介绍了一种在多个相互正交的子载波上并行传输数据的技术——正交频分复用(OFDM:Orthogonal Frequency Division Multiples)技术,主要研究与探讨了基带OFDM调制解调技术的基本原理及其关键技术。讨论了调制解调中的星座映射,然后在计算...介绍了一种在多个相互正交的子载波上并行传输数据的技术——正交频分复用(OFDM:Orthogonal Frequency Division Multiples)技术,主要研究与探讨了基带OFDM调制解调技术的基本原理及其关键技术。讨论了调制解调中的星座映射,然后在计算机上用Matlab软件对OFDM系统中常使用的QAM,QPSK和BPSK调制进行仿真,分别对各个调制方式的误码率性能进行讨论,并给出仿真结果,最后分析了基4按频率抽取的FFT算法及OFDM的FFT实现。展开更多
通过射频磁控溅射法和脉冲激光沉积法,以Ti-Al为阻挡层,在(001)Si衬底上制备了La0.5Sr0.5CoO_3(LSCO)/Na_(0.5)Bi_(0.5)TiO_3(NBT)/LSCO(LSCO/NBT/LSCO)异质结铁电电容器。研究了Na_(0.5)Bi_(0.5)TiO_3铁电薄膜的结构和物理性能。结果表...通过射频磁控溅射法和脉冲激光沉积法,以Ti-Al为阻挡层,在(001)Si衬底上制备了La0.5Sr0.5CoO_3(LSCO)/Na_(0.5)Bi_(0.5)TiO_3(NBT)/LSCO(LSCO/NBT/LSCO)异质结铁电电容器。研究了Na_(0.5)Bi_(0.5)TiO_3铁电薄膜的结构和物理性能。结果表明:Ti-Al阻挡层为非晶结构,NBT薄膜结晶质量良好。在1 500 k V/cm驱动电场下,LSCO/NBT/LSCO电容器呈现饱和的电滞回线,具有较大的剩余极化强度(47.9μC/cm2)和较小的脉宽依赖性,而且抗疲劳特性和保持特性良好。此外,漏电机制研究表明:当外加电场小于400 k V/cm时,LSCO/NBT/LSCO电容器满足欧姆导电机制,在电场大于400 k V/cm时,满足空间电荷限流传导机制。展开更多
Particle motion in confined shear flow of viscoelastic fluids is very common in nature and has a wide range of applications.Understanding and mastering the motion characteristics of particles in viscoelastic fluids ha...Particle motion in confined shear flow of viscoelastic fluids is very common in nature and has a wide range of applications.Understanding and mastering the motion characteristics of particles in viscoelastic fluids has important academic value and practical significance.In this paper,we first introduce the related equations and characteristic parameter,and then emphasize the following issues:the lateral equilibrium position of particle;interaction and aggregation of multiple particles;the chain structure formed by multiple particles;and the motion of non-spherical particle.Finally,some unresolved issues,challenges,and future research directions are highlighted.展开更多
文摘介绍了一种在多个相互正交的子载波上并行传输数据的技术——正交频分复用(OFDM:Orthogonal Frequency Division Multiples)技术,主要研究与探讨了基带OFDM调制解调技术的基本原理及其关键技术。讨论了调制解调中的星座映射,然后在计算机上用Matlab软件对OFDM系统中常使用的QAM,QPSK和BPSK调制进行仿真,分别对各个调制方式的误码率性能进行讨论,并给出仿真结果,最后分析了基4按频率抽取的FFT算法及OFDM的FFT实现。
文摘通过射频磁控溅射法和脉冲激光沉积法,以Ti-Al为阻挡层,在(001)Si衬底上制备了La0.5Sr0.5CoO_3(LSCO)/Na_(0.5)Bi_(0.5)TiO_3(NBT)/LSCO(LSCO/NBT/LSCO)异质结铁电电容器。研究了Na_(0.5)Bi_(0.5)TiO_3铁电薄膜的结构和物理性能。结果表明:Ti-Al阻挡层为非晶结构,NBT薄膜结晶质量良好。在1 500 k V/cm驱动电场下,LSCO/NBT/LSCO电容器呈现饱和的电滞回线,具有较大的剩余极化强度(47.9μC/cm2)和较小的脉宽依赖性,而且抗疲劳特性和保持特性良好。此外,漏电机制研究表明:当外加电场小于400 k V/cm时,LSCO/NBT/LSCO电容器满足欧姆导电机制,在电场大于400 k V/cm时,满足空间电荷限流传导机制。
基金supported by the National Natural Science Foundation of China(Grant No.11632016).
文摘Particle motion in confined shear flow of viscoelastic fluids is very common in nature and has a wide range of applications.Understanding and mastering the motion characteristics of particles in viscoelastic fluids has important academic value and practical significance.In this paper,we first introduce the related equations and characteristic parameter,and then emphasize the following issues:the lateral equilibrium position of particle;interaction and aggregation of multiple particles;the chain structure formed by multiple particles;and the motion of non-spherical particle.Finally,some unresolved issues,challenges,and future research directions are highlighted.
