Fabrice Flipo

Energy: prometheus bound or unbound? A conceptual approach

Most c ontemporary debates surrounding tec hnologic al development refer to the myth of Prometheus, whic h tells of how Prometheus stole fire from the gods to give it to humankind. This fire, or energy, is the means through whic h human beings are able to exerc ise greater power over their environment…and over one another. The myth, as told by Plato, desc ribes how fire gave rise to hubris and c aused great wars between human beings. Henc e the two perspec tives adopted in the c ontemporary debate on tec hnology; some wish to see Prometheus ac t freely, thus allowing humanity to exerc ise the greatest powers possible over nature, and others would rather see Prometheus "c hained onc e again," judging that his power has bec ome too great. However, less well known is the c ontinuation of the myth: c haos impelled Zeus to send Hermes down to earth to bring dikè, justic e, bac k to humanity, thus re-establishing peac e. Indeed, the essential part of the myth is found in this often forgotten sec ond part and not in whether or not Prometheus should be freed or c hained. This artic le intends to draw from the lessons in this myth to analyz e the geopolitic s of c ontemporary energy. Following Ivan Illic h's analysis, it will be shown that moderation, or balanc e-as opposed to hubris, whic h desc ribes exc essiveness-is one of the nec essary c onditions underlying all global plans having peac e as their objec tive. At stake in the energy debate is none other than the question of the distribution of power. This means not only debating questions of aggregate ec onomic well-being but also legal questions (the right to development, the rights of future generations, etc .) La plupart des débats c ontemporains autour du développement tec hnique font référenc e au mythe de Prométhée. Prométhée a volé le feu pour le

donner aux hommes, et le feu, c 'est l'énergie, le moyen de démultiplier le pouvoir des hommes sur leur milieu… et sur leur proc hain. Le mythe, tel qu'il est rapporté par Platon, affirme en effet que le feu provoqua l'hubris et de grandes guerres c hez les hommes. D'où la polarisation du débat c ontemporain sur la tec hnique entre c eux qui veulent laisser Prométhée agir librement, de manière à c e que les Hommes disposent de pouvoirs aussi grands que possible pour agir sur la nature, et c eux qui voudraient plutôt " ré enc haîner " Prométhée, jugeant que son pouvoir est devenu trop grand. Ce que l'on c onnaît moins est la suite du mythe : le désordre c onduisit Zeus à envoyer Hermès pour remettre Dikè, la justic e, entre leurs mains, qui permit de ramener la paix. Nous montrons que l'essentiel du mythe est dans c ette sec onde partie souvent oubliée, et non autour de la question de savoir s'il faut libérer ou enc haîner Prométhée. Cet artic le entend tirer parti des leç ons de c e mythe pour analyser la géopolitique de l'énergie c ontemporaine. A la suite des analyses d'Ivan Illic h, nous entendons montrer que la sobriété, ou juste mesure, par opposition à l'hubris, l'illimité, est l'une des c onditions néc essaires de tout projet global ayant la paix pour objec tif. Ce qui est mis en jeu avec le débat sur l'énergie n'est autre que la question de la répartition du pouvoir. Cela suppose de mettre en débat non seulement des questions de bien-être éc onomique agrégé, mais aussi des questions de droit (droit au développement, droits des générations à venir etc .)

Index terms

Keywords : justic e, energy, philosophy, equity, geopolitic s, development Sections : Perspec tives Éditeur scientifique : Eric Duc hemin

Editor's notes

This paper is a revised version of an artic le originally published in Frenc h by VertigO-La revue électronique en sciences de l'environnement (Flipo, 2004a).

Full text

The lessons of Prometheus and Epimetheus

In terms of control, critics of technology often refer to readings of the ancient myth of Prometheus. What does this myth teach us (Plato) 1 ? He tells of how Epimetheus (literally meaning afterthought), the forgetful one, distributed gifts to all creatures, and because of this, had nothing left to give humankind. Prometheus, as his name suggests, was endowed with the gift of foresight; to make up for Epimetheus' omission and to give humankind a gift without which it would soon have perished, he stole fire and the arts, from Athena and Hephaestus. C onsequently, he is punished for this theft and is put in chains. The usual interpretations suggest that Prometheus' chaining allowed for the domestication of the arts and of fire and prevented Prometheus from endowing humankind with excessive powers that they would not have known how to control. Analyses often focus on these points, as if there were those who support the "re-chaining" of Prometheus on one side (Ministère de la Recherche: 2003), that is, giving the fire back to Hephaestus, stopping technical innovation and the risks it involves, and on the other, the supporters who, on the contrary, wish to see Prometheus remain unchained and count on the invisible hand or the materialism of history to harmonize everything and end up in a new era of abundance. In other words, the debate focuses on technical innovation to determine if the added power is good or not. Not surprisingly, it is around these same issues that discussions concerning the precautionary principle revolve [START_REF] Kourilsky | Le Princ ipe de Préc aution -Rapport au Premier Ministre[END_REF] This, however, seems to present a truncated version of the myth. Indeed, when confrontations surrounding the precautionary principle are expressed in those terms, they usually end up creating a dialogue of the deaf. Technology and action in general always entail a certain risk; the problem being specifically addressed here is not that one (Arendt, 1961). The ending of the myth, too often forgotten, puts a different perspective on the issue. In fact, it is said that Zeus sent Hermes to bring justice (dikè) and respect (aidôs), that is, the ability to develop an argument with respect to what is just so that technology can follow and so that conflict, excess (hubris), may be contained. Justice and respect are not technologies in themselves, but they embody the capacity to discern, to debate and to collectively implement the ends to which technologies must converge. Mastering technology is therefore less a question of whether or not extra power should be acquired than it is a question of who will benefit from this power. Therefore, the myth does not claim that releasing Prometheus would undermine the gods or nature. Neither does it maintain that appeasing Prometheus will necessarily lead to a levelling of values, as Nietzsche may have thought (Nietzsche, 1871). Rather, it asserts that hubris undermines justice and respect, that is, that which should be given to others. It questions who will benefit from this power, and if it is legitimate, that it should benefit the people identified. There is nothing exceptional about this. We therefore see to what extent the ancient Greeks were not taken in by technology-that is, by power.

2

There are three lessons to learn from this myth. The first is that human beings can be so fascinated by the immediate power technology provides, that they can forget about the consequences of these actions. And this has never been truer than it is today: we have succeeded in modifying the planet to an unprecedented extent, but we have no control over the consequences of the use of this power. Humanity has certainly become a geological force [START_REF] Vernadsky | The Biosphere[END_REF], but it is a force that is largely indiscriminate. This blind force is not solely the result of uncertainty about the action taken. For example, the hypothesis that climate change is a result of massive greenhouse gas emissions was put forward more than a century ago [START_REF] Arrhénius | On influenc e of c arbonic ac id in the air upon the temperature of the ground[END_REF]. This blindness is also a result of humanity, or at least a small part of it, only being interested in certain aspects of the world. For example, each year, the French newspaper Le Monde publishes a "state of the world" report, which is, in essence, devoted to the health of the economy and the technical innovations introduced by this economy. Surely the world represents much more than this! The state of less developed countries, the struggles for rights, the state of ecosystems and the planet, the current situation regarding equalities and inequalities and many other aspects are being ignored.

Industrialized societies are deeply involved in the race for power, but not for the control of this power. Improving conditions of well-being is no longer the criterion that guides most innovations, especially the most recent. Rather, it is the desire to succeed in doing what others have not succeeded in doing, or to see to it thata symbolic territory is taken from others, such as the "conquest" of space. The objective is to appear powerful and impress one's adversary. Miracle workers succeed in dazzling the masses and leaders and making them lose all touch with reality. GMOs and genetics are excellent examples of this. Although these technologies are closer to risky tinkering than to control, they are nonetheless regularly touted by firms and researchers as having unlikely miraculous merit, such as the eradication of hunger in the world or the control of the human species. These shortcuts, which could not for one minute withstand serious analysis, are positively mind-boggling. And yet, these speeches are given without restriction in public spaces through the very significant concept of "publicity"-in other words, of reference discourse for common sense (Arendt, 1961). The fact that the debate revolves around the potential range of miracles rather than around the underlying issues of power proves that it works to a large extent. The promoters of these ideas and those who receive them both believe them, or in any case, prefer to believe in them rather than seriously reflect on the issues and concern themselves with bringing some truth, or at least debate, into the public arena.

