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二极管箝位型逆变器 1

低调制度 1

冗余状态 1

古龙页岩 1

古龙页岩油 1

微纳米孔隙 1

载波PWM 1

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Synthesis of micro/meso porous carbon for ultrahigh hydrogen adsorption using cross-linked polyaspartic acid

Jun Wei, Jianbo Zhao, Di Cai, Wenqiang Ren, Hui Cao, Tianwei Tan

《化学科学与工程前沿（英文）》 2020年第14卷第5期页码 857-867 doi: 10.1007/s11705-019-1880-6

摘要： In addition to the specific surface area, surface topography and characteristics such as the pore size, pore size distribution, and micro/mesopores ratio are factors that determine the performance of porous carbons (PCs) in the fields of energy, catalysis, and adsorption. Based on the mechanism of weight loss of polyaspartic acid at high temperatures, this study provided a new method for adjusting the surface morphology of PCs by changing the cross-linking ratio of the precursor, where cross-linked polyaspartic acid was used as precursor without additional activating agents. N adsorption analysis indicated that the specific surface area of the obtained PCs was as high as 1458 m ·g , of which 1200 m ·g was the contribution of the microporous area and the highest pore volume was 1.13 cm ·g , of which the micropore volume was 0.636 cm ·g . The thermogravimetric analysis results of the precursor, and also the scanning electron microscopy and Brunauer–Emmet–Teller analysis results of the carbonization product confirmed that the prepared PCs presented multilevel pore structure, and the diameters of most pores were 0.78 and 3.97 nm; moreover, the pore size distribution was relatively uniform. This conferred the PCs the ultrahigh hydrogen adsorption capacity of up to 4.52 wt-% at 77 K and 1.13 bar, in addition to their great energy storage and catalytic potential.

关键词： porous carbon multilevel pores polyaspartic acid cross-linking hydrogen adsorption

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Perspectives in multilevel decision-making in the process industry

Braulio BRUNAUD, Ignacio E. GROSSMANN

《工程管理前沿（英文）》 2017年第4卷第3期页码 256-270 doi: 10.15302/J-FEM-2017049

摘要： Decisions in supply chains are hierarchically organized. Strategic decisions involve the long-term planning of the structure of the supply chain network. Tactical decisions are mid-term plans to allocate the production and distribution of materials, while operational decisions are related to the daily planning of the execution of manufacturing operations. These planning processes are conducted independently with minimal exchange of information between them. Achieving a better coordination between these processes allows companies to capture benefits that are currently out of their reach and improve the communication among their functional areas. We propose a network representation for the multilevel decision structure and analyze the components that are involved in finding integrated solutions that maximize the sum of the benefits of all nodes of the decision network. Although such task is very challenging, significant research progress has been made in each component of this structure. An overview of strategic models, mid-term planning models, and scheduling models is presented to address the solution of each node in the decision network. Coordination mechanisms for converging the integrated solutions are also analyzed, including solving large-scale models, multiobjective optimization, bi-level programming, and decomposition. We conclude by summarizing the challenges that hinder the full integration of multilevel decision making in supply chain management.

关键词： supply chain optimization enterprise-wide optimization multilevel optimization planning scheduling

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Development and advances in modular multilevel converter based HVDC projects in China

《工程管理前沿（英文）》页码 183-189 doi: 10.1007/s42524-022-0248-7

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关键词： high voltage direct current power converter power systems renewable energy ultra-high voltage

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探索知识体系的逻辑与架构：多层次、多尺度及介尺度复杂性

李静海

《工程（英文）》 2016年第2卷第3期页码 276-285 doi: 10.1016/J.ENG.2016.03.001

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Effect of TGO on the tensile failure behavior of thermal barrier coatings

