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Effects of deoxidizing degree on the pitting corrosion behavior of carbon and manganese steels

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International Journal of Minerals,Metallurgy and Materials 2011年第2期18卷 169-177页

作者： Guo-liang Cao Cuo-min Li Shan Chen Wan-shun Chang Xue-qun Chen college of Sciences Naval University of Engineering Wuhan 430033 China

Nine steels with different deoxidizing degrees and two comparative steels were selected. Their pitting initiation susceptibility was compared by means of potentiodynamic polarization tests in 3wt% NaCl solution. The pit propagation rate was evaluated in artificial sea water and 3wt% sea salt solution by simulating occluded corrosion cell （SOCC） test and hanging plate test, respectively. The composition of inclusions and corrosive feature were studied by scanning electron microscopy （SEM）, electron probe micro-analysis （EPMA）, and optical microscopy （OM）. The results indicate that sulfide inclusions in steel are the sites for pit nucleation. The sulphide inclusions vary in shape from short spindle-like to long strip-like with increasing deoxidizing degree. Under the same conditions, the lower the deoxidizing degree gets, the lower the pitting initiation susceptibility becomes, and the stronger the resistance to pit propagation exhibits. For steels with different deoxidizing degrees, their pitting initiation susceptibility is mainly influenced by thermodynamic stability, while the pit propagation rate is primarily subject to the characteristics of inclusions in steel.

关键词： carbon steel manganese steel pitting deoxidization inclusions

Electrochemical Synthesis and Research of Two Polymers Composed of Alternate Carbazole and Thiophene Units

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Chinese Journal of Chemical Physics 2015年第5期28卷 -页

作者： Qing Cheng Qing-zhen Wen college of Science Naval University of Engineering Wuhan 430033 china

Two organic conjugated molecules composed of central carbazole and bithiophene groups were prepared via the Stille coupling reaction, conductive polymers were prepared by electrochemical method. Structure and photoelectric research of polymers were investigated. 1H NMR and 13C NMR of molecules were consistent with the theorical results, FT-IR showed electrochemical polymeric site were β-position of thiophene units. The smooth morphology and distributed holes were beneficial to improve the electrical conductivity by SEM. When applied voltage was from −0.1 V to 1.2 V, both of the polymer films P1 and P2 showed good electrochromic performances. Compared with P1, P2 had better electrochemical stability and thermal stability due to the better coplanarity by repeated cyclic voltammograms and TGA. The P2 was a promising material in the electrochemical field, meanwhile, it showed that the monomer structure had greatly impact on the performance of polymer.

关键词： Stille reaction Cyclic voltammetry Electrochemistry polymerization Spectroelectrochemistry

Entransy dissipation minimization for generalized heat exchange processes

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维普期刊数据库

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Science China(Technological Sciences) 2016年第10期59卷 1507-1516页

作者： XIA ShaoJun Institute of Thermal Science and Power engineering Naval University of EngineeringWuhan 430033China Military Key Laboratory for naval Ship Power engineering Naval University of EngineeringWuhan 430033China college of Power engineering Naval University of EngineeringWuhan 430033China

This paper investigates the MED （Minimum Entransy Dissipation） optimization of heat transfer processes with the generalized heat transfer law q ∝ （A（T^n））m. For the fixed amount of heat transfer, the optimal temperature paths for the MED are obtained The results show that the strategy of the MED with generalized convective law q ∝ （△T）^m is that the temperature difference keeps constant, which is in accordance with the famous temperature-difference-field uniformity principle, while the strategy of the MED with linear phenomenological law q ∝ A（T^-1） is that the temperature ratio keeps constant. For special cases with Dulong-Petit law q ∝ （△T）^1.25 and an imaginary complex law q ∝ （△（T^4））^1.25, numerical examples are provided and further compared with the strategies of the MEG （Minimum Entropy Generation）, CHF （Constant Heat Flux） and CRT （Constant Reservoir Temperature） operations. Besides, influences of the change of the heat transfer amount on the optimization results with various heat resistance models are discussed in detail.

