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A Novel Serial Hybrid Three-level NPC Topology for Multi-MW Medium Voltage Wind Power Converters 被引量:5
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作者 CHEN Gen WANG Yong CAI Xu 《中国电机工程学报》 EI CSCD 北大核心 2013年第9期I0007-I0007,共1页
提出一种新型的串联混合三电平中点钳位(neutralpoint clamped,NPC)拓扑,该拓扑是基于传统三电平NPC拓扑的改进和优化,引入大功率IGBT的串联应用。该新型拓扑中,桥臂的两个外管分别用两个低压IGBT串联,两个内管均用高压IGBT。在多兆... 提出一种新型的串联混合三电平中点钳位(neutralpoint clamped,NPC)拓扑,该拓扑是基于传统三电平NPC拓扑的改进和优化,引入大功率IGBT的串联应用。该新型拓扑中,桥臂的两个外管分别用两个低压IGBT串联,两个内管均用高压IGBT。在多兆瓦级中压风电变流器中,大功率IGBT的开关损耗很大,从而限制了开关频率。提出的新型拓扑通过低压IGBT的串联来减小功率器件的损耗,从而提高开关频率,同时可减小输出滤波器的尺寸。通过传统三电平拓扑和新型串联混合三电平拓扑IGBT损耗的对比,说明新拓扑的优势。通过改变门极驱动电阻实现串联IGBT的均压,对新拓扑的应用具有重大意义。最后通过新拓扑的单相样机验证新拓扑的正确性和可行性。 展开更多
关键词 电压转换器 拓扑结构 风力发电 中压 NPC 三电平 混合 串联
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Mathematical Modeling of Porous Medium for Sound Absorption Simulations: Application of Multi-Scales and Homogenization 被引量:2
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作者 Allen Teagle-Hernandez Ortwin Ohtmer Duyen Nguyen 《Journal of Applied Mathematics and Physics》 2018年第12期2705-2717,共13页
The modeling of porous medium has many applications whose techniques can be used in the fields of automotive, aerospace, oil exploration, and biomedical. This work concentrates on the Noise and Vibration (NV) developm... The modeling of porous medium has many applications whose techniques can be used in the fields of automotive, aerospace, oil exploration, and biomedical. This work concentrates on the Noise and Vibration (NV) development of automotive interiors but the ideas can be translated to the aforementioned areas. The NV development requires the setting of NV targets at dif-ferent levels. These targets are then translated to TL (Transmission Loss), IL (Insertion Loss), and Alpha (absorption) performance. Therefore, the ability to manage an efficient product development cycle, that entails analyzing vibro-acoustic environments, hinges on the premise that accurate TL, IL, or Alpha values pertaining to the different multi-layered porous materials can be calculated. Thus, there is a need to have a thorough understanding of the physics behind the energy dissipating mechanism that includes the effects of the fluid meandering through the pores of the material. The goal of this series is to model the acoustic and dynamic coupling via multi-scale and homogenizations techniques, thus subsequently understand where to incorporate the concepts of dynamic tortuosity, viscous and thermal permeability, as well as viscous and thermal lengths. This study will allow the ability to get a better understanding of the underlying processes and also provides tools to create practical concepts for determining the coefficients of the macroscopic equations. This will assist in attaining novel ideas for NV absorption and insulation. 展开更多
关键词 POROUS medium multi-SCALE HOMOGENIZATION Fluid Structure Interaction
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Multi-Period Optimal Distribution Model of Energy Medium and Its Application 被引量:3
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作者 ZHANG Qi TI Wei +2 位作者 CAI Jiu-ju DU Tao WANG Ai-hua 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2011年第8期37-41,共5页
A mathematical model of optimal energy medium distribution in steelmaking process is formulated. In this model, three kinds of important energy mediums including byproduct gases, steam and electricity are considered, ... A mathematical model of optimal energy medium distribution in steelmaking process is formulated. In this model, three kinds of important energy mediums including byproduct gases, steam and electricity are considered, and the objective function accounts for both the change of generation and consumption of the byproduct gases and the demand of low (or middle) pressure steam and electricity for each period to maximize the benefit of products cost and minimize the consumption of energy. The results indicate that the optimal distribution scheme of byproduct gases, middle pressure steam, low pressure steam and electricity is achieved and case study shows that 6% of operation cost is reduced by using the proposed model comparing with the previous model. 展开更多
