Ariane Bazan
email: ariane.bazan@rug.ac.be

Filip Geerardyn

Veroniek Knockaert

David Van Bunder

Gertrudis Van De Vijver

Anticipation as Exercising (Language) Motor Programs During Dreams. A Neuropsychoanalytical Hypothesis

Keywords: anticipation, dream, psychoanalysis, phoneme, lexicon

A neuropsychoanalytically framed hypothesis considering dreams as the 'motor exercising' of humans most typical behavior, namely language, is presented. In psychoanalysis dream bizarreness is often resolved by reading the dream content textually. It is defended that this literal interpretation comes down to analyzing language on its articulatory or phonemic structure. While in awake language, lexical (or ego) control is exercised in such a way that scansion of the phoneme structure is operated meaningfully in line with the context, this control is thought not to operate in dreams where it is the motor part (i.e. the articulation) which is thought to be important. The uncontrolled running of these articulatory programs could then result in phonemic ambiguities, thereby accounting for the bizarre elements of the dream.

Introduction

Clinical Fragments

The starting point of this paper is a clinical observation recurrent in dreams. This phenomenology is illustrated in three clinical fragments, gathered by analytical clinicians (personal communications, 1999-2001). Common to these dreams is the observation that an a priori not suspected and conceptually not related alternative interpretation of the dream is accessed upon a literal reading of the dream story as told by the dreamer himself. This is essentially similar to what Freud (1900[START_REF] Freud | The Interpretation of Dreams (J. Stratchey, translator)[END_REF] repeatedly demonstrated in his 'Interpretation of Dreams'.

• An English-speaking woman dreams that she and her therapist are sitting in front of each other. They are sitting in such a way that the soles of their feet are touching. The woman says: "We were sitting sole to sole.". Upon saying this aloud, she suddenly hears the similarity of this sentence with its phonological analogue: 'soul to soul' and thereby gets access to another interpretation of her dream.

• A French-speaking pregnant woman dreams she is driving a big Mercedes down a spiral garage driveway. While she is driving the car, the driveway gets narrower and at one point her Mercedes gets stuck. The therapist asks her attention for 'la Mercedes': "Why a Mercedes?". When the woman gains access to an alternative reading of this element, namely: 'la mère cède' or 'the mother fails/gives up', a new signification of her concerns becomes clear. The woman was at that moment preparing for the presentation of her PhD thesis and therefore experiencing some conflict between this time-and energy consuming achievement and her imminent motherhood. • A Dutch-speaking young man dreams he is flying with a rocket to the universe. The therapist avoids focussing primarily upon a possible 'phallic' interpretation and thereby avoids understanding the elements of this dream as symbols with a fixed meaning. Instead, she asks the man's attention for the Dutch word 'universum' ('universe'). The man indeed is himself somewhat astonished about his choice and mentions he normally would not use this word, but rather one of its more current Dutch synonyms (namely 'heelal' or 'ruimte'). He then freely associates upon this word 'universum' and immediately switches to the neighbouring word 'universiteit' ('university'). He thereby gets access to the frustration and shame he experiences not having finished his university studies.

Problem Statement

These three clinical fragments illustrate an underlying dream process suggesting dreams are driven by a literal language processing. The question therefore is: "What specific language dynamics are thought to be at the basis of these dream processes, how do they differ from awake conversational language and what sense does this make from a functional or evolutionary point of view?". Based upon both clinical and neurophysiological evidence, the idea of two different language dynamic systems is defended and, in conclusion, the idea that the literal structure of dream language reflects an evolutionary dream function, namely that of exercising and stabilising strategic motor patterns. By adopting the Saussurian term of 'signifier ' (1915/1967) for the phonological element of the language, [START_REF] Lacan | The agency of the letter in the unconscious or reason since Freud[END_REF]Lacan ( /1977) ) anchors his theory in the fundaments of structural linguistics. Essential there is the notion of 'phoneme'. [START_REF] Saussure | Cours de linguistique générale[END_REF]/1967) defines phonemes as 'speech sounds distinguishing meaning'. In this definition the crucial point is the distinction between 'phones' or continuously varying speech sounds and 'phonemes' or more or less arbitrarily but categorically contrasting classes of speech sounds. In English e.g. the phoneme /p/ distinguishes tap from tab, tag and tan, and distinguishes pin from bin, din and kin. But this phoneme nevertheless includes several neighbouring phones, e.g. the phoneme /p/ has slightly different phonetic characteristics in pot, spot or top. Nevertheless these different phones are all perceived as belonging to the same phoneme in English. This is somewhat arbitrary since in Korean e.g. a distinction between these phones would still be heard and they would accordingly be classified as belonging to different phonemes. It is clear that perceiving language elements as different is a necessary condition for the attribution of particular meanings to particular phoneme combinations. An Englishman would not attribute different meanings to pot if the starting phoneme /p/ would artificially be replaced by the phoneme /p/ from e.g. top; a Korean person, however, could perfectly do so, since he or she would be capable of clearly distinguishing these words.

