Electromagnetic power absorber

A structure is presented with a surface portion of dielectric material which passes electromagnetic radiation and with a portion below the surface which includes material that absorbs the radiation, the face of the structure being formed with numerous steep ridges. The steepness of the dielectric material results in a high proportion of the electromagnetic energy passing through the surface for absorption by the absorbing material under the surface. A backing of aluminum or other highly heat-conductive and reflective material lies under the face and has very steep protuberances supporting the absorbing and dielectric materials

Chiral Phase Transition in Lattice QCD with Wilson Quarks

The nature of the chiral phase transition in lattice QCD is studied for the cases of 2, 3 and 6 flavors with degenerate Wilson quarks, mainly on a lattice with the temporal direction extension $N_t=4$. We find that the chiral phase transition is continuous for the case of 2 flavors, while it is of first order for 3 and 6 flavors.Comment: uuencoded compressed tar file, LaTeX, 14 pages, 7 figure

QCD Phase Transition with Strange Quark in Wilson Formalism for Fermions

The nature of QCD phase transition is studied with massless up and down quarks and a light strange quark, using the Wilson formalism for quarks on a lattice with the temporal direction extension $N_t=4$. We find that the phase transition is first order in the cases of both about 150 MeV and 400 MeV for the strange quark mass. These results together with those for three degenerate quarks suggest that QCD phase transition in nature is first order.Comment: uuencoded compressed tar file, LaTeX, 13 pages, 9 figures, Minor errors for quoting references are corrected and a reference is adde

Finite Temperature Transitions in Lattice QCD with Wilson Quarks --- Chiral Transitions and the Influence of the Strange Quark ---

The nature of finite temperature transitions in lattice QCD with Wilson quarks is studied near the chiral limit for the cases of 2, 3, and 6 flavors of degenerate quarks ($N_F=2$, 3, and 6) and also for the case of massless up and down quarks and a light strange quark ($N_F=2+1$). Our simulations mainly performed on lattices with the temporal direction extension $N_t=4$ indicate that the finite temperature transition in the chiral limit (chiral transition) is continuous for $N_F=2$, while it is of first order for $N_F=3$ and 6. We find that the transition is of first order for the case of massless up and down quarks and the physical strange quark where we obtain a value of $m_\phi/m_\rho$ consistent with the physical value. We also discuss the phase structure at zero temperature as well as that at finite temperatures.Comment: uuencoded compressed tar file, 70 pages, 32 figure

Preliminary Centaur Systems Analysis

The Centaur is stored in the Orbiter payload bay on the Centaur Integrated Support System (CISS). The CISS not only cradles the Centaur prior to deployment but also provides any signal conditioning required to make the Centaur/Orbiter hardwire interfaces compatible. In addition, the CISS provides other Centaur functions such as controlling all the avionics safety features and providing all the helium supplies for tank pressurizations. Problems associated with a Centaur design concept using a transponder and two switchable antennas are defined. Solutions to these problems are presented

Phase structure of lattice QCD for general number of flavors

We investigate the phase structure of lattice QCD for the general number of flavors in the parameter space of gauge coupling constant and quark mass, employing the one-plaquette gauge action and the standard Wilson quark action. Performing a series of simulations for the number of flavors $N_F=6$--360 with degenerate-mass quarks, we find that when $N_F \ge 7$ there is a line of a bulk first order phase transition between the confined phase and a deconfined phase at a finite current quark mass in the strong coupling region and the intermediate coupling region. The massless quark line exists only in the deconfined phase. Based on these numerical results in the strong coupling limit and in the intermediate coupling region, we propose the following phase structure, depending on the number of flavors whose masses are less than $\Lambda_d$ which is the physical scale characterizing the phase transition in the weak coupling region: When $N_F \ge 17$, there is only a trivial IR fixed point and therefore the theory in the continuum limit is free. On the other hand, when $16 \ge N_F \ge 7$, there is a non-trivial IR fixed point and therefore the theory is non-trivial with anomalous dimensions, however, without quark confinement. Theories which satisfy both quark confinement and spontaneous chiral symmetry breaking in the continuum limit exist only for $N_F \le 6$.Comment: RevTeX, 20 pages, 43 PS figure

Hadron spectroscopy and static quark potential in full QCD: A comparison of improved actions on the CP-PACS

We present first results from a full QCD calculation on the CP-PACS, comparing various actions at $a^{-1} \sim 1 GeV$ and $m_\pi/m_\rho \approx 0.7$--0.9. We use the plaquette and a renormalization group improved action for the gluons, and the Wilson and the SW-Clover action for quarks. We find that significant improvements in the hadron spectrum results from improving the quarks, while the gluon improvement is required for a rotationally invariant static potential. An ongoing effort towards exploring the chiral limit in full QCD is described.Comment: 6 pages, based on talks presented by R. Burkhalter and T. Kaneko at Lattice97, Edinburg

Influence of PWM on the proximity loss in permanent magnet brushless AC machines

The winding copper loss can be significantly increased due to skin and proximity eddy current effects. The skin and proximity losses due to fundamental frequency current has been investigated in literature, but the influence of PWM on the skin and proximity losses has not been reported. In this paper, 2-D finite element method is employed to analyze the skin and proximity losses in a permanent magnet brushless AC machine, in which significant proximity loss exists due to high frequency current ripples induced by the PWM, as confirmed by both theoretical calculation and experiment. The analyses should be generally applicable to other machines

Equation of state in finite-temperature QCD with improved Wilson quarks

We study finite-temperature phase transition and equation of state for two-flavor QCD at $N_t=4$ using an RG-improved gauge action and a meanfield-improved clover quark action. The pressure is computed using the integral method. The O(4) scaling of chiral order parameter is also examined.Comment: LATTICE99(finite temperature), 3 page

Full QCD simulation on CP-PACS

A status report is made of an on-going full QCD study on the CP-PACS aiming at a comparative analysis of the effects of improving gauge and quark actions on hadronic quantities and static quark potential. Simulations are made for four action combinations, the plaquette or an RG-improved action for gluons and the Wilson or SW-clover action for quarks, at $a^{-1} \approx 1.1$-1.3GeV and $m_\pi/m_\rho \approx 0.7$-0.9. Results demonstrate clearly that the clover term markedly reduces discretization errors for hadron spectrum, while adding six-link terms to the plaquette action leads to much better rotational symmetry in the potential. These results extend experience with quenched simulations to full QCD.Comment: Talk presented by K. Kanaya at the International Workshop on ``LATTICE QCD ON PARALLEL COMPUTERS'', 10-15 March 1997, Center for Computational Physics, University of Tsukub