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Crystal Structure of 5-(l-Menthyloxy)-3-Bromo-4-(R)-(+)-Methylbenzylamino-2(5H)-Furanone

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Chinese Journal of Structural Chemistry 1999年第2期18卷 32-34页

作者： geng, z Huang, B Chen, QH Capital Normal Univ Dept Chem Beijing 100037 Peoples R China Beijing Normal Univ Dept Chem Beijing 100875 Peoples R China

The crystal structure of the title compound 1, C 22 H 30 BrNO 3, was determined by X ray analysis at 296(1)K. The crystal belongs to othorhombic system, space group P2 12 12 1 with a=9.842(5), b=12.510(5), c=17.763(6) , V=2187(3)  3, z=4, M r=436.37, D x =1.33 g/cm 3, μ =18.79 cm 1 , F(000) =912 and the final R=0.047 and R w=0.053 for 1429 observed reflections with I≥3σ(I). Structure analysis reveals that the absolute configuration at C 14 of the acetal carbon of the title compound is S.

关键词： crystal structure 2(5H) furanone absolute configuration.

Structure and Magnetic Properties of S-doped Mn_3O_4/S Composited Nanoparticles and Mn_3O_4 Nanoparticles

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Journal of Materials Science & Technology 2011年第6期27卷 503-506页

作者： X. He z.H. Wang D.Y. geng z.D. zhang Shenyang National Laboratory for Materials Science Institute of Metal Research and International Centre for Materials Physics Chinese Academy of Sciences Shenyang 110016 China

Composited nanoparticles,consisting of Mn3O4,S-doped Mn3O4 and S,were synthesized by co-precipitation reaction and Mn3O4 nanoparticles were then obtained after removing the pure S from the composited *** Mn3O4-type phase with larger lattice constant a was formed by doping *** fixed temperatures below Curie temperature（TC）,the magnetization of the S-doped Mn3O4/S composited nanoparticles was smaller than that of the Mn3O4 *** blocking temperature was 36.3 and 34.8 K for Sdoped Mn3O4/S composite and Mn3O4 nanoparticles,*** anisotropy field of S-doped Mn3O4/S composite was determined to be about 55.3 kOe.

关键词： Nanostructured materials Chemical synthesis X-ray diffraction Magnetic measurements

CONSTITUTIVE RELATIONSHIP OF IN718 ALLOY FOR THERMOVISCOPLASTIC AND MICROSTRUCTURE EVOLUTION COUPLED ANALYSIS

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Acta Metallurgica Sinica(English Letters) 2007年第5期20卷 373-379页

作者： D. Liu Y.H. Yang J. geng z.J. Luo School of Materials Science Northwestern Polytechnical University Xi＇an 710072 China

The interaction between thermomechanical parameters and microstructure evolution is so intense that it must be considered during the finite element method （FEM） simulation of the hot plastic working process, for materials that are difficult to deform. Taking the microstructure evolution into account, a novel type of constitutive relationship has been put forward for the IN718 alloy. The microstructure evolution model was first established for the dominant microstructure evolution processes. Then the microstructure evolution models and the method to determine the local flow stress of the corresponding microstructure for current thermomechanical parameters and deformation history were presented. Once the local flow stresses of different structures and their volume contributions were defined, the apparent flow stress of the material could be determined as the weighted sum of the local flow stresses and volume contributions. To validate the proposed method, a thermoviscoplastics and microstructure evolution coupled analysis for a forging process of a critical IN718 disk forging was performed. The predicting results were in close agreement with the experimental data.

