This paper explores the phenomenon of fluid resonance occurring within a narrow gap between a vessel and a vertical wharf, taking ships berthing in front of a gravity wharf as the research background. Using the open-s...This paper explores the phenomenon of fluid resonance occurring within a narrow gap between a vessel and a vertical wharf, taking ships berthing in front of a gravity wharf as the research background. Using the open-source software Open FOAM~?, a two-dimensional viscous-flow numerical wave flume was developed to simulate the fluid resonant motions induced by transient focused wave groups with different spectral peak periods and wave amplitudes. The results indicate that for all the incident focused wave amplitudes considered, the amplitudes of the free surface elevation in the gap, horizontal wave force and moment all exhibit a bimodal variation trend with increasing spectral peak period. The peak values of the above amplitude-period curve appear near the resonant period of the first and second harmonic components of the free surface elevation. However, the variation in the vertical wave force versus the spectral peak period presents different patterns. In addition, the first-to fourth-order harmonic components in the wave surface and forces are further examined via the four-phase combination method. The results show that the first-to secondorder harmonic components play a dominant role in the overall amplitude.展开更多
针对火电厂分散控制系统对供电连续性要求高、不间断电源(Uninterruptible Power Supply,UPS)故障易影响系统稳定运行的问题,研究UPS可靠性提升方法。通过分析UPS设备及运行维护层面的可靠性风险,提出UPS结构与供电冗余配置优化、蓄电...针对火电厂分散控制系统对供电连续性要求高、不间断电源(Uninterruptible Power Supply,UPS)故障易影响系统稳定运行的问题,研究UPS可靠性提升方法。通过分析UPS设备及运行维护层面的可靠性风险,提出UPS结构与供电冗余配置优化、蓄电池可靠性提升及运行监测与预警机制完善等措施,并结合工程应用进行验证。结果表明,所提方法能够有效降低UPS运行故障风险,提升UPS供电可靠性,对火电厂自动化系统安全运行具有良好的工程参考价值。展开更多
为解决传统不间断电源(Uninterruptible Power Supply,UPS)远程管理系统通信存在的可靠性不足、数据传输实时性差及网络适应性弱的问题,提出融合4G、5G与Wi-Fi的多模态通信技术方案,构建具有信道质量评估能力的UPS远程管理云平台。实验...为解决传统不间断电源(Uninterruptible Power Supply,UPS)远程管理系统通信存在的可靠性不足、数据传输实时性差及网络适应性弱的问题,提出融合4G、5G与Wi-Fi的多模态通信技术方案,构建具有信道质量评估能力的UPS远程管理云平台。实验结果表明,该平台显著提升了通信连接可靠性、数据传输效率及网络环境适应性,为电力保障系统提供了可靠技术支撑。展开更多
为解决不间断电源(Uninterruptible Power Supply,UPS)切换过程中发射机监控通信短暂中断的问题,分析电压暂降、谐波干扰及电磁辐射三大成因,提出系统性的解决方案,包括针对性防护措施和数据补发机制。研究结果表明,采用超级电容缓冲、...为解决不间断电源(Uninterruptible Power Supply,UPS)切换过程中发射机监控通信短暂中断的问题,分析电压暂降、谐波干扰及电磁辐射三大成因,提出系统性的解决方案,包括针对性防护措施和数据补发机制。研究结果表明,采用超级电容缓冲、有源滤波、屏蔽敷设等措施可有效提升通信稳定性,结合滑动窗口协议可实现数据的完整恢复。展开更多
全天候广播发射站对电源系统连续性与电能质量有严苛要求,因此设计一种基于模块化架构的不间断电源(Uninterruptible Power Supply,UPS)系统。该系统对功率、电池、控制及静态开关模块进行协同设计,实现了故障冗余、毫秒级切换与谐波抑...全天候广播发射站对电源系统连续性与电能质量有严苛要求,因此设计一种基于模块化架构的不间断电源(Uninterruptible Power Supply,UPS)系统。该系统对功率、电池、控制及静态开关模块进行协同设计,实现了故障冗余、毫秒级切换与谐波抑制功能。应用案例证实,该系统能有效消除单点故障导致的停播,保障负载无缝切换,并输出满足精密设备要求的高质量电能。展开更多
算力迭代进程中,数据中心供电负荷动态波动特性持续强化。现有模块化不间断电源(Uninterruptible Power Supply,UPS)固定冗余配置模式,无法适配负荷变化节奏,引发供电资源匹配失衡、运行稳定性受限问题。研究构建冗余配置协同优化体系,...算力迭代进程中,数据中心供电负荷动态波动特性持续强化。现有模块化不间断电源(Uninterruptible Power Supply,UPS)固定冗余配置模式,无法适配负荷变化节奏,引发供电资源匹配失衡、运行稳定性受限问题。研究构建冗余配置协同优化体系,整合负载适配约束、容量编组调控、可靠度校核、无扰切换控制4项优化策略。通过多场景对比测试完成体系验证,为数据中心供电系统资源效率与运行稳定性的平衡提供可落地的技术配置路径。展开更多
为提高保护系统的适应性与可靠性,构建一种不间断电源(Uninterruptible Power Supply,UPS)并网运行模式下方向继电保护自适应整定技术模型,包括并网模式识别、故障特征提取方法以及继电保护定值自适应调整策略,基于UPS并网运行状态实时...为提高保护系统的适应性与可靠性,构建一种不间断电源(Uninterruptible Power Supply,UPS)并网运行模式下方向继电保护自适应整定技术模型,包括并网模式识别、故障特征提取方法以及继电保护定值自适应调整策略,基于UPS并网运行状态实时数据,建立自适应整定技术流程,实现保护参数动态修正。仿真验证结果表明,该技术在多种故障工况下可有效提高保护动作的正确率和响应速度。研究成果可为UPS并网场景下继电保护配置提供技术支持,具有良好工程应用前景。展开更多
为了提高通信配电系统中不间断电源(Uninterruptible Power Supply,UPS)输入级的电能质量,引入三相功率因数校正(Power Factor Correction,PFC)技术,优化UPS输入级结构,设计适用于不平衡电网条件的三相PFC拓扑与控制策略,并完成硬件选...为了提高通信配电系统中不间断电源(Uninterruptible Power Supply,UPS)输入级的电能质量,引入三相功率因数校正(Power Factor Correction,PFC)技术,优化UPS输入级结构,设计适用于不平衡电网条件的三相PFC拓扑与控制策略,并完成硬件选型与实验验证。实验结果表明,所提方案可显著提高输入端功率因数,抑制电流谐波,降低总谐波畸变率,使三相信号更加均衡。研究结果对提高UPS系统输入效率、保障电力设备稳定运行具有重要意义。展开更多