关键词： entransy theory finite time thermodynamics heat exchange process optimal temperature path generalized heattransfer law generalized thermodynamic optimization

Numerical investigations of the effects of blade shape on the flow characteristics in a stirred dead-end membrane bioreactor

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Journal of Hydrodynamics 2018年第6期30卷 1143-1152页

作者： Xu-qu Hu Xing-yi Wang Xiu-cheng Lei Xiang Qiu Lin-feng Chen State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle Engineering Hunan University college of Science Shanghai Institute of Technology School of naval architecture and Ocean engineering Jiangsu University of Science and Technology

Numerical simulations of turbulent flows in a stirred dead-end membrane bioreactor are performed by using the RNG k-? model based on the finite volume method with the software Fluent. Comparisons of numerical and experimental results confirm the reliability and the feasibility of the constructed model. The flow structures such as the wake flows and the circulation loops in the stirred flows are well simulated. An increase of stirring speed is proposed to minimize the low velocity region. The single vane stirrer is found to be beneficial for biological separations. Results suggest that the increase of the vane number can enhance the mixing effect in the flow domains. However, a circular disk stirrer goes against the formation of vertical circulations. The six-vane stirrer is found to be able to provide a uniform distribution of the high shear stress.

关键词： Turbulent flow stirred flows membrane fouling membrane bioreactor

An Exploration on Adaptive Iterative Learning Control for a Class of Commensurate High-order Uncertain Nonlinear Fractional Order Systems

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IEEE/CAA Journal of Automatica Sinica 2018年第2期5卷 618-627页

作者： Jianming Wei Youan Zhang Hu Bao School of Weaponry engineering Naval University of Engineering college of engineering Yantai Nanshan University Aeronautical college Yantai Nanshan University

This paper explores the adaptive iterative learning control method in the control of fractional order systems for the first time. An adaptive iterative learning control(AILC) scheme is presented for a class of commensurate high-order uncertain nonlinear fractional order systems in the presence of *** facilitate the controller design, a sliding mode surface of tracking errors is designed by using sufficient conditions of linear fractional order systems. To relax the assumption of the identical initial condition in iterative learning control(ILC), a new boundary layer function is proposed by employing MittagLeffler function. The uncertainty in the system is compensated for by utilizing radial basis function neural network. Fractional order differential type updating laws and difference type learning law are designed to estimate unknown constant parameters and time-varying parameter, respectively. The hyperbolic tangent function and a convergent series sequence are used to design robust control term for neural network approximation error and bounded disturbance, simultaneously guaranteeing the learning convergence along iteration. The system output is proved to converge to a small neighborhood of the desired trajectory by constructing Lyapnov-like composite energy function(CEF)containing new integral type Lyapunov function, while keeping all the closed-loop signals bounded. Finally, a simulation example is presented to verify the effectiveness of the proposed approach.

关键词： Index Terms-Adaptive iterative learning control (AILC) boundary layer function composite energy function (CEF) frac-tional order differential learning law fractional order nonlinearsystems Mittag-Leffler function.

Cued search algorithm with uncertain detection performance for phased array radars

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Journal of Systems engineering and Electronics 2013年第6期24卷 938-945页

作者： Jianbin Lu Hui Xiao Zemin Xi Mingmin Zhang Electronic engineering college Naval University of Engineering Air Force Early Warning Academy

A cued search algorithm with uncertain detection performance is proposed for phased array radars. Firstly, a target search model based on the information gain criterion is presented with known detection performance, and the statistical characteristic of the detection probability is calculated by using the fluctuant model of the target radar cross section （RCS）. Secondly, when the detection probability is completely unknown, its probability density function is modeled with a beta distribution, and its posterior probability distribution with the radar observation is derived based on the Bayesian theory. Finally simulation results show that the cued search algorithm with a known RCS fluctuant model can achieve the best performance, and the algorithm with the detection probability modeled as a beta distribution is better than that with a random selected detection probability because the model parameters can be updated by the radar observation to approach to the real value of the detection probability.