关键词： constitutive relationship microstructure evolution numerical simulation IN718 alloy

Mixed Dead-time Effect Suppression Strategy for Modular Multilevel Converters

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CSEE Journal of Power and Energy Systems 2024年第3期10卷 1075-1084页

作者： zhi geng Minxiao Han School of Electrical and Electronic Engineering North China Electric Power UniversityBeijing 102206China IEEE

Dead time is necessary for the coupled power switches to prevent shoot-through,especially in the modular multilevel converters(MMCs)with a large number of power *** paper proposes a dead-time effect suppression strategy for MMCs with nearest level *** operational principles of MMCs are first *** to the operational features of MMCs,the method that removes a switching signal from the coupled switches and the reduced switching frequency voltage balancing algorithms(RSFVBAs)are mixed in the proposed *** the intervals that are furthest away from the zerocrossing points(zCP)of arm currents,the single switching signal method can completely eliminate the dead-time effect(DTE).Alternatively,the DTE is suppressed by the RSFVBA in intervals that are close to the *** the combination of the two methods,the dependence of the DTE suppression method on currents is reduced and the influences of zCP are also released without degrading the normal operation performance of ***,the output performance of MMCs is improved and the voltage stress on the arm inductor dramatically ***,the validation of the method is verified by the simulation results with the professional tool Matlab/Simulink.

关键词： Dead-time effect modular multilevel converters switching frequency voltage balancing algorithm

Investigation and measurement of old building response to the overlapped shield tunnel of multiple schemes in the sandy cobble stratum

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Underground Space 2024年第2期15卷 260-274页

作者： Xue Li Aopeng geng School of Geoscience and Technology Southwest Petroleum UniversityChengduSichuan 610500China China Railway Construction Bridge Engineering Bureau Group Co. Ltd.Tianjin 300300China

Ground movements due to tunneling are becoming increasingly critical as buildings are located around construction *** study proposes a new combined reinforcement method using a foundation grouting oblique pipe *** former improves the bearing capacity of the subsoil,and the latter blocks the transmission of soil deformation,which weakens the influence of construction during overlapped tunnel *** on this new method,a case study of the shield tunneling response to an old building in Line 6 of China’s Chengdu Metro is ***,three-dimensional numerical models without reinforcement,traditional foundation grouting reinforcement,and the new combined reinforcement schemes were *** numerical simulation performance was verified using a set of field instrumentation data,which demonstrated that the old building response to the overlapped tunnels was under control,and the maximum deformation,angular distortion,and principal tensile strain of the building were 5.25 mm,5.1010–6 rad/m,and 0.0081%,*** with the traditional reinforcement scheme,the deformation,angular distortion,and principal tensile strain in the combined reinforcement scheme were reduced by 54.78%,71.02%,and 70.22%,*** results have important implications for the design and construction of shield tunnels and their response to old buildings.

关键词： Overlapped tunnels Reinforcement schemes Under-crossing Old building Numerical simulation

Boosting electrocatalytic nitrate reduction to ammonia via Cu_(2)O/Cu(OH)_(2)heterostructures promoting electron transfer

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Nano Research 2024年第6期17卷 4898-4907页

作者： Jing geng Sihan Ji Anhui Province International Research Center on Advanced Building Materials School of Materials Science and Chemical EngineeringAnhui Jianzhu UniversityHefei 230601China Anhui Province Key Laboratory of Advanced Building Materials Anhui Jianzhu UniversityHefei 230601China School of Energy Materials and Chemical Engineering Hefei UniversityHefei 230601China

Electrocatalytic nitrate(NO_(3)^(−))reduction to ammonia(NH_(3))offers a viable approach for sustainable NH_(3)production and environmental ***(Cu)possesses a distinctive electronic structure,which can augment the reaction kinetics of NO_(3)^(−)and impede hydrogen evolution reaction(HER),rendering it a promising contender for the electrosynthesis of NH_(3)from NO_(3)^(−).Nevertheless,the role of Cu_(2)O in copper-based catalysts still requires further investigation for a more comprehensive ***,the Cu_(2)O/Cu(OH)_(2)heterostructures are successfully fabricated through liquid laser irradiation using CuO nanoparticles as a *** and theoretical researches reveal that Cu_(2)O/Cu(OH)_(2)heterostructure exhibits enhanced electrocatalytic performance for NO_(3)^(−)to NH_(3)because Cu(OH)_(2)promotes electron transfer and reduces the valence state of Cu active site in Cu_(2)***−0.6 V(*** hydrogen electrode(RHE)),the NH_(3)yield reaches its maximum at 1630.66±29.72μg·h^(−1)·mgcat^(−1),while the maximum of Faraday efficiency(FE)is 76.95%±5.51%.This study expands the technical scope of copper-based catalyst preparation and enhances the understanding of the electrocatalytic mechanism of NO_(3)^(−)to NH_(3).

