Slags containing transition metal(chromium and vanadium)oxides——Conversion from ticking bombs to valuable resources:Collaborative studies between KTH and USTB

As the steel industry expands worldwide,slag dumps with transition metals(especially chromium and vanadium)are becoming more common,posing a serious environmental threat.Understanding the properties of slags containing transition metal oxides,as well as how to use the slags to recover and recycle metal values,is critical.Toward this end,the University of Science and Technology Beijing(USTB)and Royal Institute of Technology(KTH)have been collaborating on slags containing transition metals for decades.The research was carried out from a fundamental viewpoint to get a better understanding of the structure of these slags and their properties,as well as industrial practices.The research focused on the three“R”s,viz.retention,recovery,and recycling.The present paper attempts to highlight some of the important achievements in these joint studies.

基于深度强化学习的机器人轴孔装配策略仿真研究

针对现有轴孔装配方法存在的依赖于精确的接触状态模型、数据采集困难、采样效率低、安全性差等问题,提出了一种基于DRL的机器人轴孔装配策略仿真研究方法。搭建了基于ROSGazebo机器人轴孔装配仿真环境,提出了基于最小二乘法对力/力矩传感器进行重力补偿的方法;基于RL的范式对轴孔装配问题建模,并提出了一种基于SAC(soft actor-critic)算法的机器人轴孔装配方法;通过ROS建立了仿真环境与深度强化学习算法的通信机制。实验结果表明:该算法能够使机器人自主且柔顺地完成轴孔装配任务,并具有较好的泛化性。

考虑频率空间分布特性的虚拟惯量配置优化

高比例电力电子设备并网改变了电力系统频率响应特性,使各节点的频率动态异质化明显,导致低系统惯量、弱频率稳定等问题。电力电子装备提供虚拟惯量支撑是提升频率稳定性的有效途径之一。为改善以新能源为主体的新型电力系统频率响应性能,提出一种考虑新型电力系统频率响应空间分布差异化的虚拟惯量配置优化方法。首先,基于分频器理论,构建反映频率空间分布差异特性的系统频率响应模型。其次,为定量描述惯量分布对节点频率响应性能的影响,提出节点惯量指标与节点动能偏差指标。然后,考虑频率空间分布特性,以优化扰动后各节点的能量不平衡为目标,建立虚拟惯量配置优化模型。最后,通过仿真验证了节点惯量指标有效性以及所提虚拟惯量配置方法对系统节点频率稳定性的提升作用。

考虑攻防博弈的调频辅助服务市场博弈均衡分析

通过不断健全市场交易规则,新型资源逐步参与调频市场,极大提升了调频性能与资源的灵活互济。然而,受制于成本因素,部分新型调频资源的网络安全防护等级较低,黑客可能利用网络安全漏洞破坏调频市场安全。基于此,提出一种考虑攻防博弈的调频市场博弈均衡分析方法。首先,分析考虑篡改防护薄弱型调频资源报价信息的黑客攻击行为;然后,从攻击者角度构建以利益攸关方获利最大化为目标的攻击模型,设计考虑攻防双方主从Stackelberg博弈的调频市场均衡模型;最后,分析基于列和约束生成(column-and-constraint generation,C&CG)算法的调频市场均衡结果,通过对30机组调频市场进行算例分析,容量收益平均偏移度从攻击下的113.89%变为防御后的12.56%,表明防御者可以抑制攻击者造成的市场均衡偏移。

High-rate metal-free MXene microsupercapacitors on paper substrates

MXene is a promising energy storage material for miniaturized microbatteries and microsupercapacitors(MSCs).Despite its superior electrochemical performance,only a few studies have reported MXene-based ultrahigh-rate(>1000 mV s^(−1))on-paper MSCs,mainly due to the reduced electrical conductance of MXene films deposited on paper.Herein,ultrahigh-rate metal-free on-paper MSCs based on heterogeneous MXene/poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)(PEDOT:PSS)-stack electrodes are fabricated through the combination of direct ink writing and femtosecond laser scribing.With a footprint area of only 20 mm^(2),the on-paper MSCs exhibit excellent high-rate capacitive behavior with an areal capacitance of 5.7 mF cm^(−2)and long cycle life(>95%capacitance retention after 10,000 cycles)at a high scan rate of 1000 mV s^(−1),outperforming most of the present on-paper MSCs.Furthermore,the heterogeneous MXene/PEDOT:PSS electrodes can interconnect individual MSCs into metal-free on-paper MSC arrays,which can also be simultaneously charged/discharged at 1000 mV s^(−1),showing scalable capacitive performance.The heterogeneous MXene/PEDOT:PSS stacks are a promising electrode structure for on-paper MSCs to serve as ultrafast miniaturized energy storage components for emerging paper electronics.

