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LoRa Backscatter Network Efficient Data Transmission Using RF Source Range Control
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作者 Dae-Young Kim SoYeon Lee Seokhoon Kim 《Computers, Materials & Continua》 SCIE EI 2023年第2期4015-4025,共11页
Networks based on backscatter communication provide wireless data transmission in the absence of a power source.A backscatter device receives a radio frequency(RF)source and creates a backscattered signal that deliver... Networks based on backscatter communication provide wireless data transmission in the absence of a power source.A backscatter device receives a radio frequency(RF)source and creates a backscattered signal that delivers data;this enables new services in battery-less domains with massive Internet-of-Things(IoT)devices.Connectivity is highly energy-efficient in the context of massive IoT applications.Outdoors,long-range(LoRa)backscattering facilitates large IoT services.A backscatter network guarantees timeslot-and contention-based transmission.Timeslot-based transmission ensures data transmission,but is not scalable to different numbers of transmission devices.If contention-based transmission is used,collisions are unavoidable.To reduce collisions and increase transmission efficiency,the number of devices transmitting data must be controlled.To control device activation,the RF source range can be modulated by adjusting the RF source power during LoRa backscatter.This reduces the number of transmitting devices,and thus collisions and retransmission,thereby improving transmission efficiency.We performed extensive simulations to evaluate the performance of our method. 展开更多
关键词 Backscatter communication LoRa backscatter RF source range control activated device control internet of things
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Dynamic analysis and split range control for maximization of operating range of continuous microbial fuel cell
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作者 Ashish Yewale Ravi Methekar Shailesh Agrawal 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2020年第9期2368-2381,共14页
Human development is inherently connected with availability of water and energy.Energy production requires water,whereas water treatment needs energy.On the other hand,microbial fuel cell has capability to produce ene... Human development is inherently connected with availability of water and energy.Energy production requires water,whereas water treatment needs energy.On the other hand,microbial fuel cell has capability to produce energy and water simultaneously from waste water or organic matter.In this paper,first principle-based model of variable volume microbial fuel cell is simulated.Hydraulic retention time is selected as the manipulated variable using the study of steady state and dynamic responses.Classical PI and model predictive control strategies are developed for controlling the produced power from the cell,and its performance is tested for servo problem.Settling time for positive and negative set points is found to be 126 and 889 h in case of classical PI and 120 and 750 h in case of linear MPC,respectively along with large increase(three times order of magnitude)in working volume for negative set point.These control challenges are overcome by using split range controller with variable and constant volume microbial fuel cells.The settling time for negative set point is found to be 49 and 21 h for classical PI and linear MPC schemes,respectively,which is significantly lower than using only variable volume microbial fuel cell.Also,there is no increase in the working volume of the constant volume microbial fuel cell.Hence,operating range of the microbial fuel cell is enhanced using split range controller. 展开更多
关键词 CMFC MODELING Variable Volume Split range Controller
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Progress on the use of satellite technology for gravity exploration
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作者 Ding Yanwei Ma Li +14 位作者 Xu Zhiming Li Ming Huo Hongqing Tan Shuping Gou Xingyu Wang Xudong Yang Fuquan Mao Wei Liu Yingna Zhong Xingwang Xi Dongxue Hu Lingyun Huang Lin Li Songming Zhang Xiaomin 《Geodesy and Geodynamics》 2015年第4期299-306,共8页
In this paper, the technological progress on Chinese gravity exploration satellites is presented. Novel features such as ultra-stable structure, high accurate thermal control, drag-free and attitude control, micro-thr... In this paper, the technological progress on Chinese gravity exploration satellites is presented. Novel features such as ultra-stable structure, high accurate thermal control, drag-free and attitude control, micro-thrusters, aerodynamic configuration, the ability to perform micro-vibration analyses, microwave ranging system and mass center trimmer are described. 展开更多
关键词 Ultra-stable structure Precision thermal control Drag-free Micro-thruster K-band ranging Aerodynamics Micro-vibration Gravity satellite
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Nyquist Stability Analysis and Capacitance Selection for DC Current Flow Controllers in Meshed Multi-terminal HVDC Grids 被引量:3
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作者 Puyu Wang Shihua Feng +2 位作者 Pengcheng Liu Ningqiang Jiang Xiao-Ping Zhang 《CSEE Journal of Power and Energy Systems》 SCIE CSCD 2021年第1期114-127,共14页
Controllability of DC current/power flow is essentialin multi-terminal HVDC (MTDC) grids, particularly for theMTDC grids in a meshed topology. In this paper, consideringmeshed MTDC (M2TDC) grids with the installation ... Controllability of DC current/power flow is essentialin multi-terminal HVDC (MTDC) grids, particularly for theMTDC grids in a meshed topology. In this paper, consideringmeshed MTDC (M2TDC) grids with the installation of twoline/multi-lineDC current flow controllers (CFCs), a small-signalmodel of the DC CFCs integrated M2TDC grids is derived,studying the impact of the power losses of the DC CFC andtheir influence on the analysis of energy exchanges. The systemstability analysis is analysed using the Nyquist diagram, which ismore suitable for analyzing complex nonlinear systems with morecompact and reliable indicators of stability in comparison withgain/phase margins shown in the Bode diagram. In addition, aselection method of the interconnected capacitor of the DC CFCis proposed under different operating conditions. The impact ofthe switching frequencies of the DC CFC on the control ranges ofthe DC current flows is analyzed. The effectiveness of the Nyquistanalysis and the capacitance selection method is verified bysimulation studies using PSCAD/EMTDC. The obtained control ranges of the DC CFC with different switching frequenciesand capacitances would be useful for practical engineeringapplications. 展开更多
关键词 Capacitance selection method control ranges DC current flow controller(CFC) meshed multi-terminal HVDC(M2TDC)grid Nyquist stability analysis small-signal modelling switching frequencies
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