统认知的现象,例如中国大陆地区的技术创新能力在1980年代就已经位居世界前列.采用该指数,不但可以在较高水平上解释世界各国的经济增长,还发现它同经济增长率之间的相关性存在一个20年的经济周期.这些结果显示,该指数作为一个单一性指标,以极小的数据依赖就实现了较高程度的解释性,不但重新定位了世界各经济体的创新能力,对深入理解创新同经济发展之间的关系提供了新的角度,而且暗示着这类相对性经济指标的发展潜力与应用空间.     

具有高隔离度的双陷波超宽带多入多出天线

提出了一款具有高隔离度的双陷波超宽带多入多出(UWB MIMO)天线。该天线由两个相同的半切超宽带天线单元倒置构成。通过在天线底板刻蚀栅栏型缺陷地解耦结构,使该MIMO天线的隔离度提高至25 dB。此外,在天线半圆形辐射贴片上刻蚀两个方向相反的"L"型缝隙,实现了双陷波的功能,分别抑制了802.16无线城域网WiMAX(3.2~3.7 GHz)和WLAN(5.15~5.85 GHz)信号对天线系统的干扰。实验结果表明,该天线在3~11 GHz工作带宽内的隔离度大于25 dB,包络相关系数(ECC)小于0.004;第一个陷波频段为3.0~3.7 GHz,第二个陷波频段为5.1~5.85 GHz,有效抑制了WiMAX和WLAN的信号干扰。     

真空条件下LiCl溶液蒸发量随浓度变化规律研究

除湿溶液再生是除湿空调系统的核心过程,为了提高除湿溶液再生效率,以蒸发量作为评价标准,在不同的真空度下对不同浓度LiCl溶液进行再生。对不同再生条件下,溶液的再生情况进行数学模拟及实验研究,并将模拟结果与实验结果进行对比分析,结果表明,实验结果同模拟结果具有相同的变化趋势。在6 kPa和8 kPa的压强下,LiCl溶液的蒸发量随浓度的增大先上升后下降,而在1 kPa的压强下,LiCl溶液的蒸发量随浓度的增大呈现出先下降再升高接着又下降的趋势。     

Primary and subharmonic simultaneous resonance of fractional-order Duffing oscillator

Nonlinear Dynamics - The primary and subharmonic simultaneous resonance of Duffing oscillator with fractional-order derivative is studied. Firstly, the approximately analytical solution of the...     

螺栓松动边界下纤维增强复合薄板的振动测试方法

提出了基于预埋压力传感器的量化测试方法,研究了螺栓松动边界对纤维增强复合薄板振动特性的影响。首先,自主设计并开发了带有预埋压力传感器的螺栓松动边界下复合薄板的振动测试系统,并详细介绍了系统各个部件的组成和功能;然后,归纳出一套合理、规范的松动边界下复合薄板的振动测试流程,并对HF10碳纤维/树脂复合薄板进行了实际测试。结果表明:随着螺栓松动程度的不断增加,复合薄板的固有频率逐渐降低,模态振型的节线位置也发生了不同程度的变化,但其阻尼结果呈现先增大后减小的趋势;而共振和非共振响应呈现先减小后增大的趋势。     

Highly efficient perovskite solar cells by tuning electronic structures of thienothiophene-based as hole transport materials

The atomic substitutions were used to study the hole transport materials (HTM) properties of six thiophenothiophene molecules (HTM1-HTM6) to reveal the relationship between their core structures and photoelectric properties. To better investigate the difference between experimentally original and designed molecules, we calculated the hole mobility and some parameters (such as energy levels, stability, and optical properties, etc). The results showed that the molecular orbital levels of the original and designed molecules have well matched with perovskite and Ag electrode to ensure hole transport and inhibit the electron reflux. Among the designed HTMs, HTM5 has the smallest energy gap that results in the red-shifted absorption spectra. Furthermore, there is an obviously increased charge transfer integral V due to the introduction of the Si atom, which greatly improved the hole mobility. Therefore, atom substitution by introducing Si atoms (HTM5) will improve the energy levels and charge transport ability, and molecular design by means of atom substitution can be a potential way to tunable HTM performance in solar cells.     

First-principles prediction of crystal structure and physical properties of ScB3

The crystal structure of ScB₃ is seeked by combining the developed particle swarm optimisation algorithm for crystal structure prediction with first-principles calculations. A new monoclinic phase with the C2/m symmetry is predicted successfully, which is energetically more superior to the early reported R-3m-, P2₁/m-, P6₃/mmc-, P-6m2-, Pnma-, and Pm-3m-type structures in the pressure range from 0 to 100?GPa. The obtained elastic constants and phonon dispersion curve reveal that the C2/m-ScB₃ is mechanically and dynamically stable. The predicted large bulk module, high shear modulus, small Poisson’s ratio as well as the considerable hardness indicate that the C2/m-ScB₃ has outstanding mechanical property. Meanwhile, the dependences of the bulk modulus and Young’s modulus of ScB₃ on the crystal orientation are investigated theoretically. Through applying the strain–stress method, the ideal tensile and shear strengths along different crystal directions are also estimated, and the obtained results confirm that the shear mode dominates the failure mode in the C2/m-ScB₃ structure and it is intrinsically a hard material. The electronic structure calculation and chemical bonding analysis illustrate that the strong covalent B-B and Sc-B bonds are responsible for its structural stability and high hardness.     

Complementarity between micro-micro and micro-macro entanglement in a Bose–Einstein condensate with two Rydberg impurities

We theoretically study complementarity between micro-micro and micro-macro entanglement in a Bose–Einstein condensate with two Rydberg impurities. We investigate quantum dynamics of micro-micro and micro-macro entanglement in the micro-macro system. It is found that strong micro-macro entanglement between Rydberg impurities and the BEC can be generated by the use of initial micro-micro entanglement between two Rydberg impurities, which acts as the seed entanglement to create micro-macro entanglement. We demonstrate a curious complementarity relation between micro-micro and micro-macro entanglement, and find that the complementarity property can be sustained to some extent even though in the presence of the BEC decoherence.