This study investigates the width of the secondary eyewall(SE)immediately following its formation in tropical cyclones with surface environmental winds aligned and counter-aligned with environmental vertical wind shea...This study investigates the width of the secondary eyewall(SE)immediately following its formation in tropical cyclones with surface environmental winds aligned and counter-aligned with environmental vertical wind shear(VWS),using idealized numerical experiments.Results reveal that the SE develops greater radial extent when surface winds align with VWS compared to counter-aligned conditions.In alignment configurations,shear-enhanced surface winds on the right flank amplify surface enthalpy fluxes,thereby elevating boundary-layer entropy within the downshear outer-core region.Subsequently,more vigorous outer rainbands develop,inducing marked acceleration of tangential winds in the outer core preceding SE formation.The resultant radial expansion of supergradient winds near the boundary-layer top triggers widespread convective activity immediately beyond the inner core.Progressive axisymmetrization of this convective forcing ultimately generates an expansive SE structure.展开更多
针对通信机房不间断电源(Uninterruptible Power Supply,UPS)系统在传统运行模式下存在的能耗高、负载率常偏离高效区间的问题,提出基于多策略改进麻雀搜索算法的动态节能优化方法。构建以系统总能耗最小化为目标的优化模型,并通过引入...针对通信机房不间断电源(Uninterruptible Power Supply,UPS)系统在传统运行模式下存在的能耗高、负载率常偏离高效区间的问题,提出基于多策略改进麻雀搜索算法的动态节能优化方法。构建以系统总能耗最小化为目标的优化模型,并通过引入混沌映射初始化、非线性递减惯性权重及动态步长调整等多种策略改进麻雀搜索算法,以高效求解最优的UPS运行参数。基于求解结果,设计动态调控策略,根据实时负载智能切换UPS工作模式并调整关键参数。测试结果表明,经所提方法优化后,机房核心设备群能耗有明显下降,且所有设备能耗均低于80 kW·h的预设阈值;在模拟多种负载工况的4个测试小组中,UPS负载率稳定在60%~80%的高效区间,保障了供电可靠性,为通信机房的绿色低碳运维提供了有效的解决方案。展开更多
This study investigates the relationship between atmospheric stratification (i.e., static stability given by N^(2)) and the vertical energy transfer of stationary planetary waves, and further illustrates the underlyin...This study investigates the relationship between atmospheric stratification (i.e., static stability given by N^(2)) and the vertical energy transfer of stationary planetary waves, and further illustrates the underlying physical mechanism. Specifically, for the simplified case of constant stratospheric N^(2), the refractive index square of planetary waves has a theoretical tendency to increase first and then decrease with an increased N^(2), whereas the group velocity weakens. Mechanistically, this behavior can be understood as an intensified suppression of vertical isentropic surface displacement caused by meridional heat transport of planetary waves under strong N^(2) conditions. Observational analysis corroborates this finding, demonstrating a reduction in the vertical-propagation velocity of waves with increased N^(2). A linear, quasi- geostrophic, mid-latitude beta-plane model with a constant background westerly wind and a prescribed N^(2) applicable to the stratosphere is used to obtain analytic solutions. In this model, the planetary waves are initiated by steady energy influx from the lower boundary. The analysis indicates that under strong N^(2) conditions, the amplitude of planetary waves can be sufficiently increased by the effective energy convergence due to the slowing vertical energy transfer, resulting in a streamfunction response in this model that contains more energy. For N^(2) with a quasi-linear vertical variation, the results bear a resemblance to the constant case, except that the wave amplitude and oscillating frequency show some vertical variations.展开更多
The dense heterogeneous network provides standardized connectivity and access guarantees for 5G communication services.However,the complex network environment and high level of dynamism pose challenges to network sele...The dense heterogeneous network provides standardized connectivity and access guarantees for 5G communication services.However,the complex network environment and high level of dynamism pose challenges to network selection decisions.Existing vertical handover algorithms often overlook the dynamic nature of user mobility and network condition,resulting in problems such as handover failure and frequent handover,ultimately impacting the quality of the user communication service.To address these problems,we propose an intelligent switching method,iMALSTM-DQN,which integrates an improved Multi-level Associative Long Short-Term Memory model(iMALSTM)with Deep Reinforcement Learning(DRL).The algorithm leverages iMALSTM to predict the global network state in the next moment based on the global user movement trajectory and historical network status information within a region,thereby enhancing the prediction accuracy of network states.Subsequently,based on the predicted network state,we employ the Deep Q Network(DON)model to make handover decisions,adaptively determining the optimal switching and network selection strategy through interaction with the environment.Experimental results demonstrate that the proposed algorithm enhances decision timeliness,significantly reduces the number of switch failures,and alleviates the problem of frequent handovers resulting from network dynamics.展开更多
