# Glossary#

- AAO#
All At Once

- algorithm integrator#
A user class of the formulation engine that integrates mathematical algorithms such as an optimization algorithm, DOE method or surrogate model

- anaconda#
A python tool to create virtual environment and easily install precompiled packages, https://www.anaconda.com/distribution

- ANN#
Artificial Neural Network

- ANR#
Agence Nationale de la Recherche

- API#
Application Program Interface

- ASO#
Asymmetric Subspace Optimization

- ATC#
Analytical Target Cascading

- bi-level#
A type of MDO formulation which formulates multiple optimization problems

- BLISS#
Bi-Level Integrated System Synthesis,

- BLISS2000#
Bi-Level Integrated System Synthesis, BLISS variant from 2000 paper, using surrogate models

- BLISS98#
Bi-Level Integrated System Synthesis, original BLISS variant from 1998 paper using coupled derivatives

- CFD#
Computational Fluid Dynamics

- chain#
A process that executes a set of disciplines in a sequential way, where outputs of the previously executed disciplines are passed as inputs of the next ones

- CO#
Collaborative Optimization

- complex step#
A numerical method to approximate the derivative of a function, similarly to finite differences, but using complex perturbations

- constraint#
A function of the design variables that must be kept either null or negative in an optimization problem

- constraints#
All the functions of the design variables that must be kept either null or negative in an optimization problem

- COTS#
Commercial Off The Shelf

- coupling variables#
In an MDO scenario, variables that are both used as inputs of a discipline and outputs of another one, or the same discipline

- CSM#
Computational Structure Mechanics

- CSSO#
Concurrent Subspaces Optimization

- data flow#
The sequence of data creation by, and exchanges between disciplines in a process

- data-driven#
Characteristic of a workflow engine, for which processes are described through the data flow, and in which the work flow is deduced accordingly

- design document#
A document that describes the design of a program, responding to a Software Requirements Specification

- Design Of Experiments#
A sampling of a design space, or a generic method that produces samplings of design spaces

- design problem#
An engineering problem such that a shape has to be changed to match or improve criteria under constraints

- design space#
The mathematical set containing the design variables of an optimization problem

- design variables#
The unknowns of the optimization problem

- DFO#
Derivative-Free Optimization

- disciplinary design variables#
In an MDO scenario, a subset of the design variables that are inputs of only one discipline

- disciplinary expert#
A user class of the MDO platform that wraps disciplinary capabilities into disciplines and creates, tests or maintains disciplinary processes

- disciplinary optimization#
The most basic MDO formulation restricted to a single set of design variables and only suited for a weakly coupled problem

- discipline#
One program, or an arbitrary set of simulation software, that can be viewed as a mathematical multivalued function, taking inputs and producing outputs through its execution

- DOE#
Design Of Experiments

- DOE algorithm#
An algorithm that generates samples of the design space

- driver#
- EA#
Evolutionary Algorithm

- eWORMS#
eclipse Workflow Management System

- finite differences#
A numerical method to approximate the derivative of a function by small perturbations of the inputs

- fixed-point#
A family of numerical resolution methods based on an iterative sequence of execution of the type : A() -> B() -> C() -> ... -> A() -> B() -> C() until convergence

- FPO#
Future Projects Office

- GEMSEO#
Generic Engine for Multi-disciplinary Scenarios, Exploration and Optimization

- generic process#
A process that can be applied to any discipline or set of disciplines, such as Multi Disciplinary Analyses methods that solves the coupling variables of a set of disciplines

- gradient#
Total derivative of a function with respect to its variables

- gradient-based optimization#
A class of optimization algorithms that use the total derivatives of the objective function and constraints

- grammar#
A set of rules to be respected by a data set. Typically used to describe the inputs and outputs of a discipline

- HDF#
Hierarchical Data Format to save and structure files with huge data

- Hessian#
The matrix of second order partial derivatives of one output with respect to inputs

- HPC#
High Performance Computing

- HTML#
Hypertext Markup Language

- IDF#
Individual Discipline Feasible

- interface#
A set of functions and data from a software exposed to other software

- IRT#
Institut de Recherche Technologique Saint Exupéry

- jacobian#
The matrix of first order partial derivatives of outputs with respect to inputs

- job scheduler#
A program used to distribute tasks and allocate resources for tasks on HPC clusters

- JSON#
JavaScript Object Notation

- JSON schema#
A JSON description of JSON data, similar to XML schemas

- KKT#
Karun Kuhn Tucker

- LHS#
Latin Hypercube Sampling

- library wrapper#
A code that translates the existing API of a program, or a library, into a compatible one

- local design variables#
In an MDO scenario, a subset of the design variables that are inputs of only one discipline