关键词 energy medium byproduct gas multi-PERIOD optimal distribution energy saving
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PARAMETRIC MATCHING SELECTION OF MULTI-MEDIUM COUPLING SHOCK ABSORBER
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作者 YANG Ping DING Jianning YANG Jichang LI Changsheng FAN Zhen LIN Zhiyong 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2006年第1期124-127,共4页
To achieve the dual demand of resisting violent impact and attenuating vibration in vibration-impact-safety of protection for precision equipment such as MEMS packaging system, a theo- retical mathematical model of mu... To achieve the dual demand of resisting violent impact and attenuating vibration in vibration-impact-safety of protection for precision equipment such as MEMS packaging system, a theo- retical mathematical model of multi-medium coupling shock absorber is presented. The coupling of quadratic damping, linear damping, Coulomb damping and nonlinear spring are considered in the model. The approximate theoretical calculating formulae are deduced by introducing transformation-tactics. The contrasts between the analytical results and numerical integration results are developed. The resisting impact characteristics of the model are also analyzed in progress. In the meantime, the optimum model of the parameters matching selection for design of the shock absorber is built. The example design is illustrated to confirm the validity of the modeling method and the theoretical solution. 展开更多
关键词 multi-damping medium Shock absorber Model Parametric matching selection Resisting impact and attenuating vibration
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铁线莲品种‘Multi-Blue’不定根的诱导培养及其发生过程的解剖学观察 被引量:9
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作者 张启香 胡恒康 方炎明 《植物资源与环境学报》 CAS CSCD 2010年第1期80-85,共6页
对适宜于铁线莲品种‘Multi-Blue’(Clematis‘Multi-Blue’)不定芽生根培养的基本培养基进行了筛选,并采用L9(32)正交实验设计对生根培养基中NAA和IBA质量浓度进行了比较分析,对不定根形成过程中解剖结构的变化也进行了观察。接种在1/... 对适宜于铁线莲品种‘Multi-Blue’(Clematis‘Multi-Blue’)不定芽生根培养的基本培养基进行了筛选,并采用L9(32)正交实验设计对生根培养基中NAA和IBA质量浓度进行了比较分析,对不定根形成过程中解剖结构的变化也进行了观察。接种在1/2MS培养基上的铁线莲品种‘Multi-Blue’不定芽的生根率极显著高于改良1/2MS、MS和WPM培养基(P<0.01),生根率达66.97%;在1/2MS培养基中添加0.05 mg.L-1NAA,不定芽的生根效果最好,生根率达69.34%,极显著高于其他处理组(P<0.01)。研究结果表明,添加0.05 mg.L-1NAA的1/2MS培养基(含30 g.L-1蔗糖和8 g.L-1琼脂,pH5.8)为铁线莲品种‘Multi-Blue’不定芽生根培养的最佳培养基。在不定芽的茎横切面上未见潜伏根原基存在;而在接种约1周后,不定芽茎基部皮层的薄壁细胞逐渐恢复分生能力,出现胞质变浓、核质增加、液泡缩小及细胞排列紧密等变化,细胞开始分裂并形成分生细胞团;接种后约2周,根原基发端细胞不断分裂并逐渐形成体积较小、染色较深的一群分生细胞,并出现明显的分层结构;接种后约3周,细胞继续进行平周分裂和垂周分裂,并分化出球形或楔形的不定根根原基;根原基在皮层中常发生弯曲或分支,且皮层处的不定根加粗生长,最终突破皮孔并形成独立的不定根。观察结果表明,铁线莲品种‘Multi-Blue’不定芽基部形成的不定根根原基为诱生根原基。 展开更多
关键词 铁线莲品种'multi-Blue’ 不定根 基本培养基类型 NAA 解剖结构
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面向服务的Multi-Agent系统
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作者 沈记全 米爱中 涂序彦 《计算机工程与科学》 CSCD 2007年第10期139-141,共3页
本文以服务为中心,从面向服务的系统架构、中介服务协作机制、理性化的协商机制和智能交互等四个方面去建立开放、动态、面向服务的多Agent系统,以提高Agent的社会性智能。
关键词 多AGENT 面向服务 中介服务 理性协商 智能交互
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Performance Evaluation for Medium Voltage MIMO-OFDM Power Line Communication System 被引量:11
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作者 Yingxue Li Min Zhang +3 位作者 Wenguang Zhu Mengyuan Cheng Cheng Zhou Yongpeng Wu 《China Communications》 SCIE CSCD 2020年第1期151-162,共12页
Power line communication(PLC)provides intelligent electrical functions such as power quality measurement,fault surveys,and remote control of electrical network.Most of research works have been done in low voltage(LV)s... Power line communication(PLC)provides intelligent electrical functions such as power quality measurement,fault surveys,and remote control of electrical network.Most of research works have been done in low voltage(LV)scenario due to the fast development of in-home PLC.The aim of this paper is to evaluate the link-level performance of a medium voltage(MV)MIMO-OFDM communication system based on transmission link under underground power line channel.The MIMO channel is modeled as a modified multipath model in the presence of impulsive noise and background noise.We first perform a measurement on the