Two-step-processed(TSP)inverted p-i-n perovskite solar cells(PSCs)have demonstrated significant promise in tandem applications.However,the power conversion efficiency(PCE)of TSP p-i-n PSCs rarely exceeds 24%.Here,we d...Two-step-processed(TSP)inverted p-i-n perovskite solar cells(PSCs)have demonstrated significant promise in tandem applications.However,the power conversion efficiency(PCE)of TSP p-i-n PSCs rarely exceeds 24%.Here,we demonstrate that TSP perovskite films exhibit a vertically gradient distribution of residual PbI_(2)clusters,which form Schottky heterojunctions with the perovskite,leading to substantial interfacial energy-level mismatches within NiO_(x)-based TSP p-i-n PSCs.These limitations were effectively addressed via a vertical interfacial engineering enabled by dual-interface modification incorporating tin trifluoromethanesulfonate(Sn(OTF)_(2))and 4-Fluorophenylethylamine chloride(F-PEA)at the NiO_(x)/perovskite and perovskite/C60 interfaces,respectively.The functional Sn(OTF)_(2)not only enhances the conductivity of NiO_(x)films but also suppresses ion migration,while inducing the formation of a Pb-Sn mixed perovskite interlayer that precisely regulates the energy level at the NiO_(x)/perovskite interface.Complementally,F-PEA post-treatment effectively converts surface residual PbI_(2)clusters into a 2D perovskite capping layer,which simultaneously passivates surface defects and enhances energy-level alignment at the perovskite/C60 interface.Consequently,the optimized NiO_(x)-based TSP p-i-n PSCs achieve a notable PCE of 25.6%with superior operational stability.This study elucidates the underlying mechanisms limiting the efficiency of TSP p-i-n PSCs,while establishing design principles for these devices targeting 26%efficiency.展开更多
The vertical heterogeneity of the pore structure in deep coal seams with varying ash yields is a key control for coalbed methane storage and producibility;however,its specific impact on gas adsorption is not clearly d...The vertical heterogeneity of the pore structure in deep coal seams with varying ash yields is a key control for coalbed methane storage and producibility;however,its specific impact on gas adsorption is not clearly defined.The focus of this study is the No.8 coal seam of the Carboniferous Benxi Formation in the Central-Eastern Ordos Basin.By integrating microscopic identification,proximate analysis,gas adsorption(CO_(2),N_(2),and CH_(4)),and the multifractal theory,we quantitatively characterized the nanopore structure(micropores<2 nm and mesopores 2 nm-100 nm)of coal reservoirs with varying ash yields.The results indicate that(1)ash yield is the primary factor that controls the vertical evolution of pore structures in coal seams.In low-ash yield coal seams,the extent of thermal evolution and ash yield jointly constrain the heterogeneity of pore size distribution.In mediumto high-ash yield coal seams,the heterogeneity of pore structure and pore size distribution are predominantly constrained by ash yield.(2)As the ash yield vertically increases,the mesoporous pore volume and specific surface area initially decrease and subsequently increase,while the contribution of micropores to both pore volume and specific surface area continuously diminishes.Consequently,the total pore volume and specific surface area of the coal samples exhibit a two-stage reduction close to an ash yield threshold of approximately 20%.