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Co-conversion of methanol and n-hexane into aromatics using intergrown ZSM-5/ZSM-11 as a catalyst

Frontiers of Chemical Science and Engineering 2020年第5期14卷 783-792页

作者： Shumei Wei Yarong xu Zhaoyang Jin xuedong Zhu UNILAB State Key Laboratory of Chemical EngineeringEast China University of Science and TechnologyShanghai 200237China Research Institute of Urumqi Petrochemical Company Petrochina Company LimitedUrumqi 830019China

The conversion of n-hexane and methanol into value-added aromatic compounds is a promising method for their industrially relevant *** this study,intergrown ZSM-5/ZSM-11 crystals were synthesized and their resulting catalytic performance was investigated and compared to those of the isolated ZSM-5 and ZSM-1I *** physicochemical properties of ZSM-5/ZSM-l1 intergrown zeolite were analyzed using X-ray diffrac-tion,N2 isothermal adsorption-desorption,the tempera-ture-programmed desorption of ammonium,scanning clectron microscopy,Fourier transform infrared spectra of adsorbed pyridine,and nuclear magnetic resonance of 27AI,and compared with those of the ZSM-5 and ZSM-11 *** catalytic performances of the materials were evaluated during the co-feeding reaction of methanol and n-hexane under the fixed bed conditions of 400℃,0.5 MPa(N2),methanol:n-hexane=7:3(mass ratio),and weight hourly space velocity=1 h 1(methanol).Com-pared to the ZSM-5 and ZSM-11 zeolites,the ZSM-5/ZSM-11 zeolite exhibited the largest specific surface area,a unique crystal structure,moderate acidity,and suitable Brensted/Lewis acid *** evaluation results showed that ZSM-5/ZSM-11 catalyst exhibited better catalytic reactivity than the ZSM-5 and ZSM-11 catalysts in terms of methanol conversion rate,n-hexane conversion rate,and aromatic *** outstanding catalytic property of the intergrown ZSM-5/ZSM-11 was attributed to the enhanced diffusion associated with its unique *** benefit of using zeolite intergrowth in the co-conversion of methanol and alkanes offers a novel route for future catalyst development.

关键词： ZSM-5/ZSM-11 methanol w-hexane cofeeding aromatics

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Prediction of nonlinear pilot-induced oscillation using an intelligent human pilot model

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Chinese Journal of Aeronautics 2019年第12期32卷 2592-2611页

作者： Shuting xu Wenqian TAN Xiangju QU Cheng ZHANG School of Aeronautic Science and Engineering Beihang University

This paper proposes a method to predict nonlinear Pilot-Induced Oscillation(PIO)using an intelligent human pilot *** method is based on a scalogram-based PIO metric,which uses wavelet transforms to analyze the nonlinear characteristics of a time-varying *** intelligent human pilot model includes three modules:perception module,decision and adaptive module,and execution *** and adaptive features,including a neural network receptor,fuzzy decision and adaptation,are also introduced into the human pilot model to describe the behavior of the human pilot accommodating the nonlinear ***,an algorithm is proposed to describe the procedure of the PIO prediction method with nonlinear evaluation *** prediction results obtained by numerical simulation are compared with the assessments of flight test data to validate the utility of the *** flight test data were generated in the evaluation of the Smart-Cue/Smart-Gain,which is capable of reducing the PIO tendencies *** results show that the method can be applied to predict the nonlinear PIO events by human pilot model simulation.

关键词： Pilot-induced oscillation Human pilot model Flight simulation Human-vehicle system Nonlinear system

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Ferroelectric Oxide Nanocomposites with Trimodal Pore Structure for High Photocatalytic Performance

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Nano-Micro Letters 2019年第3期11卷 5-20页

作者： Tingting xu xuan Liu Shulan Wang Li Li Department of Chemistry School of ScienceNortheastern UniversityShenyang110819People’s Republic of China School of Metallurgy Northeastern UniversityShenyang110819People’s Republic of China

