Amplitude Phase Shift Keying(APSK)is more suitable for the nonlinear channels of Low Earth Orbit(LEO)satellite communication systems compared to Quadrature Amplitude Modulation(QAM).To tackle challenges posed by Direc...Amplitude Phase Shift Keying(APSK)is more suitable for the nonlinear channels of Low Earth Orbit(LEO)satellite communication systems compared to Quadrature Amplitude Modulation(QAM).To tackle challenges posed by Direct Current(DC)interference and high demodulation complexity,we propose an APSK demodulation algorithm based on K-means clustering.Initially,static DC components are calculated and removed from the received APSK signals.Subsequently,the estimated APSK constellation points serve as initial centers for K-means clustering.These centers are refined through the K-means process and act as theoretical APSK constellation points for the Max-Log-MAP demodulation algorithm,effectively eliminating residual DC.We then introduce a low-complexity APSK demodulation algorithm that utilizes the symmetry of constellation points along with the Euclidean distance between DC-eliminated signals and these constellation points to minimize the set of constellation points.Simulation results indicate that for 32-APSK,our proposed demodulation submodule reduces computational complexity to approximately one-third that of the Max-Log-MAP algorithm while improving Bit Error Rate(BER)performance by about 0.23 dB.Furthermore,end-to-end simulation experiments conducted within LEO satellite communication systems demonstrate that our approach not only maintains this complexity advantage but also enhances BER performance by approximately 1.1 dB.展开更多
This paper proposes an equivalent modeling method for photovoltaic(PV)power stations via a particle swarm optimization(PSO)K-means clustering(KMC)algorithm with passive filter parameter clustering to address the compl...This paper proposes an equivalent modeling method for photovoltaic(PV)power stations via a particle swarm optimization(PSO)K-means clustering(KMC)algorithm with passive filter parameter clustering to address the complexities,simulation time cost and convergence problems of detailed PV power station models.First,the amplitude–frequency curves of different filter parameters are analyzed.Based on the results,a grouping parameter set for characterizing the external filter characteristics is established.These parameters are further defined as clustering parameters.A single PV inverter model is then established as a prerequisite foundation.The proposed equivalent method combines the global search capability of PSO with the rapid convergence of KMC,effectively overcoming the tendency of KMC to become trapped in local optima.This approach enhances both clustering accuracy and numerical stability when determining equivalence for PV inverter units.Using the proposed clustering method,both a detailed PV power station model and an equivalent model are developed and compared.Simulation and hardwarein-loop(HIL)results based on the equivalent model verify that the equivalent method accurately represents the dynamic characteristics of PVpower stations and adapts well to different operating conditions.The proposed equivalent modeling method provides an effective analysis tool for future renewable energy integration research.展开更多
To address the issue of abnormal energy consumption fluctuations in the converter steelmaking process,an integrated diagnostic method combining the gray wolf optimization(GWO)algorithm,support vector machine(SVM),and ...To address the issue of abnormal energy consumption fluctuations in the converter steelmaking process,an integrated diagnostic method combining the gray wolf optimization(GWO)algorithm,support vector machine(SVM),and K-means clustering was proposed.Eight input parameters—derived from molten iron conditions and external factors—were selected as feature variables.A GWO-SVM model was developed to accurately predict the energy consumption of individual heats.Based on the prediction results,the mean absolute percentage error and maximum relative error of the test set were employed as criteria to identify heats with abnormal energy usage.For these heats,the K-means clustering algorithm was used to determine benchmark values of influencing factors from similar steel grades,enabling root-cause diagnosis of excessive energy consumption.The proposed method was applied to real production data from a converter in a steel plant.The analysis reveals that heat sample No.44 exhibits abnormal energy consumption,due to gas recovery being 1430.28 kg of standard coal below the benchmark level.A secondary contributing factor is a steam recovery shortfall of 237.99 kg of standard coal.This integrated approach offers a scientifically grounded tool for energy management in converter operations and provides valuable guidance for optimizing process parameters and enhancing energy efficiency.展开更多
