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Simulation modeling and experimental analysis of thermodynamic charge performance in a variable-mass thermodynamic system

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Journal of Central South University 2013年第10期20卷 2753-2762页

作者：胡继敏金家善严志腾 college of naval architecture and Power engineering Naval University of Engineering

The thermodynamic charge performance of a variable-mass thermodynamic system was investigated by the simulation modeling and experimental analysis. Three sets of experiments were conducted for various charge time and charge steam flow under three different control strategies of charge valve. Characteristic performance parameters from the average sub-cooled degree and the charging energy coefficient point of views were also defined to evaluate and predict the charge performance of system combined with the simulation model and experimental data. The results show that the average steam flow reflects the average sub-cooled degree qualitatively, while the charging energy coefficients of 74.6%, 69.9% and 100% relate to the end value of the average sub-cooled degree at 2.1, 2.9 and 0 respectively for the three sets of experiments. The mean and maximum deviations of the results predicted from those by experimental data are smaller than 6.8% and 10.8%, respectively. In conclusion, the decrease of average steam flow can effectively increase the charging energy coefficient in the same charge time condition and therefore improve the thermodynamic charge performance of system. While the increase of the charging energy coefficient by extending the charge time needs the consideration of the operating frequency for steam users.

关键词： variable-mass thermodynamic system steam accumulator thermal mixing simulation

An Improved Approach for Interaction of Wave with Floating Spheres and Its Applications

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China Ocean engineering 2023年第1期37卷 115-130页

作者： LIU Can DONG Zhi-yong PAN Yun TONG Huan-huan YANG li-jing college of Civil engineering Zhejiang University of TechnologyHangzhou 310023China School of naval architecture and Maritime Zhejiang Ocean UniversityZhoushan 316022China School of Marine engineering Equipments Zhejiang Ocean UniversityZhoushan 316022China

To develop and utilize marine resources in the deep sea, the higher requirements for floating structures, which are operated in marine environment for a long term, have been put forward. Reasonable structure type and accurate force analysis are favorable guarantees to improve the survival performance and working performance of the floating structures. Floating spheres fastened by mooring cable were widely used in floating structures. In this paper, the wave forces of the floating sphere are efficiently and accurately calculated by solving the geometric relationship between the non-submerged floating sphere and wave surface. Combined with the hydrodynamic calculation of mooring cables based on the lumped mass method, the coupled motion model of multi-floating spheres fastened by multi-mooring cable was established under wave action. Furthermore, according to the floating structures fastened by mooring cable in the actual ocean engineering, the topological method of multi-mooring cables fastening the multifloating spheres was expounded from simple to complex. Finally, the modeling method and preliminarily hydrodynamic characteristics of the fastened floating structures, including the mooring system of renewable energy devices, ocean buoy, and coral nursery, were presented and analyzed in detail. The obtained results showed that the method for calculating the wave force on the floating sphere developed in this paper can accurately describe the motion process of the floating mooring sphere and the force on the mooring cable. Also, the topological method of multiple buoys and multiple mooring cables could efficiently establish various numerical hydrodynamic models of fastened buoys in ocean engineering.

关键词： floating sphere mooring cable wave forces hydrodynamic model ocean engineering

Novel Distance Measures on Hesitant Fuzzy Sets Based on Equal-Probability Transformation and Their Application in Decision Making on Intersection Traffic Control

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Computer Modeling in engineering & Sciences 2023年第5期135卷 1589-1602页

作者： Fangwei Zhang Yi Zhao Jun Ye Shuhong Wang Jingyi Hu naval architecture and port engineering college Shandong Jiaotong UniversityWeihai264209China college of Transport and Communications Shanghai Maritime UniversityShanghai201306China college of Automotive and Traffic engineering Nanjing Forestry UniversityNanjing210037China School of Civil and Environmental engineering Ningbo UniversityNingbo315211China School of Business National University of Singapore118414Singapore Durham Law School Durham UniversityDurhamDH13LEUK

The purpose of this study is to reduce the uncertainty in the calculation process on hesitant fuzzy sets(HFSs).The innovation of this study is to unify the cardinal numbers of hesitant fuzzy elements(HFEs)in a special ***,a probability density function is assigned for any given ***,equal-probability transformation is introduced to transform HFEs with different cardinal numbers on the condition into the same probability density *** characteristic of this transformation is that the higher the consistency of the membership degrees in HFEs,the higher the credibility of the mentioned membership degrees is,then,the bigger the probability density values for them *** to this transformation technique,a set of novel distance measures on HFSs is ***,an illustrative example of intersection traffic control is introduced to show the usefulness of the given distance *** example also shows that this study is a good complement to operation theories on HFSs.