The second lesson to remember is that power is not shared by all just because the select few who hold it claim to put it at the service of all, or promise that it will be done in the near future. Therefore, to claim that humanity will one day colonize space is to forget the basic laws of physics and the present state of natural resources, which indicate that this can ever only be true for an extremely small minority of the earth's population, seeing that there might not be enough space in the biosphere for everyone to even have a moped. There are today 750 motorized vehicles for every 1000 people in the United States, compared to 8 in C hina and India (WRI, 2003) and these trends are also clearly incompatible with sustainable development (AIE, 2000). As it is well known, there is some danger involved in blindly delegating great power to a select few. This is as true in the field of technology as it is in other areas. This power can be used to subjugate others, in the present or in the future, human or not. The only way to ensure that control is maintained is to establish efficient structures that ensure participation and hold power in check. C ontrolling power involves nothing other than its democratization, to prevent it from being personified, embodied, or seized by a few people. The absence of participation in collective decisions-making processes that determine the daily entitlements of individuals can be referred to precisely as exclusion, whether it is energy-related, digital or other. Exclusion leads to division and to confrontation. The problem is much more evident on a global level: while all international negotiations are taking place as if economic growth and development were possible for the entire planet, it is already impossible, ecologically speaking, to generalize what has commonly been understood as development, that is to say, the way of life of industrialized or "developed" countries. Telling developing countries that they will never consume like industrialized countries is telling them that they are being excluded from globalization. After 50 years of promises, this represents a grave injustice with far-reaching geopolitical consequences.

The third lesson is that, contrary to what is claimed by Hans Jonas [START_REF] Jonas | The Imperative of Responsibility: In S earc h of Ethic s for the Tec hnologic al Age (trans. of Das Prinz ip Verantwortung[END_REF], the technological age is not only in need of ethics but also of justice, as the given problem cannot be solved on a personal level. Ethics specifically addresses individual behaviour, whereas justice concerns social order as a whole. Justice demands that what is due each person be respected, whether in the present, or the future, in the North or in the South. The traditional economic approach largely overlooks these issues. Its vision for the future does not extend beyond a decade, except for what comes in the guise of a promise of abundance, which it is not in a hurry to substantiate; and yet, signs of scarcity and the rise in inequalities-also being felt in industrialized countries-are on the increase The trend the scenario is said to present (IPC C , 2001)-describing economic growth as continuing indefinitely into the future-has not been questioned thoroughly enough. How can this trend be possible? What are the real consequences? What exactly does this growth entail? There are numerous inadequacies in the GNP indicator, particularly over the long term; it therefore seems questionable to view growth as always being a desirable objective. However, from an ecological perspective, the evidence is clear; economic growth has, up until now, been accompanied by increased pressure on the environment. If certain pressures have stabilized or have decreased slightly, it has been either because of the imports of natural goods or the creation of new pressures (Rees and Wackernagel, 1999;Bringezu et Schutz, 2001). What has been acknowledged as the geopolitical North depends to a great extent on the use of resources and environment that could have been of use to the South and to future generations. This use goes beyond usufruct rights, as was recognized by Lock, for example: "The same law of nature, that does by this means [that is, through work] give us property, does also bound that property too. God has given us all things richly. [...] As much as any one can make use of to any advantage of life before it spoils, so much he may by his labour fix a property in: whatever is beyond this, is more than his share, and belongs to others" (Locke: 1690). These "others" might, for example, include future generations if not non-human organisms of the natural world. To use a

The solution through growth famous expression, consumption beyond a certain point is theft [START_REF] Proudhon | Qu'est-c e que la propriété ? Paris[END_REF]. This not only calls into question individual behaviour, but also the moral and natural environment of societies, and their mores and physical infrastructures (urban planning, transportation, etc.) as well, so that our behaviour is not completely unrestricted, but rather directly predetermined by them. Indeed, it is difficult to avoid using the car in remote suburbs or resist the consumer pressure created by the enormous amounts of money spent on "publicity" (which is included in the price of the product, rendering it all the more expensive). In France, close to 50 billion euros 2 are invested in different communication costs, all having the same objective: to encourage consumption. The moral and physical infrastructures of the production-consumption society condition us and restrict us, suppressing any real form of protest representing anything other than a minor adjustment. The precaution, in this case, can be related to the pursuit of the same goals, with some "precautions" being ignored sooner or later, because striving for the same goals eventually leads to the continued celebration of the same social passions, which the law, unless it makes use of a great repressive force, cannot suppress.

Hubris, excess, the endless race towards power, was a danger well-known to the Greeks. For this reason, they made arêtê the tempering and balancing force, the supreme virtue of governance. The present system, however, runs contrary to this line of reasoning: instead of making temperance a central issue, it presents excess power and increased appropriation as a means to preventing truly political debates concerning the distribution of power from taking place. We are witnessing a generalized headlong flight. As long as average power increases over the short term and as long as growth brings more wealth, then everyone is happy and can expect more. Naturally, that is not altogether correct: power only increases on average.Even in "rich" countries, inequalities are on the increase. However, faith in growth is maintained, even among those who are excluded. An organization such as Attac, for example, does not call growth into question, only the distribution of its benefits. C oming back to Marx's conclusions, it suggests that the problem is that wage earners, and to a larger extent, the excluded, are poorly paid for the effort they make for the common good compared to owners or other classes benefiting from either being born into a more privileged class or from rules working in their favour. Ultimately, everyone hopes to become richer in the future, and this hope keeps the debate within narrow boundaries. This headlong flight is not only explained by the hope for increased well-being in the medium term in the context provided by the secularization of the world (Gauchet, 1985) or the rational principle of the perfectibility of the human species [START_REF] Ferry | L'espac e éc ologique -Fondements d'une théorie politique de la dimension naturelle de la liberté[END_REF]. The definition of progress as unlimited growth cannot be part of a rational political plan. As mentioned above, there is no reasoning that demonstrates that this objective is desirable over the long term. Nevertheless, the unlimited growth theory is presented as being a universal rationality, unaffected by the variability of cultures and opinions. It is presented as being an integral part of human nature, sheltered from historical contingencies, and as being a necessary and sufficient condition for progress. And when this does not occur, analysts are astonished. The following quote, taken from a United Nations report on global governance supports this: "We must accept the notion that progress is not only the work of destiny, but also the fruit of our labour" (C ommission on Global Governance, 1995). Analyses from the WTO rest upon the same notions: the automatic convergence of all towards happiness, without the need for politics. This is also seen at an individual level, as was observed by Alain Gras in his analysis of the creation of leading-edge technologies (Gras, 1994). More recently, Michèle Descolonges, an organizational sociologist, also made the same observation in an interesting comparison between the wide use of the Internet and the electrification of Russia in the 1920s (Descolonges, 2002). Progress is seen as part of destiny, a sort of natural law, existing as long as growth is maintained. Humanity is merely fulfilling its purpose in life. Faith in providence is nowhere more evident than when "we" speak of "our" species. This vision is not based on rationality, but rather, on a philosophy of history, on a perception of humanity's destiny that is based on a completely artificial construct of the world. Hegel is still relevant today, as are also Rostow and Marx. The great narratives are not obsolete. The concept of naturalism is deeply felt: our perception of humanity's destiny is shaped by the idea of a natural law that decides for "us" and absolves "us" of having to express truly political thoughts. If the future is predetermined, why discuss it? Should we not first continue to acquire powers that "we" can master? Should not mastery come of its own accord with time, led by the invisible hand, or more generally, by progress-in short, by Providence?

This vision presents problems such as nuclear pollution, (waste, explosions, etc.) or climate change as temporary or involuntary phenomena. They are seen as nothing more than "accidents" occurring along the way, as temporary malfunctions that will eventually disappear [START_REF] Virilio | Ce qui arrive[END_REF]. Nothing is seen as being irreversible, since the powers of humanity, which are expected to grow at a constant pace, will rebuild everything in the future. It is assumed that the substitution of technical capital for natural capital is infinite 3 . There is therefore no need for concern. None of the problems encountered should call into question the fundamental directions taken by human action, which must continue to be guided by the same objectives and rituals: increased production and consumption, the constant modification of nature, etc. This belief helps explain the slow building of awareness to the threat posed by climate change. In 1959, although the climate change hypothesis had been proposed more than 80 years prior, Alain Michel continued to maintain vehemently, in the monthly magazine Science & Vie,that there was "no

Taking on challenges or avoiding problems?

reason to worry": instead, trust should be placed in the powers of science to find the temperature controls of the planet before environmental disaster occurs (Michel, 1959). Alfred Sauvy's assertion in 1973 that sea levels could potentially rise by 70 metres did not elicit a stronger reaction; there was no reinforcement of research programs, and greenhouse gas emissions went unquestioned. Likewise, when supporters of nuclear power promise to soon eliminate the dangers posed by nuclear waste, they do not have to provide any proof; on the contrary, it is up to those who assert that danger is involved to prove their case.

