检索结果-南通市图书馆

Approximations to Isentropic Planar Magneto-Hydrodynamics Equations by Relaxed Euler-Type Systems

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 2024年第3期45卷 413-440页

作者： Yachun LI zhaoyang SHANG Chenmu WANG liang zhao School of Mathematical Sciences CMA-ShanghaiMOE-LSC and SHL-MACShanghai Jiao Tong UniversityShanghai 200240China School of Finance Shanghai Lixin University of Accounting and FinanceShanghai 201209China School of Mathematical Sciences Shanghai Jiao Tong UniversityShanghai 200240China School of Mathematical Sciences Harbin Engineering UniversityHarbin 150001China Mathematical Modelling&Data Analytics Center Oxford Suzhou Centre for Advanced ResearchSuzhou 215123JiangsuChina

In this paper, the authors consider an approximation to the isentropic planar Magneto-hydrodynamics(MHD for short) equations by a kind of relaxed Euler-type system. The approximation is based on the generalization of the Maxwell law for nonNewtonian fluids together with the Maxwell correction for the Ampe`re law, hence the approximate system becomes a first-order quasilinear symmetrizable hyperbolic systems with partial dissipation. They establish the global-in-time smooth solutions to the approximate Euler-type equations in a small neighbourhood of constant equilibrium states and obtain the global-in-time convergence towards the isentropic planar MHD equations. In addition, they also establish the global-in-time error estimates of the limit based on stream function techniques and energy estimates for error variables.

关键词： Planar MHD equations Relaxation limits Global convergence Stream function

Computational fluid dynamics modeling of rapid pyrolysis of solid waste magnesium nitrate hydrate under different injection methods

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2024年第2期66卷 224-237页

作者： Wenchang Wu Kefan Yu liang zhao Hui Dong SEP Key Laboratory of Eco-industry School of MetallurgyNortheastern UniversityShenyang 110819China Liaoning Engineering Research Center of Energy Saving and Green Low Carbon Technology for Process Industry Northeastern UniversityShenyang 110819China

This study developed a numerical model to efficiently treat solid waste magnesium nitrate hydrate through multi-step chemical *** model simulates two-phase flow,heat,and mass transfer processes in a pyrolysis furnace to improve the decomposition rate of magnesium *** performance of multi-nozzle and single-nozzle injection methods was evaluated,and the effects of primary and secondary nozzle flow ratios,velocity ratios,and secondary nozzle inclination angles on the decomposition rate were *** indicate that multi-nozzle injection has a higher conversion efficiency and decomposition rate than single-nozzle injection,with a 10.3%higher conversion rate under the design *** decomposition rate is primarily dependent on the average residence time of particles,which can be increased by decreasing flow rate and velocity ratios and increasing the inclination angle of secondary *** optimal parameters are injection flow ratio of 40%,injection velocity ratio of 0.6,and secondary nozzle inclination of 30°,corresponding to a maximum decomposition rate of 99.33%.

关键词： Multi-nozzle Computational fluid dynamics Thermal decomposition reaction Pyrolysis furnace

Hourly land surface temperature retrieval over the Tibetan Plateau using Geo-LightGBM framework: Fusion of Himawari-8 satellite, ERA5 and site observations

在线全文

学校读者我要写书评

暂无评论

Advances in Climate Change Research 2024年第4期15卷 623-635页

作者： zhao-Hua LIU Shan-Shan WENG zhao-liang ZENG Ming-Hu DING Ya-Qiang WANG Zhehao liang Civil and Surveying&Mapping Engineering Jiangxi University of Science and TechnologyGanzhou 341000China State Key Laboratory of Severe Weather Chinese Academy of Meteoroogical Sciences Beijing 100081China Space Geodesy and Geoinformation Technical Unviersity of BerlinBerlin 10623Germany

