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Learning to Optimize for Resource Allocation in LTE-U Networks

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China Communications 2021年第3期18卷 142-154页

作者： Guanhua Chai Weihua Wu Qinghai Yang runzi liu Kyung Sup Kwak School of Telecommunications Engineering Xidian UniversityXi’an710071ShaanxiChina School of Information and Control Engineering Xian University of Architecture and TechnologyXi’an710055ShaanxiChina School of Information Technology and Telecommunications Inha University#253 Yonghyun-dongNam-guIncheon402-751 Korea

This paper proposes a deep learning(DL)resource allocation framework to achieve the harmonious coexistence between the transceiver pairs(TPs)and the Wi-Fi users in LTE-U networks.The nonconvex resource allocation is considered as a constrained learning problem and the deep neural network(DNN)is employed to approximate the optimal resource allocation decisions through unsupervised manner.A parallel DNN framework is proposed to deal with the two optimization variables in this problem,where one is the licensed power allocation unit and the other is the unlicensed time fraction occupied unit.Besides,to guarantee the feasibility of the proposed algorithm,the Lagrange dual method is used to relax the constraints into the DNN training process.Then,the dual variable and the DNN parameter are alternating update via the batch-based gradient decent method until the training process converges.Numerical results show that the proposed algorithm is feasible and has better performance than other general algorithms.

关键词： deep learning resource allocation LTE-U networks Wi-Fi system

Utilization and Analysis of Resource Mobility in Space Information Networks

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Journal of Communications and Information Networks 2019年第1期4卷 67-77页

作者： Yiting Zhu runzi liu Min Sheng Liqin Yang Jiandong Li Weihua Wu Jianping liu The State Key Laboratory of ISN Xidian UniversityXi’anShaanxi 710071China The State Key Lab of Astronautics Dynamics Xi’an Satellite Control CentreXi’anShaanxi 710043China

In space information networks,resource mobility is an important factor affecting the network performance,which not only results in challenges in resource management but also brings opportunities to the improvement of network service capability.In order to explore the restriction and improvement mechanism of resource mobility on network performance,we firstly use the time-expanded resource relationship graph to represent the moving behavior of multidimensional resources and the collaborative relationship between different resources.Then by jointly considering the number of disjoint resource combinations,the length of moving time window,and the parameter of resource independence,we propose(k,n,L)degree of freedom on resource combination as a metric measuring performance gain resulted from resource mobility.Furthermore,the analysis of resource mobility is transformed into the problem of finding disjoint paths in the graph,and the tradeoff relationship between QoS requirements of task and resource mobility utilization is discussed.Finally,the tradeoff between the gain of resource mobility utilization and the payment of service process delay is revealed through simulation.

关键词： space information networks resource mo-bility degree of freedom on resource combination

Resource Mobility Aware Hybrid Task Planning in Space Information Networks

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Journal of Communications and Information Networks 2019年第4期4卷 107-116页

作者： runzi liu Yiting Zhu Yan Zhang Weihua Wu Di Zhou Kai Chi School of Information and Control Engineering Xi’an University of Architecture and TechnologyXi’anShaanxi 710055China The State Key Lab of ISN Xidian UniversityXi’anShaanxi 710071China Science and Technology on Communication Networks Laboratory CETC the 54th research instituteShijiazhuangHebei 050081China Electric Information Network Laboratory CETC the 20th research instituteXi’anShaanxi 710068China

In this paper,a resource mobility aware two-stage hybrid task planning algorithm is proposed to reduce the resource conflict between emergency tasks and the common tasks,so as to improve the overall performance of space information networks.Specifically,in the common task planning stage,a resource fragment avoidance task planning algorithm is proposed,which reduces the contention between emergency tasks and the planned common tasks in the next stage by avoiding the generation of resource fragments.For emergency tasks,we design a metric to quantify the revenue of the candidate resource combination of emergency tasks,which considers both the priority of the tasks and the impact on the planned common tasks.Based on this,a resource mobility aware emergency task planning algorithm is proposed,which strikes a good balance between improving the sum priority and avoiding disturbing the planned common tasks.Finally,simulation results show that the proposed algorithm is superior to the existing algorithms in both the sum task priority and the task completion rate.

