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Experimental study of Al agglomeration on solid propellant burning surface and condensed combustion products

Defence Technology（防务技术） 2023年第8期26卷 111-122页

作者： cheng-yin Tu Xiong chen Ying-kun Li Bei-chen Zhang Chang-sheng Zhou School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing210094PR China

Aluminum(Al) particles are commonly added to energetic materials including propellants,explosives and pyrotechnics to increase the overall energy density of the composite,but aluminum agglomeration on the combustion surface may lower the combustion efficiency of propellants,resulting in a loss in twophase ***,it is necessary to understand the agglomeration mechanism of aluminum particles on the combustion *** this paper,a high-pressure sealed combustion chamber is constructed,and high-speed camera is used to capture the whole process of aluminum accumulation,aggregation and agglomeration on the combustion surface,and the secondary agglomeration process near the combustion *** microscopic morphology and chemical composition of the condensed combustion products(CCPs) are then studied by using scanning electron microscopy coupled with energy dispersive(SEM-EDS) *** show that there are three main types of condensed combustion products:small smoke oxide particles oxidized by aluminum vapor,usually less than 1 μm;typical agglomerates formed by the combustion of aluminum agglomerates;carbonized agglomerates that are widely distributed,usually formed by irregular movements of aluminum *** particle size of condensed combustion products is measured by laser particle size *** the pressure increases from 0.5 MPa to 1.0 MPa in nitrogen,the mass average particle size of aluminum agglomerates decreases by 49.7%.As the ambient gas is changed from 0.5 MPa nitrogen to 0.5 MPa air,the mass average particle size of aluminum agglomerates decreases by 67.3%.Results show that as the ambient pressure increases,the higher oxygen content can improve combustion efficiency and reduce the average agglomeration size of aluminum particles.

关键词： Solid propellant Al particles Condensed combustion products Agglomeration Microscopic morphology

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Excellent alkali resistance of Fe,Ce and sulfates co-modified V_(2)O_(5)-WO_(3)/TiO_(2) catalyst for selective catalytic reduction of NO_(x) with NH_(3)

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Journal of Rare Earths 2024年第9期42卷 1682-1692,I0002页

作者： Biyi Huang Xianfang Yi Jianyi Zhang Yuqiu Liu Yanting chen Jinsheng chen Jinxiu Wang Center for Excellence in Regional Atmospheric Environment and Key Lab of Urban Environment and HealthInstitute of Urban EnvironmentChinese Academy of SciencesXiamen361021China College of Resources and Environment Fujian Agriculture and Forestry UniversityFuzhou350002China Fujian Key Laboratory of Atmospheric Ozone Pollution Prevention Institute of Urban EnvironmentChinese Academy of SciencesXiamen361021China University of Chinese Academy of Sciences Beijing100049China

Improving the alkali resistance of catalysts for selective catalytic reduction of NO_(x) with NH_(3) is still a *** this work,the co-modification with Fe,Ce and sulfates on V_(2)O_(5)-WO_(3)/TiO_(2) catalysts(denoted as xSFeCeVWTi) significantly enhances its alkali resistance with K element as a representative.A series of xSFeCeVWTi catalysts was synthesized by wet impregnation with designed 0.05Fe/V, 1.5Ce/V and different S/V molar ratios *** NO_(x) conversion and K resistance of xSFeCeVWTi catalysts increase with the increase of loading amounts of sulfates but no longer further increase as the sulfates load is excessive to block the pores of catalysts and hinder the adsorption of *** optimal modified catalyst in about 2.2S/V actual loading ratio,corresponding to 10.5SFeCeVWTi sample,shows over 99.0%NO_(x) conversion and N_(2) selectivity at 300-400℃ after *** interaction between Fe,Ce and V improves its redox ability but slightly weakens surface acidity,while the proper amount of sulfate species enriches surface Br?nsted acid sites but attenuates its redox ***,a balance of redox capacity and surface acidity,caused by Fe,Ce and sulfate co-modification,contributes to the excellent K resistance of 10.5SFeCeVWTi ***,the change of physicochemical properties influences the reaction mechanism which follows the Eley-Rideal mechanism on *** *** results show that the co-modification with Fe,Ce and sulfates is a good way to improve the alkali tolerance of V_(2)O_(5)-WO_(3)/TiO_(2) catalyst in industrial applications.