A Neuropsychoanalytical Language Model

Phonemes are Perceptual and Motor Categories.

In different domains -psychoanalysis, psycholinguistics and neurolinguisticsthe idea is defended that phonemes should not solely be viewed as perceptual categories but also as motor categories, and even possibly as categories constrained by a certain level of resonance between simultaneous perceptual and motor determinants. In conceiving phonemes as motor categories, phonemes are not seen as classes of phones but as classes of articulatory movements or articulatory gestures. It is then the particular constellation of proprioceptive feedback information from articulatory muscles and joints when voicing out a phoneme that characterises that particular phoneme. Identification would be possible whenever enough proprioceptive information is accessed as to single out one phoneme.

A straightforward objection to this view is of course the observation that one effortlessly gets access to the phonemic structure of speech solely by listening and apparently without any motor contribution to this process. It is for the dismantling of this view that different arguments coming from several disciplines have been presented.

• In psycholinguistics, attempts to map the minimal spectrographic acoustic elements that would permit to classify phones unambiguously to particular classes of phonemes have been inconclusive (for review, see [START_REF] Cutler | Comprehending spoken language: a blueprint of the listener[END_REF]. Adults show an impressive capacity to correctly classify broadly varying or highly impoverished acoustic information (e.g. coming from very different voice pitches and intonations) to the correct phonemes. [START_REF] Liberman | Perception of the speech code[END_REF] and [START_REF] Liberman | The motor theory of speech perception revised[END_REF] have therefore proposed the 'Motor theory of speech perception', which supposes that it is not a minimum of information to recompose a complete acoustic record that is traced by the listener, but rather that amount of information that could permit the reconstruction of the articulatory motor intention of the speaker. • In neurolinguistics, it is known since Ojemann's electric stimulation experiments (e.g. 1979Ojemann's electric stimulation experiments (e.g. , 1983Ojemann's electric stimulation experiments (e.g. , 1991) ) that stimulation of both perceptual and motor language areas (at either side of the Sylvian fissure) disturb the process of phoneme identification. More recently [START_REF] Price | Hearing and saying. The functional neuro-anatomy of auditory word processing[END_REF] have shown the implication of a particular part of the Broca area (the so-called 'motor speech centre') in listening. Moreover, this specific area seems to be functionally and anatomically different from the parts of this area implicated in active speech or short-term memory processes.

• Freud (1891[START_REF] Freud | On Aphasia (E. Stengel, translator)[END_REF] himself had already defended the idea of an active motor participation in listening and understanding. Based on his study of the clinics of aphasia (and in particular of the phenomenon of 'echolalia'), Freud (1891Freud ( /1978, pp. 91-92) , pp. 91-92) defends the idea that "understanding of spoken words is probably not to be regarded as simple transmission from the acoustic elements to the object association; it rather seems that in listening to speech with understanding, the function of verbal association is stimulated from the acoustic elements at the same time, so that we more or less repeat to ourselves the word heard, thus supporting our understanding with the help op kinaesthetic impressions.". In an earlier passage of the same study (1891/1978, pp. 73-74) he had already proposed the hypothesis that "we learn to speak by association a 'word sound image' with an 'impression of word innervation' (...) " and "by endeavouring to equate the sound image produced by ourselves as much as possible to the one which had served as the stimulus for the act of innervation of our speech muscles". He in fact introduces an enigmatic new element in these views, namely that of 'the impression' or 'feeling' of 'the language innervation'. It is highly improbable that he uses this description to indicate the proprioceptive feedback information of the articulatory system, which he clearly refers to as the 'kinaesthetic word image' (p. 73). Alternatively, a sound interpretation for this description is that of the 'efferent copy' which feed backs to the neocortex whenever an efferent motor command is leaving the motor cortex. These efferent copies inform the neocortex that a motor command has effectively been sent out, while the proprioceptive feedback informs the neocortex that a motor command has effectively reached the target (and been carried out). According to Freud, phonemic access is therefore gained whenever this motor innervation impression reaches some level of identity with a perceptual acoustic image in line with what was laboriously learned through association during infancy. By implying the innervation impression or efferent copy as the relevant motor element in this identification process, Freud (1891[START_REF] Freud | On Aphasia (E. Stengel, translator)[END_REF]) offers a solution to the possible lack of real proprioceptive feedback whenever language is textually conceived without really having been spoken. Indeed, it is probably not necessary to suppose that an articulatory movement was effectively carried out for a pattern of efferent copies to be produced. Rather, a silent pattern of internal speech, possibly implying an impoverished or abstracted phonological level, might be sufficient for the generation of a motor image of efferent copy information.

Conclusion

In conclusion, the idea is proposed that the first event in gaining meaningful access to language is the active deduction of articulatory intentions from the gathered acoustic information. Both producing and active listening to language seem to imply the involvement of motor programs. We therefore at first experience language as ambiguous phonemes, not making any difference between e.g. 'sole' and 'soul', since both signifiers are determined by the same acoustic and articulatory feedback information. Disambiguation of this raw phonemic information necessarily involves further downstream processing.

