152,876 research outputs found

    Acyclic orientations on the Sierpinski gasket

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    We study the number of acyclic orientations on the generalized two-dimensional Sierpinski gasket SG2,b(n)SG_{2,b}(n) at stage nn with bb equal to two and three, and determine the asymptotic behaviors. We also derive upper bounds for the asymptotic growth constants for SG2,bSG_{2,b} and dd-dimensional Sierpinski gasket SGdSG_d.Comment: 20 pages, 8 figures and 6 table

    Enhanced crystallinity of low temperature deposited silicon films on graphite subtrates

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    The previously developed technique of a sandwich coating for silicon crystallinity enhancement in silicon films deposited at low temperature is applied to graphite substrates. The measured increase in silicon crystallinity is comparable to that observed earlier using a quartz substrate. The distribution of aluminum in the silicon films is determined using Auger spectroscopic depth profiling. Carbon diffusion from the substrate into the silicon film is shown to be negligible at a substrate temperature of 600 C

    Structure of the Partition Function and Transfer Matrices for the Potts Model in a Magnetic Field on Lattice Strips

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    We determine the general structure of the partition function of the qq-state Potts model in an external magnetic field, Z(G,q,v,w)Z(G,q,v,w) for arbitrary qq, temperature variable vv, and magnetic field variable ww, on cyclic, M\"obius, and free strip graphs GG of the square (sq), triangular (tri), and honeycomb (hc) lattices with width LyL_y and arbitrarily great length LxL_x. For the cyclic case we prove that the partition function has the form Z(Λ,Ly×Lx,q,v,w)=d=0Lyc~(d)Tr[(TZ,Λ,Ly,d)m]Z(\Lambda,L_y \times L_x,q,v,w)=\sum_{d=0}^{L_y} \tilde c^{(d)} Tr[(T_{Z,\Lambda,L_y,d})^m], where Λ\Lambda denotes the lattice type, c~(d)\tilde c^{(d)} are specified polynomials of degree dd in qq, TZ,Λ,Ly,dT_{Z,\Lambda,L_y,d} is the corresponding transfer matrix, and m=Lxm=L_x (Lx/2L_x/2) for Λ=sq,tri(hc)\Lambda=sq, tri (hc), respectively. An analogous formula is given for M\"obius strips, while only TZ,Λ,Ly,d=0T_{Z,\Lambda,L_y,d=0} appears for free strips. We exhibit a method for calculating TZ,Λ,Ly,dT_{Z,\Lambda,L_y,d} for arbitrary LyL_y and give illustrative examples. Explicit results for arbitrary LyL_y are presented for TZ,Λ,Ly,dT_{Z,\Lambda,L_y,d} with d=Lyd=L_y and d=Ly1d=L_y-1. We find very simple formulas for the determinant det(TZ,Λ,Ly,d)det(T_{Z,\Lambda,L_y,d}). We also give results for self-dual cyclic strips of the square lattice.Comment: Reference added to a relevant paper by F. Y. W

    Two-directional active damper

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    Damper system to be used in studies of payload isolation technology is suitable as a laboratory apparatus. It provides easily adjustable damping and acts as multichannel shaker system

    Is there a resting frame in the universe? A proposed experimental test based on a precise measurement of particle mass

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    According to the Special Theory of Relativity, there should be no resting frame in our universe. Such an assumption, however, could be in conflict with the Standard Model of cosmology today, which regards the vacuum not as an empty space. Thus, there is a strong need to experimentally test whether there is a resting frame in our universe or not. We propose that this can be done by precisely measuring the masses of two charged particles moving in opposite directions. If all inertial frames are equivalent, there should be no detectable mass difference between these two particles. If there is a resting frame in the universe, one will observe a mass difference that is dependent on the orientation of the laboratory frame. The detailed experimental setup is discussed in this paper.Comment: 9 pages, 4 figure

    Dopant gas effect on silicon chemical vapor depositions: A surface potential model

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    A surface potential model is proposed to consistently explain the known dopant gas effects on silicon chemical vapor deposition. This model predicts that the effects of the same dopant gases on the diamond deposition rate using methane and carbon tetrachloride should be opposite and similar to those of silane, respectively. Available data are in agreement with this prediction

    The NLO QCD Corrections to BcB_c Meson Production in Z0Z^0 Decays

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    The decay width of Z0Z^0 to BcB_c meson is evaluated at the next-to-leading order(NLO) accuracy in strong interaction. Numerical calculation shows that the NLO correction to this process is remarkable. The quantum chromodynamics(QCD)renormalization scale dependence of the results is obviously depressed, and hence the uncertainties lying in the leading order calculation are reduced.Comment: 14 pages, 7 figures; references added; expressions and typos ammende

    Mechanical behavior of thermal barrier coatings for gas turbine blades

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    Plasma-sprayed thermal barrier coatings (TBCs) will enable turbine components to operate at higher temperatures and lower cooling gas flow rates; thereby improving their efficiency. Future developments are limited by precise knowledge of the material properties and failure mechanisms of the coating system. Details of this nature are needed for realistic modeling of the coating system which will, in turn, promote advancements in coating technology. Complementary experiments and analytical modeling which were undertaken in order to define and measure the important failure processes for plasma-sprayed coatings are presented. The experimental portion includes two different tests which were developed to measure coating properties. These are termed tensile adhesion and acoustic emission tests. The analytical modeling section details a finite element method which was used to calculate the stress distribution in the coating system. Some preliminary results are presented
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