Snippets (text quotes and extracts from authoritative sources)

A Snippet is a short quote or extract (typically a phrase, a sentence, or at most a few sentences) from an authoritative source document such as a specification, technical manual, or design manual. Throughout this site, content is often related to supporting Snippets and each Snippet page links back to the content pages that reference it! The Snippet and Note concepts are very closely related and they support each other.

The Snippet concept is also at the heart of the Parsing Analysis recipe for UML® and SysML®

Kind Snippet quote/extract Source UML keywords SysML keywords Keywords
INFO In thermodynamics, heat is energy in transfer to or from a thermodynamic system, by mechanisms other than thermodynamic work or transfer of matter. Wikipedia heat, energy, energy transfer, thermal transfer, thermodynamics
INFO Some signals in the example reflect physical quantities, but this is not physical interaction in the sense of physical substances with flow rates and potentials ... SysPhS-1.1 SysPhS, humidifier, HVAC&R
INFO A.5 Humidifier: A.5.1 Introduction: This subannex gives a model of a room humidifier as an example of signal flows and state machines. SysPhS-1.1 SysPhS, humidifier, HVAC&R
INFO In many English-speaking countries, however, the most common shape of a handwritten Arabic digit 1 is just a vertical stroke; that is, it lacks the upstroke added in many other cultures. Wikipedia litre, units, scientific unit system, volume, SI unit, SI alternative unit, ISO-80000
INFO In 1990, the International Committee for Weights and Measures stated that it was too early to choose a single symbol for the litre. Wikipedia litre, units, scientific unit system, volume, SI unit, SI alternative unit, ISO-80000, United Kingdom, Ireland, Europe
INFO In the UK and Ireland, as well as the rest of Europe, lowercase l is used with prefixes, though whole litres are often written in full (so, "750 ml" on a wine bottle, but often "1 litre" on a juice carton). Wikipedia litre, units, scientific unit system, volume, SI unit, SI alternative unit, ISO-80000, United Kingdom, Ireland, Europe
INFO In these countries, the symbol L is also used with prefixes, as in mL and μL, instead of the traditional ml and μl used in Europe. Wikipedia litre, units, scientific unit system, volume, SI unit, SI alternative unit, ISO-80000, Canada, Australia, United States
INFO The United States National Institute of Standards and Technology now recommends the use of the uppercase letter L, a practice that is also widely followed in Canada and Australia. Wikipedia litre, units, scientific unit system, volume, SI unit, SI alternative unit, ISO-80000, Canada, Australia, United States
INFO Therefore, the digit "1" may easily be confused with the letter "l". In some computer typefaces, the two characters are barely distinguishable. As a result, L (uppercase letter L) was adopted by the CIPM as an alternative symbol for litre in 1979. Wikipedia litre, units, scientific unit system, volume, SI unit, SI alternative unit, ISO-80000
INFO Originally, the only symbol for the litre was l (lowercase letter L), following the SI convention that only those unit symbols that abbreviate the name of a person start with a capital letter. Wikipedia litre, units, scientific unit system, volume, SI unit, SI alternative unit, ISO-80000
INFO The litre (British English spelling) or liter (American English spelling) (SI symbols L and l, other symbol used: ℓ) is a metric unit of volume. It is equal to 1 cubic decimetre (dm^3), 1000 cubic centimetres (cm^3) or 0.001 cubic metre (m^3). Wikipedia litre, units, scientific unit system, volume
INFO The enthalpy of vaporization of Water at 100 deg C = 2257 (J/g) Wikipedia volumetric heat capacity, thermodynamics, joule, enthalpy of vaporisation, latent heat of vaporisation, heat of evaporation, enthalpy, evaporation
INFO The enthalpy of vaporization is often quoted for the normal boiling temperature of the substance. Wikipedia volumetric heat capacity, thermodynamics, joule, enthalpy of vaporisation, latent heat of vaporisation, heat of evaporation, enthalpy, evaporation
