Dispersion Compensation in Externally Modulated Transmission System Using Chirped Fiber Grating

We present an externally modulated NTSC AM-VSB erbium-doped fiber amplifier (EDFA)-repeated system in the 1550 nm region which uses a chirped fiber grating (CFG) as a dispersion compensation device. In contrast to the conventional externally modulated fiber optical CATV systems, either with or without dispersion compensation fiber (DCF), good performances of carrier-to-noise ratio (CNR) S 50 dB, composite second order (CSO) S 74 dB, and composite triple beat (CTB) S 65 dB were achieved for the full channel band after a 100-km single-mode fiber (SMF) transmission.     

Dispersion Compensation in Externally Modulated Transmission System Using Chirped Fiber Grating

We present an externally modulated NTSC AM-VSB erbium-doped fiber amplifier (EDFA)-repeated system in the 1550 nm region which uses a chirped fiber grating (CFG) as a dispersion compensation device. In contrast to the conventional externally modulated fiber optical CATV systems, either with or without dispersion compensation fiber (DCF), good performances of carrier-to-noise ratio (CNR) ≥50 dB, composite second order (CSO) ≥74 dB, and composite triple beat (CTB) ≥65 dB were achieved for the full channel band after a 100-km single-mode fiber (SMF) transmission.     

面外应变对1-3型垂直异质P(VDF-TrFE)基复合薄膜电热性能的调控

考虑1-3型垂直异质铁电P（VDF-TrFE）基复合薄膜结构,利用非线性的热力学理论分析和讨论了平面外应变对复合薄膜电热性能的调控作用. 结果表明,在施加的垂直电场下,平面外应变可以有效地调控电极化、热释电系数、绝热温差等铁电、电热性能. 通过合理的调控平面外应变可以在很大的温度区域范围内获得比纯平面外延薄膜结构更高的绝热温差. 研究结果预示着垂直异质P（VDF-TrFE）基复合薄膜结构在一定的工作温度范围内具有优异的电热性能,在微电源、光通信二极管、红外传感器等微型元件方面有着广泛的应用前景. 关键词： 电热效应 平面外应变 P(VDF-TrFE)复合薄膜 绝热温差     

Studies on synthetic conditions of spray pyrolysis by acids addition for development of highly active Ni-SDC cermet anode

NiO-Ce_0.8Sm_0.2O_1.9 (SDC) composite particles were synthesized by spray pyrolysis method using the starting solutions containing the components for NiO-SDC and various amounts of nitric acid or acetic acid. It was found that the particles had the smooth surface due to the presence of the dissociated acetic acid in the starting solution and the large specific surface area due to the presence of the nitrate ion in the starting solution. SOFC single cell performance using the composite particles for an anode was examined at the operating temperature of 750 °C to clarify the relationship between particle morphology and cell performance. The NiO-SDC composite particles which had smooth surfaces with large specific surface areas gave reproducibly high SOFC performances. It was considered that the morphologies and the specific surface areas of NiO-SDC composite particles played an important role of realizing a high performance anode.     

High power and highly efficient Nd:YAG laser emitting at 1123 nm

A diode-end-pumped continuous-wave (CW) Nd:YAG laser emitting at 1123 nm is realized efficiently in a 25-mm-long cavity. A composite Nd:YAG (cNd:YAG) crystal is selected as the gain medium. With an incident diode power of 26.1 W, an output power of up to 9.3 W is obtained, corresponding to an optical-to-optical conversion efficiency of 35.6%. The laser performances at 1123 nm are compared between composite Nd:YAG and common Nd:YAG crystals. The results show that composite Nd:YAG is a better choice for 1123-nm laser generations.     