The signifier as an Empty Position

Signifiers are Understood by Anticipation.

In introducing the 'signifier' as the basic linguistic element (in contrast to de Saussure's choice of the 'sign') [START_REF] Lacan | The agency of the letter in the unconscious or reason since Freud[END_REF]Lacan ( /1977, p. 153, p. 153) also implies another dimension of the concept of the signifier, namely the signifier as 'an empty position'. He illustrates his approach by several examples. In conversation e.g., sentences like "I shall never...", "All the same it is..." or "And yet there may be..." are often understood before the real informative part is spoken out: the listener automatically anticipates the meaning to come. Whenever entering a train station in a new town, we readily interpret whatever is written upon a typical station sign as the name of that town, even if this name is commonly known to us in a different sense (e.g. Main). Actually, these examples illustrate the way pragmatical information given by a symbolic context (a conversation, a station sign) anticipates upon the meaning of signifiers not yet identified.

Other levels of information add to this anticipatory effect. It is clear e.g. that the syntax also commands the meaning of the particular signifiers. [START_REF] Lacan | The agency of the letter in the unconscious or reason since Freud[END_REF]Lacan ( /1977) ) illustrates this point with a verse of Victor Hugo's poem Booz Endormi ('La légende des siècles ', 1859-1883) in which an object is used as a personification for the central character 'Booz'. [START_REF] Lacan | The agency of the letter in the unconscious or reason since Freud[END_REF]Lacan ( /1977) ) argues that it is the positional structure of the sentence, as prescribed by the knowledge of the syntax, which is crucial in understanding language. Indeed, this structure carries the information enabling a listener to understand that whatever word, appearing in the position of the subject of a particular action, should be interpreted as the actor of that action, even if the common meaning of that word would not suggest so. In the verse chosen by [START_REF] Lacan | The agency of the letter in the unconscious or reason since Freud[END_REF]Lacan ( /1977) ) a number of human properties are ascribed to a sheaf. By the position of the word 'sheaf' the listener knows that 'sheaf' is the subject of the sentence and therefore necessarily a person; the sheaf then is understood as a personification for Booz.

But the syntactical anticipation upon the meaning of a signifier is of course a far more general phenomenon. It is in the first place the syntactical position, and only in the second place the particular nature of a signifier, that produces the meaning of that signifier. In a sentence like e.g. "Are we going to...?", whatever word after 'to', will be understood as the name of a place, even if the signifier has another far more common meaning (e.g. 'Main'). This is what [START_REF] Lacan | The agency of the letter in the unconscious or reason since Freud[END_REF]Lacan ( /1977) ) indicates when referring to the signifier as an 'empty position'.

A Signifier Structured

Language is Auto-Constructive in both an Anticipatory and Retroactive Way.

Actually, Lacan considers the process of signification as both anticipatory and retroactive: "…the sentence completes its signification only with its last term, each term being anticipated in the construction of the others, and, inversely, sealing their meaning by its retroactive effect." [START_REF] Lacan | Subversion of the subject and dialectic of desire[END_REF](Lacan, /1977, p. 303), p. 303). Therefore, he suggests that both a progressive and a regressive dynamic are at work in human speech. As indicated, the progressive dynamic is thought to work by anticipating the meaning based upon the specific place the phonemes are allocated to in relation to each other. It thereby tentatively provides 'good guesses' for the scansion of the sentence and for the isolation of lexical units (words). At some point in this dynamic process there is also access to the meaning of these lexical propositions. Lacan's view can therefore be seen as the combined movement whereby the possible semantic alternatives provided enhance the information level of the system, thereby regressively reducing the degrees of freedom for the possible scansion propositions. These combined progressive and regressive movement then would come to stabilisation at the 'best guess', which phenomenologically corresponds with the meaningful understanding of the sentence given its context.

The definition of anticipation that is therefore dealt with in this paper is that of 'strong anticipation', which is not -unlike weak anticipation -predictable. It thereby differs from Rosen's definition: "An anticipatory system is a system containing a predictive model of itself and/or its environment, which allows it to change state at an instant in accord with the model's predictions pertaining to a later instant." but is best in line with the suggestions of Van de Vijver (1998), considering anticipation as 'a dynamic movement or behavior that takes place between systems and their environment and that opens the possibility for each of the participants to be changed by it'. The difference pertains to the externalist stance Rosen expresses: "Anticipatory systems are to him not instances of complex, self-organizational and autonomous systems that are auto-constructive while building models from the environment. System and environment are taken to be seperable here, and the problem of stabilization between these two separable poles is solved in quite classical Neo-Darwinian terms" (Van de Vijver, 1998). Language, in contrast, seems to contain an internal auto-organizational dynamic capacity that is able to organize itself at a different -higher -level of functioning by seeking for a stabilisation point at the meeting of two opposing movements, a progressive and a regressive one.

