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目的 :探讨尿沉渣显微镜检查标准化方法在临床实际工作中的应用。方法 :选用同份尿标本经标准化处理后尿沉渣分别用普通玻片法做尿沉渣镜检与 FAST- READ1 0尿沉渣定量分析板做显微镜定量计数。结果 :普通玻片法根据数量不同分为四组 :WBC结果为 2～ 6 /HPF、1 0～ 2 0 /HPF、2 5～ 3 0 /HPF、40～ 5 0 /HPF,定量计数结果为 8～ 40 /μl、80～ 1 40 /μl、2 0 0～ 2 4 0 /μl、3 0 0～ 5 0 0 /μl;RBC结果为 2～6 /HPF、1 0～ 1 5 /HPF、2 5～ 3 5 /HPF、40～ 5 0 /HPF,定量计数结果为 1 5～ 3 0 /μl、1 0 0～ 1 3 6 /μl、2 4 0～ 3 4 0 /μl、5 0 0～ 90 0 /μl;上皮细胞计数结果为 2～ 6 /HPF、8～ 1 2 /HPF、1 5～ 2 0 /HPF、2 5～ 3 0 /HPF,定量计数结果为 8～ 2 6 /μl、40～ 1 0 0 /μl、1 80～ 2 2 0 /μl、3 0 0以上。结论 :过去采用的普通玻片法不规范 ,不标准。而目前应用与推广的尿沉渣定量分析法是一种规范化、标准化方法 ,此法优于玻片法。 相似文献
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A simple channel estimator for space-time coded orthogonal frequency division multiplexing (OFDM) systems in rapid fading channels is proposed. The channels at the training bauds are estimated using the EM (expectation-maximization) algorithm, while the channels at the data bauds are estimated based on the method for modelling the time-varying channel as the linear combination of several time-invariant "Doppler channels". Computer simulations showed that this estimator outperforms the decision-directed tracking in rapid fading channels and that the performance of this method can be improved by iteration. 相似文献
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A channel estimation approach for orthogonal frequency division multiplexing with multiple-input and multipleoutput （MIMO-OFDM） in rapid fading channels is proposed. This approach combines the advantages of an optimal training sequence based least-square （OLS） algorithm and an expectation-maximization （EM） algorithm. The channels at the training blocks are estimated using an estimator based on the OLS algorithm. To compensate for the fast Rayleigh fading at the data blocks, a time domain based Gaussian interpolation filter is presented. Furthermore, an EM algorithm is introduced to improve the performance of channel estimation by a few iterations. Simulations show that this channel estimation approach can effectively track rapid channel variation. 相似文献
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Multiple antenna wireless systems can provide larger channel capacity and enable spatial diversity to combat fading. In this paper we conduct an investigation into the design of coded space-time system obtained by serially concatenating channel code module and space-time code module with an interleaver in between. As an example, the system is constructed by employing low decoding complexity turbo-SPC （single parity check） code as outer module and linear complex field space-time code as inner module, which achieves full diversity and lossless equivalent channel capacity. Simulation results prove that our designed system performs well and it only loses 0.8 dB from multiple-input multiple-output （MIMO） capacity at BER = 10^-5 in the case of information bit length 6048. Compared with turbo code-based systems, it also has lower error floor. 相似文献
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INTRODUCTION High data rate and high quality multimedia ser- vices are required in beyond third generation (B3G) and fourth generation (4G) mobile communications. Space-time coding scheme has been proposed (Tarokh et al., 1998; 1999) to achieve higher capacity and data rate. So far, most research on space-time coding assumed that accurate channel estimations are available at the receivers. However, accurate channel estimation is difficult and too many training symbols are required in a r… 相似文献
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The downlink frame structure for beyond 3G mobile communication systems is presented. Beyond 3G systems utilize the OFDM technique. However, a problem encountered in OFDM is that channel dispersion destroys orthogonality between carriers, caushag inter-symbol interference. It is also sensitive to high peak to mean power ratio （PAPR）. Therefore it spends much time on obtaining frequency, time, and frame synchronization. This paper proposes to add a frame synchronization channel in the time domain to overcome the shortcoming of OFDM. As transmitter diversity improves the system performance, beyond 3G systems employ space-time block coded （STBC）. Fast cell search algorithm including slot synchronization, frame synchronization and cell ID identification is then discussed, which is based on the frame synchronization channel in transmitter diversity systems. Detection and false alarm probabilities in AWGN and Rayleigh channels are analyzed, and the mean acquisition time is obtained. Computer simulations are conducted to evaluate the performance of the cell search algorithm under different channel conditions. 相似文献