LIF技术与ELM算法的电力变压器故障诊断研究

电力变压器油的检测分析是电力变压器故障诊断的有效方法,快速识别电力变压器油的油样对电力变压器故障诊断工作有重大意义.常规的电力变压器油的检测技术主要是气相色谱法,此方法操作比较复杂,且不适合在线检测,不能及时发现变压器的故障隐患.提出一种激光诱导荧光光谱(L IF)技术与极限学习机(ELM)算法的电力变压器故障诊断研究...     

六角柱形NaErF_(4)和NaErF_(4)@NaYF_(4)核壳微粒制备及多色上转换荧光调控性能EI北大核心CSCD

采用简单的水热法合成了六角柱形NaErF_(4)和NaErF_(4)@NaYF_(4)核壳上转换发光材料,利用扫描电镜(SEM)、X射线粉末衍射(XRD)和荧光光谱(PL)等表征对材料的形貌、结构和上转换发光性能进行了研究。结果表明,纯NaErF_(4)样品为六角柱形,边长和厚度均为1μm左右,样品表面光滑。随着NaYF_(4)壳层的包覆,六角相NaErF_(4)周围出现了大量的立方相NaYF_(4)纳米颗粒,得到了NaErF_(4)@NaYF_(4)核壳结构。荧光光谱表明,通过在六角柱形NaErF_(4)表面包覆NaYF_(4)壳层,可以有效增强上转换发光强度,其中,位于527,543,663 nm处的3个发射峰分别对应于Er^(3+)的^(2)H_(11/2)→^(4)I_(15/2)、^(4)S_(3/2)→^(4)I_(15/2)和^(4)F_(9/2)→^(4)I1_(5/2)能级跃迁。随着壳层中Y∶F比例的增加,立方相NaYF_(4)的晶体衍射峰逐渐增强;同时,对应的NaErF_(4)@NaYF_(4)样品发射光谱中红绿比(R/G)逐渐增大,发光颜色也从绿色、经黄绿色逐渐向黄色过渡,实现了多色发光。     

盐湖卤水中微量钒的浓度测定

为了测定盐湖卤水中微量钒的浓度,开发了一个钒的分离纯化流程来降低大量的共存离子的基质效应。该分离纯化流程包括萃取和反萃两个步骤。详细地研究了影响钒纯化效率的各种因素,得到钒的最佳分离纯化条件为:以正己烷为稀释剂,有机相中D2EHPA和TBP的体积百分比分别为30%及20%,在pH为3.0时萃取30 min;然后用3 mol/L H₂SO₄反萃 10 min。基于此分离纯化流程,将两个实际盐湖卤水样品中的微量钒纯化后,再用电感耦合等离子体质谱仪(ICP-MS)测定其浓度,该ICP-MS对51V 的检测灵敏度和检测限别为53 171 cps/(μg/L) 和1.88 ng/L。所得实际盐湖卤水钒测定结果的加标回收率接近100%而相对标准偏差低于0.6%,表明该方法可用于实际复杂体系中微量钒的浓度测定,例如海水和盐湖卤水。     

ADS堆功率控制研究及其在DCS系统的实施

研究了基于加速器束流强度调节来控制中国加速器驱动嬗变研究装置(CiADS)次临界堆功率的方法.束流强度的调节是通过比较堆功率的测量值和设定值,由PID(比例-积分-微分)控制器自动控制可调光阑的孔径大小完成的.为了评估所提出的自动控制方法,基于点堆动力学方程建立了CiADS次临界堆堆芯模型.基于CiADS堆芯模型的仿真...     

激光拉曼分光计中超低杂散光的测试

本文提出了一种测试激光拉曼分光计中超低杂散光的新方法.实验结果表明,本方法的杂散光测量限可达10~(-14)量级.     

Compton散射下等离子体中电子相轨道的演化

用KMR模型研究了等离子体中多光子非线性Compton散射下电子相轨道的演化,发现电子与光子进行能量交换后,只有未被俘获电子的相轨道才能从周期性向非周期性、随机型演化,其演化剧烈程度随电子吸收光子数的增大而加剧,随电子与光子碰撞非弹性成分和碰撞前初始速度的增大而迅速减弱,但低于强激光场中的剧烈程度。当电子被光场俘获时,这种演化过程结束并做稳定的运动,光子不再为电子提供能量。     

Thermal Quantum Discord in Anisotropic Heisenberg XXZ Model withDzyaloshinskii-Moriya Interaction

The thermal quantum discord (QD) is studied in a two-qubit Heisenberg XXZ system with Dzyaloshinskii-Moriya (DM) interaction. We compare the thermal QD with thermal entanglement in this system and find remarkable differences between them. For instance, we show situations where QD decreases asymptotically to zero with temperature T while entanglement decreases to zero at the point of critical temperature, situations where QD decreases with certain tunable parameters such as D_z and D_x when entanglement increases. We find that the characteristic of QD is exotic in this system and this possibly offers a potential solution to enhance entanglement of a system. We also show that tunable parameter D_x is more efficient than parameter D_z in most regions for controlling the QD.     

Tripartition of Arbitrary Single-Qubit Information via a Class of Asymmetric Four-Qubit W State

A four-party scheme is put forward for a sender to partition arbitrary single-qubit information among three receivers by utilizing a class of asymmetric four-qubit W state as quantum channels. In the scheme the sender＇s quantum information can be recovered by the three receivers if and only if they collaborate together. Specifically, they collaborate to perform first two different 2-qubit collective unitary operations and then a single-qubit unitary operation. The scheme is symmetric and （3, 3）-threshold with regard to the reconstruction, for any receiver can be assigned to conclusively recover the quantum information with the other two＇s assistances.     

利用复合色彩转换膜实现白色有机电致发光

利用蓝色有机发光二极管激发荧光色彩转换膜的方法,制备了一种新型的白色有机电致发光器件.蓝色有机发光二极管的发光层采用在4,4′-Bis(carbazol-9-yl)biphenyl(CBP)主体中掺杂高效蓝色荧光染料N-(4-((E)-2-(6-((E)-4-(diphenylamino)styryl)naphthalen-2-yl)vinyl)phenyl)-N-phenylbenzenamine(N-BDAVBi)来制备.有机/无机复合色彩转换膜是将有机荧光颜料VQ-D25和无机荧光粉钇铝石榴石(YAG)按一定的重量比均匀分散到-[CH3CH2COOCH3]n-(PMMA)中经涂敷、固化而成.通过与单纯有机或无机色彩转换膜的比较及调整复合转换膜本身的厚度和荧光颜料的掺杂比例来优化白光器件的发光光谱,获得了色稳定性较高的白色有机电致发光器件.当驱动电压由6V升至14V时,器件的色坐标仅在(0.354,0.304)和(0.357,0.312)之间变化,其最高电流效率约为5.8cd/A(4.35mA/cm2),最高亮度为16800cd/m2(14V).     

Two Kinds of Cavity Geometry for Enhanced Laser Cooling of Solids

We present a comparison between intracavity cooling and external cavity cooling for optical refrigeration. The results show that the intracavity scheme is preferred at low optical densities （〈 0.008）, while the external cavity scheme is preferred at higher optical densities （〉 0.01）. We can choose the proper scheme for different eases in experiments. Moreover, under the same conditions, taking Yb^3＋-doped ZBLAN （ZrF4-BaF2-LaF3-AlFa-NaF） film as an example, the cooling processes of the two scheme are obtained. The calculated results show that intracavity cooling will achieve a larger temperature drop for a thin film sample. Finally, the diode laser may become a candidate for the intraeavity model briefly discussed.