Deepening Insights into Aggregation Effect of Intermolecular Charge-Transfer Aggregates for Highly Efficient Near-Infrared Non-Doped Organic Light-Emitting Diodes over 780 nm

Though urgently needed, high-efficiency near-infrared (NIR) organic light-emitting diode (OLED) is still rare due to the energy-gap law. Formation of intermolecular charge-transfer aggregates (CTA) with nonadiabatic coupling suppression can decelerate non-radiative decay rates for high-efficiency NIR-OLEDs. However, the aggregation effect of CTA is still not fully understood, which limits the rational design of CTA. Herein, two CTA molecules with a same π-framework but different terminal substituents are developed to unveil the aggregation effect. In highly ordered crystalline states, the terminal substituents substantially affect the molecular packing motifs and intermolecular charge-transfer states, thus leading to distinct photophysical properties. In comparison, in amorphous states, these two CTA demonstrate similar photophysical behaviors and properties due to their similar molecular packing and intermolecular interactions as evidenced by molecular dynamics simulations. Importantly, the formations of amorphous CTA trigger multifunction improvements such as aggregation-induced NIR emission, aggregation-induced thermally activated delayed fluorescence, self-doping and self-host features. The non-doped OLEDs demonstrate NIR emissions centered at 788 and 803 nm, and high maximum external quantum efficiencies of 2.6% and 1.5% with small efficiency roll-off, respectively. This study provides deeper insight into the aggregation effect of CTA and lays a foundation for the development of high-efficiency NIR non-doped OLEDs.     

A novel out-of-band emission suppression method in future wireless communications employing filtered orthogonal frequency division multiplexing waveform

In order to achieve flexible configuration and asynchronous transmission of different subbands (SBs), SB filters are utilized in filtered orthogonal frequency division multiplexing (f-OFDM) systems to isolate different SBs efficiently. Nevertheless, the price is the insertion of some intrinsic interference.Therefore, the suppression of the out-of-band emission (OOBE) between SBs is essential for the system performance improvement of f-OFDM. According to the system structure of f-OFDM, an optimization design model based on active interference cancelation (AIC) is proposed in this study, and the optimization design model is solved through second order cone programming. Furthermore, the effectiveness of the proposed AIC algorithm in OOBE suppression is verified by computer simulations. To the whole system, the OOBE suppression also means the decrease of inter-SB interference (ITBI). In addition, the influences of main parameters, such as the number of the cancelation carriers (CCs), on the OOBE suppression performance of the proposed AIC algorithm, are simulated and analyzed. Moreover, some intrinsic characteristics of the proposed algorithm in parameter configuration are revealed in terms of power spectral density (PSD) and bit error ratio (BER).     

活塞环-缸套贫油润滑特性仿真分析

为研究柴油机在贫油润滑状态下活塞环-缸套摩擦副的润滑特性，以活塞环-缸套摩擦副为研究对象，基于平均雷诺方程和微凸体接触模型，建立活塞环-缸套摩擦副一维混合润滑模型，并在该模型的基础上，根据来流油膜厚度计算贫油状态润滑域，得到贫油润滑模型。通过贫油润滑模型，对不同载荷、不同频率、不同贫油程度对润滑油膜厚度、摩擦力、摩擦因数等参数的影响进行仿真。结果表明：在贫油润滑时油膜厚度分布规律与富油润滑时的分布规律类似，但油膜厚度与润滑区宽度均小于富油润滑；微凸体承载力占比增大，动压润滑效应被削弱，摩擦因数增大。     

超临界电站锅炉三维虚拟仿真系统开发

针对电站锅炉所涉及的设备庞大、结构复杂和工作原理抽象等问题，以HG−1120/25.8−YM3型超临界锅炉为研究对象，利用Creo建模技术建立了1∶1尺寸的锅炉实体三维模型。利用UE4虚拟仿真技术开发了一套具有高逼真性和强交互性的复杂三维虚拟仿真系统，实现了该超临界锅炉的虚拟漫游、典型锅炉结构拆解、信息展示和工作原理演示等功能，有助于进一步提升火力发电厂和特种设备检测单位相关人员的专业技能水平。另外，对虚拟仿真系统的开发流程、关键技术与环节进行了研究，可为高校热能与动力工程相关虚拟实验平台的建立提供人机交互可视化参考方案。