CPL复合毛细芯流动性能及工质特性分析

本文分析了两相毛细泵回路(CPL)复合结构毛细芯的流动阻力特性,讨论了影响毛细芯阻力大小的主要因素,计算结果表明,复合毛细芯的流动性能比单一粒径毛细芯优越。另外,还分析了工质物理性质对CPL性能的影响,指出改善工质表面张力特性是研制高性能CPL的方向之一。     

Unsaturated polyester resin (UPR) reinforced with flax fibers,untreated and cold He plasma-treated: thermal,mechanical and DMA studies

Hemp, jute, flax, bagasse, coconut and bamboo fibers are some of the natural fibers that have attracted attention for the preparation of composite materials because of their low cost compared with synthetics fibers (glass, carbon). The performance of a natural fiber as reinforcement in composite materials is linked to its ability in term of adhesion with the synthetic matrix. This depends mainly on the quality of the fiber surface. In order to improve this adhesion, a thin reactive coating is generally used. In this study, cold He plasma treatments have been carried out on reinforcing flax fiber. Composites with unsaturated polyester resin (UPR) have been used with untreated flax fibers and plasma-treated fibers. The data characterizing the thermal, mechanical (dynamic and static) will be presented in order to analyze the efficiency of the He plasma treatment on the composite performances.     

CATV/ROF transport systems based on light injection/optoelectronic feedback techniques and photonic crystal fiber

A directly modulated CATV/radio-on-fiber (ROF) transport system based on light injection and optoelectronic feedback techniques, and photonic crystal fiber (PCF) is proposed and demonstrated. Excellent performances of carrier-to-noise ratio (CNR), composite second order (CSO) and composite triple beat (CTB) were obtained for CATV band; as well as low bit error rate (BER) and third order intermodulation distortion to carrier ratio (IMD₃/C) values were achieved for ROF band. This demonstrated that such a CATV/ROF transport system is very attractive for the fiber backbone applications.     

碳纤维复合材料应用于航天光学遥感器遮光镜筒

碳纤维复合材料作为一种新兴结构材料,它的优异性能提高了航天光学遥感器的结构效率及尺寸稳定性。介绍了某航天光学遥感器遮光镜筒的设计,探讨了碳纤维复合材料应用于航天光学遥感器遮光镜筒需考虑的一些问题,如线膨胀系数、连接接口以及预埋技术等,最后给出了遮光镜筒进行环境模拟试验的实验结果。结果表明,碳纤维复合材料应用于航天光学遥感器是完全可行的,并将得到进一步发展。     

CATV/radio-on-fiber transport system based on direct modulation

A directly modulated CATV/radio-on-fiber (ROF) transport system based on external light injection technique, optical single sideband (SSB) filter, and RF amplifier predistorter is proposed and demonstrated. To the best of my knowledge, it is the first time to transmit CATV and ROF signals simultaneously in a directly modulated form. Good performances of carrier-to-noise ratio (CNR), composite second order (CSO) and composite triple beat (CTB) were obtained for CATV band; and low third order intermodulation distortion to carrier ratio (IMD₃/C), and bit error rate (BER) values were achieved for ROF application.     

Nafion-sulfonated organosilica composite membrane for all vanadium redox flow battery

A novel Nafion-sulfonated diphenyldimethoxysilane (N-sDDS) composite membrane is prepared and employed in vanadium redox flow battery (VRB). Ion exchange capacity, proton conductivity, water transport behavior, and the cell performances are characterized. Fourier transform-infrared and X-ray diffraction analysis indicate that the sulfonated diphenyldimethoxysilane (sDDS) particles are successfully introduced into the Nafion matrix. In VRB single cell test, the VRB with N-sDDS membrane exhibits nearly the same coulombic efficiency as the unmodified Nafion membrane, but higher voltage efficiency than that of the VRB with unmodified Nafion membrane. The VRB with N-sDDS composite membrane keeps a stable performance after 60 times charge–discharge test. In the self-discharge test, the VRB with the N-sDDS membrane presented a lower self-discharge rate than that of the VRB with Nafion membrane. All results show that the addition of s-DDS is a simple and efficient way to improve the conductivity of Nafion, and the composite membrane shows good potential use for VRB.     

CSO/CTB/BER performances improvement in a bi-directional hybrid DWDM system

Experimental verifications of the feasibility of using chirped fiber grating (CFG) as the dispersion compensation device in a bi-directional hybrid dense-wavelength-division-multiplexing (DWDM) system to reduce the dispersion and cross-phase modulation (XPM) induced crosstalk were proposed and demonstrated. Not only channel capacity was increased, but also good performances of carrier-to-noise ratio (CNR) > 50 dB, composite second order (CSO) >72 dB, composite triple beat (CTB) >69 dB and low bit error rate (BER) < 10-9 were achieved in our proposed system over a 50-km single-mode fiber (SMF) transport.     

