Consequence Of Mass Conservation Research Articles

Low‐Density Cell of the Thermosphere at High Latitudes Revisited

AbstractThe density cell structure in the high‐latitude thermosphere is referred to as the density enhancement or depletion with respect to the surrounding area. Previous simulation results showed that the density cells are only observed below about 350 km. In the present work, the global ionosphere‐thermosphere model is used to investigate the mechanism for the absence of the isolated density cell in the high‐altitude thermosphere during geomagnetic quiet time. The simulation results indicate that the ion convection tends to drive a neutral cyclonic flow on the dawnside of the Magnetic Pole in both the low‐ and high‐altitude thermosphere. Around the center of the cyclonic flow, a downward wind is formed as a consequence of mass conservation. It is interesting that under the influence of the downward flow, a density depletion relative to the background density with the same magnitude is generated inside the cyclone, which is independent of altitude. In the low‐altitude thermosphere, this density depletion is shown as an isolated low‐density cell. However, in the high‐altitude thermosphere, the ion drag‐driven density depletion turns to be an insignificant structure, as compared to the strong day‐night gradient of the background neutral density. Consequently, the isolated low‐density cell does not stand out in the high‐altitude thermosphere.

Fundamental incorporation of the density change during melting of a confined phase change material

The modeling of thermal diffusion processes taking place in a phase change material presents a challenge when the dynamics of the phase transition is coupled to the mechanical properties of the container. Thermo-mechanical models have been developed by several authors, however, it will be shown that these models only explain the phase transition dynamics at low pressures when the density of each phase experiences negligible changes. In our proposal, a new energy-mass balance equation at the interface is derived and found to be a consequence of mass conservation. The density change experienced in each phase is predicted by the proposed formulation of the problem. Numerical and semi-analytical solutions to the proposed model are presented for an example on a high temperature phase change material. The solutions to the models presented by other authors are observed to be well-behaved close to the isobaric limit. However, compared to the results obtained from our model, the change in the fusion temperature, latent heat, and absolute pressure is found to be greatly overestimated by other proposals when the phase transition is studied close to the isochoric regime.

Constant mass model for the liquid-solid phase transition on a one-dimensional Stefan problem: Transient and steady state regimes

One way to study the dynamics of first order phase transitions is through solving the Stefan problem. The goal of this work is to develop a framework that allows researchers to predict the behaviour of a one-dimensional liquid-solid phase transition in the asymptotic time regime by taking into account volumetric effects through mass conservation. In most works on classical Stefan problems, only thermal diffusion in each phase and the variation of the heat flux through the interface by means of the Stefan condition are considered. In this paper, the model is generalized by considering mass conservation as well, which has not been reported before in the literature to the authors knowledge. By using a higher order finite difference scheme and the heat balance integral method for two different types of boundary conditions (isothermal and adiabatic), the improved model is solved.As a consequence of mass conservation, a subtle change in the thermal balance at the interface (Stefan's condition), is needed. The numerical and semi-analytical solutions for the improved model and the asymptotic values for the interface position, system length, temperature profile and liquid and solid masses, are compared. In the case of isothermal boundary conditions, due to mass conservation, more general asymptotic values are found. A good agreement between the numerical and semi-analytical solutions and the asymptotic time values is observed. In the case of adiabatic boundary conditions, the interface position at thermodynamic equilibrium can be overestimated by the numerical and semi-analytical solutions if only conservation of energy is considered. Finally, by applying mass conservation, a significant error decrease between the numerical and semi-analytical solutions and the predicted values at thermodynamic equilibrium is observed.

Particle trapping in stratified estuaries: consequences of mass conservation

Estuarine turbidity maxima (ETM) can retain suspended particulate matter (SPM) through advection, settling, aggregation, and nonlinearities in bed processes. We define a parameter space descriptive of ETM water column particle trapping processes through a scaling analysis of the local and integral SPM balances. There are six primary non-dimensional parameters for the large particles or aggregates that are typically trapped in an ETM. Rouse numberP, the ratio of settling velocityW S to the shear velocityU *, describes the material trapped in the ETM in terms of the local vertical balance between vertical mixing and aggregate settling. Advection numberA = PDU/UT scales the landward transport of SPM in terms of flood-ebb velocity difference (ΔU; the internal asymmetry) and maximum tidal current (U T ). Supply number Sr =PU r /U t defines SPM supply and removal (U r is river flow). Changes in the estuarine inventory of SPM are described in terms of a Trapping EfficiencyE, a ratio of peak ETM concentration to fluvial or marine supply concentration. The effects of aggregation and disaggregation in the integral dynamic balance are quantified by a Floc number Θ = Φ/Г that describes the balance of aggregation (Φ) and disaggregation (Г). The balance between erosion and deposition at the bed is described by the Erosion number Π = Ψ/Ω, the ratio of erosion (Ψ) to deposition(Ω). The non-dimensional, integral SPM conservation equation is then used to examine steady and unsteady particle trapping scenarios, including adjustments to a change in river flow and to a neap-spring transition in salinity intrusion and stratification.

Detailed balance in reaction kinetics — Consequence of mass conservation?

