19. List of physical quantities

19.1. The attribute physicalNature

In Amelet HDF data’s measure is given by the attribute physicalNature.

Permitted measures are reported in Summary of allowed measures.

19.2. SI unit

All quantities are expressed in SI unit to avoid lecture conversions except angles that are expressed in degree.

Warning

Angles are expressed in degrees.

19.3. Dealing with date

Globally, a date is a format to express the time. The Si unit for the time is the second and in this form it often defines a duration from a zero time. For computing dates, the zero time is the POSIX timestamp but a date can be a day far in the past with the following classical definition :

• year, the year can be negative

• month

• day

• hour in [0, 24] format.

• minute

• second

• microsecond

In Amlet-HDF a date is written is a string following this pattern :

year/month/day/hour/minute/second/microsecond/dayInTheWeek

The day in the week are :

• monday

• tuesday

• wednesday

• thirsday

• friday

• saturday

• sunday

Note

a “-” replaces not used elements.

Warning

A fictitious unit is introduced to write date : date

Example :

Sunday 16 November 2003 is written :

data.h5
`-- floatingType/
    `-- a_date[@floatingType=singleString
               @physicalNature=time
               @unit=date
               @value=2003/11/16/-/-/-/-/sunday]

or Wednesday 25 November 2009, 11:08:40 is written :

data.h5
`-- floatingType/
    `-- a_date[@floatingType=singleString
               @physicalNature=time
               @unit=date
               @value=2009/11/25/11/08/40/-/wednesday]

In addition, this format can be used in vector or arraySet like this :

data.h5
`-- floatingType/
    `-- pressure[@floatingType=arraySEt
        |        @physicalNature=pressure
        |        @unit=pascal
        |        @comment=the pressure]
        |        @unit=date]
        |-- data
        `-- ds
            `-- dim1[@floatingType=vector
                     @physicalNature=time
                     @unit=date
                     @label=day]

with date.h5:/floatingType/pressure/ds/dim1 is a string dataset containing :

2009/11/25/11/08/40/-/wednesday

2009/11/25/12/08/40/-/wednesday

2009/11/25/13/08/40/-/wednesday

19.4. component physicalNature

component physical nature is used in the definition of some ArraySet’s dimension. In the case where a dimension describes vector components like Ex, Ey, Ez Component parameter defines components stores in data.

The component physical nature has no unit.

Example of the components Ex, Ey, Ez of an electric field during the time :

data.h5/
`-- floatingType
    `-- dataOne[@floatingType=arraySet
        |       @label=Electric field around a wire]
        |-- data[@label=electric field
        |        @physicalNature=electricField
        |        @unit=voltPerMeter]
        `-- ds
            |-- dim1[@label=component x y z
            |        @physicalNature=component]
            `-- dim2[@label=the time
                     @physicalNature=time
                     @unit=second]

with data.h5:/floatingType/dataOne/ds/dim1 vector :

index	component
0	x
1	y
2	z

19.5. meshEntity physicalNature

meshEntity physical nature is used in the definition of Numerical data on mesh in the case where an ArraySet’s dimension corresponds to a mesh group. Mesh groups contain mesh entities.

The meshEntity physical nature has no unit.

Example :

data.h5/
|-- mesh/
|   `-- $gmesh1/
|       `-- $mesh1/
|           `-- group
|               `-- $efield_surface
`-- floatingType
    `-- $dataOne[@floatingType=arraySet
        |        @label=Electric field around the wire]
        |-- data[@label=electric field
        |        @physicalNature=electricField
        |        @unit=voltPerMeter]
        `-- ds
            |-- dim1[@label=component x y z
            |        @physicalNature=component]
            `-- dim2[@label=mesh elements
                     @physicalNature=meshEntity]

with /floatingType/$dataOne/ds/dim2 :

/mesh/$gmesh1/mesh1/group/$exchange_surface

19.6. electricPotentialPoint physicalNature

electricPotentialPoint is used in the definition of some ArraySet’s dimensions where the nature of the dimension corresponds to an electric potential point like :

• Multi-port ports

• Transmission line wires

• Thevenin generator

• Norton generator

The electricPotentialPoint physical nature has no unit.

19.7. Summary of allowed measures

Allowed values for the attribute physicalNature are reported in the following tabular :

Measure	Unit
admittance	siemens (S) / siemensPerMeter (S/m)
angle	degree (°)
angularVelocity	degreePerSecond (°/s)
capacitance	farad (F) / faradPerMeter (F/m)
component	no unit
conductance	siemens (S) / siemensPerMeter (S/m)
couplingCrossSection	squareMeter (m²)
directivity	no unit
efficiency	no unit
electricalConductivity	siemensPerMeter (S/m)
electricCharge	coulomb (C)
electricCurrent	ampere (A)
electricCurrentDensity	amperePerSquareMeter (A/m²)
electricField	voltPerMeter (V/m)
electricPotentialPoint	no unit
energyFluxDensity	wattPerSquareMeter (W/m²)
frequency	hertz (Hz)
gain	no unit
impedance	ohm (\(\Omega\)) / ohmPerMeter (\(\Omega\)/m)
inductance	henry (H) / henryPerMeter (H/m)
length	meter (m)
mass	kilogram (kg)
magneticConductivity	faradPerMeter (F/m)
magneticField	amperePerMeter (A/m)
meshEntity	no unit
permeability	henryPerMeter (H/m)
permittivity	faradPerMeter (F/m)
power	watt (W)
powerDensity	wattPerCubicMeter (W/m³)
propagationConstant	perMeter (1/m)
pressure	pascal (Pa)
radiationPattern	no unit
resistance	ohm (\(\Omega\)) / ohmPerMeter (\(\Omega\)/m)
surface	squareMeter (m²)
temperature	kelvin (K)
time	second (s) / date
volume	cubicMeter (m³)
voltage	volt (V)
volumetricMassDensity	kilogramPerCubicMeter(kg/m³)