Let M be a compact n-manifold of positive sectional curvature.We will review classical results on the fundamental group of M,a motivation on the c(n)-cyclic conjecture that the fundamental group of M contains a cyclic...Let M be a compact n-manifold of positive sectional curvature.We will review classical results on the fundamental group of M,a motivation on the c(n)-cyclic conjecture that the fundamental group of M contains a cyclic subgroup of index bounded above by c(n),a constant depending only on n,and we will survey partial results(up to date)on the c(n)-cyclic conjecture.展开更多
碳捕集与封存(Carbon capture and storage, CCS)的投资决策研究大多聚焦于单一企业的不足,从燃煤电厂角度出发,描述了两家投资主体参与市场竞争的“双寡头”情况;同时,考虑了碳价和技术创新双重不确定的影响,将碳配额和政府补贴作为鼓...碳捕集与封存(Carbon capture and storage, CCS)的投资决策研究大多聚焦于单一企业的不足,从燃煤电厂角度出发,描述了两家投资主体参与市场竞争的“双寡头”情况;同时,考虑了碳价和技术创新双重不确定的影响,将碳配额和政府补贴作为鼓励投资的激励政策,构建了CCS改造投资的实物期权评价模型。通过逆向归纳法,分别得出垄断情况和双寡头情况下的投资价值和投资临界值。研究表明:抢占投资会造成投资者的短视行为,碳价波动率、碳捕获率、技术创新幅度等参数的增大会减缓投资,政府补贴和技术创新概率的增大则会加速投资。展开更多
提高能源利用效率与增加可再生能源占比是实现“双碳”目标的重要路径。然而以热电联产机组(Combined Heat and Power,CHP)为核心单元的综合能源系统存在热电耦合约束,导致其难以集成高比例可再生能源。为解决该问题,文中提出碳捕集系统...提高能源利用效率与增加可再生能源占比是实现“双碳”目标的重要路径。然而以热电联产机组(Combined Heat and Power,CHP)为核心单元的综合能源系统存在热电耦合约束,导致其难以集成高比例可再生能源。为解决该问题,文中提出碳捕集系统(Carbon Capture System,CCS)耦合两阶段电转气(Power-to-Gas,P2G)的综合能源系统优化调度模型,同时对P2G运行所产生的氢气进行多元利用。考虑风光的不确定性,提出以成本最小与碳排放最低的多目标优化方法来平衡集成系统的经济性和碳排放量。构建算例仿真并采用gurobi求解器求解。仿真结果表明,所提方法优化了风光消纳量、碳排放量、系统成本,验证了所提模型的有效性和优越性。展开更多
以铁路控制、指挥与信号子系统互联互通技术规范(EU)2023/1695为基础,对车载命令与信号子系统(Control-Command and Signalling On-board Subsystem,CCS)在开展欧盟互联互通符合性认证过程中,如何去开展中间阶段符合性认证进行解析,分...以铁路控制、指挥与信号子系统互联互通技术规范(EU)2023/1695为基础,对车载命令与信号子系统(Control-Command and Signalling On-board Subsystem,CCS)在开展欧盟互联互通符合性认证过程中,如何去开展中间阶段符合性认证进行解析,分析中间阶段符合性认证优劣势,重点剖析和总结中间阶段符合性认证流程与各认证阶段相关工作,并给出切实可行的认证示例。希望为我国车载CCS子系统迈向国际市场提供借鉴。展开更多
To overcome the limitations of low efficiency and reliance on manual processes in the measurement of geometric parameters for bridge prefabricated components,a method based on deep learning and computer vision is deve...To overcome the limitations of low efficiency and reliance on manual processes in the measurement of geometric parameters for bridge prefabricated components,a method based on deep learning and computer vision is developed to identify the geometric parameters.The study utilizes a common precast element for highway bridges as the research subject.First,edge feature points of the bridge component section are extracted from images of the precast component cross-sections by combining the Canny operator with mathematical morphology.Subsequently,a deep learning model is developed to identify the geometric parameters of the precast components using the extracted edge coordinates from the images as input and the predefined control parameters of the bridge section as output.A dataset is generated by varying the control parameters and noise levels for model training.Finally,field measurements are conducted to validate the accuracy of the developed method.The results indicate that the developed method effectively identifies the geometric parameters of bridge precast components,with an error rate maintained within 5%.展开更多
