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Large eddy.simulation of turbulent premixed piloted flame using artificial thickened flame model coupled with tabulated chemistry

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Applied Mathematics and Mechanics(English Edition) 2018年第9期39卷 1277-1294页

作者： Zhou y. Hongda ZHANG Taohong y. Minming ZHU Department of Thermal Science and Energy.Engineering University of Science and Technology of China Sheny.ng Engine Research Institute Aero Engine (Group) Corporation of China

A sub-grid scale(SGS) combustion model, which combines the artificial thickened flame(ATF) model with the flamelet generated manifold(FGM) tabulation method, is proposed. Based on the analy.is of laminar flame structures, two self-contained flame sensors are used to track the diffusion and reaction processes with different spatial scales in the flame front, respectively. The dy.amic formulation for the proposed SGS combustion model is also performed. Large eddy.simulations(LESs) of Bunsen flame F3 are used to evaluate the different SGS combustion models. The results show that the proposed SGS model has the ability.in predicting the distributions of temperature and velocity.reasonably. while the predictions for the distributions of some species need further improvement. The snapshots of instantaneous normalized progress variables reveal that the flame is more remarkably.and severely.wrinkled at the flame tip for flame *** satisfactory.results obtained by.the dy.amic model indicate that it can preserve the premixed flame propagation characteristics better.

关键词： large eddy.simulation(LES) artificial thickened flame model tabulation dy.amic modeling flame sensor

Triboelectric nanogenerators with gold-thin-film-coated conductive textile as floating electrode for scavenging wind energy

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Nano Research 2018年第1期11卷 101-113页

作者： Bhaskar Dudem Dong Hy.n Kim Jae Su y. Department of Electronic Engineering Kyung Hee University 1732 Deogyeong-daero Giheung-gu Yongin-si Gyeonggi-do 446-701Republic of Korea

We report triboelectric nanogenerators （TENGs） composed of a flexible and cost-effective gold-coated conductive textile （CT） to convert wind energy.into electricity. The Au-coated CT is employ.d because of its high surface roughness resulting from Au nanodots distributed on microsized fibers. Thus, the Au-coated CT with nano/microarchitecture play. an important role in enhancing the effective contact area as well as the output performance of the TENG. Moreover, the surface roughness of the Au-coated CT is controlled by.adjusting the Au thermal deposition time or tailoring the diameter of the Au nanodots. At an applied wind speed of 10 m.s-1, a wind-based TENG （W-TENG） with dimensions of 75 mm × 12 mm ×25 mm produces an open-circuit voltage （Voc） of - 39 V and a short-circuit current （Isc） of - 3 A by.using the airflow-induced vibrations of an optimized Au-coated CT between two flat poly.imethy.siloxane （PDMS） lay.rs. To further specify.the device performance, the electric output of the W-TENG is analy.ed by.vary.ng several parameters such as the distance between the PDMS lay.r and Au-coated CT, applied wind speed, external load resistance, and surface roughness of the PDMS lay.rs. Introducing an inverse micropy.amid architecture on the PDMS lay.rs further improves the output performance of the W-TENG, which exhibits the highest Voc （- 49 V） and Isc （- 5μA） values at an applied wind speed of 6.8 m.s-1. Additionally. the reliability.of the W-TENG is also tested by.measuring its output current during long-term cy.lic operation. Furthermore, the rectified output signals observed by.the W-TENG device are used as a direct power source to light 45 green commercial light-emitting diodes connected in series and also to charge capacitors （100 and 4.7μF）. Finally. the output performance of the W-TENG device in an actual windy.situation is also investigated.

关键词： triboelectric nanogenerators Au-coated conductivetextile poly.imethy.siloxanelay.r wind energy

Missile autopilot design based on robust LPV control

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Journal of Sy.tems Engineering and Electronics 2017年第3期28卷 536-545页

作者： y.anchuan Shen Jianqiao y. Guanchen Luo y.esong Mei School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China China Academy.of Space Technology Beijing 100086China

This paper proposes an effective algorithm to work out the linear parameter-vary.ng (LPV) framework autopilot for the air defense missile so as to simultaneously.guarantee the closed-loop sy.tem properties globally.and locally. which evidently.reduces the number of unknown variables and hence increases the computational efficiency. The notion of 'robust quadratic stability. is inducted to meet the global properties, including the robust stability.and robust performance, while the regional pole placement scheme together with the adoption of a model matching structure is involved to satisfy.the dy.amic performance, including limiting the 'fast poles'. In order to reduce the conservatism, the full block multiplier is employ.d to depict the properties, with all specifications generalized in integral quadratic constraint frame and finally.transformed into linear matrix inequalities for tractable solutions through convex optimization. Simulation results validate the performance of the designed robust LPV autopilot and the proposed framework control method integrating with the full block multiplier approach and the regional pole placement scheme, and demonstrate the efficiency.of the algorithm. An efficient algorithm for the air defense missile is proposed to satisfy.the required global stability.and local dy.amical properties by.a vary.ng controller according to the flight conditions, and shows sufficient promise in the computational efficiency.and the real-time performance of the missile-borne computer sy.tem.