practical MV MIMO channel parameters for a section of buried cable of 1 km long in Ganzhou city,Jiangxi province,China.Based on the measured channel,we design the frame structure based on an IEEE standard for broadband over power line networks[1]to support MV MIMO-OFDM transmission.According to designed frame structure,we design an encoder and a decoder for a dual binary tail-biting turbo code and optimize some key decoder parameters for low bit error rate performance.Finally,the link-level performance for both spatial multiplexing and spatial diversity are evaluated.Numeral results show that MV MIMO-OFDM is a promising approach to provide both high data rate and link reliability for PLC. 展开更多
关键词 power line communication(PLC) MIMO-OFDM multi-conductor medium voltage underground cables turbo code
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In-plane dynamic Green's functions for inclined and uniformly distributed loads in a multi-layered transversely isotropic half-space 被引量:4
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作者 Ba Zhenning Kang Zeqing Liang Jianwen 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2018年第2期293-309,共17页
The dynamic stiffness method combined with the Fourier transform is utilized to derive the in-plane Green’s functions for inclined and uniformly distributed loads in a multi-layered transversely isotropic(TI)half-s... The dynamic stiffness method combined with the Fourier transform is utilized to derive the in-plane Green’s functions for inclined and uniformly distributed loads in a multi-layered transversely isotropic(TI)half-space.The loaded layer is fixed to obtain solutions restricted in it and the corresponding reactions forces,which are then applied to the total system with the opposite sign.By adding solutions restricted in the loaded layer to solutions from the reaction forces,the global solutions in the wavenumber domain are obtained,and the dynamic Green’s functions in the space domain are recovered by the inverse Fourier transform.The presented formulations can be reduced to the isotropic case developed by Wolf(1985),and are further verified by comparisons with existing solutions in a uniform isotropic as well as a layered TI halfspace subjected to horizontally distributed loads which are special cases of the more general problem addressed.The deduced Green’s functions,in conjunction with boundary element methods,will lead to significant advances in the investigation of a variety of wave scattering,wave radiation and soil-structure interaction problems in a layered TI site.Selected numerical results are given to investigate the influence of material anisotropy,frequency of excitation,inclination angle and layered on the responses of displacement and stress,and some conclusions are drawn. 展开更多
关键词 Green's functions transversely isotropic medium multi-layered half-space stiffness method dynamic response
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RECONSTRUCTION OF ONE DIMENSIONAL MULTI-LAYERED MEDIA BY USING A TIME DOMAIN SIGNAL FLOW GRAPH TECHNIQUE 被引量:1
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作者 崔铁军 梁昌洪 《Journal of Electronics(China)》 1993年第2期162-169,共8页
A novel inverse scattering method to reconstruct the permittivity profile of one-dimensional multi-layered media is proposed in this paper.Based on the equivalent network ofthe medium,a concept of time domain signal f... A novel inverse scattering method to reconstruct the permittivity profile of one-dimensional multi-layered media is proposed in this paper.Based on the equivalent network ofthe medium,a concept of time domain signal flow graph and its basic principles are introduced,from which the reflection coefficient of the medium in time domain can be shown to be a series ofDirac δ-functions(pulse responses).In terms of the pulse responses,we will reconstruct both thepermittivity and the thickness of each layer will accurately be reconstructed.Numerical examplesverify the applicability of this 展开更多
关键词 multi-layered medium Reconstruct PERMITTIVITY profile INVERSE SCATTERING Time DOMAIN signal flow GRAPH
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无线信道数字孪生关键技术现状及展望 被引量:2
