Constitutive property

A physics property whose value depends on the material composition and spatial properties of a physical process or process participant. The dependence of heat energy flow rate on values of a spatial gradient of temperature and a thlermal conductance of the material that composes the thermal flow pathway.

http://bhi.washington.edu/OPB#OPB_01502

A physics property whose value depends on the material composition and spatial properties of a physical process or process participant.

The dependence of heat energy flow rate on values of a spatial gradient of temperature and a thlermal conductance of the material that composes the thermal flow pathway.

Constitutive dynamical properties ultimately depend on an empirically determined material property (e.g., density, resistivity) of a participant in the process. For example, mass density depends on both the spatial distribution of atoms and the atomic weight of each. Resistance of a conductor depends on the resistivity of the material in the wire which is only defined and determinable empirically. There are two conflicting views of constitutive properties as properties of processes or of continuant entities: 1. The definition of constitutive property as a "ratio or partial derivative" of physical property values necessarily implicates a measurement process whereby values of two or more physical properties are varying and are measured and computed. However... 2. Constitutive properties are conventionally viewed as inherent attributes of a continuant or a process: . mass density is the ratio of a material amount to the extent of the spatial region that it occupies. . resistivity is the ratio of a potential difference to current flow rate for a an electrical flow process . 3) what is common to each case is that "constitutive properties" are defined in the context of a specific entity or process in a manner that depends on the material and structural composition of the entities participating in the measurement process. Any other algebraic form of the dependency may have specifially-defined parameters (e.g., offsets, rate parameters). Given the creativity and license of modelers for creating the best fit to constitutive dependencies, the parameters of such non-proportional dependencies must be annotated by some local mechanism that does not depend on OPB classifications. Constitutive proportionalities are approximations to dependencies for which a first-order, linear approximation is sufficient for the purposes of analysis. Piecewise linear approximations may apply over a limited range of dynamical property values. In general, various algebraic functions may be required using one or more parameters to fit observed dependency relationships. Given the range of possible constitutive dependencies, OPB defers representing such possibilities on a case-by-case basis for specific use-cases. Non-proportionality constants include coefficients and parameters required to characterize linear and nonlinear dependencies that are not simple proportionalities. Some may constitutive dependencies may include dynamic modeling schemes with internal dynamic states (e.g., the "gating variable" of Hodgkin-Huxley ion gating equations). We will treat such properties as "internal" to the constitutive dependency, shielded from other entities in the system and known solely as hypothetical constructs derived as constitutively observed dynamic phenomena. Thus, HH gating variables will be classified as properties of constitutive dependencies which are also subclasses of Dynamical property without, however, declaring a Dynamical entity of which it is a property. Important to realize that MM params, HH params, etc. are all derived and asserted by virtue of curve-fits to the directly observed attributes of a system; number of gating particles and their respective states is entirely inferential by best fits and, so, are no more physically real than any other coefficient or parameter.

Constitutive property

OPB:OPB_01502

Constitutive property

http://bhi.washington.edu/OPB#OPB_00147