- LOO#
Leave One Out

- LP#
Linear Programming

- LSF#
COTS jobs scheduler for HPC clusters

- MDA#
Multi-Disciplinary Analysis

- MDF#
Multi-Disciplinary Feasible

- MDO#
Multi-Disciplinary Design Optimization

- MDO architecture#
the software architecture that enables the programming and resolution of MDO design problems

- MDO formulation#
The mathematical strategy used to define the optimization problem(s) to be solved

- MDO formulations designer#
A user class of GEMSEO that creates, implements, tests or maintains MDO formulations

- MDO formulations engine#
A program that enables the implementation of MDO formulations

- MDO integrator#
A user class that uses disciplines and MDO formulations to create, test and maintain MDO scenarios

- MDO platform#
A set of programs integrated in a common framework, enabling the resolution of multidisciplinary engineering problems using numerical simulation and optimization

- MDO user#
A user class of the MDO platform that executes an MDO scenario to produce results

- MDOIS#
MDO of Independent Subspaces

- MMA#
Method of Moving Asymptotes

- Model Center#
COTS workflow engine developed by Phoenix Integration

- modular architecture#
A software architecture based on separated components, with a relative independence between them

- Monolithic#
A type of MDO formulation which formulates a single optimization problem

- Newton method#
A root finding method that uses successive linear approximations of the function of interest

- NLopt#
Non-Linear Optimization package, an open source library of optimization algorithms from MIT, http://ab-initio.mit.edu/nlopt

- Object Oriented Programming#
A programming paradigm based on objects, which are data structures as well as a structure for methods

- objective function#
The function to be minimized or maximized in an optimization problem

- OpenDACE#
Open Design and Analysis of Computer Experiments: a program developed by Airbus to standardize interfaces of optimization algorithms, DOE methods and surrogate models as well as the related problems to be solved

- operating condition#
An input parameter of a simulation program that defines a physical parameter in which the system operates. Typically the speed of a vehicle, or its altitude

- optimization algorithm#
An algorithm capable of solving optimization problems

- optimization history#
The database of values of the objective function, constraints and design variables obtained during an optimization

- optimization problem#
A mathematical problem consisting in finding a set of variables which minimizes or maximizes a mathematical function (possibly a set-valued map), while satisfying constraints on these variables or on arbitrary functions

- optimum#
Solution of an optimization problem: the design variables values at the minimum of the function, subject to the constraints

- PIDO#
Process Integration and Design Optimization

- pip#
The PyPA recommended tool for installing Python packages. https://pypi.python.org/pypi/pip

- process#
A series of executions and data exchanges, ie the workflow and the data flow.

- processes data#
The disciplines inputs and generated outputs during the execution of a process

- RBF#
Radial Basis Function

- root finding#
A family of numerical resolution methods that solves multivariate problems of the type R(x)=0

- run time#
In computer science, run time, runtime or execution time is the time during which a program is running (executing), in contrast to other program life cycle phases such as compile time, link time and load time

- SAND#
Simultaneous Analysis and Design

- SBO#
Surrogate Based Optimization

- scenario#
The translation of a design problem into an executable. When executed, a scenario generates a process

- Scilab#
An open-source alternative to Matlab

- SciPy#
Open Source Library of Scientific Tools, containing a library of optimization algorithms, https://scipy.org

- Secure Shell#
(SSH) an encrypted network protocol for accessing remote computers

- sequence diagram#
A UML diagram that shows objects execution sequence, such as the function calls and their arguments, and the execution order

- serialization#
Process of writing objects or data structures to disk or more generally, to formats that can be stored

The design variables that are shared by more than one discipline

- simulation software#
A program that simulates a part of the physics of a system, or contributes to the overall simulation of the system, such as a mesher

- SLM#
Simulation Life Cycle Management

- SLSQP#
Sequential Least Squares Quadratic Programming

- SOM#
Self Organizing Map

- SRS#
Software Requirements Specification

- SSBJ#
SuperSonic Business Jet

- surrogate model#
A mathematical model of another model. Typically used to substitute an expensive simulation-based model by an approximation whose cost of evaluation is lower, at the price of an initial sampling of the original model

- SWIG#
Simplified Wrapper and Interface Generator

- system design variables#
The design variables that are shared by more than one discipline, at the system level optimization problem in a bi level MDO scenario

- trade-off#
A study that aims at comparing different options in terms of design parameters, and analyse their impacts

- UML#
Unified Modeling Language

- weakly coupled problem#
A multidisciplinary problem where the coupling variables can be computed by a single execution chain

- work flow#
The execution sequence of the disciplines in a process

- workflow engine#
A program used to design, run and analyze processes

- workflow-driven#
Characteristic of a workflow engine, for which processes are described through the work flow, and in which the data flow is deduced accordingly

- WORMS#
Workflow Management System

- wrapper#
Here discipline wrappers. Standardized interface defining inputs, outputs and execution of a given simulation software.

- XDSM#
eXtended Design Structure Matrix

- XML#
Extensible Markup Language