Depth Profiles of Absorbed Hydrogen in Ni-Nb-Zr Amorphous Alloy Ribbons by Glow Discharge Optical Emission Spectroscopy

Depth profiles of absorbed hydrogen introduced by electrochemical charging and light elements were analyzed in Ni-Nb-Zr-H amorphous alloy ribbons using a glow discharge optical emission spectrometer. It was clarified that the absorbed hydrogen was comparatively well-distributed on the sample surface and that the content of the hydrogen decreased with increasing depth from the surface. That is, the amount of absorbed hydrogen on the surface was about 17 at %, while that inside the specimens decreased to several atomic percent. The depth profiles of the hydrogen which were close to the surface were slightly different between those on the roller side and those on the free side in the melt-spun ribbon. The difference is thought to originate from the existence of oxygen impurity on the surface and from the difference of the Zr content.

基于跌坎压力自相似分布的明渠水深−流量关系推求

明渠流量计量是高效灌溉、合理分配水资源和进行用水有效管理的重要手段。跌水是常见的明渠水流上下游衔接的水利设施。当跌落水流不受跌坎下游水流影响时形成自由跌流,可用于明渠流量的精确计量。受自由跌流影响,跌坎断面水流由缓流向急流转变,压力分布显著偏离静水压力分布规律。而获得跌坎压力分布及其准确描述方程则正是明渠自由跌流流量公式推求的关键,其准确与否决定了利用跌流进行流量计量的精度。本文首先通过模型试验和数值计算对矩形明渠自由跌流的断面压力分布特征进行研究,而后利用理论推导建立了明渠跌流的水深−流量关系公式。研究发现,明渠跌水跌坎断面压力呈典型自相似分布规律,其无量纲压力值分布倾向于一条曲线,压力最大值为0.238he(he为跌坎水深),出现在竖向距跌坎0.209he水深处,并且压力自相似分布规律与明渠流量、渠道底坡和边壁糙率无关。在此基础上,结合幂函数和尾迹函数提出了描述跌坎断面压力分布的函数方程,并给出了最大压力和最大压力位置的计算公式,然后根据动量方程和流量连续方程推求了明渠自由跌流的流量计算公式。最后,对本文和其他研究者提出的流量计算公式采用试验数据进行了对比分析,结果表明:本文提出的流量公式在明渠流量为5~100 L/s,底坡为–0.0112~0.0534、糙率为0.0930~0.0193的研究范围内,具有更高的精度和适用性,计算误差在±5%之内,可适用于该流量、底坡和边壁糙率范围内矩形明渠自由跌流的流量精确计算。本文研究结果对于利用自由跌流进行明渠流量计量提供了理论与技术支撑,具有重要的工程应用价值。

考虑充放电策略对储能寿命影响的新型分布式储能优化配置研究

针对储能使用寿命在投资决策中的关键作用及其与充放电策略和放电深度的非线性复杂关系,提出一种考虑充放电策略对储能寿命影响的新型储能规划配置方法。首先,根据放电深度与储能寿命及循环次数的关系建立了储能年等效额定放电量计算方法。其次,建立考虑充放电策略对储能寿命影响的电池储能优化配置模型,在确保储能设计使用寿命的同时使储能全寿命周期内的收益最大。而且进一步提出了改进的多种群遗传算法进行优化求解,提高了求解速度与收敛性。最后,利用改进的IEEE-39节点风光水系统进行测试,证实了方法的有效性。

A review of microwave-metal discharge interaction:Mechanism,regulation,and application for synthesis of nanomaterials

Placing metals within microwave ovens has been generally viewed as a dangerous practice because of occurrence of violent discharge,but in recent years such discharge phenomenon has attracted increasing attention and has enabled a variety of exciting applications.In this work,we provide a comprehensive review of fundamental understanding of microwave-metal discharge interaction and its state-of-the-art application for nanomaterials synthesis.We introduce the microscopic interaction between different categories of materials and the electric and magnetic field of microwaves.For microwave-metal interaction,we highlight its size-dependence and point out the influence of the oxide layer on the surface of metals.We discuss the required conditions for occurrence of discharge,microscopic formation mechanism,and characteristic features of microwave-metal discharge processes.Through analyzing the influence from the microwave input,discharging metals,and surrounding discharging media,we discuss the strategy for systematical regulation of the discharge process.We describe the applications of the microwave-metal discharge for facile synthesis of various functional nanomaterials including core-shell carbon/metal,metal oxides,metal chalcogenides,intermetallic compounds,metallic nanoparticles and metallic compounds,and organic compounds.Finally,the challenges in precise characterization and dynamic regulation of the discharge process as well as exciting application opportunities are discussed.

