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Zhao, Junhui,Rong, Ran,Oh, Chang-Heon,Seo, Jeongwook The Korea Institute of Information and Commucation 2014 Journal of information and communication convergen Vol.12 No.4
In this paper, we analyze the effect of the coherence bandwidth of wireless channels on leakage suppression methods for discrete Fourier transform (DFT)-based channel estimation in orthogonal frequency division multiplexing (OFDM) systems. Virtual carriers in an OFDM symbol cause orthogonality loss in DFT-based channel estimation, which is referred to as the leakage problem. In order to solve the leakage problem, optimal and suboptimal methods have already been proposed. However, according to our analysis, the performance of these methods highly depends on the coherence bandwidth of wireless channels. If some of the estimated channel frequency responses are placed outside the coherence bandwidth, a channel estimation error occurs and the entire performance worsens in spite of a high signal-to-noise ratio.
Distance Geometry-based Wireless Location Algorithms in Cellular Networks with NLOS Errors
( Junhui Zhao ),( Hao Zhang ),( Rong Ran ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.6
This paper presents two distance geometry-based algorithms for wireless location in cellular network systems―distance geometry filtering (DGF) and distance geometry constraint (DGC). With time-of-arrival range measurements, the DGF algorithm estimates the mobile station position by selecting a set of measurements with relatively small NLOS (non-line-of-sight) errors, and the DGC algorithm optimizes the measurements first and then estimates the position using those optimized measurements. Simulation results show that the proposed algorithms can mitigate the impact of NLOS errors and effectively improve the accuracy of wireless location.
Nai-long Zhao,Wei Zhe Wang,Junhui Zhang,Ying Zheng Liu 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.4
In this paper, an axisymmetric rotor of a 1000-MW ultra-supercritical steam turbine was modeled with the commercial finite-element software ABAQUS with inlet parameters of 35 Mpa and 600°C. The temperature and Mises stress distributions of the rotor during the start-up procedure were then analyzed. The fatigue damage was predicted by the strain-life–based Manson-Coffin equation and the Miner rule. The results demonstrated that the fatigue damage was mainly generated at the rotor surface. For the requirement of the half life time, the cyclic number almost reached 4000. Furthermore, optimization by extending the warm-up phase is proposed to eliminate strain fluctuations and further decrease fatigue damage. The results showed that the fatigue damage significantly decreased at four key locations. The fatigue life during the start-up phase was improved.
Huang Bao,He Yongqing,Li Shengwen,Wei Xiaoan,Liu Junhui,Shan Zhi,Huang Yue,Chen Jiang,Zhao Fengdong 생화학분자생물학회 2020 Experimental and molecular medicine Vol.52 No.-
Calcipressin-1, also known as regulator of calcineurin 1 (RCAN1), can specifically bind calcineurin at or near the calcineurin A catalytic domain and downregulate calcineurin activity. However, whether RCAN1 affects the hypoxic intervertebral disc (IVD) phenotype through the calcineurin/NFAT signaling pathway remains unclear. First, we confirmed the characteristics of the degenerative nucleus pulposus (NP) by H&E, safranin O/fast green and Alcian blue staining, and detected increased RCAN1 levels in the degenerative NP by immunohistochemistry. Then, we demonstrated that the protein level of RCAN1.4 was higher than that of RCAN1.1 and progressively elevated from the control group to the Pfirrmann grade V group. In vitro, both hypoxia (1% O2) and overexpression of HIF-1α reduced the protein level of RCAN1.4 in rat NP cells in a dose- and time-dependent manner. We further found that miRNA-124, through a nondegradative pathway (without the proteasome or lysosome), suppressed the expression of RCAN1.4. As expected, calcineurin in NP cells was activated and primarily promoted nuclear translocation of NFATc1 under hypoxia or RCAN1.4 siRNA transfection. Furthermore, SOX9, type II collagen and MMP13 were elevated under hypoxia, RCAN1.4 siRNA transfection or NFATc1 overexpression. Using chromatin immunoprecipitation (ChIP) and a luciferase reporter assay (with mutation), we clarified that NFATc1 increasingly bound the SOX9 promotor region (bp −367~−357). Interaction of HIF-1α and NFATc1 promoted MMP13 transcription. Finally, we found that FK506 reversed hypoxia-induced activation of the calcineurin/NFAT signaling pathway in NP cells and an ex vivo model. Together, these findings show that the RCAN1.4-calcineurin/ NFAT signaling pathway has a vital role in the hypoxic phenotype of NP cells. RCAN1.4 might be a therapeutic target for degenerative disc diseases.