Noise limit in heterodyne Interferometer demodulator for FBG-based sensors

This paper reports the results of a recent investigation on the noise-limited performance in heterodyne interferometric demodulation systems for fiber Bragg grating strain sensors. Theoretical and simulation results are presented and compared with experimental results.     

Boosting Piezo-Catalytic Activity of KNN-Based Materials with Phase Boundary and Defect Engineering

Although the piezo-catalysis is promising for the environmental remediation and biomedicine, the piezo-catalytic properties of various piezoelectric materials are limited by low carrier concentrations and mobility, and rapid electron-hole pair recombination, and reported regulating strategies are quite complex and difficult. Herein, a new and simple strategy, integrating phase boundary engineering and defect engineering, to boost the piezo-catalytic activity of potassium sodium niobate ((K, Na)NbO₃, KNN) based materials is innovatively proposed. Tur strategy is validated by exampling 0.96(K_0.48Na_0.52)Nb_0.955Sb_0.045O₃-0.04(Bi_xNa_4-3x)_0.5ZrO₃-0.3%Fe₂O₃ material having phase boundary engineering and conducted the defect engineering via the high-energy sand-grinding. A high reaction rate constant k of 92.49 × 10⁻³ min⁻¹ in the sand-grinding sample is obtained, which is 2.40 times than that of non-sand-grinding one and superior to those of other representative lead-free perovskite piezoelectric materials. Meanwhile, the sand-grinding sample has remarkable bactericidal properties against Escherichia coli and Staphylococcus aureus. Superior piezo-catalytic activities originate from the enhanced electron-hole pair separation and the increased carrier concentration. This study provides a novel method for improving the piezo-catalytic activities of lead-free piezoelectric materials and holds great promise for harnessing natural energy and disease treatment.     

Indirect Control of Donor/Acceptor Interactions for Highly Efficient Space-Confined Thermally Activated Delayed Fluorescence Emitters

Conformational engineering is essential to further reinforce the luminescent properties of thermally activated delayed fluorescence (TADF) materials featuring through-space charge transfer (TSCT) characteristics. Herein, two TSCT-TADF emitters (8MeDM-B and 8FDM-B) with the methyl and fluorine moieties substituted at the C8 site of the rigid spiro-fluorene bridge is reported. Derivation of the C8 site is first proposed to control the molecular configuration with the ability to indirectly tune the intramolecular interaction between donor and acceptor groups. As a result, 8MeDM-B and 8FDM-B both present small singlet-triplet energy gaps, fast reverse intersystem crossing rates, and high photoluminescence quantum yields. Interestingly, the smaller fluorine atom not the bigger methyl group exhibits more evident electrostatic repulsive force onto the central donor and thus rectifies the central spiro structure. Consequently, the high external quantum efficiency values of 28.8% and 31.7% for 8MeDM-B and 8FDM-B-based electroluminescence devices are achieved, respectively. This study offers a measure for enhancing TSCT-TADF emitters without directly modifying the donor or acceptor.     

TDD-FDD混合组网互操作策略优化和研究

随着用户对移动数据业务的需求不断增长,LTE FDD网络频率、容量等资源不足的问题逐渐凸显,而TD-LTE网络拥有更多的频谱资源,TD-LTE与LTE FDD融合组网可以有效缓解FDD频谱紧张、容量不足的问题,TD-LTE和LTE FDD相互融合并共同发展已成为未来全球移动通信产业的趋势。重点研究了不同场景下,通过参数调整选用不同的TDD/FDD互操作策略,给出该场景下最适合的互操作策略。     

Co3O4 Nanoparticles as Robust Water Oxidation Catalysts Towards Remarkably Enhanced Photostability of a Ta3N5 Photoanode

