盲均衡技术的研究及发展

盲均衡技术是一种新兴的均衡技术,不需要发送训练序列就能在接收端恢复出发送序列。本文着重介绍了盲均衡技术的原理及其算法,并对盲均衡技术的新研究进行了展望。盲均衡技术能有效地克服码间干扰,对于提高通信质量具有十分重要的意义。     

Cavity-Enhanced IR Absorption in Planar Chalcogenide Glass Microdisk Resonators: Experiment and Analysis

Planar microdisk optical resonators fabricated from Ge₂₃Sb₇S₇₀ chalcogenide glass on a silicon substrate are applied for cavity-enhanced spectroscopic measurement of chemical molecular absorption fingerprint. A 0.02 cm^{- 1} detection limit for these devices is demonstrated. This detection limit represents a threefold improvement as compared to a straight waveguide sensor, while the physical device length is reduced by 40-fold. The reduction in device footprint with enhanced sensitivity makes the structure attractive for ldquosensor-on-a-chiprdquo device applications. We also present a design optimization approach for cavity-enhanced IR absorption spectroscopy using traveling-wave resonators, which indicates that further performance improvement can be achieved in optimally coupled, low-loss resonant cavities.     

Solvothermal Synthesis of High‐Quality All‐Inorganic Cesium Lead Halide Perovskite Nanocrystals: From Nanocube to Ultrathin Nanowire

Recently, all‐inorganic cesium lead halide (CsPbX₃, X = Cl, Br, I) perovskite nanocrystals have drawn much attention because of their outstanding photophysical properties and potential applications. In this work, a simple and efficient solvothermal approach to prepare CsPbX₃ nanocrystals with tunable and bright photoluminescent (PL) properties, controllable composition, and morphology is presented. CsPbX₃ nanocubes are successfully prepared with bright emission high PL quantum yield up to 80% covering the full visible range and narrow emission line widths (from 12 to 36 nm). More importantly, ultrathin CsPbX₃ (X = Cl/Br, Br, and Br/I) nanowires (with diameter as small as ≈2.6 nm) can be prepared in a very high morphological yield (almost 100%). A strong quantum confinement effect is observed in the ultrathin nanowires, in which both the absorption and emission peaks shift to shorter wavelength range compared to their bulk bandgap. The reaction parameters, such as temperature and precursors, are varied to investigate the growth process. A white light‐emitting device prototype device with wide color gamut covering up to 120% of the National Television System Committee standard has been demonstrated by using CsPbBr₃ nanocrystals as the green light source. The method in this study provides a simple and efficient way to prepare high‐quality CsPbX₃ nanocrystals.     

Metastable Copper‐Phthalocyanine Single‐Crystal Nanowires and Their Use in Fabricating High‐Performance Field‐Effect Transistors

This paper describes a simple, vapor‐phase route for the synthesis of metastable α‐phase copper‐phthalocyanine (CuPc) single‐crystal nanowires through control of the growth temperature. The influence of the growth temperature on the crystal structures, morphology, and size of the CuPc nanostructures is explored using X‐ray diffraction (XRD), optical absorption, and transmission electron microscopy (TEM). α‐CuPc nanowires are successfully incorporated as active semiconductors in field‐effect transistors (FETs). Single nanowire devices exhibit carrier mobilities and current on/off ratios as high as 0.4 cm² V^?1 s^?1 and >10⁴, respectively.     

用MOCVD方法在GaAs衬底上低温生长ZnO薄膜

采用二乙基锌(DEZn)和水(H2O)作为生长源,利用金属有机化学气相沉积(MOCVD)的方法,在100～400℃低温范围内,在GaAs(001)衬底上制备了ZnO薄膜.利用X射线衍射(XRD),室温PL,AFM,SEM研究了薄膜的晶体结构特性、发光特性及表面形貌特性.XRD分析表明ZnO薄膜具有很强的c轴取向,(002)峰的FWHM平均值为0.3°.当生长温度达到400℃时从SEM测量结果可以观察到薄膜表面呈六角状结晶.随着生长温度的升高,薄膜的晶粒尺寸变大,结晶质量得到提高但同时表面变粗糙.室温PL测量显示薄膜在370nm附近有强的近带边发射,没有观测到深能级发射峰.     

ZnO纳米棒的低温制备及表征

以硝酸锌、氨水为原料,采用低温水浴法在不同的温度下大规模制备了团簇状ZnO纳米棒,采用扫描电子显微镜(SEM)、能谱分析(EDX)、X射线衍射(XRD)、室温光致发光(PL)等手段对ZnO纳米棒进行了表征.SEM结果表明,环境温度对ZnO的形貌和性质有很大的影响,随着温度增加,ZnO长径比越来越大,当温度为90℃时ZnO的平均直径100 nm,长度约为5 μm;EDX和XRD图谱表明,ZnO纳米棒是高纯的六角纤锌矿结构;对90℃条件下制备的ZnO进行光致发光性能测试,观察到波长位于423 nm附近有较强的蓝光发射.     

无人机管线巡检中的测试桩识别

在无人机GPS信号丢失的情况下,测试桩的视觉辅助识别精度是影响油气管线自动巡检工作的关键因素。针对测试桩自动识别的精度问题,在分析测试桩及其周围地物背景目标特性的基础上,先用深度学习算法判断出测试桩被周围地物背景遮挡的情况。对于被遮挡的测试桩,采用不显著目标相对定位算法检测出测试桩的具体位置。最后通过现场采集的数据实验验证了文中算法的有效性。     

激光超声技术及其在无损检测中的应用

系统介绍了激光超声技术的研究情况,就其激发原理和检测技术作了全面的回顾与展望。综述了激光超声技术在高精度缺陷检测、高速材料表面扫描成像和恶劣环境中的检测应用。     

日本4G技术的发展动态

为了能够抢占未来移动电话技术的先机．日本政府从2001年开始就关注4G（第四代移动通信）的拄术研发和标准制订,并意图使其成为全球的标准。     

Motion differential set partition coding for image sequence and video compression

Efficient image sequence coding exploits both intra- and inter-frame correlations. Set partition coding (SPC) is efficient in intra-frame de-correlation for still images. Based on SPC, a novel image sequence coding system, called motion differential SPC (M-D-SPC), is presented in this paper. It removes inter-frame redundancy by re-using the significance map of a previously SPC coded frame. Every frame is encoded and decoded separate from other frames. Furthermore, there is no reconstruction of encoded frames in the encoder, as is done with interframe prediction methods. The M-D-SPC exhibits an auxiliary key frame coding framework, which achieves higher coding efficiency compared to the all-intra-coding schemes and meanwhile maintains the beneficial features of SPC all-intra-coding, such as computational simplicity, rate scalability, error non-propagation, and random frame access. SPIHT-based simulations on hyperspectral images, 3D/4D medical images, and video show greater compression efficiency than the standard intraframe coding method of motion JPEG2000.