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Search Results: 1 - 10 of 127065 matches for " Jingfeng Li "
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Dynamic Coal Logistics Facility Location under Demand Uncertainty  [PDF]
Jiang Wu, Jingfeng Li
Open Journal of Social Sciences (JSS) , 2014, DOI: 10.4236/jss.2014.29006
Abstract:

In this paper, dynamic facility location and supply chain planning are studied through minimizing the costs of facility location, path selection and transportation of coal under demand uncertainty. The proposed model dynamically incorporates possible changes in transportation network, facility investment costs, operating cost and changes in facility location. In addition, the time variation and the demand uncertainty for coal in each period of the planning horizon is taken into account to determine the optimal facility location and the optimal production volumes. Computational process and results are presented for the model in a java language. Also, an empirical case study in Shanxi province is conducted in order to investigate the dynamic effects of traffic congestion and demand uncertainty on facility location design and total system costs.

Fabrication and Analysis of Vanadium-Based Metal Powders for Selective Laser Melting  [PDF]
Jialin Yang, Jingfeng Li
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2018, DOI: 10.4236/jmmce.2018.61005
Abstract: Vanadium Alloy is a type of advanced nuclear material with many ideal properties compared as traditional nuclear materials, which has very wide and important application in first-wall and blanket structural material for fusion power plant applications. So it has attracted increasing attentions, especially on new manufacturing methods, such as selective laser melting and so on. In this paper, the comparative study of the powders obtained by mechanical mixing method, dry grinding method and wet grinding method respectively was performed to evaluate the effect of ball milling process on the microstructure and degree of alloying of the vanadium-based powder mixtures with the nominal composition of V5Cr5Ti vanadium alloy. The powders prepared by dry grinding method exhibits better spherical-like morphology and degree of alloying than those prepared by mechanical mixing method and wet grinding method, which indicates that dry grinding method can be used to prepare the superfine vanadium alloy powders for selective laser melting. This work provides a new method as well as important insights into the preparation of superfine vanadium alloy powders for selective laser melting additive manufacturing technology.
A bulk metal/ceramic composite material with a cellular structure
Zhankui Zhao,Kefu Yao,Jingfeng Li
Chinese Science Bulletin , 2006, DOI: 10.1007/s11434-004-0491-9
Abstract: A bulk metal/ceramic composite material with a honeycomb-like micro-cell structure has been prepared by sintering the spherical Al90Mn9Ce1 alloy powders clad by Al2O3 nano-powder with the spark plasma sintering (SPS) technique. The as-prepared material consists of Al90Mn9Ce1 alloy cell and closed Al2O3 ceramic cell wall. The diameter of the cells is about 20–40 μm, while a thickness of the cell wall is about 1–2 μm. The ultimate compressive strength of the as-sintered materials is about 514 MPa, while its fracture strain is up to about 0.65 %. This composite material might possess good anti-corrosion, thermal endurance and other potential properties due to its unique microstructure. The result shows that the Al90Mn9Ce1/Al2O3 composite powders can be sintered by spark plasma sintering technique despite the large difference in their sintering temperature. This work offers a way of designing and preparing metal/ceramic composite material with functional property.
Fabrication and property of high-performance Ag-Pb-Sb-Te system semiconducting thermoelectric materials
Min Zhou,JingFeng Li,Heng Wang
Chinese Science Bulletin , 2007, DOI: 10.1007/s11434-007-0124-1
Abstract: High performance Ag-Pb-Sb-Te system thermoelectric bulk materials were fabricated by a combination of mechanical alloying (MA) and spark plasma sintering (SPS). Phase composition and microstructure of the resultant materials were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. A special emphasis was paid to the effects of chemical composition, especially the Pb content on the thermoelectric properties of the Ag0.8Pb18+x SbTe20 samples, including electrical resistivity, Seebeck coefficient, power factor, thermal conductivity and dimensionless figure of merit. The present study reveals that the optimal composition of Ag0.8Pb18+x SbTe20 samples is Ag0.8Pb22.5SbTe20 and the maximum figure of merit (ZT) is 1.2 at 673 K.
Finite-element Analysis and Optimization for the Column of Numerically Controlled Triaxial Deep Hole Drilling Machine
Dezhong Kong,Jingfeng Shen,Baohui Li
Mechanical Engineering Research , 2012, DOI: 10.5539/mer.v2n1p107
Abstract: Solidworks is selected for modeling the 3D-solid structure of the deep-hole drilling machine. Based on parametric modeling and structural optimization theory, the parametric model of column is established. The equivalent stress and maximum principal stress on the column are solved by FEA. The two parameters (column thickness and inner rib thickness) are included. According to the design variables, the main target method is applied for the purpose of optimizing the weight of the column (Chen, Ding, & Guo, 2010). Topology optimization is used to determine the location of the sand holes by ansys software with density method.
Finite Element Analysis and Structure Optimal Design of the Column of Deep-Hole Drilling Machine
Baohui Li,Jingfeng Shen,Zhidong Zhang
Modern Applied Science , 2011, DOI: 10.5539/mas.v5n5p196
Abstract: Solidworks is selected for modeling the 3D-solid structure of the column of the deep-hole drilling machine, as well as solidworks simulation for the analysis of the casting model. For the purpose of optimizing the weight of the column, two parameters (column thickness and inner rib thickness) are included and three optimal design methods are compared in the event that the column stiffness and displacement are under control.
Design of Controller in Electric Bicycle
Zhidong Zhang,Jingfeng Shen,Baohui Li
Modern Applied Science , 2011, DOI: 10.5539/mas.v5n5p125
Abstract: Base on PIC16F72, a design of brushless DC motor controller strategy applied to the electric bicycle control system was presented in the paper. Through analyzed some possible problems when electric bicycle running daily. Function of over-current protection, under-voltage protection and helping were accomplished. Schematic diagrams of each function and drive circuit were given in the paper, the controller was debugged in rated voltage 36V and power rating 250W brushless DC motor, experiment turned out controller has better dynamic characteristics and ran steadily.
A bulk metal/ceramic composite material with a cellular structure
ZHAO Zhankui,YAO Kefu,LI Jingfeng,
ZHAO
,Zhankui,YAO,Kefu,LI,Jingfeng