关键词： phased array radar detection performance cued search information gain beta distribution

A genetic Gaussian process regression model based on memetic algorithm

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Journal of Central South University 2013年第11期20卷 3085-3093页

作者：张乐刘忠张建强任雄伟 college of Electronic Naval University of Engineering Wuhan Mechanical Technology college

Gaussian process(GP)has fewer parameters,simple model and output of probabilistic sense,when compared with the methods such as support vector *** of the hyper-parameters is critical to the performance of Gaussian process ***,the common-used algorithm has the disadvantages of difficult determination of iteration steps,over-dependence of optimization effect on initial values,and easily falling into local *** solve this problem,a method combining the Gaussian process with memetic algorithm was *** on this method,memetic algorithm was used to search the optimal hyper parameters of Gaussian process regression(GPR)model in the training process and form MA-GPR algorithms,and then the model was used to predict and test the *** used in the marine long-range precision strike system(LPSS)battle effectiveness evaluation,the proposed MA-GPR model significantly improved the prediction accuracy,compared with the conjugate gradient method and the genetic algorithm optimization process.

关键词： Gaussian process hyper-parameters optimization memetic algorithm regression model

Numerical Study on the Pulsation Characteristics of An Attached Air Bubble Under A Nearby Oscillating Bubble

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China Ocean engineering 2023年第2期37卷 299-311页

作者： JIANG Ming-zuo LIU Kun WANG Jia-xia WEN Xiao-hu college of Automation Jiangsu University of Science and TechnologyZhenjiang 212003China School of naval architecture and Ocean engineering Jiangsu University of Science and TechnologyZhenjiang 212003China

Numerical simulations of the non-spherical evolution of a pulsating bubble interacting with a stationary air bubble attached to a fixed structure were performed using a three-dimensional boundary integral method by implementing the mirror image method to simplify the processing of the numerical model. Code validation was accomplished by comparing the numerical results with the laboratory experimental data obtained in our previous study. Complex phenomena were observed, including three types of bubble jet forms, which depended strongly on the distance parameter with respect to the initial location of the bubble from the plate, the bubble strength parameter and the initial air bubble radius parameters. The results of the simulations provide detail insight into interesting bubble jetting phenomena,such as bubble splitting, jets moving away from the plate, and bubble shedding. The dimensionless distance parameter and the initial air bubble radius parameter play a major role in determining the shapes of two bubbles and the jetting direction. The air bubble strength parameter did not change the bubble jet direction but influenced the bubble *** detachment of the attached air bubble under oscillating bubble suction was easily observed for a small initial air bubble. These results showed that bubble jetting toward the plate was manipulated through the effect of attached air bubble, and that cavitation-based applications and underwater explosion bubble may benefit from this erosion mitigation approach.

关键词： bubble dynamics attached air bubble bubble collapse liquid jet

Nonlinear Pre⁃deformation Method for Compressor Rotor Blade

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Journal of Harbin Institute of Technology(New Series) 2021年第4期28卷 49-59页

作者： Yongliang Wang Shihao Li Longkai Zheng Da Kang naval architecture and Ocean engineering college Dalian Maritime UniversityDalian 116026China

A cold compressor blade deforms elastically under aerodynamic and centrifugal loads during operation,transforming into a hot blade *** deformation has a significant effect on the performance of compressor.A nonlinear pre⁃deformation method for compressor rotor blade was developed with consideration of the nonlinear features of blade stiffness and load which varies with blade *** the blade profile design phase,the method can be used to compensate the aeroelastic deformation of the blade during *** adverse effects of blade deflection on compressor performance and structure can be avoided by the pre⁃deformation *** to the fact that the nonlinear method is sensitive to initial value,a load incremental method was applied to calculate initial blade deformation to stabilize and accelerate the pre⁃deformation *** developed method was used to predict the manufactured configuration of the Stage 37 rotor *** variation rules of aerodynamic and structure parameters of the pre⁃deformed blade were analyzed under off⁃design *** show that the developed method ensures that under the design condition there was a good match between the actual blade configuration during operation and the intended design blade *** blade untwist angle of pre⁃deformed blade could be 0°at design ***,the tip clearance only decreased 0.2%.When the working speed was faster than 80%design speed,the performance of the pre⁃deformed blade agreed with that of the design ***,the mass flow rate and the total pressure ratio of the pre⁃deformed blade were lower at low speeds.

关键词： compressor blade pre⁃deformation blade reconstruction fluid⁃structure interaction blade deformation