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Journal of Computational Mathematics 2006年第1期24卷 9-18页

作者： Jin Huang tao lu University of electronic & science technology of China Chengdu 610055 Mathematical College Sichuan University Chengdu 610065 China

Taking hm as the mesh width of a curved edge Гm （m = 1, ..., d ） of polygons and using quadrature rules for weakly singular integrals, this paper presents mechanical quadrature methods for solving BIES of the first kind of plane elasticity Dirichlet problems on curved polygons, which possess high accuracy O（h0^3） and low computing complexities. Since multivariate asymptotic expansions of approximate errors with power hi^3 （i = 1, 2, ..., d） are shown, by means of the splitting extrapolations high precision approximations and a posteriori estimate are obtained.

关键词： Splitting extrapolation Linear elasticity Dirichlet problem Boundary integral equation of the first kind Mechanical quadrature method

Numerical Simulation of Three-dimensional Heat and Mass Transfer in Spray Cooling of Converter Gas in a Venturi Scrubber

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Chinese Journal of Mechanical Engineering 2009年第5期22卷 745-754页

作者： lu tao WANG Kuisheng School of Mechanical and Electrical Engineering Beijing University of Chemical Technology Beijing 100029 China

In order to predict the pressure drop, collection efficiency, velocity, temperature and mole fraction of vapor in an industrial venturi scrubber with water spraying for converter gas cooling, a three-dimensional model of heat and mass transfer with phase change is established. The gas flow and liquid droplets are treated as a continuous phase with a Eulerian approach and as a discrete phase with a Lagrangian approach, respectively. The coupled problem of heat, force, and mass transfers between gas flow and liquid droplets is solved by a commercial computational fluid dynamics（CFD） package, FluENT. The numerical results show that the water injections have an important influence on the distributions of pressure, velocity, temperature, and mole fraction of vapor, especially for the spraying region in the throat. In the spraying region, the pressure drop is higher and the velocity is lower than in other regions due to the gas-droplet drag, while the temperature is lower because the droplet absorbs large amounts of heat from the high temperature gas and the mole fraction of vapor is higher due to the phase change of the liquid droplet. A number of cases with different Water-to-gas volume flow ratios and baffle openings were simulated. The dependence of pressure drop, velocity, temperature, mole fraction of vapor, and collection efficiency on both the water-to-gas volume flow ratio and baffle opening are analyzed. The good agreements between simulation results and experiment data of pressure drop, temperature, and collection efficiency validate the model. The model should facilitate optimization of the venturi scrubber design in order to give better performance with lower pressure drops and higher collection efficiency.

关键词： numerical simulation heat and mass transfer spray cooling converter gas venturi scrubber

APPROXIMATIONS OF HYPERSINGULAR INTEGRALS FOR NEGATIVE FRACTIONAL EXPONENT

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Journal of Computational Mathematics 2018年第5期36卷 627-643页

作者： Chaolang Hu tao lu College of Mathematics Sichuan University Chengdu 610064 China

This article presents approximations of the hypersingular integrals fa^b g（x）（x- t）^adx and fa^b g（x）｜x- t｜dx with arbitrary singular point t C （a, b） and negative fraction number 〈 -1. These general expansions are applicable to a large range of hypersingular inte- grals, including both popular hypersingular integrals discussed in the literature and other important ones which have not been addressed yet. The corresponding mid-rectangular formulas and extrapolations, which can be calculated in fairly straightforward ways, are investigated. Numerical examples are provided to illustrate the features of the numerical methods and verify the theoretical conclusions.

关键词： Hypersingular integral Negative fractional exponent Mid-rectangular quadrature formula Extrapolation.

Removal of dyes from wastewater by growing fungal pellets in a semi-continuous mode

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Frontiers of Chemical Science and Engineering 2017年第3期11卷 338-345页

作者： tao lu Qilei Zhang Shanjing Yao Key Laboratory of Biomass Chemical Engineering of Ministry of Education College of Chemical and Biological Engineering Zhejiang University Hangzhou 310027 China

