# 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 artrary 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://www.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