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CO2 methanation and co-methanation of CO and CO2 over Mn-promoted Ni/Al2O3 catalysts

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Frontiers of Chemical Science and Engineering 2016年第2期10卷 273-280页

作者： Kechao Zhao zhenhua li li Bian Key Laboratory for Green Chemical Technology of Ministry of Education Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) School of Chemical Engineering and Technology Tianjin University Tianjin 300072 China College of Science Hebei University of Engineering Handan 056038 China

A series of Mn-promoted 15 wt-% Ni/Al2O3 catalysts were prepared by an incipient wetness impreg- nation method. The effect of the Mn content on the activity of the Ni/Al2O3 catalysts for CO2 methanation and the co- methanation of CO and CO2 in a fixed-bed reactor was investigated. The catalysts were characterized by N2 physisorption, hydrogen temperature-programmed reduc- tion and desorption, carbon dioxide temperature-pro- grammed desorption, X-ray diffraction and high- resolution transmission electron microscopy. The presence of Mn increased the number of CO2 adsorption sites and inhibited Ni particle agglomeration due to improved Ni dispersion and weakened interactions between the nickel species and the support. The Mn-promoted 15 wt-% Ni/ Al2O3 catalysts had improved CO2 methanation activity especially at low temperatures （250 to 400 ℃）. The Mn content was varied from 0.86% to 2.54% and the best CO2 conversion was achieved with the 1.71Mn-Ni/Al2O3 catalyst. The co-methanation tests on the 1.71Mn-Ni/ Al2O3 catalyst indicated that adding Mn markedly enhanced the CO2 methanation activity especially at low temperatures but it had little influence on the CO methanation performance. CO2 methanation was more sensitive to the reaction temperature and the space velocity than the CO methanation in the co-methanation process.

关键词： Mn promotion nickel catalysts C02 metha-nation co-methanation of CO and CO2

Deformation temperature and postdeformation annealing effects on severely deformed TiNi alloy by equal channel angular extrusion

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Journal of University of Science and Technology Beijing 2007年第6期14卷 533-537页

作者： zhenhua li Xianhua Cheng School of Mechanical and Power Engineering Shanghai Jiaotong University Shanghai 200030 China

Micron TiNi alloy blocks were fabricated at high temperature by equal channel angular extrusion （ECAE） using hotforged Ti-50.3at%Ni alloy as the raw material and the effects of deformation temperature and postdeformation annealing on the severely deformed TiNi alloy by ECAE were investigated. The results show that the TiNi alloy processed by ECAE undergoes severe plastic deformation, and lowering the deformation temperature and increasing the number of extrusions contribute to grain refinement. When the annealing temperature is below 873 K, static recovery is the main restoration process; when the temperature rises to 973 K, static recrystallization occurs. It is found that fine particles are precipitated when the TiNi alloy processed by ECAE is annealed at 773 K.

关键词： TiNi shape memory alloy equal channel angular extrusion (ECAE) static recrystallization ultrafine-grained (UFG) structure

Towards a Full-Stack Dev Ops Environment (Platform-as-a-Service) for Cloud-Hosted Applications

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Tsinghua Science and Technology 2017年第1期22卷 1-9页

作者： zhenhua li Yun Zhang Yunhao liu School of Software Tsinghua University Beijing 100084 China

If every programmer of cloud-hosted apps possessed exceptional technical capability and endless patience, the Dev Ops environment（also known as Platform-as-a-Service, or Paa S） would perhaps become irrelevant. However, the reality is almost always the opposite case. Hence, IT engineers dream of a reliable and usable Dev Ops environment that can substantially facilitate their developments and simplify their *** Dev Ops environments include Google App Engine, Docker, Kubernetes, Mesos, and so forth. In other words, Paa S bridges the gap between vivid IT engineers and stiff cloud systems. In this paper, we comprehensively examine state-of-the-art Paa S solutions across various tiers of the cloud-computing Dev Ops stack. On this basis,we identify areas of consensus and diversity in their philosophies and methodologies. In addition, we explore cutting-edge solutions towards realizing a more fine-grained, full-stack Dev Ops environment. From this paper,readers are expected to quickly grasp the essence, current status, and future prospects of Paa S.

