SiMCAD front end

In order to be able to replay all the important steps of this work, a front end has been devel-oped to be able to launch the corresponding scripts. The front end is able to launch various sub-process of the work from the calibration of the models on a given aircraft database to the robust optimisation process including specific illustration of propagation techniques. For each sub-process, some input variables are offered to the user for modification but the list is not exhaustive and any other variables can be added just by modifying the scripts. The aim of this paragraph is to briefly present the use of the SiMCAD front end also called abusively tool box (the words SiMCAD tool box referencing the internal modules of SiMCAD in other parts of this report).

The SiMCAD front end is accessible from a Batch file (’.bat’). This file can be launched from Windows(R) by a double click or from a Disk Operating System (DOS) session. After double clicking on the Batch file, the user can visualise the GUI of SiMCAD front end, presented in Figure A.1.

Several choices are proposed to the user as a list of tabs. To activate his choice, he just has to click on the corresponding tab. In the remainder of this section, we give examples on the steps to follow to carry out specifics studies such as a deterministic aicraft optimisation or a robust aircraft optimisation.

A.1.1 Deterministic Optimisation

To launch a deterministic aircraft optimisation, the user has to click on the tap ’deterministic studies’ then on ’Optimised Design’. Another window opens so that the user can enter its preferences on the requirements the aircraft should fulfil: the total number of passengers, the range, the Cruise Mach number, the reference altitude, the number of engines, the By Pass Ratio, the Wing Aspect Ratio, the Take-Off Field Length and finally the approach speed. The user can visualise the process running (see Figure A.3).

The result of the optimisation is presented to the user through three files: a Scilab file and a text file containing the description of the optimal aircraft configuration and a graphic representing the position of the solution regarding the active constraints.

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Figure A.1: SiMCAD Architecture A.1.2 Uncertainty

The tool box offers several tabs related to uncertainty management. The first tab is related to the Beta-Mystique (Figure A.5). The user has the possibility to display a graphical setting of the Beta-Mystique distribution. It can also launch basic operations with this distribution:

addition, subtraction, multiplication, division, power, log, and exponential. Figure A.6 presents the addition of two Beta-Mystique distributions.

Uncertainty propagation study can be executed with SiMCAD tool box. Two methods are proposed: the moment propagation method and the Monte Carlo method. The moment prop-agation method is accessible via the tab ’moment propprop-agation’ and the Monte Carlo method under the tab ’sampling propagation’. Based on these propagation methods, we have imple-mented the whole code sequence for the robustness study of some processes such as the Margin Setting Process (see Figure A.7).

A.1.3 Robust aircraft optimisation

To launch a robust aircraft optimisation, the user has to click on the tab ’CCP by sampling’

for Chance Constraint Programming. The user will be offered a list of control to carry out the robust optimisation from the generation of error sampling to the resolution of the optimisation.

He will just have to follow the different steps from the first tabs to the optimisation.

The user can launch the robust optimisation by using two strategies: the first one is to build two levels of surrogate models in order to approximate the feasibility probability and the second one is to use moment propagation method.

To launch the first strategy with the surrogate models, the user has to execute the following steps:

• generate the model error sampling,

• build the performance data,

Figure A.2: Deterministic optimisation

Figure A.3: Deterministic optimisation running

Figure A.4: Results of the deterministic optimisation

Figure A.5: Beta-Mystique distribution

Figure A.6: Addition of two Beta-Mystique distributions

Figure A.7: Robustness study of the Margin Setting Process with the moment propagation method

• build the surrogates models to approximate the aircraft performances,

• build the surrogates models to approximate the feasibility probabilities,

• launch the robust optimisation named ’CCP by MC’.

To launch the second strategy with the moment propagation, the user has to execute the following steps:

• generate the model error sampling,

• launch the robust optimisation named ’CCP by FOM’.

Whatever the strategy selected by the user, when clicking on the taps for the resolution of the optimisation, the user is asked to enter its preference on the value of the confident levelP₀, as in Figure A.8.

Figure A.8: Optimisation with Surrogate Models strategy

SiMCAD front end also proposes a tab to launch multi-objective optimisation. The currently proposed resolution used the two level of surrogate models to approximate the feasibility proba-bility and the Genetical Algorithm Non dominated Sorting Genetic Algorithm (NSGA). During the execution, the user can visualise the point into the parameter space and the evolution of the Pareto Front.

Figure A.9: Multi-Objective optimisation with Surrogate Models strategy and Genetical Algo-rithm NSGA