针对传统微震震源定位方法在噪声干扰下鲁棒性不足的问题,提出一种融合遗传算法(genetic algorithm,GA)全局搜索和部落竞争与成员合作算法(competition of tribes and cooperation of members algorithm,CTCM)优化K-means聚类的微震震...针对传统微震震源定位方法在噪声干扰下鲁棒性不足的问题,提出一种融合遗传算法(genetic algorithm,GA)全局搜索和部落竞争与成员合作算法(competition of tribes and cooperation of members algorithm,CTCM)优化K-means聚类的微震震源稳健定位框架。首先,基于到时差数学模型构建不同测点四四组合的最优化目标函数,通过GA算法遍历求解这些以未知震源三维坐标为自变量的三元二次函数,生成大量震源近似解;然后,引入CTCM对K-means聚类的初始聚类中心进行优化,将聚类结果的误差平方和(sum of squared error,SSE)作为最优化目标函数的因变量,以状态转移相关矩阵提升高维数据的聚类稳定性;最后,执行优化后的K-means得到多个聚类中心,以这些中心坐标的中位数和各点马氏距离构建抗差定位策略,并应用中位数绝对偏差(median absolute deviation,MAD)实现对异常点的自动剔除,其他聚类中心的加权算术平均值即为最终解。结果表明,该方法(GA-CTCM-K-means)在1组平面型仿真实验和2组真实微震案例下均能实现较好的异常剔除和定位效能,定位精度分别可达9.5243 m、137.8651 m、28.1009 m,优于Geiger法、单纯形法、震源扫描法等传统方法,是一种具有一定应用价值的微震震源定位方案。展开更多
In the unmanned aerial vehicle(UAV)assisted edge computing system,the broadcast characteristics of the UAV signal,the high mobility of the UAV,and the limited airborne energy make the task offloading strategy face cha...In the unmanned aerial vehicle(UAV)assisted edge computing system,the broadcast characteristics of the UAV signal,the high mobility of the UAV,and the limited airborne energy make the task offloading strategy face challenges such as increased risk of information disclosure,limited computing resources,and the trade-off between energy consumption and flight time.To address these issues,we propose a K-means in-depth reinforcement learning algorithm based on Soft Actor-Critic(SAC).The proposed method first leverages the K-means clustering algorithm to determine the optimal deployment of ground jammers based on the final distribution of mobile users.Then,building upon the SAC framework,the Cross-Entropy Method(CEM)global sampling strategy is incorporated into the action output phase to form the K-SAC algorithm.This algorithm aims to maximize system rewards,which holistically balance task offloading delay,energy consumption,and secure offloading rate.Consequently,it jointly optimizes the optimal hovering positions of auxiliary UAVs and the task offloading ratio for each user,leading to an overall performance improvement in system security and efficiency.Finally,compared with current schemes,the system benefits achieved by the proposed scheme were 9.83%higher on average in different computing task sizes,13.67%higher on average in different task complexities,and 14.63%higher on average in different interference powers.展开更多
Various factors,including weak tie-lines into the electric power system(EPS)networks,can lead to low-frequency oscillations(LFOs),which are considered an instant,non-threatening situation,but slow-acting and poisonous...Various factors,including weak tie-lines into the electric power system(EPS)networks,can lead to low-frequency oscillations(LFOs),which are considered an instant,non-threatening situation,but slow-acting and poisonous.Considering the challenge mentioned,this article proposes a clustering-based machine learning(ML)framework to enhance the stability of EPS networks by suppressing LFOs through real-time tuning of key power system stabilizer(PSS)parameters.To validate the proposed strategy,two distinct EPS networks are selected:the single-machine infinite-bus(SMIB)with a single-stage PSS and the unified power flow controller(UPFC)coordinated SMIB with a double-stage PSS.To generate data under various loading conditions for both networks,an efficient but offline meta-heuristic algorithm,namely the grey wolf optimizer(GWO),is used,with the loading conditions as inputs and the key PSS parameters as outputs.The generated loading conditions are then clustered using the fuzzy k-means(FKM)clustering method.Finally,the group method of data handling(GMDH)and long short-term memory(LSTM)ML models are developed for clustered data to predict PSS key parameters in real time for any loading condition.A few well-known statistical performance indices(SPI)are considered for validation and robustness of the training and testing procedure of the developed FKM-GMDH and FKM-LSTM models based on the prediction of PSS parameters.The performance of the ML models is also evaluated using three stability indices(i.e.,minimum damping ratio,eigenvalues,and time-domain simulations)after optimally tuned PSS with real-time estimated parameters under changing operating conditions.Besides,the outputs of the offline(GWO-based)metaheuristic model,proposed real-time(FKM-GMDH and FKM-LSTM)machine learning models,and previously reported literature models are compared.According to the results,the proposed methodology outperforms the others in enhancing the stability of the selected EPS networks by damping out the observed unwanted LFOs under various loading conditions.展开更多
