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结合工程实践,针对已建多座刚架拱桥出现不同程度病害的问题,分析了刚架拱桥出现病害的原因,提出了相应的防治对策,以期为同类似桥梁的设计与施工提供参考。 相似文献
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To implement the primary signal without interference in cognitive radio systems, cognitive radios can detect the presence
of the primary user in low SNR. Currently, energy detector is the most common way of spectrum sensing because of its low computational
complexity. However, performance of the method will be possibly degraded due to the uncertainty noise. This paper illustrates
the benefits of one-order and two-order cyclostationary properties of primary user’s signals in time domain. These feature
detection techniques in time domain possess the advantages of simple structure and low computational complexity comparing
with spectral feature detection methods. Furthermore, performance of the one-order and two-order feature detection is studied
and the analytical results are given. Our analysis and numerical results show that the sensing performance of the one-order
feature detection is improved significantly comparing with conventional energy detector since it is robust to noise. Meanwhile,
numerical results show that the two-order feature detection technique is better than the one-order feature detection. However,
this benefit comes at the cost of hardware burdens and power consumption due to the additional multiplying algorithm. 相似文献
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Introduction OFDM[1]is a special case of multicarrier trans-mission, where a single datastream is transmittedover a number of orthogonal subcarriers. Becausethe symbol duration increases for the lower rateparallel subcarriers, the relative amount of disper-sion in time caused by multipath delay spread is de-creased. Intersymbol interference is eliminated al-most completely by introducing a guard time in ev-ery OFDM symbol. Due to these advantages,OFDM is widely exploited for the communica… 相似文献
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A novel practical cooperative diversity method for power-limited wireless sensor network system was proposed. At first, the system model was presented and the cooperation problem is formulated under the minimum outage probability criterion, then the focus was put on the power efficiency of system, such as the relay selection, cooperation strategy and power allocation etc. At last the uniform procedure of the proposed method was given. The results of the simulation clearly demonstrate that our method not only has the properties of simple operation and wide applying scope, but also outperforms those of current classical methods on the aspect of outage probability under the basis of the same power limitation. 相似文献
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