Low-temperature replacement construction of three-dimensional corrosion-resistant interface for deeply rechargeable Zn metal batteries

Aqueous Zn batteries are promising candidates for grid-scale renewable energy storage.Foil electrodes have been widely investigated and applied as anode materials for aqueous Zn batteries,however,they suffer from limited surface area and severe interfacial issues including metallic dendrites and corrosion side reactions,limiting the depth of discharge(DOD)of the foil electrode materials.Herein,a low-temperature replacement reaction is utilized to in-situ construct a three-dimensional(3D)corrosion-resistant interface for deeply rechargeable Zn foil electrodes.Specifically,the deliberate low-temperature environment controlled the replacement rate between polycrystalline Zn metal and oxalic acid,producing a Zn foil electrode with distinct 3D corrosion-resistant interface(3DCI-Zn),which differed from conventional two-dimensional(2D)protective structure and showed an order of magnitude higher surface area.Consequently,the 3DCI-Zn electrode exhibited dendrite-free and anticorrosion properties,and achieved stable plating/stripping performance for 1000 h at 10 mA cm^(-2)and 10 mAh cm^(-2)with a remarkable DOD of 79%.After pairing with a MnO2cathode with a high areal capacity of 4.2 mAh cm^(-2),the pouch cells delivered 168 Wh L^(-1)and a capacity retention of 89.7%after 100 cycles with a low negative/positive(N/P)ratio of 3:1.

Design Strategies for Aqueous Zinc Metal Batteries with High Zinc Utilization: From Metal Anodes to Anode-Free Structures

Aqueous zinc metal batteries(AZMBs)are promising candidates for next-generation energy storage due to the excellent safety, environmental friendliness, natural abundance, high theoretical specific capacity, and low redox potential of zinc(Zn) metal. However,several issues such as dendrite formation, hydrogen evolution, corrosion, and passivation of Zn metal anodes cause irreversible loss of the active materials. To solve these issues, researchers often use large amounts of excess Zn to ensure a continuous supply of active materials for Zn anodes. This leads to the ultralow utilization of Zn anodes and squanders the high energy density of AZMBs. Herein, the design strategies for AZMBs with high Zn utilization are discussed in depth, from utilizing thinner Zn foils to constructing anode-free structures with theoretical Zn utilization of 100%, which provides comprehensive guidelines for further research. Representative methods for calculating the depth of discharge of Zn anodes with different structures are first summarized. The reasonable modification strategies of Zn foil anodes, current collectors with pre-deposited Zn, and anode-free aqueous Zn metal batteries(AF-AZMBs) to improve Zn utilization are then detailed. In particular, the working mechanism of AF-AZMBs is systematically introduced. Finally, the challenges and perspectives for constructing high-utilization Zn anodes are presented.

Empowering the Future: Exploring the Construction and Characteristics of Lithium-Ion Batteries

Lithium element has attracted remarkable attraction for energy storage devices, over the past 30 years. Lithium is a light element and exhibits the low atomic number 3, just after hydrogen and helium in the periodic table. The lithium atom has a strong tendency to release one electron and constitute a positive charge, as Li . Initially, lithium metal was employed as a negative electrode, which released electrons. However, it was observed that its structure changed after the repetition of charge-discharge cycles. To remedy this, the cathode mainly consisted of layer metal oxide and olive, e.g., cobalt oxide, LiFePO4, etc., along with some contents of lithium, while the anode was assembled by graphite and silicon, etc. Moreover, the electrolyte was prepared using the lithium salt in a suitable solvent to attain a greater concentration of lithium ions. Owing to the lithium ions’ role, the battery’s name was mentioned as a lithium-ion battery. Herein, the presented work describes the working and operational mechanism of the lithium-ion battery. Further, the lithium-ion batteries’ general view and future prospects have also been elaborated.

基于滑模控制的飞轮储能直接功率母线电压控制策略研究

飞轮储能以其瞬时充放电功率大、功率密度高等特点而在储能微电网、大功率UPS中得到广泛应用。飞轮系统可快速输出能量,调节微电网输出频率和电压。然而,储能飞轮在宽速度范围放电时,很难兼顾输出电压的高动态响应和低速稳定性,严重影响了动态性能和放电深度。为提高飞轮储能在放电模式下的动态响应速度和稳定性,提出了一种基于积分滑模控制的固定开关频率直接功率控制策略。该控制策略兼顾了高动态性和飞轮低速稳定性,在负载突变时电压调整率提高了45%,在低速段也能稳定跟随跟定电压,飞轮的利用率提高了7.5%。最后通过仿真分析验证了该控制策略的可行性。

Assessment of water depth change patterns in 120° sharp bend using numerical model

In this study,FLUENT software was employed to simulate the flow pattern and water depth changes in a 120° sharp bend at four discharge rates.To verify the numerical model,a 90° sharp bend was first modeled with a three-dimensional numerical model,and the results were compared with available experimental results.Based on the numerical model validation,a 120° bend was simulated.The results show that the rate of increase of the water depth at the cross-section located 40 cm before the bend,compared with the cross-sections located 40 cm and 80 cm after the bend,decreases with the increase of the normal water depth in the 120° curved channel.Moreover,with increasing normal water depth,the dimensionless water depth change decreases at all cross-sections.At the interior cross-sections of the bend,the transverse water depth slope of the inner half-width is always greater than that of the outer half-width of the channel.Hence,the water depth slope is nonlinear at each crosssection in sharp bends.Two equations reflecting the relationships between the maximum and minimum dimensionless water depths and the normal water depth throughout the channel were obtained.