关键词： space information network task planning resource mobility

基于分层强化学习的中继卫星网络任务动态调度方法

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通信学报 2023年第7期44卷 207-217页

作者：刘润滋马天赐吴伟华要趁红杨清海西安建筑科技大学信息与控制工程学院陕西西安710399 陕西师范大学物理学与信息技术学院陕西西安710119 西安电子科技大学通信工程学院陕西西安710071

近年来,随着各类紧急任务数量的不断增长,如何在控制对常规任务影响的同时保障系统的收益已成为中继卫星网络任务动态调度的巨大挑战。针对这一问题,以最大化紧急任务总收益和最小化常规任务破坏程度为目标,提出了一种基于分层强化学习... 详细信息

近年来,随着各类紧急任务数量的不断增长,如何在控制对常规任务影响的同时保障系统的收益已成为中继卫星网络任务动态调度的巨大挑战。针对这一问题,以最大化紧急任务总收益和最小化常规任务破坏程度为目标,提出了一种基于分层强化学习的中继卫星网络任务动态调度方法。具体而言,为了兼顾系统的长期与短期性能,设计了由上、下级DQN实现的双层调度框架,上级DQN从长期性能出发决定临时优化目标,下级DQN根据优化目标决定当前任务的调度策略。仿真结果表明,与传统的深度学习方法以及部分处理动态调度问题的启发式方法相比,所提方法能够在降低常规任务破坏程度的同时提升紧急任务总收益。

关键词：中继卫星网络任务调度深度强化学习多目标优化动态调度

Effectiveness and safety of acupuncture in treatment of pregnancyrelated symptoms:a systematic review and Meta-analysis

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Journal of Traditional Chinese Medicine 2024年第1期44卷 16-26页

作者： liu Tingting liu Tongou liu Mingfu School of Traditional Chinese Medicine Clinical Medicine Hubei University of Traditional Chinese MedicineWuhan 430000China First Clinical College of Hubei University of Traditional Chinese Medicine Wuhan 430000China Department of Acupuncture and Tuina Affiliated Hospital of Hubei University of Traditional Chinese MedicineHubei Provincial Hospital of Traditional Chinese MedicineWuhan 430000China

OBJECTIVE:To systematically evaluate the efficacy and safety of acupuncture(AM)in the treatment of pregnancyrelated symptoms such as acute vomiting during pregnancy.METHODS:We comprehensively searched the available literature up to November 2021,including Pub Med,Embase,Cochrane Library,Chinese Biomedical Literature Database,and China National Knowledge Infrastructure Database,for randomized controlled trials(RCTs)on AM for the treatment of severe vomiting,insomnia,pharyngeal and pelvic pain,mood abnormalities,and dyspepsia during pregnancy.RESULTS:Sixteen RCTs with a cumulative sample size of 1178 cases were included.Of these,964 patients were included in the Meta-analysis.The Meta-analysis results showed that AM was more efficient than Western medicine in treating discomfort during pregnancy[odds ratio(OR)=1.19,95%confidence interval(CI)(1.11,1.28),P<0.01].AM was better than the control group in improving the visual analog scale scores[standard mean difference(SMD)=0.62,95%CI(0.53,0.71),P<0.01].AM was superior to the control group in improving Numerical Rating Scale(NRS)symptom scores[OR=7.31,95%CI(3.36,15.94),P<0.01].There was no significant difference in adverse effects between the AM and sham-AM groups and the analgesic drug group[OR=0.70,95%CI(0.39,1.28),P=0.25],but the treatment and control groups had mild adverse effects with a low incidence.CONCLUSIONS:AM is more effective than other treatments or pharmacotherapy alone in the treatment of pregnancy-related symptoms,and is relatively safe.However,the quality of the included trials was rather poor,and high-quality studies are required to confirm our findings.

关键词： acupuncture pregnancy nausea vomiting sleep initiation and maintenance disorders low back pain pelvic pain mood abnormalities Meta-analysis systematic review

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卫星网络测控资源鲁棒调度方法

天地一体化信息网络 2023年第1期4卷 23-30页

作者：纪翔刘润滋要趁红陈剑豪慕桃西安建筑科技大学信息与控制工程学院陕西西安710055

卫星网络规模的持续增长为测控资源的有效调度带来了巨大挑战。受到天气等因素的影响,星地链路性能具有较强的不确定性。为了兼顾资源利用率与任务可靠性,提出一种鲁棒的测控资源调度方法。该方法可基于预测得到的星地链路信道状态分布... 详细信息

卫星网络规模的持续增长为测控资源的有效调度带来了巨大挑战。受到天气等因素的影响,星地链路性能具有较强的不确定性。为了兼顾资源利用率与任务可靠性,提出一种鲁棒的测控资源调度方法。该方法可基于预测得到的星地链路信道状态分布与规划周期内的任务分布情况为测控任务安排传输窗口的开始时间与持续时长,并通过反向迭代的方式对资源分配方案进行优化从而最大化任务期望收益值。实验结果表明,与传统的非鲁棒调度方法相比,所提调度方法在不同信道分布下都能取得良好的任务收益,实现资源利用率与任务可靠性的有效提高。

关键词：航天测控资源调度鲁棒调度卫星网络

Removal of Cr(Ⅵ)by glutaraldehyde-crosslinked chitosan encapsulating microscale zero-valent iron:Synthesis,mechanism,and longevity

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Journal of Environmental Sciences 2024年第8期142卷 115-128页

作者： Yijun Duan Fang liu Xiang liu Miao Li School of Environment Tsinghua UniversityBeijing 100084China Transportation Institute of Inner Mongolia University Hohhot 010070China

