检索结果-南通市图书馆

Energy and AI 2024年第2期16卷 101-110页

作者： Franz M.Rohrhofer Stefan Posch Clemens Gößnitzer JoséM.García-Oliver Bernhard C.Geiger Know-Center GmbH Sandgasse 36Graz8010StyriaAustria LEC GmbH Inffeldgasse 19Graz8010StyriaAustria Universitat Politècnica de València Camíde VeraValència46022ValènciaSpain

Artificial Neural Networks(ANNs)have emerged as a powerful tool in combustion simulations to replace memory-intensive tabulation of integrated chemical *** reaction mechanisms,however,present a challenge for standard ANN approaches as modeling multiple species typically suffers from inaccurate predictions on minor *** paper presents a novel ANN approach which can be applied on complex reaction mechanisms in tabular data form,and only involves training a single ANN for a complete reaction *** approach incorporates a network architecture that automatically conserves mass and employs a particular loss weighting based on species *** modifications are used to improve the overall ANN performance and individual prediction accuracies,especially for minor species mass *** validate its effectiveness,the approach is compared to standard ANNs in terms of performance and ANN *** distinct reaction mechanisms(H_(2),C_(7)H_(16),C_(12)H_(26),OME_(34))are used as a test cases,and results demonstrate that considerable improvements can be achieved by applying both modifications.

关键词： Neural network approach chemical kinetics Flamelet tabulation Mass conservation Species loss weighting

A data-driven reduced-order model for stiff chemical kinetics using dynamics-informed training

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Energy and AI 2024年第1期15卷 181-192页

作者： Vijayamanikandan Vijayarangan Harshavardhana A.Uranakara Shivam Barwey Riccardo Malpica Galassi Mohammad Rafi Malik Mauro Valorani Venkat Raman Hong G.Im CCRC King Abdullah University of Science and TechnologyThuwalSaudi Arabia Argonne Leadership Computing Facility Argonne National LaboratoryLemontIL 60439USA Mechanical and Aerospace Engineering Department Sapienza University of RomeVia Eudossiana18Rome 00184Italy Department of Aerospace Engineering University of MichiganAnn ArborMI 48109USA

A data-based reduced-order model(ROM)is developed to accelerate the time integration of stiff chemically reacting systems by effectively removing the stiffness arising from a wide spectrum of chemical time ***,the objective of this work is to develop a ROM that acts as a non-stiff surrogate model for the time evolution of the thermochemical state vector(temperature and species mass fractions)during an otherwise highly stiff and nonlinear ignition *** model follows an encode-forecast-decode strategy that combines a nonlinear autoencoder(AE)for dimensionality reduction(encode and decode steps)with a neural ordinary differential equation(NODE)for modeling the dynamical system in the AE-provided latent space(forecasting step).By means of detailed timescale analysis by leveraging the dynamical system Jacobians,this work shows how data-based projection operators provided by autoencoders can inherently construct the latent spaces by removing unnecessary fast timescales,even more effectively than physics-based counterparts based on an eigenvalue analysis.A key finding is that the most significant degree of stiffness reduction is achieved through an end-to-end training strategy,where both AE and neural ODE parameters are optimized simultaneously,allowing the discovered latent space to be *** addition to end-to-end training,this work highlights the vital contribution of AE nonlinearity in the stiffness reduction *** the prediction of homogeneous ignition phenomena for H2-air and C2H4-air mixtures,the proposed ROM achieves several ordersof-magnitude increase in the integration time step size when compared to(a)a baseline CVODE solver for the full-chemical system,(b)statistical technique–principal component analysis(PCA),and(c)computational singular perturbation(CSP),a vetted physics-based stiffness-reducing modeling framework.