关键词： Cu_(2)O/Cu(OH)_(2)heterostructures electron transfer ammonia synthesis electrocatalysts nitrate

Structural engineered living materials

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Nano Research 2024年第2期17卷 715-733页

作者： Yang geng zian Jia Ling Li 635 Prices Fork Road Department of Mechanical EngineeringVirginia Polytechnic Institute and State UniversityBlacksburg VA24061USA

Biological structural materials not only exhibit remarkable mechanical properties but also often embody dynamic characteristics such as environmental responsiveness,autonomy,and self-healing,which are difficult to achieve in conventional engineering *** merging materials science,synthetic biology,and other disciplines,engineered living materials(ELMs)provide a promising solution to combine living organisms with abiotic components,thus facilitating the construction of functional“living”*** natural materials,ELMs possess vitality and hold immense application potential in areas such as medicine,electronics,and construction,captivating increasing research attention *** an emerging branch of ELMs,structural ELMs aim to mimic living biological structural materials by achieving desired mechanical performance while maintaining important“living”*** we summarize the recent progress and provide our perspectives for this emerging research *** first summarize the superiority of structural ELMs by reviewing biological structural materials and biomimetic material design ***,we provide a systematic discussion on the definition and classifications of structural ELMs,their mechanical performance,and physiological ***,we summarize some critical challenges faced by structural ELMs and highlight directions of future *** hope this review article can provide a timely summary of the state of the art and relevant perspectives for future development of structural ELMs.

关键词： structural materials engineered living materials(ELMs) structural ELMs composites mechanical properties

Optimizing urban block morphologies for net-zero energy cities:Exploring photovoltaic potential and urban design prototype

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Building Simulation 2024年第4期17卷 607-624页

作者： Xiaotian geng Dong Xie zhonghua Gou School of Urban Design Wuhan UniversityWuhanChina

The morphology of urban areas plays a crucial role in determining solar potential,which directly affects photovoltaic capacity and the achievement of net-zero *** study focuses on the City of Melbourne to investigate the utilization of solar energy across different urban densities and proposes optimized *** analysis encompasses blocks with diverse population densities,examining medium and high-density *** utilizing a multi-objective genetic optimization approach,the urban morphology of these blocks is *** findings indicate that low-density blocks exhibit photovoltaic potential ranging from 1 to 6.6 times their total energy *** and high-density blocks achieve photovoltaic potential levels approximately equivalent to 40%-85%of their overall energy ***,significant variations in photovoltaic potential are observed among different urban forms within medium and high-density ***“elevated corners with central valley”prototype is proposed as an effective approach,enhancing the overall photovoltaic potential by approximately 14%.This study introduces novel analytical concepts,shedding light on the intricate relationship between urban morphologies and photovoltaic potential.

关键词： net-zero energy solar energy urban density urban morphology multi-objective optimization photovoltaic potential

Point defects in 2-D liquid crystals with a singular potential:Profiles and stability

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Science China Mathematics 2024年第11期67卷 2515-2540页

作者： zhiyuan geng Wei Wang Basque Center for Applied Mathematics School of Mathematical Sciences Zhejiang University

We study radial symmetric point defects with degree k/2 in the 2-D disk or R2in the Q-tensor framework with a singular bulk energy,which is defined by Bingham ***,we obtain the existence of solutions for the profiles of radial symmetric point defects with degree k/2 in the 2-D disk or ***,we prove that the solution is stable for |k| = 1 and unstable for |k| > *** identities are derived and utilized throughout the proof of existence and stability/instability.

关键词： radial symmetric point defects singular bulk potential Bingham closure stability