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Coupling p+n field-effect transistor circuits for low concentration methane gas detection

Sensors (Switzerland) 2018年第3期18卷 787-787页

作者： Zhou, Xinyuan Yang, Liping Bian, Yuzhi Ma, Xiang Han, Ning Chen, Yunfa State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences Beijing100190 China University of Chinese Academy of Sciences No. 19A Yuquan Road Beijing100049 China Center for Excellence in Regional Atmospheric Environment Institute of Urban Environment Chinese Academy of Sciences Xiamen361021 China

Nowadays, the detection of low concentration combustible methane gas has attracted great concern. In this paper, a coupling p+n field effect transistor (FET) amplification circuit is designed to detect methane gas. By optimizing the load resistance (RL), the response to methane of the commercial MP-4 sensor can be magnified ~15 times using this coupling circuit. At the same time, it decreases the limit of detection (LOD) from several hundred ppm to ~10 ppm methane, with the apparent response of 7.0 ± 0.2 and voltage signal of 1.1 ± 0.1 V. This is promising for the detection of trace concentrations of methane gas to avoid an accidental explosion because its lower explosion limit (LEL) is ~5%. The mechanism of this coupling circuit is that the n-type FET firstly generates an output voltage (VOUT) amplification process caused by the gate voltage-induced resistance change of the FET. Then, the p-type FET continues to amplify the signal based on the previous VOUT amplification process. © 2018 by the authors. Licensee MDPI, Basel, Switzerland.

关键词： Field effect transistors

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Regime-specific multi-objective variational principle of compromise in competition at mesoscales

arXiv

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arXiv 2017年

作者： Li, Jinghai Huang, Wenlai Chen, Jianhua Ge, Wei Hou, Chaofeng State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences Beijing100190 China

The energy-minimization multiscale (EMMS) principle of compromise in competition is believed to be generally applicable for all mesoscale problems at different levels in the real world, spanning from elementary particles to the universe. This stimulated a fundamental proposition of the concept of mesoscience. This article discusses a potential universality of the regime-specific multi-objective variational feature of this underlying principle through case studies in chemical engineering. It is also elucidated why the currently available variational principles are not applicable to the mesoscale problems. The paper concludes with prospects on future study. Copyright © 2017, The Authors. All rights reserved.

关键词： Variational techniques

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Condensation of Eigen microstate in statistical ensemble and phase transition

arXiv

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arXiv 2018年

作者： Hu, Gaoke Liu, Teng Liu, Maoxin Chen, Wei Chen, Xiaosong Institute of Theoretical Physics Key Laboratory of Theoretical Physics Chinese Academy of Sciences P.O. Box 2735 Beijing100190 China School of Systems Science Beijing Normal University Beijing100875 China School of Physical Sciences University of Chinese Academy of Science No. 19A Yuquan Road Beijing100049 China State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences Beijing100190 China State Key Laboratory of Information Photonics and Optical Communications & School of Science Beijing University of Posts and Telecommunications Beijing100876 China

In a statistical ensemble with M microstates, we introduce an M × M correlation matrix with the correlations between microstates as its elements. Using eigenvectors of the correlation matrix, we can define eigen microstates of the ensemble. The normalized eigenvalue by M represents the weight factor in the ensemble of the corresponding eigen microstate. In the limit M → ∞, weight factors go to zero in the ensemble without localization of microstate. The finite limit of weight factor when M → ∞ indicates a condensation of the corresponding eigen microstate. This indicates a phase transition with new phase characterized by the condensed eigen microstate. We propose a finite-size scaling relation of weight factors near critical point, which can be used to identify the phase transition and its universality class of general complex systems. The condensation of eigen microstate and the finite-size scaling relation of weight factors have been confirmed by the Monte Carlo data of one-dimensional and two-dimensional Ising models. Copyright © 2018, The Authors. All rights reserved.

关键词： Condensation

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Coupled neutronics/thermal-hydraulics and safety characteristics of liquid-fueled Molten Salt Reactors

Coupled neutronics/thermal-hydraulics and safety characteris...

