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Effects of zinc on χ-Fe_(5)C_(2) for carbon dioxide hydrogenation to olefins:Insights from experimental and density function theory calculations

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Chinese Journal of Chemical Engineering 2023年第2期54卷 206-214页

作者： Xianglin Liu Minjie Xu chenxi cao Zixu Yang Jing Xu State Key Laboratory of Chemical Engineering East China University of Science and TechnologyShanghai 200237China Maoming Branch R&D Institute SINOPECMaoming 525000China Key Laboratory of Smart Manufacturing in Energy Chemical Process Ministry of EducationEast China University of Science and TechnologyShanghai 200237China

Production of light olefins from CO_(2), the primary greenhouse gases, is of great importance to mitigate the adverse effects of CO_(2) emission on environment and to supply the value-added products from nonpetroleum resource. However, development of robust catalyst with controllable selectivity and stability remains a challenge. Herein, we report that Zn-promoted Fe catalyst can boost the stable and selective production of light olefins from CO_(2). Specifically, the Zn-promoted Fe exhibits a highly stable activity and olefin selectivity over 200 h time-on-stream compared to the unpromoted Fe catalyst, primarily owing to the preservation of active χ-Fe_(5)C_(2) phase. Structural characterizations of the spent catalysts suggest that Zn substantially regulates the content of iron carbide on the surface and suppresses the reoxidation of bulk iron carbide during the reaction. DFT calculations confirm that adsorption of surface carbon atoms and graphene-like carbonaceous species are not thermochemically favored on Zn-promoted Fe catalyst. Carbon deposition by CAC coupling reactions of two surface carbon atoms and dehydrogenation of CH intermediate are also inhibited. Furthermore, the effects of Zn on antioxidation of iron carbide were also investigated. Zn favored the hydrogenation of surface adsorbed oxygen atoms to H_(2)O and the desorption of H_(2)O, which reduces the possibility of surface carbide being oxidized by the chemisorbed oxygen.

关键词： Reaction engineering χ-Fe_(5)C_(2) Zn promoter Carbon dioxide Hydrogenation Density function theory

Optimization of sensor deployment sequences for hazardous gas leakage monitoring and source term estimation

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Chinese Journal of Chemical Engineering 2023年第4期56卷 169-179页

作者： Jikai Dong Bing Wang Xinjie Wang chenxi cao Shikuan Chen Wenli Du Key Laboratory of Smart Manufacturing in Energy Chemical Process Ministry of EducationEast China University of Science and TechnologyShanghai 200237China

Nowadays, chemical safety has attracted considerable attention, and chemical gas leakage monitoring and source term estimation(STE) have become hot spots. However, few studies have focused on sensor layouts in scenarios with multiple potential leakage sources and wind conditions, and studies on the risk information(RI) detection and prioritization order of sensors have not been performed. In this work, the monitoring area of a chemical factory is divided into multiple rectangles with a uniform mesh. The RI value of each grid node is calculated on the basis of the occurrence probability and normalized concentrations of each leakage scenario. A high RI value indicates that a sensor at a grid node has a high chance of detecting gas concentrations in different leakage scenarios. This situation is beneficial for leakage monitoring and STE. The methods of similarity redundancy detection and the maximization of sensor RI detection are applied to determine the sequence of sensor locations. This study reveals that the RI detection of the optimal sensor layout with eight sensors exceeds that of the typical layout with 12 sensors. In addition, STE with the optimized placement sequence of the sensor layout is numerically simulated. The statistical results of each scenario with various numbers of sensors reveal that STE is affected by sensor number and scenarios(leakage locations and winds). In most scenarios, appropriate STE results can be retained under the optimal sensor layout even with four sensors. Eight or more sensors are advised to improve the performance of STE in all scenarios. Moreover, the reliability of the STE results in each scenario can be known in advance with a specific number of sensors. Such information thus provides a reference for emergency rescue.

