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Optimal Relay Selection and Power Allocation in Cooperative Cognitive Communication System
Guanglong Yang,Xiao Wang,Xuezhi Tan 보안공학연구지원센터 2014 International Journal of Future Generation Communi Vol.7 No.6
This paper focuses on the optimal relay selection and power allocation issue, which studies the communication between SS (Secondary Source) and two SDs (Secondary Destinations) through single relay in CR (cooperative cognitive communication) system. Sufficiently takes the multi-antenna relay, primary-secondary users coexisting, and AF (Amplify and Forward) relay mode as the researching background, and takes the constraints caused by the primary user’s interference and the max transmission power into account, the author proposes to maximize the system throughput by the selection of cooperative relay and the allocation of optimal power. Furthermore, the author also puts forward the approximate expressions of the optimal power allocation, and figures out the optimal solution by the Lagrange multiplier, whose property can be manifested by the simulation and comparison results.
Temporal Variation of Intertidal Seagrass in Southern China (2008–2014)
Guanglong Qiu,Frederick T. Short,Hangqing Fan,Guohua Liu 한국해양과학기술원 2017 Ocean science journal Vol.52 No.3
Understanding the temporal dynamics of seagrasses and the major influences on seagrass growth is critical for seagrass habitat conservation and administration. However, little work has been done regarding these issues in southern China. To examine inter-annual and seasonal variations of the intertidal Halophila ovalis community in southern China, we conducted quarterly sampling using the SeagrassNet methodology and assessed environmental conditions as well as direct anthropogenic impacts on the seagrass meadow from July 2008 to October 2014. Our study demonstrated strong inter-annual and seasonal dynamics of the intertidal seagrass meadow in the study area. Generally, the community performed best (highest seagrass cover, leaf area, shoot density, total biomass) in summer and worst in spring among the 4 seasons. The temporal variations in the seagrass community attributes (e.g. above-ground biomass) were significantly affected by precipitation, atmospheric visibility, and salinity, while leaf width was significantly negatively correlated with temperature, atmospheric visibility and salinity. Temperature was a major factor influencing the seagrass community (both macroalgae and seagrass), with temperature data showing an inverse relationship between seagrass and macroalgae. The above-ground: below-ground biomass ratio and leaf width of H. ovalis were the most sensitive plant parameters monitored when assessing environmental interactions. Human physical disturbances did not have a significant effect on seagrass dynamics in the study area. We concluded that long-term monitoring (like SeagrassNet) is valuable in understanding the relationship between environmental variables and seagrasses.
Guanglong Yang,Xiao Wang,Xuezhi Tan 보안공학연구지원센터 2014 International Journal of Control and Automation Vol.7 No.11
Conventional distributed power control algorithms in cognitive radio (CR) are based on the assumption of perfect channel state information (CSI) which may lead to performance degradation in practical systems. In this paper, the robust distributed power control problem is investigated in CR systems by considering the uncertainty of channel gain. The objective is to maximize the sum rate of secondary users (SUs) subject to the primary users (PUs) interference power constraints and the transmission power constraint of SUs. The channel gain fluctuation is described using ellipsoid sets and the interference power constraints can be converted into robust interference power constraints. Lagrangian duality method is applied to solve the robust power control problem in a distributed way. Simulation results show that the effectiveness of the proposed robust algorithm.
Synthesis of Hydroxylactams and Esters Derived from Thalidomide and Their Antitumor Activities
Guanglong Sun,Xiangchao Liu,Heng Zhou,Zenglu Liu,Zhenmin Mao 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.5
A novel and convenient route for the synthesis of a series of thalidomide derivatives is described. Compound 2 was cyclized with different amines under alkaline condition to obtain 4-nitro substituted phthalimidines 3a-d. Hydroxylactams 4a-d were produced via bromination and hydroxylation. Different acyl chlorides were reacted with hydroxylactams to provide the desired esters 5a-d. All compounds were evaluated by MTT assay for their inhibitory activities against HCT-116, MG-63, MCF-7, HUVEC and HMVEC cell lines in vitro. Most of them showed no obvious cytotoxic effect on normal human cells, compounds 4a-d, 5a2, 5a4, 5a5, 5b2, 5c2 and 5d2 exhibited potent antitumor activities, among which compounds 5a2 and 5b2 were more effective than 5-FU.
Power Control for Cognitive Radio Networks under Imperfect CSI Based on Game Theory
Guanglong Yang,Xiao Wang,Xuezhi Tan 보안공학연구지원센터 2014 International Journal of Control and Automation Vol.7 No.12
In this paper, the problem of power control for cognitive systems is studied via game theory. The objective is to maximize the sum utility of secondary users (SUs) subject to the primary users (PUs) interference constraints, the transmission power constraints of SUs, and the signal-to-interference-plus-noise ratio (SINR) constraint of each SU. In our earlier work, the problem was formulated as a non-cooperative game under the assumption of perfect channel state information (CSI). Nash equilibrium (NE) is considered as the solution of this game. A distributed algorithm is proposed which can converge to the NE. Due to the limited cooperation between the secondary base station (SBS) and the PU, imperfect CSI between the SBS and the PU is further considered in this work. The problem is formulated as a robust game. As it is difficult to solve the optimization problem in this case, existence of the NE cannot be analyzed. Therefore, convergence property of the sum utility of SUs will be illustrated numerically. Simulation results show that under imperfect CSI the proposed approach can converge to a locally optimal transmission power level, while the sum utility of SUs converges with the increase of the transmission power constraint of SUs.
Synthesis of Hydroxylactams and Esters Derived from Thalidomide and Their Antitumor Activities
Sun, Guanglong,Liu, Xiangchao,Zhou, Heng,Liu, Zenglu,Mao, Zhenmin Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.5
A novel and convenient route for the synthesis of a series of thalidomide derivatives is described. Compound 2 was cyclized with different amines under alkaline condition to obtain 4-nitro substituted phthalimidines 3a-d. Hydroxylactams 4a-d were produced via bromination and hydroxylation. Different acyl chlorides were reacted with hydroxylactams to provide the desired esters 5a-d. All compounds were evaluated by MTT assay for their inhibitory activities against HCT-116, MG-63, MCF-7, HUVEC and HMVEC cell lines in vitro. Most of them showed no obvious cytotoxic effect on normal human cells, compounds 4a-d, $5a_2$, $5a_4$, $5a_5$, $5b_2$, $5c_2$ and $5d_2$ exhibited potent antitumor activities, among which compounds $5a_2$ and $5b_2$ were more effective than 5-FU.