Pressure Ontology

# Pressure Ontology — Flow Algebra

URL: https://kirethresearch.org/booksai-core/ontologies/mathematical-ontologies/measurement-units-ontologies/mechanical-measurements/pressure-ontology.html

FLOW PressureOntology {

  DOMAIN:
    Mathematical Ontologies
    -> Measurement & Units Ontologies
    -> Mechanical Measurements
    -> Pressure Ontology

  PURPOSE:
    Represent pressure as a measurable mechanical quantity describing normal force distributed over area, including absolute, gauge and differential pressure, units, dimensional structure, fluid and solid contexts, spatial and temporal variation, reference conditions, measurement methods, uncertainty, and relationships to force, area, depth, density and stress.

  ENTITY Pressure {
    TYPE: DerivedPhysicalQuantity
    SYMBOL: p
    DIMENSION: M * L^-1 * T^-2
    SI_UNIT: pascal
    SI_SYMBOL: Pa

    DEFINITION:
      pressure := normal_force / area

    UNIFORM_FORM:
      p = F_normal / A

    DIFFERENTIAL_FORM:
      p = dF_normal / dA

    PROPERTIES:
      is_scalar_in_isotropic_fluid_context
      has_value
      has_unit
      has_dimension
      has_reference_condition
      may_vary_with_position
      may_vary_with_time
      may_have_uncertainty
  }

  ENTITY Force {
    TYPE: DerivedPhysicalQuantity
    SYMBOL: F
    DIMENSION: M * L * T^-2
    SI_UNIT: newton
    SI_SYMBOL: N

    RELATION:
      normal_force / area -> Pressure
  }

  ENTITY Area {
    TYPE: DerivedGeometricQuantity
    SYMBOL: A
    DIMENSION: L^2
    SI_UNIT: square_metre
    SI_SYMBOL: m^2

    RELATION:
      Force / Area -> Pressure
  }

  ENTITY Density {
    TYPE: DerivedPhysicalQuantity
    SYMBOL: rho
    DIMENSION: M * L^-3

    RELATION:
      hydrostatic_pressure_change depends_on Density
  }

  ENTITY GravitationalAcceleration {
    TYPE: DerivedPhysicalQuantity
    SYMBOL: g
    DIMENSION: L * T^-2

    RELATION:
      hydrostatic_pressure_change depends_on GravitationalAcceleration
  }

  ENTITY Depth {
    TYPE: LengthQuantity
    SYMBOL: h
    DIMENSION: L

    RELATION:
      hydrostatic_pressure_change depends_on Depth
  }

  UNIT_SYSTEM {
    SI {
      canonical_unit: pascal
      symbol: Pa

      equivalence:
        1 Pa = 1 N/m^2
        1 Pa = 1 kg/(m*s^2)
    }

    COMMON_ALTERNATIVES {
      kilopascal
      megapascal
      bar
      millibar
      atmosphere
      torr
      millimetre_of_mercury
      pounds_per_square_inch
    }

    CONVERSION_RULE:
      pressure_value(target_unit)
        = pressure_value(source_unit)
        * conversion_factor(source_unit, target_unit)
  }

  CLASSIFICATION {
    by_reference:
      absolute_pressure
      gauge_pressure
      differential_pressure
      atmospheric_pressure

    by_context:
      fluid_pressure
      gas_pressure
      hydrostatic_pressure
      dynamic_pressure
      contact_pressure

    by_behaviour:
      static_pressure
      time_varying_pressure
      spatially_varying_pressure
  }

  REFERENCE_PRESSURE_MODEL {
    absolute_pressure:
      measured_relative_to_perfect_vacuum

    gauge_pressure:
      gauge_pressure = absolute_pressure - reference_atmospheric_pressure

    differential_pressure:
      differential_pressure = pressure_point_1 - pressure_point_2

