Double transmission peaks electromagnetically induced transparency induced by simultaneously exciting the electric and magnetic resonance in one unit cell

In this paper, we investigate a metamaterial formed by a planar array of a metallic L-shaped structure and a cut wire(CW), which behaves as an analogue of the electromagnetically induced transparency(EIT). The double transmission peaks are formed by the destructive interference of two bright-modes and a quasi-dark mode. The two bright-modes are respectively excited by the L-shaped structure and CW. The unit structure itself performs a quasi-dark mode. The group refractive indexes are over 20 in the first transmission peak, and 117 in the second transmission peak, thus offering potential applications in slow light devices. Finally, all the above characteristics are achieved in just one simple unit cell.

Role of optimal transmission switching in accommodating renewable energy in deep peak regulation-enabled power systems

Due to the shortage of fossil energy and the pollution caused by combustion of fossil fuels,the proportion of renewable energy in power systems is gradually increasing across the world.Accordingly,the capacity of power systems to accommodate renewable energy must be improved.However,integration of a large amount of renewable energy into power grids may result in network congestion.Hence,in this study,optimal transmission switching(OTS)is considered as an important method of accommodating renewable energy.It is incorporated into the operation of a power grid along with deep peak regulation of thermal power units,forming an interactive mode of coordinated operation of source and network.A stochastic unit commitment model consider!ng deep peak regulation and OTS is established,and the role of OTS in promoting the accommodation of renewable energy is analyzed quantitatively.The results of case studies involving the IEEE 30-bus system demonstrate that OTS can enable utilization of the potential of deep peak regulation and facilitate the accommodation of renewable energy.

Combined hybrid energy storage system and transmission grid model for peak shaving based on time series operation simulation

This study proposes a combined hybrid energy storage system(HESS) and transmission grid(TG) model, and a corresponding time series operation simulation(TSOS) model is established to relieve the peak-shaving pressure of power systems under the integration of renewable energy. First, a linear model for the optimal operation of the HESS is established, which considers the different power-efficiency characteristics of the pumped storage system, electrochemical storage system, and a new type of liquid compressed air energy storage. Second, a TSOS simulation model for peak shaving is built to maximize the power entering the grid from the wind farms and HESS. Based on the proposed model, this study considers the transmission capacity of a TG. By adding the power-flow constraints of the TG, a TSOS-based HESS and TG combination model for peak shaving is established. Finally, the improved IEEE-39 and IEEE-118 bus systems were considered as examples to verify the effectiveness and feasibility of the proposed model.

Application of clutch to clutch gear shift technology for a new automatic transmission

For the purpose of engineering development for a new 8-step speed automatic transmission,a simplified dynamic model for this gearbox was established and key parameters which affected the shift quality were analyzed.Aiming at four different shift types,the ideal characteristics of shift clutch and engine control were set up.By using torque estimation method,PI slip control algorithm and engine coordinated control principle,the control model and transmission controller were well developed for three shift phases which included rapid-fill phase,torque phase and inertia phase.The testing environment on the rig and prototype vehicle level was built and the testing results obtained in ultimate condition could verify the accuracy and feasibility of this shift control strategy.The peak jerk during shift process was controlled within ±2 g/s where the smooth gearshift was obtained.The development proposal and algorithm have a high value for engineering application.

EFFICIENT IMAGE TRANSMISSION SCHEME IN FMT SYSTEM

An efficient image transmission scheme is proposed based on byte partition and adaptive sub-channel distribution technique in Filtered MultiTone (FMT) system over frequency selective slow fading channel. According to the simulation results and analysis of a typical image with matlab, improvement in Peak Signal to Noise Ratio (PSNR) of the received image and low complexity for equalization is demonstrated remarkably. Comparing with no adaptive and no actual channel equalization scheme, the proposed scheme saves over 6 dB when PSNR=40 dB.

