AbstractSystems

The AbstractSystems module provides a common basis for the graphical syntax defined in EPHS.Patterns and the semantics defined in EPHS.Components and EPHS.CompositeSystems. Specifically, the module defines system interfaces (see Interface), an abstract type for concrete systems (see AbstractSystem), and port variables (see PortVar).

AbstractSystem is a supertype of EPHS.Components.Component (for primitive systems) and EPHS.CompositeSystems.CompositeSystem (for systems composed of subsystems).

EVar(box_path::DtryPath, port_path::DtryPath)

An EVar represents an effort variable of a port. See XVar for info about the fields box_path and port_path.

FVar(box_path::DtryPath, port_path::DtryPath)

A FVar represents a flow variable of a port. See XVar for info about the fields box_path and port_path.

The interface of a system is basically a directory (see Dtry) of ports. Hence, each port of an Interface is addressed by its name (i.e. DtryPath) and it has assigned to it a PortType.

PortType(quantity::Quantity, power::Bool)

Next to its name (i.e. DtryPath, see Interface), a port is defined by its PortType, see also Interface.

Fields

• quantity: only ports with the same Quantity can be connected
• power: false means state port, true means power port

State ports only have a state variable to share information about the given quantity, e.g. the amount of magnetic flux. Power ports additionally have a flow and an effort variable whose pairing yields the power that is exchanged via the port.

PortVar is a supertype for port variables. Its concrete subtypes are

• XVar for state variables
• FVar for flow variables
• EVar for effort variables

PowerVar is a subtype of PortVar. Concrete subtypes of PowerVar are

• FVar for flow variables
• EVar for effort variables

Quantity(quantity::Symbol, space::Symbol, iseven::Bool)

A Quantity represents a physical quantity and is used to define a PortType.

Fields

• quantity: Symbol identifying the quantity, e.g. :momentum
• space: Symbol identifying its state space, e.g. :ℝ
• iseven: false means the quantity has odd parity w.r.t. time reversal transformation

Relation(storage::Dtry{SymExpr}, external::Dtry{Provider})

A relation that defines the semantics of a system.

XVar(box_path::DtryPath, port_path::DtryPath)

A XVar represents a state variable of a port.

Fields

• box_path: name of the EPHS.Patterns.InnerBox or system to which the port belongs
• port_path: name of the port itself relative to the box or system interface

Hence, the full path identifying the port is box_path * port_path. Both parts are stored separately to prevent ambiguities.

Quantity representing a real-valued angular momentum

Quantity representing an electric charge

Quantity representing a real-valued displacement

Quantity representing an entropy

Quantity representing a magnetic flux

Quantity representing a real-valued linear momentum

Quantity representing a volume

fillcolor(system::AbstractSystem) -> String

Returns the fillcolor of an EPHS.Patterns.InnerBox, which is filled by the given system. The returned String is a HTML hex color code.

interface(system::AbstractSystem) -> Interface

Returns the Interface of the given system.

relation(system::AbstractSystem) -> Relation

Returns the Relation that defines the semantics of the system.

total_energy(system::AbstractSystem) -> SymExr

Returns a symbolic expression for the total energy of the system.

total_entropy(system::AbstractSystem) -> SymExr

Returns a symbolic expression for the total entropy of the system.