INFO The enthalpy of vaporization is a function of the pressure at which that transformation takes place. Wikipedia volumetric heat capacity, thermodynamics, joule, enthalpy of vaporisation, latent heat of vaporisation, heat of evaporation, enthalpy, evaporation
INFO The enthalpy of vaporization (symbol ∆Hvap), also known as the (latent) heat of vaporization or heat of evaporation, is the amount of energy (enthalpy) that must be added to a liquid substance to transform a quantity of that substance into a gas. Wikipedia volumetric heat capacity, thermodynamics, joule, enthalpy of vaporisation, latent heat of vaporisation, heat of evaporation, enthalpy, evaporation
INFO The volumetric heat capacity can also be expressed as the specific heat capacity (heat capacity per unit of mass, in J/K/kg) times the density of the substance (in kg/L, or g/mL). Wikipedia volumetric heat capacity, thermodynamics, joule, kelvin, water, celsius
INFO The SI unit of volumetric heat capacity is joule per kelvin per cubic meter, J/K/m3 or J/(K·m3). Wikipedia volumetric heat capacity, thermodynamics, joule, kelvin, water, celsius
INFO Informally, it is the amount of energy that must be added, in the form of heat, to one unit of volume of the material in order to cause an increase of one unit in its temperature. Wikipedia volumetric heat capacity, thermodynamics, joule, kelvin, water, celsius
INFO The volumetric heat capacity of a material is the heat capacity of a sample of the substance divided by the volume of the sample. Wikipedia volumetric heat capacity, thermodynamics, joule, kelvin, water, celsius
INFO Isobaric volumetric heat capacity C(P,v) J⋅cm−3⋅K−1 of liquid Water at 100 °C = 4.2160 Wikipedia volumetric heat capacity, thermodynamics, joule, kelvin, water, celsius
INFO Isobaric volumetric heat capacity C(P,v) J⋅cm−3⋅K−1 of liquid Water at 25 °C = 4.1796 Wikipedia volumetric heat capacity, thermodynamics, joule, kelvin, water, celsius
INFO The blocks used in these diagrams are introduced in Subannex A.5.4. SysPhS-1.1 SysPhS, humidifier, HVAC&R
INFO The internal structure of VaporGenerationPlant uses blocks Heating and Evaporation, which have internal structures depicted in Figure 70 and Figure 71, respectively. SysPhS-1.1 SysPhS, humidifier, HVAC&R
INFO The internal structure of Humidifier in Figure 68 uses a block VaporGenerationPlant, which has an internal structure shown in Figure 69. SysPhS-1.1 SysPhS, humidifier, HVAC&R
INFO The internal structure of HumidifiedRoom depicted in Figure 66 uses a block RelativeHumidity, which has an internal structure depicted in Figure 67. SysPhS-1.1 SysPhS, humidifier, HVAC&R
INFO The internal structure of the block HumidifierSystem shown in Figure 65 uses the blocks HumidifiedRoom and Humidifier. These two blocks have their own internal structures. SysPhS-1.1 SysPhS, humidifier, HVAC&R
INFO A.5.3 Internal structure: Figure 65 through Figure 71 show the internal structure of the total humidifier system and its components through seven nested internal block diagrams. SysPhS-1.1 SysPhS, humidifier, HVAC&R
INFO The humidifier uses information about the room’s humidity level to determine how much vapor to input to the room. The humidifier includes a water tank, a heater controller, and a vapor generation plant. SysPhS-1.1 SysPhS, humidifier, HVAC&R
INFO A.5.2 System being modeled: The total humidifier system has two main components: the humidified room and the humidifier, see Figure 64. SysPhS-1.1 SysPhS, humidifier, HVAC&R
NOTATION The compartment name is otherwise the same as it would appear on the type on a block definition diagram. OMG Systems Modeling Language (SysML) 1.6 compartment property compartment, SysML Internal Block Diagram, IBD :features compartments, :values compartment, :parts compartment, :properties compartment, :references compartment, :flow properties compartment, :operations compartment
NOTATION The label of any compartment shown on the property box that displays contents belonging to the type of the property is shown with a colon character (“:”) preceding the compartment label. OMG Systems Modeling Language (SysML) 1.6 compartment property compartment, SysML Internal Block Diagram, IBD :features compartments, :values compartment, :parts compartment, :properties compartment, :references compartment, :flow properties compartment, :operations compartment