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作者： Qiu, S. Zhang, D. Liu, L. Liu, M. Xu, R. Gong, C. Su, G.H. State Key Laboratory of Multiphase Flow in Power Engineering School of Nuclear Science and Technology Xi'an Jiaotong University Xi'an710049 China

Molten salt reactor (MSR) as one candidate of the Generation IV advanced nuclear power systems is attracted more attention in China due to its top ranked fuel cycle and thorium utilization. The MSRs are characterized by using liquid-fuel, which offers complicated coupling problem of neutronics and thermal hydraulics. In this paper, the fundamental model and numerical method are established to calculate and analyze the safety characteristics for liquid-fuel MSRs. The theories and methodologies are applied to the MOSART concept. The liquid-fuel flow effects on neutronics, reactivity coefficients and three operation parameters' influences at steady state are obtained, which provide the basic information for safety analysis. The unprotected loss of flow transient is calculated, the results of which shows the inherent safety characteristics of MOSART due to its strong negative reactivity feedbacks. © Carl Hanser Verlag, München.

关键词： Molten salt reactor

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Adsorption Characteristics of Sulfuric Acid Mist on Fly Ash in Low-low temperature Flue Gas System

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Energy Procedia 2017年 142卷 3307-3312页

作者： Yubo Zhang Yu Yan Jianhua Liu Qingwen Qi Lei Deng Defu Che Xi’an Thermal Power Research Institute Co. Ltd. Xi’an 710032 China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an 710049 China Ningxia Electric Power Research Institute Ningxia 750002 China

Low-low temperature flue gas system which also called MHI high efficiency system developed by Mitsubishi Corporation has gained comprehensive attention in Japan, European countries and American. However, the applications of this system in China are facing several sever problems about corrosion and ash fouling. This paper focuses on the adsorption characteristics of sulfuric acid mist on fly ash during the flue gas cooling process in the exchanger before the electrostatic precipitator. The experimental results indicate that there is an optimum adsorption temperature for the adsorption of sulfuric acid mist, and this temperature is about 30 ℃ lower than the acid dew point. The process of adsorption is mainly dominated by chemical reactions rather than physical reactions, and the alkali metals (Na, K) and alkaline earth metals (Mg, Ca) are the main factors which influence the chemical reaction rate, especially the Na element. Besides, with the D/S increasing, the adsorption efficiency increases and it is independent of the adsorption temperature. Ash particle size also has large influence on the adsorption efficiency, the smaller the particle size is, the larger the adsorption efficiency is. And when the flue gas speed rose, gas residence time correspondingly reduced and the adsorption efficiency dropped. However, since gas residence time is short in engineering applications, the influence of gas residence time is quite moderate. Furthermore, the adsorption of the sulfuric acid mist will cause a significant agglomeration between ash particles, and it has great significance to the removal of PM.

关键词： Low-low temperature flue gas system sulfuric acid mist adsorption characteristics

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Solubilities of CO_2, CH_4,H_2,CO and N_2 in choline chloride/urea

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Green Energy & Environment 2016年第3期1卷 195-200页

作者： Yujiao Xie Haifeng Dong Suojiang Zhang Xiaohua Lu Xiaoyan Ji Energy Engineering Division of Energy Science Lulea University of Technology Beijing Key Laboratory of Ionic Liquids Clean Process State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences Key Laboratory of Material and Chemical Engineering Nanjing Tech University

Solubilities of CO_2, CH_4, H_2, CO and N_2 in choline chloride/urea(ChCl/Urea) were investigated at temperatures ranging from 308.2 to328.2 K and pressures ranging from 0.6 to 4.6 MPa. The results show that the solubilities of gases increase with increasing pressure and decreasing temperature. The solubility of CO_2 is higher than that of CH_4, H_2, CO and N_2, which indicates that ChCl/Urea may be used as a potential solvent for CO_2 capture from the gas mixture. Solubility of CO_2 in ChCl/Urea was fitted by Non-Random Two-Liquid and Redlich-Kwong(NRTL-RK) model, and solubility of CH_4, H_2, CO or N_2 in ChCl/Urea was fitted by Henry's Law. The standard enthalpy, standard Gibbs energy and standard entropy of gases were calculated. Additionally, the CO_2/CH_4 selectivities in water, dry ChCl/Urea and aqueous ChCl/Urea were further discussed.