关键词： SCR CeO_(2) Fe_(2)O_(3) SO_(4)^(2-) K resistance K poisoning

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Distribution of diatoms in the water and surface sediments of southern South China Sea

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Chinese Science Bulletin 2006年第B12期51卷 76-80页

作者： LU Jun chen Muhong chen Zhong CAS Key Laboratory of Marginal Sea Geology South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou 510301 China

The relationship of species and abundance between the diatoms in the water and sediments from the southern South China Sea (SCS)were discussed, and the key environmental controlling factors were also investigated. Studies show thathe diatom abundance is high in both water andsediments in the southeast part of the southern SCSand the varying trend is similar, while in the northwespart, the abundance is low, and the varying trend isdifferent. The dominant diatom species are Thalassionema nitzschioides and Nitzschia bicapitata inwater, and T. nitzschioides and Chaetoceros messanensis in sediments. The diatom species of smalsize and thin shell in water are more than in thesediments, while the diatom species of large size andthick shell in water are less. The percentage of species T. nitzschioides is higher in water of southeaspart than in that of northwest part, but it is similar insediments of both areas. It is shown that the southwest monsoon is the important factor influencingdiatom abundance and T. nitzschioides percentageand when the southwest monsoon is well developedthe distribution of diatom abundance and T. nitzschioides percentage are consistent in both water andsediments of the study area.

关键词：南海南部海域硅藻属水体沉积物分布东南季风

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SUPERCONVERGENCE OF GRADIENT RECOVERY SCHEMES ON GRADED MESHES FOR CORNER SINGULARITIES

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Journal of Computational Mathematics 2010年第1期28卷 11-31页

作者： Long chen Hengguang Li Department of Mathematics University of California at Irvine Irvine CA 92697 USA Department of Mathematics Syracuse University Syracuse NY 13244 USA

For the linear finite element solution to the Poisson equation, we show that supercon- vergence exists for a type of graded meshes for corner singularities in polygonal domains. In particular, we prove that the L^2-projection from the piecewise constant field △↓UN to the continuous and piecewise linear finite element space gives a better approximation of △↓U in the Hi-norm. In contrast to the existing superconvergence results, we do not assume high regularity of the exact solution.

关键词： Superconvergence Graded meshes Weighted Sobolev spaces Singular solutions The finite element method Gradient recovery schemes.

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Fixed Point Theorems for φ-Probabilistic Contraction in Hausdorff Fuzzy Metric Spaces

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Wuhan University Journal of Natural Sciences 2021年第3期26卷 243-248页

作者： chen He School of Mathematics and Statistics Wuhan UniversityWuhan 430072HubeiChina

In this paper,we discuss the common fixed point with respect to several self-mappings on fuzzy metric *** many authors put forward some relevant common fixed point theorems,and their theorems require that these mappings have some assumptions such as commutativity or ***,our results do not need these assumptions but only these mappings areφ-probabilistic *** defining a new mapping on the space which formed by compact sets,we can obtain these mappings’common fixed ***,we give some examples to justify our results.

关键词： fuzzy metric space φ-probabilistic contraction Hausdorff fuzzy metric common fixed point

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Effect of Al_(2)O_(3)/SiO_(2) ratio on morphology of complex calcium ferrite

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Journal of Iron and Steel Research International 2023年第10期30卷 1921-1928页

作者： Dai-wei Yang Wei Wang Jing-xuan Li Xu-heng chen Peng-fei chen Jiangsu Yonggang Group Co. Ltd.IronworksSuzhou 215600JiangsuChina Hubei Provincial Engineering Technology Research Center of Metallurgical Secondary Resources Wuhan University of Science and TechnologyWuhan 430081HubeiChina Beijing Zhiye Interconnection Technology Co. Ltd.Beijing 100144China

Al_(2)O_(3) and SiO_(2) greatly influence the formation of complex calcium ferrite,which is the main bonding phase in high basicity *** effects of Al_(2)O_(3)/SiO_(2) ratios on the morphology of complex calcium ferrite were *** main mineral phases in the samples with different Al_(2)O_(3)/SiO_(2) ratios were CaFe_(2)O_(4) with a solid solution of Si or Al atoms and the silico-ferrite of calcium and *** results showed that the morphology of the complex calcium ferrite changed from lumpy to plate-like and acicular with increases in the SiO_(2) content and the Al_(2)O_(3)/SiO_(2) *** the content of SiO_(2) was 4 wt.%,the main calcium ferrite morphology was acicular,and the number of macropores in the samples increased with the Al_(2)O_(3)/SiO_(2) ratio *** first-principles analysis of the calcium ferrite crystal structure showed that adding SiO_(2) and Al_(2)O_(3) changed the growth mechanism of the CaFe_(2)O_(4) crystal,promoting the formation of platy and acicular complex calcium *** size of calcium ferrite was significantly smaller due to the increase in CaO-Fe_(2)O_(3)-SiO_(2)-Al_(2)O_(3) viscosity with increasing the Al_(2)O_(3)/SiO_(2) ratio.