关键词： Gas leakage Source term estimation Sensor layout Risk information Numerical simulation Optimization

A case study of comparing two dimerized acceptor molecules built by different branch-connected and terminal-connected approaches

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Science China Chemistry 2024年第5期67卷 1687-1696页

作者： Kangqiao Ma Huazhe Liang Yuxin Wang Tengfei He Tainan Duan Xiaodong Si Wendi Shi Guankui Long Xiangjian cao Zhaoyang Yao Xiangjian Wan chenxi Li Bin Kan Yongsheng Chen State Key Laboratory and Institute of Elemento-Organic Chemistry Frontiers Science Center for New Organic MatterThe Centre of Nanoscale Science and Technology and Key Laboratory of Functional Polymer MaterialsInstitute of Polymer ChemistryRenewable Energy Conversion and Storage Center(RECAST)College of ChemistryNankai UniversityTianjin 300071China School of Materials Science and Engineering National Institute for Advanced MaterialsRenewable Energy Conversion and Storage Center(RECAST)Nankai UniversityTianjin 300350China Chongqing Institute of Green and Intelligent Technology Chongqing SchoolUniversity of Chinese Academy of Sciences(UCAS Chongqing)Chinese Academy of SciencesChongqing 400015China

Dimerized small-molecule acceptors(SMAs) built by the conventional connection of terminal groups of monomers have contributed to exciting long-term stabilities of organic solar cells(OSCs). However, device efficiencies, especially fill factors(FFs), still need to be improved. This probably originates from unsymmetrical molecular structure/conformation-determined less compact/ordered molecular stackings, such as ineffective stackings of constraint terminals. Herein, an exotic dimerized SMA of BC-Th is established by bridging the branched groups(BC-type, branch coupling) of two monomers rather than conventional terminal units(TC-type, terminal coupling). Benefiting from the three-dimensional conformation and more uncurbed terminals,BC-Th exhibits multiple molecular orientations along with a larger dielectric constant and electron mobility compared with TCTh. Finally, an efficiency of 17.43% is achieved by BC-Th-based OSCs, along with the highest FF of 79.13% among all dimerized SMAs-based OSCs to date. When introducing L8-BO as the third component, overall enhanced efficiency of 18.05%and FF of 80.11% are further afforded. Contrarily, TC-Th-based OSCs exhibit much inferior PCE of 16.29% and FF of 74.81%,demonstrating the great advantages of “branch coupling” over “terminal coupling” when building dimerized SMAs.

关键词： organic solar cells dimerized acceptor molecules branch coupling morphology control stability

高海拔环境下大容量直流空气断路器灭弧性能研究

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电工技术学报 2024年第3期39卷 863-874页

作者：李静易晨曦彭世东曹云东于龙滨沈阳工业大学特种电机与高压电器重点实验室沈阳110870 辽宁省电力有限公司电力科学研究院沈阳110006

高原轨道交通和电工产业转型对起关键保护作用的大容量直流空气断路器(LC-DCCB)提出了更高要求,但现有产品在高海拔地区的开断仍存在一定问题。该文以轨道交通用LC-DCCB为研究对象,首先基于磁流体动力学(MHD)理论,考虑湍流效应的影响,... 详细信息

高原轨道交通和电工产业转型对起关键保护作用的大容量直流空气断路器(LC-DCCB)提出了更高要求,但现有产品在高海拔地区的开断仍存在一定问题。该文以轨道交通用LC-DCCB为研究对象,首先基于磁流体动力学(MHD)理论,考虑湍流效应的影响,对其在高海拔环境下开断18 kA短路电流进行仿真;然后对电弧形态及灭弧室内温度场、电磁场、气流场进行分析,得出高海拔地区空气电弧开断困难的主要原因;最后根据仿真与理论分析,考虑采用合理数量和布局的间插式U型栅片改善电弧开断特性。结果表明:随着海拔的升高,电弧前期运动速度加快,但断路器的灭弧性能降低;在高海拔环境下电弧存在严重的弧根粘滞和弧根拖尾现象,弧根拖尾畸变空间电场,不利于熄弧;同时,在不同海拔环境下,电弧会产生不同程度的反向运动现象,易导致弧后重燃。该研究深入揭示了高海拔环境下LC-DCCB电弧演变过程及复杂开断现象背后的物理本质,可为该类产品研发提供理论指导。