The Tibetan Plateau(TP)is highly sensitive to even minor fluctuations in land surface temperature(LST),which can result in permafrost melting and degradation of alpine grasslands,leading to serious ecological ***,it is crucial to have high-temporal-resolution and seamless hourly estimating and monitoring of LST for a better understanding of climate change on the ***,we employed Himawari-8 satellite,Digital Elevation Model(DEM),ERA5 reanalysis and meteorological station observations data to develop a new LightGBM framework(called Geo-LightGBM)for estimating LST on the TP,and then analyzed the spatiotemporal variations of those ***-LightGBM demonstrated excellent LST estimation accuracy,with an R2(coefficient of determination)of 0.971,RMSE(root-mean-square error)of 2.479℃,and MAE(mean absolute error)of 1.510℃.The estimated LST values for the year 2020 agreed well with observed values,with remarkable differences in hourly LST ***,the estimated LST was more accurate than that from ***,there were two high LST centers,located in the Yarlung Zangbo River Basin and the Qaidam Basin,and a low LST center located in the central *** SHAP(SHapley Additive exPlanations)and correlation analyses revealed DSCS(the mean ground downward shortwave radiation under clear-sky conditions)to be the most importantly input variable for estimating *** dummy variables(e.g.,longitude,latitude,DEM)were also found to be crucial for model accuracy *** findings indicate the potential for constructing a high-precision and seamless 24-h LST real-time retrieval and monitoring platform for the TP by combining satellite and China's independently developed CLDAS(China Land Data Assimilation System)data in future.

关键词： Tibetan Plateau Himawari-8 ERA5 Land surface temperature Geo-LightGBM

Chord length sampling correction analysis for dispersion fuel in Monte Carlo simulation

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2024年第4期35卷 57-64页

作者： zhao-Yu liang Ding She Yu-Tong Wen Lei Shi Institute of Nuclear and New Energy Technology(INET) Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of EducationTsinghua UniversityBeijing 100084China

Dispersion fuels,knowned for their excellent safety performance,are widely used in advanced reactors,such as hightemperature gas-cooled *** with deterministic methods,the Monte Carlo method has more advantages in the geometric modeling of stochastic *** explicit modeling method has high computational accuracy and high computational *** chord length sampling(CLS)method can improve computational efficiency by sampling the chord length during neutron transport using the matrix chord length?s probability density *** study shows that the excluded-volume effect in realistic stochastic media can introduce certain deviations into the CLS.A chord length correction approach is proposed to obtain the chord length correction factor by developing the Particle code based on equivalent transmission *** numerical analysis against reference solutions from explicit modeling in the RMC code,it was demonstrated that CLS with the proposed correction method provides good accuracy for addressing the excludedvolume effect in realistic infinite stochastic media.

关键词： Stochastic media Monte Carlo Chord length sampling Excluded-volume effect Chord length correction

Machining dynamics and chatters in micro-milling:A critical review on the state-of-the-art and future perspectives

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第7期37卷 59-80页

作者： Qingshun BAI Peng WANG Kai CHENG liang zhao Yabo ZHANG School of Mechanical and Electrical Engineering Harbin Institute of TechnologyHarbin 150001China Department of Mechanical and Aerospace Engineering Brunel University LondonUxbridge UB83PHUK

Micro-milling technology is widely applied in micro manufacturing,particularly for the fabrication of miniature and micro ***,the chatters and machining dynamics related issues in micro-milling are often the main challenges restricting its machining quality and *** research works have rendered that the machining dynamics and chatters in micro-milling are more complex compared with the conventional macro-milling process,likely because of the size effect and rigidity of the micro-milling system including the tooling,workpiece,process variables,materials involved,and the high-speed milling machines,and further their collective dynamic ***,in this paper,the state of the art focusing on micro-milling chatters and dynamics related issues over the past years are comprehensively and critically reviewed to provide some insights for potential researchers and ***,typical applications and the problems caused by the machining dynamics and chatters in micro-milling have been put forward in this ***,the research on the underlying micro-cutting mechanics and dynamics,stability analysis,chatters detection,and chatter suppression are summarized ***,the underlying scientific and technological challenges are discussed particularly against typical precision engineering ***,the possible future directions and trends in research and development of micro-milling have been discussed.

