Exploring the Origin of Maximum Entropy States Relevant to Resonant Modes in Modern Chladni Plates

The resonant modes generated from the modern Chladni experiment are systematically confirmed to intimately correspond to the maximum entropy states obtained from the inhomogeneous Helmholtz equation for the square and equilateral triangle plates. To investigate the origin of maximum entropy states, the inhomogeneous Helmholtz equation is modified to consider the point interaction coming from the driving oscillator. The coupling strength associated with the point interaction is characterized by a dimensionless factor α. The δ potential of the point interaction is numerically modelled by a truncated basis with an upper index N. The asymptotic behavior for the upper index N is thoroughly explored to verify that the coupling strength of α = 1.0 can make the theoretical resonant modes agree excellently with the maximum entropy states as N→∞. It is further authenticated that nearly the same resonant modes can be obtained by using a larger coupling strength α when a smaller upper index N is exploited in the calculation.     

Stability analysis for uncertain nonlinear switched systems with infinite-time domain

Fuzzy Optimization and Decision Making - In this paper, an uncertain nonlinear switched system is a nonlinear switched system disturbed by subjective uncertainties, which can be illustrated by...     

混合型间隔层对荧磷混合式白色有机电致发光器件性能的影响

制备了基于新型蓝绿色荧光MQAB与红色磷光Ir(MDQ)2acac的荧磷混合式白色有机电致发光器件,并探讨了TPBI或UGH3两种间隔层及二者的混合间隔层的器件的发光性能.研究发现,采用TPBI和UGH3的混合间隔层可以调控载流子注入与传输的平衡.当m(TPBI)∶ m(UGH3)=1∶1时,可有效地控制发光区域,使得器件性能得到优化,并获得发光亮度高达14 700 cd/m2的白色有机电致发光器件,最高电流效率可达11.60 cd/A,且器件具有较高的色稳定性.采用混合间隔层的器件比单用TPBI或UGH3作为间隔层的器件效率提高了200％ ～ 300％.     

传输交流的Bi2223/Ag高温超导带在不同取向交流外场下的交流损耗

在高温超导的电力应用中，如超导电机、变压器等，多数情况下，高温超导带材在通以交流传输电流的同时还处于交变磁场中。此时，超导体的交流损耗不仅依赖于磁场的大小，还与磁场相对于超导带面的取向有关。本文在77K及工频50Hz情况下，实验研究了单根多芯Bi2223/Ag高温超导带及两带并联时的交流损耗随着外磁场与带面夹角的变化情况；以及交流磁场对临界电流的影响情况；并对单根带及两带并联的实验结果进行了比较与分析。     

KNSBN晶体猫式互抽动相位共轭光特性

在KNSBN：Ce晶体中，利用二波耦合作用，在单一光束无法获得相位共轭光的条件下，实现了“猫”式互抽运相位共轭光输出，获得较高的共轭光发射率，实验结果表明，晶体的二波耦合作用可以使晶体的自抽运相位共轭光的阈值光强降低。入射光的入射角范围增大，响应时间缩短。     

Enhanced accuracy by post-processing for finite element methods for hyperbolic equations

We consider the enhancement of accuracy, by means of a simple post-processing technique, for finite element approximations to transient hyperbolic equations. The post-processing is a convolution with a kernel whose support has measure of order one in the case of arbitrary unstructured meshes; if the mesh is locally translation invariant, the support of the kernel is a cube whose edges are of size of the order of only. For example, when polynomials of degree are used in the discontinuous Galerkin (DG) method, and the exact solution is globally smooth, the DG method is of order in the -norm, whereas the post-processed approximation is of order ; if the exact solution is in only, in which case no order of convergence is available for the DG method, the post-processed approximation converges with order in , where is a subdomain over which the exact solution is smooth. Numerical results displaying the sharpness of the estimates are presented.