关键词：高海拔大容量直流空气断路器弧根拖尾电弧反向弧后重燃

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基于点云与NeRF的三维重建系统

软件 2024年第4期45卷 11-14页

作者：曹晨曦任泰安合肥工业大学计算机与信息学院安徽合肥230601 合肥工业大学本科生院工程素质教育中心安徽合肥230601

三维重建可以帮助人们更好地查看被重建对象的细节,广泛应用于物体展示、虚拟场景模拟、文物保护等场景中。传统的多视图三维重建容易出现大量噪声、空洞等问题,而且展示效果不佳。新兴的利用神经网络进行三维重建的NeRF算法虽然能够达... 详细信息

三维重建可以帮助人们更好地查看被重建对象的细节,广泛应用于物体展示、虚拟场景模拟、文物保护等场景中。传统的多视图三维重建容易出现大量噪声、空洞等问题,而且展示效果不佳。新兴的利用神经网络进行三维重建的NeRF算法虽然能够达到接近真实的效果,但是渲染的速度慢,无法满足交互的要求。文章通过结合两种方法,得到了一种兼顾交互效果与渲染效果的三维重建系统。结果表明,本文系统在采集的稀疏图片数据集上,达到了较好的交互与渲染效果。

关键词：三维重建 NeRF 点云 Web技术

Blockchain-based fog radio access networks:Architecture,key technologies,and challenges

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Digital Communications and Networks 2022年第5期8卷 720-726页

作者： Zixin Wang Bin cao chenxi Liu Congfang Xu Lei Zhang State Key Laboratory of Networking and Switching Technology Beijing University of Posts and TelecommunicationsBeijing100876China China Electrics Technology Cyber Security Co.Ldt ChengduSichuan610041China James Watt School of Engineering University of GlasgowGlasgowG128QQUK

Fog Radio Access Network(F-RAN)has been regarded as a promising solution to the alleviation of the ever-increasing traffic burden on current and future wireless networks,for it shifts the caching and computing resources from remote cloud to the network edge.However,it makes wireless networks more vulnerable to security attacks as well.To resolve this issue,in this article,we propose a secure yet trustless Blockchain-based F-RAN(BF-RAN),which allows a massive number of trustless devices to form a large-scale trusted cooperative network by leveraging the key features of blockchain,such as decentralization,tamper-proof,and traceability.The architecture of BF-RAN is first presented.Then,the key technologies,including access control,dynamic resource management,and network deployment are discussed.Finally,challenges and open problems in the BF-RAN are identified.

关键词： F-RAN Blockchain 5G Internet of things

磷石膏基胶凝材料和骨料制备C40高性能混凝土研究

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混凝土 2024年第2期 162-167,172页

作者：马雪婷丁庆军黄绍龙李进辉刘晨曦金帆曹杰荣曹玉贵武汉理工大学三亚科教创新园湖北武汉430000 武汉理工大学材料科学与工程学院湖北武汉430000 武汉纺织大学湖北武汉430000 湖北大学湖北武汉430000

磷石膏基胶凝材料和骨料制备混凝土,可为高消纳磷石膏固废提供新思路;然而将磷石膏同时作胶凝材料和骨料制备混凝土的研究鲜有报道。为此研究了磷石膏基胶凝材料组成、骨料级配、砂率和水胶比对混凝土性能的影响规律,并通过XRD和SEM微... 详细信息

