Structural Analysis and Control of a Model of Two-site Electricity and Heat Supply

This paper introduces a control problem of regulation of energy flows in a two-site electricity and heat supply system, where two Combined Heat and Power (CHP) plants are interconnected via electricity and heat flows. The control problem is motivated by recent development of fast operation of CHP plants to provide ancillary services of power system on the order of tens of seconds to minutes. Due to the physical constraint that the responses of the heat subsystem are not necessary as fast as those of the electric subsystem, the target controlled state is not represented by any isolated equilibrium point, implying that stability of the system is lost in the long-term sense on the order of hours. In this paper, we first prove in the context of nonlinear control theory that the state-space model of the two-site system is non-minimum phase due to nonexistence of isolated equilibrium points of the associated zero dynamics.Instead, we locate a one-dimensional invariant manifold that represents the target controlled flows completely. Then, by utilizing a virtual output under which the state-space model becomes minimum phase, we synthesize a controller that achieves not only the regulation of energy flows in the short-term regime but also stabilization of an equilibrium point in the long-term regime. Effectiveness of the synthesized controller is established with numerical simulations with a practical set of model parameters

`Island Surfing' Mechanism of Electron Acceleration During Magnetic Reconnection

One of the key unresolved problems in the study of space plasmas is to explain the production of energetic electrons as magnetic field lines `reconnect' and release energy in a exposive manner. Recent observations suggest possible roles played by small scale magnetic islands in the reconnection region, but their precise roles and the exact mechanism of electron energization have remained unclear. Here we show that secondary islands generated in the reconnection region are indeed efficient electron accelerators. We found that, when electrons are trapped inside the islands, they are energized continuously by the reconnection electric field prevalent in the reconnection diffusion region. The size and the propagation speed of the secondary islands are similar to those of islands observed in the magnetotail containing energertic electrons.Comment: 5 pages, 4 figures, submitted to J. Geophys. Res

Mass singularity and confining property in QED3QED_3

We discuss the properties of the position space fermion propagator in three dimensional QED which has been found previouly based on Ward-Takahashi-identity for soft-photon emission vertex and spectral representation.There is a new type of mass singularity which governs the long distance behaviour.It leads the propagator vanish at large distance.This term corresponds to dynamical mass in position space.Our model shows confining property and dynamical mass generation for arbitrary coupling constant.Since we used dispersion retation in deriving spectral function there is a physical mass which sets a mass scale.For finite cut off we obtain the full propagator in the dispersion integral as a superposition of different massses.Low energy behaviour of the proagator is modified to decrease by position dependent mass.In the limit of zero infrared cut-off the propagator vanishes with a new kind of infrared behaviour.Comment: 22pages,4figures,revtex4,Notational sloppiness are crrected.Submitted to JHE

3D Measurement of Water and Bed Surface Shapes During the Formation of Sand Waves Using the Moving Optical Cutting Method

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchive

High statistics calculations of quenched QCD spectrum using various quark sources

We present the results for the hadron spectrum calculated on 400 configurations using point source, wall source and 8-cubic sources, in quenched QCD with Wilson fermions at $\beta=6.0$ and $K=0.155$ on a $24^3 \times 54$ lattice. The results for the ground state masses obtained with three types of quark sources agree well with each other. Masses of the first excited states appear consistent with experimental values within large errors.Comment: 3 pages, 2 postscript figures, to appear in the Proceedings of LATTICE 93, Dallas, USA; preprint UTHEP-26

First study on parasites of Hemibrycon surinamensis (Characidae), a host from the eastern Amazon region.

This study was the first investigation of communities and infracommunities of parasites of Hemibrycon surinamensis. All the fish collected in a tributary of the Amazon river were parasitized by one or more parasite species. The Brillouin diversity index (HB) was 0.46 ± 0.28 and the mean species richness was 3.5 ± 1.2 parasites per host. A total of 14,734 parasites were collected, including Ichthyophthirius multifiliis and Piscinoodinium pillulare (Protozoa); Jainus hexops and Tereancistrum sp. (Monogenoidea); Ergasilus turucuyus and Argulus sp. (Crustacea); metacercariae of Derogenidae gen. sp.; metacercariae and adults of Genarchella genarchella (Digenea); and Cucullanus larvae and Contracaecum larvae (Nematoda). The dominant parasite was I. multifiliis, followed by P. pillulare. The parasites showed aggregated dispersion, except for E. turucuyus, which had random dispersion. The condition factor (Kn) indicated that the parasitism levels had not affected host body condition. The high levels of infection observed were due to host behavior, and this was discussed. This was the first report of I. multifiliis, P. pillulare, Argulus sp., E. turucuyus, G. genarchella, J. hexops and Tereancistrum sp. in H. surinamensis, and it expanded the occurrence of E. turucuyus and G. genarchella to the eastern Amazon region

X-Ray Study of the Outer Region of Abell 2142 with Suzaku

We observed outer regions of a bright cluster of galaxies A2142 with Suzaku. Temperature and brightness structures were measured out to the virial radius ($r_{200}$) with good sensitivity. We confirmed the temperature drop from 9 keV around the cluster center to about 3.5 keV at $r_{200}$, with the density profile well approximated by the $\beta$ model with $\beta = 0.85$. Within 0.4\r_{200}, the entropy profile agrees with $r^{1.1}$, as predicted by the accretion shock model. The entropy slope becomes flatter in the outer region and negative around $r_{200}$. These features suggest that the intracluster medium in the outer region is out of thermal equilibrium. Since the relaxation timescale of electron-ion Coulomb collision is expected to be longer than the elapsed time after shock heating at $r_{200}$, one plausible reason of the low entropy is the low electron temperature compared to that of ions. Other possible explanations would be gas clumpiness, turbulence and bulk motions of ICM\@. We also searched for a warm-hot intergalactic medium around $r_{200}$ and set an upper limit on the oxygen line intensity. Assuming a line-of-sight depth of 2 Mpc and oxygen abundance of 0.1 solar, the upper limit of an overdensity is calculated to be 280 or 380, depending on the foreground assumption.Comment: 14 pages, 8 figure

Relativistic particle acceleration in developing Alfv\'{e}n turbulence

A new particle acceleration process in a developing Alfv\'{e}n turbulence in the course of successive parametric instabilities of a relativistic pair plasma is investigated by utilyzing one-dimensional electromagnetic full particle code. Coherent wave-particle interactions result in efficient particle acceleration leading to a power-law like energy distribution function. In the simulation high energy particles having large relativistic masses are preferentially accelerated as the turbulence spectrum evolves in time. Main acceleration mechanism is simultaneous relativistic resonance between a particle and two different waves. An analytical expression of maximum attainable energy in such wave-particle interactions is derived.Comment: 15 pages, 9 figures, 1 tabl