(3)Further,the Langmuir volume for CH_(4)adsorption sharply declines below the 20%threshold,followed by a gradual decrease;in contrast,the Langmuir pressure initially decreases and subsequently increases.Hence,the vertical increase in ash yield constrains the development of pore systems and diminishes pore connectivity,thereby reducing methane adsorption capacity and adversely affecting coalbed methane productivity.(4)Low-ash yield coal reservoirs are characterized by a rapid gas breakthrough and high productivity,whereas medium-ash yield coal reservoirs generally require prolonged depressurization to achieve peak gas production.These findings reveal that in medium-high rank coal,ash yield―and not thermal evolution―is the main factor that controls vertical pore evolution and methane adsorption efficiency.The quantitative ash yield threshold(20%)established in this study provides a practical criterion for evaluating reservoir quality and predicting vertical variations in gas storage potential in the Ordos Basin.展开更多
As a key precursor of hydroxyl(OH) radicals, the budget of nitrous acid(HONO) at different altitudes has received extensive attention. In this study, vertically resolved observations of HONO, NO_(2), O_(3), and HCHO w...As a key precursor of hydroxyl(OH) radicals, the budget of nitrous acid(HONO) at different altitudes has received extensive attention. In this study, vertically resolved observations of HONO, NO_(2), O_(3), and HCHO were conducted during an autumn field campaign in Beijing in 2019. The significant correlation between HONO and NO2, along with variations in their ratios across different altitudes, underscores the importance of aerosol surface chemistry in HONO formation and its altitude-dependent behavior. To enhance the model performance, the heterogeneous conversion of NO_(2) and its photochemical enhancement are incorporated into the 1D model. The simulations reveal that the nocturnal HONO production is dominated by the heterogeneous conversion of NO_(2) both at the surface and aloft. During the daytime, groundsurface sources of HONO are mainly driven by nitrate photolysis and light-enhanced heterogeneous conversion of NO_(2).Meanwhile, a large portion of the HONO generated at the surface is transported upwards through vertical mixing. In the higher atmosphere, HONO originates from vertical transport and in situ processes. As precursors of OH radicals, the observed concentrations of HONO, O_(3), and HCHO exhibit distinct diurnal variations and vertical distribution patterns.HONO contributes to OH radical production predominantly during the early morning across all layers and it even becomes the main contributor throughout the daytime in the lowest layer near the ground, while O_(3) and HCHO become more prominent towards midday, especially in the higher layers. These results will be beneficial for a deeper understanding of the atmospheric oxidation process within the urban boundary layer.展开更多
Understanding the fracture behavior of vertical cracks in piezoelectric semiconductor(PS)structures is vital due to their impacts on device reliability.This study establishes a model for a PS strip with a vertical cra...Understanding the fracture behavior of vertical cracks in piezoelectric semiconductor(PS)structures is vital due to their impacts on device reliability.This study establishes a model for a PS strip with a vertical crack under combined mechanical and electric loading,considering both central and edge cracks.Using Fourier transforms and dislocation density functions,the Mode-Ⅲproblem is converted to Cauchy-type singular integral equations.The crack surface fields,intensity factors,and energy release rate are derived.The accuracy of the proposed model is verified through the finite element(FE)simulation via COMSOL Multiphysics.The results for low electron concentrations align with those of the intrinsic piezoelectric materials,validating the correctness of the present model as well.The combined effects of crack position,applied electric loading,and initial carrier concentration on the crack propagation are analyzed.The normalized electric displacement factor shows heightened sensitivity to crack size,electromechanical loading,and carrier concentration.The crack position significantly influences the crack surface fields and normalized intensity factors due to the boundary proximity effect.展开更多
