2023-12-04 PhyDiT provides the bare-essential classes and relationships which bridge to ontologies for control program description (like CTRLOnt, CDL etc.), system design description (like BRICK, SOSA, etc.), and physical process models (like OntoCAPE, Tubes, Flow etc.) https://github.com/autonomous-buildings/PhyDiT/blob/main/images/overview.png This ontology is distributed under a Creative Commons Attribution License - http://creativecommons.org/licenses/by/3.0 PhyDiT Ontology An ontology to enable creation of physics-inflused description of a digital twin. 1.1 Represents the physical influence of an actuator on a process variable which could be anywhere in the chain of process mechanisms. For example, when a valve actuator changes the opening in the flow path it influences the flow rate (immediat manipulation), but the influence of the changed flow rate may cause downstream or upstream effect - like changing the outlet temperature at a heat exchanger. The relationship between a process variable (and therefore of sensors and actuators that may be observing or manipulating) and a component which manages the process mechanism (to which the process variable is related) Refers to the physical stuff that process variable is specified for. For example, a variable "air flow rate" deals with "air" as the stuff. The engineering units used for measurement. This relation is used to model the situation that a PhysicalProcess is composed of one or more PhysicalMechanism. In this structural specification of a system, this relationship is used for specifying compositions (and aggregations). A Component may have one or more Ports through with stuff flows in or out. Used for indicating "where" a process variable can be observed or manipulated. The position is enumeration off well-known locations like inlet, outlet, bypass, etc. A control program has one or more interfaces to the outer world. Represents the immediate physical influence of an actuator on a process variable. A parameter (Parameter) of a control program can specify its source in the form of a DesignSpecification. For example, a control program might have a parameter which needs to be configured with the maximum input current of a component. A design specification (DesignSpecification) refers to a process variable. For example, the specification for "Maximum current drawn" refers to the electrical current (say, in Amperes) at the inlet terminal of a component. The specification also states the value (see hasMinValue, hasMaxValue, and hasNominalValue) A device that changes the characterstics of a mechanical form or electrical parameters such that stuff that flows through the conduit or conducting media is influenced in at least one physical variable. Examples include valve actuator which changes the opening in the flow path (thereby changing the pressure drop) and variable frequency drive of a motor which changes the characterstics of the AC waveform. An electro-mechanical device that from a given abstraction of the system design manages a physical mechanism. A software program that contains the control logic for operating the technical system A concept related to describing a control program. Specification of nominal, minimum, or maximum value of some physical process variable or sizing or characterstic of the technical system. Examples: minimum air flow rate, maximum current, tank capacity, etc. The interface through which a program obtains the state of the controlled process. The state could be a measured physical variable or a signal which could be potentially interesting to the program. The interface through with a program acts on the physical process. This is usually done by signaling an actuator. A value that is used or produced by the program for or by some intermediate computation. A component that does not play a direct role in the physical process but either observes a process variable it or actuates another component. PhySys (Pim Borst et al) defines this as "a specification of a generic physical principal or law". It covers "source, storage, dissipation, conversion, and distribution (of stuff in a process)". A practical take on this is for the automation application is that a mechanism is enaged in a distinct transformation of the state of a stuff (substance or energy). For example, in pump, the fluids static pressure is increased by transferring kinetic energy from the impeller. Examples include pressurization, combusion, heat transfer, throttling, etc. PhysicalProcess A physical process formed by a composition of mechanisms. The simplest process may have just one mechanism. A process is formed with an objective of tranforming one or more stuff by passing it through a chain of mechanisms. For example, dehumidification as a process may include first cooling the air below its dew point temperature and then reheating it. PhysicalMechanism, PhysicalStuff A concept that is used for describing the physical process and its physical mechanisms. Substance (matter) or energy which is involved in the physical process or mechanism. Examples include, air, water, heat, electrical current, etc. The physical connection point on a component through which stuff flows in or out. The position relative to a mechanism when we describe a process variable. This can be namely inlet or outlet. For example, we can say water temperature at inlet of the heat-exchange mechanism. The pyhsical variable that describes the state (quantity) of a stuff. The description of a variable therefore includes the stuff, quantity kind, and measurement units. The (software) interface of a control program The state or measurement of a (quantifiable) stuff. A device that uses a physical mechanism to measure a quantity and consequently produces a signal that is in a standard form to be an input to a controller hardware. The mechanism is implemented by a sensing element in the sensor. Additional electro-mechanical apparatus (more often electronics) interface with the sensing element to produce a standard signal form (e.g. 0-10V DC, 4-20mA, potential-free contact, etc.) A composition of components with a coherent set of process goals. A concept related to describing the structural design of a technical system. The unit of measurement for a quantity kind. The measured value (or quantity)