Detailed balance condition for triangular isomerisation mechanism is derived from the more general permanence of atoms, consequently, it should be viewed as a special equilibrium result of mass conservation.

Angular Momenta of the Antarctic and the Arctic Oscillations

Abstract The angular momentum anomalies associated with the Antarctic and Arctic Oscillations are examined in a coupled general circulation model. The size of the global-mean anomaly of the Ω angular momentum is unexpectedly larger than that of the relative angular momentum. The result is a simple consequence of mass conservation. Since the mass anomaly at high latitudes is equal and opposite to that at low latitudes, and since the high-latitude mass anomaly is relatively close to the rotation axis, the global-mean Ω angular momentum is significantly nonzero. Analysis of the meridional mass transport indicates that the Antarctic and Arctic Oscillations are persistent but damped modes.

Amanz Gresslyʼs role in founding modern stratigraphy

Research Article| December 01, 1997 Amanz Gressly's role in founding modern stratigraphy Timothy A. Cross; Timothy A. Cross 1Department of Geology and Geological Engineering, Colorado School of Mines, Golden, Colorado 80401 Search for other works by this author on: GSW Google Scholar Peter W. Homewood Peter W. Homewood 2Elf Exploration Production, 64018 Pau cedex, France Search for other works by this author on: GSW Google Scholar Author and Article Information Timothy A. Cross 1Department of Geology and Geological Engineering, Colorado School of Mines, Golden, Colorado 80401 Peter W. Homewood 2Elf Exploration Production, 64018 Pau cedex, France Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1997) 109 (12): 1617–1630. https://doi.org/10.1130/0016-7606(1997)109<1617:AGSRIF>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Timothy A. Cross, Peter W. Homewood; Amanz Gressly's role in founding modern stratigraphy. GSA Bulletin 1997;; 109 (12): 1617–1630. doi: https://doi.org/10.1130/0016-7606(1997)109<1617:AGSRIF>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract This paper discusses Amanz Gressly's (1814–1865) fundamental contributions to stratigraphy in three areas: facies concepts and applications, stratigraphic correlation, and paleogeographic reconstruction. To facilitate access to his discoveries, we present an English translation of his 1838 paper on facies and stratigraphic correlation. We discuss excerpts from this translation, which demonstrate that many of the fundamental principles of modern stratigraphy were understood and expressed by Gressly. We put this into the context of subsequent development and refinement of current stratigraphic principles.Gressly explained the genesis of sedimentary facies by processes operating in depositional environments. He demonstrated regular lateral facies transitions along beds, which he interpreted as mosaics of environments along depositional profiles. He recognized the coincidence of particular fossil morphologies with particular sedimentological facies, and distinguished “facies fossils” from those that had time value and that were useful for biostratigraphy (“index” or “zone” fossils). He discussed the equivalency of vertical facies successions through a series of strata and lateral facies transitions along a bed, developing the same principle that later became known as Walther's Law of the Correlation of Facies. He distinguished between the time value of strata and properties that reflect their genesis, and introduced specific terms to reflect this distinction. He used this understanding to show how stratigraphic successions should be correlated across different facies tracts.Gressly derived an internally consistent, logical, and comprehensive definition of a new stratigraphic paradigm, which was the basis for further developments and refinements. The five remaining principles of contemporary stratigraphic thought include: (1) the stratigraphic process-response system conserves mass; (2) sediment volumes are differentially partitioned into facies tracts within a space-time continuum as a consequence of mass conservation; (3) cycles of facies tract movements laterally (uphill and downhill) across the Earth's surface are directly linked to vertical facies successions, and are the basis for high-resolution correlation of stratigraphic cycles; (4) stratigraphic base level is the clock of geologic time, and the reference frame for relating the energy of space formation with the energy of sediment transfer; and (5) facies differentiation is a byproduct of sediment volume partitioning. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Theory of non-propagating surface-wave solitons

An incompressible inviscid fluid contained in a channel in a gravitational field admits soliton-like disturbances where the velocity potential depends upon all three coordinates as well as time, yet its centre of mass can be at rest. These solitons were recently discovered by Wu, Keolian &amp; Rudnick. The calculations are carried out with the multiple-scales approach. Consequences of mass conservation and radiation are discussed.

Differential chromatographic study of macromolecular changes governed by environmental factors.

GILBERT1 developed a differential gel chromatographic technique to compare the extents of association of two different haemoglobin species. This entailed the layering of a relatively large volume of solution of one species onto a column equilibrated with an identical concentration of the other. Differences in the weight-average elution volumes of the two solutes resulted in a change of protein concentration at the junction of the two solutions, this effect being a consequence of mass conservation. We wish to explore Gilbert's suggestion1 that the differential method could be adapted to study the effects of environmental factors (pH and ionic strength, I) on the state of a single solute system. The acid expansion of bovine serum albumin provides an example where a variation in pH induces a change in conformation and thus in elution volume. The effect of ionic strength on the extent of association of β-lactoglobulin A has also been studied, the change of weight-average elution volume in this instance being used to compare the association constants pertinent to two environments of different ionic strength.