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Large eddy simulation of turbulent premixed and stratified combustion using flame surface density model coupled with tabulation method

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Applied Mathematics and Mechanics(English Edition) 2018年第12期39卷 1719-1736页

作者： zhou YU Hongda ZHANG Taohong ye Minming ZHU Department of Thermal Science and Energy Engineering University of Science and Technology of China Shenyang Engine Research Institute Aero Engine (Group) Corporation of China

Large eddy simulations(LESs) are performed to investigate the Cambridge premixed and stratified flames, SwB1 and SwB5, respectively. The flame surface density(FSD) model incorporated with two different wrinkling factor models, i.e., the Muppala and Charlette2 wrinkling factor models, is used to describe combustion/turbulence interaction, and the flamelet generated manifolds(FGM) method is employed to determine major scalars. This coupled sub-grid scale(SGS) combustion model is named as the FSD-FGM model. The FGM method can provide the detailed species in the flame which cannot be obtained from the origin FSD model. The LES results show that the FSD-FGM model has the ability of describing flame propagation, especially for stratified flames. The Charlette2 wrinkling factor model performs better than the Muppala wrinkling factor model in predicting the flame surface area change by the *** combustion characteristics are analyzed in detail by the flame index and probability distributions of the equivalence ratio and the orientation angle, which confirms that for the investigated stratified flame, the dominant combustion modes in the upstream and downstream regions are the premixed mode and the back-supported mode, respectively.

关键词： large eddy simulation(LES) flame surface density(FSD) model tabulation premixed combustion stratified combustion

Synthesis and characterization of PMMA/Al_2O_3 composite particles by in situ emulsion polymerization

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Particuology 2008年第3期6卷 207-213页

作者： Hui Liu Hongqi ye Tianquan Lin Tao zhou College of Chemistry and Chemical Engineering Central South University Changsha 410083 China

In order to improve its dispersibility, superfine alumina （A1203） was encapsulated with poly（methyl methacrylate）（PMMA） by in situ emulsion polymerization. It was found that only when the concentration of sodium dodecyl sulfate （SDS） was much higher than its critical micelle concentration, could PMMA/Al2O3 composite particles with high percentage of grafting （PG） be prepared. The same results were obtained between the experimental and stoichiometric amounts of tris（dodecylbenzenesulfonate） isopropoxide （NDZ）, indicating that single-molecule-layer adsorption had taken place between NDZ and Al2O3. Analysis using FTIR, TEM and XPS showed that PMMA/Al2O3 composite particles with core-shell structure had been successfully synthesized by in situ emulsion polymerization. Compared to Al2O3, thermal stability and dispersibility of the composite particles showed marked improvement.

关键词： PMMA Alumina Composite particle Encapsulation Dispersibility

Design and preparation of gradient graphite/cermets self-lubricating composites

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Journal of Materials Science & Technology 2018年第8期34卷 1378-1386页

作者： Liming zhou Ji Xiong Zhixing Guo Junliu ye School of Manufacturing Science and Engineering Sichuan University

Based on the functionally graded materials （FGMs） design concept, the laminated-graded graphite/cermets self-lubricating composite was prepared to achieve the integration of mechanical prop- erties and lubrication performance of the cermet. The effects of the layer number and thickness of graded structure on residual stresses in the gradient composites were investigated by finite element method （FEM）. From the FEM analyses, the optimal gradient structure design was obtained correspond- ing to the following parameters： the number of graded layers n = 2 and the thickness of graded structure t = I ram. According to the optimum design, a graded graphite/cermets self-lubricating material with two layers was fabricated by a typical powder metallurgy technique. Compared with the homogenous graphite/cermets composite, the surface hardness and indentation fracture toughness of graded compos- ite were increased by approximately 15.9% and 6.3%, respectively. The results of X-ray diffraction （XRD） stress measurement identified the existence of residual compressive stress on the surface of graded com- posite. Additionally, the friction and wear tests revealed that the wear resistance of the graphite/cermets self-lubricating composite was improved significantly via the graded structural design, whereas the coefficient of friction changed slightly.