OFDM Wireless Downhole Transmission Systems and Proposed SLM Method for PAPR Reduction

At present, mud pulse transmission systems are widely used in downhole data transmission. But the systems are very low in transmission efficiency, only 5-10 bits/s, with very large anti-inter-symbol-interference (ISI). It cannot meet high requirements for high-speed transmission of modern logging system. The development of communication technology has laid some foundation for this requirement. For this purpose, the Orthogonal Frequency Division Multiplexing (OFDM) Wireless Downhole Transmission Systems are proposed for the first time because of their high transmission rate, anti-inter-symbol-interference (ISI), and high spectral efficiency, etc. Due to non-linear power amplifier (PA) of logging systems with limited dynamic range, the drawbacks of high peak-average power ratio (PAPR) may outweigh all the potential benefits of OFDM wireless downhole transmission systems. Selective mapping (SLM) method can reduce the PAPR of OFDM logging signals without distortion. But at the receiver, the conventional SLM method needs exact bits of side information (SI) to recover the data signal. The probability of erroneous SI detection has a significant influence on the error performance of the system. And individual transmissions of SI result in the reduction of bandwidth efficiency. To restore the exact data signal, our scheme codes the SI bits by linear block codes (LBC), and is easily decoded by syndrome decoding. And then the coding SI bits are superimposed onto the logging signals to omit SI bits transmission. The theory and simulation results show that the proposed method has better performance than the conventional one. Accordingly, the OFDM wireless downhole transmission systems can tackle the high PAPR problem, and highten the transmission rate of logging signals.

中国实现碳中和:降碳风险的识别与应对

中国实现碳中和目标必将引发能源利用模式的深度变革,重塑各领域生产生活方式既是一场系统性变革,也面临微观与宏观的转型风险。从系统视角阐释中国零碳转型过程中降碳风险及其风险的系统传导机制,并基于低碳/零碳/负碳技术创新及转化的“研发—应用—推广”的阶段过程,解析了零碳转型过程中风险因素的传导路径;指出技术成熟度、产品绿色溢价、资产沉没成本、技术应用及供应链保障五类主要降碳风险,评估其对中国碳中和目标实现和社会经济发展的影响。提出中国需从系统视角慎重把握目标实现过程中的降碳风险,从政策引领、监测核算、科技人才、创新环境、国际合作等多方面共同发力和协同推进,全局把控设计应对政策措施,应深入实施低碳技术领跑者政策、加强碳排放核算与碳减排风险评估、积极培育壮大低碳技术研发力量、营造有利于低碳创新的社会环境。

齿轮传动误差峰峰值最小化的拓扑修形优化研究

为了满足齿轮传动系统低噪声、小振动和高传动精度等要求,提出了一种基于传动误差峰峰值最小化的齿轮拓扑修形优化方法。基于直线与抛物线的复合修形叠加曲线,在标准渐开线齿轮的齿廓和齿向方向对齿轮进行修形设计,提出一种拓扑修形齿面形成方法;以齿轮传动误差峰峰值最小为优化目标,基于遗传算法对提出的拓扑修形齿轮齿面进行参数优化,得出拓扑修形齿轮齿面的最佳修形参数;将拓扑修形齿轮和标准齿轮进行对比,分析修形前后齿轮的齿面受载情况和齿根应力分布情况,验证了提出的拓扑修形优化方法的有效性。

枝节直波导与开口方环耦合谐振腔的Fano谐振特性研究

本文构建了一个枝节直波导与带开口方环耦合谐振腔.基于金属-绝缘体-金属结构的Fano谐振原理,采用有限元法分析了该波导结构的透射谱线对谐振腔结构参数的依赖关系.在开口方环与直波导间距G=90 nm,枝节高度H=140 nm时,该谐振腔结构中可以产生中心波长分别为λ=746 nm和1521 nm具有反对称线型的双重Fano共振透射峰.研究表明:左侧谐振峰值先随H增高而升高,至H=140 nm达到最大值,之后随H增高峰值缓慢减弱,直至消失.右侧谐振峰值则几乎不受H变化影响.传输谷受H影响最大,随着H增大,枝节谐振腔的传输谷向长波长方向移动,而右侧两个传输谷基本保持不变.当H=210 nm时,左边Fano谐振完全消失,只剩下右边的谐振,且谐振峰基本保持不变.设置参数化扫描,观测Fano谐振的变化,在波长1500 nm~1700 nm之间,设置最佳参数,经拟合计算得到该谐振耦合腔可以作为一个灵敏度S为1496 nm/RIU,FOM=60.1的折射率传感器.该结构可以为纳米级折射率传感器设计提供有效依据.