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作者 官科 张美文 +9 位作者 何丹萍 艾渤 刘婷 王熙平 魏垚 赵旭 卢斌 窦建武 王欣晖 钟章队 《电波科学学报》 北大核心 2025年第5期789-799,共11页
随着6G的逐步推进,无线信道数字孪生技术作为未来网络演进的关键技术之一,受到了广泛的关注。本文综述了无线信道数字孪生技术的背景、系统架构及关键技术,并展望了未来的发展方向。首先,介绍了无线信道数字孪生技术的发展背景与需求、... 随着6G的逐步推进,无线信道数字孪生技术作为未来网络演进的关键技术之一,受到了广泛的关注。本文综述了无线信道数字孪生技术的背景、系统架构及关键技术,并展望了未来的发展方向。首先,介绍了无线信道数字孪生技术的发展背景与需求、系统特点以及研究进展;然后,详细讨论了复杂环境多介质电磁参数获取、高性能射线追踪仿真技术和模型-数据双驱动的混合信道建模等关键技术;最后,对无线信道数字孪生技术在6G时代的发展做出展望,并总结了潜在的标准化工作。无线信道数字孪生技术通过构建无线信道的虚拟孪生体,提供了无线信道特性建模及其效应预测能力,对6G及未来通信系统的发展具有重要意义。 展开更多
关键词 6G 无线信道 数字孪生 射线追踪 混合信道建模 介质电磁参数
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基于模型耦合的多介质复合材料导热系数预测 被引量:1
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作者 马令勇 李昕瑶 +2 位作者 王志国 刘洋 李清 《工程热物理学报》 北大核心 2025年第8期2660-2668,共9页
提升建筑材料储热性能及其对太阳能的利用率是实现建筑节能的有效方法。本文针对一种多介质复合的建筑储能新材料进行研究,提出了适用于该种材料的导热系数的计算模型,并通过材料制备及实验对计算模型进行对比分析。研究发现,通过广义... 提升建筑材料储热性能及其对太阳能的利用率是实现建筑节能的有效方法。本文针对一种多介质复合的建筑储能新材料进行研究,提出了适用于该种材料的导热系数的计算模型,并通过材料制备及实验对计算模型进行对比分析。研究发现,通过广义自洽模型与等效介质理论模型耦合最终推导出的等效导热系数符合实验测试和串并联模型得出的结果,适用于预测该种结构的材料等效导热系数。随着相变玻璃珠含量增加,材料整体的导热系数越小,储热性能越好,过程呈线性变化趋势。 展开更多
关键词 多介质复合材料 等效导热系数 广义自洽模型 等效介质理论模型
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Grid-connected Multilevel Topology for HVDC Offshore Wind Farm Based on MFT
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作者 Firas Obeidat XU Lie LI Yong-dong 《电力电子技术》 CSCD 北大核心 2013年第6期29-32,共4页
This paper presents a new topology to connect high voltage direct current(HVDC) offshore wind farm into the grid.The offshore part consists of five units,each unit contains permanent magnet synchronous generator(PMSG)... This paper presents a new topology to connect high voltage direct current(HVDC) offshore wind farm into the grid.The offshore part consists of five units,each unit contains permanent magnet synchronous generator(PMSG) connected to three-phase/three-phase matrix converter to control the generator speed by using a maximum power point tracking(MPPT) control.The offshore platform consists of a three-phase medium frequency transformer(MFT) and a modular multi-level converter(MMC).The primary of each phase of the transformer connected to one phase from each unit.The secondary of the transformer connected to MMC to get HVDC.The HVDC cable will be used to transfer power from the offshore side to the on-shore side.Five-level MMC is used in the onshore side to control the DC voltage and to connect the offshore wind farm into the grid by converting the HVDC to high voltage alternative current(HVAC). 展开更多
关键词 电子技术 电力发展 工程设计 产品技术
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Mathematical Modeling of Porous Medium for Sound Absorption Simulations II: Wave Propagation and Interface Conditions
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作者 Allen Teagle-Hernandez Ortwin Ohtmer Duyen Nguyen 《Journal of Applied Mathematics and Physics》 2019年第11期2780-2795,共16页
The application of porous medium has a myriad of applications in different industries: automotive, aerospace, civil (commercial, residential), environmental noise control, and biomedical. In the past, design questions... The application of porous medium has a myriad of applications in different industries: automotive, aerospace, civil (commercial, residential), environmental noise control, and biomedical. In the past, design questions involving porous material were addressed with seat-of-the-pants decisions that led to multiple/iterative prototypes and experiments that were costly and time consuming. The objective, in this series of publications pertaining to porous medium, is to establish tools that will lead to effective and accurate simulations involving porous medium. In this third installment of this series the focus is on establishing the constitutive equations using tensors and then applying Transfer Matrix Method (TMM) to calculate diffuse field Transmission Loss (TL) across structures that comprises of layers of different porous medium. The constitutive equations are obtained by relating information regarding the micro-structure make-up to macro level properties. In order to apply the TMM, the equations for wave propagation across different mediums need