Lexical Labels

Next to the pragmatic and syntactic level, a third anticipatory information level for the meaning of signifiers to come is suggested, namely a 'lexical' level. Next to or apart from imagining some hard-wired syntactical and more or less abstract preconstruction in which received sentences are necessarily coded, conferring the status of 'subject' to one position and of 'verb' to another, it is suggested that constraining information of signifiers to come is coded at the level of preceding signifiers. The kind of information coded at this level could be typically syntactical, like 'this is a verb', or 'this verb is typically followed by an object (i.e. this is a transitive verb)' but it could also be far more specific for the particular signifier (e.g. this word -namely 'to pour'necessarily has a liquid object), and therefore the level is conceived generally as 'lexical'.

An important ethological experiment illustrates this point. In an attempt to teach chimpanzees a human-like language, Savage-Rumbaugh (1986) used so-called 'lexigrams'. These pictures have an arbitrary relationship to the object or action they refer to. The chimpanzees were successfully taught to use the combination of the lexigrams for either 'give' and 'banana' or 'pour' and 'juice' in order to receive a banana or juice respectively. They were then given the four pictures simultaneously to freely express their wishes. The chimps however could not make any sense of this vocabulary and randomly indicated the lexigrams (e.g. 'pour give banana pour') or persevered indicating only the most recent learned combination. It appeared that the trainers actively had to unlearn all impossible combinations (e.g. 'give give' or 'pour banana'). Only after this laborious unlearning period the chimps gained access to some simple rules, including the use of an object with a verb and including the fact that the verb 'to pour' necessarily implies the object to be liquid.

This experiment reveals a crucial characteristic of human language, animals -in contrast to children -do not have automatic access to. Deacon (1997, p. 85) formulates this as follows: "the relationship that a lexigram has to an object is a function of the relationship it has to other lexigrams, not just a function of the correlated appearance of both lexigram and object". In other words, lexigrams do not only bear information about the object they refer to, but also about the lexigrams to come and, inversely, the meaning of lexigrams is also conditioned by the preceding lexigrams. A lexigram here is to be viewed as a signifier since it incarnates the concrete form of the language. This view therefore implies that there is information, coded at the level of the signifier that commands the use or the comprehension of the signifiers to come. It is easy therefore to generalise all this information (syntactical, lexical) as 'lexical labels', thereby supposing that this information is directly connected or labelled to the lexical entity.

The Model of Damasio and Caramazza

This concept of a true lexical level, concerned with information that is specifically designed for the use of a (spoken, written) language system and therefore different from the primarily experiential encoding, has found important grounding in the neurolinguistic work of Damasio and co-workers [START_REF] Damasio | A neural basis for lexical retrieval[END_REF][START_REF] Tranel | A neural basis for the retrieval of conceptual knowledge[END_REF] and of Caramazza and coworkers [START_REF] Caramazza | Lexical organization of nouns and verbs in the brain[END_REF][START_REF] Hillis | Representation of grammatical categories of words in the brain[END_REF][START_REF] Miozzo | On knowing the auxiliary of a verb that cannot be named: Evidence for the independence of grammatical and phonological aspects of lexical knowledge[END_REF]. [START_REF] Damasio | A neural basis for lexical retrieval[END_REF] make an essential distinction between a semantic level and a lexical level. While the semantic level is concerned with all experiential characteristics of the object world, encoded on various occipito-temporoparietal areas of both hemispheres, there seems to be a clearly distinguished lexical level, concerned with naming and encoded exclusively on the left temporal lobe. The distinction becomes apparent in anomic aphasia, when the patient, while clearly indicating the characteristics and the use of a pictured object, is nevertheless incapable of naming it.

The one crucial observation in the work of [START_REF] Damasio | A neural basis for lexical retrieval[END_REF] is that this lexical level has its own organization: lexical entities seem to be grouped by object category. [START_REF] Damasio | A neural basis for lexical retrieval[END_REF] distinguish three classes: animals, tools and unique persons. The grouping of these lexical systems is confirmed by the observed correlation between the site of focal lesion in the aphasic patients and the site of PET-activation in healthy volunteers. Other authors found comparable grouping criteria like living things, plants and man-made artefacts (e.g. [START_REF] Gainotti | What the locus of brain lesion tells us about the nature of the cognitive defect underlying category-specific disorders: A review[END_REF].

In its introducing commentary upon Damasio et al.'s Nature-article (1996) [START_REF] Caramazza | The brain's dictionary[END_REF] proposes a revised linguistic model in which an organised lexical level mediates between a phonological system at the one hand and a semantic system at the other. Work by his group [START_REF] Caramazza | Lexical organization of nouns and verbs in the brain[END_REF][START_REF] Hillis | Representation of grammatical categories of words in the brain[END_REF][START_REF] Miozzo | On knowing the auxiliary of a verb that cannot be named: Evidence for the independence of grammatical and phonological aspects of lexical knowledge[END_REF] and by others (De Renzi & di Pelligrino, 1995) has reported a similar observation in agrammatical patients: focal lesions correlate with selective deficits for particular grammatical classes (e.g. verbs, nouns, function words). He therefore suggests that a similar organization exists at the lexical level for syntax information next to Damasio's reported organization for object category information. In line with the preceding suggestion, the model of [START_REF] Damasio | A neural basis for lexical retrieval[END_REF] and [START_REF] Caramazza | The brain's dictionary[END_REF] therefore seems to confirm an organization with lexical labels indicating the object category and the grammatical class respectively. 2.2.5 Conclusion: a Lacanian Signifier as a Lexical Entity.