关键词： Hesitant fuzzy sets equal-probability mapping distance measure intersection traffic control cardinality theory

Analysis of the nutation and precession of the vortex core and the influence of operating parameters in a cyclone separator

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Chinese Journal of Chemical engineering 2022年第6期35卷 1-10页

作者： Pan Zhang Guanghui Chen Weiwen Wang Guodong Zhang Huaming Wang college of Electromechanical engineering and Key Laboratory of Multiphase Flow Reaction and Separation engineering of Shandong Province Qingdao University of Science and TechnologyQingdao 266069China college of Chemical engineering Qingdao University of Science and TechnologyQingdao 266043China School of naval architecture and Electrical engineering Zhejiang Ocean UniversityZhoushan 316022China

Vortices motion in the anisotropic turbulent flow of cyclones makes a vital impact on flow stability and collection ***,there remains a lack of clarity in the overall feature of vortices *** this work,a numerical analysis was conducted to clarify the complex motion of the vortex core in a cyclone *** validity of the numerical model was demonstrated by comparing the computational results with experimental data in the *** revealed by the results,the vortex core not only has a precession motion about the geometrical center axis but also does a nutation motion in the axial *** frequencies of the precession motions show two main *** the magnitudes of the precession and nutation motions have non-uniform distributions in the ***,the precession-nutation motions of the vortex cores exhibit a similar fluctuant pattern to the dust ring on the separator *** inlet gas velocity and the inlet solid loading show vital effects on the magnitudes and frequencies of precession and nutation motion.

关键词： Cyclone separator Precession vortex core Nutation motion Separation efficiency Numerical simulation Fluid mechanics

Placement Optimization Method of FPSO Gas Detectors Based on Leakage Risk

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Journal of Ocean University of China 2022年第1期21卷 49-61页

作者： KANG Jichuan SUN Chongwen JIN Peng YAN Fasuo SUN Liping college of Shipbuilding engineering Harbin Engineering UniversityHarbin 150001China Xuzhou Construction Machinery Group Xuzhou 221000China International Joint Laboratory of naval architecture and Offshore Technology Harbin 150001China

As the first step of the fire/gas-detection systems of floating production storage and offloading(FPSO)units is to iden-tify leakage accidents,gas detectors play an important role in controlling the leakage *** improve the leakage scenario detection rate and reduce the cumulative risk value,this paper presents an optimization method of the gas detector *** probability density distribution and cumulative probability density distribution of the leakage source variables and environmental variables were calculated based on the Offshore Reliability Data and the statistical data of the relevant leakage variables.A potential leakage sce-nario set was constructed using Latin hypercube *** typical FPSO leakage scenarios were analyzed through computational fluid dynamics(CFD),and the impacts of different parameters on the leakage were addressed.A series of detectors was deployed according to the simulation *** minimization of the product of effective detection time and gas leakage volume was the risk optimization objective,and the location and number of detectors were taken as decision variables.A greedy extraction heuristic algo-rithm was used to solve the optimization *** results show that the optimized placement had a better monitoring effect on the leakage scenario.

关键词： FPSO leakage risk detector layout optimization Latin hypercube sampling

Influence of Interpenetrating Polymer Networks (IPN) Microstructure on Underwater Acoustic Stealth Performance

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Journal of Wuhan University of Technology(Materials Science) 2010年第2期25卷 272-277页

作者：罗忠 college of naval architecture and Power Naval University of Engineering

According to the configuration and absorption theory of polymer macromolecule materials, a kind of IPN with wider temperature range and higher damping property was designed and synthesized. By using the spectrum of dynamic mechanical thermal analysis （DMTA） and acoustic pulse tube device, the microstructure, phase separation degree, phase size and phase continuity of IPN with different components were analyzed. The experimental results show that the nano size grade of phase, the continuous and homogeneous IPN phase can provide higher absorption coefficient. The absorption coefficient of optimized sample I09 is 0.7 in 2 kHz, and the absorption peak is 0.9 in 4 kHz. Then the underwater acoustic properties of modified IPN filled with mica, micro-balloon and nano-SiO2 were discussed respectively to indicate that the inhomogeneous property of filler-modified IPN can improve the underwater acoustic stealth performance effectively, and the micro size grade of these filler-modified IPN can work well in low frequency acoustic stealth.