to be developed and in turn represent these propagation properties in a matrix format. Additionally, the boundary condition between each layer type is defined in order to ensure numerical stability. The author’s current research effort is running simulations for the automotive industry to predict NVH environments. Therefore, TL calculations pertaining to the materials that are utilized in the interior of automobiles are used, in this paper, as a test bed for the developed analytical tools. Case in point, the TL for a multi-layered material consisting of one panel and two different layers of foam is calculated and compared to experimental data. Future publication goals will be to apply these tools in the biomedical field;an example will be to model and run simulations of different organs like the liver and lungs that are po-rous in nature. 展开更多
关键词 POROUS medium multi-SCALE HOMOGENIZATION Fluid Structure Interaction
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高分辨率捕捉强间断多介质流场的伪弧长方法
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作者 李坤 马天宝 王渊芃 《兵工学报》 北大核心 2025年第10期334-347,共14页
可压缩多介质气液两相流中,介质热力学差异导致界面区域呈现强非线性波系干涉,显著增加数值模拟难度。尤其在双曲型守恒律方程框架下,流场易形成激波、接触间断和稀疏波等奇异结构,对算法精度、间断捕捉能力及稳定性提出更高要求。为此... 可压缩多介质气液两相流中,介质热力学差异导致界面区域呈现强非线性波系干涉,显著增加数值模拟难度。尤其在双曲型守恒律方程框架下,流场易形成激波、接触间断和稀疏波等奇异结构,对算法精度、间断捕捉能力及稳定性提出更高要求。为此,构建了一种面向多介质气液两相流场的高精度伪弧长方法,通过引入弧长参数将方程映射至正交弧长空间,缓解强间断导致的数值奇异性,并引入高阶重构格式保证解的精度。为精准刻画界面动力学行为,提出基于弧长空间的符号距离函数演化机制,并结合真实虚拟流体方法严格定义边界条件,确保界面物理量连续性。数值结果表明,该方法具备对强间断及复杂波系结构的高分辨率解析能力。 展开更多
关键词 多介质 双曲型守恒律方程 伪弧长方法 非线性 强间断
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MEDIUM-RANGE OSCILLATION OF METEOROLOGICAL ELEMENTS AT GREAT WALL STATION,ANTARCTICA
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作者 Lu Longhua Bian Lingen Zhang Yongping Polar Meteorological Laboratory, Academy of Meteorological Sciences, Beijing 100081 《Chinese Journal of Polar Science》 1990年第1期36-48,共13页
A method of multi-spectral analysis is used to study the spectral characteristics of surface and upper-level meteorological elements over the Great Wall Station (62°12'S, 58°57'W), Antarctica and the... A method of multi-spectral analysis is used to study the spectral characteristics of surface and upper-level meteorological elements over the Great Wall Station (62°12'S, 58°57'W), Antarctica and their phasecorrelation, propagation of mean oscillation at 500hPa level in the Southern Hemisphere and their corresponding synoptic sense. the results are summed up as follows: 1. Over the sub-Antatctic zone, as in the Northern Hemisphere there generally exist quasi-weekly oscillation and quasi-biweekly oscillation. In different seasons the oscillations of meteorological elements are different: in winter season quasi-biweekly oscillation is dominant, while in summer season quasi-weekly oscillation is dominant. 2. From the Earth's surface to the lower stratosphere there is a distinct quasi-weekly oscillation at each isobaric surface, but the most intense oscillation appears at 200-300hPa, and the oscillations of height and temperature are propagated downward. 3. Both in winter and summer seasons the quasi-biweekly oscillation are propagated from west to east, and the mean velocity of its propagation is about 7-17 longtitude / day. 4. The quasi-biweekly oscillation and the quasi-weekly oscillation over the sub - Antarctic zone are closely related to the activity and intensity variation of polar vortex at 500hPa, while at 1000hPa they reflect an interaction between the circumpolar depression and the sub-tropical high. The quasi-biweekly oscillation may be a reflection of inherent oscillation of the polar vortex, where as the quasi-weekly oscillation is a result of forced oscillation by external disturbance.A large number of calculations and analysis made reveals the features of medium-range oscillation over the sub-Antarctic zone. The results are of significance for understanding the behaviour of synoptic dynamics and making the weather forecast.This work is supported by National Committee for Antarctic Research. 展开更多
关键词 Antarctic Great Wall Station Meteorological elements multi-spectral analysis method medium-range oscillation Polar vortex.
