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APC: Only $99 Submit 2020 ( 38 ) 2019 ( 272 ) 2018 ( 1492 ) 2017 ( 1341 ) Search Results: 1 - 10 of 81181 matches for " Xiaochun Liu " All listed articles are free for downloading (OA Articles)  Page 1 /81181 Display every page 5 10 20 Item  Journal of Industrial Engineering and Management , 2013, DOI: 10.3926/jiem.678 Abstract: Purpose: In recent years the problem of traffic congestion and its management has become increasingly prominent. It is a hot research about how to make full use of computer simulation technology to make transportation more rational and more organized. In this paper, we focus on traffic of Beijing West Railway Station north area, and try to find a way to reduce traffic congestion in this area. Approach: In this paper, we studied the traffic flow by survey. We also built a traffic simulation model with VISSIM software. Different types of vehicles and their speed are set in model according survey data. The simulation model provides different traffic scenarios of Beijing West Railway Station north area. Findings: We found the traffic of this area up is to 1800 vehicles/hour. Heavy traffic burden causes traffic congestion in two positions: the bus hub and car drop-off point. If we can extend bus interval departure time and park cars to south square of Beijing West Railway Station, the traffic condition will be improved. Originality: This paper gives a solution to reduce traffic congestion in Beijing West Railway Station north area. The bus hub and car parking lots are the key point of traffic problem in this area.  Mathematics , 2014, Abstract: This paper is devoted to prove the existence and nonexistence of positive solutions for a class of fractional Schrodinger equation in RN of the We apply a new methods to obtain the existence of positive solutions when f(u) is asymptotically linear with respect to u at infinity.  Mathematics , 2014, Abstract: We establish the existence and multiplicity of positive solutions to the problems involving the fractional Laplacian: \begin{equation*} \left\{\begin{array}{lll} &(-\Delta)^{s}u=\lambda u^{p}+f(u),\,\,u>0 \quad &\mbox{in}\,\,\Omega,\\ &u=0\quad &\mbox{in}\,\,\mathbb{R}^{N}\setminus\Omega,\\ \end{array}\right. \end{equation*} where$\Omega\subset \mathbb{R}^{N}(N\geq 2)$is a bounded smooth domain,$s\in (0,1)$,$p>0$,$\lambda\in \mathbb{R}$and$(-\Delta)^{s}$stands for the fractional Laplacian. When$f$oscillates near the origin or at infinity, via the variational argument we prove that the problem has arbitrarily many positive solutions and the number of solutions to problem is strongly influenced by$u^{p}$and$\lambda$. Moreover, various properties of the solutions are also described in$L^{\infty}$- and$X^{s}_{0}(\Omega)\$-norms.
 Journal of Materials Science and Chemical Engineering (MSCE) , 2015, DOI: 10.4236/msce.2015.39005 Abstract: Cryogenic treatment has been increasingly applied to enhance the hardness, antiwear ability and fatigue performance of die steel. On the basis of reading a large number of research papers and references across the world, the author makes a detailed analysis and brief summary of the influence of cryogenic treatment on microstructure after quenching process or quenching plus tempering process, on first and second carbides, on content of retained austenite, on surface hardness, on mechanical properties and antiwear ability of die steels. It’s proved that cryogenic treatment on die steel significantly improves its hardness, antiwear capacity and service life. It’s the cryogenic process to make die steel have higher hardness, better antiwear ability, better ductility and longer service life because cryogenic process actually has a good influence on die steel of its microstructure, retained austenite volume and amount and size of the second carbide.
 Art and Design Review (ADR) , 2017, DOI: 10.4236/adr.2017.53012 Abstract: This paper incorporates the Service Design Thinking into the exhibition space design to refine the generality between service design and the display design, and carry out the design practice by combining the science exhibition technology of the aging assistive technology to refine the influence factor and the design method between the service design and the exhibition effect. It explores how to apply the service design thinking efficiently in the concrete practices of the exhibition space design.
 Xiaochun Mei International Journal of Astronomy and Astrophysics (IJAA) , 2011, DOI: 10.4236/ijaa.2011.14023 Abstract: The true meaning of the constant in the Robertson-Walker metric is discussed when the scalar factor s the function of time. By strict calculation based on the Riemannian geometry, it is proved that the spatial curvature of the R-W metric is K=(κ-R2)/R2 . The result indicates that the R-W metric has no constant curvature when R(t)≠0 and κ is not spatial curvature factor. We can only consider κ as an adjustable parameter with κ≠0 in general situations. The result is completely different from the current understanding which is based on the precondition that the scalar factor R(t) is fixed. Due to this result, many conclusions in the current cosmology such as the densities of dark material and dark energy should be re-estimated. In this way, we may overcome the current puzzling situation of cosmology thoroughly.
