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991.
给出广义电磁场矢量和并矢波动方程的格林函数积分解,在物理定律和边界条件的约束下,用并矢分析的方法证明了两解的同解性,并对自由空间并矢格林函数的对称性进行了并矢分析展开验证。结合并矢分析法求解电磁场的两个应用实例,表明并矢分析法相对于传统方法具有简捷明了的特性。 相似文献
992.
993.
Shinuk Cho Junghoon Lee Minghong Tong Jung Hwa Seo Changduk Yang 《Advanced functional materials》2011,21(10):1910-1916
As a characteristic feature of conventional conjugated polymers, it has been generally agreed that conjugated polymers exhibit either high hole transport property (p‐type) or high electron transport property (n‐type). Although ambipolar properties have been demonstrated from specially designed conjugated polymers, only a few examples have exhibited ambipolar transport properties under limited conditions. Furthermore, there is, as yet, no example with ‘equivalent’ hole and electron transport properties. We describe the realization of an equivalent ambipolar organic field‐effect transistor (FET) by using a single‐component visible–near infrared absorbing diketopyrrolopyrrole (DPP)‐benzothiadiazole (BTZ) copolymer, namely poly[3,6‐dithiene‐2‐yl‐2,5‐di(2‐decyltetradecyl)‐pyrrolo[3,4‐c]pyrrole‐1,4‐dione‐5’,5’’‐diyl‐alt‐benzo‐2,1, 3‐thiadiazol‐4,7‐diyl] ( PDTDPP‐alt‐BTZ ). PDTDPP‐alt‐BTZ shows not only ideally balanced charge carrier mobilities for both electrons (?e = 0.09 cm2V?1s?1) and holes (?h = 0.1 cm2V?1s?1) but also its inverter constructed with the combination of two identical ambipolar FETs exhibits a gain of ~35 that is much higher than usually obtained values for unipolar logic. 相似文献
994.
995.
基于光谱相位相干直接电场重建法(SPIDER)测量飞秒激光脉冲的原理,建立了BBO晶体光谱滤波作用的计算模型,数值模拟了不同参数BBO晶体的视频效率带宽,给出了对于不同宽度的待测脉冲及应选取的:BBO晶体的厚度范围,并在实验中给予验证。结果表明:对于20fs的脉冲,可采用厚度为50μm的BBO晶体;而对于50fs的脉冲,采用100μm厚的BBO晶体就已经能够满足其谱宽的要求。 相似文献
996.
Controlling the interfacial properties between the electrode and active layer in organic field‐effect transistors (OFETs) can significantly affect their contact properties, resulting in improvements in device performance. However, it is difficult to apply to top‐contact‐structured OFETs (one of the most useful device structures) because of serious damage to the organic active layer by exposing solvent. Here, a spontaneously controlled approach is explored for optimizing the interface between the top‐contacted source/drain electrode and the polymer active layer to improve the contact resistance (RC). To achieve this goal, a small amount of interface‐functionalizing species is blended with the p‐type polymer semiconductor and functionalized at the interface region at once through a thermal process. The RC values dramatically decrease after introduction of the interfacial functionalization to 15.9 kΩ cm, compared to the 113.4 kΩ cm for the pristine case. In addition, the average field‐effect mobilities of the OFET devices increase more than three times, to a maximum value of 0.25 cm2 V?1 s?1 compared to the pristine case (0.041 cm2 V?1 s?1), and the threshold voltages also converge to zero. This study overcomes all the shortcomings observed in the existing results related to controlling the interface of top‐contact OFETs by solving the discomfort of the interface optimization process. 相似文献
997.
This paper presents the design of space–time block codes (STBCs) over maximum rank distance (MRD) codes, energy‐efficient STBCs, STBCs using interleaved‐MRD codes, the use of Gaussian integers for STBCs modulation, and Gabidulin's decoding algorithm for decoding STBCs. The design fundamentals of STBCs using MRD codes are firstly put forward for different number of transmit antennas. Extension finite fields (Galois fields) are used to design these linear block codes. Afterward, a comparative study of MRD‐based STBCs with corresponding orthogonal and quasi‐orthogonal codes is also included in the paper. The simulation results show that rank codes, for any number of transmit antennas, exhibit diversity gain at full rate contrary to orthogonal codes, which give diversity gain at full rate only for two transmit antennas case. Secondly, an energy‐efficient MRD‐STBC is proposed, which outperforms orthogonal STBC at least for 2 × 1 antenna system. Thirdly, interleaved‐MRD codes are used to construct higher‐order transmit antenna systems. Using interleaved‐MRD codes further reduces the complexity (compared with normal MRD codes) of the decoding algorithm. Fourthly, the use of Gaussian integers is utilized in mapping MRD‐based STBCs to complex constellations. Furthermore, it is described how an efficient and computationally less complex Gabidulin's decoding algorithm can be exploited for decoding complex MRD‐STBCs. The decoding results have been compared against hard‐decision maximum likelihood decoding. Under this decoding scheme, MRD‐STBCs have been shown to be potential candidate for higher transmit antenna systems as the decoding complexity of Gabidulin's algorithm is far less, and its performance for decoding MRD‐STBCs is somewhat reasonable. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
998.
利用全量子理论,研究了双原子与压缩相干态光场相互作用系统的量子纠缠特性,分别讨论了相干态振幅参量、光场压缩参量和耦合系数比值对系统场熵和原子相对熵演化的影响.结果表明: 当相干态振幅参量为零或很小时,两原子间纠缠度随时间演化规律和场-原子纠缠度随时间演化规律几乎相反,场-原子间的纠缠削弱了两原子间的纠缠.随着相干态振幅参量增大或光场压缩参量减小,在一定时域内,两原子处于稳定的纠缠态,并且这个时域逐渐变长,同时原子-原子平均纠缠度值增大,而场-原子平均纠缠度值减小.耦合系数比值(原子之间偶极-偶极相互作用)的增大会减弱原子与场之间的作用,使两原子始终处于最大纠缠态. 相似文献
999.
1000.