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计及多场景因素的钢铁企业多介质能源计划优化研究
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作者 吴定会 张子恒 范俊岩 《控制工程》 北大核心 2025年第1期12-20,共9页
钢铁企业的生产运行受能源制约,制定能源计划是钢铁企业实现降低生产成本和节能降耗的重要途径。煤气、蒸汽、电力是钢铁生产能源系统中的主要能源。针对多能源介质间存在的多约束、强耦合、非线性的特点和分时电价、检修减产的不同场... 钢铁企业的生产运行受能源制约,制定能源计划是钢铁企业实现降低生产成本和节能降耗的重要途径。煤气、蒸汽、电力是钢铁生产能源系统中的主要能源。针对多能源介质间存在的多约束、强耦合、非线性的特点和分时电价、检修减产的不同场景因素,以生产成本最低为目标函数,建立了针对钢铁生产能源系统的耦合优化模型,并提出了一种改进差分变异烟花算法(improved differential mutation fireworks algorithm,IDM-FWA)。根据钢铁企业的实际运行数据进行仿真分析,仿真结果表明,基于IDM-FWA得到的日内24 h能源计划能够在保证产量不变的同时降低生产成本,实现节能降耗。 展开更多
关键词 多介质能源 能源计划 烟花算法 多场景
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Further Stabilization and Power Density Improvement of Stack-Type Thermoelectric Power Generating Module with Biphasic Medium by Using Various Flexible Metals as Electrodes
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作者 Seiichi Deguchi Shoichiro Imaizumi +5 位作者 Hajime Arimura Keisuke Sawada Noriyuki Kobayashi Norifumi Isu Kenji Sakai Kentaro Kimoto 《Journal of Power and Energy Engineering》 2018年第11期78-86,共9页
In order to realize further stability of a stack-type thermoelectric power generating module (i.e. no electrical connections inside), flexible materials of metal springs and/or rods having restoring forces were instal... In order to realize further stability of a stack-type thermoelectric power generating module (i.e. no electrical connections inside), flexible materials of metal springs and/or rods having restoring forces were installed between lower-temperature-sides of thermoelectric elements. These flexible materials were expected to play three important roles of interpolating different thermal expansions of the module components, enlarging heat removal area and penetration of any media through themselves. Then, a low-boiling-point medium (i.e. NOVEC manufactured by 3M Japan Ltd.) was also applied for a high-speed direct heat removal via its phase change from the lower-temperature-sides of the thermoelectric elements in the proposing stack-type thermoelectric power generating module. No electrical disconnections inside the module were confirmed for more than 9 years of use, indicating further module stability. The power generating density was improved to about 120 mW·m-2 with SUS304 springs having 0.7 mm diameter. Increasing power generating density can be expected in terms of suitable selection of flexible metal with high Vickers hardness, cavities control on the spring surface, more vigorous multiphase flow with adding powders to the medium and optimization of the module configurations according to numerical simulations. 展开更多
关键词 Thermoelectric Power Generation Stack-Type MODULE FLEXIBLE Section BIPHASIC medium Phase Change multi-Phase Flow Heat Transfer Enhancement MODULE STABILIZATION
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多材料介质中无压渗流问题的离散元求解
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作者 吕学科 《内蒙古工业大学学报(自然科学版)》 2025年第4期362-369,共8页
