Experimental investigation of evaporative cooling mixture of bosonic 87Rb and fermionic 40K atoms with microwave and radio frequency radiation

We investigate sympathetic cooling fermions ⁴⁰K by evaporatively cooling bosonic ⁸⁷Rb atoms in a magnetic trap with microwave and radio frequency induced evaporations in detail. The mixture of bosonic and fermionic atoms is prepared in their polarized spin states |F=9/2, m_F=9/2> for ⁴⁰K and |F=2, m_F=2> for ⁸⁷Rb, which is trapped in Quadrupole--Ioffe--Configuration trap. Comparing microwave with radio frequency evaporatively cooling bosonic ⁸⁷Rb atoms with sympathetically cooling Fermi gas ⁴⁰K, we find that the presence of rubidium atoms in the |2,1> Zeeman states, which are generated in the evaporative process, gives rise to a significant loss of ⁴⁰K due to inelastic collisions. Thus, the rubidium atoms populated in the |2, 1> Zeeman states should be removed in order to effectively perform sympathetically cooling ⁴⁰K with the evaporatively cooled ⁸⁷Rb atoms.     

弹性约束估计的显著性检验及其渐近分布

本文基于高维稀疏线性模型,研究弹性约束估计(elastic net, EN)的相关显著性检验问题,在弹性约束估计的解路径上建立Cov-EN检验.为了获取该检验的理论结果,本文回顾KKT (KarushKuhn-Tucker)条件,通过Lars算法计算得到弹性约束估计的解路径上每个节点的解析表达式,证明该检验在一般数据下渐近收敛于参数为1的指数分布.本文的数值模拟和实证分析进一步阐述Cov-EN检验的特点与作用,并与Lasso的协方差检验进行比较.     

凹凸棒土基纳米控失毒死蜱的制备及其应用

为提高农药利用率，减少农药流失，降低农药对环境的危害，研究一种以凹凸棒土（Attapulgite， ATP）为载体、毒死蜱（Chlorpyrifos， CPF）为目标农药分子制备能够减少农药流失的纳米控失毒死蜱（Nano Loss Control Chlorpyrifos， NLCC），并通过滤纸和甘蔗叶片研究ATP对CPF的控失效果，利用扫描电子显微镜（SEM）、傅里叶变换红外光谱（FT-IR）和X射线衍射仪（XRD）等表征手段研究了纳米控失毒死蜱的附着机理。最后，通过大田试验探究其实际防治效果。结果表明，凹凸棒土能够通过氢键作用吸附毒死蜱，且凹凸棒土对毒死蜱的附着量在模拟降水前后分别提高5.4和5.6 μg； 凹凸棒土对毒死蜱的最大负载量为500 mg/g； 玉米螟死亡率在模拟降水前后分别提高了20%；在大田实验中施用NLCC的甘蔗虫株率降低了21%，虫节率降低了4.3%，虫眼数减少了2个/株，株高增加了23.1 cm，也表明纳米控失毒死蜱能够有效降低虫害并在一定程度上促进甘蔗生长。这种能够减少农药流失、提高农药利用率、降低环境污染的简单且具有广泛应用前景的方法，对病虫害防治和绿色农业发展有较好的实用价值。     

Mach–Zehnder interferometer with squeezed and EPR entangled optical fields

We study a scheme for Mach-Zehnder(MZ) interferometer as a quantum linear device by injecting two-mode squeezed input states into two ports of interferometer.Two-mode squeezed states can be changed into two types of inputs for MZ interferometer:two squeezed states and Einstein-Podolsky-Rosen(EPR) entangled states.The interference patterns of the MZ interferometer vary periodically as the relative phase of the two arms of the interferometer is scanned,and are measured by the balanced homodyne detection system.Our experiments show that there are different interference patterns and periodicity of the output quantum states for two cases which depend on the relative phase of input optical fields.Since MZ interferometer can be used to realize some quantum operations,this work will have the important applications in quantum information and metrology.     

