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Search Results: 1 - 10 of 15099 matches for " Huilong Ren "
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B-Spline Approximation of Ship Waves on the Free Surface  [PDF]
Fang Li, Hui Li, Huilong Ren
Journal of Applied Mathematics and Physics (JAMP) , 2015, DOI: 10.4236/jamp.2015.31011
Abstract:

We consider the problem of a ship advancing in waves. In this method, the zone of free surface in the vicinity of body is discretized. On the discretized surface, the first-order and second-order derivatives of ship waves are represented by the B-Spline formulae. Different ship waves are approximated by cubic B-spline and the first and second order derivates of incident waves are calculated and compared with analytical value. It approves that this numerical method has sufficient accuracy and can be also applied to approximate the velocity potential on the free surface.

Expansion by Laguerre Function for Wave Diffraction around an Infinite Cylinder  [PDF]
Mingdong Lv, Hui Li, Huilong Ren, Xiaobo Chen
Journal of Applied Mathematics and Physics (JAMP) , 2015, DOI: 10.4236/jamp.2015.31010
Abstract:

We consider a vertical circular cylinder on which the vertical variation of water diffraction waves is to be represented by a series of Laguerre functions \"\" ?using Laguerre Polynomials \"\" . The variation is assumed to be of the form \"\"

Study on Spectral Fatigue Assessment of Trimaran Structure
Khurram Shehzad,Ren Huilong,FengGuoqing,Asifa Khurram
Research Journal of Applied Sciences, Engineering and Technology , 2013,
Abstract: This study presents fatigue strength assessment of the trimaran platform by the spectral approach. Spectral fatigue calculations are based on complex stress transfer functions established through direct wave load analysis combined with stress response analysis. In this study, ANSYS software with 3 dimensional linear sea-keeping code AQWA is used to compute frequency response functions of the vessel at zero forward speed. Finite element analysis of global trimaran structure is performed in ANSYS software utilizing hydrodynamic wave loads. Hot spot stress approach is used to compute stress transfer functions of the selected critical details. A MATLAB program, based on direct calculation procedure of spectral fatigue is developed to calculate total fatigue damage using wave scatter data of North Atlantic. Damage incurred during individual heading direction is also calculated and presented by means of polar diagrams to study its contribution towards cumulative fatigue damage.
Towards the Procedure Automation of Full Stochastic Spectral Based Fatigue Analysis
Khurram Shehzad,Ren Huilong,Feng Guoqing,Asifa Khurram
Research Journal of Applied Sciences, Engineering and Technology , 2013,
Abstract: Fatigue is one of the most signi cant failure modes for marine structures such as ships and offshore platforms. Among numerous methods for fatigue life estimation, spectral method is considered as the most reliable one due to its ability to cater different sea states as well as their probabilities of occurrence. However, spectral based simulation procedure itself is quite complex and numerically intensive owing to various critical technical details. Present research study is focused on the application and automation of spectral based fatigue analysis procedure for ship structure using ANSYS software with 3D liner sea keeping code AQWA. Ansys Parametric Design Language (APDL) macros are created and subsequently implemented to automate the workflow of simulation process by reducing the time spent on non-value added repetitive activity. A MATLAB program based on direct calculation procedure of spectral fatigue is developed to calculate total fatigue damage. The automation procedure is employed to predict the fatigue life of a ship structural detail using wave scatter data of North Atlantic and Worldwide trade. The current work will provide a system for efficient implementation of stochastic spectral fatigue analysis procedure for ship structures.
Dual-horizon Peridynamics
Huilong Ren,Xiaoying Zhuang,Yongchang Cai,Timon Rabczuk
Physics , 2015,
Abstract: In this paper we develop a new Peridynamic approach that naturally includes varying horizon sizes and completely solves the "ghost force" issue. Therefore, the concept of dual-horizon is introduced to consider the unbalanced interactions between the particles with different horizon sizes. The present formulation is proved to fulfill both the balances of linear momentum and angular momentum. Neither the "partial stress tensor" nor the "`slice" technique are needed to ameliorate the ghost force issue in \cite{Silling2014}. The consistency of reaction forces is naturally fulfilled by a unified simple formulation. The method can be easily implemented to any existing peridynamics code with minimal changes. A simple adaptive refinement procedure is proposed minimizing the computational cost. The method is applied here to the three Peridynamic formulations, namely bond based, ordinary state based and non-ordinary state based Peridynamics. Both two- and three- dimensional examples including the Kalthof-Winkler experiment and plate with branching cracks are tested to demonstrate the capability of the method in solving wave propagation, fracture and adaptive analysis .
Time Domain Rankine-Green Panel Method for Offshore Structures Time Domain Rankine-Green Panel Method for Offshore Structures
LI Zhifu,REN Huilong,LIU Riming,LI Hui
- , 2017,
Abstract: To solve the numerical divergence problem of the direct time domain Green function method for the motion simulation of floating bodies with large flare, a time domain hybrid Rankine-Green boundary element method is proposed. In this numerical method, the fluid domain is decomposed by an imaginary control surface, at which the continuous condition should be satisfied. Then the Rankine Green function is adopted in the inner domain. The transient free surface Green function is applied in the outer domain, which is used to find the relationship between the velocity potential and its normal derivative for the inner domain. Besides, the velocity potential at the mean free surface between body surface and control surface is directly solved by the integration scheme. The wave exciting force is computed through the convolution integration with wave elevation, by introducing the impulse response function. Additionally, the nonlinear Froude-Krylov force and hydrostatic force, which is computed under the instantaneous incident wave free surface, are taken into account by the direct pressure integration scheme. The corresponding numerical computer code is developed and first used to compute the hydrodynamic coefficients of the hemisphere, as well as the time history of a ship with large flare; good agreement is obtained with the analytical solutions as well as the available numerical results. Then the hydrodynamic properties of a FPSO are studied. The hydrodynamic coefficients agree well with the results computed by the frequency method; the influence of the time interval and the truncated time is investigated in detail
Urgency and Necessity on Adjustment of China’s Current Agricultural Structure Based on the Stability and Developmental Trend Analyses of Pork Yield in China  [PDF]
Cangyu Jin, Huilong Lin
Journal of Agricultural Chemistry and Environment (JACEN) , 2014, DOI: 10.4236/jacen.2014.33B003
Abstract:

