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Search Results: 1 - 10 of 22984 matches for " Minghu Yuan "
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Numerical Simulation on Effects of Electromagnetic Force on the Centrifugal Casting Process of High Speed Steel Roll  [PDF]
Minghu Yuan, Leilei Cao, Yaozeng Xu, Xuding Song
Modeling and Numerical Simulation of Material Science (MNSMS) , 2014, DOI: 10.4236/mnsms.2014.41004
A three-dimensional mathematical and physical model coupling with the heat transfer and the flow of molten metal in the centrifugal casting of the high speed steel roll was established by using CFD software FLUENT. It can be used to analyze the distribution of the temperature filed and the flow filed in the centrifugal casting under the gravity, the electromagnetic stirring force and the centrifugal force. Some experiments were carried out to verify the above analysis results. The effects of the electromagnetic force on the centrifugal casting process are discussed. The results showed that under the 0.15 T electromagnetic field intensity, both the absolute pressure of metal flow to mold wall and the metal flow velocity on the same location have some differences between the electromagnetic centrifugal casting and the centrifugal casting. Numerical results for understanding the electromagnetic stirring of the centrifugal casting process have a guiding significance.
Fe-based high temperature superconductivity with Tc=31K bordering an insulating antiferromagnet in (Tl,K)FexSe2 Crystals
Minghu Fang,Hangdong Wang,Chiheng Dong,Zujuan Li,Chunmu Feng,Jian Chen,H. Q. Yuan
Physics , 2010, DOI: 10.1209/0295-5075/94/27009
Abstract: Up to now, there have been two material families, the cuprates and the iron-based compounds with high-temperature superconductivity (HTSC). An essential open question is whether the two classes of materials share the same essential physics. In both, superconductivity (SC) emerges when an antiferromagnetical (AFM) ordered phase is suppressed. However, in cuprates, the repulsive interaction among the electrons is so strong that the parent compounds are "Mott insulators." By contrast, all iron-based parents are metallic. One perspective is that the iron-based parents are weakly correlated and that the AFM arises from a strong "nesting" of the Fermi surfaces. An alternative view is that the electronic correlations in the parents are still sufficiently strong to place the system close to the boundary between itinerancy and electronic localization. A key strategy to differentiate theses views is to explore whether the iron-based system can be tuned into a Mott insulator. Here we identify an insulating AFM in (Tl,K)FexSe2 by introducing Fe-vacancies and creating superconductivity in the Fe-planar. With the increasing Fe-content, the AFM order is reduced. When the magnetism is eliminated, a superconducting phase with Tc as high as 31K (and a Tc onset as high as 40K) is induced. Our findings indicate that the correlation effect plays a crucial role in the iron-based superconductors. (Tl,K)FexSe2, therefore, represents the first Fe-based high temperature superconductor near an insulating AFM.
Revised Phase Diagram for FeTe1-xSex system with less excess Fe atoms
Chihen Dong,Hangdong Wang,Zujuan Li,Jian Chen,H. Q. Yuan,Minghu Fang
Physics , 2010, DOI: 10.1103/PhysRevB.84.224506
Abstract: We observed bulk superconductivity in the FeTe1-xSex crystals with a low Se concentration after the excess Fe atoms existing unavoidably in crystals as-grown are partially removed by means of annealing in the air. A revised magnetism and superconductivity phase diagram is obtained via resistivity and magnetic susceptibility measurements for FeTe1-xSex system. It is found that bulk superconductivity coexists with antiferromagnetic order in the crystals with 0.05
Cluster Analysis Based on Contextual Features Extraction for Conversational Corpus  [PDF]
Qi Chen, Yue Chen, Minghu Jiang
Journal of Computer and Communications (JCC) , 2015, DOI: 10.4236/jcc.2015.35004

Cluster analysis related to computational linguistics seldom concerned with Pragmatics level. Features of corpus on Pragmatics level related to specific situations, including backgrounds, titles and habits. To improve the accuracy of clustering for conversations collected from international students in Tsinghua University, it required contextual features. Here, we collected four-hundred conversations as a corpus and built it to Vector Space Model. With the Oxford-Duden Dictionary and other methods we modified the model and concluded into three groups. We testified our hypothesis through self-organizing map neural network. The result suggested that the modified model had a better outcome.