关键词： cloud computing Platform-as-a-Service(PaaS) DevOps development operation environment

Conversion of natural gas to C_2 hydrocarbons via cold plasma technology

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Journal of Natural Gas Chemistry 2010年第4期19卷 375-379页

作者： Jing Lu zhenhua li Key Laboratory for Green Chemical Technology of Ministry of Education School of Chemical Engineering and Technology Tianjin University Tianjin 300072 China

The plasma technology served as a tool in unconventional catalysis has been used in natural gas conversion,because the traditional catalytic methane oxidative coupling reaction must be performed at high temperature on account of the stability of methane *** focus of this research is to develop a process of converting methane to C2 hydrocarbons with non-equilibrium plasma technology at room temperature and atmospheric *** was found that methane conversion increased and the selectivity of C2 hydrocarbons decreased with the *** optimum input voltage range was 40-80 V corresponding to high yield of C2 *** conversion decreased and the selectivity of C2 hydrocarbons increased with the inlet flow rate of *** proper methane flow rate was 20-40 ml/min （corresponding residence time 10-20 s）.The experimental results show that methane conversion was 47% and the selectivity of C2 hydrocarbons was 40% under the proper condition using atmospheric DBD cold plasma *** was found that the breakdown voltage of methane VB was determined by the type of electrode and the discharge gap width in this glow discharge *** breakdown voltage of methane VB,min derived from the Paschen law equation was established.

关键词： methane C2 hydrocarbons plasma

Coarse-Grained Cloud Synchronization Mechanism Design May Lead to Severe Traffic Overuse

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Tsinghua Science and Technology 2013年第3期18卷 286-297页

作者： zhenhua li Zhi-li Zhang Yafei Dai the Department of Computer Science and Technology Peking University the Department of Computer Science and Engineering University of Minnesota-Twin Cities

In recent years, cloud sync（hronization） services such as GoogleDrive and Dropbox have provided Internet users with convenient and reliable data storing/sharing functionality. The cloud synchronization mechanism （in particular, how to deliver the user-side data updates to the cloud） plays a critical role in cloud sync services because it greatly affects the cloud operation cost （in terms of sync traffic） and user experience （in terms of sync delay）. By comprehensively measuring tens of popular cloud sync services, we find that their cloud sync mechanisms differ greatly in sync performance and design granularity. Quite surprisingly, some very popular services （like GoogleDrive and 115 SyncDisk） utilize a quite coarse-grained cloud sync mechanism that may lead to severe traffic overuse. For example, updating 1-MB data may sometimes result in 260-MB sync traffic. In this paper, we conduct a comparative study of various cloud sync mechanisms by analyzing their respective pros and cons under different situations, unravel the pathological processes for their traffic overuse problems, and finally provide insights/solutions for better choosing/designing a cloud sync service.

关键词： cloud storage data synchronization operation cost user experience design granularity

Experimental study on the flow behaviour of water-sand mixtures in fractured rock specimens

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International Journal of Mining Science and Technology 2021年第3期31卷 377-385页

作者： Boyang Zhang Qingyuan He Zhibin lin zhenhua li School of Civil Engineering Henan Polytechnic UniversityJiaozuo 454000China State Key Laboratory of Coal Resources and Safe Mining School of MinesChina University of Mining and TechnologyXuzhou 221116China School of Minerals and Energy Resources Engineering UNSW SydneySydneyNSW 2052Australia

The study of flow behaviour of water-sand mixtures in fractured rocks is of great necessity to understand the producing mechanism and prevention of water inrush and sand gushing accidents.A self-developed seepage test system is used in this paper to conduct laboratory experiments in order to study the influence of the particle size distribution,the void ratio,and the initial mass of Aeolian sand on the flow *** is concluded that the water flow velocity is insensitive to the initial mass of the Aeolian sand but increases with the power exponent in the Talbot formula and the specimen *** outflow of the Aeolian sand increases with the power exponent in the Talbot formula,the specimen height,and the initial mass of the Aeolian ***,the outflow of the Aeolian sand changes exponentially with the water flow ***,it is found that the fractured specimen has a maximum sand filtration capacity beyond which the outflow of the Aeolian sand significantly increases with the initial mass of the Aeolian sand.