关键词： interpenetrating polymer networks (IPN) polyurethane damping absorption coefficient fillers

A Coiflet Wavelet Homotopy Technique for Nonlinear PDEs:Application to the Extreme Bending of Orthotropic Plate with Forced Boundary Constraints

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Advances in Applied Mathematics and Mechanics 2023年第6期15卷 1473-1514页

作者： Qiang Yu Shuaimin Wang Junfeng Xiao Hang Xu college of Ocean Science and engineering Shanghai Maritime UniversityShanghai 201306China School of naval architecture Ocean and Civil engineering Shanghai Jiao Tong UniversityShanghai 200240China

A generalized homotopy-based Coiflet-type wavelet method for solving strongly nonlinear PDEs with nonhomogeneous edges is *** on the improvement of boundary difference order by Taylor expansion,the accuracy in wavelet approximation is largely improved and the accumulated error on boundary is successfully suppressed in application.A unified high-precision wavelet approximation scheme is formulated for inhomogeneous boundaries involved in generalized Neumann,Robin and Cauchy types,which overcomes the shortcomings of accuracy loss in homogenizing process by variable *** deflection bending analysis of orthotropic plate with forced boundary moments and rotations on nonlinear foundation is used as an example to illustrate the wavelet approach,while the obtained solutions for lateral deflection at both smally and largely deformed stage have been validated compared to the published results in good *** to the other homotopy-based approach,the wavelet scheme possesses good efficiency in transforming the differential operations into algebraic ones by converting the differential operators into iterative matrices,while nonhomogeneous boundary is directly approached dispensing with *** auxiliary linear operator determined by linear component of original governing equation demonstrates excellent approaching precision and the convergence can be ensured by iterative approach.

关键词： Wavelet method higher-order interpolating continuation homotopy analysis method geometric nonlinearity orthotropic plate

Low-Temperature Synthesis of Nano-AlN Based on Solid Nitrogen Source by Plasma-Assisted Ball Milling

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Journal of Renewable Materials 2023年第6期11卷 2941-2951页

作者： Zhuoli Yang Xianbin Hou Leyang Dai Xiamen Ocean Vocational college Xiamen361100China Fujian Provincial Key Laboratory of naval architecture and Ocean engineering Institute of Marine EngineeringJimei UniversityXiamen361100China

Plasma-assisted ball milling was carried out on the Al+C3H6N6 system and Al+C_(4)H_(4)N_(4) system,*** phase structure,functional groups and synthesis mechanism were analyzed by XRD and FT-IR,and the differences in the synthesis process of nano-AlN with different solid nitrogen sources were *** results show that C3H6N6 has a stable triazine ring structure,and its chemical bond is firm and difficult to break,so AlN cannot be synthesized directly by solid-solid reaction at room ***,there are a large number of nitrile groups(-CN)and amino groups(-NH_(2))in C_(4)H_(4)N_(4) *** the combined action of plasma bombardment and mechanical energy activation,C_(4)H_(4)N_(4) molecules undergo polycondensation and deamination,so that the ball milling tank is filled with a large number of active nitrogen-containing groups such as N=,≡N,*** groups and ball milling activated Al can synthesize nano-AlN at room temperature,with a conversion rate of 92%.SEM,DSC/TG analysis showed that the powder obtained by ball milling was formed by soft agglomeration of many fine primary particles about 50–80 *** surface morphology of the powder was loose and porous,and it had strong *** annealing at 800℃,the conversion rate of the Al+C_(4)H_(4)N_(4) system reached 99%.

关键词： Plasma-assisted ball milling solid nitrogen source melamine(C_(3)H_(6)N_(6)) aluminum nitride(AlN) low-temperature synthesis

Study on the Characteristics of A New Hybrid Mooring System for DualPlatform Joint Operations

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China Ocean engineering 2023年第3期37卷 506-518页

作者： SHEN Zhong-xiang YUAN Zhao-jun LI Hong-bin ZHU Chen-yang School of naval architecture and Ocean engineering Jiangsu University of Science and TechnologyZhenjiang 212100China college of Harbor Coastal and Offshore EngineeringHohai UniversityNanjing 210098China Nantong COSCO KHI Ship engineering Co.Ltd Nantong 226005China

As the sustainable exploitation of marine resources develops,dual-platform joint operation has caught increasing ***-platform joint operation requires smaller relative motion between the two sub-platforms,which is normally difficult to be satisfied by the traditional mooring ***,a new hybrid mooring system is developed and studied in this *** ensure safety during platform movements,both the number of anchor chains and the relative motion between the two sub-platforms are reduced in the new hybrid mooring *** performing numerical simulations based on three-dimensional potential flow theory in AQWA and physical experiments,the performances of both the new hybrid and traditional mooring systems under two different wave conditions(i.e.,working wave and freak wave conditions) are systematically *** the new hybrid mooring system,the relative stability between the two sub-platforms of the new system is better,and the platforms can restore stability faster when affected by freak waves.

关键词： dual-platform joint operation platform relative stability hybrid mooring system freak wave