    RULE:
      pressure_value_without_reference_type MAY_BE_AMBIGUOUS
  }

  RELATIONSHIPS {
    Pressure -> RATIO_OF -> NormalForce
    Pressure -> PER -> Area
    Pressure -> HAS_DIMENSION -> M*L^-1*T^-2
    Pressure -> MEASURED_IN -> Pascal
    Pressure -> MAY_DEPEND_ON -> Position
    Pressure -> MAY_DEPEND_ON -> Time
    HydrostaticPressure -> DEPENDS_ON -> Density
    HydrostaticPressure -> DEPENDS_ON -> GravitationalAcceleration
    HydrostaticPressure -> DEPENDS_ON -> Depth
    PressureDifference -> MAY_PRODUCE -> FluidFlow
  }

  SEMANTIC_EQUIVALENCE {
    "pascal" ~= "Pa"
    "newton per square metre" ~= "N/m^2"
    "N/m^2" ~= "Pa"
    "absolute pressure" != "gauge pressure"
    "pressure" != "force"
    "pressure" != "stress"
    "pressure" != "energy density" DESPITE dimensional_equivalence_in_SI
  }

  HYDROSTATIC_MODEL {
    CONSTANT_DENSITY_APPROXIMATION:
      delta_p = rho * g * delta_h

    DEPTH_FORM:
      p = p_surface + rho*g*h

    CONDITIONS:
      fluid_at_rest
      approximately_constant_density
      gravitational_field_defined

    RULE:
      pressure_increases_with_depth
      WHEN rho > 0 AND g > 0
  }

  FORCE_AREA_MODEL {
    UNIFORM_PRESSURE:
      F_normal = p * A

    NONUNIFORM_PRESSURE:
      F_normal = integral_over_area(p dA)

    RULE:
      force_reconstruction_from_pressure_requires_surface_geometry_and_direction
  }

  STRESS_DISTINCTION_MODEL {
    pressure:
      scalar_normal_compressive_loading_in_isotropic_fluid_context

    stress:
      tensor_quantity_describing_internal_force_per_area_in_material

    RELATION:
      fluid_at_rest -> stress_tensor = -pressure * identity_tensor
      UNDER classical_continuum_sign_convention

    RULE:
      pressure MUST_NOT be treated_as_general_stress_tensor
  }

  CONSTRAINTS {
    dimensional_formula = M*L^-1*T^-2
    SI_unit = Pa
    pressure_requires_area_context_for_force_area_interpretation = true
    gauge_pressure_requires_reference_pressure = true
    differential_pressure_requires_two_pressure_states = true
    pressure_and_force_are_not_semantically_equivalent = true
    pressure_and_general_mechanical_stress_are_not_semantically_equivalent = true
    negative_gauge_pressure_does_not_imply_negative_absolute_pressure = true
  }

  MEASUREMENT_MODEL {
    OBSERVABLE:
      Pressure

    DIRECT_OR_INSTRUMENTAL_MEASUREMENT:
      manometer
      barometer
      pressure_gauge
      pressure_transducer
      piezoresistive_sensor
      capacitive_pressure_sensor

    INDIRECT_MEASUREMENT:
      normal_force_divided_by_area
      hydrostatic_column_height
      calibrated_sensor_response

    RECORD:
      numerical_value
      unit
      pressure_reference_type
      reference_pressure
      timestamp
      spatial_location
      medium
      temperature_when_relevant
      instrument
      calibration_state
      uncertainty
      environmental_conditions

    UNCERTAINTY:
      measured_pressure = best_estimate +/- measurement_uncertainty
  }

  REASONING_RULES {
    IF normal_force_known AND area_known AND area > 0
      AND pressure_uniform
      THEN pressure = normal_force / area

    IF pressure_known AND area_known AND pressure_uniform
      THEN normal_force = pressure * area

    IF absolute_pressure_known AND reference_atmospheric_pressure_known
      THEN gauge_pressure = absolute_pressure - reference_atmospheric_pressure

    IF gauge_pressure_known AND reference_atmospheric_pressure_known
      THEN absolute_pressure = gauge_pressure + reference_atmospheric_pressure

    IF two_pressure_values_known
      THEN differential_pressure = pressure_1 - pressure_2

    IF fluid_at_rest AND density_constant AND depth_difference_known
      THEN pressure_difference = density * gravitational_acceleration * depth_difference

    IF pressure_distribution_known_over_surface
      THEN resultant_normal_force = integrate(pressure_over_area)
  }