为了更好地模拟多材料介质无压渗流问题,提出了一种基于颗粒离散元的离散颗粒渗流模型(discrete seepage element model,DSEM)。该模型将连续介质离散化为密集堆积的颗粒系统,赋予颗粒流体性质,并通过颗粒间压力差模拟渗流过程。DSEM模... 为了更好地模拟多材料介质无压渗流问题,提出了一种基于颗粒离散元的离散颗粒渗流模型(discrete seepage element model,DSEM)。该模型将连续介质离散化为密集堆积的颗粒系统,赋予颗粒流体性质,并通过颗粒间压力差模拟渗流过程。DSEM模型能够自动计算自由面位置和水头分布,无须预设自由面位置。为了验证DSEM模型的有效性,首先,模拟了土坝渗流问题,模拟结果与室内模型试验结果一致。随后,模拟了双材料矩形坝和分层土体渗流问题,并与其他数值方法进行比较,证明了DSEM在多种材料问题中的有效性。最后,将DSEM应用于分区梯形坝的渗流问题,成功计算了不同渗透系数下的自由面位置。研究结果表明,DSEM模型适用于多材料介质的无压渗流问题,为工程渗流问题提供了一种新的有效计算方法。 展开更多
关键词 离散元 无压渗流 自由面 多层材料介质
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Peristaltic Blood Flow with Gold Nanoparticles on a Carreau Nanofluid through a Non-Darcian Porous Medium
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作者 N. T. Eldabe G. M. Moatimid +1 位作者 A. A. El-Shekhipy Naglaa F. Aballah 《Journal of Biomaterials and Nanobiotechnology》 2018年第4期290-306,共17页
The article investigates the influences of a variable thermal conductivity and wall slip on a peristaltic motion of Carreau nanofluid. The model is concerned with heat and mass transfer inside asymmetric channel. The ... The article investigates the influences of a variable thermal conductivity and wall slip on a peristaltic motion of Carreau nanofluid. The model is concerned with heat and mass transfer inside asymmetric channel. The blood is considered as the base Carreau non-Newtonian fluid and gold (Au) as nanoparticles stressed upon. The Fronchiener effect of the non-Darcian medium is taken in consideration. The system is stressed upon a strong magnetic field and the Hall currents are completed. The problem is modulated mathematically by a system of non-linear partial differential equations which describe the fluid velocity, temperature and concentration. The system is reformulated under the approximation of long wavelength and low Reynolds number. It is solved on using multi-step differential transform method (Ms-DTM) as a semi-analytical method. A gold nanoparticle has increased the temperature distribution which is of great importance in destroying the cancer cells. 展开更多
关键词 Gold Nanoparticles Peristaltic Blood Flow Carreau NANOFLUID NON-DARCY Porous medium Variable Thermal Conductivity multi-STEP Differential Transform Method
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计及库容租赁与电量损益的混合式抽水蓄能电站容量电价计算 被引量:1
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作者 郭爱军 畅建霞 +3 位作者 王义民 谢正义 杨琪 王学斌 《水利学报》 北大核心 2025年第2期193-204,共12页
容量电价是体现抽水蓄能电站“弥补成本、合理收益”原则的重要方式,现有核定办法主要面向纯抽水蓄能电站,难以应用于具备特有成本、收益组成的混合式抽水蓄能电站。本文首先厘清混合式抽水蓄能电站典型的成本与收益组成,包括库容租赁... 容量电价是体现抽水蓄能电站“弥补成本、合理收益”原则的重要方式,现有核定办法主要面向纯抽水蓄能电站,难以应用于具备特有成本、收益组成的混合式抽水蓄能电站。本文首先厘清混合式抽水蓄能电站典型的成本与收益组成,包括库容租赁、增发季节性弃水电量以及抽发运行导致上下库电站电量损益等;其次,构建含混合式抽水蓄能电站的梯级水电站短期—中长期多尺度协同调峰模型,联合混合整数线性规划方法与粒子群优化算法求解;最后,与经营期定价模型耦合,提出计及库容租赁与电量损益的电站容量电价计算模型,为抽蓄电站经济性评估提供支撑。以西北某混合式抽水蓄能电站为例,结果表明:混合式抽水蓄能电站年均增发季节性弃水电量2.452亿kWh、年均库容租赁量约1063万m^(3),上游水电站年均发电量增加0.019亿kWh,下游水电站年均发电量减小0.057亿kWh。不考虑库容租赁与电量损益时,电站容量电价730元(kW·a);考虑二者时,按水电电价0.30元(kWh)、库容租赁单价0.5元m^(3)方案计算,容量电价为633元(kW·a),降幅近100元(kW·a),电站增发季节性弃水电量是降低容量电价的主要因素,库容租赁费用抬高了容量电价。研究完善了抽水蓄能电站容量电价计算体系,可为混合式抽水蓄能电站规划设计提供支撑。 展开更多
关键词 混合式抽水蓄能电站 容量电价 短期-中长期多尺度协同调峰 库容租赁 电量损益
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