关键词： Water inrush and sand gushing accidents Seepage flow of water-sand mixtures Fractured specimens Sand filtration capacity

An efficient and globally optimal solution to perspective-n-line problem

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Chinese Journal of Aeronautics 2022年第3期35卷 400-407页

作者： Qida YU Guili XU Zhengsheng WANG zhenhua li College of Automation Engineering Nanjing University of Aeronautics and AstronauticsNanjing 211106China

This research develops an accurate and efficient method for the Perspective-n-line(Pn L)problem. The developed method addresses and solves Pn L via exploiting the problem’s geometry in a non-linear least squares fashion. Specifically, by representing the rotation matrix with a novel quaternion parameterization, the Pn L problem is first decomposed into four independent subproblems. Then, each subproblem is reformulated as an unconstrained minimization problem, in which the Kronecker product is adopted to write the cost function in a more compact form. Finally, the Groobner basis technique is used to solve the polynomial system derived from the first-order optimality conditions of the cost function. Moreover, a novel strategy is presented to improve the efficiency of the algorithm. It is improved by exploiting structure information embedded in the rotation parameterization to accelerate the computing of coefficient matrix of a cost function. Experiments on synthetic data and real images show that the developed method is comparable to or better than state-of-the-art methods in accuracy, but with reduced computational requirements.

关键词： Camera pose estimation Grobner basis Machine vision Perspective-n-line(PnL)problem Quaternion parameterization

Synthesis and Application of Carbon Nanotubes

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Journal of Natural Gas Chemistry 2006年第3期15卷 235-246页

作者： Qun Zeng zhenhua li Yuhong Zhou Key Laboratory for Green Chemical Technology School of Chemical Engineering and Technology Tianjin University Tianjin 300072 China

Owing to the unique structure, the superior physical and chemical properties, the super strong mechanical performances, and so on, carbon nanotubes have attracted the attention of researchers all over the world. In this article, the basic properties and the main production processes of carbon nanotubes are introduced in brief, and the progress of applied research for carbon nanotubes is reviewed.

关键词： carbon nanotube arc discharge chemical vapor deposition laser ablation application

Heralded entanglement between error-protected logical qubits for fault-tolerant distributed quantum computing

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Science China(Physics,Mechanics & Astronomy) 2024年第2期67卷 25-33页

作者： Jialun li Zhihao Xie Yachen li Yansen liang zhenhua li Tao li MIIT Key Laboratory of Semiconductor Microstructure and Quantum Sensing School of PhysicsNanjing University of Science and TechnologyNanjing 210094China National Laboratory of Solid State Microstructures Nanjing UniversityNanjing 210093China

Quantum error correction is essential for achieving reliable quantum information processing tasks,as it can mitigate the detrimental effects of noise by encoding single-qubit information into a larger quantum ***,the generation of distributed entanglement between logical qubits located within two spatially separated nodes presents a significant resource-intensive challenge that has yet to be *** we present a heralded protocol for generating distributed entanglement between two nonlocal error-protected logical qubits.A high-dimensional single photon can evolve physical qubits into a logical qubit that entangles with the photon and then converts logical qubit-photon entanglement into entanglement between two logical qubits,when the photon state is properly tuned and an effective photon-spin interface between single photons and individual spins is ***,the success of the entanglement generation is heralded by the detection of the photon,and the corresponding efficiency can,in principle,approach *** distinguished features make our protocol highly appealing for future large-scale quantum technologies.

关键词： quantum networks distributed entanglement error-protected logical qubits high-dimensional photons

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