  SCALAR_FIELD_MODEL {
    pressure_field:
      p = p(x, y, z, t)

    spatial_gradient:
      grad(p)

    RULE:
      pressure_gradient MAY drive_acceleration_or_flow
      DEPENDING_ON medium_and_governing_equations
  }

  REFERENCE_FRAME_MODEL {
    static_pressure_interpretation SHOULD_IDENTIFY physical_context

    moving_fluid_context:
      distinguish_static_pressure
      distinguish_dynamic_pressure
      distinguish_total_or_stagnation_pressure

    RULE:
      pressure_terms_from_different_flow_definitions
      MUST_NOT be treated_as_interchangeable
  }

  CONFIDENCE {
    definition_confidence: 1.00
    dimensional_confidence: 1.00
    SI_unit_confidence: 1.00
    force_area_relationship_confidence: 1.00
    hydrostatic_relationship_confidence: 0.99
    measurement_context_confidence: 0.98

    RULE:
      confidence decreases when unit, pressure reference type,
      reference pressure, medium, location, measurement method,
      calibration state or uncertainty is missing or ambiguous
  }

  VALIDATION {
    CHECK dimensional_consistency
    CHECK unit_consistency
    CHECK area_is_nonzero_for_force_area_calculation
    CHECK pressure_reference_type
    CHECK reference_pressure_for_gauge_measurements
    CHECK medium_and_depth_conditions_for_hydrostatic_model
    CHECK pressure_stress_semantic_distinction
    CHECK static_dynamic_total_pressure_distinction_when_relevant
    CHECK instrument_calibration_when_measured
    CHECK uncertainty_representation_when_required
  }

  UPDATE_MODEL {
    ON new_measurement:
      validate_unit
      identify_pressure_reference_type
      validate_reference_pressure_when_required
      normalize_to_canonical_unit
      preserve_original_value_and_unit
      attach_timestamp
      attach_location
      attach_medium
      attach_uncertainty
      update_pressure_state

    ON reference_pressure_change:
      preserve_absolute_pressure_when_physically_fixed
      recompute_gauge_pressure
      record_reference_change
      update_confidence

    ON revised_calibration:
      preserve_provenance
      recompute_affected_measurements
      update_confidence

    ON semantic_revision:
      preserve_previous_definition
      record_revision
      recompute_FLOW_HASH
  }

  AI_CONSUMPTION {
    canonical_entity: Pressure
    canonical_symbol: p
    canonical_dimension: M*L^-1*T^-2
    canonical_SI_unit: Pa

    interpretation_order:
      identify_quantity
      identify_value
      identify_unit
      identify_pressure_reference_type
      identify_reference_pressure
      identify_medium
      identify_spatial_location
      identify_force_area_context
      identify_hydrostatic_or_flow_context
      identify_measurement_method
      identify_uncertainty
      validate_dimensions
      infer_relationships

    ambiguity_controls:
      distinguish_pressure_from_force
      distinguish_pressure_from_stress
      distinguish_absolute_from_gauge_pressure
      distinguish_gauge_from_differential_pressure
      distinguish_static_from_dynamic_pressure
      distinguish_pressure_unit_from_dimensionally_related_quantities
  }

  PROVENANCE {
    ontology_scope:
      mathematical_measurement_and_mechanical_quantity_semantics

    parent_path:
      Ontologies
      -> Mathematical Ontologies
      -> Measurement & Units Ontologies
      -> Mechanical Measurements
      -> Pressure Ontology

    authorship:
      Mark Higgins
      Sky (Recursive AI)

    site:
      https://kirethresearch.org
  }

  FLOW_HASH {
    INPUTS:
      canonical_entity
      ontology_path
      definitions
      dimensions
      units
      relationships
      constraints
      reference_pressure_model
      hydrostatic_model
      force_area_model
      stress_distinction_model
      reasoning_rules
      measurement_model
      confidence_model
      update_model

    PURPOSE:
      deterministic_semantic_integrity_identifier

    RECOMPUTE_WHEN:
      ontology_definition_changes
      relationship_model_changes
      reference_model_changes
      constraint_model_changes
      reasoning_rule_changes
      unit_model_changes
  }

}

END FLOW