关键词： Stiff system chemical kinetics Reacting flows Autoencoders Neural ODE

chemical kinetics for NO Emissions in System of Methane-Air Turbulent-Jet Diffusion Flame

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Transactions of Tianjin University 2006年第6期12卷 404-409页

作者：姜斌梁红英黄国强李鑫钢 School of chemical Engineering and Technology Tianjin University

An explicit expression for local, instantaneous NO production rate model was proposed to simulate NO formation in turbulent methane-air combustion. The average production rates of mixture fraction and scalar dissipation were obtained from asymptotes through approximation of two single-variable probability-density function. The theory predicted significant contributions from the Zeldovich mechanism, but negligible contributions from the nitrous-oxide mechanism in the oxygenconsumption zone. The proposed model was used to simulate NO formation in the pilot methane-air jet diffusion combustion. The simulation results were compared with those obtained by the CFD software FLUENT module. Validation of predictions with the experimental data given by Sandia National Laboratory of the USA indicates that the proposed model yields better results than other models, and the deviation is under 5%. And in some complete reaction zones, the simulation results are even the same as the experimental data. Realizable κ-ε model, Reynold stress model and standard κ-ε model were also investigated to predict the turbulent combustion reaction, which shows that the simulation results of velocities, temperatures, and concentrations of combustion productions by standard κ-ε model are in accordance with the experimental data.

关键词： NO formation chemical kinetics turbulent model oxygen atom equation

A tool model for predicting atmospheric chemical kinetics with sensitivity analysis

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2001年第1期13卷 79-86页

作者： SHEN Ji (Research Center for Eco\|Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.E\|mail:shenji@***) Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China. shenji@***

A package(a tool model) for program of predicting atmospheric chemical kinetics with sensitivity analysis is presented. The new direct method of calculating the first order sensitivity coefficients using sparse matrix technology to chemical kinetics is included in the tool model, it is only necessary to triangularize the matrix related to the Jacobian matrix of the model equation. The Gear type procedure is used to integrate a model equation and its coupled auxiliary sensitivity coefficient equations. The FORTRAN subroutines of the model equation, the sensitivity coefficient equations, and their Jacobian analytical expressions are generated automatically from a chemical mechanism. The kinetic representation for the model equation and its sensitivity coefficient equations, and their Jacobian matrix is presented. Various FORTRAN subroutines in packages, such as SLODE, modified MA28, Gear package, with which the program runs in conjunction are recommended. The photo\|oxidation of dimethyl disulfide is used for illustration.

关键词： atmospheric chemical model chemical kinetics sensitivity analysis

Nanotechnology combining photoacoustic kinetics and chemical kinetics for thrombosis diagnosis and treatment

在线全文

学校读者我要写书评

暂无评论

Chinese chemical Letters 2021年第12期32卷 3665-3674页

作者： Hao Tian Lin Lin Zhaojing Ba Fangchao Xue Yanzhao Li Wen Zeng Department of Cell Biology Army Medical UniversityChongqing 400038China Department of Anatomy Army Medical UniversityChongqing 400038China Departments of Neurology Southwest HospitalArmy Medical UniversityChongqing 400038China

Thrombotic disease is a major problem that endangers human health. At present, MRI and CT are commonly used clinically to diagnose thrombosis, and thrombolytic drugs are used for treatment), but the diagnosis time is lagging, the utilization of drugs is low, and the resulting systemic toxicity problems such as side effects lead to poor treatment effects. Nanotechnology combining photoacoustic dynamics and chemical dynamics has shown great application value in tumor targeting, diagnosis, detection and treatment. It has also become a new direction in the diagnosis and treatment of thrombotic diseases, and has created new applications in the field of nanomaterials. This review summarizes the new progress of this combination in the diagnosis and treatment of thrombotic diseases according to the differences in the construction of the nanotherapy system, at the same time, we put forward some new problems and prospects for the integration of thrombosis diagnosis and treatment.