INFO In nonideal fluid dynamics, the Hagen–Poiseuille equation ... is a physical law that gives the pressure drop in an incompressible and Newtonian fluid in laminar flow flowing through a long cylindrical pipe of constant cross section. Wikipedia Hagen–Poiseuille equation, fluid flow, hydraulics
INFO Figure 62 and Figure 63 show the parametric diagrams of the tank and the pipe, respectively. SysPhS-1.1 Constraint constraint parameter, ConstraintBlock, BindingConnector, SysML Parametric Diagram SysPhS
INFO Binding connectors link constraint parameters to simulation variables and constants, indicating their values must be the same. SysPhS-1.1 Constraint constraint parameter, ConstraintBlock, BindingConnector, SysML Parametric Diagram SysPhS
INFO Component parametric diagrams show properties typed by constraint blocks (constraint properties), as well as component and port simulation variables and constants. SysPhS-1.1 Constraint constraint parameter, ConstraintBlock, BindingConnector, SysML Parametric Diagram SysPhS
INFO Equations in constraint blocks are applied to components using binding connectors in component parametric diagrams. SysPhS-1.1 Constraint constraint parameter, ConstraintBlock, BindingConnector, SysML Parametric Diagram SysPhS
INFO Also, the fluid flow in the tank, fluidFlow, is related to the change in the fluid height level fluidHeight over time and the cross-sectional surface area of the tank, surfaceArea. SysPhS-1.1 Constraint constraint parameter, ConstraintBlock SysPhS, pressure, hydraulics, fluid flow
INFO The tank constraints specify that the pressure in the tank, pressure depends on the height of the fluid level in the tank, fluidHeight, as well as properties of the fluid, fluidDensity. SysPhS-1.1 Constraint constraint parameter, ConstraintBlock SysPhS, pressure, hydraulics, fluid flow
INFO The sum of the fluid flow rates going through the two pipe openings is zero (the fluid is assumed to be incompressible). SysPhS-1.1 Constraint constraint parameter, ConstraintBlock SysPhS, pressure, hydraulics, fluid flow
INFO The magnitude of fluid flow rate through the pipe fluidFlow is the same as the magnitude of flow rates opening1FluidFlow and opening2FluidFlow going through the pipe’s openings, though the values differ in sign. SysPhS-1.1 Constraint constraint parameter, ConstraintBlock SysPhS, pressure, hydraulics, fluid flow
INFO The fluid flow rate through the pipe, fluidFlow, is proportional to the pressure difference by the constant resistance, which depends on the geometric properties of the pipe as well as fluidic properties. SysPhS-1.1 Constraint constraint parameter, ConstraintBlock SysPhS, pressure, hydraulics, fluid flow
INFO The pipe constraints specify that the pressure pressureDiff across it is equal to the difference of fluid pressures opening1Pressure and opening2Pressure at each end of the pipe. SysPhS-1.1 Constraint constraint parameter, ConstraintBlock SysPhS, pressure, hydraulics, fluid flow
INFO In this example, constraint blocks PipeConstraint and TankConstraint define parameters and equations for pipes and tanks, respectively, as shown in Figure 61. SysPhS-1.1 Constraint constraint parameter, ConstraintBlock
INFO Equations define mathematical relationships between the values of numeric variables. Equations in SysML, are constraints in constraint blocks that use properties of the blocks (parameters) as variables. SysPhS-1.1 Constraint constraint parameter, ConstraintBlock
INFO An alternative for specifying initial values of part properties in the ConnectedTanks is to specialize it and redefine the part properties with default values for various configurations ... SysPhS-1.1 Property::redefinedProperty SysPhS
INFO SysML initial values specify property values for components used in internal block diagrams. Figure 59 shows initial values for fluid density, gravity, tank surface area, pipe radius, pipe length, and dynamic viscosity of the fluid ... SysPhS-1.1 initial values, context-specific values, initialValues compartment SysPhS, hydraulics
INFO Item flows on connectors indicate fluid passes through the ports and between the parts. The diagram connects a tank to each end of a pipe. SysPhS-1.1 Connector SysML Internal Block Diagram, ItemFlow SysPhS, hydraulics
