Dynamical rate property

Dynamical rate property

A dynamical property that is the temporal differential of a dynamical state property.

Rate properties represent the FORCE DIFFERENTIAL or the RATE OF FLOW of material, charge, energy, or information across a boundary separating one physical entity from another via some pathway. Examples: 1) fluid flow rate through a tube or vessel (dimensions of volume/time) 2) charge flow rate of an electrical current through an ion channel or wire (dimensions of charge/time or current) 3) chemical flux through a reaction kinetic pathway (dimensions of amount/time typially moles/sec or concentration/time) 4) the force in a spring as applied by entities at either end and as transmitted through the length of the spring. Rate properties can be properly attributed to entities in two mathematically equivalent, but logically different, ways. 1) Representing the source/sink of a process where the rate properties are attributed to participants in a process. For example, a fluid flow process has a fluid-source entity and a fluid-sink entity so that the fluid rate is expressed as flow from source-to-sink. Similarly, mechanical process is due to forces exerted by "entity A" upon "entity B" . This kind of formulation asserts that the flow/force properties are so-called "cross properties" because they describe how energy is transmitted across a process in which entities participate. 2) Representong rates as "through" properties as attributes of a "mediator" that is an entity through which the process occurs. For a fluid flow process, the fluid flow rate is thus attributed to the flow conduit (or more properly, the lumen of the conduit) that mediates the source-to-sink flow. Or, in the case of the transmission of mechanical force, across the interface or boundary between two mechanical solid entities. These different approaches yield mathematically equivalent results yet their semantic-logical representations differ ways that is a burden for the reasoning required to detect and resolve their equivalence. In the "cross" representation, source/sink enities are represented as source/sink participants in a process. In the "through" representation, source/sink entities are represented as parts of an entity that "mediates" the process. The distinction between "through" and "cross" properties (variables in math models) is commonly used in engineerng analyses such the PhysSys ontology; see: 1. Borst, P., H. Akkermans, and J. Top: Engineering ontologies. Int. J. Human–Computer Studies 1997. 46:365-406. 2. Karnopp, D., D.L. Margolis, and R.C. Rosenberg, System dynamics: a unified approach. 2nd ed. A Wiley-Interscience Publication1990, New York: Wiley.

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