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( Xiaorong Xu ),( Andi Hu ),( Yingbiao Yao ),( Wei Feng ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.1
In an underlay cognitive simultaneous wireless information and power transfer (SWIPT) network, communication from secondary user (SU) to secondary destination (SD) is accomplished with decode-and-forward (DF) relays. Multiple energy-constrained relays are assumed to harvest energy from SU via power splitting (PS) protocol and complete SU secure information transmission with beamforming. Hence, physical layer security (PLS) is investigated in cognitive SWIPT network. In order to interfere with eavesdropper and improve relay’s energy efficiency, a destination-assisted jamming scheme is proposed. Namely, SD transmits artificial noise (AN) to interfere with eavesdropping, while jamming signal can also provide harvested energy to relays. Beamforming vector and power splitting ratio are jointly optimized with the objective of SU secrecy capacity maximization. We solve this non-convex optimization problem via a general two-stage procedure. Firstly, we obtain the optimal beamforming vector through semi-definite relaxation (SDR) method with a fixed power splitting ratio. Secondly, the best power splitting ratio can be obtained by one-dimensional search. We provide simulation results to verify the proposed solution. Simulation results show that the scheme achieves the maximum SD secrecy rate with appropriate selection of power splitting ratio, and the proposed scheme guarantees security in cognitive SWIPT networks.
( Xiaorong Xu ),( Liang Li ),( Yingbiao Yao ),( Xianyang Jiang ),( Sanqing Hu ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.11
Considering the tradeoff between energy consumption and outage behavior in buffer-aided relay selection, a novel energy-efficient buffer-aided optimal relay selection scheme with power adaptation and Inter-Relay Interference (IRI) cancellation is proposed. In the proposed scheme, energy consumption minimization is the objective with the consideration of relay buffer state, outage probability and relay power control, in order to eliminate IRI. The proposed scheme selects a pair of optimal relays from multiple candidate relays, denoted as optimal receive relay and optimal transmit relay respectively. Source-relay and relay-destination communications can be performed within a time-slot, which performs as Full-Duplex (FD) relaying. Markov chain model is applied to analyze the evolution of relay buffer states. System steady state outage probability and achievable diversity order are derived respectively. In addition, packet transmission delay and power reduction performance are investigated with a specific analysis. Numerical results show that the proposed scheme outperforms other relay selection schemes in terms of outage behavior with power adaptation and IRI cancellation in the same relay number and buffer size scenario. Compared with Buffer State relay selection method, the proposed scheme reduces transmission delay significantly with the same amount of relays. Average transmit power reduction can be implemented to relays with the increasing of relay number and buffer size, which realizes the tradeoff between energy-efficiency, outage behavior and delay performance in green cooperative communications.
Joint Subcarrier and Bit Allocation for Secondary User with Primary Users` Cooperation
( Xiaorong Xu ),( Yu-dong Yao ),( Sanqing Hu ),( Yingbiao Yao ) 한국인터넷정보학회 2013 KSII Transactions on Internet and Information Syst Vol.7 No.12
Interference between primary user (PU) and secondary user (SU) transceivers should be mitigated in order to implement underlay spectrum sharing in cognitive radio networks (CRN). Considering this scenario, an improved joint subcarrier and bit allocation scheme for cognitive user with primary users` cooperation (PU Coop) in CRN is proposed. In this scheme, the optimization problem is formulated to minimize the average interference power level at the PU receiver via PU Coop, which guarantees a higher primary signal to interference plus noise ratio (SINR) while maintaining the secondary user total rate constraint. The joint optimal scheme is separated into subcarrier allocation and bit assignment in each subcarrier via arith-metric geo-metric (AM-GM) inequality with asymptotical optimization solution. Moreover, the joint subcarrier and bit optimization scheme, which is evaluated by the available SU subcarriers and the allocated bits, is analyzed in the proposed PU Coop model. The performance of cognitive spectral efficiency and the average interference power level are investigated. Numerical analysis indicates that the SU`s spectral efficiency increases significantly compared with the PU non-cooperation scenario. Moreover, the interference power level decreases dramatically for the proposed scheme compared with the traditional Hughes-Hartogs bit allocation scheme.
Xiaorong Yu,Rui Zhang,Cunsheng Wei,Yuanyuan Gao,Yanhua Yu,Lin Wang,Junying Jiang,Xuemei Zhang,Junrong Li,Xuemei Chen 한국통합생물학회 2021 Animal cells and systems Vol.25 No.2
Monocarboxylate transporter 2 (MCT2) is the predominant monocarboxylate transporter expressed by neurons. MCT2 plays an important role in brain energy metabolism. Stroke survivors are at high risk of cognitive impairment. We reported previously that stroke-induced cognitive impairment was related to impaired energy metabolism. In the present study, we report that cognitive function was impaired after stroke in rats. We found that MCT2 expression, but not that of MCT1 or MCT4, was markedly decreased in the rat hippocampus at 7 and 28 days after transient middle cerebral artery occlusion (tMCAO). Moreover, MCT2 overexpression promoted recovery of cognitive function after stroke. The molecular mechanism underlying these effects may be related to an increase in adenosine monophosphate-activated protein kinase-mediated mitochondrial biogenesis induced by overexpression of MCT2. Our findings suggest that MCT2 activation ameliorates cognitive impairment after stroke.
