基于MIMO-OFDM系统的盲源分离算法研究

为了实现使用OFDM调制的MIMO系统的盲源分离问题,提出了在接收端使用Nyquist频率对接收到的信号进行采样的,从而将原始的MIMO-OFDM系统盲源分离问题转变为N组的独立分量分离的问题.通过将FastICA算法扩展到复数域,在频域中对每一组相同子载波上的信号进行独立分量分析,最终实现信号的盲分离.仿真实验获得的结果证实了该方案具有良好的恢复效果,且算法收敛的迭代次数只需要8～10次.     

基于WebGL的交互平台设计与实现

介绍了WebGL技术及其应用框架Three.js,描述了交互平台基本架构搭建和各个功能模块的设计与实现过程,并针对OBJ格式的3维模型提出一个模型加载算法解析模型的顶点、面和法向量等数据,然后把三维模型加载到网页平台中来,最后本文对平台进行了跨浏览器测试和模型载入速度测试,测试结果表明系统不需修改任何代码就能直接运行在Firefox、Chrome和Opera这3大主流浏览器上,并且模型载入速度较快,显示效果流畅。     

基于简化干扰观测器的光电平台稳定与评估

单纯采用经典的比例积分（proportion integration,PI）校正难以进一步提高航空光电平台惯性稳定性能。本文分析了影响稳定精度的主要因素,设计了基于简化干扰观测器（disturbance observer,DOB）的航空光电平台稳定控制算法。该方法由DOB和PI控制器构成,其中DOB 采用陀螺反馈,利用等效变换实现,无需求取被控系统的逆模型。此外,本文提出一种基于隔离度测试的航空光电平台稳定性能评价方法。在实际系统中进行了惯性稳定实验,采用所提出的稳定控制方法获得了10 μrad（RMS）的稳定精度,并且采用新方法的隔离度测试结果在30 Hz频带内的姿态扰动下较传统PI控制均有显著的提高。     

基于电阻取样法测量变压器中性点直流电流的传感器设计与应用

基于电阻取样法设计了用于测量中性点直流的直流传感器。基于电阻取样法的测量原理和双积分型A/D转换器调理电路工作原理,实现了变压器不停电安装中性点电流在线监测装置。设计的直流传感器输出特性与温度基本呈线性关系,便于在线对传感器进行校正。当测量电流大于10 A时,其测量误差为2%;当测量电流小于10 A时,其测量误差小于0.2 A。设计的直流传感器成功运用于现场测量,监测数据表明其运行可靠。     

基于涡流斥力机构的低压交流接触器技术

针对传统电磁机构励磁控制交流接触器的不足,利用涡流斥力机构结构简便且励磁斥力建立时间短、机构动作快速的特点,提出涡流斥力机构的新型交流接触器技术,应用能量守恒法建立涡流斥力的数学模型及其动态仿真技术。设计了基于CJ40-100A本体结构的新型交流接触器样机。经仿真分析和样机动态测试,验证了新型交流接触器在触头接通与分断控制基础上的快速动作特性。     

Sustained-release pellets of nifedipine using microcrystals combined with MCC-based matrix

The purpose of this study was to prepare sustained-release pellets of nifedipine (NSPs) based on MCC matrix. Wet-milling and extrusion-spheronization techniques were employed to prepare the microcrystals and pellets, respectively. The drug release mechanism and the influencing factors were investigated. After milled with HPMC (E5), the mean particle size of nifedipine in co-grinding mixture (CGM) was 5?μm, which is 15-fold smaller than that of raw material. DSC, X-ray powder diffraction and microscopic observation confirmed the microcrystals of drug were maintained in the CGM. With increased milling time and the content of HPMC, the dissolution rate was greatly enhanced compared with the raw material. The NSPs prepared by MCC and the CGM, which was obtained by cogrinding nifedipine with 5% HPMC solution for 210?min, exhibited sustained release pattern within 8?h. Nifedipine release from MCC-based NSPs followed the Korsmeyer model and closely related to the microstructure of pellet. High stability of NSPs was confirmed after 6 months of accelerated stability test. Using commercially available sustained product as reference, bioequivalence study in beagle dogs was executed and two formulations were bioequivalent. This sustained release pellet formulation of nifedipine was advantageous with convenient and easy scaled-up preparation process.     

Potentials of proniosomes for improving the oral bioavailability of poorly water-soluble drugs

Objective: The objectives of this study were, first, to develop a free-flowing and stable proniosome formulation for poorly water-soluble drugs such as vinpocetine; and second, to estimate its bioavailability as oral drug delivery system.

Methods: The proniosomes consisting of span60, cholesterol, sorbitol and vinpocetine were prepared by a novel approach. After the proniosomes were contacted with water, the suspension of vinpocetine-loaded niosomes formed automatically. The proniosomes and reconstituted niosomes were evaluated for their physicochemical characteristics, in vitro drug dissolution and release, integrity and stability at different GI tract pH conditions, in situ single-pass intestinal perfusion and in vivo bioavailability.

Results: The proniosome powder exhibited excellent flowability. The reconstituted niosomes with high drug entrapment efficiency (89.67?±?3.28%) showed spherical morphology with smooth surface under transmission electron microscope (TEM). X-ray diffraction (XRD) indicated that the drug was in an amorphous or molecular state in proniosome powder. In vitro dissolution and release study, proniosomes did enhance the dissolution and release rate compared to vinpocetine suspension in phosphate buffer solution (pH 7.2). Proniosome-derived niosomes could keep their integrity and stability at different GI tract pH conditions. The in situ single-pass intestinal perfusion indicated that encapsulation of vinpocetine into niosomes could largely improved the absorption of vinpocetine. The AUC(0?∞) of F2 and F3 was about 4.0- and 4.9-fold higher than that of the vinpocetine suspension, respectively. The results demonstrated the proniosomes indeed remarkably enhanced the oral bioavailability of vinpocetine.

Conclusion: This study suggested the potential of proniosomes as stable precursors for the immediate preparation of niosome carrier systems.