嵌入式智能家居系统连入Internet的研究和实现

智能家居系统如何接入Internet是一个难点问题。在对现有嵌入式系统连入Internet技术分析的基础上,结合嵌入式Internet技术、计算机网络技术、电力线数据通信技术,设计出一种高性价比的电力线载波智能家庭网关系统。最后给出了智能家庭网关系统的应用实例,实现了对智能家电的远程监控。     

基于矢量旋转的MC DS-CDMA信号定时跟踪方案

针对MC DS-CDMA系统对定时误差敏感的特点,提出一种全数字定时跟踪方案.通过对准时支路相关值进行矢量旋转,检测定时误差并实现定时调整跟踪.理论分析和数值结果表明,与传统方案相比,在不牺牲性能的前提下,新方案成倍降低了实现复杂度.硬件电路实现验证了方案的可行性.     

Simulation of MC-CDMA in the Presence of Timing Errors

1　ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｔｈｉｒｄｇｅｎｅｒａｔｉｏｎｏｆｍｏｂｉｌｅｃｏｍｍｕｎｉｃａｔｉｏｎｓｙｓｔｅｍｓｗｉｌｌｂｅａｂｌｅｔｏｐｒｏｖｉｄｅａｗｈｏｌｅｖａｒｉｅｔｙｏｆｖｏｉｃｅ ,ｄａｔａａｎｄｖｉｄｅｏｓｅｒｖｉｃｅｓｆｏｒｔｈｅｕｓｅｒ.Ｍｕｃｈｒｅ ｓｅａｒｃｈｈａｓｂｅｅｎｄｏｎｅｏｎｔｈｅｕｓｅｏｆｗｉｄｅｂａｎｄ ＣＤＭＡｆｏｒｓｕｃｈｓｙｓｔｅｍｓ.ＴｈｅｍａｉｎａｄｖａｎｔａｇｅｓｏｆＣＤＭＡａｒｅｗｅｌｌｋｎｏｗｎ ,ｈｏｗｅｖｅｒ,ｉｔｓｃａｐａｃｉｔｙｉｓｌｉｍ…     

Performance Analysis of MC-CDMA in the Presence of Carriers Phase Errors

1　ＩｎｔｒｏｄｕｃｔｉｏｎＲｅｃｅｎｔｌｙ ,ｇｒｅａｔａｔｔｅｎｔｉｏｎｈａｓｂｅｅｎｐａｉｄｔｏｔｈｅｄｅｓｉｇｎｏｆｗｉｒｅｌｅｓｓｓｙｓｔｅｍｓｆｏｒｈｉｇｈｄａｔａｒａｔｅａｐｐｌｉｃａ ｔｉｏｎｓ.Ａｍｕｌｔｉｃａｒｒｉｅｒ (ＭＣ)ＣＤＭＡｓｙｓｔｅｍ[1～ 4] ｅｍ ｐｌｏｙｉｎｇｏｒｔｈｏｇｏｎａｌｆｒｅｑｕｅｎｃｙｄｉｖｉｓｉｏｎｍｕｌｔｉｐｌｅｘｉｎｇ(ＯＦＤＭ) [5～ 1 0 ] ｉｓａｍｏｒｅｓｕｉｔａｂｌｅｃａｎｄｉｄａｔｅｆｏｒｈｉｇｈ ｂｉｔ ｒａｔｅａｐｐｌｉｃａｔｉｏｎｓ,ｂｅｃａｕ…     

A Difference Method of the Gravity Center with Double Pilots for the MC-CDMA System

1　ＩｎｔｒｏｄｕｃｔｉｏｎＦｏｒｔｈｅＭＣ ＣＤＭＡｍｏｂｉｌｅｃｏｍｍｕｎｉｃａｔｉｏｎｓｙｓ ｔｅｍｂａｓｅｄｏｎｏｒｔｈｏｇｏｎａｌｆｒｅｑｕｅｎｃｙｄｉｖｉｓｉｏｎｍｕｌｔｉ ｐｌｅｘｉｎｇ ,ｔｈｅｓｙｎｃｈｒｏｎｉｚａｔｉｏｎｏｆｔｈｅｃａｒｒｉｅｒｆｒｅｑｕｅｎｃｙａｔｔｈｅｒｅｃｅｉｖｅｒｍｕｓｔｂｅｐｅｒｆｏｒｍｅｄｖｅｒｙａｃｃｕｒａｔｅｌｙ ,ｏｒｔｈｅｒｅｗｉｌｌｂｅａｌｏｓｓｏｆｏｒｔｈｏｇｏｎａｌｉｔｙａｍｏｎｇｔｈｅｓｙｍｂｏｌｓａｎｄａｍｏｎｇｔｈｅｓｕｂ ｃｈａｎｎｅ…     