磷石膏基胶凝材料和骨料制备混凝土,可为高消纳磷石膏固废提供新思路;然而将磷石膏同时作胶凝材料和骨料制备混凝土的研究鲜有报道。为此研究了磷石膏基胶凝材料组成、骨料级配、砂率和水胶比对混凝土性能的影响规律,并通过XRD和SEM微观测试初探其机理。结果表明:采用5%的P·O 42.5级水泥、30%的磷石膏、65%矿粉制成的胶凝材料时,外掺0.5%NaOH+5%水玻璃和1%NaAlO_(2)复合激发剂,控制胶凝材料用量600 kg/m^(3),磷石膏破碎砂替代40%河砂,砂率41%,水胶比0.34,可制备出工作性能良好,初凝时间大于25 h,3 d、28 d及60 d抗压强度分别大于20.0 MPa、48.0 MPa和55.0 MPa,绝热温升低于35℃,60 d膨胀率大于180με的大掺量磷石膏基C40低温升微膨胀高性能混凝土。混凝土胶凝材料主要水化产物为AFt和C-S-H凝胶,胶凝浆体可穿透磷石膏骨料表面空隙,产生机械嵌锁作用使磷石膏骨料与胶凝浆基体结合更加紧密。

关键词：磷石膏胶凝材料骨料混凝土性能

A Low Reorganization Energy and Two-dimensional Acceptor with Four End Units for Organic Solar Cells with Low E_(loss)

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Chinese Journal of Polymer Science 2022年第8期40卷 921-927,I0008页

作者： Hongbin Chen Xiangjian cao Xiaoyun Xu chenxi Li Xiangjian Wan Zhaoyang Yao Yongsheng Chen State Key Laboratory and Institute of Elemento-Organic Chemistry The Centre of Nanoscale Science and Technology and Key Laboratory of Functional Polymer MaterialsRenewable Energy Conversion and Storage Center(RECAST)College of ChemistryNankai UniversityTianjin300071China State Key Laboratory for Modification of Chemical Fibers and Polymer Materials Center for Advanced Low-dimension MaterialsCollege of Materials Science and EngineeringDonghua UniversityShanghai201620China

A novel two-dimensional A-D-A acceptor named as CH8 with four electron-withdrawing end units has been successfully designed and synthesized.The enlarged conjugation in two directions renders CH8 exhibit an extremely low electron reorganization energy of 98 meV,which makes CH8 a potential candidate for outstanding organic semiconductor material.When blended with PM6,a considerate power conversion efficiency of 9.37%along with a high open-circuit voltage(V_(oc))0.889 V and low energy loss(E_(loss))below 0.6 eV is achieved.These results indicate that the two-dimensional A-D-A molecule with four electron-withdrawing end units is an effective molecular design strategy to achieve lower voltage loss and also possible high performance for organic photovoltaics if ideal morphology could be achieved.

关键词： Two-dimensional A-D-A acceptor Reorganization energy Energy loss(E_(loss)) Organic photovoltaics

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Silk Fibroin Nacre

Advanced Fiber Materials 2022年第5期4卷 1191-1208页

作者： chenxi Zhao Yawen Liu Zhuochen Lv Leitao cao Jing Ren Zhengzhong Shao Shengjie Ling School of Physical Science and Technology ShanghaiTech University393 Middle Huaxia RoadShanghai 201210China State Key Laboratory of Molecular Engineering of Polymers Department of Macromolecular ScienceLaboratory of Advanced MaterialsFudan UniversityShanghai 200433China

Producing lightweight,mechanically strong,ductile,and biocompatible materials remains a significant challenge in material engineering due to the conflict between structural and mechanical features.Inspired by the“brick-and-mortar”structure of nacre,a construction with a naturally optimized structure-performance-function relationship,this study developed silk fibroin(SF)nacre as a silk protein-based nacre by integrating ice-templating and thermoplastic molding techniques.SF nacres are similar to natural nacre in microstructure,and their strength and toughness are even superior to natural nacres.These mechani-cal properties permit machining by extreme processing techniques,such as ion beam lithography.Furthermore,SF nacre can be used to modulate the polarization of laser beams and generate bright structural colors.Biocompatibility,mechanical robustness,good processability,and tunable coloration allow SF nacres to be used as a plastic replacement for structural engineering and biomedical use,showing promising advancement of such implantable devices towards clinical translation.

关键词： Silk fibroin Nacre Mechanical properties Optical modulation