关键词： Gas solubility Choline chloride Urea CO2 separation

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Carbon Exergy Footprint to Evaluate the Greenhouse Impact of Operating Units

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Energy Procedia 2017年 105卷 3179-3184页

作者： Zhen Qin Xiaomei Wu Zaoxiao Zhang School of Chemical Engineering and Technology Xi’an Jiaotong University No.28 Xianning West Road Xi’an 710049 P.R. China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University No.28 Xianning West Road Xi’an 710049 P.R. China

Increasingly serious global warming caused by greenhouse gases has urged more and more focus on the sustainability. Exergy and carbon footprint are generally considered as two separate indicators to assess the greenhouse effect and sustainability of industrial production. In this paper we propose carbon exergy footprint (CEF) for quantitatively associating carbon footprint with exergy to evaluate the greenhouse effect of operating units. The indicator synthesizes the advantages of exergy and carbon footprint. Specific physical meaning for this novel indicator is illustrated on the basis of the second law of thermodynamics and life cycle assessment. The process of water-gas shift is chosen as the case for elaborating the behavior of CEF. Results show that CEF is competent for the objective evaluation for the greenhouse effect of the operating units. Additionally, CEF also maintains consistency with the conventional exergy analysis in terms of sustainability.

关键词： Carbon exergy footprint operating unit greenhouse impact indicator

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Platinum-based selective electrocatalysts for direct methanol fuel running at high-concentration methanol

Platinum-based selective electrocatalysts for direct methano...

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第二届中国（国际）能源材料化学研讨会

作者： Yan Feng Hui Liu Jun Yang State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences University of Chinese Academy of Sciences

engineering the structure of nanoscale materials is an effective way to control their properties for the enhancement of their performance for a given ***,we demonstrate the design and fabrication of platinum(Pt)-based... 详细信息

关键词： Platinum-based selective electrocatalysts for direct methanol fuel running at high-concentration methanol

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Integration of coal pyrolysis process with iron ore reduction： Reduction behaviors of iron ore with benzene-containing coal pyrolysis gas as a reducing agent

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Chinese Journal of Chemical engineering 2016年第6期24卷 811-817页

作者： Xin Li Helong Hui Songgeng Li Lu He Lijie Cui State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

An integrated coal pyrolysis process with iron ore reduction is proposed in this article. As the first step, iron oxide reduction is studied in a fixed bed reactor using simulated coal pyrolysis gas with benzene as a model tar compound. Variables such as reduction temperature, reduction time and benzene concentration are studied. The carbon deposition of benzene results in the retarded iron reduction at low temperatures. At high temperatures over800 °C, the presence of benzene in the gas can promote iron reduction. The metallization can reach up to 99% in20 min at 900 °C in the presence of benzene. Significant increases of hydrogen and CO/CO2 ratio are observed in the gas. It is indicated that iron reduction is accompanied by the reforming and decomposition of benzene. The degree of metallization and reduction increases with the increasing benzene concentration. Iron oxide can nearly completely be converted into cementite with benzene present in the gas under the experimental conditions. No sintering is found in the reduced sample with benzene in the gas.

关键词： Coal pyrolysisIron reductionIntegrationTar effect

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Overall Mass Transfer Coefficient of CO 2 Absorption in a Diameter-varying Spray Tower

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Energy Procedia 2017年 114卷 1665-1670页

作者： Xiaomei Wu Min He Yunsong Yu Zhen Qin Zaoxiao Zhang School of Chemical Engineering and Technology Xi’an Jiaotong University No.28 Xianning West Road Xi’an 710049 P.R. China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University No.28 Xianning West Road Xi’an 710049 P.R. China

The application of spray towers for CO 2 capture is a development trend in recent years. However, most of the previous jobs were conducted in a cylindrical tower by using a single spray nozzle, whose configuration and performance is not good enough for industrial application. To solve this problem, the present work proposed a diameter-varying spray tower and a new spray mode of dual-nozzle opposed impinging spray to enhance the absorption performance of CO 2 spray absorption process. Experiments were conducted to investigate the effects of varies operating parameters on the overall mass transfer coefficient in various operating conditions. Experimental results showed that liquid to gas ratio and mole ratio of MEA to CO 2 are key factors which affect the performance of CO 2 absorption process and the maximum overall mass transfer coefficient for the diameter-varying dual-nozzle opposed impinging spray tower is 0.4773 kmol·m -3 ·h -1 ·kPa -1 .

关键词： CO 2 capture diameter-varying spray tower overall mass transfer coefficient absorption performance

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