关键词： Nanotechnology Photoacoustic kinetics chemical kinetics Drug delivery and release Thrombosis disease

Comparison of Invariant Manifolds for Model Reduction in chemical kinetics

在线全文

学校读者我要写书评

暂无评论

Communications in Computational Physics 2007年第5期2卷 964-992页

作者： Eliodoro Chiavazzo Alexander N.Gorban Iliya V.Karlin Aerothermochemistry and Combustion Systems Laboratory LAV ETH Zurich8092 ZurichSwitzerland Department of Mathematics University of LeicesterLeicester LE17RHUK.

A modern approach to model reduction in chemical kinetics is often based on the notion of slow invariant *** goal of this paper is to give a comparison of various methods of construction of slow invariant manifolds using a simple Michaelis-Menten catalytic *** explore a recently introduced Method of Invariant Grids(MIG)for iteratively solving the invariance *** initial approximations for the grid are considered such as Quasi Equilibrium Manifold,Spectral Quasi Equilibrium Manifold,Intrinsic Low Dimensional Manifold and Symmetric Entropic Intrinsic Low Dimensional *** invariant manifold was also computed using the Computational Singular Perturbation(CSP)method.A comparison between MIG and CSP is also reported.

关键词： chemical kinetics model reduction invariant manifold entropy nonlinear dynamics mathematical modeling.

Modeling of Soot Formation in Gas Burner Using Reduced chemical kinetics Coupled with CFD Code

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of chemical Engineering 2010年第6期18卷 967-978页

作者： ZHANG Yindi ZHOU Huaichun XIE Mingliang FANG Qingyan WEI Yan State Key Laboratory of Coal Combustion Huazhong University of Science and Technology Wuhan 430074 China

A computational study of soot formation in ethylene/air coflow jet diffusion flame at atmospheric pres-sure was conducted using a reduced mechanism and soot formation model. A 20-step mechanism was derived from the full mechanism using sensitivity analysis,reaction path analysis and quasi steady state(QSS) approximation. The model in premixed flame was validated and with computing savings in diffusion flame was applied by incor-porating into a CFD code. Simulations were performed to explore the effect of coflow air on flame structure and soot formation. Thermal radiation was calculated by a discrete-ordinates method,and soot formation was predicted by a simple two-equation soot model. Model results are in good agreement with those from experiment data and detailed mechanism at atmospheric conditions. The soot nucleation,growth,and oxidation by OH are all enhanced by decrease in coflow air velocity. The peak soot volume fraction region appears in the lower annular region be-tween the peak flame temperature and peak acetylene concentration locations,and the high soot oxidation rate due to the OH attack occurs in the middle annular region because of high temperature.

关键词： modeling chemical kinetics sensitivity analysis soot formation

Rebuilding the theory of isotope fractionation for evaporation of silicate melts under vacuum condition

在线全文

学校读者我要写书评

暂无评论

Acta Geochimica 2024年第4期43卷 661-676页

作者： Jie Wang Yun Liu Research Center for Planetary Science College of Earth and Planetary SciencesChengdu University of TechnologyChengdu 610059China State Key Laboratory of Ore Deposit Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China CAS Center for Excellence in Comparative Planetology Hefei 230026China

Isotope eff ects are pivotal in understanding silicate melt evaporation and planetary accretion *** on the Hertz-Knudsen equation,the current theory often fails to predict observed isotope fractionations of laboratory experiments due to its oversimplified ***,we point out that the Hertz-Knudsen-equation-based theory is incomplete for silicate melt evaporation cases and can only be used for situations where the vaporized species is identical to the one in the *** propose a new model designed for silicate melt evaporation under *** model considers multiple steps including mass transfer,chemical reaction,and *** derivations reveal a kinetic isotopic fractionation factor(KIFF orα)αour model=[m(^(1)species)/m(^(2)species)]^(0.5),where m(species)is the mass of the reactant of reaction/nucleation-limiting step or species of diffusion-limiting step and superscript 1 and 2 represent light and heavy isotopes,*** model can eff ectively reproduce most reported KIFFs of laboratory experiments for various elements,i.e.,Mg,Si,K,Rb,Fe,Ca,and ***,the KIFF-mixing model referring that an overall rate of evaporation can be determined by two steps jointly can account for the eff ects of low P_(H2)pressure,composition,and *** addition,we find that chemical reactions,diffusion,and nucleation can control the overall rate of evaporation of silicate melts by using the fitting slope in ln(−ln f)versus ln(t).Notably,our model allows for the theoretical calculations of parameters like activation energy(E_(a)),providing a novel approach to studying compositional and environmental eff ects on evaporation processes,and shedding light on the formation and evolution of the proto-solar and Earth-Moon systems.