Optimization of Water Resource Management Using Chooser Option Contracts under Uncertainty  [PDF]
Zhichao Gao, Hong Zhang, Minghu Ha
American Journal of Industrial and Business Management (AJIBM) , 2018, DOI: 10.4236/ajibm.2018.85089
Abstract: Optimization of water resource management is very important to reduce water shortage risk and increase economic benefit. Water option can be used as a flexible instrument in water resource management. In this study, chooser options are designed for water managers to buy additional water in drought periods and sell redundant water in wet periods. To make optimal decisions under uncertainties including probability distributions and intervals, an inexact two-stage mixed-integer programming (ITSMIP) model is applied. To illustrate the role of chooser options in water resource management, a case study is presented. Factors which influence the willingness of buying the chooser options are analyzed and the optimal water allocation plans are also provided. The results demonstrate that chooser options can help water managers mitigate the impact of water shortage and increase utilization efficiency of water resource greatly.
Magnetic and Superconducting Properties of Single Crystals of Fe$_{1+δ}$Te$_{1-x}$Se$_x$ System
Jinhu Yang,Mami Matsui,Masatomo Kawa,Hiroto Ohta,Chishiro Michioka,Chiheng Dong,Hangdong Wang,Huiqiu Yuan,Minghu Fang,Kazuyoshi Yoshimura
Physics , 2009,
Abstract: The spin-fluctuation effect in the Se-substituted system Fe$_{1+\delta}$Te$_{1-x}$Se$_x$ ($x$ = 0, 0.05, 0.12, 0.20, 0.28, 0.33, 0.45, 0.48 and 1.00; $0<\delta < 0.12$) has been studied by the measurements of the X-ray diffraction, the magnetic susceptibility under high magnetic fields and the electrical resistivity under magnetic fields up to 14 T. The samples with $x$ = 0.05, 0.12, 0.20, 0.28, 0.33, 0.45 and 0.48 show superconducting transition temperatures in the ranger of 10 K$\sim$14 K. We obtained their intrinsic susceptibilities by the Honda-Owen method. A nearly linear-in-$T$ behavior in magnetic susceptibility of superconducting samples was observed, indicating the antiferromagnetic spin fluctuations have a strong link with the superconductivity in this series. The upper critical field $\mu_0H_{c2}^{orb}$ for $T\to$ 0 was estimated to exceed the Pauli paramagnetic limit. The Kadowaki-Woods and Wilson ratios indicate that electrons are strongly correlated in this system. Furthermore, the superconducting coherence length and the electron mean free path were also discussed. These superconducting parameters indicate that the superconductivity in the Fe$_{1+\delta}$Te$_{1-x}$Se$_x$ system is unconventional.
Superconductivity at 32K and anisotropy in Tl0.58Rb0.42Fe1.72Se2 crystals
Hangdong Wang,Chihen Dong,Zujuan Li,Shasha Zhu,Qianhui Mao,Chunmu Feng,H. Q. Yuan,Minghu Fang
Physics , 2011, DOI: 10.1209/0295-5075/93/47004
Abstract: Single crystals of Tl0.58Rb0.42Fe1.72Se2 are successfully grown with the superconducting transition temperatures Tconset=32K and Tczero=31.4K. The Hall coefficient exhibits a multi-band behavior, which is very similar to that of all other Fe-based superconductors. We found that the susceptibility at the normal state decreases with decreasing the temperature, indicating a strong antiferromagnetic (AFM) spin fluctuation at the normal state, which might be related to the superconductivity (SC). We also determined the upper critical fields in ab-plane and along c-axis. The anisotropy of the superconductivity determined by the ratio of Hc2ab and Hc2c is estimated to 5.0, which is larger than that in (Ba,K)Fe2As2 and BaFe2-xCoxAs2, but smaller than that in cuprate superconductors.
Sparse Representation for Detection of Microcalcification Clusters
Xinsheng Zhang,Minghu Wang
TELKOMNIKA : Indonesian Journal of Electrical Engineering , 2012, DOI: 10.11591/telkomnika.v10i3.616
Abstract: To improve the performance of microcalcification clusters (MCs) detection, we present an approach to detect MCs in mammograms by casting the detection problem as finding sparse representations of test samples with respect to training samples. The ground truth training samples of MCs in mammograms are assumed to be known as a priori. The sparse representation is computed by the l1-regularized least square approach using the interior-point method. The new method based on sparse representation expresses each testing sample as a linear combination of all the training samples. The sparse coefficient vector is obtained by l1-regularized least square through learning. MCs classification is achieved by defining discriminating functions from the sparse coefficient vector for each category. To investigate its performance, the proposed method is applied to DDSM datasets and compared with support vector machines (SVMs) and twin support vector machines (TWSVMs). The experimental results have shown that the performance of the proposed method is comparable with or better than those methods. In addition, the proposed method is more efficient than SVMs and TWSVMs based methods as it has no need of model selection and parameter optimization.

Jiang Minghu,Lin Biqin,Yuan Baozong,Xu Xiaobin,

电子与信息学报 , 1999,
Abstract: This paper analyzes the reason for low convergence rate of BP network standard backpropagation algorithm to nonblanced training set, researches how to improve the learning algorithm in order to increase training speed, and through two experiments tests and verifies above theory.
Glutamate and γ-aminobutyric acid receptors and their characteristics in retina
Xiongli Yang,Ying Shen,Minghu Han
Chinese Science Bulletin , 1999, DOI: 10.1007/BF02886091
Abstract: Glutamate and γ-aminobutyric acid (GABA) are important neurotransmitters in the retinal neuronal circuitry. Using the whole-cell patch clamp technique and a rapid solution changer, glutamate and GABA receptors in the retina have been extensively investigated. Results indicate that glutamate receptors on horizontal cells may be an AMPA preferring subtype, which predominantly consists of flop splice variants. GABAA and GABAc receptors coexist in bipolar cells, with the latter showing significant desensitization. Kinetics analysis has demonstrated that the activation, deactivation and desensitization of the GABAc receptor-mediated response of these cells are overall slower than those of the GABAA response. Endogenous modulator Zn2 + in the retina has been found to differentially modulate the kinetic characteristics of the GABAC and GABAA responses.
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