INFO Part properties, typed by blocks ... represent components in this system. They are connected to each other through ports, which represent openings in the tanks and pipe ... SysPhS-1.1 Connector, Port part property, Block, "standard" Port SysPhS, hydraulics
INFO Figure 59 shows the internal structure of a ConnectedTanks block. SysPhS-1.1 SysML Internal Block Diagram SysPhS, hydraulics
INFO Each type of component has its own behaviors, defined as constraints ... SysPhS-1.1 Constraint ConstraintBlock SysPhS, hydraulics
INFO Tanks and pipes have openings for fluid to pass through, one for tanks and two for pipes. The openings are represented by ports of type VolumeFlowElement, from the physical interaction library .. SysPhS-1.1 SysPhS, hydraulics
INFO Figure 60 shows block definitions for components of ConnectedTanks in Figure 59. SysPhS-1.1 SysPhS, hydraulics
INFO A.4.1 Introduction: This subannex gives a model of a simple hydraulic system as an example of physical interaction (fluid flow). It does not include any signal flows SysPhS-1.1 SysPhS, hydraulics, fluid flow, physical interaction
INFO A.4.2 System being modeled: The hydraulic system has three components: two fluid reservoir tanks and a pipe for connecting these tanks, see Figure 58. SysPhS-1.1 SysPhS, hydraulics
INFO Figure 52 through Figure 57 show parametric diagrams for the source, amplifier, high-pass fil[t]er, low-pass filter, mixer, and sink, respectively. SysPhS-1.1 Constraint ConstraintBlock, constraint parameter, BindingConnector, SysML Parametric Diagram, constraint property, MD:ConstraintProperty SysPhS, signal processing
INFO Binding connectors link constraint parameters to simulation variables and constants, indicating their values must be the same. SysPhS-1.1 Constraint ConstraintBlock, constraint parameter, BindingConnector, SysML Parametric Diagram, constraint property, MD:ConstraintProperty SysPhS, signal processing
INFO Component parametric diagrams show properties typed by constraint blocks (constraint properties), as well as component and port simulation variables and constants. SysPhS-1.1 Constraint ConstraintBlock, constraint parameter, BindingConnector, SysML Parametric Diagram, constraint property, MD:ConstraintProperty SysPhS, signal processing
INFO Equations in constraint blocks are applied to components using binding connectors in component parametric diagrams. SysPhS-1.1 Constraint ConstraintBlock, constraint parameter, BindingConnector, SysML Parametric Diagram SysPhS, signal processing
INFO The source constraint specifies a sine wave signal with the parameter amp as its amplitude. The sink constraint displays (scopes) the output signal from the signal processor. SysPhS-1.1 Constraint ConstraintBlock, constraint parameter SysPhS, signal processing
INFO The mixer constraint specifies the relationship between its one output and the two inputs that come from the low-pass and high-pass filters. The constraint defines the output to be the average of the inputs. SysPhS-1.1 Constraint ConstraintBlock, constraint parameter SysPhS, signal processing, mixer
INFO The amplifier changes the signal strength by a factor gain, the low-pass filter eliminates the high-frequency components of the incoming signal, and the high-pass filter eliminates the low-frequency components of the signal. SysPhS-1.1 Constraint ConstraintBlock, constraint parameter SysPhS, signal processing, amplifier, high-pass filter, low-pass filter
INFO The amplifier, low-pass fil[t]er, and high-pass filter constraints show the input-output relationship of these components as the signal passes through them. SysPhS-1.1 Constraint ConstraintBlock, constraint parameter SysPhS, signal processing, amplifier, high-pass filter, low-pass filter
INFO In this example, a constraint block BinarySignalComponentConstraint defines the parameters for one input (ip) and one output (op), common to amplifiers, low-pass filters, and high-pass filters, as shown in Figure 51. SysPhS-1.1 Constraint ConstraintBlock, constraint parameter SysPhS, signal processing, amplifier, high-pass filter, low-pass filter