To characterize the spatial patterns of vertical crustal movement of Chinese mainland,GNSS imaging technology was applied to map the tectonic deformation of the region.In this study,the vertical crustal velocities inf...To characterize the spatial patterns of vertical crustal movement of Chinese mainland,GNSS imaging technology was applied to map the tectonic deformation of the region.In this study,the vertical crustal velocities inferred from GNSS data for Chinese mainland over two decades were rigorously estimated.First,by analyzing the vertical displacement time series from continuous GNSS stations and environmental load data,we found that the annual and semi-annual vertical displacements are highly correlated.This indicates that the vertical seasonal variations on the ground surface are mainly caused by environmental loading.After removing the seasonal variations caused by environmental loads from the GNSS time series,we applied an improved PCA technique to filter out common mode errors.Next,we estimated the optimal noise models for the filtered time series and derived the vertical velocity field of Chinese mainland.Finally,we employed an empirical Spatial Structure Function(SSF)to image the tectonic deformation of Chinese mainland.This method effectively mitigates issues with abrupt circular arc-shaped boundaries in GNSS imaging caused by sparse station networks.The imaging results show that vertical crustal deformation in Chinese mainland generally ranges from-3 to 3 mm/yr,with significant spatial variability.The central and northern parts of Qinghai-Xizang Plateau are identified as primary subsidence zones,indicating that plate boundaries and tectonic compression continue to shape the crustal movement in these regions.The major uplift zones are located in northern and central China,likely linked to regional tectonic activity and plate compression.Subsidence deformation in parts of eastern China appears to be influenced by human activities.展开更多
基金financially supported by the National Natural Science Foundation of China (Grant No. 52371277)the State Key Laboratory of Hydraulic Engineering Intelligent Construction and Operation (Tianjin University)(Grant No. HESS-2323)+2 种基金the Postgraduate Research&Practice Innovation Program of Jiangsu Province (Grant No. KYCX24_4071)the Guangdong Basic and Applied Basic Research Foundation (Grant No. 2023A1515010890)the Open foundation of Key Laboratory of Port.Waterway&Sedimentation Engineering (Grant No. Yk224001-1)。
文摘This paper explores the phenomenon of fluid resonance occurring within a narrow gap between a vessel and a vertical wharf, taking ships berthing in front of a gravity wharf as the research background. Using the open-source software Open FOAM~?, a two-dimensional viscous-flow numerical wave flume was developed to simulate the fluid resonant motions induced by transient focused wave groups with different spectral peak periods and wave amplitudes. The results indicate that for all the incident focused wave amplitudes considered, the amplitudes of the free surface elevation in the gap, horizontal wave force and moment all exhibit a bimodal variation trend with increasing spectral peak period. The peak values of the above amplitude-period curve appear near the resonant period of the first and second harmonic components of the free surface elevation. However, the variation in the vertical wave force versus the spectral peak period presents different patterns. In addition, the first-to fourth-order harmonic components in the wave surface and forces are further examined via the four-phase combination method. The results show that the first-to secondorder harmonic components play a dominant role in the overall amplitude.
文摘针对火电厂分散控制系统对供电连续性要求高、不间断电源(Uninterruptible Power Supply,UPS)故障易影响系统稳定运行的问题,研究UPS可靠性提升方法。通过分析UPS设备及运行维护层面的可靠性风险,提出UPS结构与供电冗余配置优化、蓄电池可靠性提升及运行监测与预警机制完善等措施,并结合工程应用进行验证。结果表明,所提方法能够有效降低UPS运行故障风险,提升UPS供电可靠性,对火电厂自动化系统安全运行具有良好的工程参考价值。
文摘为解决传统不间断电源(Uninterruptible Power Supply,UPS)远程管理系统通信存在的可靠性不足、数据传输实时性差及网络适应性弱的问题,提出融合4G、5G与Wi-Fi的多模态通信技术方案,构建具有信道质量评估能力的UPS远程管理云平台。实验结果表明,该平台显著提升了通信连接可靠性、数据传输效率及网络环境适应性,为电力保障系统提供了可靠技术支撑。