关键词： Micro-milling Machining dynamics Micro-cutting mechanics Stability lobe diagram(SLD) Chatters suppression Digital twin

Tracing the sources of nutrients through the Tsushima/Korea Strait

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2024年第6期43卷 142-152页

作者： Jing Zhang Xinyu Guo Lei Zhu Jianlong Feng liang zhao Key Laboratory of Marine Resource Chemistry and Food Technology Ministry of EducationTianjin 300457China College of Marine and Environmental Science Tianjin University of Science and TechnologyTianjin 300457China Center for Marine Environmental Studies Ehime UniversityMatsuyama 790-8577Japan

The nutrients from the East China Sea(ECS) through the Tsushima/Korea Strait(TS) strongly impact the eco system of the Japan Sea(JS).The complex origins of the Tsushima Warm Current and the various nutrient sources in the ECS result in complex spatial-temporal variations in nutrients in the *** a physical-biological model with a tracking technique,we studied the effects of nutrient sources from the ECS on the *** all the nutrient sources,the Kuroshio has the highest nutrient concentrations in the *** maximum concentration occurs at the bottom,while those of rivers and atmospheric depo sition occur at the surface,and that of the Taiwan Strait occurs in the middle *** nutrient transport through the TS exhibits similar seasonal variations,as does the volume *** transport of nutrients from the Kuroshio accounts for more than 85% of the *** transport of nutrients from the Taiwan Strait is greater during autumn and *** transport of dissolved inorganic nitrogen(DIN) from both rivers and atmospheric deposition through the TS peak in *** transport cannot be equated with volume *** DIN in the less saline zone originates not only from rivers but also from atmospheric deposition and the *** transport of nutrients from the Taiwan Strait is not as significant as its volume transport in the TS.

关键词： dissolved inorganic nitrogen dissolved inorganic phosphate East China Sea Japan Sea nutrient transport

Effect of mesopore spatial distribution of HZSM-5 catalyst on zinc state and product distribution in 1-hexene aromatization

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2024年第3期67卷 16-26页

作者： Chenhao Wei Di Gao Guohao Zhang liang zhao Jinsen Gao Chunming Xu The State Key Lab of Heavy Oil Processing China University of Petroleum(Beijing)Beijing 102249China SINOPEC Research Institute of Petroleum Processing Co. Ltd.Beijing 100083China

1-hexene aromatization is a promising technology to convert excess olefin in fluid catalytic cracking(FCC)gasoline to high-value benzene(B),toluene(T),and ***,the increasing market demand of xylene has put forward higher requirements for new generation of *** increasing xylene yield in 1-hexene aromatization,the effect of mesopore structure and spatial distribution on product distribution and Zn loading was *** with different mesopore spatial distribution were prepared by post-treatment of parent HZSM-5 zeolite,including NaOH treatment,tetra-propylammonium hydroxide(TPAOH)treatment,and *** was found the evenly distributed mesopore mainly prolongs the catalyst lifetime by enhancing diffusion properties but reduces the aromatics selectivity,as a result of damage of micropores close to the catalyst *** the selectivity of high-value xylene can be highly promoted when the mesopore is mainly distributed interior the ***,the state of loaded Zn was also affected by mesopores spatial *** the optimized catalyst,the xylene selectivity was enhanced by 12.4%compared with conventional Zn-loaded parent HZSM-5 catalyst at conversion over 99%.It was attributed to the synergy effect of mesopores spatial distribution and optimized acid *** work reveals the role of mesopores in different spatial positions of 1-hexene aromatization catalysts in the reaction process and the influence on metal distribution,as well as their synergistic effect two on the improvement of xylene selectivity,which can improve our understanding of catalyst pore structure and be helpful for the rational design of high-efficient catalyst.