Several lines of evidence, both from clinical and experimental research, suggest the autonomous existence of a lexical level with an organised topography. This topography displays a grouped pattern from which the grouping criteria are seen as lexical labels. It is suggested that a 'signifier', as introduced by [START_REF] Lacan | The agency of the letter in the unconscious or reason since Freud[END_REF]Lacan ( /1977)), can be seen in this model as essentially similar to a lexical entity. Such a lexical entity indeed is determined by its different lexical labels in much the same way a signifier is anticipated by diverse pragmatic, syntactic and lexical constraints from the symbolic context. Moreover, the lexical determinations of a lexical entity are to be seen apart from its semantic connections in much the same way the anticipation of the signification of a signifier functions with a not yet (phonologically) identified and therefore empty signifier.

The Signifier Between Phonology and Semantics

An Integrated Model

In the preceding paragraphs we have hitherto discussed two approaches to the Lacanian concept of the signifier: the signifier as articulated in phonemes and the signifier as a lexical entity anticipated by its lexical constraints. The questions now are: how do both approaches integrate and how does this model throw light on the introductory phenomenology?

In constructing a coherent linguistic model we bring together both preceding arguments 1 : 1. It is the signifier as phonemic structure that is connected with the widely distributed semantic domains but this phonology in itself cannot disambiguate between various possible but dramatically different semantic connective networks. With the exclusive information /s l tu: s l/ e.g. access is evenly gained to two different semantic networks.

1 This view is in line with the status of the signifier as an anticipatory structure incarnating the relation between universal and particular as conceived in Greek philosophy and in particular by the Stoicians and Epicurians (for discussion, see [START_REF] Van De Vijver | Anticipatory systems, a short philosophical note[END_REF]. Lexical labels indeed indicate word classes and therefore function as abstractions of the signifier to be identified. The universal can therefore be considered as the empty position with its lexical labels at the one hand and the particular as the phonemic structure of the identified signifier at the other.

2. The signifier as lexical entity gathers a bunch of categorical information permitting selection between competing alternatives as to its signification. This information, however, results from constraints given by the preceding signifiers. It is therefore anticipated and does not require the identity of the particular signifier to be known yet. In this view the lexical function of the signifier is not considered to be directly connected with semantic domains and is therefore said to be empty. When phonemic and lexical information work in resonance lexical constraints can disambiguate between the phonologically activated semantic networks and the signifier is understood in line with its relevant context.

Disconnecting Phonology and Lexicality

It is essentially the possibility of disconnecting both functions -phonological and lexical -that is the crucial point of this discussion. In this disconnection two different kinds of language functioning are distinguished: one in which there is an associative access to semantics that is not directed by contextual constraints and one in which these constraints are taken into consideration in order to access an interpretation that has verified its pertinence in function of the given context. Some clinical situations (dreams, free association) give us a cue as to the possibility of a relatively separate functioning of these different language dynamics. In dreams indeed bizarreness often results from the incongruity of the dreamed situation given the settled context (e.g. why would one sit sole to sole with his therapist?). In free association also one is not bound to congruity, logic, coherence, verification with reality etc. but is encouraged to let its thoughts wander freely. It is then observed that the internal logic of both clinical situations is built at least partially upon phonemic regularities, something that is of course not intentionally aimed at in awake conversation language. This is, we are not planning to sit with soles joined whenever we want to be emotionally close to someone, or we do not intentionally talk about rackets to the universe whenever we want to express feelings about the university. But, amazingly, we sometimes do seem to follow this kind of logic, as becomes clear from dream narratives or by free association.

The question at this point could be formulated as: what is at a neurolinguistic level the crucial difference between both ways of language functioning? One good proposition comes from [START_REF] Deacon | The symbolic species. The co-evolution of language and the human brain[END_REF], who in his book 'The symbolic species' builds his arguments upon a coherent overview of ethological, clinical, experimental, anatomical and neurophysiological results. The author defends the idea that it is essentially the prefrontal cortical functioning that enables humans to switch from an animal like indexical -exclusively associative -interpretation of tokens (words, signifiers) to a symbolic interpretation in which the understanding of a token is made a function of its relationship to the surrounding tokens. The prefrontal contribution is in this context an inhibition of the indexical or associative automaticity. [START_REF] Deacon | The symbolic species. The co-evolution of language and the human brain[END_REF] formulates it as follows: "The prefrontal cortex helps us inhibit the tendency to act on simple correlative stimulus relationships and guides our sampling of alternative higherorder sequential or hierarchic associations." (p. 265).