Effect of hafnium and molybdenum addition on inclusion characteristics in Co-based dual-phase high-entropy alloys

Specific grades of high-entropy alloys(HEAs)can provide opportunities for optimizing properties toward high-temperature applications.In this work,the Co-based HEA with a chemical composition of Co_(47.5)Cr_(30)Fe_(7.5)Mn_(7.5)Ni_(7.5)(at%)was chosen.The refractory metallic elements hafnium(Hf)and molybdenum(Mo)were added in small amounts(1.5at%)because of their well-known positive effects on high-temperature properties.Inclusion characteristics were comprehensively explored by using a two-dimensional cross-sectional method and extracted by using a three-dimensional electrolytic extraction method.The results revealed that the addition of Hf can reduce Al_(2)O_(3)inclusions and lead to the formation of more stable Hf-rich inclusions as the main phase.Mo addition cannot influence the inclusion type but could influence the inclusion characteristics by affecting the physical parameters of the HEA melt.The calculated coagulation coefficient and collision rate of Al_(2)O_(3)inclusions were higher than those of HfO_(2)inclusions,but the inclusion amount played a larger role in the agglomeration behavior of HfO_(2)and Al_(2)O_(3)inclusions.The impurity level and active elements in HEAs were the crucial factors affecting inclusion formation.

Evolution of nonmetallic inclusions in 80-t 9CrMoCoB large-scale ingots during electroslag remelting process

In combination with theoretical calculations,experiments were conducted to investigate the evolution behavior of nonmetallic inclusions(NMIs)during the manufacture of large-scale heat-resistant steel ingots using 9CrMoCoB heat-resistant steel and CaF_(2)–CaO–Al_(2)O_(3)–SiO_(2)–B_(2)O_(3)electroslag remelting(ESR)-type slag in an 80-t industrial ESR furnace.The main types of NMI in the consumable electrode comprised pure alumina,a multiphase oxide consisting of an Al_(2)O_(3)core and liquid CaO–Al_(2)O_(3)–SiO_(2)–MnO shell,and M_(23)C_(6)carbides with an MnS core.The Al_(2)O_(3)and MnS inclusions had higher precipitation temperatures than the M_(23)C_(6)-type carbide under equilibrium and nonequilibrium solidification processes.Therefore,inclusions can act as nucleation sites for carbide layer precipitation.The ESR process completely removed the liquid CaO–Al_(2)O_(3)–SiO_(2)–MnO oxide and MnS inclusion with a carbide shell,and only the Al_(2)O_(3)inclusions and Al_(2)O_(3)core with a carbide shell occupied the remelted ingot.The M_(23)C_(6)-type carbides in steel were determined as Cr_(23)C_(6)based on the analysis of transmission electron microscopy results.The substitution of Cr with W,Fe,or/and Mo in the Cr_(23)C_(6)lattice caused slight changes in the lattice parameter of the Cr_(23)C_(6)carbide.Therefore,Cr_(21.34)Fe_(1.66)C_(6),(Cr_(19)W_(4)C_(6),Cr_(18.4)Mo_(4.6)C_(6),and Cr_(16)Fe_(5)Mo_(2)C_(6)can match the fraction pattern of Cr_(23)C_(6)carbide.The Al_(2)O_(3)inclusions in the remelted ingot formed due to the reduction of CaO,SiO_(2),and MnO components in the liquid inclusion.The increased Al content in liquid steel or the higher supersaturation degree of Al_(2)O_(3)precipitation in the remelted ingot than that in the electrode can be attributed to the evaporation of CaF_(2)and the increase in CaO content in the ESR-type slag.

