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Modification of methyl oleate for silicon-based biological lubricating base oil

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Chinese Journal of Chemical Engineering 2017年第1期25卷 130-136页

作者： Shixing cui Zhi Yun xia Gui College of Chemistry and Chemical Engineering Nanjing University of Technology Nanjing 210009 China

A new kind of silicon-based biological lubricating base oil with good viscosity-temperature behavior,viscosity index,thermostability,oxidation stability and wear resistance performance was synthesized as a derivative of methyl *** reaction was introduced to further improve methyl oleate oxidation stability and lubricity after epoxidation and open-ring *** order of effectiveness of acid binding agent was N,N-diisopropylethylamine(DIEA) > pyridine > diethylamine > triethylamine,and the effects of various parameters on the trimethylsilylation reaction as well as on the silicon-oxygen bond stability and reaction yield were studied.A maximum yield of 34.54%was achieved at hydroxyl/trimethyl chlorosilane/DIEA molar ratio of1:1.25:1,reaction temperature 40℃,reaction time 1.5 h.

关键词： Methyl oleate Trimethyl chlorosilane Acid binding agent N N-diisopropylethylamine Lubricity Silicon-based biological lubricating base oil

Performance of hybrid constructed wetland systems for treating septic tank effluent

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Journal of Environmental Sciences 2006年第4期18卷 665-669页

作者： cui Li-hua LIU Wen ZHUXi-zhen ma Mei HUANG Xi-hua xia Yan-yang Department of Environmental Science and Engineering South China Agricultural University Guangzhou 510642 China Coast to Coast Analytical Specialists Garland TX 75081 USA

The integrated wetland systems were constructed by combining horizontal-flow and vertical-flow bed, and their purification efficiencies for septic tank effluent were detected when the hydraulic retention time （HRT） was 1 d, 3 d, 5 d under different seasons. The results showed that the removal efficiencies of the organics, phosphorus were steady in the hybrid systems, but the removal efficiency of total nitrogen was not steady due to high total nitrogen concentration in the septic tank effluent. The average removal rates of COD （chemical oxygen demand） were 89%, 87%, 83%, and 86% in summer, autumn, winter and spring, respectively, and it was up to 88%, 85%, 73%, and 74% for BOD5 （5 d biochemical oxygen demand） removal rate in four seasons. The average removal rates of TP （total phosphorous） could reach up to 97%, 98%, 95%, 98% in four seasons, but the removal rate of TN （total nitrogen） was very low. The results of this study also indicated that the capability of purification was the worst in winter. Cultivating with plants could improve the treated effluent quality fTom the hybrid systems. The results of the operation of the horizontal-flow and vertical-flow cells （hybrid systems） showed that the removal efficiencies of the organics, TP and TN in horizontal-flow and vertical-flow cells were improved significantly with the extension of HRT under the same season. The removal rate of 3 d HRT was obviously higher than that of 1 d HRT, and the removal rate of 5 d HRT was better than that of 3 d HRT, but the removal efficiency was not very obvious with the increment of HRT. Therefore, 3 d HRT might be recommended in the actual operation of the hybrid systems for economic and technical reasons.

关键词： constructed wetlands hybrid system horizontal-flow vertical-flow removal efficiency septic tank effluent

A Method of Estimating Computational Complexity Based on Input Conditions for N-vehicle Problem

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Acta mathematicae Applicatae Sinica 2010年第1期26卷 1-12页

作者： Xi xia Jin-chuan cui Academy of mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China

This paper proposes a method of estimating computational complexity of problem through analyzing its input condition for N-vehicle exploration problem. The N-vehicle problem is firstly formulated to determine the optimal replacement in the set of permutations of 1 to N. The complexity of the problem is factorial of N （input scale of problem）. To balance accuracy and efficiency of general algorithms, this paper mentions a new systematic algorithm design and discusses correspondence between complexity of problem and its input condition, other than just putting forward a uniform approximation algorithm as usual. This is a new technique for analyzing computation of NP problems. The method of corresponding is then presented. We finally carry out a simulation to verify the advantages of the method： 1） to decrease computation in enumeration; 2） to efficiently obtain computational complexity for any N-vehicle case; 3） to guide an algorithm design for any N-vehicle case according to its complexity estimated by the method.