To increase the efficiency of dye removal from wastewater using mycelial pellets, a bubble column reactor with a simple structure was designed and efficiently used to remove dyes from solution containing dyes. The mycelial pellets were prepared by marine fungus Aspergillus niger ZJUBE-1. Eight dyes were tested as dye targets for the adsorption capacity of mycelial pellets and good removal results were obtained. Eriochrome black T was selected as a model dye for characterizing the adsorption processes in detail. The measurement results of Zeta potential and FT- IR analysis indicate that the electrostatic attraction may play a key role in the biosorption process. The bubble column reactor was utilized to study the batch dye-removal efficiency of mycelial pellets. A re-culture process between every two batches, which was under non-sterile condition, successfully enhanced the utilization of mycelium bio- mass. The dye removal rate is 96.4% after 12 h in the first batch and then decreases slowly in the following batches. This semi-continuous mode, which consists of commutative processes of dye-removal and re-culture, has some outstanding advantages, such as low power consumption, easy operation, high dye removal rate, and efficient biomass utilization.

关键词： dye mycelial pellets marine fungus bubble column reactor semi-continuous biosorption

Inverse Heat Conduction Estimation of Inner Wall Temperature Fluctuations under Turbulent Penetration

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Journal of Thermal Science 2017年第2期26卷 160-165页

作者： GUO Zhouchao lu tao LIU Bo School of Mechanical and Electrical Engineering Beijing University of Chemical TechnologyBeijing100029China Science and Technology on Space Physics Laboratory Beijing100076China

Turbulent penetration can occur when hot and cold fluids mix in a horizontal T-junction pipe at nuclear plants. Caused by the unstable turbulent penetration, temperature fluctuations with large amplitude and high frequency can lead to time-varying wall thermal stress and even thermal fatigue on the inner wall. Numerous cases, however, exist where inner wall temperatures cannot be measured and only outer wall temperature measurements are feasible. Therefore, it is one of the popular research areas in nuclear science and engineering to estimate temperature fluctuations on the inner wall from measurements of outer wall temperatures without damaging the structure of the pipe. In this study, both the one-dimensional(1D) and the two-dimensional(2D) inverse heat conduction problem(IHCP) were solved to estimate the temperature fluctuations on the inner wall. First, numerical models of both the 1D and the 2D direct heat conduction problem(DHCP) were structured in MATLAB, based on the finite difference method with an implicit scheme. Second, both the 1D IHCP and the 2D IHCP were solved by the steepest descent method(SDM), and the DHCP results of temperatures on the outer wall were used to estimate the temperature fluctuations on the inner wall. Third, we compared the temperature fluctuations on the inner wall estimated by the 1D IHCP with those estimated by the 2D IHCP in four cases:(1) when the maximum disturbance of temperature of fluid inside the pipe was 3℃,(2) when the maximum disturbance of temperature of fluid inside the pipe was 30℃,(3) when the maximum disturbance of temperature of fluid inside the pipe was 160℃, and(4) when the fluid temperatures inside the pipe were random from 50℃ to 210℃.

关键词： IHCP SDM Temperature fluctuations Turbulent penetration

Large-eddy Simulation of Fluid Flow and Heat Transfer in a Mixing Tee Junction

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Chinese Journal of Mechanical Engineering 2012年第6期25卷 1144-1150页

作者： lu tao WANG Yongwei WANG Kuisheng School of Mechanical and Electrical Engineering Beijing University of Chemical TechnologyBeijing 100029China

The temperature fluctuation caused by thermal striping phenomena of hot and cold fluids mixing results in cyclical thermal stress fatigue failure of the pipe wall. Mean temperature difference between hot and cold fluids was often used as thermal load in previous analysis of thermal fatigue failure, thereby the influences of the amplitude and frequency of temperature fluctuation on thermal fatigue failure were neglected. Based on the mechanism of flow and heat transfer which induces thermal fatigue, the turbulent mixing of hot and cold water in a tee junction is simulated with FluENT platform by using the Large-eddy simulation（LES） turbulent flow model with the sub-grid scale（SGS） model of Smagorinsky-Lilly（SL） to capture the amplitude and frequency of temperature fluctuation. In a simulation case, hot water with temperature of 343.48 K and velocity of 0.15 m/s enters the horizontal main duct with the side length of 100 mm, while cold water with temperature of 296.78 K and velocity of 0.3 m/s enters the vertical branch duct with the side length of 50 mm. The numerical results show that the mean and fluctuating temperatures are in good agreement with the previous experimental data, which describes numerical simulation with high reliability and accuracy; the power spectrum density（PSD） on top wall is higher than that on bottom wall（as the frequency less than 1 Hz）, while the PSD on bottom wall is relatively higher than that on top wall （as the frequency of 1-10Hz）. The temperature fluctuations in full mixing region of the tee junction can be accurately captured by LES and can provide the theoretical basis for the thermal stress and thermal fatigue analyses.

