Ku-band long distance site-diversity (SD) Characteristics using new measuring system

Abstract—This paper deals with the short (10 km) and long dis-tance (300–1400 km) site-diversity (SD) characteristics by using a newly developed measuring system. In the proposed measuring system, six earth stations transmit 14-GHz band QPSK signals, and one measuring earth station receives 12-GHz band signals and processes them to determine SD characteristics. As a result, easy operation and maintenance, low-cost measuring system construc-tion and highly accurate data have been obtained. By comparing those measured results with the SD joint probability approxima-tion equation in ITU-R Rec.P.618-7, a good agreement can be ob-tained. Furthermore, the effect of typhoons on SD characteristics were measured. Index Terms—Rain attenuation, satellite communication system, site-diversity (SD) measurement system, SD characteristics, VSAT system design. I

Super Yang-Mills Theory from a Supermatrix Model

It is known that Yang-Mills theories on non-commutative space can be derived from large-N reduced models. Gauge fields in non-commutative Yang-Mills theories can be described as fluctuations of matrices expanded about an appropriate classical solution of the reduced models. We investigate a generalization of this procedure in superfield formalism. We show that we can construct a supermatrix model such that D=4 $\N=1$ super Yang-Mills theory can be derived from it. In addition, we can couple matter supermatrices to this supermatrix model and also construct models corresponding to $\N=2$ and $\N=4$ super Yang-Mills theories. In these investigations, we need to introduce a new non-anti-commutative superspace, and we investigate the definition of field theories on this space.Comment: 24 pages, published versio

Investigation of meson masses for real and imaginary chemical potential

We investigate chemical-potential ($\mu$) and temperature ($T$) dependence of scalar and pseudo-scalar meson masses for both real and imaginary $\mu$, using the Polyakov-loop extended Nambu--Jona-Lasinio (PNJL) model with three-flavor quarks. A three-flavor phase diagram is drawn in $\mu^2$-$T$ plane where positive (negative) $\mu^2$ corresponds to positive (imaginary) $\mu$. A critical surface is plotted as a function of light- and strange-quark current mass and $\mu^2$. We show that $\mu$-dependence of the six-quark Kobayashi-Maskawa-'t Hooft (KMT) determinant interaction originated in $U_\mathrm{A}(1)$ anomaly can be determined from lattice QCD data on $\eta'$ meson mass around $\mu =0$ and $\mu = i \pi T/3$ with $T$ slightly above the critical temperature at $\mu=0$ where the chiral symmetry is restored at $\mu=0$ but broken at $\mu =i \pi T/3$, if it is measured in future.Comment: 13 pages, 12 figure

Additive manufacturing for an extruder die plate using SUS316L water atomized powder

Gas atomized powder is commonly used for Laser powder bed fusion (L-PBF) additive manufacturing because of its good flowability. On the other hand, water atomized powder is inexpensive and has a great potential for application to middle range manufactured products. In this study, SUS316L water atomized powder was applied to L-PBF additive manufacturing. To solve its poor flowability and excessive spatter, we investigated these problems and modified the additive manufacturing machine. Our test results revealed that a laser energy density of 57.8 J/mm3 is one of the best laser conditions for water atomized powder additive manufacturing. To apply the design for additive manufacturing (DfAM), the mechanical properties and overhang process window were revised. Finally, an extruder die plate with better pellet productivity was designed and produced by using SUS316L water atomized powder. The results showed that, it produced better quality pellets than the original one. From this research, we found that water atomized powder is useful for L-PBF additive manufactured products