INFO Equations define mathematical relationships between the values of numeric variables. Equations in SysML, are constraints in constraint blocks that use properties of the blocks (parameters) as variables. SysPhS-1.1 Constraint ConstraintBlock, constraint parameter SysPhS, signal processing
INFO The xi and scope properties have the PhSVariable stereotype applied, specifying that their values might vary during simulation. SysPhS-1.1 value property SysPhS, signal processing, amplifier, high-pass filter, low-pass filter
INFO The amp, alpha and g properties have the PhSConstant stereotype applied, specifying that their values are constant during each simulation run. SysPhS-1.1 value property SysPhS, signal processing, amplifier, high-pass filter, low-pass filter
INFO The amplifier, filters (high-pass and low-pass), signal source, and signal sink have properties g, alpha and xi, amp, and scope, respectively. SysPhS-1.1 value property SysPhS, signal processing, amplifier, high-pass filter, low-pass filter
INFO This value type has no unit, reflecting that the signals are not measurements of physical quantities and do not follow conservation laws. SysPhS-1.1 Port Real, Unit, ValueType::unit, ValueType SysPhS, signal processing
INFO In this example, ports are typed by RealSignalOutElement and RealSignalInElement from the signal flow library ... which both have a flow property rSig typed by Real, from SysML, as shown in Figure 49. SysPhS-1.1 Port "standard" Port, FlowProperty, Real SysPhS, signal processing
INFO Signals flowing in and out of components are modeled by ports typed by interface blocks that have flow properties typed by numbers. SysPhS-1.1 Port "standard" Port, InterfaceBlock, FlowProperty, Number SysPhS, signal processing
INFO Each kind of component has its own behaviors, defined as constraints ... SysPhS-1.1 Constraint ConstraintBlock SysPhS, signal processing, mixer
INFO Signal flow is the movement of numbers between system components. These numbers might reflect physical quantities or not. In this example, they do not ... SysPhS-1.1 SysPhS, signal processing
INFO Mixers have inputs u1 and u2, and an output y. SysPhS-1.1 SysPhS, signal processing, mixer
INFO In Figure 50, amplifiers, low-pass filters, and high-pass filters, each have an input and an output. Since they are similar in this sense, a generalized TwoPinSignalComponent component has an input u and an output y. SysPhS-1.1 SysPhS, signal processing, amplifier, high-pass filter, low-pass filter
INFO The input for SignalSink is named u and is typed by RealSignalInElement, also from the library. The signal processor has an input and output, transforming the signal from the source and passing it to the sink. SysPhS-1.1 SysPhS, signal processing
INFO The output for SignalSource is named y and is typed by RealSignalOutElement, from the signal flow library ... SysPhS-1.1 SysPhS, signal processing
INFO Figure 49-Figure 50 show block definitions for components of TestBed and SignalProcessor in Figure 47 and Figure 48, respectively. SysPhS-1.1 Block SysPhS, signal processing, amplifier, filter, high-pass filter, low-pass filter
INFO Figure 47 shows an initial value for source amplitude amp, while Figure 48 shows initial values for amplifier signal gain g and filtering properties xi and alpha ... SysPhS-1.1 Property::defaultValue, Property initial values, context-specific values, initialValues compartment SysPhS, signal processing, amplifier, filter, high-pass filter, low-pass filter
INFO SysML initial values specify property values for components used in internal block diagrams. SysPhS-1.1 Property::defaultValue, Property initial values, context-specific values, initialValues compartment SysPhS, signal processing
INFO Figure 48 connects the signal processor input to an amplifier, the output of the amplifier to a high-pass filter in parallel with a low-pass filter, the outputs of the filters to a mixer, and the output of the mixer to the signal processor output. SysPhS-1.1 Port, Connector "standard" Port, SysML Internal Block Diagram SysPhS, signal processing
INFO Figure 47 connects a signal source to a signal processor, which it connects to a signal sink that displays the output. SysPhS-1.1 Port, Connector "standard" Port, SysML Internal Block Diagram SysPhS, signal processing