An effective method to improve the photocatalytic performances of powder catalysts is to use the internal electric field from ferroelectrics to separate photogenerated charge *** design and engineering of a complex hetero-junction with a hierarchical pore structure is highly desirable for the efficient application of ferroelectric materials in ***,we present a novel strategy using two templates to fabricate PbTiO3/TiO2/carbon(PTC)nanocomposites with a tunable microstructure.A hard SiO2 template combined with an ice template followed by an appropriate pyrolysis procedure introduced trimodal(micro-,meso-,macro-)*** as-prepared PTC nanocomposites with optimal mass ratio exhibited excellent photocatalytic and photoelectrochemical ***3/TiO2 annealed at 900 ℃(PTC-900)showed a MB degradation rate of 0.21 and 0.021 min-1 under UV and visible light irradiation,which are,respectively,7.2 and3 times those of pure *** photocurrent density of the composite catalyst is 1.48 mA cm-2 at the potential of 1.0 V versus saturated calomel electrode,and the rates of hydrogen generation of PTC-900 are as high as 2360 and 9.6 μmol h-1 g-1 under UV and visible light irradiation,*** importantly,the simultaneous application of ultrasound-induced mechanical waves further improved the photocatalytic *** work serves to improve understanding on the design of ferroelectric/piezoelectric photocatalysts with a hierarchical pore structure and also proposes a widely applicable strategy for the fabrication of high-performance micro-nano/nano-nano structures.

关键词： Ferroelectric photocatalysis Piezoelectric Hierarchical pores Photocatalytic hydrogen production Triple-junction

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Initial result of the Chinese Deep Space Stations' coordinates from Chinese domestic VLBI experiments

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Science China(Information Sciences) 2017年第1期60卷 170-176页

作者： Guangliang DONG Dezhen xu Haitao LI Huan ZHOU Beijing Institute of Tracking and Telecommunications Technology

China's Lunar Exploration Program(CLEP) prompted the design and construction of the globally distributed Chinese Deep Space Network(CDSN). This network consists of Jiamusi and Kashi stations in China, and Zapala station in Argentina. However, the positions of Jiamusi and Kashi are not accurate enough for future Chinese deep space missions, and geodetic Very Long Baseline Interferometry(VLBI) is the most effective way to determine their positions. Since the CDSN stations are equipped with narrow-band receivers,they cannot participate in current international VLBI sessions in which wide-band frequencies are utilized. Thus a cooperative geodetic program of the CDSN and Chinese VLBI Network(CVN, the VLBI tracking subsystem of the CLEP) was initiated to determine their positions, in which specially designed frequencies can be utilized,and some CVN stations can act as position reference stations owing to their precise positions from long-term international VLBI observations. Primary results have been obtained from the CDSN–CVN combined domestic VLBI experiments from September 28, 2014, through December 10, 2015. The positions of Jiamusi and Kashi are determined to be better than 10-mm precision in the X, Y, and Z directions, which are improved by a factor of approximately 20 over their a priori values.

关键词： VLBI Chinese Deep Space Network Chinese VLBI Network station position determination terrestrial reference frame

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Early changes in white blood cell,C-reactive protein and procalcitonin levels in children with severe multiple trauma

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World Journal of Emergency Medicine 2022年第6期13卷 448-452页

作者： Cai-fang xu Ming-chao Huo Jin-hui Huang Chun-feng Liu Wei xu The Pediatrics Department Shengjing Hospital of China Medical UniversityShenyang 110004China Department of Critical Care Medicine Shanghai Children’s HospitalShanghai Jiao Tong University School of MedicineShanghai 200062China