基于无通讯的微电网储能系统主动SOH协同控制方案

针对传统有功功率-频率(P-f)下垂控制无法实现交流微电网内分布式电池储能系统(DBESS)健康状态(SOH)均衡问题,提出一种基于无通讯的微电网DBESS主动SOH协同控制方案。该方案研究下垂控制调节SOH机理,将DBESS放电深度(DOD)信息加入传统下垂控制,使DBESS能根据SOH状态平移下垂曲线,调节DBESS逆变器输出有功功率,实现DBESS组间SOH协同控制。建立小信号模型分析控制参数对系统稳定性的影响。该方案属于主动控制方案,具有无通讯和分流电阻、造价低的优点。通过仿真模型和实验平台对所提策略的可行性和有效性进行验证。

基于分段削峰的用户侧储能容量优化配置启发式方法

本文对配电网用户侧储能系统优化配置的实用方法进行了研究。模型目标为保持储能系统配置的净收益最大,涉及低储高发电价套利和需量调节收益以及储能系统最优放电深度优化。本文从实际规划应用的目的出发,提出了偏向解析方法的分段削峰启发式模型求解方法,涉及削峰大小和放电深度的枚举,并针对储能配额规律的研究提出了合理的指标设计。算例表明了优化放电深度的意义,以及本文启发式方法的直观、简洁、快速、稳定和实用。

基于SWMM的村镇易涝小区雨水系统改造与优化研究

以某村镇居民小区内涝防治工程为例,应用SWMM雨水管理模型模拟该小区在多个重现期下雨水系统改造效果,分析雨水管道泄流能力、雨水井最大水深、排放口峰值流量等水力特征;考察增加海绵设施后子汇水区径流量、雨水井最大水深和排放口峰值流量等水力特征,并通过雨水井积水深度随时间的变化曲线分析了雨水井累积雨水量。结果表明:无海绵设施的情况下,改造后雨水管网重现期提升至20 a, GQ32雨水管道泄流能力提升2.70%~22.81%,雨水井最大积水深度下降值为0.024~1.651 m, PFK1水流频率下降4.69%~8.02%,PFK2水流频率下降4.72%~8.12%。增加海绵设施的情况下,改造后雨水井积水深度下降0.020~0.298 m, PFK1峰值流量下降0.051~0.144 m3/s, PFK2峰值流量下降0.043~0.143 m3/s;雨水径流削减率随重现期的增加而减少,最高达28.68%。该研究结果可为村镇居民环境优化提供思路和技术支撑。

基于机器视觉辅助测量的精密电火花刻伤方法与系统

传统电火花刻伤机在工作时只对电机动作进行反馈,刀片损耗带来的误差通常靠人为增加进给量进行补偿,难以保证刻槽的形状与尺寸公差。为了更精确地获得刻伤过程中的刀片损耗量,提升闭环控制的电机精度,提出了一种基于机器视觉辅助测量刀片损耗的电火花刻伤方法,并依此设计了一套刻伤系统。实验中使用该系统计算出的刀片损耗量和实际测量值的误差在±5μm以内,同时得到的刻槽实际测量深度与系统计算的刻槽深度的误差在±10μm内。

堰塞坝溃口及洪峰参数模型评估与优化

由滑坡等失稳地质体快速堆积并堵塞河道形成的堰塞坝溃决后会对下游人民生命财产安全造成极大威胁。建立快速准确的溃决参数预测模型,是制定有效防灾减灾措施的必要条件。本文收集了75例包含坝高、库容、溃口峰值流量、坝体冲蚀系数等参数的堰塞坝案例,基于均方根误差、回归相关系数、百分比偏差三个指标对具有代表性的土石坝和堰塞坝参数模型进行评估。通过回归分析建立新的堰塞坝溃口深度预测模型及溃口峰值流量预测模型,将新建模型与现有模型对比,在实际案例中验证了模型的适用性。研究结果表明:现有模型中单参数、双参数及土石坝模型对于堰塞坝溃决参数预测效果不佳,考虑坝体易蚀性的参数模型具有较高准确性,本文所建新模型预测效果有所提升,使用范围更广,预测结果可为堰塞坝的防灾减灾措施提供参考。