Le WANG, Yuelan DI, Ying LIU, Haidou WANG, Haoxing YOU, Tao LIU

《机械工程前沿（英文）》 2019年第14卷第4期页码 452-460 doi: 10.1007/s11465-019-0541-2

摘要： Thermally grown oxide (TGO) may be generated in thermal barrier coatings (TBCs) after high-temperature oxidation. TGO increases the internal stress of the coatings, leading to the spalling of the coatings. Scanning electron microscopy and energy-dispersive spectroscopy were used to investigate the growth characteristics, microstructure, and composition of TGO after high-temperature oxidation for 0, 10, 30, and 50 h, and the results were systematically compared. Acoustic emission (AE) signals and the strain on the coating surface under static load were measured with AE technology and digital image correlation. Results showed that TGO gradually grew and thickened with the increase in oxidation time. The thickened TGO had preferential multi-cracks at the interface of TGO and the bond layer and delayed the strain on the surface of the coating under tensile load. TGO growth resulted in the generation of pores at the interface between the TGO and bond layer. The pores produced by TGO under tensile load delayed the generation of surface cracks and thus prolonged the failure time of TBCs.

关键词： thermally grown oxides thermal barrier coatings acoustic emission technology digital image correlation pores

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Porosity model for flows in CMP

ZHANG Chao-hui, YE Wei, LUO Jian-bin, WEN Shi-zhu

《机械工程前沿（英文）》 2006年第1卷第4期页码 418-423 doi: 10.1007/s11465-006-0050-y

摘要： In an effort to explore the contribution of the pad, which is usually full of pores, to the performance of CMP (chemical mechanical polishing), a three-dimensional flow model of CMP is presented by assuming that the fluids in the porous layer comply with Darcy s law, which states that the flow velocity is proportional to the pressure gradient and inverse proportional to the viscosity. The flow equation is deduced accordingly and, by taking advantage of the multilevel technique and line relaxation technique, numerical simulations are carried out to reveal the relationships between the load capacities and operational parameters (including pivot height, roll angle and pitch angle), under conditions with different porous parameters and different thicknesses of the porous layer. The little porous parameter will lead to a prominent increase of load capability (for instance, the load and the moment predicted), which is still augmented by the thicker layer parameter. This will result in a higher material removal ratio of CMP. A pad full of large pores will be used to deduce load capability, facilitating the free flow of the fluids through the pores. The research will add some insights on the mechanism of the CMP technique.

关键词： multilevel technique three-dimensional proportional research thicker

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Planning and analysis of the demonstration project of the MVDC distribution network in Zhuhai

Lu QU, Zhanqing YU, Qiang SONG, Zhichang YUAN, Biao ZHAO, Dawei YAO, Jianfu CHEN, Yao LIU, Rong ZENG

《能源前沿（英文）》 2019年第13卷第1期页码 120-130 doi: 10.1007/s11708-018-0599-2

摘要： The DC distribution system is an important development direction of the distribution system, which can improve the reliability and the quality of the power supply, and support the new energy, the energy storage, the electric vehicles, and the flexible access of AC and DC loads to grid. To realize the demonstration application of the DC distribution technology, China’s first demonstration project of the medium voltage DC distribution network will be built in Zhuhai, Guangdong Province to support the construction of the city energy internet. First, this paper analyzes the demand of the DC distribution network project, and puts forward the construction content and construction target. Then, it designs and analyzes the electrical connection mode, system operation mode, and startup and shutdown mode of the DC distribution network, and proposes the overall project construction plan. Finally, it conducts the specific project design and analysis, which mainly include the selection of equipment such as inverters, DC transformers and DC circuit breakers, the design and analysis of the DC control and protection system, the design and analysis of the over-voltage protection and the configuration scheme of the lightning arrester, and analysis of the system transient characteristics. The design and analysis of the engineering program is a combination of China’s distribution network engineering practice and technical characteristics, which lays a solid foundation for the advancement of the DC power distribution technology in China, and has reference value and demonstration effect for the design and construction of other projects.