文摘为解决不间断电源(Uninterruptible Power Supply,UPS)切换过程中发射机监控通信短暂中断的问题,分析电压暂降、谐波干扰及电磁辐射三大成因,提出系统性的解决方案,包括针对性防护措施和数据补发机制。研究结果表明,采用超级电容缓冲、有源滤波、屏蔽敷设等措施可有效提升通信稳定性,结合滑动窗口协议可实现数据的完整恢复。
文摘全天候广播发射站对电源系统连续性与电能质量有严苛要求,因此设计一种基于模块化架构的不间断电源(Uninterruptible Power Supply,UPS)系统。该系统对功率、电池、控制及静态开关模块进行协同设计,实现了故障冗余、毫秒级切换与谐波抑制功能。应用案例证实,该系统能有效消除单点故障导致的停播,保障负载无缝切换,并输出满足精密设备要求的高质量电能。
文摘算力迭代进程中,数据中心供电负荷动态波动特性持续强化。现有模块化不间断电源(Uninterruptible Power Supply,UPS)固定冗余配置模式,无法适配负荷变化节奏,引发供电资源匹配失衡、运行稳定性受限问题。研究构建冗余配置协同优化体系,整合负载适配约束、容量编组调控、可靠度校核、无扰切换控制4项优化策略。通过多场景对比测试完成体系验证,为数据中心供电系统资源效率与运行稳定性的平衡提供可落地的技术配置路径。
文摘为提高保护系统的适应性与可靠性,构建一种不间断电源(Uninterruptible Power Supply,UPS)并网运行模式下方向继电保护自适应整定技术模型,包括并网模式识别、故障特征提取方法以及继电保护定值自适应调整策略,基于UPS并网运行状态实时数据,建立自适应整定技术流程,实现保护参数动态修正。仿真验证结果表明,该技术在多种故障工况下可有效提高保护动作的正确率和响应速度。研究成果可为UPS并网场景下继电保护配置提供技术支持,具有良好工程应用前景。
文摘为了提高通信配电系统中不间断电源(Uninterruptible Power Supply,UPS)输入级的电能质量,引入三相功率因数校正(Power Factor Correction,PFC)技术,优化UPS输入级结构,设计适用于不平衡电网条件的三相PFC拓扑与控制策略,并完成硬件选型与实验验证。实验结果表明,所提方案可显著提高输入端功率因数,抑制电流谐波,降低总谐波畸变率,使三相信号更加均衡。研究结果对提高UPS系统输入效率、保障电力设备稳定运行具有重要意义。
基金jointly supported by the National Natural Science Foundation of China[grant numbers U2342202,42175005,and 42175016]the Qing Lan Project[grant number R2023Q06]。
文摘This study investigates the width of the secondary eyewall(SE)immediately following its formation in tropical cyclones with surface environmental winds aligned and counter-aligned with environmental vertical wind shear(VWS),using idealized numerical experiments.Results reveal that the SE develops greater radial extent when surface winds align with VWS compared to counter-aligned conditions.In alignment configurations,shear-enhanced surface winds on the right flank amplify surface enthalpy fluxes,thereby elevating boundary-layer entropy within the downshear outer-core region.Subsequently,more vigorous outer rainbands develop,inducing marked acceleration of tangential winds in the outer core preceding SE formation.The resultant radial expansion of supergradient winds near the boundary-layer top triggers widespread convective activity immediately beyond the inner core.Progressive axisymmetrization of this convective forcing ultimately generates an expansive SE structure.
文摘针对通信机房不间断电源(Uninterruptible Power Supply,UPS)系统在传统运行模式下存在的能耗高、负载率常偏离高效区间的问题,提出基于多策略改进麻雀搜索算法的动态节能优化方法。构建以系统总能耗最小化为目标的优化模型,并通过引入混沌映射初始化、非线性递减惯性权重及动态步长调整等多种策略改进麻雀搜索算法,以高效求解最优的UPS运行参数。基于求解结果,设计动态调控策略,根据实时负载智能切换UPS工作模式并调整关键参数。测试结果表明,经所提方法优化后,机房核心设备群能耗有明显下降,且所有设备能耗均低于80 kW·h的预设阈值;在模拟多种负载工况的4个测试小组中,UPS负载率稳定在60%~80%的高效区间,保障了供电可靠性,为通信机房的绿色低碳运维提供了有效的解决方案。
基金supported by the National Natural Science Foundation of China(Grant No.42261134532,42405059,and U2342212)。
文摘This study investigates the relationship between atmospheric stratification (i.e., static stability given by N^(2)) and the vertical energy transfer of stationary planetary waves, and further illustrates the underlying physical mechanism. Specifically, for the simplified case of constant stratospheric N^(2), the refractive index square of planetary waves has a theoretical tendency to increase first and then decrease with an increased N^(2), whereas the group velocity weakens. Mechanistically, this behavior can be understood as an intensified suppression of vertical isentropic surface displacement caused by meridional heat transport of planetary waves under strong N^(2) conditions. Observational analysis corroborates this finding, demonstrating a reduction in the vertical-propagation velocity of waves with increased N^(2). A linear, quasi- geostrophic, mid-latitude beta-plane model with a constant background westerly wind and a prescribed N^(2) applicable to the stratosphere is used to obtain analytic solutions. In this model, the planetary waves are initiated by steady energy influx from the lower boundary. The analysis indicates that under strong N^(2) conditions, the amplitude of planetary waves can be sufficiently increased by the effective energy convergence due to the slowing vertical energy transfer, resulting in a streamfunction response in this model that contains more energy. For N^(2) with a quasi-linear vertical variation, the results bear a resemblance to the constant case, except that the wave amplitude and oscillating frequency show some vertical variations.