The unlimited growth theory is therefore not based on a carefully thought-out, scientific or rational plan, but rather, it is based on a concept of nature and particularly, on a concept of human nature. It is based on a set of beliefs concerning the ultimate nature of the world that cannot be proven but nevertheless are taken to be true. They suggest that humans are homo faber and that their environment is similar to a stationary inexhaustible warehouse of materials put at their disposal. The resources and the environments are inexhaustible; that is, they can either be replaced one after the other or they are indeed exhaustible. If humanity continues to follow the standards brought to the fore by the economy, nature will be "restored" and we will live in abundance until the end of time.

Orthodox theories concerning the development of energy use through the pursuit of economic growth alone rest on these assumptions laden with meaning. This was recently seen in France: every debate on energy presupposes that the protagonists pledge their allegiance to this scope of thought, which leads to the concealment of a certain number of issues. 11 First, this externalizes most of the difficulties associated with energy use, under the pretext that they will "some day" be internalized. And yet, "we" are not the ones who will find the solution to the problems posed by nuclear waste and climate change, but our children. "We" will not have to answer to the demands made by countries of the South to consume as we do when natural goods [START_REF] Flipo | Les biens naturels[END_REF]) become very scarce. By stating that "we" will find solutions "in the future," we are giving ourselves the right to transfer the problem over to future generations. These issues should generate discussions and maybe even be put to referenda. The Declaration of the Rights of Man and C itizen, a preamble to the C onstitution of the Year I, stated that "A people has always the right to review, to reform, and to alter its constitution. One generation cannot subject to its law the future generations." Discussing humanity as if it were one subject when it is actually a multiplicity of subjects is therefore very dangerous. Added to this is the fact that the uses of nature may vary. Every culture maintains its own relationship with nature. It is not up to a given generation to make irreversible decisions concerning the nature of others. "We" are not future generations. Birth is the emergence of singularity, not only a continuation of self. Let us not take our desire for immortality as reality. Let us not fall into the trap so well known to psychoanalysts that has us wanting our children to be the continuation of our unfulfilled desires. We should remember the clear and simple lines of Khalil Gibran, which all of us have certainly encountered on our life's path: "Your children are not your children / They are the sons and daughters of Life's longing for itself / They come through you but not from you / And though they are with you yet they belong not to you." Nature belongs to us no more than our children do. It is a question of rights, not cost/benefits. To modify it irreversibly is to give ourselves the right to appropriate our children's future. This may be permissible, but only if we are certain that the modifications made are an improvement. And yet, nothing of the sort is taking place in either genetic engineering or with issues concerning climate change; in fact, quite the opposite is true.

Secondly, in the concept of nature as a warehouse, issues of scale and disruptions of natural regulation processes are never considered. Nature is always seen in Newtonian terms: linear and reversible. However, from an ecological perspective this is understood to be false: indeed, nature is a complex and fragile network of regulations, made up of distinctive areas each having their own characteristics and laws. C onsumption does not come out of nowhere: we create neither matter nor energy. We are simply modifying a dynamic and changing nature. Waste stays in the environment and takes on a life of its own. Although waste is seen, by the orthodox frame of thought, as confined to the area in which it was deposited, it nevertheless changes and has certain impacts. If it is biodegradable, then it does not pose a problem: it is reintegrated into the natural cycles of the environment of its own accord. If not, it disrupts natural regulatory functions, the results of which have been climate change, thinning of the ozone layer, etc. In a natural environment, certain changes are irreversible, that is, either definitively or for a very long period of time; these include death, climate changes, loss of biological diversity, areas contaminated by heavy metals or radionuclides, which have a lifespan of more than a million years, etc. This warehouse of materials presupposes that a set of regulations, human or not, is maintained: market conditions, standardized practices, stability of materials, etc. However, these regulations might not be maintained in the future. Indeed, there are numerous signs pointing in that direction. Political stability is not guaranteed, and we have begun to seriously affect the ecological balance. Petroleum, for example, currently plays an essential role in social regulations; however, there is every indication that the point at which it will become scarce is "approaching," 4 at least when considering the speed at which infrastructures are changing. How is it possible to survive in a city such as Los Angeles without energy for automobiles? Does avoiding chaos in Los Angeles not justify going to war to obtain the energy required to maintain the regulations that have been established for this purpose? The disruption of regulations creates an insecurity that first affects the most vulnerable and those who cannot pay for the services of a contrived protection.

Thirdly, inherent to the warehouse concept is the assumption that no natural assets have any intrinsic value: any worth can only come from human labour. Human-created processes are vehicles for the reorganization of the world according to "economic rationality." And yet, nature provides many assets: recycling of waste, soil regeneration, species turnover, etc. These assets have always been acknowledged everywhere up until the industrial era: usufruct became land annuity in the nineteenth century and slowly became reduced to nothing. Today, efforts are being made to assess, in economic terms, the contribution of nature to global well-being (C ostanza, 1997); and yet, it is clear that this aspect has been neglected and is still neglected today to a very large extent. Moreover, economic instruments developed to tally goods that are exchangeable on the market come to clearly unsatisfactory results. Natural regulations also provide a security that human-made regulations cannot provide. Humans can fail, betray, and behave as if they were stowaways. When contracts are no longer honoured, when payments can no longer be made, people reorganize themselves at lower levels of governance: this was clearly seen during Argentina's crisis and the collapse of the USSR. When people no longer have access to collectively produced goods, they have no other choice than to rely on local or even only personal goods. The protection of these natural assets, which are free and available everywhere, therefore provides a minimum guarantee of freedom. Of course, these assets are not equally distributed: land is not equally fertile everywhere. The biosphere is not Eden. Nevertheless, they are the primary source of wealth for human beings, particularly those considered to be poor in economic terms, that is, those who do not have any source of income. Forests have always catered to all the activists of the world. They are areas that elude social normalization and therefore the control of societies, even if they are totalitarian [START_REF] Roux | Géographie et c omplexité[END_REF]. Natural assets do not require a dependable political organization to be maintained, for nature takes care of that. They are often more sustainable than human-made assets and they are free. And yet, today, these regulations are threatened, even already deteriorated and damaged.

Fourthly, the dominant theory advances that all countries will converge towards the same "standard of living," that is, towards the social organization existing in industrialized countries today. And yet, we are not able to generalize our use of energy without causing damage that is far greater than the benefits obtained. The majority of the world's population uses very little energy, and what it does use is obtained mainly from biomass. Exported as raw materials, fossil fuels are becoming depleted and that at a price that does not reflect concern over distribution, for they are practically being sold at the price they were worth when extracted. Populations living by the extraction sites rarely benefit from this commerce. C ompanies involved in this business rarely pay any heed to the dictators that must be appeased to retain property rights, which is why the Ogoni have launched a battle against Shell in the Niger Delta. Most of the natural assets used today as resource or environment (waste) are low-entropy sources having the characteristics of finite stock (Georgescu-Roegen, 1979): their consumption is irreversible. Mines cannot produce more than the fossil deposits will allow. Only sustainable flows can regenerate. In addition, there is the iron law of diminishing returns: beyond a certain point, the energy expended to exploit the resource exceeds the energy produced by the resource. What resources will the world's poor use? The material consumption data are very clear: using growth as a solution for the social discord of the North and the transnational elite will erode future opportunities for generations to come and reduce the chances of the South seeing its living conditions improve. A miracle solution will not be available every time an internal distribution conflict in Europe must be resolved. Overload leads to congestion and congestion destabilizes the organization of the system as a whole. This is true for greenhouse gases as much as it is for automobile traffic. Avoiding the destabilization of systems entails regulation of access. The increase in power of some cannot be achieved without the decrease in power of others. The freedom of some must feed off the freedom of others. The global ecological space [START_REF] Ferry | L'espac e éc ologique -Fondements d'une théorie politique de la dimension naturelle de la liberté[END_REF] is no more infinite than is the space on a highway: choices must be made, and the choices being made at present are laden with consequences. Some fear the creation of a global apartheid or an ecological neo-colonialism [START_REF] Agarwal | Green Politic s[END_REF], in which an industrialized minority continues to use resources by preventing the rest of the world from consuming and in so doing, avoids having to call into question its way of life. C onsidering that the poor being referred to already have the atomic bomb (India, C hina), the future seems less radiant than the proponents of a conflict-free globalization would like to believe.