BACKGROUND:To analyze early changes in white blood cells(WBCs),C-reactive protein(CRP)and procalcitonin(PCT)in children with multiple trauma,before secondary inflammation ***:This single-center retrospective study collected data from patients with blunt traumatic injury admitted to the pediatric intensive care unit(PICU).According to the prognostic outcome of 28 d after admission to the PICU,patients were divided into survival group(n=141)and non-survival group(n=36).Characteristics between the two groups were *** operation characteristic(ROC)curve analysis was conducted to evaluate the capacity of different biomarkers as predictors of ***:The percentages of children with elevated WBC,CRP,and PCT levels were 81.36%,31.07%,and 95.48%,*** in the non-survival group presented a statistically significantly higher injury severity score(ISS)than those in the survival group:37.17±16.11 vs.22.23±11.24(t=6.47,P<0.01).WBCs were also higher in non-survival group than in the survival group([18.70±8.42]×109/L vs.[15.89±6.98]×109/L,t=2.065,P=0.040).There was no significant difference between the survival and non-survival groups in PCT or *** areas under the ROC curves of PCT,WBC and ISS for predicting 28-day mortality were 0.548(P=0.376),0.607(P=0.047)and 0.799(P<0.01),***:Secondary to multiple trauma,PCT levels increased in more patients,even if their WBC and CRP levels remained ***,early rising WBC and ISS were superior to PCT at predicting the mortality of multiple trauma patients in the PICU.

关键词： Pediatric Procalcitonin Injury severity score Multiple trauma

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CFD simulation of internal-loop airlift reactor using EMMS drag model

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Particuology 2015年第2期13卷 124-132页

作者： Tingting xu xuedong Jiang Ning Yang Jiahua Zhu State Key Laboratory of Multi-Phase Complex Systems Institute of Process EngineeringChinese Academy of Sciences University of Chinese Academy of Sciences Department of Chemical Engineering Xi'an Jiaotong University School of Chemical Engineering Sichuan University

The simulation of internal-loop airlift reactors is challenging because complex meso-scale structures exist in different sections of the reactor, separated by the draft tube. This paper reports on the computational fluid dynamics （CFD） simulation of internal-loop airlift reactors using a new drag model derived from the dual-bubble-size （DBS） model, an extended energy-minimization multi-scale （EMMS） approach for gas-liquid flows. Compared with the traditional Schiller-Naumann （S-N） correlation, the new model improves the simulation of gas holdup in the riser and downcomer significantly. In particular, gas holdup and circulation of two-phase flow can be modeled successfully using the new model, whereas traditional drag models such as the S-N correlation show an absence of gas in the downcomer. The simulation demonstrates the advantage and potential of this new model for internal-loop airlift reactors.

关键词： Computational fluid dynamics Internal-loop Airlift Multi-scale Multiphase flow Hydrodynamics

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Chatter stability prediction in four-axis milling of aero-engine casings with bull-nose end mill

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Chinese Journal of Aeronautics 2015年第6期28卷 1766-1773页

作者： Zhou xu Zhang Dinghua Luo Ming Wu Baohai Key Laboratory of Contemporary Design and Integrated Manufacturing Technology Ministry of EducationNorthwestern Polytechnical University

An analytical model for chatter aero-engine casings is presented in this paper stability prediction in bull-nose end milling of And the mechanics and dynamics variations due to the complex cutter and workpiece geometry are considered by analyzing the effects of the lead angle on the milling process. Firstly, the tool-workpiece engagement region is obtained by using a previously developed method and divided into several disk elements along the tool-axis direction. Secondly, a 3D dynamic model for stability limit calculation is developed and simplified into a 1D model in normal direction considering only the dominant mode of the workpiece. Then the cutting force coefficients, the start and exit angles corresponding to each disk element are determined. And the total stability lobe diagram is calculated using an iterative algorithm. Finally, several experimental tests are carried out to validate the feasibility and effectiveness of the proposed ~rediction approach.

关键词： Aero-engine casings Bull-nose end mill Chatter Four-axis milling Stability lobe diagram

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Application of Active Flow Control Technique for Gust Load Alleviation

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Chinese Journal of Aeronautics 2011年第4期24卷 410-416页

作者： xu Xiaoping ZHU Xiaoping ZHOU Zhou FAN Ruijun National Key Laboratory of Science and Technology on UAV Northwestern Polytechnical University Xi 'an 710072 China Research Institute of Unmanned Aerial Vehicle Northwestern Polytechnical University Xi 'an 710072 China