关键词： MVDC distribution network DC solid state transformer DC circuit breaker modular multilevel converter

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低调制度下二极管箝位型多电平逆变器新型PWM控制方法

辛想,张庆范,胡顺全,李瑞来

《中国工程科学》 2007年第9卷第10期页码 91-96

摘要：

二极管箝位型多电平逆变器作为一种应用于高压大功率变换场合的变换器，其PWM控制技术是研究的核心内容之一。本文针对已有载波PWM方法中低调制度下电平退化的问题，提出了一种新颖的载波PWM方法，既便是在低调制度下，所有的电平都能够得到应用。仿真结果表明，这种方法可以提高二极管箝位型逆变器在低调制度下的器件利用率，使得逆变器在低调制度下工作于较高频率。

关键词：二极管箝位型逆变器载波PWM 低调制度冗余状态

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The effect of hierarchical single-crystal ZSM-5 zeolites with different Si/Al ratios on its pore structure and catalytic performance

Yuexin Hou, Xiaoyun Li, Minghui Sun, Chaofan Li, Syed ul Hasnain Bakhtiar, Kunhao Lei, Shen Yu, Zhao Wang, Zhiyi Hu, Lihua Chen, Bao-Lian Su

《化学科学与工程前沿（英文）》 2021年第15卷第2期页码 269-278 doi: 10.1007/s11705-020-1948-3

摘要： Hierarchical single-crystal ZSM-5 zeolites with different Si/Al ratios (Hier-ZSM-5- , where = 50, 100, 150 and 200) were synthesized using an ordered mesoporous carbon-silica composite as hard template. Hier-ZSM-5- exhibits improved mass transport properties, excellent mechanical and hydrothermal stability, and higher catalytic activity than commercial bulk zeolites in the benzyl alcohol self-etherification reaction. Results show that a decrease in the Si/Al ratio in hierarchical single-crystal ZSM-5 zeolites leads to a significant increase in the acidity and the density of micropores, which increases the final catalytic conversion. The effect of porous hierarchy on the diffusion of active sites and the final catalytic activity was also studied by comparing the catalytic conversion after selectively designed poisoned acid sites. These poisoned Hier-ZSM-5- shows much higher catalytic conversion than the poisoned commercial ZSM-5 zeolite, which indicates that the numerous intracrystalline mesopores significantly reduce the diffusion path of the reactant, leading to the faster diffusion inside the zeolite to contact with the acid sites in the micropores predominating in ZSM-5 zeolites. This study can be extended to develop a series of hierarchical single-crystal zeolites with expected catalytic performance.

关键词： hierarchical zeolites single crystalline interconnected pores improved diffusion performance benzyl alcohol self-etherification reaction

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古龙页岩油——揭示陆相页岩从生油到产油的另一个地学新领域 Article

何文渊, 朱如凯, 崔宝文, 张水昌, 蒙启安, 白斌, 冯子辉, 雷征东, 吴松涛, 何坤, 刘合, 孙龙德

《工程（英文）》 2023年第28卷第9期页码 79-92 doi: 10.1016/j.eng.2022.08.018

摘要：

大庆古龙页岩黏土矿物含量高达35%～45%，其粒径<0.0039 mm，石油流体横向流动性差，纵向基本不流动，因此古龙页岩一直被认为没有经济价值。近年来，我们从地球科学、渗流力学、热力学以及表面力学等多学科交叉研究入手，论证了古龙页岩油具高成熟度和高滞留烃的特点，高成熟阶段页岩排烃效率为32%～48%；有机质与黏土矿物复合体发育的孔隙与页理缝连通构成缝-孔组合储集体，是古龙页岩有利的储集空间；页岩油主要赋存在微纳米级别孔隙、层理缝与页理缝中，气油比高，可动流体饱和度中到高分布；页岩具高硬度、高弹性模量以及高断裂韧性特征，获得了古龙页岩勘探开发从生烃与储集理论创新到可动性、可压性、可采性等技术突破，实现了古龙页岩从生油到产油的重大转变，这对中国石油工业具有极其重要的科学价值和应用前景。

关键词：古龙页岩古龙页岩油微纳米孔隙页理缝陆相产油