Energy: prometheus bound or unbound? A conceptua... http://sapiens.revues.org/index248.html

Conclusion: the path of moderation and the justice challenge

In the end, the problem is not so much to liberate or chain Prometheus as it is to stop believing in the myth of humanity as homo faber with its warehouse of materials affirming a predetermined future that will be glorious for all. This myth prevents us from seeing the real issues. Growth does not automatically lead to progress for everyone and the reasons for this have been known for a long time. As shown by Ivan Illich (Illich, 1973), they concern the materiality of the human condition, which is reaffirmed today in the ecological world view. The development that is taking place can only benefit a minority of the world's population; it is therefore urgent to rethink the energy issue in this context, rather than by sector or in a reductionist manner.

Energy is the fire that brings machines to life. Without it, there would be no armies of mechanical slaves or non-unionized workers working relentlessly, day after day, without complaining. There would remain only physical power and energy derived from the sun, wind, biomass, etc. There is no energy source that is clean, free or unlimited. They all give rise to some disadvantages that may be more or less serious or irreversible. Knowing who will be subjected to these disadvantages is as important as knowing who will benefit from the advantages, or if these advantages will increase at a given point in time. Machines are not necessarily useful: although they can reduce fatigue and suffering, they can also increase the production of weapons, become the source of destruction or be used to serve the interests of only a few. The real issue is to rethink the common good. It is clear that economic growth alone is leading us down the path to ruin. The trends described by trend scenarios are clear and support one another (WEC , 2000;UNPD, 2000). Unless various technological miracles are expected to occur-which, once again will be the responsibility of future generations-the world is headed for serious crises.

The issue is not the standard of living or comfort levels: numerous scenarios have shown that it is technically possible to attain a comfortable standard of living without compromising the well-being of others 5 . Places such as Sri Lanka or Kerala, in India, have attained very high levels of well-being while having a very minimal impact on the environment (cf. Figure 1). Mechanization no longer frees humanity from work. The effort expended today is for the most part devoted to the production of disposable objects or the creation of extra needs. This, in fact, has been the justification for putting human beings to work. We no longer have time for anything; everything moves too fast; we never stop running from one job to the next, never stop producing, consuming, filling out papers, etc. Other cultures have generally worked much less than ours, considering that their economic needs were met, as was shown by anthropologist Marshall Sahlins (Sahlins, 1976). Truly, the issue lies elsewhere. We must explore new avenues of cooperation founded on sharing and the recognition of others and not on exploitation and consumption. This leads to the questioning of the meaning of life for individuals and for communities: do we really need everything that we consume? Are we prepared to pay the price for our unrestrained over-consumption: police state, global apartheid, conflicts, ecological imbalances, etc.? Or do we want another world for ourselves? If that is the case, the creation of this other world starts with individuals: we must initiate the changes we would like to see take place in the world. Reducing our consumption means working less; it means taking part in the creation of a world that is more just and more united. As Gandhi once said, "There is enough on this earth to meet everyone's need but not everyone's greed."

The issue of needs must therefore be brought up once again, before the appetite of a few ends up devouring everyone else. This particularly involves raising questions about human nature. Yes, we must speak out forcefully against Bush and his consorts; justice requires that we assert that "our way of life is negotiable". This must be done to prevent globalization from turning into a bloodbath. Homo economicus, whohas an insatiable appetite, is a fiction who has become dangerous. Progress no Bibliography longer entails producing and consuming; it involves building sustainable societies that live in harmony with their natural environment. The means necessary to achieve this are stated in the triptych "moderation, energy efficiency and renewable energy" 6 and are at the service of justice. This is not a question of GDP points, but rather, an issue concerning civilization.

Figure 1 .

 1 Figure 1. Comparison of environmental performance in 49 nations.

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Keqin Wang
email: keqinwang@nwpu.edu.cn

Shurong Tong
email: stong@nwpu.edu.cn

Nada Matta
email: nada.matta@utt.fr

Lionel Roucoules
email: lionel.roucoules@ensam.eu

Benoît Eynard
email: benoit.eynard@utc.fr

Ontology Building of Manufacturing Quality Knowledge for Design Decision Support

Keywords: ontology building, manufacturing quality knowledge, design decision, design support, design ontology

Manufacturing knowledge on product quality is a kind of typical knowledge for supporting design decisions. In order to clearly identify and understand design decisions and their knowledge needs on manufacturing quality, an ontology of design decisions and manufacturing quality knowledge is developed. The methodology and tool used for the development of the proposed ontology is firstly introduced. The design decisions are organized along with five main design phases ranging from planning and task clarification, conceptual design, embodiment design to detail design. The knowledge needs of different design decisions, especially on the manufacturing quality knowledge, are analyzed through competition questions. Then, the ontology is built in the form of a hierarchical structure through the proposed methodology and ontology editor. Based on the developed ontology, further instances of the classes in the ontology can be filled as detailed knowledge, and can be accumulated for further construction of knowledge base.

Engineering design is knowledge intensive process in which large quantities of decisions are involved. Designers request large amounts of knowledge when making decisions. Manufacturing knowledge on product quality is a kind of typical knowledge for supporting design decisions, however, which is not considered and used effective and efficiently through formal feedback from manufacturing to design. In order to support design decisions, the first problem to be solved is to identify design decisions and their needs on manufacturing quality knowledge. One ontological approach is proposed in this work to solve this problem. An ontology is a formal, explicit specification of a shared conceptualization [G1]. "Conceptualization" refers to an abstract model of phenomena in the world by having identified the relevant concepts of those phenomena. "Explicit" means that the type of concepts used, and the constraints on their use are explicitly defined. "Formal" refers to the fact that the ontology should be machine readable. "Shared" reflects that ontology should capture consensual knowledge accepted by the communities" [G1]. Engineering design researchers are increasingly interested in the development of an ontology for engineering design [START_REF] Ahmed | Engineering design ontologiescontrasting an empirical and a theoretical approach[END_REF]. Engineering design ontology is a hierarchically structured set of terms for describing engineering design domain that can be used as a skeletal foundation for a knowledge base. One particular motivation for developing engineering design ontology is to provide a structured basis for navigating, browsing and searching information through the hierarchical descriptions of the ontology. It can help the collaborative design team by providing accurate design information and guidelines. This is especially useful when designers are not aware of the information available or have difficulty in forming suitable queries. However, most constructed ontologies focus only on the design activities and design process, and few works consider the manufacturing issues when constructing the design ontology. In this work, an ontology named "Design Decisions and Manufacturing Quality Knowledge (DD-MQK)" is developed for identifying the design decisions and their MQK needs. The paper is organized as follows: the methodology and editor for the development of the proposed ontology are illustrated in section 2. Then the ontology is developed along with seven major steps in section 3. Section 4 concludes with discussion and further works. When this is done knowledge about the real world can be captured. It is by repeating this process that a knowledge base can be developed, since a knowledge base is a collection of instances of classes of interest for a given task. The Noy and McGuinness methodology is thought to be the most appropriate one for developing the "DD-MQK" ontology because it has clear logic steps and is very suitable for developing frame-based ontology. Thus, the Noy and McGuinness methodology will be chosen for building of the frame-based ontology "DD-MQK".

