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        Secrecy Spectrum and Secrecy Energy Efficiency in Massive MIMO Enabled HetNets

        ( Zhihao Zhong ),( Jianhua Peng ),( Kaizhi Huang ),( Lu Xia ),( Xiaohui Qi ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.2

        Security and resource-saving are both demands of the fifth generation (5G) wireless networks. In this paper, we study the secrecy spectrum efficiency (SSE) and secrecy energy efficiency (SEE) of a K-tier massive multiple-input multiple-output (MIMO) enabled heterogeneous cellular network (HetNet), in which artificial noise (AN) are employed for secrecy enhancement. Assuming (i) independent Poisson point process model for the locations of base stations (BSs) of each tier as well as that of eavesdroppers, (ii) zero-forcing precoding at the macrocell BSs (MBSs), and (iii) maximum average received power-based cell selection, the tractable lower bound expressions for SSE and SEE of massive MIMO enabled HetNets are derived. Then, the influences on secrecy oriented spectrum and energy efficiency performance caused by the power allocation for AN, transmit antenna number, number of users served by each MBS, and eavesdropper density are analyzed respectively. Moreover, the analysis accuracy is verified by Monte Carlo simulations.

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        Multiphysics Modeling of Thermal Behavior of Commercial Pure Titanium Powder During Selective Laser Melting

        Wenlin Ye,Jin Bao,Jie Lei,Yicheng Huang,Zhihao Li,Peisheng Li,Ying Zhang 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.1

        A mesoscopic simulation based on random packing powder bed model was established to study the heat behavior of CP-Tiduring selective laser melting. The characteristics of the molten pool under the interaction of laser and powder, and theinfuence of laser power on the thermal behavior, hydrodynamics and surface morphology evolution of the molten pool werestudied. The results show that with the increase of laser power, the maximum temperature, temperature change rate, lifetimeof molten pool and size are greatly improved. In addition, the characteristics and heat behavior of the molten pool under thedouble track are mainly studied in this study. It is found that the maximum temperature, lifetime, and the length and width ofthe molten pool of the second track are higher than those in the frst, and with the increase of laser power, the length widthratio of the second track in molten pool becomes larger

      • KCI등재

        Multilevel Pedicle Subtraction Osteotomy for Correction of Thoracolumbar Kyphosis in Ankylosing Spondylitis: Clinical Effect and Biomechanical Evaluation

        Xin Lv,Yelidana Nuertai,Qiwei Wang,Di Zhang,Xumin Hu,Jiabao Liu,Ziliang Zeng,Renyuan Huang,Zhihao Huang,Qiancheng Zhao,Wenpeng Li,Zhilei Zhang,Liangbin Gao 대한척추신경외과학회 2024 Neurospine Vol.21 No.1

        Objective: To compare the clinical outcomes and biomechanical characteristics of 1-, 2-, and 3-level pedicle subtraction osteotomy (PSO), and establish selection criteria based on preoperative radiographic parameters. Methods: Patients undergone PSO to treat ankylosing spondylitis from February 2009 to May 2019 in Sun Yat-sen Memorial Hospital of Sun Yat-sen University were enrolled. According to the quantity of osteotomy performed, the participants were divided into group A (1-level PSO, n = 24), group B (2-level PSO, n = 19), and group C (3-level PSO, n = 11). Clinical outcomes were assessed before surgery and at the final follow-up. Comparisons of the radiographic parameters and quality-of-life indicators were performed among and within these groups, and the selection criteria were established by regression. Finite element analysis was conducted to compare the biomechanical characteristics of the spine treated with different quantity of osteotomies under different working conditions. Results: Three-level PSO improved the sagittal parameters more significantly, but resulted in longer operative time and greater blood loss (p < 0.05). Greater stress was found in the proximal screws and proximal junction area of the vertebra in the model simulating 1-level PSO. Larger stress of screws and vertebra was observed at the distal end in the model simulating 3-level PSO. Conclusion: Multilevel PSO works better for larger deformity correction than single-level PSO by allowing greater sagittal parameter correction and obtaining a better distribution of stress in the hardware construct, although with longer operation time and greater blood loss. Three-level osteotomy is recommended for the patients with preoperative of global kyphosis > 85.95°, T1 pelvic angle > 62.3°, sagittal vertical alignment > 299.55 mm, and pelvic tilt+ chin-brow vertical angle > 109.6°.

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