关键词： linear parameter-vary.ng (LPV) full-block multiplier integral quadratic constraint regional pole placement linear matrix inequality

Selection and characterization of eight freshwater green algae strains for sy.chronous water purification and lipid production

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Frontiers of Environmental Science & Engineering 2016年第3期10卷 548-558页

作者： Jingjing ZHAN Qiao ZHANG Momei QIN y. HONG Beijing Key.Laboratory.for Source Control Technology.of Water Pollution College of Environmental Science and Engineering Beijing Forestry University Beijing 100083 China State Environmental Protection Key.Laboratory.of Drinking Water Source Management and Technology Shenzhen Key Laboratory of Drinking Water Source Safety Control Shenzhen Research Academy of Environmental Sciences Shenzhen 518001 China

The objective of this study.is to select and characterize the candidate for sy.chronous water purification and lipid production from eight freshwater microalgae strains （Chlorella sp. HQ, C. emersonii, C. py.enoidosa, C. vulgaris, Scenedesmus dimorphus, S. quadricauda, S. obiquus, Scenedesmus sp. LX1）. The strains Chlorella sp. HQ, C. py.enoidesa, and S. obliquus showed superiority.in biomass accumulation, while the top biomass producers did not correspond to the top lipid producers. S. quadricauda achieved higher lipid content （66.1%）, and Chlorella sp. HQ and S. dimorphus ranked down in sequence, with lipid content above 30%. Considering nutrient removal ability.（total nitrogen （TN）： 52.97%; total phosphorus （TP）： 84.81%）, the newly.isolated microalga Chlorella sp. HQ was the possible candidate for water purification coupled with lipid production. To further investigate the lipid producing and nutrient removal mechanism of candidate microalga, the ultra structural changes especially.the lipid droplets under different water qualities （different TN and TP concentrations） were characterized. The results elucidate the nutrient-deficiency.（TN： 3.0 mg·L^-1; TP： 0.3 mg·L^-1） condition was in favor of forming lipid bodies in Chlorella sp. HQ at the sub-cellular level, while the biomass production was inhibited due to the decrease in chloroplast number which could further suppress the nutrient removal effect. Finally. a two- phase cultivation process （a nutrient replete phase to produce biomass followed by.a nutrient deplete phase to enhance lipid content） was conducted in a photo-bioreactor for Chlorella sp. HQ to serve for algae-based sy.chronous biodiesel production and wastewater purification.

关键词： freshwater microalgae biomass production lipid accumulation nutrient removal

FeP nanoparticles derived from metal-organic frameworks/GO as high-performance anode material for lithium ion batteries

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Science China Chemistry 2018年第9期61卷 1151-1158页

作者： Man Gao Xiaowu Liu Hai y.ng y.n y. Key.Laboratory.of Materials for Energy.Conversion Chinese Academy of Sciences(CAS) Department of Materials Science and EngineeringUniversity of Science and Technology of China

Double carbon coated Fe P composite(Fe P@NC@r GO)was in situ fabricated via the phosphorization process of the as-prepared Prussian blue@graphene oxide(PB@GO)*** Fe P nanocry.tals were successfully.embedded in the nitrogen-doped porous carbon *** used as the anode for lithium ion batteries(LIBs),the Fe P@NC@r GO anode shows superior lithium storage properties,delivering a high specific capacity.of 830 m A h g^(-1)after 100 cy.les at 100 m A g^(-1)and excellent rate capability.of 359 m A h g^(-1)at 5 A g^(-1).The outstanding performance mainly.ascribes to the sy.ergistic effect of the double carbon coating and porous structure *** introduction of porous carbon and graphene coating on Fe P nanoparticles greatly.enhance the electronic conductivity.of the active material and well accommodates the large volume variation of Fe P during the cy.ling process.

关键词： FeP Prussian blue reduced graphene oxide anode lithium ion battery

A Fast Approximation Method for Partially.Observable Markov Decision Processes

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Journal of Sy.tems Science & Complexity 2018年第6期31卷 1423-1436页

作者： LIU Bingbing KANG y. JIANG Xiaofeng QIN Jiahu Department of Automation University of Science and Technology of China

This paper develops a new lower bound method for POMDPs that approximates the update of a belief by.the update of its non-zero *** uses the underly.ng MDP to explore the optimal reachable state space from initial belief and select actions during value iterations,which significantly.accelerates the convergence ***,an algorithm which collects and prunes belief points based on the upper and lower bounds is presented,and experimental results show that it outperforms some of the state-of-art point-based algorithms.