2-Methodology and tool for building ontology

-Methodology for building "DD-MQK" ontology

-Ontology editor-Protégé

The Protégé developed by Knowledge Systems Laboratory (KSL) is the most widely used ontology editor tool. Protégé is a free, open-source platform that provides a growing user community with a suite of tools to construct domain models and knowledge-based applications with ontologies. At its core, Protégé implements a rich set of knowledge-modeling structures and actions that support the creation, visualization, and manipulation of ontologies in various representation formats. Protégé can be customized to provide domain-friendly support for creating knowledge models and entering data. Further, Protégé can be extended by way of a plug-in architecture and a Java-based Application Programming Interface (API) for building knowledge-based tools and applications. The Protégé platform supports two main ways of modeling ontologies: The Protégé-Frames editor and The Protégé-OWL editor. The Protégé-Frames editor enables users to build and populate ontologies that are frame-based. In this model, an ontology consists of a set of classes organized in a subsumption hierarchy to represent a domain's salient concepts, a set of slots associated to classes to describe their properties and relationships, and a set of instances of those classes -individual exemplars of the concepts that hold specific values for their properties. In this work, the Protégé-Frames editor is chosen as the tool for building DD-MQK ontology. For more information about Protégé, please visit the website of Protégé [P1].

3-Building of "DD-MQK" ontology

Before the investigation and organization of the subject content of engineering design decisions' MQK needs, a conceptual framework of related topics is formulated. The top level of the structure is shown in Figure 1. Three major topics are formulated including decision-maker, design decision, and MQK. Their elaboration and detailed hierarchy will be discussed in following subsections. According to the methodology, this section illustrated the detailed development of the ontology. For clarity, it should be noted that only part of DD-MQK ontology is used to illustrate the development methodology.

-Determining the domain and scope of the ontology

One of the ways to determine the scope of the ontology is to sketch a list of questions that a knowledge base should be able to answer based on the ontology. If we can answer these questions correctly, the ontologies will be developed easily. These questions are referred to as competency questions [START_REF] Gruninger | Methodology for the design and evaluation of ontologies[END_REF]. These questions will serve as the litmus test later: Does the ontology contain enough information to answer these types of questions? Do the answers require a particular level of detail or representation of a particular area? These competency questions are just a sketch and do not need to be exhaustive.

According to the works of Darlington and Culley's work [START_REF] Darlington | Investigating ontology development for engineering design support[END_REF], crucial to the success of the ontology development is determining the domain and the scope of the ontology. Establishing this can be assisted by answering the following three questions:  What domain of interest will the ontology cover?

In this case the domain is that of product design decisions and their MQK needs, the content of which relates to such things as product design decision makers, product design decisions, product manufacturing, and product quality inspection, and the materials of which they consist or upon which they are placed.

 For what will the ontology be used?

The purpose of the DD-MQK ontology is to provide a knowledge context, which can assist the designers in raising and answering all the questions appropriate to completing the design decisions relating to the quality of a designed product.

In general, "knowledge context" might be defined as the prevailing conditions, environment or knowledge state by which an interpretation is made of the information.

 For what types of question will the information in the ontology provide answers? The competency questions are considered to be of immense importance in focusing on what the ontology is to be used for, and providing guidance as to the structure and content of the ontology. The use to which the ontology is to be put is critically important in deciding the level of description for the entities in the conceptual space (that this is the case can be seen from the examples given in Step 4). Competency questions assist in clarifying what the entities are, their natures, and at what level they might best be described. In addition, the competency questions provide a means by which the ontology, and its implementation in some problem-solving method, can be validated, since they can be used to query an application's performance. In the DD-MQK Ontology, some competency questions can be listed as follows: About the actors (including designers, manufacturing engineers, managers, etc.):  To what decisions does the actor (Manufacturing engineers/quality engineers, etc) contribute MQK?  For what decisions is the actor declared an expert or knowledge base?  What decisions and sub-decisions does the actor own?  What is the geographical location of the actor and the knowledge base? About the design decisions:  What MQK knowledge is required to make the decisions?  What information is generated by this decision?  Who are the decision makers (or stakeholders)? About the knowledge. Instances of the "knowledge item" class are chunks of knowledge, which may include a technical report, guidelines for using a software tool or advice from an expert on an issue associated with the task.  What tasks in manufacturing generate this knowledge item?  For what decisions does this MQK item provide knowledge?  Where is the knowledge item located?  What types of the format does the knowledge item exist as?  In what languages is the knowledge available? The competency questions need not be exhaustive, merely indicative of the sorts of questions that could require answering by a knowledge base founded on the ontology. However, in order to formulate the questions it is necessary that predictions be made about the use to which the ontology is to be put; it is difficult to see how the competency questions could be derived without having some sort of use in mind [START_REF] Darlington | Investigating ontology development for engineering design support[END_REF].

-Considering reuse of existing ontologies

There are a growing number of ontology libraries from which can be imported existing ontological structures, for example, the Ontolingua ontology library or the DAML ontology library. There are also a number of publicly available commercial ontologies (e.g., UNSPSC (www.unspsc.org), RosettaNet (www.rosettanet.org), DMOZ (www.dmoz.org). However, no source ontologies were judged to be directly useful in contributing to the ontology developed in this study, and this work will assume that no relevant ontologies already exist. So the ontology "DD-MQK" will be constructed from scratch.

-Enumerating important terms

Having established the scope of an ontology this step constitutes the starting-point for building a new ontology, and consists of the two tasks of (a) identification of the key concepts and relationships in the domain of interest and (b) production of unambiguous text definitions for such concepts and relationships. It is useful to write down a list of all terms this work would like either to make statements about or to explain to a user. What are the terms this work would like to talk about? What properties do those terms have? What would this work like to say about those terms? Initially, it is important to get a comprehensive list of terms without worrying about overlap between concepts they represent, relations among the terms, or any properties that the concepts may have, or whether the concepts are classes or slots. For this step, this work will take all the terms in the engineering design domain, especially from Pahl and Beitz's classic works [START_REF] Pahl | Engineering Design: A Systematic Approach (3rd Edition)[END_REF]. Some important terms have been emerged naturally through Step 2 in section 3.2. More terms will emerge in following steps.

-Defining the classes and the class hierarchy

The next two steps-developing the class hierarchy and defining properties of concepts (slots)-are closely intertwined. It is hard to do one of them first and then do the other. Typically, a few definitions of the concepts are created in the hierarchy and then the properties of these concepts are continuous described, and so on. These two steps are also the most important steps in the ontology-design process. This step consists of placing the selected concepts into some sort of hierarchical organization. Uschold and Gruninger identified three approaches to the development of the class hierarchy: top-down, middle-out, and bottom-up [START_REF] Uschold | Ontologies: principles, methods and applications[END_REF]. Although no approach is inherently better, the middle-out approach where the ontology is developed from basic categories has been found to be of benefit, not least because it is at this level that the most descriptive concepts in the domain tend to be clustered. Due to space limit, only the top levels of the classes and the class hierarchy of "DD-MQK" is presented, as shown in figure 2. Concerning the construction of class and their hierarchy in Protégé, here only some concepts in the conceptual design phase are illustrated for the analysis of the design decisions and their manufacturing quality knowledge needs, and for the construction of the part of the ontology. Conceptual design initiated from the requirement list (or design specification). This phase includes four major working steps in which there include different tasks and decisions. The major steps are:  Abstracting to Identify the Essential Problems, which includes broadening the problem formulation and identifying the essential problems from the Requirements List.  Establishing Function Structures, which includes identifying overall function, breaking a function down into subfunctions.  Developing Working Structures, which includes searching for working principles, combining working principles, and selecting working structures.  Developing Concepts, which includes firming up into principle solution variants, evaluating principle solution variants, and determine principle solution. Thus, the design decisions classes and class hierarchy are formulated (Figure 3). Along with the different working steps and the detailed working tasks for implementing working steps, this work can analyze their different manufacturing knowledge needs. As we know, there are many kinds of manufacturing knowledge for support product design decisions. With reference to the analysis of different quality problems in quality management domain, the problems can be analyzed from four viewpoints such as man, machine, material, method, and environment, often being called as 4M1E. Here this work focus the manufacturing knowledge on the 3M such as material, machine, and methods (in this work we call it manufacturing process). The detailed manufacturing knowledge class and the class hierarchies are shown in Figure 4.

-Defining the properties of classes-slots

Classes or objects on their own provide only a limited amount of information about a domain, and it is usually insufficient to ensure that the competency questions can be answered. The addition of properties allows the internal structure of the domain to be added to the externalclassificationstructure. In a hierarchy, the property should be attached to the most general example in a class structure, subordinate classes acquiring the property by inheritance.

