Hydrostatic equilibrium

About: Hydrostatic equilibrium is a research topic. Over the lifetime, 2451 publications have been published within this topic receiving 62172 citations.

A Review of Models of the Solar Photosphere and Low Chromosphere: The Temperature-Height Profile

Abstract: The solar photosphere and low chromosphere may be defined as the regions of the solar atmosphere in which the temperature is less than 9000 K. The deeper photospheric layers with T > 9000 K are inaccessible to direct observation. The temperature rise through the chromosphere is probably severe above the height corresponding to T 9000 K and, therefore, this transition region between the chromosphere and corona is not discussed in this paper. Athay (I969) shows that the coronal pressure provides a strict boundary condition for a model chromosphere; the temperature T = 10000 K must be reached within 2000 km above the limb. The deepest observable layers are about 300 km below the surface. This paper is devoted to a discussion of models to represent these 2300 km of the solar atmosphere. A complete model would specify the magnitude and height variation of all significant variables; e.g. temperature, gas density, electron pressure, magnetic field and the velocity fields. The model would also include a representation of the spatial and temporal properties of the observable inhomogeneities, e.g. granulation, supergranulation and the chromospheric fine structures. The emphasis throughout this review is on empirical derivations of the temperature-height relation. Pure theoretical models are discussed briefly in ? 5. The Bilderberg continuum atmosphere (Gingerich & de Jager I968) is an empirical model which may be adopted as a convenient reference model against which the more recent observational and theoretical results may be set. The abbreviation B.c.a. is adopted. The majority of published measurements of the solar continuous spectrum have been obtained under conditions in which direct information on the fine scale structures is lost. Thus, the numerous empirical models in the literature were constructed as a representation of average conditions in the solar atmosphere. Direct observational studies of the fine scale features (e.g. granulation) are discussed in ? 6. An empirical model is based upon a set of near standard assumptions. The atmosphere is considered to be composed of homogeneous plane-parallel layers which are in hydrostatic equilibrium. It is widely supposed that a condition of local thermodynamic equilibrium (l.t.e.) exists throughout the atmosphere. These assumptions provide the fundamental integral equation relating the emergent continuous intensity IA(0, 0) to the temperature distribution TQrA) in the atmosphere

Physical Conditions in the Stellar Interior

Abstract: This chapter establishes the main equations of the stellar structure, namely, the continuity equation and the hydrostatic equilibrium equation, and gives some estimates of the average density, pressure, and temperature. Finally, a discussion is made of the thermodynamic equilibrium and the stellar energy.

Absorber-Replenisher in a Hydrostatic Circuit

Abstract: Methods and systems for operating an absorber-replenisher to supply fluid to a low pressure circuit in a hydrostatic circuit or recover surplus energy usually wasted across a pressure relief valve in the low pressure side by intensifying it for use in a high pressure circuit in the hydrostatic circuit. The absorber-replenisher 1) allows fluid flow through a high pressure motor-pump section of the absorber-replenisher from a high pressure circuit source causing a low pressure motor-pump section to turn providing additional fluid flow to the hydrostatic circuit, or 2) allows increased fluid flow from the low pressure portion of the hydrostatic circuit to increase pressure until the higher pressure induces a higher net torque of the low pressure motor-pump section to reverse the direction of the absorber-replenisher and pump fluid flow into a high pressure circuit through the high pressure motor-pump section.

Control of Hydrostatic Travel Drive System in Earth Moving Machines

Abstract: Aplication of hydrostatic travel drive system in tractor earth-moving machines enables a precise control of digging process according to given requirements and limits . A paper present some problems connected with this subject which have been chosen by the authors as the most important ones.