A new gust load alleviation technique is presented in this paper based on active flow control. Numerical studies are conducted to investigate the beneficial effects on the aerodynamic characteristics of the quasi ＂Global Hawk＂ airfoil using arrays of jets during the gust process. Based on unsteady Navier-Stokes equations, the grid-velocity method is introduced to simulate the gust influence, and dynamic response in vertical gust flow perturbation is investigated for the airfoil as well. An unsteady surface transpiration boundary condition is enforced over a user specified portion of the airfoil’s surface to emulate the time dependent velocity boundary conditions. Firstly, after applying this method to simulate typical NACA0006 airfoil gust response to a step change in the angle of attack, it shows that the indicial responses of the airfoil make good agreement with the exact theoretical values and the calculated values in references. Furthermore, gust response characteristic for the quasi ＂Global Hawk＂ airfoil is analyzed. Five kinds of flow control techniques are introduced as steady blowing, steady suction, unsteady blowing, unsteady suction and synthetic jets. The physical analysis of the influence on the effects of gust load alleviation is proposed to provide some guidelines for practice. Numerical results have indicated that active flow control technique,as a new technology of gust load alleviation, can affect and suppress the fluid disturbances caused by gust so as to achieve the purpose of gust load alleviation.

关键词： active flow control gust response gust alleviation numerical simulation aerodynamics unsteady flow airfoil

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Biomimetic Material Simulating Solar Spectrum Reflection Characteristics of Yellow Leaf

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Journal of Bionic Engineering 2018年第4期15卷 741-750页

作者： Kai xu Yang Lin xuezhong Wei Hong Ye Department of Thermal Science and Energy Engineering University of Science and Technology of China Hefei 230027 China Beijing Institute of Space Launch Technology Beijing 100076 China

To counter the threat of hyperspectral detection, it is necessary to develop biomimetic materials to simulate the solar spectral re- flection characteristics of plant leaf accurately. Two kinds ofmembranaceous yellow biomimetic materials were prepared by dispersing the particles of chrome titanium yellow and iron oxide yellow as fillers in polyvinyl alcohol films respectively. Reflectance and transmittance of the biomimetic materials were measured, and absorption and scattering coefficients of the biomimetic materials were inverted with a four-flux model. Results indicate that the biomimetic material adopting chrome titanium yellow particles can simulate the solar spectrum reflection characteristics of yellow leaf because of the similar absorption and scattering characteristics. The biomimetic material adopting iron oxide yellow particles cannot simulate the spectrum reflection characteristics of yellow leaf near the wavelength of 900 nm due to the characteristic absorption of the iron oxide. When the volume fraction of the chrome titanium yellow particles is lower than 2.12%, the absorption and scattering coefficients both increase approximately linearly with the volume fraction, indicating that the particles can scatter radiation independently. Therefore, the reflectance of the biomimetic material can be regulated through linearly changing of the volume fraction of the chrome titanium yellow particles.

关键词： biomimetic material yellow leaf solar spectrum reflection four-flux model absorption coefficient scattering coefficient

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Finite-time stabilization of switched dynamical networks with quantized couplings via quantized controller

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Science China(Technological Sciences) 2018年第2期61卷 299-308页

作者： YANG XinSong CAO JinDe xu Chen FENG JianWen School of Mathematical Sciences Chongqing Normal UniversityChongqing 401331China School of Mathematics and Research Center for Complex Systems and Network SciencesSoutheast UniversityNanjing 210096China College of Mathematics and Statistics Shenzhen UniversityShenzhen 518060China

This paper concerns the stabilization of switched dynamical networks with logarithmic quantization couplings in a settling *** switching sequence is constrained by hybrid dwell time. Controller is designed by using limited information. Due to the quantization and switching, traditional finite-time analysis methods cannot be utilized directly. By designing multiple Lyapunov functions and constructing comparison systems, a general criterion formulated by matrix inequalities is first given. Then specific conditions in terms of linear matrix inequalities are established by partitioning the dwell time and using convex combination technique. An optimal algorithm is proposed for the estimation of settling time. Numerical simulations are given to verify the effectiveness of the theoretical results.

关键词： dwell time finite time quantized couplings quantized controller switching

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