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A Many-Objective Evolutionary Algorithm with Spatial Division and Angle Culling Strategy

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Chinese Journal of Electronics 2021年第3期30卷 437-443页

作者： WANG Hongbo YANG Fan TIAN Kena tu Xuyan School of Computer and Communication Engineering Beijing Key Lab.of Knowledge Engineering for Materials ScienceUniversity of Science and Technology Beijing

In a specific project, how to find a reasonable balance between a plurality of objectives and their optimal solutions has always been an important aspect for researchers. As a trade off between fast convergence and a rich diversity, a Many-objective evolutionary algorithm based on a spatial division and angle-culling strategy(Ma OEA-SDAC) is proposed. In the reorganization stage, a restricted matching selection can enhance the reproductivity. In the environment selection stage, a space division and angle-based elimination strategy can effectively improve the convergence and diversity imbalance of its solution set. Through detailed experiments and a comparative analysis of the proposed Ma OEA-SDAC with five other state-of-the-art algorithms on classical benchmark problems, the effectiveness of Ma OEA-SDAC in solving high-dimensional optimization problems has been verified.

关键词： reasonable balance many-objective evolutionary algorithm convergence environment selection stage angle culling strategy elimination strategy spatial division rich diversity Pareto optimisation angle-culling strategy diversity imbalance restricted matching selection specific project evolutionary computation fast convergence reorganization stage MaOEA-SDAC space division optimal solutions

Experimental and numerical study of installing a dune model in a 90° bend in the horizontal-vertical pneumatic conveying system

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Particuology 2023年第8期79卷 95-108页

作者： Zhenyu Yang Fei Yan Panpan tu Rui Zhu School of Mechanical Engineering Jiangsu University of Science and TechnologyZhenjiang212000China School of Environmental and Chemical Engineering Jiangsu University of Science and TechnologyZhenjiang212000China

In the pneumatic conveying process,particles move to the bend under the influence of inertia to form a particle rope,which will cause serious wear between the particles and the pipe wall,and then the dune model is designed and installed in the 90° bend to reduce energy consumption and wear in this ***,the minimum pressure drop velocity of particles transported by different size dune models was obtained through experimental *** the energy saving mechanism of the dune model is studied by CFD-DEM *** experimental results show that the installation of the dune model reduces the minimum pressure drop *** numerical simulation results show that the number of collisions between the particles and the tube wall in the vertical tube decreases after the installation of the dune model,which reduces the energy ***,the increasing of tail size of the dune model is beneficial to the diffusion and acceleration of the particles in the vertical tube.

关键词： Pneumatic conveying Dune model CFD-DEM Minimum pressure drop velocity Recursiveanalysis

Comparison of Carboxylic Acids in Some Crude Oils and Their Diesel Distillates and VGOs:Characterized by Negative-Ion Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (Negative-Ion ESI FT-ICR MS)

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China Petroleum Processing & Petrochemical Technology 2011年第3期13卷 8-15页

作者： Wang Zhenhua tu Yongshan Process Department China Tianchen Engineering Corporation Tianjin 300400 State Key Laboratory of Heavy Oil Processing China University of Petroleum Qingdao 266555

Three high-acidity crudes, Dar, SZ36-1, and QHD326, were separated through distillation into several fractions, including diesel distillates, and VGOs. Samples were characterized by negative-ion ESI FT-ICR MS. The O2 class species （petroleum carboxylic acids）, which have a close relationship with corrosion of equipment caused by high-acidity crudes, were put in the focus of attention and were discussed in this paper. Monocyclic, bicyclic, and tricyclic naphthenic acids are the main types of petroleum carboxylic acids in naphthenic-base crudes （SZ36-1 and QHD326）. But the main types of petroleum carboxylic acids in paraffinic-base crude （Dar） are aliphatic acids and monocyclic naphthenic acids. The O2 class species in SZ36-1 and QHD326 are distributed in a wider range and have bigger DBE value （double-bond equivalence value） and carbon number than Dar. Bicyclic naphthenic acids have the highest proportion among petroleum carboxylie acids in diesel distillates, but monocyclic and tricyclic naphthenic acids also occupy a high proportion. Particularly, aliphatic acids in the diesel distillate of Dar still have high proportion among petroleum carboxylic acids. The distribution of petroleum carboxylic acids in VGO is basically identical. The bicyclic naphthenic acids assume the first place （about 25 m%）, while the monocyclic and tricyclic naphthenic acids take the next place. The comparison of petroleum carboxylic acids in diesel distillates and VGOs has revealed that the molecules of carboxylic acids in VGOs are not only bigger but also more complicated.