基金the Key Project of the Chongqing Natural Science Foundation(2022NSCQ-LZX0191)the Key Research Program of Science and Technology of the Chongqing Education Commission(KJZD-K202202402)+1 种基金the Scientific Research Start-up Fund of Chongqing University of Posts and Telecommunications(A2023-62)the Chongqing Natural Science Foundation(cstc2024ycjh-bgzxm003)for their invaluable support in this research。
摘要Amplitude Phase Shift Keying(APSK)is more suitable for the nonlinear channels of Low Earth Orbit(LEO)satellite communication systems compared to Quadrature Amplitude Modulation(QAM).To tackle challenges posed by Direct Current(DC)interference and high demodulation complexity,we propose an APSK demodulation algorithm based on K-means clustering.Initially,static DC components are calculated and removed from the received APSK signals.Subsequently,the estimated APSK constellation points serve as initial centers for K-means clustering.These centers are refined through the K-means process and act as theoretical APSK constellation points for the Max-Log-MAP demodulation algorithm,effectively eliminating residual DC.We then introduce a low-complexity APSK demodulation algorithm that utilizes the symmetry of constellation points along with the Euclidean distance between DC-eliminated signals and these constellation points to minimize the set of constellation points.Simulation results indicate that for 32-APSK,our proposed demodulation submodule reduces computational complexity to approximately one-third that of the Max-Log-MAP algorithm while improving Bit Error Rate(BER)performance by about 0.23 dB.Furthermore,end-to-end simulation experiments conducted within LEO satellite communication systems demonstrate that our approach not only maintains this complexity advantage but also enhances BER performance by approximately 1.1 dB.
基金supported by the Research Project of China Southern Power Grid(No.056200KK52222031).
摘要This paper proposes an equivalent modeling method for photovoltaic(PV)power stations via a particle swarm optimization(PSO)K-means clustering(KMC)algorithm with passive filter parameter clustering to address the complexities,simulation time cost and convergence problems of detailed PV power station models.First,the amplitude–frequency curves of different filter parameters are analyzed.Based on the results,a grouping parameter set for characterizing the external filter characteristics is established.These parameters are further defined as clustering parameters.A single PV inverter model is then established as a prerequisite foundation.The proposed equivalent method combines the global search capability of PSO with the rapid convergence of KMC,effectively overcoming the tendency of KMC to become trapped in local optima.This approach enhances both clustering accuracy and numerical stability when determining equivalence for PV inverter units.Using the proposed clustering method,both a detailed PV power station model and an equivalent model are developed and compared.Simulation and hardwarein-loop(HIL)results based on the equivalent model verify that the equivalent method accurately represents the dynamic characteristics of PVpower stations and adapts well to different operating conditions.The proposed equivalent modeling method provides an effective analysis tool for future renewable energy integration research.
基金support from the National Key R&D Program of China(Grant No.2020YFB1711100).
摘要To address the issue of abnormal energy consumption fluctuations in the converter steelmaking process,an integrated diagnostic method combining the gray wolf optimization(GWO)algorithm,support vector machine(SVM),and K-means clustering was proposed.Eight input parameters—derived from molten iron conditions and external factors—were selected as feature variables.A GWO-SVM model was developed to accurately predict the energy consumption of individual heats.Based on the prediction results,the mean absolute percentage error and maximum relative error of the test set were employed as criteria to identify heats with abnormal energy usage.For these heats,the K-means clustering algorithm was used to determine benchmark values of influencing factors from similar steel grades,enabling root-cause diagnosis of excessive energy consumption.The proposed method was applied to real production data from a converter in a steel plant.The analysis reveals that heat sample No.44 exhibits abnormal energy consumption,due to gas recovery being 1430.28 kg of standard coal below the benchmark level.A secondary contributing factor is a steam recovery shortfall of 237.99 kg of standard coal.This integrated approach offers a scientifically grounded tool for energy management in converter operations and provides valuable guidance for optimizing process parameters and enhancing energy efficiency.