Different observations are in line with this proposition (cf. [START_REF] Deacon | The symbolic species. The co-evolution of language and the human brain[END_REF]. First, it is most probably because of the lack of a substantial prefrontal cortex that other primates never really get access to symbolic language. Moreover, prefrontally damaged patients are characterised by a disturbed 'flow' of ideas and word choices, not to mention a sort of 'concreteness' in the interpretation of sentence meaning (p. 267). Finally, of all neocortical areas the prefrontal cortical area is the last one to become physiologically and functionally mature in children. This maturation delay is possibly in line with the language acquisition progresses seen in normal language development.

At a local neurolinguistic level too, prefrontal cortical functioning seems a good candidate. Indeed, it seems that the Broca area and the other prefrontal cortical linguistic areas are concerned with far more language functions than pure motor speech expression. For one thing, Broca's area also functions as the phonological loop of the short term verbal memory system in which speech portions are continuously repeated by subvocal rehearsal in order to stay in memory (Smith, Jonides, Marshetz and Koeppe, 1998). For another, adjacent prefrontal areas (in particular BA 45 and 47) are thought to have an executive role, associated with this verbal memory system: [START_REF] Poldrack | Functional specialization for semantic and phonological processing in the left inferior prefrontal cortex[END_REF] suggest these areas are concerned with the retrieval, the selection and the evaluation of semantic concepts, which are distributed and represented elsewhere in the neocortex. [START_REF] Thompson-Schill | Role of left inferior prefrontal cortex in retrieval of semantic knowledge: a reevaluation[END_REF] state it is not the retrieval of semantic knowledge per se that is associated with activity of the left inferior frontal gyrus but rather the selection of information among competing alternatives from semantic memory. And this is precisely the function that would be needed in order to disconnect both ways of language functioning, as was described earlier.

The Freudian Ego as the Prefrontal Cortical Function

In summary, it is thought that the prefrontal cortex functions as that control system that permits one to switch from an associative, bizarre, incoherent use of language to a sound, communicative, verified and pertinent one. The one remarkable thing now is that this hypothesis is also quite clearly in line with Freud's suppositions as stated in the Project (1895/1995; see also [START_REF] Van De Vijver | Over het statuut van het Ontwerp als psychoanalytische tekst. Inleiding[END_REF]. Indeed, one of the basic assumptions of this work is the difference between so-called primary and secondary processes. Primary processes take place associatively: quantities or excitations automatically follow the most facilitated pathways and are thereby driven by the wishful idea in order to obtain satisfaction. Secondary processes, at the contrary, take place under the inhibiting steering of a central instance, called the 'ego' by [START_REF] Freud | A Project for a Scientific Psychology[END_REF][START_REF] Freud | A Project for a Scientific Psychology[END_REF]. This inhibition is precisely needed to prevent excitations to follow these 'speedways' and to make exploration of other pathways possible. This exploration or 'thinking' is steered by the perceptual image and not by the wishful idea, so that, even if satisfaction might eventually be accessed, the followed pathway nevertheless is verified by the external reality and therefore pertinent given the actual context.

Psycholinguistically, it is in the given context tempting to suppose that whenever language is used associatively, with semantic domains accessed solely upon phonological cues independent of their pertinence in the actual context, and therefore without (or with modified) prefrontal control, primary language processes in the Freudian sense of the term are then taking place. Alternatively, whenever phonological cues only give access to pertinent and verified interpretations, i.e. under inhibitory prefrontal control, then secondary processes are taking place. Indeed, [START_REF] Freud | A Project for a Scientific Psychology[END_REF][START_REF] Freud | A Project for a Scientific Psychology[END_REF] himself considers that dreams and free associative talking are primary processes, which is of course in line with the here cited examples. Moreover, he considers the ego, which needs some time to get formed, as the instance permitting a switch from primary to secondary processes and claims it does so by exhibiting a restraining influence. As indicated higher, this again is in line with the supposition that the ego should be seen as the prefrontal cortical influence, with its relatively late maturation in development and its predominant inhibitory influence.

In conclusion, it is suggested that, whenever the signifier, as an empty position with its pertinent restriction labels, interferes in the free access from phonology to semantics, language functions as a predominant secondary process under the inhibitory control of the prefrontal cortex. Alternatively, it is suggested that whenever the signifier, as an articulated phoneme structure, has a free associative access to multiple semantic domains, language functions as a predominant primary process with a lowered level of inhibitory prefrontal control.

Signifiers as Anticipatory Programs in Dreams

We started this argument with some dream observations: dreams were therefore used as the paradigmatical examples of primarily phonetically driven language in this study. The question we now come to is: why do primary processes take place in dreaming? How is this to be situated at a functional level, or even at an evolutionary level?