Bidirectional Link Resource Allocation Strategy in GFDM-based Multiuser SWIPT Systems
( Xiaorong Xu ),( Minghang Sun ),( Wei-ping Zhu ),( Wei Feng ),( Yingbiao Yao ) 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.1
In order to enhance system energy efficiency, bidirectional link resource allocation strategy in GFDM-based multiuser SWIPT systems is proposed. In the downlink channel, each SWIPT user applies power splitting (PS) receiver structure in information decoding (ID) and non-linear energy harvesting (EH). In the uplink channel, information transmission power is originated from the harvested energy. An optimization problem is constructed to maximize weighted sum ID achievable rates in the downlink and uplink channels via bidirectional link power allocation as well as subcarriers and subsymbols scheduling. To solve this non-convex optimization problem, Lagrange duality method, sub-gradient-based method and greedy algorithm are adopted respectively. Simulation results show that the proposed strategy is superior to the fixed subcarrier scheme regardless of the weighting coefficients. It is superior to the heuristic algorithm in larger weighting coefficients scenario.
MoS2/Au-Sensitized TiO2 Nanotube Arrays with Core–Shell Nanostructure for Hydrogen Production
Xiaorong Cheng,Yuhua Lu,Shoulin Gu,Graham Dawson 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.9
Herein, a TiO2 NTAs-Au-MoS2 core–shell photoanode was constructed with the intention to fulfill the efficient transfer of photo-generated carriers to the photoelectrode's surface. Au nanoparticles were decorated by a drop casting method, and the MoS2 layer was deposited above the Au nanoparticles using a photoreduction-annealing process. Au nanoparticles were well dispersed on the inner wall of the TiO2 nanotubes and covered by the MoS2 layer, forming a core–shell nanostructure. The MoS2 layer significantly improved the attachment between Au nanoparticles and TiO2 NTAs, resulting in increased PEC stability and performance. Attributed to the excitation of Au nanoparticles' localized surface plasmon resonance effect and visible light utilization of MoS2, the TiO2 NTAs-Au-MoS2 core–shell photoanode exhibits greatly enhanced photocurrent density. An increase from 67 μA/cm2 to 234 μA/cm2 under Xe lamp illumination and from 2.6 μA/cm2 to 12.6 μA/cm2 under visible light illumination ( λ > 420 nm) compared with the TiO2 NTAs was observed.
Xiaorong Ding,Yuan-Ting Zhang 대한의용생체공학회 2019 Biomedical Engineering Letters (BMEL) Vol.9 No.1
Cuffl ess technique holds great promise to measure blood pressure (BP) in an unobtrusive way, improving diagnostics andmonitoring of hypertension and its related cardiovascular diseases, and maximizing the independence and participation ofindividual. Pulse transit time (PTT) has been the most commonly employed techniques for cuffl ess BP estimation. Manystudies have been conducted to explore its feasibility and validate its performance in the clinical settings. However, there isstill issues and challenges ahead before its wide application. This review will investigate the understanding and developmentof the PTT technique in depth, with a focus on the physiological regulation of arterial BP, the relationship between PTT andBP, and the summaries of the PTT-based models for BP estimation.
The functionalities and applications of whey/whey protein in fermented foods: a review
Xiaorong Zeng,Yujie Wang,Shuda Yang,Yijun Liu,Xing Li,Diru Liu 한국식품과학회 2024 Food Science and Biotechnology Vol.33 No.4
Whey, a major by-product of cheese production, is primarily composed of whey protein (WP). To mitigate environmental pollution, it is crucial to identify effective approaches for fully utilizing the functional components of whey or WP to produce high-value-added products. This review aims to illustrate the active substances with immunomodulatory, metabolic syndrome-regulating, antioxidant, antibacterial, and anti-inflammatory activities produced by whey or WP through fermentation processes, and summarizes the application and the effects of whey or WP on nutritional properties and health promotion in fermented foods. All these findings indicate that whey or WP can serve as a preservative, a source of high-protein dietary, and a source of physiologically active substance in the production of fermented foods. Therefore, expanding the use of whey or WP in fermented foods is of great importance for converting whey into value-added products, as well as reducing whey waste and potential contamination.