关键词： Complexity of computation combinatorial optimization N-vehicle problem permutations inverse order

Fuzzy data envelopment analysis approach based on sample decision making units

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Journal of Systems Engineering and Electronics 2012年第3期23卷 399-407页

作者： Muren Zhanxin ma Wei cui School of mathematical Sciences Inner Mongolia University Hohhot 010021 E R. China Department of mathematics Inner Mongolia University of Technology Hohhot 010051 E R. China School of Economics and management Inner Mongolia University Hohhot 010021 P. R. China

The conventional data envelopment analysis （DEA） measures the relative efficiencies of a set of decision making units with exact values of inputs and outputs. In real-world prob- lems, however, inputs and outputs typically have some levels of fuzziness. To analyze a decision making unit （DMU） with fuzzy input/output data, previous studies provided the fuzzy DEA model and proposed an associated evaluating approach. Nonetheless, numerous deficiencies must still be improved, including the α- cut approaches, types of fuzzy numbers, and ranking techniques. Moreover, a fuzzy sample DMU still cannot be evaluated for the Fuzzy DEA model. Therefore, this paper proposes a fuzzy DEA model based on sample decision making unit （FSDEA）. Five eval- uation approaches and the related algorithm and ranking methods are provided to test the fuzzy sample DMU of the FSDEA model. A numerical experiment is used to demonstrate and compare the results with those obtained using alternative approaches.

关键词： fuzzy mathematical programming sample decision making unit fuzzy data envelopment analysis efficiency α-cut.

ANALYSIS ON A NUMERICAL SCHEME WITH SECOND-ORDER TIME ACCURACY FOR NONLINEAR DIFFUSION EQUATIONS

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Journal of Computational mathematics 2021年第5期39卷 777-800页

作者： xia cui Guangwei Yuan Fei Zhao Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsP.O.Box 8009-26Beijing 100088China College of Science North China University of TechnologyBeijing 1OO144China Graduate School of China Academy of Engineering Physics Beijing 100088China

A nonlinear fully implicit finite difference scheme with second-order time evolution for nonlinear diffusion problem is *** scheme is constructed with two-layer coupled discretization(TLCD)at each time *** does not stir numerical oscillation,while permits large time step length,and produces more accurate numerical solutions than the other two well-known second-order time evolution nonlinear schemes,the Crank-Nicolson(CN)scheme and the backward difference formula second-order(BDF2)*** developing a new reasoning technique,we overcome the difficulties caused by the coupled nonlinear discrete diffusion operators at different time layers,and prove rigorously the TLCD scheme is uniquely solvable,unconditionally stable,and has second-order convergence in both s-pace and *** tests verify the theoretical results,and illustrate its superiority over the CN and BDF2 schemes.

关键词： Nonlinear diffusion problem Nonlinear two-layer coupled discrete scheme Second-order time accuracy Property analysis Unique existence Convergence

Nil-Clean Rings with Involution

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Algebra Colloquium 2021年第3期28卷 367-378页

作者： Jian cui Guoli xia Yiqiang Zhou Department of mathematics Anhui Normal UniversityWuhuAnhui 241002China Department of mathematics and Statistics Memorial University of Newfoundland St.John’sNL A1C 5S7Canada

A*-ring R is called a nil *-clean ring if every element of R is a sum of a projection and a ****-clean rings are the version of nil-clean rings introduced by *** paper is about the nil*-clean property of rings with emphasis on matrix *** show that a*-ring R is nil*-clean if and only if J(R)is nil and R/J(R)is nil*-*** a 2-primal*-ring R,with the induced involution given by(aij)*=(a*ij)^(T),the nil*-clean property of Mn(R)is completely reduced to that of Mn(Zn).Consequently,Mn(R)is not a nil*-clean ring for n=3,4,and M2(R)is a nil*-clean ring if and only if J(R)is nil,R/J(R)is a Boolean ring and a*-a∈J(R)for all a∈R.

