Recently Umemura, Fukue, & Mineshige (1997) proposed the radiative avalanche fueling to active galactic nuclei; gas accretion is driven by radiation drag exerted by stellar radiation from circumnuclear starburst regions. This mechanism is also interesting in terms of starburst-AGN connections. We therefore present observational tests for the radiative avalanche fueling. Our tests, however, show...

The standard theory of ideal gases ignores the interaction of the gas particles with the thermal radiation (photon gas) that fills the otherwise vacuum space between them. This is an unphysical feature of the theory since every material in this universe, and hence also the particles of a gas, absorbs and radiates thermal energy. The interaction with the thermal radiation that is contained withi...

The EGS4 electron-photon Monte Carlo code has been used to study the characteristics of the bremsstrahlung x-rays generated from the interaction of circulating electrons with the residual gas in accelerator storage rings. Gas bremsstrahlung dose rates are given for various opening angles as a function of the electron beam energy ranging from 0.510 GeV. Photon and neutron dose rates, generated f...

The hard X-radiation (20-200 keV) from Cyg X-3 shows a maximum at a phase 0.5 of the observed 4.8 hr modulation , while the soft X-radiation (2-12 keV) shows a maximum at a phase 0.75.Both the emissions show a minimum at a phase 0.0. This behaviour can be explained by considering the X-ray emission both by the compact object and the hot post shock gas left by the passage of the compact object t...

Black holes are most often detected by the radiation produced when they gravitationally pull in surrounding gas, in a process called accretion. The efficiency with which the hot gas radiates its thermal energy strongly influences the geometry and dynamics of the accretion flow. Both radiatively efficient thin disks and radiatively inefficient thick disks are observed. When the accreting gas get...

A heat transfer model has been developed that uses quasi-steady heat flux relations to calculate the heat transfer from combustion gases through the cylinder wall to the coolant in an internal combustion engine. The treatment of convective heat transfer accounts for the physical problems of rotating and impinging axial flow inside the engine cylinder. The radiative heat transfer includes gas ra...

Fired steam generators are the dominating technology of coal combustion in power plants. This paper presents a model for pulverized coal fired steam generators in Modelica. The model components are designed as an extension of SiemensPower, a Modelica library for transient simulation of power plants. The focus is on coal combustion, gas-particle-flow and radiation heat transfer in the furnace. T...

An attempt to detect the positronium Lyman alpha-radiation at 2430 A is reported. Positrons from an intense (64)Cu source (20 Ci) were stopped in high purity A, Ne, and He at pressures ranging from 0.01 to 3.0 atm. Light from the stopping region was collected by a large solid-angle light pipe and directed to a photomultiplier. Spectra were obtained by inserting a series of optical interference ...

We study the quantitative effects of excitation, ionization, radiation energy and pressure, on the jump conditions in hypersonic shocks in a real gas. The ionization structure and excitation energies are calculated from the local temperature and density, using the Screened Hydrogenic Model. We assume an optically thick medium and no radiation flux through the shock front. We investigate the jum...

Recent work on the transport of angular momentum in accretion disks suggests that the Velikhov-Chandrasekhar instability, in which a large scale magnetic field generates small scale eddys in a shearing environment, may be ultimately responsible for this process. Although there is considerable controversy about the origin and maintenance of this field in accretion disks, it turns out that it is ...