Structure and Properties of a cis-1,4-Polybutadiene/Organic Montmorillonite Nanocomposite Prepared via In Situ Polymerization

Cis-1,4-polybutadiene (cis-1,4-PB) is one of the most important synthetic rubbers, having superior performances such as wear resistance, cold resistance and high elasticity. However, its mechanical properties, including low tensile strength, tear resistance and thermal stability, limit its application in comparison to natural rubber and butadiene-styrene rubber that have excellent overall performances. Thus, the reinforcing of cis-1,4-PB is a necessity. The dispersion of clay in rubbers on the nanoscale can improve the mechanical, gas permeability and thermal properties of the resulting composites. In this paper, organic montmorillonite (OMMT) clay was dispersed into the cis-1,4-PB matrix via an in-situ polymerization method and the chemical structure, phase morphology, mechanical properties and thermal stability of the composite were investigated. The properties of the composite were analyzed by such techniques as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and thermal gravimetric analysis (TGA). In the in-situ polymerization, a Ni-based catalyst system with the presence of OMMT showed high efficiency and 1,4-selectivity for the polymerization of butadiene. The OMMT could be dispersed in the polymeric matrix on the nanoscale during the polymerization. The interfusion of OMMT had little influence on the thermal stability and the chemical micro-structure of the cis-1,4-PB when the content of cis-1,4 units was more than 95%. The loss tangent of the composite was higher than that of cis-1,4-PB from ?110 to ?55°C, the temperature range examined, and the mechanical properties of the cis-1,4-PB/OMMT nanocomposite (NC) were improved upon the addition of OMMT.     

Long-Distance Transmission of AM-VSB CATV Systems Using Fabry-Perot Laser Diode and Fiber Bragg Grating

This study presented a directly modulated 1550 nm NTSC AM-VSB CATV longdistance transmission system using Fabry-Perot laser diode, optical isolator, fiber Bragg grating, quarter-split-band, and wavelength-division multiplexing techniques. Good carrier-to-noise ratio ( ≥48 dB), composite second-order ( ≥64 dB), and composite triple-beat ( ≥60 dB) performances were obtained after a 100 km standard single-mode fiber transmission. Our proposed system does not use an externally modulated 1550 nm transmitter and a sophisticated stimulated Brillouin scattering suppression technique. It reveals a prominent technique with simpler and more economical advantages than that of externally modulated 1550 nm transmission system.     

Modeling of stress transfer behavior in fiber-matrix composite under axial and transverse loadings

Interface between fiber and matrix as a stress transfer medium determines composite performances in load-bearing structures. For instance, failures in composite are most likely initiated by an accumulation of interfacial cracks allowing little or no stress transfer from the matrix to the fiber and vice versa. This paper studies stress transfer behaviors at the interface subject to axial and transverse loadings using the finite element method. Single fiber surrounded by matrix was modeled by introducing a cohesive zone model (CZM) at the interface taking into account the bonding mechanism. By the proposed technique, plastic deformation in the matrix and exerted friction at the interface was verified to govern the role of stress transfer at the interface. Further, the influence of other fibers in matrix surrounding the model was also discussed.     

氢在不锈钢及氧化铬膜复合体中的稳态渗透实验

本文介绍氢在ＨＲ－１不锈钢基体及镀有氧化铬膜的复合材料中的行为研究，包括基体的准备；膜的制备；用不同手段从不同角度对膜进行的分析测试；膜与基体之间的平均结合力测定；用不锈钢材料构成的高温低压渗透回路的建造、调试、密封性能校准；纯ＨＲ－１基体材料中的氢渗透规律研究；有膜复合材料中氢的稳态迁移过程的表现规律实验结果。它们与国外类似的实验符合得较好；膜的分析测试结果反过来对制膜工艺提供了很有用的反馈信息，氢渗透回路的性能通过了有关专家鉴定，主要技术指标已达到国际同类设备的先进水平。为下阶段更广泛深入的研究奠定了良好的基础。     

High-performance hierarchical cypress-like CuO/Cu<Subscript>2</Subscript>O/Cu anode for lithium ion battery