关键词： Graphite/cermets self-lubricating material Graded structure Finite element analysis Mechanical properties Tribological performance

Effects of Rare Earth,Titanium,and Magnesium Additions on Microstructures and Properties of High-boron Medium-carbon Alloy

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Journal of Iron and Steel Research International 2016年第11期23卷 1226-1233页

作者： Xiao-li SHI ye-hua JIANG Rong zhou Faculty of Materials Science and Engineering Kunming University of Science and Technology

In order to improve the toughness and wear resistance of high-boron medium-carbon alloy （HBMCA）, a novel wear-resistant HBMCA comprising granular borocarbide was obtained by titanium, magnesium, and rare earth modifications. These modifications gave rise to greatly refined as-cast eutectic borocarbide structures and a less interconnected continuous borocarbide network. Heat treatment mostly produced broken and spheriodized borocarbides that tended to exist as isolated particles in modified HBMCA. The heat treated modified HBMCA exhibited enhanced hardness than pristine and impact toughness was improved significantly to 12.5 J/cm^2. In addition, it displayed 2.39 and 1.7 times greater wear resistance than high-speed steel （HSS） and high nickel-chromium alloy steel （Cr25） at high temperature （500℃）, respectively. Here, the modification mechanisms involving Re2O3, TiN, and MgO/ MgS heterogeneous nuclei were discussed.

关键词： modification eutectic borocarbide spheroidization toughness wear resistance

Pseudospectral method for optimal propellantless rendezvous using geomagnetic Lorentz force

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Applied Mathematics and Mechanics(English Edition) 2015年第5期36卷 609-618页

作者： Xu HUANG ye YAN Yang zhou Hua ZHANG College of Aerospace Science and Engineering National University of Defense Technology Department of Communication Beijing Aerospace Control Center

A charged spacecraft is subject to the Lorentz force when it orbits a central body with a magnetic field. The induced Lorentz force provides a new mean of propellantless electromagnetic propulsion for orbital control. Modeling the Earth magnetic field as a tilted dipole that co-rotates with the Earth, this paper develops a nonlinear dynamical model that describes the relative motion of the Lorentz spacecraft about an arbitrary reference orbit. Based on the proposed dynamical model, feasibility of Lorentz-propelled rendezvous with no restrictions on the initial states is investigated. The rendezvous problem is then formulated as an optimal control problem, and solved with the Gauss pseudospectral method（GPM）. Numerical simulations substantiate the validity of proposed model and method, and results show that the propellantless rendezvous is achieved at both fixed and free final time.

关键词： Lorentz dynamical dipole spacecraft propulsion validity orbital integer formulated constraints

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

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 analysis 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 dynamic 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 dynamic model indicate that it can preserve the premixed flame propagation characteristics better.

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

Extracellular CIRP dysregulates macrophage bacterial phagocytosis in sepsis

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Cellular & Molecular Immunology 2023年第1期20卷 80-93页

作者： mian zhou Monowar Aziz Hao-Ting yen Gaifeng Ma Atsushi Murao Ping Wang Center for Immunology and Inflammation The Feinstein Institutes for Medical ResearchManhassetNYUSA Departments of Surgery and Molecular Medicine Zucker School of Medicine at Hofstra/NorthwellManhassetNYUSA

In sepsis, macrophage bacterial phagocytosis is impaired, but the mechanism is not well elucidated. Extracellular cold-inducible RNA-binding protein (eCIRP) is a damage-associated molecular pattern that causes inflammation. However, whether eCIRP regulates macrophage bacterial phagocytosis is unknown. Here, we reported that the bacterial loads in the blood and peritoneal fluid were decreased in CIRP^(−/−) mice and anti-eCIRP Ab-treated mice after sepsis. Increased eCIRP levels were correlated with decreased bacterial clearance in septic mice. CIRP−/− mice showed a marked increase in survival after sepsis. Recombinant murine CIRP (rmCIRP) significantly decreased the phagocytosis of bacteria by macrophages in vivo and in vitro. rmCIRP decreased the protein expression of actin-binding proteins, ARP2, and p-cofilin in macrophages. rmCIRP significantly downregulated the protein expression of βPIX, a Rac1 activator. We further demonstrated that STAT3 and βPIX formed a complex following rmCIRP treatment, preventing βPIX from activating Rac1. We also found that eCIRP-induced STAT3 phosphorylation was required for eCIRP’s action in actin remodeling. Inhibition of STAT3 phosphorylation prevented the formation of the STAT3-βPIX complex, restoring ARP2 and p-cofilin expression and membrane protrusion in rmCIRP-treated macrophages. The STAT3 inhibitor stattic rescued the macrophage phagocytic dysfunction induced by rmCIRP. Thus, we identified a novel mechanism of macrophage phagocytic dysfunction caused by eCIRP, which provides a new therapeutic target to ameliorate sepsis.