关键词： Evaporation Kinetic isotopic fractionation chemical kinetics Hertz-Knudsen equation CAIS

Experimental investigation on the NO formation of pulverized coal combustion under high-temperature and low-oxygen environments simulating MILD oxy-fuel combustion conditions

在线全文

学校读者我要写书评

暂无评论

Carbon Resources Conversion 2024年第3期7卷 84-96页

作者： Lanbo Li Yuegui Zhou Chaoqiang Yang Anwen Peng Guanshuo Huang Institute of Thermal Energy Engineering School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China

The NO formation experiments simulating moderate and intense low-oxygen dilution(MILD)oxy-coal combustion conditions were conducted on a laminar diffusion flame burner with the coflow temperatures of 1473-1873 K and the oxygen volume fractions of 5%-20%in O_(2)/CO_(2),O_(2)/Ar and O_(2)/N_(2)*** flame images of pulverized coal combustion were captured to obtain the ignition delay distances,and the axial species concentrations were measured to obtain the variation of NO formation and *** NO yield in O_(2)/Ar atmosphere decreased by nearly 0.2 when the oxygen volume fraction decreased from 20%to 5%and by about 0.05 when the coflow temperature decreased from 1873 K to 1473 *** NO yield in O_(2)/CO_(2)atmosphere was 0.1-0.15 lower than that in O_(2)/Ar *** optimal kinetic parameters of thermal NO and fuel NO formation rate were obtained by a nonlinear fit of nth-order Arrhenius ***,the relative contribution rates of thermal NO to total NO(Rth)and NO reduction to fuel NO(Rre)were quantitatively *** decreases with the increase of oxygen volume fraction,below 6%at 1800 K,25%at 2000 *** is almost unaffected by the coflow temperature and affected by the oxygen volume fraction,reaching 30%at 5%O_(2).

关键词： Pulverized coal combustion MILD oxy-fuel combustion NO formation and reduction chemical kinetics Relative contribution

Theoretical estimation of sonochemical yield in bubble cluster in acoustic field

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2020年第1期29卷 357-365页

作者： Zhuang-Zhi Shen School of Physics&Information Technology Shaanxi Normal UniversityShaanxi Key Laboratory of UltrasonicsXi'an 710119China

In order to learn more about the physical phenomena occurring in cloud cavitation,the nonlinear dynamics of a spherical cluster of cavitation bubbles and cavitation bubbles in cluster in an acoustic field excited by a square pressure wave are numerically investigated by considering viscosity,surface tension,and the weak compressibility of the *** theoretical prediction of the yield of oxidants produced inside bubbles during the strong collapse stage of cavitation bubbles is also *** effects of acoustic frequency,acoustic pressure amplitude,and the number of bubbles in cluster on bubble temperature and the quantity of oxidants produced inside bubbles are *** results show that the change of acoustic frequency,acoustic pressure amplitude,and the number of bubbles in cluster have an effect not only on temperature and the quantity of oxidants inside the bubble,but also on the degradation types of pollutants,which provides a guidance in improving the sonochemical degradation of organic pollutants.

关键词： bubble cluster models bubble cluster dynamics chemical kinetics bubble temperature strong oxidants acoustic cavitation