Despite the fact that Ta₃N₅ absorbs a major fraction of the visible spectrum, the rapid decrease of photocurrent encountered in water photoelectrolysis over time remains a serious hurdle for the practical application of Ta₃N₅ photoelectrodes. Here, by employing a Co₃O₄ nanoparticle water oxidation catalyst (WOC) as well as an alkaline electrolyte, the photostability of Ta₃N₅ electrode is significantly improved. Co₃O₄/Ta₃N₅ photoanode exhibits the best durability against photocorrosion to date, when compared with Co(OH)_x/Ta₃N₅ and IrO₂/Ta₃N₅ photoanodes. Specifically, about 75% of the initial stable photocurrent remains after 2 h irradiation at 1.2 V vs. RHE (reversible hydrogen electrode). Meanwhile, a photocurrent density of 3.1 mA cm^?2 has been achieved on Co₃O₄/Ta₃N₅ photoanode at 1.2 V vs. RHE with backside illumination under 1 sun AM 1.5 G simulated sunlight. The reason for the relatively high stability is discussed on the basis of electron microscopic observations and photoelectrochemical measurements, and the surface nitrogen content is monitored by X‐ray photoelectron spectroscopic analysis.     

采用扫描电镜的ECP技术分析人工合成金刚石晶体中的晶体缺陷

本文应用扫描电镜的ＥＣＰ技术对人造金刚石晶体表面的位错密度，进行了实验分析，并同位错蚀坑分析技术的测量结果进行了比较，结果表明，如采用临界束流强度作为描述ＥＣＰ本征衬度的参数，则它同位错密度间存在明显定量的数学关系，因此上述临界束流强度可用来评价晶体中位错密度的相对变化。     

Molecular beam epitaxial growth of HgCdTe on CdZnTe(311)B

A series of n-type, indium-doped Hg_1−xCd_xTe (x∼0.225) layers were grown on Cd_0.96Zn_0.04Te(311)B substrates by molecular beam epitaxy (MBE). The Cd_0.96Zn_0.04Te(311)B substrates (2 cm × 3 cm) were prepared in this laboratory by the horizontal Bridgman method using double-zone-refined 6N source materials. The Hg_1−xCd_xTe(311)B epitaxial films were examined by optical microscopy, defect etching, and Hall measurements. Preliminary results indicate that the n-type Hg_1−xCd_xTe(311)B and Hg_1−xCd_xTe(211)B films (x ∼ 0.225) grown by MBE have comparable morphological, structural, and electrical quality, with the best 77 K Hall mobility being 112,000 cm²/V·sec at carrier concentration of 1.9×10⁺¹⁵ cm⁻³.     

Conditions of asymptotic stability for cellular neural networks with time delay

In this paper, global asymptotic stability for cellular neural networks with time delay is discussed using a novel Liapunov function. Some novel sufficient conditions for global asymptotic stability are obtained. Those results are simple and practical than those given by P. P. Civalleri, et al., and have a leading importance to design cellular neural networks with time delay.     

10Gbit/s高速串行通道的Hspice仿真研究

随着光传输技术的飞速发展,信号传输速率已经突破Gbit/s级,高速通道的仿真分析已成为系统开发成功与否的关键一环.文章简要介绍了Hspice仿真的基本原理和基本方法,并详细讨论了基于Hspice软件的高速串行通道仿真方法,通过仿真眼图的对比结果说明影响高速通道性能的几个关键环节以及改善通道特性的方法.     

Frequency estimation of sinusiode from wideband using sub-Nyquist sampling

A novel frequency estimation algorithm for wideband signal with sub-Nyquist sampling is proposed in this paper. With the aid of information provided by the auxiliary delayed sampling channel and the aliased frequency estimation for wideband signal with sub-Nyquist sampling, the frequency aliasing due to sub-Nyquist sampling can be solved. This method can reduce the complexity of the overall hardware at the cost of an auxiliary sampling channel. Furthermore, in order to alleviate the computation burden for its practicability, a more simplified algorithm is put forward and its validity is proved by our numerical simulation results. The Cramer-Rao Lower Bound （CRLB） of the frequency estimation is also derived at the end of this paper.