关键词： O2 class species petroleum carboxylic acids aliphatic acids naphthenic acid

Urgent need to address macrolide‑resistant Mycoplasma pneumoniae in pediatric populations:insights from an expert consensus

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World Journal of Pediatrics 2024年第10期20卷 981-982页

作者： Xiwei Wang Wenwei tu Department of Pediatrics&Adolescent Medicine Li Ka Shing Faculty of MedicineUniversity of Hong KongRoom L7‑567/F Laboratory BlockFaculty of Medicine Building21 Sassoon RoadHong KongChina

The increasing prevalence of macrolide-resistant Mycoplasma pneumoniae(MRMP)pneumonia in pediatric patients represents a formidable challenge in contemporary clinical practice,particularly in regions such as East Asia,where resistance rates have alarmingly increased to approximately 70%–90%[1].The rapid spread of MRMP threatens to undermine decades of progress in managing Mycoplasma pneumoniae infections,leading to more severe disease outcomes,longer hospital stays,and increased healthcare costs[2].

关键词： insight approximate resistant

Effect of warm rolling process on microstructures and tensile properties of 10 Mn steel

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Journal of Materials Science & Technology 2020年第12期47卷 131-141页

作者： Bin Hu Xin tu Haiwen Luo Xinping Mao School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

The influence of warm rolling processes on the microstructures and tensile properties of 100 Mn steel was *** appeared to increase with the rolling temperature but strengthening mechanisms *** increase of warm rolling temperature from 250℃ to 600℃ leads to enhanced recrystallization in martensite during the intercritical annealing(IA) at 620℃ for 5 *** a result,both ultimate tensile strength(UTS) and total elongation(TE) ***,the size of relatively coarse recrystallized austenite grains and the resultant yield strength(YS) remain almost constant in this temperature *** further increase of rolling temperature to 700-800℃ causes a considerable amount of pearlite to be formed during the IA,and then martensite is formed after the IA,resulting in dramatical increases in both YS and UTS but at the great loss of *** warm rolling at 600℃ with 63% thickness reduction can produce the steel with the best mechanical combination of 1.2 GPa UTS and 35% TE,due to the formation of many ultrafine austenite grains and strain-induced cementite *** demonstrates that the mechanical combination of non-V-alloyed medium Mn steel can be improved to an equivalent level of 0.7% V alloyed 10 Mn steel just via the economic strain-induced cementite precipitation.

关键词： Warm rolling Cementite precipitation Austenite stability Mechanical properties

A Single-legged Robot Inspired by the Jumping Mechanism of Click Beetles and Its Hopping Dynamics Analysis

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Journal of Bionic Engineering 2020年第6期17卷 1109-1125页

作者： Gang Chen Jiajun tu Xiaocong Ti Huosheng Hu Faculty of Mechanical Engineering and Automation Zhejiang Sci-Tech UniversityHangzhou 310018China School of Computer Science and Electronic Engineering University of EssexColchester C043SQUK

The click beetle can jump up with a hinge when it is on the dorsal *** jumping mechanism is simple and suitable as an inspiration for designing a simple,small,and reliable hopping *** report a single-legged robot inspired by the jumping mechanism of click *** is 85 mm high,60 mm long,and 41 mm wide,and weighs about 49 *** robot has good hopping performance that the hopping height is about 4 times-4.3 times of its body *** is capable for rescue missions that require to enter enclosed spaces through cracks and narrow *** addition,hopping dynamics of the robot is important to understand its jumping mechanism and improve the robot’s hopping *** existing dynamic study does not complete the analysis including all stages in the hopping which are pre-hopping,take-off,and *** propose the decomposition method to study dynamics of the three stages separately,and synthesize them with related *** dynamic synthesis of multi-motion states in a hopping cycle of the single-legged hopping robot is *** hopping performance and dynamic synthesis theory of the robot are verified by simulations and *** study helps lay the foundation for design and hopping control of simple hopping robot systems.