Microscale zero-valent iron(mZVI)has shown great potential for groundwater Cr(Ⅵ)remediation.However,low Cr(Ⅵ)removal capacity caused by passivation restricted the wide use of mZVI.We prepared mZVI/GCS by encapsulating mZVI in a porous glutaraldehydecrosslinked chitosan matrix,and the formation of the passivation layer was alleviated by reducing the contact between zero-valent iron particles.The average pore diameter of mZVI/GCS was 8.775 nm,which confirmed the mesoporous characteristic of this material.Results of batch experiments demonstrated that mZVI/GCS exhibited high Cr(Ⅵ)removal efficiency in a wide range of pH(2-10)and temperature(5-35℃).Common groundwater coexisting ions slightly affected m ZVI/GCS.The material showed great reusability,and the average Cr(Ⅵ)removal efficiency was 90.41%during eight cycles.In this study,we also conducted kinetics and isotherms analysis.Pseudo-second-order model was the most matched kinetics model.The Cr(Ⅵ)adsorption process was fitted by both Langmuir and Freundlich isotherms models,and the maximum Langmuir adsorption capacity of m ZVI/GCS reached243.63 mg/g,which is higher than the adsorption capacities of materials reported in most of the previous studies.Notably,the column capacity for Cr(Ⅵ)removal of a mZVI/GCS-packed column was 6.4 times higher than that of a mZVI-packed column in a 50-day experiment.Therefore,mZVI/GCS with a porous structure effectively relieved passivation problems of mZVI and showed practical application prospects as groundwater Cr(Ⅵ)remediation material with practical application prospects.

关键词： Chitosan Glutaraldehyde mZVI Cr(Ⅵ) Groundwater

Frequency Regulation of VSC-MTDC System with Offshore Wind Farms

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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 275-286页

作者： Haoyu liu Chongru liu North China Electric Power University Beijing 102206China

Frequency regulation of voltage source converter-based multi-terminal high-voltage direct current(VSC-MTDC)system with offshore wind farms enhances the frequency stability by compensating the power for a disturbed AC system.However,it is difficult to reasonably allocate frequency-regulation resources due to a lack of coordination mechanisms between wind farms and the MTDC system.Moreover,it is difficult for the frequency control of the wind farms to manage changes in wind speed;and the risk of wind-turbine stalls is high.Thus,based on the kinetic energy of wind turbines and the power margin of the converters,the frequency-regulation capability of wind turbines is evaluated,and a dynamic frequency-support scheme considering the real-time frequency-support capability of the wind turbines and system frequency evolution is proposed to improve the frequency-support performance.A power adaptation technique at variable wind speeds is developed;the active power in the frequency-support stage and restoration stage is switched according to the wind speed.A hierarchical zoning frequency-regulation scheme is designed to use the frequency-regulation resources of different links in the MTDC system with wind farms.The simulation results show that the novel frequency-regulation strategy maintains frequency stability with wind-speed changes and avoids multiple frequency dips.

关键词： Wind generation voltage source converter-based multi-terminal high-voltage direct current(VSC-MTDC) frequency regulation cooperative control adaptive control variable wind speed

Characteristics and sources of peroxyacetyl nitrate(PAN)in the rural North China Plain:Results from1-year continuous observations

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Journal of Environmental Sciences 2024年第4期138卷 719-731页

作者： Xin liu Xiaowei He Chenglong Zhang Yifei Song Shuyang Xie Chengtang liu Pengfei liu Yuanyuan Zhang Yujing Mu Junfeng liu Research Center for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China

Peroxyacetyl nitrate(PAN)is an important photochemical pollutant in the troposphere,whereas long-term measurements are scarce in rural areas in North China Plain(NCP),resulting in unclear seasonal variations and sources of PAN in rural NCP.In this study,we conducted a 1-year observation of PAN during 2021-2022 at the rural NCP site.The average concentrations of PAN were 1.10,0.75,0.65,and 0.88 ppbv in spring,summer,autumn,and winter,respectively,with a 1-year average of 0.81±0.60 ppbv.Calculations indicate that the loss of PAN through thermal decomposition in summer accounts for 43.2% of the total formed PAN,which is an important reason for the low concentration of PAN in summer.We speculate that since the correlation between PAN and O_(3) in winter is significantly lower than that in other seasons,the observed regional transport of PAN cannot be ignored in winter.Through budget analysis,regional transport accounted for 12.8% and 55.9% of the observed PAN on the spring and winter pollution days,respectively,which showed that regional transport played key roles during the photochemical pollution of the rural NCP in winter.The potential source contribution function revealed that the transported PAN mainly comes from southern Hebei in spring.In winter,the transported PAN was mainly from Langfang,Hengshui,and southern Beijing.Our findings may aid in understanding PAN variations in different seasons in rural areas and highlight the impact of regional transport on the PAN budget.

关键词： Photochemical pollution Peroxyacetyl nitrate(PAN) Seasonal variations Regional transport Rural area