With the development of economy, meat gradually plays an important role in Chinese people’s dietary pattern. As the most direct reflection of agricultural system, food system has always been the main output of agricultural system, and pork has occupied an important position in Chinese food system. We attempts to find the systematical disorder of current agricultural system by analyzing the meat output of the agricultural system. H-P Filter and Grey Prediction GM(1,1) Model was adopted to explore the inner rules between pork production and agricultural system in China. The results indicated that pork consumption ratio in Chinese urban residents’ dietary pattern constantly kept about 6%, the growth potential of grain yield is limited while the growth potential of pork yield is increased in China. By Grey Prediction GM(1,1) Model, we predicted the pork yield would reach 59.07 Mt in 2020, 110.25 Mt in 2060, 205.78 Mt in 2100, the demand of feed would reach 177.22 Mt in 2020, 330.75 Mt in 2060, 617.34 Mt in 2100. In China, agricultural system is traditional “pork-grain” mode, feed has been one of the biggest section that consumed grain. The present “pork-grain” agricultural system cannot meet the huge demand of grain from feed, adjusting the agricultural structure is imperative. Reforming the current agricultural system into grassland agricultural system which takes the beef and mutton as predominates would be a good choice for China in the future.

Developing the Agro-Grassland System to Insure Food Security of China  [PDF]
Ruichao Li, Huilong Lin
Journal of Agricultural Chemistry and Environment (JACEN) , 2014, DOI: 10.4236/jacen.2014.33B002
Abstract:

China’s food security has always been the top priority in China. As the huge increase of animal food consumption, the current agriculture system in China namely “grain farming”, whose major animal feed are grains, seems to meet a great challenge to ensure China’s food security in the future. Not only the current situation, but also the production capacity as developing grassland agriculture is analyzed in this paper. The results show that half of provinces don’t have enough grain to meet their various needs for grain, and the whole country’s potential of grain yield is reaching a limited position. On the other hand, implementing cereal-forage rotation on 20% of the total arable land and developing high productivity sown pastures on 3% of the total rangeland areas could create approximately 1.2 times Arable Land Equivalent Unit (ALEU) than ever. So changing the traditional agriculture system into Grassland Agro-Ecosystems is an effective way to insure China’s food security. It includes utilization of rangeland rationally, establishment of more sown pasture and implementation of cereal-pasture rotation system, increase livestock production, and use of arable land more efficiently.

Changes in global potential vegetation distributions from 1911 to 2000 as simulated by the Comprehensive Sequential Classification System approach
TianGang Liang,QiSheng Feng,JianJun Cao,HongJie Xie,HuiLong Lin,Jun Zhao,JiZhou Ren
Chinese Science Bulletin , 2012, DOI: 10.1007/s11434-011-4870-8
Abstract: Vegetation classification models play an important role in studying the response of the terrestrial ecosystem to global climate change. In this paper, we study changes in global Potential Natural Vegetation (PNV) distributions using the Comprehensive Sequential Classification System (CSCS) approach, a technique that combines geographic information systems. Results indicate that on a global scale there are good agreements among maps produced by the CSCS method and the globally well-accepted Holdridge Life Zone (HLZ) and BIOME4 PNV models. The potential vegetation simulated by the CSCS approach has 6 major latitudinal zones in the northern hemisphere and 2 in the southern hemisphere. In mountainous areas it has obvious altitudinal distribution characteristics due to topographic effects. The distribution extent for different PNV classes at various periods has different characteristics. It had a decreasing trend for the tundra and alpine steppe, desert, sub-tropical forest and tropical forest categories, and an increasing trend for the temperate forest and grassland vegetation categories. The simulation of global CSCS-based PNV classes helps to understand climate-vegetation relationships and reveals the dynamics of potential vegetation distributions induced by global changes. Compared with existing statistical and equilibrium models, the CSCS approach provides similar mapping results for global PNV and has the advantage of improved simulation of grassland classes.
Simulation Design of Variable Frequency Speed Regulating System for Automobile Remanufactured Generator Test Bench Based on Matlab  [PDF]
Huilong Lv, Yiping Luo
Open Access Library Journal (OALib Journal) , 2018, DOI: 10.4236/oalib.1104628
Abstract:
There are many types of vehicle generators and their parameters are different. Therefore, the motor selected for the remanufacturing test bench should be suitable for most generators. Therefore, there is a certain requirement for the adjustment range of the motor speed. The AC-DC-AC frequency converter has a large frequency adjustment range, which can meet the motor speed control requirements. In this paper, the Simulink visual simulation tool Simulink modeling and simulation of AC-DC-AC inverter circuit, according to re-manufactured generator test to change the motor-related parameters, and the resulting waveform analysis.
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