PMMA低温表面液滴凝结过程的实验研究

为了解不同温度下有机玻璃(PMMA)表面蒸汽凝结相变、液滴生长以及传热的过程,对有机玻璃表面的液滴冷凝过程进行了可视化实验观测,将液滴的凝结形态、面积率、接触角及尺寸变化等参数进行了分析并绘制出变化曲线,发现蒸汽在有机玻璃表面凝结时可形成颗粒分明的珠状液滴,凝结时间越长液滴直径越大;底板温度越低,面积率越大,接触角越大。控制以上变量可以有效改善蒸汽凝结效果,有利于提高热量传递效率,为液滴相变(汽-液)特性和换热表面结霜除霜技术提供理论支持。     

黄芩苷与铝离子配合物的电喷雾质谱研究

利用电喷雾多级串联质谱(ESI-MS^n)研究了黄芩苷与铝离子在不同浓度配比时形成的络合物,并通过质谱碎裂规律对其结构进行了初步确认。研究结果表明,黄芩苷与铝离子主要形成比较稳定的1：1和1：2配合物,分别为[AIR^1R^2L]^ 和[AlL2]^ ,其中L=[M-H]^-,R^1=CH3OH,R^2=CH3O。     

睡眠呼吸暂停综合征的生物力学研究进展

睡眠呼吸暂停综合征是一种在睡眠时反复出现咽部塌陷,引起呼吸暂停的疾病.随着该病发病率的上升及人们对生活质量及健康水平要求的提高,该疾病已经引起越来越多各学科研究人员的重视.该文简要介绍了睡眠呼吸暂停的定义、危害及诊断标准;然后从神经调控机制和生理解剖结构因素两个大的方面,介绍了诱发睡眠呼吸暂停的各种因素; 接着结合医学背景知识,从力学角度提出了引起上气道塌陷和阻止塌陷的控制机制;最后介绍了睡眠呼吸暂停生物力学研究的两种典型模型,即分布参数模型和集中参数模型,并对模型的特点及需要改进之处进行了分析和讨论.      

相位敏感光时域反射系统的时钟同源I/Q解调方法

提出一种基于时钟同源I/Q解调的相位敏感光时域反射系统解调方法.分析了调制信号与混频信号非同源不一致对解调结果的影响,采用声光调制器调制信号、斩波信号与I/Q混频信号时钟同源的方法以消除残余频率的影响.实验采用双压电陶瓷作为扰动源,通过I/Q解调实时获得后向瑞利散射光幅值和相位,进而实现扰动的定位和还原.实验结果表明,该系统能有效地探测到5km和9km处的正弦扰动,定位信号信噪比分别达17.8dB和16dB,相位解调结果准确还原正弦扰动,与正弦曲线的拟合系数分别为0.994和0.991,均方根误差分别为0.116和0.141.实验进一步验证了该方法能够测得不同扰动幅度下的相位正弦变化曲线,并能准确得到不同扰动频率,且扰动位置处相位变化幅度与扰动强度具有良好的线性关系,线性拟合系数达0.992,均方根误差为0.499,均优于非同源解调结果.     

Influence on the Lifetime of ~(87)Rb Bose-Einstein Condensation for Far-Detuning Single-Frequency Lasers with Different Phase Noises

We study the influence of the phase noises of far detuning single frequency lasers on the lifetime of Bose-Einstein condensation(BEC)of~(87)Rb in an optical dipole trap.As a comparison,we shine a continuous-wave singlefrequency Ti:sapphire laser,an external-cavity diode laser and a phase-locked diode laser on BEC.We measure the heating and lifetime of BEC in two different hyperfine states:|F=2,m_F=2〉and|F=1,m_F=1〉.Due to the narrow linewidth and small phase noise,the continuous-wave single-frequency Ti:sapphire laser has less influence on the lifetime of~(87)Rb BEC than the external-cavity diode laser.To reduce the phase noise of the external-cavity diode laser,we use an optical phase-locked loop for the external-cavity diode laser to be locked on a Ti:sapphire laser.The lifetime of BEC is increased when applfying the phase-Jocked diode laser in contrast with the external-cavity diode laser.     

数字微镜器件(DMD)杂散光特性测试方法及装置

为了获得数字微镜器件(DMD)的真实光学特性,提出了微镜单元杂散光分布测试方法,并搭建实验装置对2×2阵列区域微镜单元的杂散光分布情况进行测试.提出了一种杂散光测试方法,并针对微镜单元尺寸小、配置方式灵活的特点,设计了汇聚光斑大小连续可调的照明系统以及可以对微镜单元清晰成像的成像系统.通过实验得到了2×2阵列区域微镜单...