Phase transitions in filtration of Redlich-Kwong gases

In this paper we study a 3-dimensional filtration of real gases described by Redlich-Kwong equations of state. Thermodynamical states are considered as Legendrian (Lagrangian) submanifolds in contact (symplectic) space. Connection between singularities of their projection on the space of intensive variables and phase transitions is shown. Explicit formulae for the Dirichlet boundary problem are given and the distribution of phases in space is shown.Comment: 10 pages, 8 figure

Conservation equations and physical models for hypersonic air flows in thermal and chemical nonequilibrium

The conservation equations for simulating hypersonic flows in thermal and chemical nonequilibrium and details of the associated physical models are presented. These details include the curve fits used for defining thermodynamic properties of the 11 species air model, curve fits for collision cross sections, expressions for transport properties, the chemical kinetics models, and the vibrational and electronic energy relaxation models. The expressions are formulated in the context of either a two or three temperature model. Greater emphasis is placed on the two temperature model in which it is assumed that the translational and rotational energy models are in equilibrium at the translational temperature, T, and the vibrational, electronic, and electron translational energy modes are in equilibrium at the vibrational temperature, T sub v. The eigenvalues and eigenvectors associated with the Jacobian of the flux vector are also presented in order to accommodate the upwind based numerical solutions of the complete equation set

Stagnation-point heat-transfer rate predictions at aeroassist flight conditions

The results are presented for the stagnation-point heat-transfer rates used in the design process of the Aeroassist Flight Experiment (AFE) vehicle over its entire aeropass trajectory. The prediction methods used in this investigation demonstrate the application of computational fluid dynamics (CFD) techniques to a wide range of flight conditions and their usefulness in a design process. The heating rates were computed by a viscous-shock-layer (VSL) code at the lower altitudes and by a Navier-Stokes (N-S) code for the higher altitude cases. For both methods, finite-rate chemically reacting gas was considered, and a temperature-dependent wall-catalysis model was used. The wall temperature for each case was assumed to be radiative equilibrium temperature, based on total heating. The radiative heating was estimated by using a correlation equation. Wall slip was included in the N-S calculation method, and this method implicitly accounts for shock slip. The N-S/VSL combination of projection methods was established by comparison with the published benchmark flow-field code LAURA results at lower altitudes, and the direct simulation Monte Carlo results at higher altitude cases. To obtain the design heating rate over the entire forward face of the vehicle, a boundary-layer method (BLIMP code) that employs reacting chemistry and surface catalysis was used. The ratio of the VSL or N-S method prediction to that obtained from the boundary-layer method code at the stagnation point is used to define an adjustment factor, which accounts for the errors involved in using the boundary-layer method

2010 Annual Evidence Update on Critical Illness Rehabilitation

For this annual evidence update a detailed literature review was undertaken to retrieve any evidence published subsequent to the literature search which formed the basis for the NICE guideline. A total of 29 articles were selected for review and appraisal by a team of critical care practitioners. In this context it has to be noted that the evidence base on the subject is still relatively small. For the original guideline only 12 articles were selected as evidence which addressed the review questions. This evidence update intends to give an indication of encouraging trends within critical illness rehabilitation

Computer codes for the evaluation of thermodynamic properties, transport properties, and equilibrium constants of an 11-species air model

The computer codes developed provide data to 30000 K for the thermodynamic and transport properties of individual species and reaction rates for the prominent reactions occurring in an 11-species nonequilibrium air model. These properties and the reaction-rate data are computed through the use of curve-fit relations which are functions of temperature (and number density for the equilibrium constant). The curve fits were made using the most accurate data believed available. A detailed review and discussion of the sources and accuracy of the curve-fitted data used herein are given in NASA RP 1232

The Opportunity Cost of Electricity Outages and Privatization of Substations in Nepal

The unreliability of electricity supplies is a major cause of the high cost of manufacturing in developing countries. In this paper, we are able to measure the cost imposed by power outages and suggest some feasible mitigating measures. The study employs a rich, if not unique, set of data from three large manufacturing enterprises in Nepal. Using it, the opportunity costs to the enterprises from lost production from electricity outages can be estimated accurately. Power outages due to substation failure can be separated from other electricity systems failures. An analysis is carried out on the feasibility of privatized electricity substations. We find that this is a very worthwhile capital investment for the private sector to undertake, even when additional generation capacity to improve overall electricity reliability is not justified.electricity supply, reliability, opportunity costs, privatization