关键词： Large-eddy simulation flow heat transfer tee junction

Transient Performance Improvement in Tracking Control for a Class of Nonlinear Systems with Input Saturation

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Journal of Systems Science & Complexity 2018年第1期31卷 200-214页

作者： lu tao LAN Weiyao LI Zhibin Department of Automation Xiamen University Xiamen 361005 China Academy of Opto-Electronics Chinese Academy of Sciences Beijing 100094 China

This paper addresses the composite nonlinear feedback（CNF） control for a class of singleinput single-output nonlinear systems with input saturation to track a time varying reference target with good transient performance. The CNF control law consists of a tracking control law and a performance compensator. The tracking control law is designed to drive the output of the system to track the time varying reference target rapidly, while the performance compensator is used to reduce the overshoot caused by the tracking control law. The stability of the closed-loop system is established. The design procedure and the improvement of transient performance of the closed-loop system are illustrated with a numerical example and the controlled Van del Pol oscillator.

关键词： Composite nonlinear feedback input saturation nonlinear systems tracking control

Efficient decolorization of dye-containing wastewater using mycelial pellets formed of marine-derived Aspergillus niger

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Chinese Journal of Chemical Engineering 2017年第3期25卷 330-337页

作者： tao lu Qilei Zhang Shanjing Yao Key Laboratory of Biomass Chemical Engineering of Ministry of Education College of Chemical and Biological EngineeringZhejiang UniversityHangzhou 310027China

In order to improve the efficient decolorization of dye-containing water by biosorbent and understand the biosorption mechanism, the self-immobilization mycelial pellets were prepared using a marine-derived fungus Aspergillus niger ZJUBE-1, and an azo dye, Congo red was chosen as a model dye to investigate batch decolorization efficiency by pellets. The pellets as biosorbent showed strong salt and acid tolerance in biosorption process. The results for dye adsorption showed that the biosorption process fitted well with models of pseudo-second-order kinetic and Langmuir isotherm, with a maximum adsorption capacity of 263.2 mg·g^(-1) mycelium. During 6 batches of continuous decolorization operation, the mycelial pellets could possess efficient decolorization abilities(>98.5%).The appearance of new peak in the UV–Vis spectral result indicated that the decolorization process may also contain biodegradation. The mechanism studies showed that efficient biosorption ability of pellets only relies on the active zone on the surface of the pellet, which can be enhanced by nutrition supplement or be shifted outward by a reculture process.

关键词： Mycelial pellets Batch decolorization Nutrition supplement Re-culture Dye wastewater treatment Adsorption mechanism

Current Oscillation and dc-Voltage-Controlled Chaotic Dynamics in Semiconductor Superlattices

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Communications in Theoretical Physics 2006年第2期45卷 363-368页

作者： WANG Chang lu Jing-tao State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information Technology the Chinese Academy of Sciences Shanghai 200050 China

We report a detailed theoretical study of current oscillation and de-voltage-controlled chaotic dynamics in doped GaAs/AlAs resonant tunneling superlattices under crossed electric and magnetic fields. When the superlattice is biased at the negative differential velocity region, current self-oscillation is observed with proper doping concentration. The current oscillation mode and oscillation frequency can be affected by the dc voltage bias, doping density, and magnetic field. When an ac electric field with fixed amplitude and frequency is also applied to the system, different nonlinear properties show up in the external circuit with the change of dc voltage bias. We carefully study these nonlinear properties with different chaos-detecting methods.

关键词： semiconductor superlattices current oscillation chaotic dynamics

Quantum Chromodynamics Sum Rules for the 1^(-/+) Vector Odd-Glueball

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Chinese Physics Letters 1996年第5期13卷 340-342页

作者： lu Wen-tao LIU Jue-ping Department of Physics Wuhan UniversityWuhan 430072

The transverse part of the two-point function of the 1^(-/+) vector gluonic current is calculated by including the perturbative contributions and the non-perturbative ones resulted from condensates of dimensions up to *** a usual"resonance plus continuum " model of the spectral function,the quantum chromodynamics sum rules for the 1^(-/+) vector odd-glueball are derived,and the 1^(-/+) mass of that glueball is determined to be 1.87 GeV.

关键词： dimensions function transverse