Patrick Sebastian

Structuring of embodiment design problem based on the product lifecycle

Early stages of the design process are often based on designers experience; assumptions and irreversible decisions restricting the solution space are taken. It is difficult to take into account simultaneously every requirement imposed by the different phases of the product life-cycle. In this paper, a method is proposed to perform the analysis of the embodiment design problem. It facilitates the search of the indispensable elements, suitable for structuring the preliminary design phase. Our approach is performed for the relevant life-cycle situations of the product. A four level analysis (need, functions, organic structure and physical behaviours) is proposed. The set of structuring elements allow the design problem definition as a Constraint Satisfaction Problem (CSP).

Search heuristics for constraint-aided embodiment design

Abstract Embodiment design (ED) is an early phase of product development. ED problems consist of finding solution principles that satisfy product requirements such as physics behaviors and interactions between components. Constraint satisfaction techniques are useful to solve constraint-based models that are often partial, heterogeneous, and uncertain in ED. This paper proposes new constraint satisfaction techniques to tackle piecewise-defined physics phenomena or skill-based rules and multiple categories of variables arising in design applications. New search heuristics and a global piecewise constraint are introduced in the branch and prune framework. The capabilities of these techniques are illustrated with both academic and real-world problems. Complete models of the latter are presented.

Experiments and modeling of falling jet flash evaporators for vintage treatment

Flash evaporation of vintage is a challenging process that is used to cool grapes, to concentrate wine and to improve wine quality by increasing the extraction of polyphenol compounds from grapes. The development of this process encounters some difficulties in wine industry due to the low cooling efficiency of industrial systems. A mono-stage falling jet flash evaporator has been built and instrumented in order to observe the evolution of pressures, temperatures and flows inside the system. Experimental pilot scale tests have been carried out to investigate process performances using water or vintage as the fluid being treated. A network model of the steady-state behavior of the process is proposed and validated using the experiments. Simulation results of the process behavior focusing on thermodynamical aspects of vintage flash evaporator design are discussed. We mainly investigate the effects, of the condenser and the vacuum pump characteristics and of the pressure-drop inside the evaporator. The influence of the spray generated inside the separation chamber is also discussed. Technological improvements of the process actually implemented on a new experimental pilot are evoked.

Solving an air conditioning system problem in an embodiment design context using constraint satisfaction techniques

In this paper, the embodiment design of an air conditioning system (ACS) in an aircraft is investigated using interval constraint satisfaction techniques. The detailed ACS model is quite complex to solve, since it contains many coupled variables and many constraints corresponding to complex physics phenomena. Some new heuristics and notions based on embodiment design knowledge, are briefly introduced to undertake some embodiment design concepts and to obtain a more relevant and more efficient solving process than classical algorithms. n nThe benefits of using constraint programming in embodiment design are discussed and some difficulties for designers using CP tools are shortly detailed.

Design space exploration in embodiment design: an application to the design of aircraft air conditioners

The embodiment design of aeronautic systems proves to be a difficult design phase due to the variability in the system environment; the design is often constrained by atmospheric conditions. These atmospheric conditions appear to be highly variable according to the flight phases of the aircraft. The difficulty when designing air-conditioning systems for civil aircrafts is also inherent to the complexity of the coupling of the nonlinear physical phenomena inside of these systems (multi-physics, multi-scaling). Therefore, the design space appears to be very broad and quite difficult to explore. Embodiment design choices are relating to continuous and discrete design variables while the system effectiveness is extremely sensitive to most of these design variables. There is a lack of tools to support the investigation of the design exploration space and designer decisions at early stages of the design process. In this paper, a method is proposed to generate feasible embodiments and manage the compromise between various design requirements. A digital tool based on the meta-heuristic of Genetic Algorithms (Gas) has been developed to investigate the design problem. The selection of non-dominated solutions (Pareto) is used to identify relevant values for design variables and to facilitate choices among the design solutions of the air conditioning system.

Qualitative Constraints in Integrated Design

Designers use mechanical calculus and their technical knowledge to give, propose and validate technical choices. Product perception and design reasoning are modeled using graphs. The knowledge used is defined through fuzzy-logic rules, qualitative analysis, analytical forms and reasoning is represented as a system of constraints. We give an example which aims at defining the technological choices of a lattice work of beams.

Conception Inversée Intégrée : prédimensionnement de produits par satisfaction de contraintes

Mechanical design is based on aims of schedule of conditions. Design is an inverted integrated process: designers use aims to do design choices. This process, which requires a translation of all objectives, allows the synthesis of ideal dimensions (choices of materials, dimensions and shapes) from explicit and implicit rules. Rules translate all process laws and mechanical laws: mechanical calculus is integrated in design. Inverted Integrated Design (IID) process is modelized from a constraint based representation and a qualitative valuation. Constraints are analytical or are build from neural networks. Consistency techniques are used in CSPs to seek all consistent dimensions. We apply our work to the design of some pressure apparatus.

Modélisation de séchoirs à tapis. Utilisation des réseaux de neurones

Abstract Modelling of convective layer dryers. Using neural networks. Dryer modelling is considered in this paper. A dryer scale approach is implemented in order to write the classical differential equations through parameters such as the heat transfer coefficient or drying kinetics. The behaviour of the dryers is described by a non-linear system which integrates these equations in a transfer network using the finite difference method. The finite difference method is easy to implement, but appears to be too slow for dryer designing. So, in the second part of the study, neural networks are used to model drying process in steady state. When applying neural networks method to the design of dryers, one of the main problems is to find necessary and sufficient inputs so that the neural networks can learn transfers laws. To reduce the problem, each output is defined by a single neural network and non-dimensional numbers are used. The following step deals with the determination of the number of neurones and the minimization of output error for each efficiency (change of training points). Then, neural networks are used to simulate different configurations of dryers. Results are compared with the finite difference method and an industrial application is studied in the last chapter.