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Dimensions
and call it General
.Parameter name | Dimension | Determined by | Reference | In Class |
| [-] (none!) | VR: User only | Block coefficient | Dimensions |
| [t] | USR: User or System/equation | Displacement of vessel at design draft | Dimensions |
| [t/m^3] | VR: User only | Density of water | General |
| [m] | VR: User only | Design draft of ship | Dimensions |
| [m^3] | USR: User or System/equation | Hull volume at design draft | Dimensions |
Lpp
, Boa
, Cb
, Displacement
, Rho
, T_design
and Volume
from the Knowledge Browser into the entity Hydrostatics
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Incidentally, the parameters Displacement
and Volume
still have their red crosses because they are not completely defined. You will add relations for them in a minute.
Rho
, change the number of decimals places into 3 in the Properties window of parameter Rho
.Because their there will only be two possible values for parameter Rho
(1.025 or 1.000 [t/m3]), it is useful to create a dropdown box. This can be done by providing a special reference.
Rho
.Density of water. Select water type;
1.025<EQ>Saltwater
1.000<EQ>Freshwater
In the Hydrostatics
entity, calculations need to be performed based upon information from Main Dimensions
and some relation. In order to achieve this, you have to create so called entity-relations. The first entity-relation to create will be for parameter Boa
in entity Hydrostatics
: the value of Boa
in entity Hydrostatics
should be equal to the value of Boa
in entity Main Dimensions
.
...
Boa = ENTITY#(12).Boa
This means Boa
is equal to (will copy the value of) the Boa
of the entity with QEntityID = 12.
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Info |
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An entity relation is something special. If you have experience with creating Quaestor knowledge bases (see the Tutorials on Quaestor basics), you will know that normally, a relation will be visible in the Knowledge Browser. Entity relations however, will only show themselves by the yellow colour of their parameters and the relation can only be shown by pressing Ctrl+Mhave the 'dimension' Taxonomy instead of None in the Knowledge browser. |
Lpp
in entity Hydrostatics
in the same way. This parameter must be equal to the value of Lpp
in Entity Main Dimensions
:Lpp = ENTITY#(12).Lpp
Finally, relations must be provided to calculate Displacement
and Volume
in entity Hydrostatics
. The following calculations should be made:
Displacement = Cb * Lpp * Boa * T_design * Rho
Volume = Cb * Lpp * Boa * T_design
Volume
in the same way. Delete ENTITY#()
in the editor and enter the expression above....
By adding the relation to the Knowledge Browser, you can connect it several times to various parameters in various entities, saving a lot of time.
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To connect the relation, in the Workbase, select the parameter Displacement
in entity Hydrostatics
. Then, select the right mouse button menu Taxonomy>Choose/create relation or relation or press Ctrl+T. A window will open showing the available relations for the selected parameter in the Knowledge Browser.
You can browse through the available relations and select the relation you want to use to compute the parameter, see Figure 67below. In this case select the relation you have just created. The same method can be used to include any available relation for any selected parameter.
Note that it is still possible to create a new taxonomy relation by selecting the first option in the popup window.
TODO: dit vind ik een erg onduidelijk stukje (ASR)
Perhaps you would like to have a bit Before we continue with the next Entity, we want to give more insight in the creation of relations in taxonomy type of knowledge bases. In the previous paragraph you have noticed that we created Entity-relations, paragraph 2.3.3.2 above and “normal” relations, paragraph 2.3.3.3 above. But why do we have two different methods?
You have three ways of adding and using relations:
Three important remarks can be made about the use of the different relation types:
Above you encountered two different methods of adding relations to entities. Why are there two different methods?
Note |
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Use the ENTITY# function only in combination with |
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entity relations |
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! You can use this function in normal relations but this is not advisable. |
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This is because the EntityID in the ENTITY# function will be renumbered when modifications are made to the |
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taxonomy that cause |
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entities to be renumbered. This renumbering |
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will not take place for normal relations. |
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