摘要针对传统微震震源定位方法在噪声干扰下鲁棒性不足的问题,提出一种融合遗传算法(genetic algorithm,GA)全局搜索和部落竞争与成员合作算法(competition of tribes and cooperation of members algorithm,CTCM)优化K-means聚类的微震震源稳健定位框架。首先,基于到时差数学模型构建不同测点四四组合的最优化目标函数,通过GA算法遍历求解这些以未知震源三维坐标为自变量的三元二次函数,生成大量震源近似解;然后,引入CTCM对K-means聚类的初始聚类中心进行优化,将聚类结果的误差平方和(sum of squared error,SSE)作为最优化目标函数的因变量,以状态转移相关矩阵提升高维数据的聚类稳定性;最后,执行优化后的K-means得到多个聚类中心,以这些中心坐标的中位数和各点马氏距离构建抗差定位策略,并应用中位数绝对偏差(median absolute deviation,MAD)实现对异常点的自动剔除,其他聚类中心的加权算术平均值即为最终解。结果表明,该方法(GA-CTCM-K-means)在1组平面型仿真实验和2组真实微震案例下均能实现较好的异常剔除和定位效能,定位精度分别可达9.5243 m、137.8651 m、28.1009 m,优于Geiger法、单纯形法、震源扫描法等传统方法,是一种具有一定应用价值的微震震源定位方案。
基金supported by the Laibin City Scientific Research and Technology Development Program Project(No.241509)Guangxi Key Research and Development Program(AB24010237).
摘要In the unmanned aerial vehicle(UAV)assisted edge computing system,the broadcast characteristics of the UAV signal,the high mobility of the UAV,and the limited airborne energy make the task offloading strategy face challenges such as increased risk of information disclosure,limited computing resources,and the trade-off between energy consumption and flight time.To address these issues,we propose a K-means in-depth reinforcement learning algorithm based on Soft Actor-Critic(SAC).The proposed method first leverages the K-means clustering algorithm to determine the optimal deployment of ground jammers based on the final distribution of mobile users.Then,building upon the SAC framework,the Cross-Entropy Method(CEM)global sampling strategy is incorporated into the action output phase to form the K-SAC algorithm.This algorithm aims to maximize system rewards,which holistically balance task offloading delay,energy consumption,and secure offloading rate.Consequently,it jointly optimizes the optimal hovering positions of auxiliary UAVs and the task offloading ratio for each user,leading to an overall performance improvement in system security and efficiency.Finally,compared with current schemes,the system benefits achieved by the proposed scheme were 9.83%higher on average in different computing task sizes,13.67%higher on average in different task complexities,and 14.63%higher on average in different interference powers.
基金supported by the Deanship of Research at the King Fahd University of Petroleum&Minerals,Dhahran,31261,Saudi Arabia,under Project No.EC241001.
摘要Various factors,including weak tie-lines into the electric power system(EPS)networks,can lead to low-frequency oscillations(LFOs),which are considered an instant,non-threatening situation,but slow-acting and poisonous.Considering the challenge mentioned,this article proposes a clustering-based machine learning(ML)framework to enhance the stability of EPS networks by suppressing LFOs through real-time tuning of key power system stabilizer(PSS)parameters.To validate the proposed strategy,two distinct EPS networks are selected:the single-machine infinite-bus(SMIB)with a single-stage PSS and the unified power flow controller(UPFC)coordinated SMIB with a double-stage PSS.To generate data under various loading conditions for both networks,an efficient but offline meta-heuristic algorithm,namely the grey wolf optimizer(GWO),is used,with the loading conditions as inputs and the key PSS parameters as outputs.The generated loading conditions are then clustered using the fuzzy k-means(FKM)clustering method.Finally,the group method of data handling(GMDH)and long short-term memory(LSTM)ML models are developed for clustered data to predict PSS key parameters in real time for any loading condition.A few well-known statistical performance indices(SPI)are considered for validation and robustness of the training and testing procedure of the developed FKM-GMDH and FKM-LSTM models based on the prediction of PSS parameters.The performance of the ML models is also evaluated using three stability indices(i.e.,minimum damping ratio,eigenvalues,and time-domain simulations)after optimally tuned PSS with real-time estimated parameters under changing operating conditions.Besides,the outputs of the offline(GWO-based)metaheuristic model,proposed real-time(FKM-GMDH and FKM-LSTM)machine learning models,and previously reported literature models are compared.According to the results,the proposed methodology outperforms the others in enhancing the stability of the selected EPS networks by damping out the observed unwanted LFOs under various loading conditions.