考虑外送输电容量限制的梯级水光互补日前鲁棒调峰调度方法

水光联合外送可促进新能源消纳,但光伏出力预测的不确定性会影响水光互补优化调度的经济性和安全性。提出一种考虑外送输电容量限制的梯级水光互补联合发电系统日前鲁棒调度方法。考虑光伏出力不确定性,构建水光互补联合发电系统的日前调峰鲁棒优化调度模型,该模型以最小化受端电网剩余负荷峰谷差为目标,计及梯级水电的上、下游水力耦合约束。采用高效线性化方法对梯级水电运行的非线性模型进行处理,并利用对偶方法实现鲁棒模型的确定性转化。算例仿真结果表明,利用所提方法制定的梯级水电发电计划能充分考虑光伏出力的不确定性,兼顾联合发电系统调峰效果和光伏消纳,实现梯级水电和光伏的互补运行。

兼顾本地与直流受端电网调峰需求的水电站群短期优化调度模型

面对巨型水电站群高压直流送端电网和受端电网日益严峻的调峰压力,建立了一种兼顾本地与直流受端电网调峰需求的梯级水电站群短期优化调度模型。模型以多电网剩余负荷最大值最小为目标,考虑常规梯级水电站群水力、电力约束,以及复杂高压直流输电线路运行约束,并引入直流线路与水电站之间耦合运行约束。在模型求解阶段,引入辅助变量将目标函数、水电运行约束、直流运行约束线性化,并采用大M法对直流线路与水电站之间双向区间耦合约束进行线性化,将原模型转换为混合整数线性规划模型。以中国西南地区某巨型水电站群冬季和夏季典型日为实例研究,结果表明:送端电网负荷峰谷差降幅高达100%,受端电网负荷峰谷差降幅分别达28.1%和31.6%。所提模型能够利用高压直流输电线路共享水电灵活性,有效实现多电网调峰,并保证直流输电线路运行在安全区间,可以为巨型梯级水电站群短期多电网调峰提供参考和借鉴。

一种考虑峰荷-电量分摊机制和风电关键场景的输-配电网协同调度策略

风电功率的不确定性问题严重制约其消纳,因此,激发输-配电网积极性并提出合理的风电协同消纳方法具有重要意义。在建立改进峰荷-电量责任模型的基础上,提出一种基于场景法的输-配电网多目标协同调度模型。首先,将传统输-配电网峰荷责任模型、电量责任模型相结合,同时计入风电消纳、需求响应的影响并引入输配电成本分摊机制,建立改进输-配电网峰荷-电量责任模型。其次,针对输-配电网集中式和分布式风电出力的不确定性问题,基于风电功率日前基础预测场景和奇、偶时刻的极限爬坡场景构建关键风电场景集,并在此基础上提出输-配电网柔性资源协同调度策略。然后,将输-配电网改进峰荷-电量责任模型和柔性资源协同调度策略相结合,建立输-配多目标协同优化模型。最后,基于典型T6D2系统进行案例仿真,采用目标级联分析法对所提模型进行求解。结果表明,所提模型有利于支撑并促进输-配电网提升风电消纳水平,而峰荷-电量责任的边际效应有助于输-配电网有序制定对应责任权重,从而实现经济效益、风电消纳和社会效益的合理均衡。

气候风险情景分析与压力测试概述:基础概念与监管框架

未雨绸缪地防范气候相关金融风险的前提是能够准确识别与评估气候风险,气候风险情景分析和压力测试则恰如其分地成为有效工具之一。经过主要国际组织和部分前瞻性金融监管机构的积极实践,气候风险情景分析与压力测试正逐渐被纳入宏微观审慎监管评估工具箱之中。宏观上,监管机构定期召集金融机构开展系统性气候风险压力测试,并积极引导金融机构建立气候风险管理框架;微观上,监管机构鼓励金融机构适时地自行测试,可率先从定性的描述性情景分析开始,逐步过渡至定量的压力测试。我国将气候相关风险纳入宏观审慎监管框架的趋势日渐明朗,监管机构也积极推动气候风险情景分析和压力测试的开展,未来定期组织测试的概率很大。另外,虽然已有形式为统一化测试框架,但未来要求金融机构自行开展测试也不无可能。

