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In a Relation, PowerCalc can be used as if it were an intrinsic function like SIN(), SELECT() etc. as in the following example:
Power = PowerCalc(@Power, @Method:"Savitsky", @Speed:Vdes, L, B, T, D)
In this example PowerCalc represents the object (container) of a computational model that will compute Power on the basis of the values of Method="Savitsky", Speed=Vdes and the actual values of L, B, T and D. The @ character indicates that the parameter should exist in the PowerCalc object, the first parameter after the opening bracket (@Power) is the top goal of the PowerCalc object, @Speed:Vdes means that Speed in PowerCalc should get the value of Vdes. Values of L, B, T and D are required but not unique to this object and therefore requested as normal parameters and should be available "above" or outside the object. See also Quaestor syntax for more detail.
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The object PowerCalc created by evaluating the above relation is reusable and extensible: it is possible to request other goals from the same object instance, for example the rotation rateRevs:
N = PowerCalc(@Revs, @Method:"Savitsky", @Speed:Vdes, L, B, T, D)
If this relation is evaluated later than the earlier one, and Revs is not yet computed, Revs is added as top goal to the object after which the object attempts to add the necessary relations to its model and will compute its value.
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Relations should be available to compute Re on the basis of Length, Speed and Temp, as in Re=Speed*Length/Nu and Nu=f(Temp). This form of function definition will present theReynolds() function in the expression editor as if it were a Quaestor intrinsic function like SIN() or SELECT(). Any values or parameter can be used to fill in on the locations of Length, Speed and Temp, as in the following example:
RN75=Reynolds(C0_75,SQRT(V_a^2+(0.75*Pi*V_a/J)^2),CurTemp)
RN75 represents the Reynolds number of the propeller blade section at 0.75R in which: and
Length = C0_75
Speed = SQRT(V_a^2+(0.75*Pi*V_a/J)^2)and
Temp = CurTemp
Please note that the above could also be written in the first method as follows:
RN75 = Reynolds(@Re, @Length:C0_75, @Speed:SQRT(V_a^2+(0.75*Pi*V_a/J)^2), @Temp:CurTemp)
This example shows that the pseudo intrinsic way of defining functions is an elegant way to use Quaestor objects, in particular since the functions that are defined in this manner are presented in the Quaestor/Functions overview in the browser.
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By introducing the following list of relations in a new knowledge base, a miniature configurator is obtained:
Relation 1:
Ship(@Decks,@Bulkheads)
Relation 2:
Decks(@Deck)
Relation 3:
Deck(@Area, @ID$)
and put "@ASKORDER:Nr" in the data slot of Deck on a new line
Relation 4:
Bulkheads(@Bulkhead)
Relation 5:
Bulkhead(@Area, @ID$)
put"@ASKORDER:Nr"in putin the data slot of Bulkhead on a new line
Relation 6:
Area = L*B
put attribute put @LOCAL attribute in the data slots of L and B
Relation 7:
ID$ = CUROBJECT$(1)
Do not forget to provide the parameters dimensions in the Frame viewer, top right.
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Simply create a new knowledge base with the following relations:
QuadraticCurve(@Y,@X:"0(1)20")
Y = X^2
Couple the QuadraticCurve object to the relation Y = X^2 through the Constraint Connect menu option in the Knowledge browser:
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This makes that Y = X^2 is only valid within an instance of QuadraticCurve.
Enter the next relation:
Y = DQUAD(@QuadraticCurve, 2, @X, @Y, X)
Select Y as top goal and enter a value 3.5 for X. You will see that the QuadraticCurve object is created in the solution and you will get a result of 12.25.
Enter an additional relation that selects the third Y value from the QuadraticCurve object:
Y_3 = QuadraticCurve.Y.3
Select Y_3 as top goal will yield a result of 4.0.
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Introduce into an empty Quaestor the relations:
Y = DQUAD(@QuadraticCurve, 2, @X, @Y, X)
Y = X^2
Connect this relation to the QuadraticCurve object as is done above.
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Yet another way to create objects is illustrated by the following relations:
Z=QuadraticValue.Y
Y=X^2
Ask Z and give X=3 and you will get 9 as result. The QuadraticValue object in the solution contains the calculation with the Y=X^2 relation.
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