Composite CuO/Cu₂O/Cu anode for lithium ion battery was designed and synthesized via facile electrodeposition and the subsequent in situ thermal oxidation in air at 300 °C for 1 h. The as-prepared composite CuO/Cu₂O/Cu anode was studied in terms of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), galvanostatic charge/discharge, cyclic voltammetry (CV), and AC impedance. As expected, the composite CuO/Cu₂O/Cu with CuO-rich surface displayed hierarchical cypress-like morphology; furthermore, the hierarchical cypress-like CuO/Cu₂O/Cu anode also delivered satisfactory electrochemical performances. For example, the reversible discharge capacity remained at 534.1 mAh/g even after 100 cycles. The enhanced electrochemical performances were attributed to the hierarchical cypress-like porous structure and the synergistic effect among the composite active copper oxides and highly conductive Cu current collector.     

Preparation of TEMPO-contained pyrrole copolymer by in situ electrochemical polymerization and its electrochemical performances as cathode of lithium ion batteries

Composite electrodes based on the nitroxide free radical-contained pyrrole copolymer (PPy-co-PPy-C-TEMPO) as active material were one-step synthesized by in situ electrochemical polymerization, which was then directly applied as the cathode of lithium ion batteries. The structure, morphology, electrochemical property, and charge-discharge performances of prepared copolymers were characterized by FTIR, SEM, cyclic voltammogram, electrochemical impedance spectroscopy, and galvanostatic charge-discharge testing, respectively. The results demonstrated that PPy-co-PPy-C-TEMPO-based composite cathodes have been successfully prepared by in situ electrochemical method, and the introduction of the nitroxide free radical (TEMPO) could obviously affect the morphology and electrochemical characteristics of the obtained electroactive polymers. And the charge/discharge tests showed that with the introduction of the TEMPO, PPy-co-PPy-C-TEMPO-based composite cathodes exhibited an improved specific capacity of 70.9 mAh g^?1 for PPy-co-PPy-C-TEMPO (4:1) and 62.6 mAh g^?1 for PPy-co-PPy-C-TEMPO (8:1) as measured at 20 mA g^?1 between 2.5 and 4.2 V, which were remarkably higher than that of the pure PPy cathode of 41.0 mAh g^?1 under the same experimental conditions. Also, the obtained PPy-co-PPy-C-TEMPO copolymers demonstrated an acceptable cycling stability during the charge-discharge process. These obtained cell performances for the composite cathodes were attributed to the application of the in situ electrochemical polymerization technology, which enhanced the intimate integration between conductive polymer film and electrode. Furthermore, the introduction of TEMPO-contained pyrrole (Py-C-TEMPO) improved the morphology of the composite cathode, which was in favor of the utilization of active materials and the improved electrochemical performances.     

Two-dimensional modelling of multifrequency piezocomposites

The multifrequency composites of 2-2 connectivity modelled in this work are made with groups of piezoelectric elements of different lateral dimensions, periodically reproduced in the structure. These composites have potential to improve the performances of standard piezoelectric composites with the same materials and ceramic fraction, on account that they have different resonators coupled mechanically along the structure. A one-dimensional model was developed to study their performances in a first approximation. In order to obtain a design model, a two-dimensional model, previously used to describe multielement array transducers, has been extended to the case of 2-2 polymer-piezoceramic composites. Several composite samples, having piezoceramic strips with different width-to-thickness ratios, have been built, and their resonance behaviour compared with the model prediction. Finally, the model has been extended to the case of 2-2 multifrequency composites. For multifrequency composites having in the same composite structure two or three piezoceramic strips with different lateral dimensions, the comparison between experimental and predicted results shows good agreement. The model has been used to optimise a double composite in comparison with a standard one with the same volume fraction and constituents.     

Simulation of the wave-absorbing model of a carbonyl iron / silver-coated core–shell structure

The microwave-absorbing performances of carbonyl iron powder / silver core–shell composite particles are studied on the basis of the electromagnetic scattering theory and the energy conservation law. In addition, a calculation method for reflection loss of the carbonyl iron powder / silver core–shell composite particles with microwave is proposed. The calculated reflection loss of the carbonyl iron powder / silver core–shell composite particles is compared with the experimental results. The findings show that the trend of reflection loss of the carbonyl iron powder / silver composite particles can be predicted which can subsequently provide a relevant reference for future experiment and calculation of the absorbing mechanism of electromagnetic wave-microscopic carbonyl iron powder / silver core–shell composite particles.