Integrating phosphorus management and cropping technology for sustainable maize production

Achieving high maize yields and efficient phosphorus(P)use with limited environmental impacts is one of the greatest challenges in sustainable maize production.Increasing plant density is considered an effective approach for achieving high maize yields.However,the low mobility of P in soils and the scarcity of natural P resources have hindered the development of methods that can simultaneously optimize P use and mitigate the P-related environmental footprint at high plant densities.In this study,meta-analysis and substance flow analysis were conducted to evaluate the effects of different types of mineral P fertilizer on maize yield at varying plant densities and assess the flow of P from rock phosphate mining to P fertilizer use for maize production in China.A significantly higher yield was obtained at higher plant densities than at lower plant densities.The application of single superphosphate,triple super-phosphate,and calcium magnesium phosphate at high plant densities resulted in higher yields and a smaller environmental footprint than the application of diammonium phosphate and monoammonium phosphate.Our scenario analyses suggest that combining the optimal P type and application rate with a high plant density could increase maize yield by 22%.Further,the P resource use efficiency throughout the P supply chain increased by 39%,whereas the P-related environmental footprint decreased by 33%.Thus,simultaneously optimizing the P type and application rate at high plant densities achieved multiple objectives during maize production,indicating that combining P management with cropping techniques is a practical approach to sustainable maize production.These findings offer strategic,synergistic options for achieving sustainable agricultural development.

Precursor engineering enables high-performance all-inorganic CsPbIBr_(2) perovskite solar cells with a record efficiency approaching 13%

All-inorganic CsPbIBr_(2) perovskite has attracted widespread attention in photovoltaic and other optoelectronic devices because of its superior thermal stability.However,the deposition of high-quality solutionprocessed CsPbIBr_(2) perovskite films with large thicknesses remains challenging.Here,we develop a triple-component precursor(TCP) by employing lead bromide,lead iodide,and cesium bromide,to replace the most commonly used double-component precursor(DCP) consisting of lead bromide and cesium iodide.Remarkably,the TCP system significantly increases the solution concentration to 1.3 M,leading to a larger film thickness(~390 nm) and enhanced light absorption.The resultant CsPbIBr_(2) films were evaluated in planar n-i-p structured solar cells,which exhibit a considerably higher optimal photocurrent density of 11.50 mA cm^(-2) in comparison to that of DCP-based devices(10.69 mA cm^(-2)).By adopting an organic surface passivator,the maximum device efficiency using TCP is further boosted to a record efficiency of 12.8% for CsPbIBr_(2) perovskite solar cells.

构网型变流器稳定性研究综述

相比目前常用的跟网型变流器,构网型变流器具有同步电压源特性,可以有效提升电力电子化的新型电力系统的稳定性,因而近年来受到了广泛的关注。为了给构网型变流器大规模工程应用提供理论基础支撑,需要在不同电网强度,不同电网扰动形式下对构网型变流器进行完整的稳定性分析。该文拟从稳态工作点的存在性,小信号稳定和大信号稳定3个层面,对现有构网型变流器稳定性分析成果进行系统的梳理和总结。在此基础上进一步归纳提升构网型变流器稳定性的控制方法。最后,总结数个关于构网型变流器稳定性分析和控制的研究方向,为进一步深入研究提供参考。

考虑交通参与者的城市交叉口车速预测模型

为了提高车辆在城市交叉口自由行驶状态下的车速预测性能,提出一种考虑本车与其他交通参与者交互特性的车速预测新方法.首先,提出一种车辆目标细分方法来区分其他车辆相对于本车的行驶方向,并应用目标检测算法YOLOv5识别潜在的交通冲突和弱势交通参与者;然后,将识别的交通参与者信息与历史车速信息相结合,建立基于长短期记忆网络的车速预测模型,在左转、右转以及直行3种不同的驾驶场景下验证交通参与者信息对于提高车速预测性能的有效性.结果表明:与仅以历史车速为输入的基准模型相比,考虑交通参与者的车速预测模型表现出更好的性能,其在很大程度上解决了预测模型在一个预测时域内精度逐渐下降的问题,并对城市交叉口的复杂交通环境表现出更强的适应性.

考虑需求响应的互联交直流混合微电网的分布式经济调度模型

交直流混合微网能够高效集成分布式电源和柔性负荷,开放共享的互联系统能够通过功率共享机制进一步提高多微网的可靠性和经济性。提出了考虑需求响应的互联交直流混合微电网的分布式经济调度模型。对于单个微网,建立了考虑需求响应的优化模型来降低自身的运营成本,并通过添加备用容量约束来应对微网中的不确定性。对于整个互联系统,直流网络通过协调各微网的边界信息来优化潮流分布,降低网损。整个优化问题以分布式的方式进行求解,微网内部的负荷资源被充分协调,各微网仅需提供有限的边界信息,用户隐私被充分保护。算例结果证明了所提调度模型的有效性。

Rock mass response for lined rock caverns subjected to high internal gas pressure