There are a number of types of property that can in general be assigned to objects or classes.  Intrinsic properties, including such things as mass, hardness and melting point.  Extrinsic properties, including such things as the name of materials or the price.  Parts, where an object has a decomposable structure. The 'parts' can be physical (e.g. in decomposing an assembly into components) or abstract (e.g. the stages of a process).  Relational properties. These are relationships between individual members of a class and other objects. Some of the slots of the classes are shown in figure 5. The class "Identifying Evaluation Criteria" has some slots such as "Name", "Need", and "Derived from", etc. After defining the slots of the properties of the classes such as design decision and manufacturing knowledge, this step will fill all the corresponding values of the different properties. As we know, in Protégé 3.3.1 we call values of properties/slots as facets. Due to space limit, here only the definition of one slot "Need" is illustrated. As shown in figure 6, for the slot "Need" of the classes such as different kinds of design decisions, the value type of slot is instances, the allowed class is "Product Support Knowledge" which is the super class of manufacturing knowledge in our project.

-Creating class instances

The last step is creating individual instances of classes in the hierarchy. Defining an individual instance of a class requires (1) choosing a class, (2) creating an individual instance of that class, and (3) filling in the slot values. Creating an individual instance of a class consists of specifying the actual value of each of the properties of a specific instance of the class. When this is done knowledge about the real world can be captured. It is by repeating this process that a knowledge base can be developed, since a knowledge base is a collection of instances of classes of interest for a given task.

4-Conclusions and Future Works

For the purpose of identifying and organizing the manufacturing quality knowledge needs of different product design decisions, this paper build a preliminary ontology which can help us understand specific kinds of manufacturing knowledge that different design decisions need. The commonused methodology is adopted for ontology development. All the design decisions and related manufacturing quality knowledge are identified along with the engineering design process which is adapted from Pahl & Beitz's works. The DD-MQK ontology is constructed by using the ontology editor named Protégé. Based on the DD-MQK ontology, more and more detailed knowledge, for example the knowledge extracted from domain expert or from manufacturing data, can be filled as instances of the classes in the ontology. With long term accumulation, the knowledge in the ontology can be exported and used for further construction of manufacturing quality knowledge base for supporting design decisions, which is the most important part in future works.

Figure 1 :

 1 Figure 1: Conceptual framework of DD-MQK ontology.

Figure 2 :

 2 Figure 2: Top levels of DD-MQK class hierarchy.

Figure 3 :

 3 Figure 3: Class and class hierarchy of design decisions in conceptual design.

3. 6 -

 6 Defining the facets of the propertiesProperties in the real world are described by value type, allowed values or perhaps ranges of values, the number of values (the cardinality) and other features that the property has. These are sometimes (as is the case in Protégé 3.3.1 terminology) known as facets.

Figure 4 :

 4 Figure 4: Part of class hierarchy of MQK.

Figure 5 :

 5 Figure 5: Slots of the class "Identifying Evaluation Criteria".

Figure 6 :

 6 Figure 6: Facets of the slot "Need".

  In recent years, there are two most widely known methodologies for ontology development, which are presented by Uschold & Gruninger [UG1] and Noy & McGuinness [NM1] respectively. The approach taken by Noy and McGuinness overlaps with and is influenced by Uschold and Gruninger's work. It provides guideline for the development of a declarative frame-based ontology. The key elements of the methodology are illustrated as follows:  Step 1: determining the domain and scope of the ontology:Establishing the domain and the scope of the ontology can be assisted by answering the following three competency questions[START_REF] Gruninger | Methodology for the design and evaluation of ontologies[END_REF]: What domain of interest will the ontology cover? For what will the ontology be used?

	For what types of question will the information in the ontology provide answers?  Step 2: considering reuse of existing ontologies: There are a growing number of ontology libraries from which can be imported existing ontological structures.  Step 3: enumerating important terms: This step consists of the two tasks of (a) identification of the key concepts and relationships in the domain of interest and (b) production of unambiguous text definitions for such concepts and relationships.  Step 4: defining the classes and the class hierarchy: This means placing the selected concepts into some sort of hierarchical organization. Uschold and Gruninger identified three approaches to the development of the class hierarchy: top-down, middle-out, and bottom-up [UG1].  Step 5: defining the properties of classes-slots: Classes or objects on their own provide only a limited amount of information about a domain, and it is usually insufficient to ensure that the competency questions can be answered.  Step 6: defining the values (facets) of the properties (slots): Properties in the real world are described by value type, allowed values or perhaps ranges of values, the number of values (the cardinality) and other features that the property has. These are sometimes known as facets.  Step 7: creating class instances: Creating an individual instance of a class consists of specifying the actual value of each of the properties of a specific instance of the class.

5-Acknowledgments

This work was funded by National Natural Science Foundation of China (No: 70472066, 70771091), the project of Bureau of Science, Technology and Industry for National Defence, China (No. Z142008A001), the NPU Foundation for Humanities, Social Science, and Management Science Development (No. RW200817), which are gratefully acknowledged.


Julien Gardan
email: julien.gardan@arduinnova.com

Lionel Roucoules
email: lionel.roucoules@ensam.eu

Wood has several advantages that are transferable to various derivates allowing the introduction of a sustainable material into the product lifecycle. Our study is to apply a DFM approach based on wood flour rapid prototyping, while associating the requirements of the "mass market product" in the implementation of a customized product. New communication tools allow consumers to be involved in the design process. Prototyping processes allow direct manufacturing of products.

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The market for "mass market product" has evolved in recent years towards customizable products. This market change has created new offerings not based on existing markets as in the past, but generating a new application. This new behaviour has somewhat changed the decision to make process related to product design. Make a good product is necessary to be competitive, but unfortunately not enough; one should also make so the right product, that means the product that fits to the users real needs and expectations [SG1]. Many domains (automotive domain) use methods focused on the user. It is shown that the involvement of users and their perceptions is critical to the design [P1, M1 and R1]. As the manufacturability of the product is also crucial, several intrinsic parameters, related to the manufacturing process, are added to the design process. The notion of "sustainable" products is an important concept. It leads to the use of materials and manufacturing processes compatible with respect of the environment throughout the lifetime of the product. The environment of a product has an impact on its life cycle. By specifying environmental compared audits, also called life cycle analysis (LCA), we show that the wood has obvious advantages and appears as an "environmentally responsible" solution [TT1].

The business purpose of the company Arduinnova, is to provide customized on demand product for the "general public" with a production of unit objects. As the reproducibility of products needs specific tools, Arduinnova has chosen the prototyping process.

This article discusses the integration of natural materials in our experimentation on beech wood pulp through two processes of prototyping for manufacturing reconstituted wood products: 3D printing and Solid Freeform Fabrication (SFF).

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Wood is a biodegradable organic material which is more or less long term reinstated in the natural carbon cycle. The cycle analysis (LCA : Life Cycle Analysis or Assessment) reveals the global strengths of the material. LCA takes into account the environmental impact of the subsequent stages of the life of the wood preparation and extraction, processing, transportation, installation, performance usage and recycling. Information on the life cycle of wood are still new and dispersed [TT1], but we can mention a few main areas:

-Operation is less polluting than the extraction of other materials.

-The transport does not involve any risk and its supply is closer.

-It requires less energy and less water than other materials.

-The exploitation of under-products of wood is in development, and wood energy is neutral in CO2 production.

Wood takes part in the reduction of carbon dioxide emissions as an alternative to non-renewable materials, the latter leading to energy costs and negative impacts that are hard to be sustained by our ecosystem. The life cycle of wood includes certain compounds that involve all materials using wood material processed as main base, such as plywood, particle board, fiber, etc. The interest of these products is For example, potato starch is used in industry to manufacture glue wallpaper, biodegradable by etherification (described in Table 2). The introduction of new hydroxylated functions provides a moisture level equivalent or superior to that of native starch. The chemicals are not longer present in the final modified product, it is completely biodegradable. However, it should be noted that the character of the starch as a natural substance decreases with increasing etherification.

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Name Chemistry Food manufacture Ether starch

Hydroxypropyl starch E 1440

Table 2: Modified starch.

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We realized the Life Cycle Analysis. It shows this process don't consumes resources but this is not the aim of the paper.

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We had access to a 3D printer, the ZCorp 510, which by default uses a powder made from gypsum and a binder distributed by ZCorporation. Details of the compounds used are usually secret which will not facilitate the interpretation.

That technique is a mixture of projection of binder and sintering. A print head including several nozzles, to enable colour printing, throws droplets of binder over a tray of powdered material. Binder penetrates the agglomerates and the powder becomes rigid. A post-processing based glue is necessary to obtain sufficient mechanical strength.