科学通报(英文版) , 2006,
Abstract: A bulk metal/ceramic composite material with a honeycomb-like micro-cell structure has been prepared by sintering the spherical Al90Mn9Ce1 alloy powders clad by Al2O3 nano-powder with the spark plasma sintering (SPS) technique. The as-prepared material consists of Al90Mn9Ce1 alloy cell and closed Al2O3 ceramic cell wall. The diameter of the cells is about 20–40 μm, while a thickness of the cell wall is about 1–2 μm. The ultimate compressive strength of the as-sintered materials is about 514 MPa, while its fracture strain is up to about 0.65 %. This composite material might possess good anti-corrosion, thermal endurance and other potential properties due to its unique microstructure. The result shows that the Al90Mn9Ce1/Al2O3 composite powders can be sintered by spark plasma sintering technique despite the large difference in their sintering temperature. This work offers a way of designing and preparing metal/ceramic composite material with functional property.
12Gb/s 0.25μm CMOS Low-Power 1∶4 Demultiplexer
Ding Jingfeng,Wang Zhigong,Zhu En,Zhang Li,Wang Gui
半导体学报 , 2006,
Abstract: 实现了一种能运用于光传输系统SONET OC-192的低功耗单级分接器,其工作速率高达12Gb/s. 该电路采用了特征栅长为0.25μm的TSMC混和信号CMOS工艺. 所有的电路都采用了源极耦合逻辑,在抑制共模噪声的同时达到尽可能高的工作速率. 该分接器具有利用四分之一速率的正交时钟来实现单级分接的特征,减少了分接器器件,降低了功耗. 通过在晶圆测试,该芯片在输入12Gb/s长度为231-1伪随机码流时,分接功能正确. 芯片面积为0.9mm×0.9mm,在2.5V单电源供电的情况下的典型功耗是210mW.
Structured dictionary learning based on group sparsity
基于群稀疏的结构化字典学习

Guo Jingfeng,Li Xian,
郭景峰
,李贤

中国图象图形学报 , 2012,
Abstract: Sparse representation of signals is an evolving field in many machine learning and image processing tasks. Nowadays, more and more attention is paid on the algorithm for learning dictionaries.Traditionally, the dictionary is an unstructured set of atoms. Considering the sparsity of the group of the sparse representation signal, a mathematical model of the dictionary learning based on the group sparsity is constructed. We propose an efficient algorithm for learning structured dictionary according to the convex analysis and monotone operator theory. The experiments show that the algorithm converges faster, the dictionary trained from the new model adapts better to the data and the data is better represented, which overall improves the image enhancement effect.
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