关键词： 1-Hexene aromatization Alkali treatment Xylene selectivity Mesopores Zinc state

Hypoxia-mediated programmed cell death is involved in the formation of wooden breast in broilers

在线全文

学校读者我要写书评

暂无评论

Journal of Animal Science and Biotechnology 2024年第5期15卷 1918-1931页

作者： Xinrui Zhang Tong Xing Lin Zhang liang zhao Feng Gao College of Animal Science and Technology Key Laboratory of Animal Origin Food Production and Safety Guarantee of Jiangsu ProvinceJiangsu Collaborative Innovation Center of Meat Production and ProcessingQuality and Safety ControlNanjing Agricultural UniversityNo.1 WeigangNanjingJiangsu 210095P.R.China

Background Wooden breast(WB)myopathy is a common myopathy found in commercial broiler chickens *** examination has revealed that WB myopathy is accompanied by damage to the pectoralis major(PM)***,the underlying mechanisms responsible for the formation of WB in broilers have not been fully *** study aimed to investigate the potential role of hypoxia-mediated programmed cell death(PCD)in the formation of WB *** Histological examination and biochemical analysis were performed on the PM muscle of the control(CON)and WB groups.A significantly increased thickness of the breast muscle in the top,middle,and bottom portions(P<0.01)was found along with pathological structure damage of myofibers in the WB *** number of capillaries per fiber in PM muscle,and the levels of p O_(2) and s O_(2) in the blood,were significantly decreased(P<0.01),while the levels of p CO_(2) and TCO_(2) in the blood were significantly increased(P<0.05),suggesting hypoxic conditions in the PM muscle of the WB *** further evaluated the PCD-related pathways including autophagy,apoptosis,and necroptosis to understand the consequence response to enhanced hypoxic conditions in the PM muscle of birds with *** ratio of LC3 II to LC3 I,and the autophagy-related factors HIF-1α,BNIP3,Beclin1,AMPKα,and ULK1 at the m RNA and protein levels,were all significantly upregulated(P<0.05),showing that autophagy occurred in the PM muscle of the WB *** apoptotic index,as well as the expressions of Bax,Cytc,caspase 9,and caspase 3,were significantly increased(P<0.05),whereas Bcl-2 was significantly decreased(P<0.05)in the WB-affected PM muscle,indicating the occurrence of apoptosis mediated by the mitochondrial ***,the expressions of necroptosis-related factors RIP1,RIP3,and MLKL,as well as NF-κB and the pro-inflammatory cytokines TNF-α,IL-1β,and IL-6,were all significantly enhanced(P<0.05)in the WB-affected PM *** T

关键词： Apoptosis Autophagy Broiler chicken Hypoxia Necroptosis Wooden breast

Data-driven Wasserstein distributionally robust chance-constrained optimization for crude oil scheduling under uncertainty

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2024年第5期69卷 152-166页

作者： Xin Dai liang zhao Renchu He Wenli Du Weimin Zhong Zhi Li Feng Qian Key Laboratory of Smart Manufacturing in Energy Chemical Process Ministry of EducationEast China University of Science and TechnologyShanghai 200237China Engineering Research Center of Process System Engineering Ministry of EducationEast China University of Science and TechnologyShanghai 200237China

Crude oil scheduling optimization is an effective method to enhance the economic benefits of oil *** uncertainties,including uncertain demands of crude distillation units(CDUs),might make the production plans made by the traditional deterministic optimization models infeasible.A data-driven Wasserstein distributionally robust chance-constrained(WDRCC)optimization approach is proposed in this paper to deal with demand uncertainty in crude oil ***,a new deterministic crude oil scheduling optimization model is developed as the basis of this *** Wasserstein distance is then used to build ambiguity sets from historical data to describe the possible realizations of probability distributions of uncertain demands.A cross-validation method is advanced to choose suitable radii for these ambiguity *** deterministic model is reformulated as a WDRCC optimization model for crude oil scheduling to guarantee the demand constraints hold with a desired high probability even in the worst situation in ambiguity *** proposed WDRCC model is transferred into an equivalent conditional value-at-risk representation and further derived as a mixed-integer nonlinear programming *** case studies from a real-world refinery are conducted to show the effectiveness of the proposed ***-of-sample tests demonstrate that the solution of the WDRCC model is more robust than those of the deterministic model and the chance-constrained model.

关键词： Distributions Model Optimization Crude oil scheduling Wasserstein distance Distributionally robust chance constraints