精度

As a differential detection is used between the intercarrier, the proposed algorithm overcome the high sensitivity to timing error of conventional algorithm and is robust to multi-path. The effect of sample frequency offset can't be ignored in a continuous OFDM system of a large number of subcarriers. The estimation precision of the conventional algorithm is low and the realization is complex. A joint estimation of sample frequency offset and fine frequency offset based on difference operation is proposed. As averaging use a large number of samples in a maximum likelihood algorithm, the estimation precision is very high. The use of difference operation cancel the effect of carrier frequency offset, and the proposed sampling frequency estimation algorithm is robust to carrier frequency offset.

最后，本文对连续系统中的采样频率和载波频率精同步技术进行较为深入的研究，由于子载波数目大的连续OFDM传输系统中，采样频率偏差不可忽视，以往的采样频率估计方法精度低、实现复杂，因此本文提出了一种基于差分处理的采样频率偏差和精载波频率偏差联合估计算法，利用了最大似然算法进行采样频率偏差的估计，由于采用了差分处理方法，消除了载波频率偏差对采样频率偏差估计的影响，采用的最大似然算法对大量样点进行平均化处理，所以，相对以往算法，提出的联合算法估计精度高，而且采样频率偏差估计对载波频率偏差具有鲁棒性。

Analyzing the precision model of intersectant measurement, then the coordinate measuring precision of various position in photoelectric target are calculated.

在分析了测量精度的数学模型后，分别计算了两种布站方式的光电靶面上不同位置点的交汇测量精度。

The main factors effecting on exploration precision of surface wave are analyzed in the light of calculation of phase velocity of surface wave; the merits and demetits of common computing methods for phase velocity between stations and their applied range are discussed and calculation of interstation Green's function for correcting phase is put forward to get the precise phase difference between two stations.

分析了影响面波勘探精度的主要因素，针对计算面波相速度的精度问题，讨论了常用测量台间面波相速度方法的优缺点及其适用范围，并提出通过测量台间格林函数进行相位校正，以得到两台之间的精确相位。

The main factors effecting on exploration precision of surface wave are analyzed in the light of calculation of phase velocity of surface wave; the merits and demetits of common computing methods for phase velocity between stations and their applied range are discussed and calculation of interstation Green's function for correcting phase is put forward to get the precise phase difference between two stations.

分析了影响面波勘探精度的主要因素，针对计算面波相速度的精度问题，讨论了常用测量台间面波相速度方法的优缺点及其适用范围，并提出通过测量台间格林函数进行相位校正，以得到两台之间的精确相位。以合成的高频理论地震图作为记录信号，并在理论地震图上叠加了 2 0 %的随机噪声，利用这些方法分析理论信号，数字实验表明：在相干频率范围内，格林函数方法能够精确测量台间相速度，而互相关法和窄带通滤波互相关法所得结果较为离散。

Band differencing is feasible in water and irrigable field, but it couldnt monitor the changes of whole land use and its precision is the lowest. For the mufti-temporal composite method, it is difficult to choose the exact regions for change detection. Based on the previous accurate classification result, the post classification comparison method gets the best result compared with the other two methods, but also with the hand-on mistakes.

图像差值法对河流水面和水浇地的监测效果比较好，但对所有地类监测结果不令人满意，精度较低；多时相波段复合分类法中，变化土地类型训练区的确定较困难；分类后比较法是在前面土地信息准确提取的基础上进行的分析，精度较高，监测结果图也一目了然，是土地利用动态监测的一种有效方法，但它是在自动识别分类基础上进行的比较，传递了分类产生的误差。

This classifier finished TM landcover by fuzzy logic reasoning, and the unclassified pixels increase K adaptively to be classified; It improved 2.7% and 2.9% in overall accuracy and Kapp coefficient compared with MLC, deceased 1% in Kapp coefficient and no change in overall accuracy compared with self-organizing network.

对拒分类的像元，自适应增加K值使其可分。该方法所得分类精度及Kapp系数与最大似然分类方法结果相比分别提高了2.7%和2.9%；与自组织网络相比，总精度相差不大，而Kapp系数低1%。

ABSTRACT Product design for manufacture and the growing need for mechanism kinematic accuracy demand very advanced science and technology.

面向制造的产品设计和对机构运动精度要求的不断提高是现代科学技术发展的前沿问题，机构的运动精度与制造的并行研究是工程实际的迫切需求。

The work in this paper aims to develop a practical Optical Localizer with high accuracy, this work will aid in the realization of Computer-Assisted Orthopaedic Surgery System.

光学立体定位仪精度高，可靠性强，但是价格昂贵。本文的工作是研制一套实用的，精度较高的光学立体定位系统，为后续的计算机辅助外科手术系统提供帮助。

Based on electro-hydraulic servo control technology and computer control technology, this thesis studies the digital self-adaptative control dynamic electro-hydraulic fatigue testing machine, which is widely applied in several fields, such as aerospace, national defense and military industry, railways equipment, machinofacture, vehicle and ship industry, metallurgy, mine engineering, architectural material, petrochemical industry, plastic and rubber industry, wire and cable industry, etc.

本文以广泛应用于航空航天、国防军工、铁路装备、机械制造、车辆船舶、冶金矿山、建筑建材、石油化工、塑料橡胶、电线电缆等多个领域的电液疲劳试验机为研究对象，以电液伺服控制技术和计算机控制技术为基础，旨在研究高响应、高静态精度、高动态精度、数字化、载荷自适应的疲劳试验机。

First the spectrum-equalized seismic data is equalized by trace, then the result is analyzed with the MESE. If the resolving power of the MESE doesn't reach the precision desire, the equalized data is added with appropriate white noise, then is analyzed with the MESE. Thus the more precise spectral estimate is gotten.

首先对谱均衡后的地震数据作归一化处理，然后对处理结果作最大熵谱估计，若估计结果的谱分辨率精度不能满足要求，则先对归一化的地震记录叠加適当的白噪声，然后再作最大熵谱，这样可以得到较高的估计精度。

This one mode pays close attention to network credence foundation of the businessman very much.

这一模式非常关注商人的网络信用基础。

Cell morphology of bacterial ghost of Pasteurella multocida was observed by scanning electron microscopy and inactivation ratio was estimated by CFU analysi.

扫描电镜观察多杀性巴氏杆菌细菌幽灵和菌落形成单位评价遗传灭活率。