基于改进深度残差网络的GIS局部放电在线监测白噪声干扰抑制

针对GIS局部放电(partial discharge,PD)监测中背景白噪声较多、GIS局部放电信号干扰较大的问题,应用改进深度残差网络设计一种新的GIS局部放电在线监测白噪声干扰抑制方法。进行局部放电在线监测中白噪声、局部放电脉冲信号的多尺度特性分析,在局部放电脉冲染噪信号中提取白噪声信号。加入感知损失,设计由生成图像网络与损失网络构成的改进深度残差网络,对白噪声信号波形图像实施超分辨率重建。通过SN-EMD算法提取白噪声信号波形图像的模态域特征。通过构建复小波滤波器组,对模态域特征实施滤波处理,实现GIS局部放电在线监测中的白噪声干扰抑制。实验测试结果表明,设计方法去噪后的信噪比最高可达97.22 dB,干扰抑制前后信号的幅值相对误差最高可达63.20 dB,干扰抑制前后信号相关系数一直大于0.75,完成GIS局部放电在线监测白噪声干扰抑制。

基于粒子群算法的“多站融合”背景下储能站运行策略研究

通过建立数据中心负荷模型、电动汽车充电站负荷模型、储能站充放电模型和5G基站负荷模型,搭建了储能站投资回报率模型。采取两阶段优化方法、粒子群算法对目标函数进行优化,最终得出“多站融合”背景下储能站的最优运行策略。仿真结果表明,典型锂离子电池在合理区间内,峰谷电价差越大,最佳充放电深度越大,在此运行策略下,储能站的经济效益最高。

动力煤绿色低碳分选工艺评价研究

提高动力煤入选率是煤炭清洁开发利用的重要课题,围绕动力煤计价指标发热量,在深度分析了某一原煤粒度组成、高密度可选性、可见矸泥化比、矸石分布特征等数据基础上,确立了动力煤选煤厂的主要功能为深度排矸;干法选煤技术以超高密度分选,回收更多有价值的可燃体,从根本上解决湿法选煤带来的煤泥问题的优势,成为未来存量动力煤选煤厂技改和新增动力煤选煤厂的优选工艺技术。通过研究认为,采用“双效率”评价模式,能够更准确地反映动力煤选煤厂的综合运行效果,逐步转变“动力煤洗选工艺炼焦煤化”的倾向,用分选工艺适度化、精煤产率最大化、煤泥减量化、分选粒级最佳化、工艺流程短平化,实现动力煤绿色低碳分选。

矩形断面恒定非均匀流水面线计算解析

针对无压泄洪隧洞在运行过程中水流流态较复杂的问题,依托青山水库泄洪隧洞改造工程,对无压泄洪隧洞中矩形断面恒定渐变流水面线计算解析进行了数学推导,给出了流程S与始、末端水深之间的解析解;比规范推荐分段试算法更简单便捷,进而通过青山水库泄洪隧洞改造工程1∶30水工模型试验成果对比分析,认为推求的沿程水面线计算解析解合理可靠,为确保泄洪渠及下游河道行洪安全提供了依据,可供类似工程参考应用。

两河口水电站泄洪消能区河道防冲桩设计研究

两河口水电站洞式溢洪道挑坎下泄的水流,对下游泄洪消能区河道的冲刷较严重,需对其进行加固。文章根据实际工程资料对河道和岸坡防冲桩的尺寸及布置进行了设计计算,结合经验公式和规范方法对河道冲刷深度进行了计算,并与实测深度进行了比较。结果表明:规范方法冲刷深度结果偏保守,不利于工程安全性,可以使用经验公式进行施工设计;考虑下泄水流对防冲桩的冲击力和滑坡对其施加的水平力,对防冲桩的直径、长度及布置方式进行了设计和计算,结果表明均能满足工程要求,研究成果可为类似工程提供设计参考。

超声波局部放电检测法在电缆终端中的应用

为研究电缆终端局部放电超声波检测时放电点深度对检测结果的影响,根据检测结果有效分析放电点位置及放电严重程度,采用理论分析、模拟计算、实验室模拟实验、现场应用等方式,结合超声波传播及衰减理论,分析了放电信号在电缆终端表面的沿切向、沿轴向衰减的分布规律,提出了通过迭代及最小二乘法进行局部放电点的源点深度及真实放电水平计算的方法。结果表明:信号量随轴向距离与夹角增大而减小,放电点深度对信号量随放电点与测量点间的轴向距离与夹角的变化率影响较大,放电点深度越小,变化率越大,反之变化率越小。模拟实验与现场应用表明,通过文中的迭代法得到的放电点深度及放电水平与实际基本相符。