基于自适应切换迭代学习的绳驱踝外骨骼力控制器设计

人-外骨骼构成强耦合系统,步态的偶然变异对控制器产生较大干扰,导致系统震荡。针对这一问题,提出了一种自适应切换的迭代学习控制策略。在峰值误差较大时,采用峰值迭代学习控制,仅对力控信号峰值点进行迭代更新;当峰值误差较小时,切换为传统的PD型迭代学习控制,对力控信号所有点进行迭代更新。为进一步改善控制效果,设计了前馈控制器来补偿鲍登绳传动的非线性摩擦。仿真和外骨骼实验结果表明,与传统PD型迭代学习算法相比,自适应切换的迭代学习控制策略保证了助力曲线的平稳升降,同时该策略具有更快的收敛速度以及受干扰后更快的恢复速度,实现了行走过程中辅助力的准确跟踪控制。

柔性直流换流站阀控系统故障分析

近年来,柔性直流输电技术已成为支撑大规模新能源消纳、能源互联网构建的主要方式之一,而阀控系统是柔性直流输电技术的关键组成部分,对电力系统安全稳定运行至关重要。以±420kV柔性直流背靠背开路试验(openlinetest,OLT)闭锁事故为研究对象,提供了一种基于顺序查找法的换流站阀控系统故障分析思路。首先介绍了柔性直流控保策略、阀控系统及其结构。随后,针对OLT过程中引起的故障闭锁事件进行介绍,并阐释了阀控系统暂时性闭锁原理。最后,根据故障录波和阀控系统架构,按顺序排查可能发生故障的位置并进行综合分析,进而确定故障原因,故障分析思路为实际工程中故障排查提供了参考。

基于偏好随机游动能量均衡算法的激光雷达数据低能耗传输

为了优化激光雷达数据的传输性能,设计一种针对激光雷达数据的低能耗传输方法。利用密度峰值快速聚类方法分割激光雷达数据噪声点,完成数据的聚类处理;采用偏好随机游动能量均衡算法规范随机游动数据;通过分解激光雷达数据传输范围设计数据传输方法,实现激光雷达数据的低能耗传输。实验结果表明,该方法在晴天、雨雪天气和雾霾天气3种不同天气下的激光雷达数据传输能耗均较低,传输激光雷达数据时可以有效减少平均节点跳数,受数据无序化影响较小,证明所提方法具有较高的实际应用价值。

“双碳”目标下西电东送输电绿色价值分配机制与策略

在全球气候变化背景下,提出“双碳”目标即碳达峰与碳中和目标旨在推动全球能源转型与绿色低碳发展。西电东送输电作为我国能源战略的重要组成部分,其绿色能源输送通道特性在实现双碳目标中发挥着关键作用。但目前输配电价体系中尚未考虑当前西电东送输电绿色价值分配机制,导致可再生能源输送越多,线路运行成本越高,通道绿色深化意愿持续走低。本文分析双碳目标与西电东送输电项目的关系,研究西电东送输电绿色价值分配机制的现状及存在的问题,并从政策、市场、技术和社会等四个方面提出了优化策略。旨在为促进西电东送输电项目的绿色价值合理分配提供理论支撑和实践指导,并提出研究的局限性和未来研究方向。

基于哈达玛矩阵的改进部分传输序列算法

部分传输序列(Partial Transmit Sequences,PTS)是一种常用的降低正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)系统峰均功率比(Peak-to-Average Power Ratio,PAPR)的方法,其能确保不给系统带来信号畸变。PTS算法的遍历特点导致计算复杂度大幅提高,文章提出的基于哈达玛矩阵的改进PTS算法将在很大程度上保障信号PAPR的性能,降低计算的复杂度。

蜂窝纸板振动传递特性测试分析

实验研究了 4种不同厚度的蜂窝纸板的振动传递特性 ,得到振动传递率曲线、峰值频率、振动传递率和阻尼比 。

考虑风电外送的省级系统调峰分析模型

风电的间歇性和反调峰性使得风电富集省面临系统调峰和能源消纳的问题,建设大功率外送通道是解决能源消纳问题有效的途径。应对外送通道建设后对系统调峰及风能消纳的影响,建立了考虑风电外送的省级系统调峰分析模型。计及风电的出力预测,将风电出力看作负的负荷,与原始负荷形成等效负荷,考虑水电机组的削峰作用和外送通道的辅助调峰作用,提出了全省常规机组的出力安排模型,并以此为基础进行调峰分析。以我国某风电大省为算例进行了模拟分析,结果表明外送通道的建设减少了系统弃风,扩大了风电的消纳范围,且促进了送端与受端的调峰互补,是风电基地持续、健康发展的根本出路。