The main works and innovations of this thesis are as follows : ( 1 ) based on the oversampling of ofdm frequency response , this paper proposes a channel estimator which combines the comb - pilot - tones partitioning and the fourier transform with the same pilot symbol samples 具体而言，主要有以下六个方面的工作和创新点： ( 1 )利用在ofdm系统中信道的频域响应是过采样的特性，提出了在频域内用均匀梳状分布的导频符号和与导频符号数相同点的傅里叶变换相结合的信道估计方法。
Firstly , this paper introduces the basic structure of narrow band fir digital filters . secondly , it analyses the components of narrow band fir digital filters , which conclude cic filter , hbf filter , resampling techniques . based on these analyses , the paper gives the full structure of narrow band fir digital filters and analyses its characteristics , which are frequencies response , anti _ aliasing and anti _ image 本文首先简单介绍了窄带fir滤波器的基本结构，然后对窄带fir滤波器的各组成部分进行了详细分析，内容包括：积分梳状滤波器( cic )的特性和设计，半带滤波器( hbf )和整形滤波器的特性和设计，重采样技术的原理与实现。
Experimental sample dct375 with collector - combed structure has better parameter such as icm , pq , pd and / r etc . than traditional - structure devices and overseas devices of the same kind . collector - combed structure technology opens up a new way for the further research of new high - frequency , microwave power devices 研制出的梳状集电结(基区)结构试验管dct375 ，其最大电流容量、最大输出功率、最大耗散功率以及频率特性等电参数明显比传统结构器件和国外同类产品有大的提高。
Electro - conductive fingers of gripper are connected to ground , in order to release the electric charges on the surface of fingers and gripping objects . continuous s - shaped flexures in finger would decrease the stiffness of gripping arm , and slove the contradiction between huge elastic modulus and small surface electrostatic force 本文设计了大深宽比梳状静电驱动形式的微夹持器，采用了导电型并接地连接的微夹持臂，对被操作对象无特殊要求，且可防止静电对操作的影响。
Abstract : unsaturated polyester with low shrinkage composied of anti - shrinking agent , thermoplastics , dispersion - stabilizer , a kind of graft copolymer made from styrene and saturated polyester , shaped like a comb for its molecular structure and upr in certain structure and some factors effecting on low shrinkage were introduced in this paper 文摘:研究了当用热塑性树脂作为不饱和聚酯树脂低收缩剂时，合成了以苯乙烯为主链，聚酯为枝链的梳状接枝共聚物，作低收缩剂的分散稳定剂，配合相应组成的不饱和聚酯树脂得到了具有低收缩特性的不饱和聚酯组成物。
The flow characteristics , distributions of current density and chemical components , and the performance of these two different designs are calculated and compared . the flow and mass transport characteristics are analyzed in detail , which indicate that strong forced convection is produced in the interdigitated flow field , which consist of dead - end gas channel that force the gases through the porous electrodes . results of comparison show that forced convection induced by the interdigitated flow field in the diffusion layer effectively enhances mass transport of reactants and products , thus leading to a higher cell performance and the limiting current density 在传统流道设计的pemfc中，反应物从流道到催化层的供应和生成物从催化层到流道的排出主要是以扩散为主，而在交叉梳状流道设计中，以流动带动的对流传递则占据了主导地位，而且这种以对流为主的传递机理大大提高了反应物和产物传递速率，从而有效地改善了电池的极限电流密度和极化性能等特性。
Wdm has promoted greatly the development of optical communications , optical net based on wdm technology will become the main transmitting flat roof in telecom net . in wdm , with increasing the channel density , a new kind of optical component , interleaver , emerges as the times require . in this paper , several main interleaving technologies are analyzed quite deeply , and mgti interleaver is investigated experimentally , one prototype device with better experiment results is achieved 波分复用技术( wdm )对于光通信技术的发展起到了巨大的推动作用，以dwdm技术为核心的光传送网将成为电信网的主要传送平台。在密集波分复用技术中，随着信道复用密度的提高，一种新型光器件? ?光学梳状滤波器( interleaver )应运而生。
And the results of calculation and numerical simulation indicate , without increasing the intrinsic collector - junction area of power devices , collector - combed structure helps to raise the intrinsic heat - dissipating area and base ' s perimeter , improve heat - dissipating method of each cell of the chip , enhance the distribution uniformity of junction temperature and current of each cell of the chip , reduce the thermal resistance and raise the dissipation power pd and output power p0 , fairly well relax the contradiction among frequency , out - put power and dissipation power of the devices , and further improve the devices " property against second breakdown 而计算分析和二维数值模拟分析结果表明：梳状集电结(基区)结构在不增加器件本征集电结面积的条件下，增大了器件的本征散热面积和基区周长，改进了每个子器件单元内的散热方式，提高了单元内结温和电流分布的均匀性，降低了器件的热阻，增大了器件的耗散功率和输出功率，较好地缓解了目前传统结构中频率与功率、功耗的矛盾，并有利于改善器件抗二次击穿的性能。
Secondly , we propose and demonstrate experimentally a novel multi - wavelength erbium - doped fiber ring laser by using a mach - zehnder fiber interferometer and composite cavity . as a result , simultaneous multi - wavelength oscillations with narrow linewidth and equal wavelength span are obtained in room temperature . this device has advantageous of simple design fabrication and low cost et al 进一步，我们设计了一种新颖的多波长掺铒光纤环形激光器，这种激光器是利用mach - zenhder ( m - z )光纤型干涉仪作为梳状滤波器，并且与复合腔共同选频，获得了窄线宽、等间隔的多波长同时输出，这种激光器具有在常温工作，结构简单，成本低等优点。
3 . the principle of the interleaver based on the interference of polarized light is analyzed theoreticallyand the interleaver architecture of this kind is presented . a 50ghz interleaver is designed and the two series of interleaved spectrum like cosine function is obtained experimentally ; by using the tandem of two birefringent crystals with different optical path difference , we get the flattop spectrum 3 、分析了pbi型interleaver滤波器的基本原理，给出了一种pbi型interleaver滤波器结构；设计了50ghz光学梳状滤波器，实验得到了该器件两组交错分波类余弦输出光谱；采用不同光程差的晶体级联方案，实现了输出光谱平顶化。
