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A novel DOA estimation algorithm using directional antennas in cylindrical conformal arrays 被引量:9
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作者 xiao-feng gao Ping Li +2 位作者 Xin-hong Hao Guo-lin Li Zhi-jie Kong 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2021年第3期1042-1051,共10页
In this paper, a novel direction of arrival(DOA) estimation algorithm using directional antennas in cylindrical conformal arrays(CCAs) is proposed. To eliminate the shadow effect, we divide the CCAs into several subar... In this paper, a novel direction of arrival(DOA) estimation algorithm using directional antennas in cylindrical conformal arrays(CCAs) is proposed. To eliminate the shadow effect, we divide the CCAs into several subarrays to obtain the complete output vector. Considering the anisotropic radiation pattern of a CCA, which cannot be separated from the manifold matrix, an improved interpolation method is investigated to transform the directional subarray into omnidirectional virtual nested arrays without non-orthogonal perturbation on the noise vector. Then, the cross-correlation matrix(CCM) of the subarrays is used to generate the consecutive co-arrays without redundant elements and eliminate the noise vector. Finally, the full-rank equivalent covariance matrix is constructed using the output of co-arrays,and the unitary estimation of the signal parameters via rotational invariance techniques(ESPRIT) is performed on the equivalent covariance matrix to estimate the DOAs with low computational complexity. Numerical simulations verify the superior performance of the proposed algorithm, especially under a low signal-to-noise ratio(SNR) environment. 展开更多
关键词 Direction of arrival(DOA) Conformal antenna array Interpolation technique Nested array
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Calyceal Diverticulum Mimicking Simple Parapelvic Cyst:a Case Report 被引量:2
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作者 Yong-han Peng Wei Zhang +1 位作者 xiao-feng gao Ying-hao Sun 《Chinese Medical Sciences Journal》 CAS CSCD 2015年第1期56-58,共3页
CALYCEAL diverticulum is a cystic intrarenal cavity lined by nonsecretory transitional epithelium that communicates with the collecting system via a narrow isthmus or infundibulum. It is arare anatomic anomaly with an... CALYCEAL diverticulum is a cystic intrarenal cavity lined by nonsecretory transitional epithelium that communicates with the collecting system via a narrow isthmus or infundibulum. It is arare anatomic anomaly with an incidence of 0.2% to 0.6% in the patients undergoing renal imaging.1 Single imaging modality usually cannot differentiate calyceal diverticulum from other cystic renal diseases.2 Here, we report a 60-year-old male who was reliably diagnosed with calyceal diverticulum by retrograde urography combined with non-enhanced computed tomography (CT) and magnetic resonance urography (MRU). 展开更多
关键词 calyceal diverticulum retrograde urography computed tomography magnetic resonance urography
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Approximation Designs for Energy Harvesting Relay Deployment in Wireless Sensor Networks
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作者 Yi Wang Yi-Xue Liu +2 位作者 Shun-Jia Zhu xiao-feng gao Chen Tian 《Journal of Computer Science & Technology》 SCIE EI CSCD 2022年第4期779-796,共18页
Energy harvesting technologies allow wireless devices to be recharged by the surrounding environment, providing wireless sensor networks (WSNs) with higher performance and longer lifetime. However, directly building a... Energy harvesting technologies allow wireless devices to be recharged by the surrounding environment, providing wireless sensor networks (WSNs) with higher performance and longer lifetime. However, directly building a wireless sensor network with energy harvesting nodes is very costly. A compromise is upgrading existing networks with energy harvesting technologies. In this paper, we focus on prolonging the lifetime of WSNs with the help of energy harvesting relays (EHRs). EHRs are responsible for forwarding data for sensor nodes, allowing them to become terminals and thus extending their lifetime. We aim to deploy a minimum number of relays covering the whole network. As EHRs have several special properties such as the energy harvesting and depletion rate, it brings great research challenges to seek an optimal deployment strategy. To this end, we propose an approximation algorithm named Effective Relay Deployment Algorithm, which can be divided into two phases: disk covering and connector insertion using the partitioning technique and the Steinerization technique, respectively. Based on probabilistic analysis, we further optimize the performance ratio of our algorithm to (5 + 6/K) where K is an integer denoting the side length of a cell after partitioning. Our extensive simulation results show that our algorithm can reduce the number of EHRs to be deployed by up to 45% compared with previous work and thus validate the efficiency and effectiveness of our solution. 展开更多
关键词 approximation algorithm constraint relay deployment energy harvesting wireless sensor network
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