Our choice is based on its handling, which allows us easy access to trays containing gunpowder and printing system consisting in containers, canals and printheads standard type Hewlett Packard. The entirety seemed workable for us to integrate our natural products.

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Solid freeform fabrication (SFF) has the potential to revolutionize manufacturing, even to allow individuals to invent, customize, and manufacture profitable goods in their own homes. The open-source Fab@Home project has been created to promote SFF technology by placing it in the hands of hobbyists, inventors, and artists in a form which is simple, cheap, and without restrictions on experimentation [ML1].

The method is based on the extrusion of material in the form of paste (silicone, chocolate, pastry dough ...). One or more needles, guided by three digital axis, lay down a dough thread. The filament does not solidify immediately. The strata of the object are constructed by stacking a specific track connected with a free open-source (we can find the same type of software on the RepRap [B2]). The syringe connected to a plunger deposits its thread in a horizontal plane, then the platform is lowered to start make room for the

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This approach could allow us to make a wood pulp to form some objects.

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Main objective of shaping is to get aesthetical parts and to obtain mechanical properties corresponding to the constraints of use. This implies mechanical performances through tests, and good shape thanks to behaviour of the pulp (keeps its structure from the beginning to the end).

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On the use of ZCorp 510, we could easily incorporate the flour Beech HB 120 in the printer and do initial testing with the binding machine ZB58 transparent. The binding machine is suitable for a hydraulic material; we could assume the hypothesis that the binding machine is not as effective on wood flour. We ended up with very friable pieces in printer output.

As the available sensors were not precise enough, we performed tests of toughness by penetration thanks to a low mass ball to characterize this fragility described in Table 3.

Diameter footprint Weight ball

Yield strength Re 4,5 mm 20 g 1,23 MPa Table 3: Toughness penetration.

This result is achieved through the average of the measures of several prints on a specimen (Figure 1) placed horizontally on an undeformable support (marble of a coordinate measuring machine). The structure and brittleness give varying impressions, which bring into question the reliability of the results but allows us to devalue the fragility of the object in printer output. Our results are too low; we focused on the adaptation of a natural binder to project through the print heads. We encountered a lock technology, the size of the projection (in pico-liter) induced a fluid binder and a viscosity adapted to the use of print heads micro-nozzles. As our specialty is not the chemical composition of the binders, we seek suitable solutions.

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Because we don't have the fab @ home system, we decided to kit the manufacturing process. We are therefore using open-source software for the RepRap (RepRap for "replication rapid ") generated from a plot of the STL deposit thread paste. Then we translated specific code in gcode applicable to a CNC machine. By adapting a syringe instead of the machining system (the milling), we could confirm our application but manually making the filing of the wire, that is to say by applying manual pressure on the syringe to lodge a "wood pulp" test initially.

This first test confirm our guidance taking into account the automation of the wire deposit to be applied on the syringe, a step that does not seem to be a lock technique because we can integrate a jack or an endless screw coupling system of feeding the milling machine. The adjustment of extrusion parameters generated by the RepRap software and machining parameters to predict a step necessary for the extrusion of our pulp is workable.

We can use this manufacturing method to try to realise our wood products. The first problematic relies upon the dough consistency and notably its rheological characteristics to obtain a thread that will not collapse during the lay down.

The second problematic is to respond to geometric and use constraints of the product after dough drying.

We propose to implement a design of experiments (DOE) focused on holding the wire to get the best possible deposit in the manufacture and on its geometrical and mechanical characteristics after drying.

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The method of DOE can both reduce the number of tests, and study a large number of factors, but also to detect possible interactions between factors. The study of the influence of one factor at a given level is done by comparing the average responses obtained at this level to the overall average [AA1 and P3]. According to the definition of full factorial, one has an answer for each combination.

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We choose to apply this method in order to discover the effects of the process and of the chosen material (thanks to the first experiences plan) on various predefined geometrical shapes without increasing tests.

Our literature search has identified influential factors such as high sensitivity of the materials to moisture (wood and starch).

Objective: To assess the various factors that makes up pulp from its mechanical behaviour and rheological criteria.

Consequently, the studies on the relative influence of parameters are the parameters that influence a priori significant, namely:

-The grain sizes of beech flour: 40 µm and 120 µm -The mass of beech flour: 20 g and 40 g -The mass of ether starch: 10 g and 40 g -The volume of demineralised water: 200 ml and 300 ml " )

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Test pieces are samples with non-constant geometry (Figure 2). The geometry of this is presented in picture 3 (Depending on the composition of the pulp, pieces do not look the same). The structure can vary from one specimen to another. We realize 3 samples per dough type and we will average the set of results (to avoid the spread). We produced the test manually without CNC. Technically the filing of the wire is feasible, but our resources do not permit us to automate the descent of the plunger. Manufacturing parameters of specimens:

-Wire diameter: 2 mm -Temperature: 20 ° C -Humidity: 55% RH -Material: Beech flour 20 µm and 120 µm (deciduous)

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The measurement of mechanical strain is performed on a machine for strain-compression with a sensor 100 daN. The deformation is measured on the initial length (L0%); the measure of stress is MPa. The tests are conducted in an environment at a temperature and humidity of 42% RH.

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We have no tools at our disposal to directly measure the rheology of the pulp. We applied the criteria of observations to assess the wire held: Good behaviour: criterion n° 1; Medium behaviour: criterion n° 2; Worse behaviour: criterion n° 3.

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The DOE is performed on a tension and compression machine using the conditions mentioned in the previous paragraph. We have a two-level plan, with the study of all the possible bilateral interactions per sample type, which corresponds to an L 16 table. The levels chosen are shown in table 5. The conditions were chosen on both sides of the test conditions of reference presented in the preceding paragraph. The relative importance of a parameter is estimated using graphs like those in Figure 2. The importance of the slope on each parameter gives information on the importance of the influence of this parameter. The more the factor's effect is important, the stronger the segment's slope is. It was therefore a means of quick visual assessment on the same graph of the relative influence of representative factors detailed in Figure 3. An interaction between factors occurs when the modification of the response obtained on minimum level or on maximum level of a factor differs from the modification of the response on two identical levels of a second factor. In other words, the effect of a factor depends on another factor. You can use interaction diagrams to compare the relative strength of the effects of different factors.

Factors

We want to avoid the wire held during manufacture to meet the maximum geometric dimension of our shapes. We can study the factors affecting this behaviour.

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The responses optimization function searches a combination of input variables that jointly optimizes a set of answers while satisfying the required conditions for each response of the set. To optimize the manufacturing conditions of our forms, we must define an individual desirability for each response. We must therefore increase our desire to obtain the best possible wire place during manufacture while maintaining a tensile high stress. We keep the goals while maximizing the responses.

The optimization diagram illustrates the effect of each factor on the responses or composite desirability. For the individual desirability we select a weight (between 0.1 and 10) to define the importance of the reaching of the target value. In our study, the composite desirability (0.86) is fairly close to 1, indicating that the settings seem to achieve favourable results for good performances of the thread during the manufacturing and it responds to using features.

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Modified starch used is the most important factor affecting the tensile strength of the material. The flour beech fiber size may affect the resistance in our setup, contrary to what we thought. The starch needs enough water and does not need a high load of flour to achieve its characteristics.

For holding the wire on filing, it is more stable when the pulp is made up of less water and more flour. Starch is undeniably the invariant factor in our composition. The study shows that interactions of beech flour and starch have a strong responsibility to hold the wire in the presence of demineralised water. With the aim to improve our wood pulp, we headed towards the responses optimization to be closer to the best of our terms of use and manufacture.

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In order to adapt the consumers' products design to the manufacturing process and to the material used, we want to integrate knowledge to link functional specifications to the product before its manufacturing. Manufacturability's analysis and application of guidelines to improve design

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-6-solution are strongly related to a know-how linked to manufacturing problems. However, they do offer no real model of formal integration. This is done "mentally" on the originally defined product data (often geometric data) [S1 and SR1].

Data models have been proposed by several authors, which allow to model the design activity and to conserve a cooperative aspect between different actors that may intervene in the product's design. These models are related to design methods which, while remaining within the philosophy of concurrent engineering, have their own particularity [SR1].

.