关键词： βPIX eCIRP Macrophage Phagocytosis Rac1 STAT3

Noble gas isotopic compositions of deep carbonate rocks from the Tarim Basin

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Chinese Science Bulletin 2002年第9期47卷 774-778页

作者： zhou, SX ye, XR Chinese Acad Sci Lanzhou Inst Geol State Key Lab Gas Geochem Lanzhou 730000 Peoples R China

Abundances and isotopic compositions of noble gases (He, Ne, Ar, Kr) with various existence states in carbonate rocks from the Tacanl Well have been investigated by means of the stepwise heating technique. The elemental abundance patterns of noble gases in the samples show the enrichment of heavy noble gases and depletion of 20Ne relative to the atmosphere, which are designated as type-I and are similar to that observed in water, natural gases and sedimentary rocks. The 3He/4He ratios of deep carbonate samples at lower and medium temperature (300-700°C) and a majority of samples at higher temperature (1100-1500°C) steps are very similar to those of natural gases in the same strata in this area, this feature of radiogenic crustal helium shows that the Tazhong Uplift is relatively stable. However, significant helium and argon isotopic anomalies are found at the 1100°C step in the Middle-Upper Ordovi-cian carbonate rock, suggesting the incorporation of mantle-derived volatiles, this may be due to minor

关键词： Tarim Basin Tacanl Well carbonate rocks noble gases.

Disturbed bone remodelling activity varies in different stages of experimental, gradually progressive apical periodontitis in rats

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International Journal of Oral Science 2019年第4期11卷 289-299页

作者： Ruoshi Xu Daimo Guo Xuedong zhou Jianxun Sun Yachuan zhou Yi Fan Xin zhou mian Wan Wei Du Liwei Zheng State Key Laboratory of Oral Diseases National Clinical Research Center for Oral DiseasesDepartment of Cariology and EndodontologyWest China Hospital of StomatologySichuan UniversityChengduChina State Key Laboratory of Oral Diseases National Clinical Research Center for Oral DiseasesDepartment of PediatricsWest China Hospital of StomatologySichuan UniversityChengduChina

Bone remodelling keeps going through the lifespan of human by bone formation and bone *** the craniofacial region,mandibles act as the main force for biting and chewing,and also become susceptible to a common bone-loss disease,namely,apical periodontitis,once infected dental pulp is not treated timely,during which bone resorption occurs from the apical foramen to the apical bone *** conventional root canal treatment(RCT)can remove the most of the infection,chronical apical periodontitis due to incomplete removal of dental pulp and subsequent microleakage will become refractory and more challenging,and this process has scarcely been specifically studied as a bone remodelling issue in rat ***,to study chronical and refractory apical periodontitis owing to incomplete cleaning of infected dental pulp and microleackage in vivo,we establish a modified rat model of gradually progressive apical periodontitis by sealing residual necrotic dental pulp and introducing limited saliva,which simulates gradually progressive apical periodontitis,as observed in the clinical treatment of chronical and refractory apical *** show that bone-loss is inevitable and progressive in this case of apical periodontitis,which confirms again that complete and sound root canal treatment is crucial to halt the progression of chronical and refractory apical periodontitis and promote bone ***,bone remodelling was enhanced at the initial stage of apical periodontitis in this model while reduced with a high osteoblast number afterwards,as shown by the time course study of the modified *** that the pathological apical microenvironment reserve its hard tissue formation ability to some degree but in a disturbed ***,our findings can provide insights for future bone regenerative treatment for apical periodontitisassociated bone loss.

关键词： incomplete modelling progressive