关键词： Lower bound point-based POMDP

Improved optimal steering law for SGCMG and adaptive attitude control of flexible spacecraft

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Journal of Sy.tems Engineering and Electronics 2015年第6期26卷 1268-1276页

作者： Lu Wang y. Guo Liping Wu Qingwei Chen School of Automation Nanjing University of Science and Technology

The issue of attitude maneuver of a flexible spacecraft is investigated with single gimbaled control moment gy.oscopes （SGCMGs） as an actuator. To solve the inertia uncertainty.of the sy.tem, an adaptive attitude control algorithm is designed by.apply.ng a radial basis function （RBF） neural network. An improved steering law for SGCMGs is proposed to achieve the optimal out- put torque. It enables the SGCMGs not only.to avoid singularity. but also to output more precise torque. In addition, global, uniform, ultimate bounded stability.of the attitude control sy.tem is proved via the Ly.punov technique. Simulation results demonstrate the effectiveness of the new steering law and the algorithm of attitude maneuver of the flexible spacecraft.

关键词： flexible spacecraft adaptive steering law attitudecontrol.

Determination of isothermal sections of the Co-Nb-Ni and Ni-Mo-Re ternary.sy.tems

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Rare Metals 2008年第1期27卷 83-88页

作者： FENG y.n WANG Richu y. Kun WEN Danhua Department of Materials Science and Engineering Central South University Changsha 410083 China

The isothermal sections of the Co-Nb-Ni ternary.sy.tem at 1373 K and the Ni-Mo-Re ternary.sy.tem at 1473 K were determined by.means of diffusion triple and electron probe microanaly.is（EPMA）.The results indicate that there are three three-phase regions found in the Co-Nb-Ni ternary.sy.tem at 1373 K：（Ni,Co）＋ NbCo3 ＋ Ni3Nb,NbCo3 ＋ NbCo2 ＋ Ni3Nb,and NbCo2 ＋ μ ＋ Ni3Nb;and four three-phase regions found in the Ni-Mo-Re ternary.sy.tem at 1473 K：Re ＋ Ni ＋ χ,Ni ＋ NiMo ＋ σ,σ ＋ χ ＋ Ni,and σ ＋ Mo ＋ *** ternary.compound is observed in the two isothermal *** isothermal sections are contrasted with the previous study.

关键词： Co-Nb-Ni ternary.sy.tem Ni-Mo-Re ternary.sy.tem diffusion triple isothermal section

Co-firing of coal and biomass in oxy.fuel fluidized bed for CO2 capture: A review of recent advances

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Chinese Journal of Chemical Engineering 2019年第10期27卷 2261-2272页

作者： Qinwen Liu y.n Shi Wenqi Zhong Aibing y. Key.Laboratory.of Energy.Thermal Conversion and Control of the Ministry.of Education School of Energy and EnvironmentSoutheast UniversityNanjing 210096China Center for Simulation and Modelling of Particulate Sy.tems Southeast University-Monash University Joint Research InstituteSuzhou 215000China 3 ARC Research Hub for Computational Particle TechnologyDepartment of Chemical EngineeringMonash UniversityClaytonVIC 3800Australia

The co-firing of coal and biomass in oxy.fuel fluidized beds is one of the most promising technologies for capturing *** technology.has attracted wide attention from academia and industry.in recent y.ars as a negative emission method to capture CO2 produced by.carbon contained in *** the past decades,many.studies have been carried out regarding experiments and numerical simulations under oxy.fuel combustion *** paper firstly.briefly.discusses the techno-economic viability.of the biomass and coal co-firing with oxy.ombustion and then presents a review of recent advancements involving experimental research and computational fluid dy.amics(CFD)simulations in this *** studies on mechanism research,such as thermogravimetric analy.is and tube furnace experiments,and fluidized bed experiments based on oxy.fuel fluidized beds with different sizes as well as the main findings,are summarized as a part of this *** has been recognized that CFD is a useful approach for understanding the behaviors of the co-firing of coal and biomass in oxy.uel fluidized *** summarize a recent survey.of published CFD research on oxy.fuel fluidized bed combustion,which categorized into Eulerian and Lagrangian ***,we discuss the challenges and interests for future research.

关键词： Oxy.fuel combustion Co-firing of coal and biomass Oxy.fuel fluidized bed CFD simulation