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According to the approach we must develop proposals that are adapted to each area depending on the product. For example, for manufacturing area, we can now specify that our product has a better geometrical stability (minimized collapse when the laying on the thread) using a paste according to the composition described in Table 7. It is a truth demonstrated by experiment, directly affecting the manufacturing features.

We know the sensitivity of our materials to moisture; we can define in the product's using space that objects will not be adapted to high humidity conditions. (below 70% RH depending on the characteristics of starch. For example, not in the external environment or in a bathroom), but our hygroscopic material remains mechanically and geometrically variable throughout its life, depending on temperature and humidity variations of its environment. We must add these parameters to the dimensional changes of our material after curing.

The relationship between feature and form is achieved through a grammatical approach generally to define a representation of a function by a noun-verb pair [WM1]. This representation should permit linking feature to form. This approach allows the definition of axioms and rules together with a specific vocabulary. All rules are still to be defined before they can be associated with the setting of a CAD model.

All these definitions will allow us to link design parameters to our product, or more precisely, to functions of manufacturing, use, or even recycling in end of life.

% 3

We have to realize a study case using our design and manufacture method. It concerns a scotch-tape winder, which perfectly matches the consumers' products family. The importance of measuring the roughness of our material to foresee the friction of the rolling is all the greater that it will apply to our study case. One of our goals is to automate the manufacturing process.

-

[AA1] Alexis j and Alexis P. AFNOR Pratique industrielle des plans d'expérience, ISBN 2-12-465038-6, 1999 9,2,1994

Figure 1 :

 1 Figure 1: Several prints test.A post-treatment was considered by dipping a form in vegetable wax to increase our required forms. Tensile tests were performed on a tensile testing machine from a family of three specimens. The results of standard test-tube tension were unsatisfactory (Table4).

Figure

  Figure 2: samples geometry

Figure

  Figure 3: Graph of main effects

Table 1 : Beech flours.

 1 based on their economic, technical and commercial assets. The structural differences that can be found in one essence, lead to a certain amount of qualities and criteria for variable use. Any material that has little value which can be recycled is collected, crushed, shredded, fiberised, and may result in reconditioned wood material like the wood flour, with or without the addition of binder to give advantageously paper, cardboard, fiberboard or particles [P2]. The timber has a very competitive sale price compared to solid wood although the mechanical performances are lower. Their techno-economic value offers significant opportunities for industry sectors of construction, layout, and furniture incorporating recognized decorative techniques. The appearance and aesthetics of wood is undoubtedly an advantage for this material. But its use in wood derivatives shows that other applications are possible without translating the aesthetic and structural advantages of wood.

	With the integration of flour as main element in a process such
	as prototyping, it would be possible to obtain a homogeneous
	and isotropic material, unlike solid wood. Its high sensitivity to
	humidity forced to limit the use of such material. In our
	experiments, we use beech flour with two different grain sizes
	detailed in Table 1: LIGNOCEL HB 120 and ARBOCEL HW
	630.
	Name	Structure	Grain size	Density
	HB 120	Fibrous	40 -120 m	140-200 g/L
	HW 630	Fibrous	20 -40 m	200-300 g/L
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	Processes operate at a temperature below 40°C for the 3D
	printer, and at room temperature for the deposition modelling
	process. We focused on native starches and modified starches
	to study their behaviour through research in the scientific
	community. Starch is the main carbohydrate reserve substance
	of higher plants. It represents a significant mass fraction in a
	large number of agricultural commodities such as cereals (30%
	to 70%), tubers (60% to 90%) and vegetables (25% to 50%).
	The native starches, as maize or wheat starch, and potato starch
	form a presence of water in the vicinity of 50 to 70 ° C
	depending on the selected starch, with a rapid recrystallization
	of polymers (amylose and amylopectin) to cooling, called
	starch retrogradation [B1]. There are various modified starches
	that improve their behaviour. The chemically modified
	starches develop their viscosity and their binding property at
	low temperature or at normal cooking temperatures in
	environments where water availability is limited. This category
	gathers those modified starches obtained by reaction of
	hydroxyl groups of starch with monofunctional agents to
	introduce substitution groups. The purpose of this type of
	treatment is to stabilize the amylose against the retrogradation
	and prevent intermolecular association of amylopectin
	fractions. The introduction of ester or ether groups in the starch
	molecule can stabilize the viscosity, especially at low
	temperatures [CJ1]. The surplus products of the reaction must
	then be removed by washing to obtain a completely
	biodegradable starch. Note that starch is sensitive to humidity
	and its mechanical properties decrease with increasing
	moisture.

Table 4 : Tensile test on a specimen soaked in a vegetable wax.

 4

Table 5 : Levels table We

 5

					Level 1	Level 2
		Ether starch		10 g	40 g
		Beech flour		20 g	40 g
		Grain size		40 µm	120 µm
		Demineralised water	200 ml	300 ml
	N° Ether	Beech	Water	Grain	A	B	C
		starch	flour	(ml)	size	(Mpa)	(Mpa)
		(g)	(g)		(µm)
	1	40	20	300	40	7,30	719,0	2
	2	40	40	200	40	2,69	289,0	3
	3	10	20	200	40	0,16	21,6	2
	4	40	40	300	40	1,01	113,3	3
	5	40	40	200	120	0,53	65,0	3
	6	10	40	200	120	0,31	45,6	3
	7	10	40	300	120	0,01	2,00	2
	8	10	20	300	40	0,29	39,33	1
	9	40	20	200	40	1,11	98,33	3
	10	10	40	300	40	0,01	2,00	2
	11	40	20	200	120	2,49	274,3	3
	12	10	40	200	40	0,41	64,3	3

find below the construction design of experiments in table

6

. The specified outcomes are the averages of measurements performed in tension on a family of three identical specimens. To summarize, we have three answers: the maximum strain in MPa named A, the modulus of elasticity in MPa, named B and rheological criteria assessed during the extrusion performed with a syringe, named C.

Table 7 : Optimization responses

 7 The composite desirability is the weighted geometric mean of individual desirability of different answers. The table summarizes the results and "best" configuration to simultaneously maximize our responses.

	Composite Desir	Maximum strain	Wire held criteria
	0,86		3,5 MPa		1,35
	Grain size	Ether starch	Beech flour	Water
	40 µm	40 g		24,64 g	246,46 ml

[ B1 ]

 B1 Boursier B. Amidons natifs et amidons modifies alimentaires. Techniques de l'ingénieur, 2005 [B2] Bowyer A. "RepRap", available at www.reprap.org, 2007 [CJ1] Chavanne M., Jullien A., Beaudoin G. J. and Flamand E. -Chimie organique expérimentale (2ed, 1991 -Modulo). Mantelet F. Prise en compte de la perception émotionnelle du consommateur dans le processus de conception de produits, Thèse LCPI, ENSAM, CER Paris, 2006 [ML1] Malone E. and Lipson H -Fab@Home: the personal desktop fabricator kit. Mechanical and aerospace Engineering, Cornell University, Rapid Prototyping Journal, Emerald Group Publishing, 2007 (available at: www.fabathome.org ) [P1] Poirson E. Prise en compte des perceptions de l'utilisateur en conception de produit. Application aux instruments de musique de type cuivre, Thèse IRCCyN, ECN, Université de Nantes, 2005 [P2] Plassat F. Mise en oeuvre du bois, Techniques de l'ingénieur-B 7 304, 1994 [P3] Pillet M. Introduction aux plans d'expériences par la méthode Taguchi. Les éditions d'organisation, 1992 [R1] Rouvray A. Intégration des préférences émotionnelles et sensorielles dans la conception de produits d'ameublement : proposition d'une méthodes d'ingénierie affective, Thèse LCPI, ENSAM, CER Paris, 2006 [S1] Swift K-G., Brown N-J. Implementation strategies for DFM, Journal of Engineering Manufacture, vol.217, P827-Winsor J., Maccallum K. A Review of Functionality Modelling in Design, The Knowledge Engineering Review,

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	design, International Journal of Design and Innovation
	Reasearch, Vol-1 n°2, nov 1998, P22-35, 1998
	[SR1] Skander A., Roucoules L., Klein Meyer JS, Design
	and manufacturing interface modelling for manufacturing
	processes selection and knowledge synthesis in design,
	International Journal of Advanced Manufacturing
	Technology, 2007
	[TT1] Trouy-Triboulot M.C., Triboulot P. Matériau bois -
	Structure et caractéristiques, Techniques de l'ingénieur-C
	925, 2001
	[WM1]