INFO Signals pass through ports in the direction shown by the arrows. Item flows on connectors indicate that the signals are real numbers. SysPhS-1.1 Port, Connector "standard" Port, FlowProperty, FlowProperty::direction, ItemFlow SysPhS, signal processing
INFO Part properties, typed by blocks ... represent the components of the system. They are connected through ports .. which represent signal outputs and inputs ... SysPhS-1.1 Port Block, part property, "standard" Port SysPhS, signal processing
INFO Figure 47 and Figure 48 show the internal structure of blocks TestBed and SignalProcessor, respectively SysPhS-1.1 SysML Internal Block Diagram SysPhS, signal processing
INFO A.3.2 System being modeled The signal processor and its testbed have a wave generator, an amplifier, high-pass and low-pass frequency filters, a mixer, and a signal sink, see Figure 46. SysPhS-1.1 SysPhS, signal processing, high-pass filter, low-pass filter, sine wave generator
INFO The source constraint defines the voltage across it as a sine wave with the parameter amp as its amplitude. SysPhS-1.1 Constraint constraint parameter, ConstraintBlock, Block SysPhS
INFO The source constraint defines the circuit’s electrical source. The ground constraint specifies that the voltage at the ground pin is zero. SysPhS-1.1 Constraint constraint parameter, ConstraintBlock, Block SysPhS
INFO The constraints for the resistor, capacitor, and inductor specify the voltage/current relationship with resistance, capacitance, and inductance, respectively. SysPhS-1.1 Constraint constraint parameter, ConstraintBlock, Block SysPhS
INFO The sum of the current going through the two pins adds up to zero (one is the negative of the other), because the components do not create, destroy, or store charge. SysPhS-1.1 Constraint constraint parameter, ConstraintBlock, Block SysPhS
INFO The current i through the component is equal to the current going through the positive pin. SysPhS-1.1 Constraint constraint parameter, ConstraintBlock, Block SysPhS
INFO These specify that the voltage v across the component is equal to the difference between the voltage at the positive and negative pins. The current i through the component is equal to the current going through the positive pin. SysPhS-1.1 Constraint constraint parameter, ConstraintBlock, Block SysPhS
INFO In this example, a constraint block BinaryElectricalComponentConstraint defines parameters and constraints common to resistors, inductors, capacitors, and sources, as shown in Figure 40. SysPhS-1.1 Constraint constraint parameter, ConstraintBlock, Block SysPhS
INFO Equations define mathematical relationships between the values of numeric variables. Equations in SysML, are constraints in constraint blocks that use properties of the blocks (parameters) as variables. SysPhS-1.1 Constraint constraint parameter, ConstraintBlock, Block SysPhS
INFO A.2.2 System being modeled: The electrical circuit has six components: ground, electrical source, inductor, capacitor, and two resistors, see Figure 37. SysPhS-1.1 SysPhS
INFO The block SpringMassSys has a SysML constraint property smsc typed by SMSConstraint. The constraint block has six parameters, each bound to a property reachable from the spring mass system: SysPhS-1.1 ConstraintBlock SysPhS
INFO Figure 25 shows an example [USAGE OF A] constraint block for a signal flow application, using ports like those defined in Figure 22, Subclause 10.7.3, except in a system containing a spring attached to another object. SysPhS-1.1 ConstraintBlock SysPhS
CONSTRAINT PhSVariable: [5] changeCycle must be positive or 0. SysPhS-1.1 SysPhS, SysML, Systems Modeling Language
CONSTRAINT PhSVariable: [4] changeCycle may be other than 0 only when isContinuous is false. SysPhS-1.1 SysPhS, SysML, Systems Modeling Language
CONSTRAINT PhSVariable: [3] isConserved may be true only when isContinuous is true and the stereotyped property is on a block specialized from ConservedQuantityKind (see Subclause 11.2.2). SysPhS-1.1 SysPhS, SysML, Systems Modeling Language
CONSTRAINT PhSVariable: [2] isContinuous may be true only when the stereotyped property is typed by Real or one of its specializations. SysPhS-1.1 Real SysPhS, SysML, Systems Modeling Language