Flame retardancy properties of α-zirconium phosphate based composites

α-Zr phosphate (hereafter referred to as ZrP) based composites were prepared by melt blending in order to improve the flame retardancy properties of polyamide 6 (PA6), polyethylene terephthalate (PET), polypropylene (PP) and ethylene vinyl acetate copolymer (EVA). Different morphologies are distinguishable by electron microscopy: PA6-ZrP seems to be a nanocomposite by Transmission Electron Microscopy (TEM) whereas PET-, PP- and EVA-ZrP blends appear micro-composites by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) analyses. ZrP acts as flame retardant in PA6 reducing the total heat evolved and consequently the heat release rate during the combustion measured by cone calorimetry. Moreover, ZrP reduces the flammability of PET and EVA acting in synergistic effect with phosphorous based flame retardants. Indeed, it is showed that it is possible to reduce the amount of phosphorous flame retardant adding ZrP to reach UL94 classification V0 for both polymers.     

离子液体中聚对苯二甲酰己二胺的合成与表征

以咪唑类离子液体为溶剂、亚磷酸三苯酯(TPP)为活化剂合成了聚对苯二甲酰己二胺(PA6T),考察了反应时间、反应温度、TPP用量和单体浓度对分子量的影响,得到特性黏数[η]为0.49～1.68dL/g的聚合物.与以水为介质在高压釜中(温度220℃、压力1.8MPa、反应5h)合成的预聚物(prePA6T)及再固相缩聚8h的产物(PA6T-SSP-8h)相比,离子液体中容易获得特性黏数[η]高的聚合物(PA6T-IL)、聚合时间明显缩短且反应温度降低.     

螺旋手性聚乙炔衍生物

聚乙炔是链对称的共轭大分子,在内外界的微扰下,其主链的对称性能够被破坏,而产生螺旋手性结构。本文综述了螺旋手性聚乙炔衍生物的合成和功能方面的研究进展,着重介绍了螺旋手性聚乙炔衍生物在简单的外界刺激（溶剂,酸碱度,温度和添加剂等）下,表现出许多功能特征,如刺激响应性、显色、光/电致发光,仿生结构,分子识别等。     

基于非正交多址接入中继通信系统的功率优化

针对基于非正交多址接入(NOMA)技术的中继通信系统,在兼顾系统性能与计算复杂度的基础上,该文提出一种结合统计信道信息(S-CSI)和瞬时信道信息(I-CSI)的混合功率分配策略(H-PAS)来有效实现上述折中。仿真结果表明,NOMA方案在H-PAS策略下,一方面比单纯利用S-CSI时的传统正交多址接入技术具有更高的频谱效率;另一方面在和速率差别不大的情况下,又比单纯利用I-CSI时的NOMA方案具有更低的信令开销和计算复杂度。     

A 2.4 GHz power amplifier in 0.35 μm SiGe BiCMOS

This paper presents a 2.4 GHz power amplifier (PA) designed and implemented in 0.35 μm SiGe BiCMOS technology. Instead of chip grounding through PCB vias, a metal plate with a mesa connecting ground is designed to decrease the parasitics in the PCB, improving the stability and the gain of the circuit. In addition, a low-pass network for output matching is designed to improve the linearity and power capability. At 2.4 GHz, a P_(1dB) of 15.7 dBm has been measured, and the small signal gain is 27.6 dB with S_(11) < -7 dB and S_(22) < -15 dB.     

当前中国体育场馆扩声系统设计概要

根据目前中国体育场馆扩声系统建设的新特点,结合各单项体育运动的不同要求,通过合理适用的系统架构以及扬声器选型、布局方式,寻求当前体育场馆扩声系统的通常解决方案,并对其发展前景进行了预测。     

一种基于双通道非线性反馈架构的模拟域功率放大器线性化技术

该文提出一种在模拟域抑制功率放大器(PA)非线性失真的双通道非线性反馈架构,以改善PA线性度,减少邻道泄露。在该架构中,用于抑制非线性的电路包含非线性提取环路和反馈调整环路。非线性提取环路通过耦合器提取PA输入和输出信号,进行幅度和相位对齐后抵消线性信号,保留PA产生的非线性失真。反馈调整环路包含两条独立反馈通道,且信号通过非线性提取环路和反馈调整环路中两条通道分别反馈后的总时延具有两倍关系,使反馈环路呈现2阶Delta-Sigma结构形式,相比于单通道非线性反馈架构具有更好的失真抑制性能。并且通过所提方法配置反馈通道参数,可以实现不同目标频点下非线性失真的灵活抑制。最后设计了一个使用CMPA0060002F商用功放芯片的实验平台,对于带宽为40 MHz,载频为780 MHz的测试信号,在当前6 ns的硬件反馈时延条件下,可以使邻道功率泄露比(ACLR)单边带改善11 dB或双边带改善6 dB,且通过减小反馈时延能够取得更好的性能。     

多参考点三步搜索法快速稳像算法

针对数字稳像（DIS）算法的实时实现，提出了基于三步搜索（TSS）法和投影算法（PA）的快速DIS算法，并在TSS法的每一步保留多个参考点以提高稳像精度使其更接近于全搜索块匹配法（FS-BM）。仿真实验表明，该算法具有较高的运动估计精度及更快的运算速度，可用于较复杂运动估计模型的实时处理。     

Micronization of the officinal component emodin via the SEDS process through prefilming atomization

The micronization of emodin in a mixed solution of dichloromethane and methanol by the Solution Enhanced Dispersion by Supercritical Fluids through Prefilming Atomization (SEDS‐PA) process has been successfully performed. Morphologies and particle sizes (PSs) of the emodin microparticles were analyzed by scanning electron microscopy. The results of micronization show that the acicular or rod‐like emodin crystals with PSs of about 3‐10 µm wide and 100‐300 µm long have successfully been micronized to needle‐like, rod‐like, twisted fiber‐like and coalesced net‐like microparticles with PSs of about 0.1‐1.0μm wide and 2‐40μm long by the SEDS‐PA process. The effect of technological conditions on micronization has been studied. With the increase of initial solution concentration and temperature, the PSs of emodin microparticles increase. With the increase of solution flow rate and pressure, the PSs of emodin microparticles decrease. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Multi-Layer Pipes for Hydrocarbons Conveyance

The replacement of metals with plastics in piping systems is a well established practice in a vast range of public and industrial applications. However, difficulties still exist, mainly related to the limited chemical resistance of the polymers commonly used in pipe manufacturing to some conveyed fluids. This prevents using plastic pipes in important applications such as the transport of liquid hydrocarbons, particularly in oil fields. The use of chemically resistant polymers, such as fluorinated polyolefins, is precluded by high cost and poor mechanical properties. Co-extrusion of multi-layer pipes carrying an internal chemically resistant liner can be a viable alternative capable to extend the use of plastic pipes to refining and chemical industries. An experimental PE/PA multi-layer pipe has been developed whose resistance to diffusion and mechanical properties have been tested. Tests in real oil fields confirm the good performance of the new pipes.