Radar cross section(RCS)plays a critical role in modeling target scattering characteristics and enhancing the precision of target detection and localization in integrated sensing and communication(ISAC)systems.This pa...Radar cross section(RCS)plays a critical role in modeling target scattering characteristics and enhancing the precision of target detection and localization in integrated sensing and communication(ISAC)systems.This paper investigates the human body RCS at 26 GHz via multiangle channel measurements under different clothing conditions.Based on calibrated electromagnetic(EM)parameters,the RCS characteristics of the human body in far-field conditions are analyzed using ray-tracing(RT)simulations.Some suggestions for the design of ISAC systems are also discussed.The results provide a solid theoretical foundation and practical reference for the modeling of target scattering characteristics for ISAC channels.展开更多
文摘Let M be a compact n-manifold of positive sectional curvature.We will review classical results on the fundamental group of M,a motivation on the c(n)-cyclic conjecture that the fundamental group of M contains a cyclic subgroup of index bounded above by c(n),a constant depending only on n,and we will survey partial results(up to date)on the c(n)-cyclic conjecture.
文摘碳捕集与封存(Carbon capture and storage, CCS)的投资决策研究大多聚焦于单一企业的不足,从燃煤电厂角度出发,描述了两家投资主体参与市场竞争的“双寡头”情况;同时,考虑了碳价和技术创新双重不确定的影响,将碳配额和政府补贴作为鼓励投资的激励政策,构建了CCS改造投资的实物期权评价模型。通过逆向归纳法,分别得出垄断情况和双寡头情况下的投资价值和投资临界值。研究表明:抢占投资会造成投资者的短视行为,碳价波动率、碳捕获率、技术创新幅度等参数的增大会减缓投资,政府补贴和技术创新概率的增大则会加速投资。
文摘以铁路控制、指挥与信号子系统互联互通技术规范(EU)2023/1695为基础,对车载命令与信号子系统(Control-Command and Signalling On-board Subsystem,CCS)在开展欧盟互联互通符合性认证过程中,如何去开展中间阶段符合性认证进行解析,分析中间阶段符合性认证优劣势,重点剖析和总结中间阶段符合性认证流程与各认证阶段相关工作,并给出切实可行的认证示例。希望为我国车载CCS子系统迈向国际市场提供借鉴。
基金The National Natural Science Foundation of China(No.52338011,52378291)Young Elite Scientists Sponsorship Program by CAST(No.2022-2024QNRC0101).
文摘To overcome the limitations of low efficiency and reliance on manual processes in the measurement of geometric parameters for bridge prefabricated components,a method based on deep learning and computer vision is developed to identify the geometric parameters.The study utilizes a common precast element for highway bridges as the research subject.First,edge feature points of the bridge component section are extracted from images of the precast component cross-sections by combining the Canny operator with mathematical morphology.Subsequently,a deep learning model is developed to identify the geometric parameters of the precast components using the extracted edge coordinates from the images as input and the predefined control parameters of the bridge section as output.A dataset is generated by varying the control parameters and noise levels for model training.Finally,field measurements are conducted to validate the accuracy of the developed method.The results indicate that the developed method effectively identifies the geometric parameters of bridge precast components,with an error rate maintained within 5%.
基金supported by the National Natural Science Foundation of China under Grant No.62271043Ministry of Education of China under Grant No.8091B032123Beijing Natural Science Foundation under Grant No.L212029。
文摘Radar cross section(RCS)plays a critical role in modeling target scattering characteristics and enhancing the precision of target detection and localization in integrated sensing and communication(ISAC)systems.This paper investigates the human body RCS at 26 GHz via multiangle channel measurements under different clothing conditions.Based on calibrated electromagnetic(EM)parameters,the RCS characteristics of the human body in far-field conditions are analyzed using ray-tracing(RT)simulations.Some suggestions for the design of ISAC systems are also discussed.The results provide a solid theoretical foundation and practical reference for the modeling of target scattering characteristics for ISAC channels.