     

Eu2+,Dy3+共掺杂硼铝锶长余辉玻璃陶瓷

首次介绍了一种新型长余辉材料:Eu^2 ,Dy^3 共掺杂硼铝锶长余辉玻璃陶瓷，该玻璃陶瓷用紫外灯、日光、荧光灯均可激发，发射黄绿色余辉，余辉的发射峰位于516nm，来自于Eu^2 的5d→^8S7/2跃迁。用12000 lx的荧光灯激发样品20分钟，停止激发后10秒时，该玻璃陶瓷的余辉亮度为3．53cd/m^2，色坐标为：x=0.2842,y=0.5772;停止激发后5小时55分钟，该玻璃陶瓷的余辉亮度为0．01cd/m^2；停止激发30小时后，余辉在黑暗中仍肉眼可见。文中对该玻璃陶瓷的相关性质进行了表征，并提出了可能的长余辉机理。     

硫和银共掺杂介孔TiO2的制备、表征及其对染料的光催化降解活性

以P123为模板,以钛酸四正丁酯、硝酸银和硫脲为原料采用模板法制备了一系列硫和银共掺杂介孔TiO₂光催化材料．利用SEM、XRD、BET和紫外-可见光谱等技术对其形貌、晶体结构及表面结构、光吸收特性等进行了表征．以甲基橙溶液的光催化降解为模型反应,考察了不同掺杂量的样品在紫外和可见光下的光催化性能．结果表明,用模板法制备的共掺杂介孔TiO₂光催化材料在紫外和可见光条件下较纯介孔TiO₂和单掺杂介孔TiO₂对甲基橙溶液具有更好的光催化降解效果, 且硫和银的掺杂量及样品焙烧温度显著影响该材料的催化性能．当硫掺杂量为2mol%和银掺杂量为1mol%,在500 oC 焙烧2 h所得光催化材料的催化性能最佳,4 h即可使甲基橙的降解率达98.8%,重复使用4次仍可使甲基橙的降解率保持在87.5%以上     

谷值电流型脉冲序列控制开关变换器及其能量建模研究

脉冲序列控制是针对工作于电感电流断续导电模式的开关变换器提出的一种非线性、离散控制技术.当开关变换器工作在电感电流连续导电模式时,脉冲序列控制开关变换器存在低频振荡现象,严重影响了脉冲序列控制开关变换器的稳态及瞬态性能.针对这一问题,本文提出一种谷值电流型脉冲序列控制方法,将脉冲序列控制的应用范围从电感电流断续导电模式扩展到电感电流连续导电模式.建立了谷值电流型脉冲序列控制开关变换器的能量迭代模型,并与传统脉冲序列控制开关变换器的能量模型进行对比.结果表明谷值电流型脉冲序列控制电感电流连续导电模式开关变换器具有与传统脉冲序列控制电感电流断续导电模式开关变换器相同的能量传递模式,从而在根本上消除了传统脉冲序列控制电感电流连续导电模式变换器存在的低频振荡现象.     

Effect of incommensurate potential on the resonant tunneling through Majorana bound states on the topological superconductor chains

We study the transport through the Kitaev chain with incommensurate potentials coupled to two normal leads by the numerical operator method. We find a quantized linear conductance of e ² / h, which is independent to the disorder strength and the gate voltage in a wide range, signaling the Majorana bound states. While the incommensurate potential suppresses the current at finite voltage bias, and then narrows the linear response regime of the I-V curve which exhibits two plateaus corresponding to the superconducting gap and the band edge, respectively. The linear conductance abruptly drops to zero as the disorder strength reaches the critical value 2g _s + 2Δ with Δ the p-wave pairing amplitude and g _s the hopping between neighbor sites, corresponding to the transition from the topological superconducting phase to the Anderson localized phase. Changing the gate voltage also causes an abrupt drop of the linear conductance by driving the chain into the topologically trivial superconducting phase, whose I-V curve exhibits an exponential shape.