基金National Key Research and Development Program of China(No.2022YFB3903404,2024YFC3015403)National Natural Science Foundation of China(NSFC No.42271431,42271425)Hubei Province Major Science and Technology Innovation Program(2024BAA011)。
文摘The dense heterogeneous network provides standardized connectivity and access guarantees for 5G communication services.However,the complex network environment and high level of dynamism pose challenges to network selection decisions.Existing vertical handover algorithms often overlook the dynamic nature of user mobility and network condition,resulting in problems such as handover failure and frequent handover,ultimately impacting the quality of the user communication service.To address these problems,we propose an intelligent switching method,iMALSTM-DQN,which integrates an improved Multi-level Associative Long Short-Term Memory model(iMALSTM)with Deep Reinforcement Learning(DRL).The algorithm leverages iMALSTM to predict the global network state in the next moment based on the global user movement trajectory and historical network status information within a region,thereby enhancing the prediction accuracy of network states.Subsequently,based on the predicted network state,we employ the Deep Q Network(DON)model to make handover decisions,adaptively determining the optimal switching and network selection strategy through interaction with the environment.Experimental results demonstrate that the proposed algorithm enhances decision timeliness,significantly reduces the number of switch failures,and alleviates the problem of frequent handovers resulting from network dynamics.
基金financially supported by the National Nature Science Foundation of China (62504130)National Key Research and Development Program of China (2018YFB0704100)+3 种基金the Key university laboratory of highly efficient utilization of solar energy and sustainable development of Guangdong (Y01256331)the Technology Development Project of Henan Province (252102240047)the Pico Center at SUSTech CRF which receives support from the Presidential FundDevelopment and Reform Commission of Shenzhen Municipality
文摘Two-step-processed(TSP)inverted p-i-n perovskite solar cells(PSCs)have demonstrated significant promise in tandem applications.However,the power conversion efficiency(PCE)of TSP p-i-n PSCs rarely exceeds 24%.Here,we demonstrate that TSP perovskite films exhibit a vertically gradient distribution of residual PbI_(2)clusters,which form Schottky heterojunctions with the perovskite,leading to substantial interfacial energy-level mismatches within NiO_(x)-based TSP p-i-n PSCs.These limitations were effectively addressed via a vertical interfacial engineering enabled by dual-interface modification incorporating tin trifluoromethanesulfonate(Sn(OTF)_(2))and 4-Fluorophenylethylamine chloride(F-PEA)at the NiO_(x)/perovskite and perovskite/C60 interfaces,respectively.The functional Sn(OTF)_(2)not only enhances the conductivity of NiO_(x)films but also suppresses ion migration,while inducing the formation of a Pb-Sn mixed perovskite interlayer that precisely regulates the energy level at the NiO_(x)/perovskite interface.Complementally,F-PEA post-treatment effectively converts surface residual PbI_(2)clusters into a 2D perovskite capping layer,which simultaneously passivates surface defects and enhances energy-level alignment at the perovskite/C60 interface.Consequently,the optimized NiO_(x)-based TSP p-i-n PSCs achieve a notable PCE of 25.6%with superior operational stability.This study elucidates the underlying mechanisms limiting the efficiency of TSP p-i-n PSCs,while establishing design principles for these devices targeting 26%efficiency.
基金sponsored by the National Natural Science Foundation of China(Grant No.42202205)Natural Science Foundation of Shandong Province,China(Grant No.ZR2021QD072).-。
文摘The vertical heterogeneity of the pore structure in deep coal seams with varying ash yields is a key control for coalbed methane storage and producibility;however,its specific impact on gas adsorption is not clearly defined.The focus of this study is the No.8 coal seam of the Carboniferous Benxi Formation in the Central-Eastern Ordos Basin.By integrating microscopic identification,proximate analysis,gas adsorption(CO_(2),N_(2),and CH_(4)),and the multifractal theory,we quantitatively characterized the nanopore structure(micropores<2 nm and mesopores 2 nm-100 nm)of coal reservoirs with varying ash yields.The results indicate that(1)ash yield is the primary factor that controls the vertical evolution of pore structures in coal seams.In low-ash yield coal seams,the extent of thermal evolution and ash yield jointly constrain the heterogeneity of pore size distribution.In mediumto high-ash yield coal seams,the heterogeneity of pore structure and pore size distribution are predominantly constrained by ash yield.(2)As the ash yield vertically increases,the mesoporous pore volume and specific surface area initially decrease and subsequently increase,while the contribution of micropores to both pore volume and specific surface area continuously diminishes.Consequently,the total pore volume and specific surface area of the coal samples exhibit a two-stage reduction close to an ash yield threshold of approximately 20%.(3)Further,the Langmuir volume for CH_(4)adsorption sharply declines below the 20%threshold,followed by a gradual decrease;in contrast,the Langmuir pressure initially decreases and subsequently increases.Hence,the vertical increase in ash yield constrains the development of pore systems and diminishes pore connectivity,thereby reducing methane adsorption capacity and adversely affecting coalbed methane productivity.(4)Low-ash yield coal reservoirs are characterized by a rapid gas breakthrough and high productivity,whereas medium-ash yield coal reservoirs generally require prolonged depressurization to achieve peak gas production.These findings reveal that in medium-high rank coal,ash yield―and not thermal evolution―is the main factor that controls vertical pore evolution and methane adsorption efficiency.The quantitative ash yield threshold(20%)established in this study provides a practical criterion for evaluating reservoir quality and predicting vertical variations in gas storage potential in the Ordos Basin.
