Enhanced charge generation in doped organic/organic p–n heterojunction for improving the performance of tandem organic light emitting diode

The doped organic/organic p–n heterojunctions have been applied as charge generation structure (CGS) in tandem organic light emitting diodes (TOLEDs). It is found that the field‐induced charge generation takes place more efficiently at the interface between Li₂CO₃ n‐doped bathocuproine (BCP:Li₂CO₃) and MoO₃ p‐doped 4,4′‐N ,N′‐dicarbazole‐biphenyl (CBP:MoO₃) than at the interface between BCP:Li₂CO₃ and MoO₃ p‐doped 4,4‐bis[N‐1‐naphthyl‐N‐phenylamino]biphenyl (NPB:MoO₃). It is because the process of electrons tunneling through the depletion zone from the highest occupied molecular orbit (HOMO) of CBP:MoO₃ to the lowest unoccupied molecular orbit (LUMO) of BCP:Li₂CO₃ is more efficient than that from the HOMO of NPB:MoO₃ to the LUMO of BCP:Li₂CO₃. Compared to the TOLED using the conventional CGS of 10‐nm BCP:Li₂CO₃/20‐nm NPB:MoO₃, the one using the CGS of 10‐nm BCP:Li₂CO₃/10‐nm CBP:MoO₃/10‐nm NPB:MoO₃ shows increased device performance. In addition, the interconnecting property of CGS of 10‐nm BCP:Li₂CO₃/x nm CBP:MoO₃/20 ? x nm NPB:MoO₃ shows a strong dependence on the thickness of CBP:MoO₃. We provide a new insight on optimizing Ohmic loss in the CGSs, useful for improving the performance of TOLEDs.     

Thin‐slot formalism for the split‐field FDTD analysis of periodic structure

An expression of the thin‐slot formalism is presented to alleviate the gridding of the split‐field finite‐difference time‐domain (FDTD) solution for periodic structure. The varying auxiliary‐field ( , ) and split‐field ( , ) distributions near the slots are analytically derived from the varying field ( , ). The update equations for the split‐field FDTD are obtained by incorporating those varying field distributions into the split‐field equations in integral form. A frequency selective surface (FSS) structure is applied to verify the proposed method. The results indicate that the computational efficiency is improved.     

On Chaotic Neural Network Design: A New Framework

The theory of chaos and chaotic neural networks (CNNs) has been widely investigated in the past two decades. However, most researchers in this area have merely focused on how to make full use of CNNs to solve various problems in areas such as pattern recognition, classification, associate memory and cryptography. The philosophy of how to design a CNN is seldom discussed. In this paper, we present a general methodology for designing CNNs. By appropriately choosing a self-feedback mechanism, and also including coupling functions and an external stimulus, we have succeeded in proving that a dynamical system, defined by discrete time feedback equations, does, indeed, possess interesting chaotic properties. To the best of our knowledge, the results presented here are novel and pioneering.     

End‐Point Regulation and Vibration Suppression of a Flexible Robotic Manipulator

In this paper, end‐point regulation and vibration suppression are investigated for a flexible robotic manipulator subject to the external disturbances. The dynamics of the flexible robotic manipulator is represented by one partial differential equation (PDE) and five ordinary differential equations (ODEs). Based on the Lyapunov's direct method, boundary control is developed to drive the manipulator to the desired set‐point and simultaneously suppress the vibrations of the flexible manipulator. Considering the unknown spatiotemporally varying disturbance, uniform boundedness of the closed‐loop system is achieved. The control performance of the closed‐loop system is guaranteed by suitably choosing the design parameters. Simulations are provided to illustrate the effectiveness of the proposed control.     

Decentralized iterative learning control for large-scale interconnected linear systems with fixed initial shifts

This paper deals with the problem of iterative learning control for large-scale interconnected linear systems in the presence of fixed initial shifts. According to the characteristics of the systems, iterative learning control laws are proposed for such large-scale interconnected linear systems based on the PD-type learning schemes. The proposed controller of each subsystem only relies on local output variables without any information exchanges with other subsystems. Using the contraction mapping method, we show that the schemes can guarantee the output of the system converges uniformly to the corresponding output limiting trajectory over the whole time interval along the iteration axis. Simulation examples illustrate the effectiveness of the proposed method.     

遗传算法在跨超声速风洞总压控制中的应用

总压作为风洞控制中的重要流场参数,其调节性能是风洞控制系统能否满足试验要求的重要指标,为提高跨超声速风洞的总压控制水平,需对总压控制策略进行设计。针对某跨超声速风洞对总压控制系统提出的快速性和精确性要求,提出串级控制、智能PID控制和总压分段控制等方法,并利用MATLAB系统辨识工具箱对流场调节阶段的总压系统模型进行了辨识。提出将遗传算法应用于风洞流场调节阶段的PID控制器参数整定中,重点对基于遗传算法的PID控制原理和参数整定步骤进行介绍,并针对遗传算法的遗传算子进行了设计。系统仿真和风洞实际运行情况表明：该方法较常规PID参数整定与优化方法,具有更好的控制性能指标,满足总压控制系统精确性、快速性、鲁棒性等要求,为后续风洞建设和设备改造提供了新方法。     

大气层外弹道目标温度变化研究

针对弹道目标在飞行过程中的表面温度是导弹攻防两端关注的重点,简要介绍了弹道目标在大气层外飞行时的表面温度及红外辐射源;提出了大气层外弹道目标在飞行过程中的表面温度计算方法;重点针对弹头与诱饵的典型热物参数和大气层外不同的表面初始温度,分别计算了在阴影区与日照区弹头和诱饵表面温度随飞行时间的变化情况,发现弹头热惯量大,基本保持初始温度,诱饵热惯量小,迅速就会达到平衡温度,并采用实例对其进行验证。     

基于抽样理论的改进型星座覆盖分析方法

针对传统网格点方法在分析星座对目标区域的覆盖性能时,存在着计算效率不高的问题,利用抽样理论中借助样本统计量对总体参数进行估计的思想,对传统网格点方法加以了改进;通过分析星座对目标区域内所有网格点的覆盖情况与网格点经纬度之间的关系,确立了对所有网格点构成的总体采用先分层后随机的抽样方式,并分析了层的划分和样本量在各层的分配;根据不同指标的统计特征,给出了不同星座覆盖性能指标的估计方法和不同精度条件下总样本量的计算过程,并建立了改进网格点法的实施流程;最后利用改进方法计算了仿真时段内北斗卫星导航系统对某一地面区域的平均PDOP值,通过与传统网格点方法的仿真结果进行比较并对仿真数据进行分析,证明了该改进方法在保证计算精度的同时,有效地提升了计算效率。