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1SQ-250型全方位深松机性能分析 总被引:3,自引:0,他引:3
通过介绍1SQ-250型全方位深松机结构特点,对全方位深松部件的松土原理以及深松后的土壤理化性质变化进行了研究分析。并指出全方位深松部件深松土壤的同时在耕层底部形成鼠道的作用。提出了全方位深松机与其它土壤耕作机具配合使用新的土壤耕作技术措施。图1,参3。 相似文献
64.
河南省大豆品种灰色布局决策研究 总被引:1,自引:1,他引:1
运用作物灰色育种学原理,对1996~1997年河南省大豆品种区域试验资料进行了品种中心灰靶布局分析。在此基础上,提出了河南省不同生态类型区大豆品种灰色布局决策,并对品种区域试验中应当引起重视的问题进行了讨论。表2,参5。 相似文献
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首先分析了雷达目标散射信号特征。在此基础上 ,根据MUSIC算法得到的雷达图像特点 ,通过平滑、量化、增强等适当的图像处理方式对F - 16、HY - 2 0 0 0两种飞机缩比模型在阶梯变频雷达上所获取的雷达图像进行处理 ,并形成雷达二维灰度图 ;最后 ,采用图像矩阵描述方示进行雷达图像的特征提取 相似文献
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Space time trellis coding (STTC) techniques have been proposed to achieve both diversity and coding gains in multiple input multiple output (MIMO) fading channels. But with more transmit antennas STTCs suffer from the design difficulty and complexity increasing. This paper proposes a scheme, named parallel concatenated space time trellis codes (PC-STTC), to achieve the tradeoff between the performances and complexity of STTCs for a large number of transmit antennas. Simulation results and complexity comparison are provided to demonstrate the performance and superiority of the proposed scheme over conventional schemes in fast fading channels in low signal-to-noise ratio (SNR) regions. And an EXIT (extrinsic information transform) chart is given to analyze the iterative convergence of the proposed scheme. It shows that PC-STTC has better iterative convergence in low SNR regions. 相似文献
68.
Adaptive compensating method for Doppler frequency shift using LMS and phase estimation 总被引:1,自引:0,他引:1 下载免费PDF全文
The novel compensating method directly demodulates the signals without the carrier recovery processes, in which the carrier with original modulation frequency is used as the local coherent carrier. In this way, the phase offsets due to frequency shift are linear. Based on this premise, the compensation processes are: firstly, the phase offsets between the base band neighbor-symbols after clock recovery are unbiasedly estimated among the reference symbols; then, the receiving signals symbols are adjusted by the phase estimation value; finally, the phase offsets after adjusting are compensated by the least mean squares (LMS) algorithm. In order to express the compensation processes and ability clearly, the quadrature phase shift keying (QPSK) modulation signals are regarded as examples for Matlab simulation. BER simulations are carried out using the Monte-Carlo method. The learning curves are obtained to study the algorithm’s convergence ability. The constellation figures are also simulated to observe the compensation results directly. 相似文献
69.
The shrinking of cell-size brings significant changes to the wireless uplink of densely small cells (DSCs). A codebook design is proposed that utilizes the strong line of sight (LOS) chan- nel component existing in a DSC system for uplink of the DSC system. To further improve the uplink performance, the high-rank codebook is designed based on singular value decomposition (SVD) due to the unnecessary preservation of strict constant modulus in the DSC system. And according to the simulation result, the proposed codebook leads to significant sum-rate gain and appreciable block error rate (BLER) performance improvement in the DSC system. 相似文献
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To control continuous-time uncertain dynamical systems with sampled data-feedback is prevalent today,but the sampling rate is usually not allowed to be arbitrarily fast due to various physical and/or computational constrains.In this paper,the authors examine the limitations of sampled-data feedback control for a class of uncertain systems in continuous-time,with sampling rate not necessary fast enough and with the unknown system structure confined to a set of functions with both linear and nonlinear growth.The limitations of the sampled-data feedback control for the uncertain systems are established quantitatively,which extends the existing related results in the literature. 相似文献