基金supported by the National Natural Science Foundation of China (Grant Nos.42075097,42177081 and 22176037)。
文摘As a key precursor of hydroxyl(OH) radicals, the budget of nitrous acid(HONO) at different altitudes has received extensive attention. In this study, vertically resolved observations of HONO, NO_(2), O_(3), and HCHO were conducted during an autumn field campaign in Beijing in 2019. The significant correlation between HONO and NO2, along with variations in their ratios across different altitudes, underscores the importance of aerosol surface chemistry in HONO formation and its altitude-dependent behavior. To enhance the model performance, the heterogeneous conversion of NO_(2) and its photochemical enhancement are incorporated into the 1D model. The simulations reveal that the nocturnal HONO production is dominated by the heterogeneous conversion of NO_(2) both at the surface and aloft. During the daytime, groundsurface sources of HONO are mainly driven by nitrate photolysis and light-enhanced heterogeneous conversion of NO_(2).Meanwhile, a large portion of the HONO generated at the surface is transported upwards through vertical mixing. In the higher atmosphere, HONO originates from vertical transport and in situ processes. As precursors of OH radicals, the observed concentrations of HONO, O_(3), and HCHO exhibit distinct diurnal variations and vertical distribution patterns.HONO contributes to OH radical production predominantly during the early morning across all layers and it even becomes the main contributor throughout the daytime in the lowest layer near the ground, while O_(3) and HCHO become more prominent towards midday, especially in the higher layers. These results will be beneficial for a deeper understanding of the atmospheric oxidation process within the urban boundary layer.
基金Project supported by the Guangdong Basic and Applied Basic Research Foundation of China(Nos.2022B1515020099 and 2024A1515240026)the National Natural Science Foundation of China(No.12372147)the Fundamental Research Funds for the Central Universities of China(No.HIT.OCEF.2024019)。
文摘Understanding the fracture behavior of vertical cracks in piezoelectric semiconductor(PS)structures is vital due to their impacts on device reliability.This study establishes a model for a PS strip with a vertical crack under combined mechanical and electric loading,considering both central and edge cracks.Using Fourier transforms and dislocation density functions,the Mode-Ⅲproblem is converted to Cauchy-type singular integral equations.The crack surface fields,intensity factors,and energy release rate are derived.The accuracy of the proposed model is verified through the finite element(FE)simulation via COMSOL Multiphysics.The results for low electron concentrations align with those of the intrinsic piezoelectric materials,validating the correctness of the present model as well.The combined effects of crack position,applied electric loading,and initial carrier concentration on the crack propagation are analyzed.The normalized electric displacement factor shows heightened sensitivity to crack size,electromechanical loading,and carrier concentration.The crack position significantly influences the crack surface fields and normalized intensity factors due to the boundary proximity effect.
基金National Natural Science Foundation of China(42274012,42004001)the Science and Technology Innovation Project of Anhui Surveying and Mapping Bureau(2025-KJ-08)+1 种基金the Open Fund of Wuhan Gravitation and Solid Earth Tides,National Observation and Research Station(WHYWZ202107)the Fundamental Research Funds for the Central Universities(JZ2022HGTB0268)。
文摘To characterize the spatial patterns of vertical crustal movement of Chinese mainland,GNSS imaging technology was applied to map the tectonic deformation of the region.In this study,the vertical crustal velocities inferred from GNSS data for Chinese mainland over two decades were rigorously estimated.First,by analyzing the vertical displacement time series from continuous GNSS stations and environmental load data,we found that the annual and semi-annual vertical displacements are highly correlated.This indicates that the vertical seasonal variations on the ground surface are mainly caused by environmental loading.After removing the seasonal variations caused by environmental loads from the GNSS time series,we applied an improved PCA technique to filter out common mode errors.Next,we estimated the optimal noise models for the filtered time series and derived the vertical velocity field of Chinese mainland.Finally,we employed an empirical Spatial Structure Function(SSF)to image the tectonic deformation of Chinese mainland.This method effectively mitigates issues with abrupt circular arc-shaped boundaries in GNSS imaging caused by sparse station networks.The imaging results show that vertical crustal deformation in Chinese mainland generally ranges from-3 to 3 mm/yr,with significant spatial variability.The central and northern parts of Qinghai-Xizang Plateau are identified as primary subsidence zones,indicating that plate boundaries and tectonic compression continue to shape the crustal movement in these regions.The major uplift zones are located in northern and central China,likely linked to regional tectonic activity and plate compression.Subsidence deformation in parts of eastern China appears to be influenced by human activities.