Structure formation in monolayers composed of hard bent-core molecules

ABSTRACT

We investigate the role of excluded volume interactions instabilising different structures in monolayers filled with bent-shaped molecules using the Onsager type of density functional theory supplemented by constant-pressure Monte-Carlo simulations. We study influence of molecular features, like the apex angle, thickness of the arm and the type of the arm edges on the stability of layered structures. For simple molecular shapes taken the observed phases are dominated by the lamellar antiferroelectric type as observed experimentally, but a considerable sensitivity of the ordering to details of the molecular shape is found for order parameters and wave vectors of the structures. Interestingly, for large opening angles and not too thick molecules, a window of stable nematic splay-bend phase is shown to exist.     

Spreading code allocation strategy for downlink multicarrier code division multiple access transmission in a correlated Rayleigh fading channel

In this paper, we address the problem of multiple access interference (MAI) in a downlink multicarrier code division multiple access system. Because in the realistic case of correlated faded subcarriers, MAI greatly depends on the codes assigned to users, one way of improving performance without increasing receiver complexity consists in an appropriate code selection. We propose a code allocation strategy with the following properties: possible use with any code sequence and equalizer, low complexity, and efficient management of load variations. The allocation problem is formulated as a minimization problem of a cost function related to MAI. First, we provide analytical expressions for the channel frequency correlation function after maximum ratio combining, equal gain combining, and minimum mean square error equalization and for the MAI power. Then, by approximating these expressions, we define a simple cost function and build an iterative algorithm on the basis of the minimum maximum criterion to select the spreading codes. Finally, a complete analysis of the allocation efficiency is provided versus key parameters, in particular, the degree of correlation between the faded subcarriers, the system load, and the equalization techniques. Copyright © 2012 John Wiley & Sons, Ltd.     

基于红外光电传感器的智能寻迹小车设计

寻迹小车可以看作是缩小化的智能汽车,对智能汽车的研究有一定的借鉴意义。采用飞思卡尔公司的MC9S12DG128B作为核心控制芯片,设计了通过红外光电传感器检测路径信息的智能寻迹小车。该系统由处理器模块、路径识别模块、电机驱动模块、舵机驱动模块、车速检测模块、液晶显示模块与电源模块等组成。实际应用表明,该小车可以在专门设计的跑道上快速平稳地实现寻迹功能。     

基于改进MC算法的CT/MR图像三维重建

针对MC(Marching Cubes)算法重建后模型表面的不光滑性和模型表面三角面片数量大的缺点,提出了在保证一定精度的前提下减少小面片的处理方式。通过对等值面进行三维空间上的方向平滑来代替等值面上的三维坐标平滑,达到了提高模型表面平滑性的目的。以边删除算法为基础,设计了网格简化算法,实现了模型表面的网格简化。以喉管和心血管两组磁共振(Magnetic Resonance,MR)体数据为例进行三维表面重建的结果表明,平滑后的三维显示效果有了显著改善,显示的结构细节清晰度与真实感明显提高。模型的网格简化90%后,依然能保持原模型的特征和较好的视觉效果,并大大提高了实时交互绘制的能力,明显缩短了交互操作时间。     

多通道A/D转换控制模块的设计与实现

提出了利用MC143150 Neuron芯片和Burr-Brown公司生产的12位串行模数转换器ADS7844实现多通道A/D转换控制模块的设计与实现方法。介绍了MC143150 Neuron芯片和12位串行模数转换器ADS7844的硬件结构与工作原理,以及运用Neuron C语言开发多通道A/D转换控制模块,对数据转...