关键词： idempotent nilpotent projection nil-clean ring *-ring nil*-clean ring matrix ring

Robust Nonparametric Function Estimation for Errors-in-variables Models

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Acta mathematicae Applicatae Sinica 2020年第2期36卷 314-331页

作者： Chao-xia YUAN Heng-jian cui School of mathematical Sciences Capital Normal UniversityBeijing 100048China

This paper discusses robust nonparametric estimators of location regression function for errorsin-variables model with de-convolution *** local constant smoother is used for the estimation of the nonparametric function,and the local linear smoother is proposed to deal with the boundary problem,as well as to improve the local constant *** establish the asymptotic properties of the estimator,the influence function of the statistical functional and the breakdown point.A simulation study is carried out to demonstrate robust performance of the proposed *** motorcycle data is presented to illustrate the application of the robust estimator further.

关键词： errors-in-variables de-convolution kernel robust local linear

Optimization Design of the Grate Cooler Based on the Power Flow Method and Genetic Algorithms

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Journal of Thermal Science 2020年第6期29卷 1617-1626页

作者： ma xiaoteng CAO Qun cui Zheng Institute of Thermal Science and Technology Shandong UniversityJi'an 250061China

As an important process during the cement production,grate cooler plays significance roles on clinker cooling and waste heat *** this paper,we measured experimentally the heat balance of the grate cooler,which provided initial operating parameters for ***,the grate cooler was simplified into a series-connected heat exchanger network by power flow *** the equivalent thermal resistance network provided the global constraints by Kirchhoff’s *** this basis,with the objectives of the minimum entropy generation numbers caused by heat transfer and viscous dissipation,solving a multi-objective optimization model achieved the Pareto Front by genetic *** selecting the scheme of the lowest fan power consumption obtained the optimal operating parameters of the grate *** results showed that the total mass flow of the optimized scheme did not change significantly compared with the original scheme,but the fan power consumption was 25.44%lower,and the heat recovery efficiency was 88.43%,which was improved by 11.35%.Furthermore,the analysis showed that the optimal operating parameters were affected by the local heat *** optimizing the diameter of clinker particles within the allowable industrial range,the clinker with particle diameter of 0.02 m had the optimal performance.

关键词： power flow method genetic algorithm grate cooler entropy generation minimization multi-objective optimization

A H_(2)O-in-zircon perspective on the heterogeneous water content of crust-derived magmas in southern Tibet

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Science China Earth Sciences 2021年第7期64卷 1184-1194页

作者： Juntong MENG xiaoping xia Lin ma Ziqi JIANG Jian XU Zexian cui Qing YANG Wanfeng ZHANG Le ZHANG State Key Laboratory of Isotope Geochemistry Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China CAS Center for Excellence in Deep Earth Science Guangzhou 510640China College of Earth and Planetary Science University of Chinese Academy of SciencesBeijing 100049China School of Earth Science Guilin University of TechnologyGuilin 541004China

Geophysical and geochemical evidence revealed that certain amounts of water are stored in the Earth’s interior,and its distribution exhibits temporal and spatial *** studies indicate that the H_(2)O-in-zircon has a potential to reveal magma water *** secondary ion mass spectrometry(SIMS),we analyzed the zircon water content and oxygen isotopes in granitoids(two-mica granite,quartz monzonite,diorite,and granodiorite)from southern *** results are used to explore the diversity of water content in crust-derived magmas,which is also supported by the LA-ICPMS zircon trace element *** are low zircon water contents for two partial melting products of the ancient crust(peak at 85 and300 ppm,respectively).Meanwhile,there are high H_(2)O-in-zircon peaks(435 and 475 ppm,respectively)for two partial melting products of the juvenile *** calculated radiation damage accumulation in these zircon grains is below 3×10^(15)αdecay events mg^(–1),suggesting that the zircon grains are well *** is no correlation between REE+Y and H+P,indicating that the mechanism of charge balance for water uptaking into zircon,in which the excess of REE+Y to P controls Hcontent,is not applicable to the studied *** degree of magma fractionation cannot account for the zircon water content variation,because there is no co-variation between zircon Hf and H_(2)O ***,the degree of partial melting was unlikely to be responsible for the H_(2)O-in-zircon *** interpret that the H_(2)O-in-zircon variation reflects the influence of melting mode(dehydration ***-fluxed)and water content in the crustal *** the Late Devonian,dehydration melting of the crustal rocks was facilitated at elevated temperatures,which produced magmas with the lowest water ***-fluxed melting of the ancient crust would produce relatively“drier”magma than water-fluxed melting of the juvenile crust.

关键词： H_2O-in-zircon SIMS dehydration melting water-fluxed melting magma water content