A sound speculative answer to this question might be found in Winson's work (1990). [START_REF] Winson | The meaning of dreams[END_REF] reports that a typical component of the electroencephalogram (EEG) -the theta rhythm -is observed both in awake animals when they are behaving in particular ways and in sleeping animals during Rapid Eye Movement (REM) sleep. The authors describes the particular behavior in which the theta rhythm is observed as "that behavior that is most crucial to the species survival but that is not genetically encoded since it requires a response to changing environmental information". Examples of this kind of behavior are predation in cats, apprehension in rabbits and exploration in rats. Moreover, it seems that this theta rhythm originates from the hippocampus and that it reflects the settling of long-term memory processes so as to consolidate strategically important acquired motor patterns (cf. [START_REF] Winson | The meaning of dreams[END_REF]. Therefore it is speculated that dreams in these animals should represent "practice sessions" in which animals hone survival skills.

Winson 's results correlate with multiple other dream research results indicating a process of human memory consolidation to be strongly dependent on REM sleep (for a recent review, see [START_REF] Hobson | Dreaming and the brain: Toward a cognitive neuroscience of conscious states[END_REF]. If language should be considered as human's most typical behavior, which is not genetically encoded since it requires a response to changing environmental information, then it is to be expected that speech motor patterns are reiterated during dreams so as to consolidate speech memory. The hypothesis therefore is that it is primarily the phonemic structure that is the material of brain processes during dreams, this is the motor articulatory program. It is thus speculated that it is this phonemic structure, which is neurophysiologically considered the strategic pathway to be consolidated, much apart from every possible semantic interpretation. Semantic interpretations with their impressive imaginary elements as known from dreams, are then considered to be secondary to the central motor of the dream, namely the articulatory programs. Since dreams are not communicative events and therefore need not to be under lexical control, there is no need for prefrontal cortical steering. It is indeed seen that in dreams a relative prefrontal cortex deactivation is measured, which is much in line with the present hypothesis [START_REF] Hobson | Dreaming and the brain: Toward a cognitive neuroscience of conscious states[END_REF]. Semantic interpretation without any lexical or prefrontal steering is expected to result in phonological errors, e.g. mistakenly interpreting 'soul' as 'sole', and this now is exactly what is observed in dreams, as illustrated in the introduction. In conclusion, dream bizarreness is in this context explained as resulting from a primary process in which phonological fragments can gain access to multiple semantic domains with their associated imagery and are thereby not restricted by lexical inhibitory processes. As a consequence, in working with dream material in clinical contexts it is suggested that attention should be paid to the literal structure of the dream narrative as told by the dreamer.

2. 1

 1 The Signifier as the Phonological Form of the Language 2.1.1 Signifiers are Saussurian Phoneme Structures.


Nassim Mrabti
email: nassim.mrabti@u-picardie.fr

Mohamed Amine Gargouri
email: mohamed.amine.gargouri@etud.u-picardie.fr

Nadia Hamani
email: nadia.hamani@u-picardie.fr

Lyes Kermad
email: l.kermad@iut.univ-paris8.fr

Towards a Sustainable Collaborative Distribution Network 4.0 with Blockchain Involvement

Keywords: Horizontal collaboration, Blockchain, Distribution Network Design Problem, Multi-objective optimization

This paper addresses the problem of designing a collaborative 4.0 distribution network using blockchain to ensure coordination between partners and the secure transfer of transactions. In this study, we compare the performance of horizontal collaboration and that of non-collaboration in terms of sustainability. The economic level is considered by the reduction of the logistics costs, while the environmental level is evaluated by the reduction of CO2 emissions from vehicles through their use and depreciation as well as those from the hubs' operation and construction. The social level is addressed by maximizing the created job opportunities and by reducing the accident risk and the noise level. Both mono-and multi-objective optimization approaches are proposed to solve the problem of exact and meta-heuristic optimization using the genetic algorithm and the NSGA-II. The obtained results show that horizontal collaboration is more efficient and promising at all levels.

Introduction

The consideration of sustainability in the distribution network design problem is becoming a necessity for companies to participate in the social life and the preservation of a habitable planet. In economic terms, distribution costs and customer demands are increasingly high. On the other hand, in environmental terms, companies are becoming obliged to participate in the protection of the environment, particularly by reducing the greenhouse gas emissions generated by their distribution activities. Indeed, a carbon report may be required for some companies, which affects their brand image. In social terms, the distribution of goods, particularly by road, produces significant noise pollution and results in a large number of road accidents. Companies cannot overcome these challenges alone, hence the importance of collaboration. In the literature, there are two main types of collaboration, namely Vertical Collaboration (VC) and Horizontal Collaboration (HC). The first type is between partners of the same supply chain and is mainly limited to the information sharing. However, the second type takes Mrabti N., Gargouri M.A., Hamani N., Kermad L. (2021) Towards a Sustainable Collaborative Distribution Network 4.0 with Blockchain Involvement. In: Camarinha-Matos L.M., Boucher X., Afsarmanesh H. (eds) Smart and Sustainable Collaborative Networks 4.0. PRO-VE 2021. IFIP Advances in Information and Communication Technology, vol 629. Springer, Cham. https://doi.org/10.1007/978-3-030-85969-5_4 place between partners of different supply chains [START_REF] Mrabti | A sustainable collaborative approach to the distribution network design problem with CO2 emissions allocation[END_REF]. The majority of studies focused on vertical collaboration whose performance can be further improved with HC [START_REF] Aloui | Systematic literature review on collaborative sustainable transportation: overview, analysis and perspectives[END_REF]. The horizontal collaboration, also called "pooling", consists in sharing means and resources. It not only reduces costs, but also helps to find a trade-off between sustainability considerations and competitive priorities. In this paper, we focus on the collaborative distribution network design problem under sustainability consideration.

