A rigorous derivation of the stationary compressible Reynolds equation via the Navier-Stokes equations

We provide a rigorous derivation of the compressible Reynolds system as a singular limit of the compressible (barotropic) Navier-Stokes system on a thin domain. In particular, the existence of solutions to the Navier-Stokes system with non-homogeneous boundary conditions is shown that may be of independent interest. Our approach is based on new a priori bounds available for the pressure law of hard sphere type. Finally, uniqueness for the limit problem is established in the 1D case

Modern Developments in Engineering of Oxygen Steelmaking Shops for Bottom and Combined Blowing

The bottom blown basic oxygen steelmaking process was introduced and tested on low phosphorus hot metal in North America during 1971, The OBM/Q-BOP process proved to be an improvement over the top blown basic oxygen process in many aspects - capital costs, operating_costs, and process capabilities. Capital costs could be saved mainly because of much reduced Space requirements and deletion (particularly in the case of open hearth con-version) of extensive overhead material storage and han-dling systems due to the absence of lop lances and beca-use pneumatic material handling and bottom injection per-mitted replacement of gravity fed top additions. Operat-ing costs were reduced by a combination of high produc-tivity due to the capability of greater specific oxygen blowing rates and better product yields, both from charged-and additive materials

Complete BFT Embedding of Massive Theory with One- and Two-form Gauge Fields

We study the constraint structure of the topologically massive theory with one- and two-form fields in the framework of Batalin-Fradkin-Tyutin embedding procedure. Through this analysis we obtain a new type of Wess-Jumino action with novel symmetry, which is originated from the topological coupling term, as well as the St\"uckelberg action related to the explicit gauge breaking mass terms from the original theory.Comment: 22 pages, no figures, references adde

Five Dimensional Minimal Supergravities and Four Dimensional Complex Geometries

We discuss the relation between solutions admitting Killing spinors of minimal supergravities in five dimensions and four dimensional complex geometries. In the ungauged case (vanishing cosmological constant \Lambda=0) the solutions are determined in terms of a hyper-Kahler base space; in the gauged case (\Lambda<0) the complex geometry is Kahler; in the de Sitter case (\Lambda>0) the complex geometry is hyper-Kahler with torsion (HKT). In the latter case some details of the derivation are given. The method for constructing explicit solutions is discussed in each case.Comment: 8 pages. Contribution to the Proceedings of the Spanish Relativity Meeting 2008 in Salamanca, Spai

Roles of dark energy perturbations in the dynamical dark energy models: Can we ignore them?

We show the importance of properly including the perturbations of the dark energy component in the dynamical dark energy models based on a scalar field and modified gravity theories in order to meet with present and future observational precisions. Based on a simple scaling scalar field dark energy model, we show that observationally distinguishable substantial differences appear by ignoring the dark energy perturbation. By ignoring it the perturbed system of equations becomes inconsistent and deviations in (gauge-invariant) power spectra depend on the gauge choice.Comment: 5 pages, 4 figure

Infrared divergence of pure Einstein gravity contributions to cosmological density power spectrum

We probe the pure Einstein's gravity contributions to the second-order density power spectrum. In the small-scale, we discover that the Einstein's gravity contribution is negligibly small. This guarantees that Newton's gravity is sufficient to handle the baryon acoustic oscillation scale. In the large scale, however, we discover that the Einstein's gravity contribution to the second-order power spectrum dominates the linear-order power spectrum. Thus, pure Einstein gravity contribution appearing in the third-order perturbation leads to an infrared divergence in the power spectrum.Comment: Changed contents, to appear in Physical Review Letter

Mobile satellite service in the United States

Mobile satellite service (MSS) has been under development in the United States for more than two decades. The service will soon be provided on a commercial basis by a consortium of eight U.S. companies called the American Mobile Satellite Consortium (AMSC). AMSC will build a three-satellite MSS system that will offer superior performance, reliability and cost effectiveness for organizations requiring mobile communications across the U.S. The development and operation of MSS in North America is being coordinated with Telesat Canada and Mexico. AMSC expects NASA to provide launch services in exchange for capacity on the first AMSC satellite for MSAT-X activities and for government demonstrations

The AMSC mobile satellite system

The American Mobile Satellite Consortium (AMSC) Mobile Satellite Service (MSS) system is described. AMSC will use three multi-beam satellites to provide L-band MSS coverage to the United States, Canada and Mexico. The AMSC MSS system will have several noteworthy features, including a priority assignment processor that will ensure preemptive access to emergency services, a flexible SCPC channel scheme that will support a wide diversity of services, enlarged system capacity through frequency and orbit reuse, and high effective satellite transmitted power. Each AMSC satellite will make use of 14 MHz (bi-directional) of L-band spectrum. The Ku-band will be used for feeder links