关键词： Complex calcium ferrite Silico-ferrite of calcium and aluminum Al_(2)O_(3)/SiO_(2)ratio Morphology First-principles calculation

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Effect of Graphite Content and Granularity on Mechanical and Tribological Properties of Bronze Alloyed Powder Composite

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Journal of Iron and Steel Research International 2005年第1期12卷 54-57页

作者： DENG chen-hong chen Guang-zhi GE Qi-lu Central Iron and Steel Research Institute

The bronze alloyed powder composite containing nanoparticles was developed by hot *** effects of the content and granularity of graphite on hardness,machinability,bending strength,compression strength,and friction and wear behavior of the composites were *** microstructures of the specimens were analyzed by *** results showed that the graphites are distributed in net when nanographites are added,resulting in the decrease of mechanical properties and abrasive *** the content of nanographite is 10%,the composite is *** graphite is distributed in the form of block when micrographite is added,improving the mechanical properties and abrasive *** track was studied by SEM.

关键词： nanoparticle mechanical property friction wear abrasive resistance

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Effect of sorbed and desorbed Zn(Ⅱ) on the growth of a green alga (Chlorella pyrenoidosa)

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Journal of Environmental Sciences 2007年第9期19卷 1028-1031页

作者： CHANG Guo-hua chen Hao chen Hai-liu LI Wei PAN Gang State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China

Toxic effect of Zn（II） on a green alga （Chlorella pyrenoidosa） in the presence of sepiolite and kaolinite was investigated. The Zn-free clays were found to have a negative impact on the growth of C. pyrenoidosa in comparison with control samples （without adding any clay or Zn（II））. When Zn（II） was added, the algae in the presence of clays could be better survived than the control samples, which was actually caused by a decrease in Zn（II） concentration in the solution owing to the adsorption of Zn（II） on the clays. When the solution system was diluted, the growth of algae could be further inhibited as compared to that in a system which had the same initial Zn（II） concentration as in the diluted system. This in fact resulted from desorption of Zn（II） from the zinc-contaminated clays, although the effect varied according to the different desorption capabilities of sepiolite and kaolinite. Therefore the adsorption and desorption processes of Zn（H） played an important part in its toxicity, and adsorption and desorption of pollutants on soils/sediments should be well considered in natural eco-environmental systems before their risk of toxicity to aquatic organisms was assessed objectively.

关键词： Chlorella pyrenoidosa clays adsorption and desorption toxicity

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Hydriding-dehydriding properties of Mg_2Ni alloy modified by ball-milling in tetrahydrofuran

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Rare Metals 2004年第2期23卷 138-142页

作者： chen Changpin WANG Wei chen Yun chen Lixin WANG Qidong Department of Materials Science and Engineering, Zhejiang University Hangzhou 310027, China Department of Materials Science and Engineering Zhejiang University Hangzhou 310027

A new approach of ball-milled Mg_2Ni in tetrahydrofuran (THF) to improve thehydriding kinetics of Mg_2Ni alloy is suggested and studied. It is found that the modified alloydisplayed the improved activity for hydriding even at relatively low temperature (e.g., 323-373 K).In the case of the sample milled in THF for 20 h, the hydrogen content (mass fraction) reaches 1.6 %at 323 K, 2.1% at 348 K and 3.4% at 448 K, respectively. The use of THF during grinding led to thechange of the structure, which is reflected by the broadening and weakening of the diffraction peaksin the XRD spectra. The XPS analysis shows that Mg (2s) binding energy peak of Mg_2Ni aftermodification shifted from a lower binding energy to a higher one, indicating the charge transferencebetween Mg and THF and the formation of catalytically active electron donor-acceptor (EDA)complexes on the surface of modified Mg_2Ni alloy.

关键词： metal materials Mg_2Ni alloy ball-milling tetrahydrofuran hydriding-dehydriding property

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Linguistic Knowledge Representation in DPoS Consensus Scheme for Blockchain

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Computers, Materials & Continua 2023年第10期77卷 845-866页

作者： Yixia chen Mingwei Lin College of Computer and Cyber Security Fujian Normal UniversityFuzhou350117China Fujian Provincial Engineering Research Center for Public Service Big Data Mining and Application Fujian Normal UniversityFuzhou350117China

The consensus scheme is an essential component in the real blockchain *** Delegated Proof of Stake(DPoS)is a competitive consensus scheme that can decrease energy costs,promote decentralization,and increase efficiency,***,how to study the knowledge representation of the collective voting information and then select delegates is a new open *** ensure the fairness and effectiveness of transactions in the blockchain,in this paper,we propose a novel fine-grained knowledge representation method,which improves the DPoS scheme based on the linguistic term set(LTS)and proportional hesitant fuzzy linguistic term set(PHFLTS).To this end,the symmetrical LTS is used in this study to express the fine-grained voting options that can be chosen to evaluate the blockchain *** is used to model the collective voting information on the voted blockchain nodes by aggregating the voting information from other blockchain *** rank the blockchain nodes and then choose the delegate,a novel delegate selection algorithm is proposed based on the cumulative possibility ***,the numerical examples are used to demonstrate the implementation process of the proposed DPoS consensus algorithm and also its ***,the superiority of the proposed DPoS consensus algorithm is *** results show that the proposed DPoS consensus algorithm shows better performance than the existing DPoS consensus algorithms.

关键词： Linguistic term set MCDM aggregation operator

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