The storage of hydrogen gas in underground lined rock caverns(LRCs)enables the implementation of the first fossil-free steelmaking process to meet the large demand for crude steel.Predicting the response of rock mass is important to ensure that gas leakage due to rupture of the steel lining does not occur.Analytical and numerical models can be used to estimate the rock mass response to high internal pressure;however,the fitness of these models under different in situ stress conditions and cavern shapes has not been studied.In this paper,the suitability of analytical and numerical models to estimate the maximum cavern wall tangential strain under high internal pressure is studied.The analytical model is derived in detail and finite element(FE)models considering both two-dimensional(2D)and three-dimensional(3D)geometries are presented.These models are verified with field measurements from the LRC in Skallen,southwestern Sweden.The analytical model is inexpensive to implement and gives good results for isotropic in situ stress conditions and large cavern heights.For the case of anisotropic horizontal in situ stresses,as the conditions in Skallen,the 3D FE model is the best approach.

基于边缘计算的软件定义云制造和柔性资源调度研究

本研究的重点是在云制造环境中实现快速重构、实现灵活的资源调度、开发资源潜力以应对各种变化。因此,本文首先提出了一种新的基于云和软件定义网络(SDN)的制造模型——软件定义云制造(SDCM),该模型将控制逻辑从自动化硬件转移到软件上。这种转变意义重大,因为软件可以充当制造系统的“大脑”,并且可以轻松更改或更新以支持快速系统重新配置、运营和演进。随后,边缘计算被引入,以接近终端的计算和存储能力来补充云。另一个关键问题是管理由不同服务质量(QoS)要求的大量物联网(IoT)数据传输而导致的严重网络拥塞。基于SDCM的虚拟化和灵活的网络能力,本研究形式化了面向复杂制造任务集的时间敏感性数据流量控制问题,并考虑了子任务分配和数据路由路径选择。为了解决这一优化问题,提出了一种将遗传算法(GA)、Dijkstra最短路径算法和排队算法相结合的方法。实验结果表明,该方法能有效地防止网络拥塞,减少SDCM中的总通信延迟。

Effect of gas blowing nozzle angle on multiphase flow and mass transfer during RH refining process

A three-dimensional mathematical model was developed to investigate the effect of gas blowing nozzle angles on multiphase flow,circulation flow rate,and mixing time during Ruhrstahl-Heraeus(RH) refining process.Also,a water model with a geometric scale of 1:4 from an industrial RH furnace of 260 t was built up,and measurements were carried out to validate the mathematical model.The results show that,with a conventional gas blowing nozzle and the total gas flow rate of 40 L·min^(-1),the mixing time predicted by the mathematical model agrees well with the measured values.The deviations between the model predictions and the measured values are in the range of about 1.3%–7.3% at the selected three monitoring locations,where the mixing time was defined as the required time when the dimensionless concentration is within 3% deviation from the bath averaged value.In addition,the circulation flow rate was 9 kg·s^(-1).When the gas blowing nozzle was horizontally rotated by either 30° or 45°,the circulation flow rate was found to be increased by about 15% compared to a conventional nozzle,due to the rotational flow formed in the up-snorkel.Furthermore,the mixing time at the monitoring point 1,2,and 3 was shortened by around 21.3%,28.2%,and 12.3%,respectively.With the nozzle angle of 30° and 45°,the averaged residence time of 128 bubbles in liquid was increased by around 33.3%.

Effect of rock joints on lined rock caverns subjected to high internal gaspressure

The storage of hydrogen gas in lined rock caverns(LRCs)may enable the implementation of the firstlarge-scale fossil-free steelmaking process in Sweden,but filling such storage causes joints in the rockmass to open,concentrating strains in the lining.The structural interaction between the LRC componentsmust be able to reduce the strain concentration in the sealing steel lining;however,this interaction iscomplex and difficult to predict with analytical methods.In this paper,the strain concentration in LRCsfrom the opening of rock joints is studied using finite element(FE)analyses,where the large-and small-scale deformation behaviors of the LRC are coupled.The model also includes concrete crack initiation anddevelopment with increasing gas pressure and rock joint width.The interaction between the jointed rockmass and the reinforced concrete,the sliding layer,and the steel lining is demonstrated.The results showthat the rock mass quality and the spacing of the rock joints have the greatest influence on the straindistributions in the steel lining.The largest effect of rock joints on the maximum strains in the steellining was observed for geological conditions of“good”quality rock masses.

