High Dynamic-Range and Very Low Noise K-Band p-HEMT LNA MMIC for LMDS and Satellite Communication

An excellent noise figure and high linearity, K-band p-HEMT LNA MMIC, that incorporates single-bias configuration and negative feedback circuit, has be en developed for LMDS (Local Multi-point Distribution Service) and satellite communication. The third order intercept point (IP3) of this MMIC is 20 dBm, while output power at 1-dB gain compression is 8.5 dBm. The IP3 and noise figure is 19.5 +/- 1 dBm and 1.8 +/- 0.2 dB, respectively, at frequencies between 24 and 32 GHz. The die size of the MMIC is 1.9 mm. This MMIC shows a potential reliable application in high-speed wireless access system

Interpolation between the epsilon and p regimes

We reconsider chiral perturbation theory in a finite volume and develop a new computational scheme which smoothly interpolates the conventional epsilon and p regimes. The counting rule is kept essentially the same as in the p expansion. The zero-momentum modes of Nambu-Goldstone bosons are, however, treated separately and partly integrated out to all orders as in the epsilon expansion. In this new scheme, the theory remains infra-red finite even in the chiral limit, while the chiral-logarithmic effects are kept present. We calculate the two-point function in the pseudoscalar channel and show that the correlator has a constant contribution in addition to the conventional hyperbolic cosine function of time t. This constant term rapidly disappears in the p regime but it is indispensable for a smooth convergence of the formula to the epsilon regime result. Our calculation is useful to precisely estimate the finite volume effects in lattice QCD simulations on the pion mass Mpi and kaon mass MK, as well as their decay constants Fpi and FK.Comment: 49 pages, 6 figures, minor corrections, references added, version to appear in PR

Prediction of impeller speed dependence of cavitation intensity in centrifugal pump using cavitating flow simulation with bubble flow model

We developed a numerical method of estimating not only cavitation erosion area but also cavitation intensity that depends on the impeller speed of pumps. Our numerical simulation code with a bubble flow model simulates the bubble pressure and the bubble nuclei distribution in a cavitating flow in detail. We simulated impulsive bubble pressure that varied within microseconds in a centrifugal pump. The cavitation intensity was estimated by analyzing the bubble pressure and the bubble nuclei distribution. The erosion area on the impeller blade in our pump test was visualized by using a method involving dye. The plastic deformation rate of an aluminum sheet attached in the erosion area was measured, and the cavitation intensity was estimated using an experimental database. The erosion area and cavitation intensity were measured at high and low impeller speeds. The erosion areas were both located on the suction side of the impeller blade, and they were distributed between the shroud and the mid-point of the blade near the leading edge. The measured cavitation intensity at high-speed was twice that at low-speed. The predicted areas of high cavitation intensity agreed well with the erosion areas in the experiment though the predicted areas slightly shifted to the leading edge. The predicted cavitation intensity at highspeed doubled that at low-speed as well as the experimental result. Therefore, we confirmed that the numerical method of estimating cavitation intensity was accurate. Next, we added three calculations while changing the impeller speed to obtain a function of cavitation intensity variations. The predicted function was a function of the impeller speed to the power, and this also corresponded to the experimental. Our code is thus effective for estimating the cavitation intensity that increases on the suction side of the impeller blade in a centrifugal pump when the impeller speed is changed.http://deepblue.lib.umich.edu/bitstream/2027.42/84313/1/CAV2009-final15.pd

Lattice study of meson correlators in the epsilon-regime of two-flavor QCD

We calculate mesonic two-point functions in the epsilon-regime of two-flavor QCD on the lattice with exact chiral symmetry. We use gauge configurations of size 16^3 32 at the lattice spacing a \sim 0.11 fm generated with dynamical overlap fermions. The sea quark mass is fixed at \sim 3 MeV and the valence quark mass is varied in the range 1-4 MeV, both of which are in the epsilon-regime. We find a good consistency with the expectations from the next-to-leading order calculation in the epsilon-expansion of (partially quenched) chiral perturbation theory. From a fit we obtain the pion decay constant F=87.3(5.6) MeV and the chiral condensate Sigma^{MS}=[239.8(4.0) MeV ]^3 up to next-to-next-to-leading order contributions.Comment: 20 pages, 12 figures, final version to appear in PR

Lagrangian Floer theory on compact toric manifolds I

The present authors introduced the notion of \emph{weakly unobstructed} Lagrangian submanifolds and constructed their \emph{potential function} $\mathfrak{PO}$ purely in terms of $A$-model data in [FOOO2]. In this paper, we carry out explicit calculations involving $\mathfrak{PO}$ on toric manifolds and study the relationship between this class of Lagrangian submanifolds with the earlier work of Givental [Gi1] which advocates that quantum cohomology ring is isomorphic to the Jacobian ring of a certain function, called the Landau-Ginzburg superpotential. Combining this study with the results from [FOOO2], we also apply the study to various examples to illustrate its implications to symplectic topology of Lagrangian fibers of toric manifolds. In particular we relate it to Hamiltonian displacement property of Lagrangian fibers and to Entov-Polterovich's symplectic quasi-states.Comment: 84 pages, submitted version ; more examples and new results added, exposition polished, minor typos corrected; v3) to appear in Duke Math.J., Example 10.19 modified, citations from the book [FOOO2,3] updated accoding to the final version of [FOOO3] to be publishe