 Xiaochun Mei Journal of Modern Physics (JMP) , 2012, DOI: 10.4236/jmp.2012.31006 Abstract: According to the current understanding, electromagnetic interaction is invariable under time reversal. However, the proof of time reversal symmetry in quantum theory of field has not considered the effects of high order perturbation normalizations. It is proved in the paper that when the renormalization effect of third order vertex angles process is taken into account, the symmetry of time reversal will be violated in electromagnetic interaction process. Because the magnitude order of symmetry violation is about 10–5, but the precision of current experiments on time reversal in particle physics is about 10–3, this kind of symmetry violation can not be found. The result reveals the micro-origin of asymmetry of time reversal and can be used to solve the famous irreversibility paradox in the evolution processes of macro- material systems.
 Xiaochun Mei Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.47131 Abstract: In the classical Newtonian mechanics, the gravity fields of static thin loop and double spheres are two simple but foundational problems. However, in the Einstein’s theory of gravity, they are not simple. In fact, we do not know their solutions up to now. Based on the coordinate transformations of the Kerr and the Kerr-Newman solutions of the Einstein’s equation of gravity field with axial symmetry, the gravity fields of static thin loop and double spheres are obtained. The results indicate that, no matter how much the mass and density are, there are singularities at the central point of thin loop and the contact point of double spheres. What is more, the singularities are completely exposed in vacuum. Space near the surfaces of thin loop and spheres are highly curved, although the gravity fields are very weak. These results are inconsistent with practical experience and completely impossible. By reasonable analogy, black holes with singularity in cosmology and astrophysics are something illusive. Caused by the mathematical description of curved space-time, they do not exist in real world actually. If there are black holes in the universe, they can only be the types of the Newtonian black holes without singularities, rather than the Einstein’s singularity black holes. In order to escape the puzzle of singularity thoroughly, the description of gravity should return to the traditional form of dynamics in flat space. The renormalization of gravity and the unified description of four basic interactions may be possible only based on the frame of flat space-time. Otherwise, theses problems can not be solved forever. Physicists should have a clear understanding about this problem.
 Xiaochun Mei Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.58071 Abstract: It is proved in this paper that there are at least five situations in the interaction theories of microparticle physics that the Lorentz transformations have no invariabilities. 1) In the formula to calculate transition probabilities in particle physics, the so-called invariability factor of phase space d3p/E is not invariable actually under the Lorentz transformations. Only in one-dimensional motion with uy = uz = 0, it is invariable. 2) The propagation function of spinor field in quantum theory of field has no invariability of Lorentz Transformation actually. What appears in the transformation is the sum of Lorentz factors aμνaλμ ≠ δνλ when ν, λ = 1, 4, rather than aμνaλμ = δνλ. But in the current
 Xiaochun Mei International Journal of Astronomy and Astrophysics (IJAA) , 2014, DOI: 10.4236/ijaa.2014.44060 Abstract: Based on general relativity, J. R. Oppenheimer proved that massive celestial bodies may collapse into singular black holes with infinite densities. By analyzing the original paper of Oppenheimer, this paper reveals that the calculations had a series and serious of mistakes. The basic problem is that the calculation supposes that the density of celestial body does not change with space-time coordinates. The density is firstly assumed invariable with space coordinates and then it is assumed invariable with time. But at last, the conclusion that the density of a celestial body becomes infinity is deduced. The premise contradicts with conclusion. In fact, there is no restriction on the initial density and radius for celestial body in the calculation. According to the calculation results of Oppenheimer, a cloud of thin gas may also collapse into singular black hole under the action of gravity. The calculations neglect great rotating speeds of massive and high density celestial bodies which would make them falling apart rather than collapsing into singularities. Because we do not know the function relations that material densities depend on space-time coordinates in advance, there exists the rationality problem of procedure using the Einstein’s equation of gravity field to calculate material collapse. Besides these physical problems, the calculation of Oppenheimer also has some obvious mistakes in mathematics. Another improved method to calculate massive celestial body’s collapse also has similar problems. The results are also unreliable. The conclusion of this paper is that up to now general relativity actually has not proved that massive celestial bodies may collapse into singularity black holes.
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