自旋半经典朗之万方程一般形式的探讨

有限温度下自旋半经典系统的随机动力学行为通常由随机Landau-Lifshitz方程描述.本文在朗之万随机微分方程的框架内,推导出有效朗之万方程的一般形式,及其对应的Fokker-Planck方程的表达式.该有效朗之万方程能正确描述正则系综下自旋半经典系统的统计物理性质,并且在阻尼项和随机项消失时能退化到自旋半经典运动方程,因此是随机Landau-Lifshitz方程的一种推广.在笛卡尔坐标系和球坐标系中,分别给出有效朗之万方程的一般形式和对应的Fokker-Planck方程的显式表达式.在球坐标系中,讨论了朗之万方程中的纵场效应,并从方程采取的形式中给出是否包含纵场效应的判断依据.最后,有效朗之万方程在一个单自旋、定值外磁场的体系中进行应用.对方程采取特定的形式进行简便的求解,并成功得到玻尔兹曼稳定分布,该结果也检验了有效朗之万方程的准确性.

Improving rail vehicle dynamic performance with active suspension

Today,it is difficult to further improve the dynamic performance of rail vehicles with conventional passive suspension.Also,simplified vehicle respectively running gear layouts that significantly could reduce vehicle weights are difficult to realize with modern requirements on passenger vibration comfort and wheel and rail wear.Active suspension is a powerful technology that can improve the vehicle dynamic performance and make simplified vehicle concepts possible.The KTH Railway group has,together with external partners,investigated active suspensions both numerically and experimentally for 15 years.The paper provides a summary of the activities and the most important findings.One major project carried out in close collaboration with the vehicle manufacturer Bombardier and the Swedish Transport Administration was the Green Train project,where a 2-car EMU test bench was used to demonstrate different active technologies.In ongoing projects,a concept of single axle-single suspension running gear is developed with active suspension both for comfort improvement and reduced wheel wear in curves.The results from on-track tests in the Green Train project were so good that the technology is now implemented in commercial trains and the simulation results for the single-axle running gear are very promising.

Modelling erosion of a single rock block using a coupled CFD-DEM approach

Rock block removal is the prevalent physical mechanism for rock erosion and could affect the stability of dam foundations and spillways.Despite this,understanding of block removal is still inadequate because of the complex interactions among block characteristics,hydraulic forces,and erosive processes acting on the block.Herein,based on a previously conducted physical experiment of erosion of a single rock block,the removal processes of two different protruding blocks are represented by a coupled computational fluid dynamics-discrete element model(CFD-DEM)approach under varied flow conditions.Additionally,the blocks could be rotated with respect to the flow direction to consider the effect of the discontinuity orientation on the block removal process.Simulation results visualize the entire block removal process.The simulations reproduce the effects of the discontinuity orientation on the critical flow velocity inducing block incipient motion and the trajectory of the block motion observed in the physical experiments.The numerical results present a similar tendency of the critical velocities at different discontinuity orientations but have slightly lower values.The trajectory of the block in the simulations fits well with the experimental measurements.The relationship between the dimensionless critical shear stress and discontinuity orientation observed from the simulations shows that the effect of block protrusion becomes more dominant on the block incipient motion with the increase of relative protrusion height.To our knowledge,this present study is the first attempt to use the coupled finite volume method(FVM)-DEM approach for modelling the interaction behavior between the block and the flowing water so that the block removal process can be reproduced and analyzed.

面向工业互联网平台的二维制造服务协作优化

工业互联网平台被公认为智能制造的必要推动者,使物理制造资源得以虚拟化,并允许资源以服务的形式进行协作。作为平台的核心功能,制造服务协作优化致力于为制造任务提供高质量的服务协作解决方案。这种优化与任务的功能和数量要求密不可分,在编排服务时必须满足这些要求。然而,现有的制造服务协作优化方法主要关注服务之间针对功能需求的横向协作,很少考虑纵向协作来覆盖所需的数量。为了解决这一差距,本文提出了一种结合功能和数量协作的二维服务协作方法。首先,提出了一种描述服务的多粒度制造服务建模方法。在此基础上,建立了二维制造服务协同优化模型。在垂直维度上,多个功能等效的服务组成一个服务集群来完成一个子任务;在水平维度上,互补服务集群协作完成整个任务。服务的选择和所选服务的金额分配是模型中的关键问题。为了解决这个问题,设计了一种具有多个局部搜索算子的多目标模因算法。将该算法嵌入竞争机制来动态调整本地搜索算子的选择概率。实验结果表明,与常用算法相比,该算法在收敛性、解质量和综合度量方面具有优势。