关键词： single-legged hopping robots hopping cycle dynamics synthesis multi-motion states jumping mechanism imitaion of click beetles

Technology of back stoping from level floors in gateway and pillar mining areas of extra-thick seams

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International Journal of Mining Science and Technology 2014年第2期24卷 143-149页

作者： tu Hongsheng tu Shihao Zhang Xiaogang Li Zhaoxin Jia Shuai School of Mines China University of Mining & TechnologyKey Laboratory of Deep Coal Resource MiningMinistry of Education

According to the special requirements of secondary mining of resources in gateway-and-pillar goal in extra-thick seams of Shanxi, this paper presents a technical proposal of back stoping from level floors. Numerical simulation and theoretical analysis are ccsed to investigate the compaction characteristics of cavities under stress as well as an appropriate mining height of the primary-mining layer based on dif- ferent mining widths and pillar widths. For Yangjian coal mine, the mining thickness of the first seam during back stoping from level floor is determined to be 3 m, which meets the relevant requirements. Gateway-and-pillar goaf of a single layer has a range of influence of 9 m vertically. If gateway-and-pillar goaf occurs both in 9-1 and 9-5 layers, the range is extended to within 11.2 m. When the mining width of a gateway is less than 2 m or larger than 5 m, the gateway-and-pillar goal in the upper layer of the primary-mining seam can be filled in and compacted after stoping. When the working face is 2 m away from the gateway and pillar before entering into it and after passing through it, the coal body under the gateway and pillar is subjected to relatively high stress. During mining of the upper layer, moreover, the working face should interlock the goaf in primary-mining layer for 20 m.

关键词： Gateway-and-pillar goaf Back stoping from level floor Secondary mining Numerical simulation Stress evolution

An Improved Torque Sensorless Speed Control Method for Electric Assisted Bicycle With Consideration of Coordinate Conversion

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IEEE/CAA Journal of Automatica Sinica 2020年第6期7卷 1575-1584页

作者： Tinghua Li Qinghua Yang Xiaowei tu Bin Ren School of Mechatronic Engineering and Automation Shanghai UniversityShanghai 200444China

In this paper,we propose an improved torque sensorless speed control method for electric assisted bicycle,this method considers the coordinate conversion.A low-pass filter is designed in disturbance observer to estimate and compensate the variable disturbance during cycling.A DC motor provides assisted power driving,the assistance method is based on the realtime wheel angular velocity and coordinate system *** effect of observer is proved,and the proposed method guarantees stability under *** is also compared to the existing methods and their performances are illustrated through *** proposed method improves the performance both in rapidity and stability.

关键词： Coordinate conversion disturbance observer electric assisted power inertial measurement unit speed control

Experimental Investigation of Heat Storage and Heat Transfer Rates during Melting of Nano-Enhanced Phase Change Materials (NePCM) in a Differentially-Heated Rectangular Cavity

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Journal of Thermal Science 2020年第2期29卷 503-511页

作者： LI Zirui HU Nan tu Jing FAN Liwu Institute of Thermal Science and Power Systems School of Energy EngineeringZhejiang UniversityHangzhou 310027China State Key Laboratory of Clean Energy Utilization Zhejiang UniversityHangzhou 310027China

In this work, an experimental study of melting heat transfer of nano-enhanced phase change materials(NePCM) in a differentially-heated rectangular cavity was performed. Two height-to-width aspect ratios of the cavity, i.e., 0.9 and 1.5, were investigated. The model Ne PCM samples were prepared by dispersing graphene nanoplatelets(GNP) into 1-tetradecanol, having a nominal melting point of 37℃, at loadings up to 3 wt.%. The viscosity was found to have a more than 10-fold increase at the highest loading of GNP. During the melting experiments, the wall superheat at the heating boundary was set to be 10℃ or 30℃. It was shown that with increasing the loading of GNP, both the heat storage and heat transfer rates during melting decelerate to some extent, at all geometrical and thermal configurations. This suggested that the use of NePCM in such cavity may not be able to enhance the heat storage rate due to the dramatic growth in viscosity, which deteriorates significantly natural convective heat transfer during melting to overweigh the enhanced heat conduction by only a decent increase in thermal conductivity. This also suggested that the numerically predicted melting accelerations and heat transfer enhancements, as a result of the increased thermal conductivity, in the literature are likely overestimated because the negative effects due to viscosity growth are underestimated.

关键词： aspect ratio graphene nanoplatelets latent heat storage melting heat transfer phase change material rectangular cavity