The rest of this paper presents the literature review, in Section 2. Section 3 contains the problem description, while Section 4 presents the resolution approaches. Section 5 provides a brief conclusion and some perspectives.

Literature Review

Collaborative distribution network design problem aims at reorganizing or modelling a pooled network by sharing means and resources between partners. It is one of the decision-making strategies that concerns the general direction of the company and involves long-term decisions. Its main objective is to consolidate the logistics flows of different supply chains. Despite its importance, collaborative network has been rarely studied in the literature [START_REF] Mrabti | A sustainable collaborative approach to the distribution network design problem with CO2 emissions allocation[END_REF], [START_REF] Aloui | Systematic literature review on collaborative sustainable transportation: overview, analysis and perspectives[END_REF].

The collaborative distribution network design problem aims at finding the optimal locations of hubs, assigning nodes to hubs, determining the links between hubs and routing flows through the network. Verdonck [START_REF] Verdonck | Analysis of collaborative savings and cost allocation techniques for the cooperative carrier facility location problem[END_REF] considered the two-echelon distribution network that includes depots, distribution centers and customers. The problem was modelled in mixed integer linear programming (MILP). It consists in opening a subset of the distribution centers (DCs) associated with the cooperating partners and determining the optimal assignments between the different nodes. This was achieved by minimizing the costs of transport and operations in the DCs. In addition, Tang et al. [START_REF] Tang | Network design of a multi-period collaborative distribution system[END_REF] examined the same problem over a multi-period horizon. The authors proposed a MILP to minimize the costs of transporting goods and handling regional DCs. They demonstrated that as the number of facilities increased, the transportation cost decreased. This conclusion is not valid when installation costs are considered. Furthermore, Hacardiaux et al. [START_REF] Hacardiaux | Balancing partner preferences for logistics costs and carbon footprint in a horizontal cooperation[END_REF] introduced a mixed integer conic quadratic programming (MICQP) to examine the collaborative location inventory problem (LIP). The model aims at determining the number and locations of the shared DCs, assigning nodes and specifying the size of shipments and inventory levels. These objectives were achieved by minimizing the costs of transport, storage, ordering and installation of DCs as well as by reducing CO2 emissions from transport. Moreover, Fernández and Sgalambro [START_REF] Fernández | On carriers collaboration in hub location problems[END_REF] addressed the collaborative location routing problem (LRP) by proposing a MILP to minimize the freight distribution costs. The obtained results showed that more significant savings can be achieved, compared to the traditional non-cooperative strategies. In the same context, Ouhader and El kyal [START_REF] Ouhader | Assessing the economic and environmental benefits of horizontal cooperation in delivery: Performance and scenario analysis[END_REF] considered the 2E-LRP in a collaborative context by minimizing the costs and CO2 emissions of freight transport. Furthermore, Mrabti et al. [START_REF] Mrabti | The pooling of sustainable freight transport[END_REF] studied the design of a two-echelon distribution network by evaluating logistic costs, CO2 emissions, accident risk and noise level. Recently, Aloui et al. [START_REF] Aloui | Assessing the benefits of horizontal collaboration using an integrated planning model for two-echelon energy efficiency-oriented logistics networks design[END_REF] investigated the collaborative location inventory routing problem (LIRP) by developing a MILP to reduce costs and CO2 emissions in a two-echelon distribution network.

In summary, most studies have focused on the economic dimension through the reduction of logistics costs, especially those generated by freight transport. Recent studies have started to take into consideration the environmental level by reducing CO2 emissions due to transportation. Unlike recent studies, this paper focuses on the collaborative distribution network design problem by considering the three dimensions of sustainability. The economic sustainability is performed by the reduction of logistic costs caused by transportation, storage, hubs opening, handling and penalty due to delivery delay. At the environmental level, we do not limit ourselves to the reduction of CO2 emissions due to transport, but we also minimize the CO2 emissions due to the depreciation of vehicles and those due to the operation and construction of hubs. At the social level, the distribution of goods has a positive impact on the creation of new jobs. Therefore, we maximize the created job opportunities. In addition, we minimize the negative effects on the inhabitants, especially the accident risk and the noise level.

Problem Description

In this section, we describe the model objectives, the importance of using blockchain, the discussed scenarios and the evaluated indicators.

Objectives of Mathematical Models

The envisaged distribution network consists of suppliers who collaborate to deliver their products to retailers through shared hubs : warehouses and distribution centers. The objectives are to determine the number, locations and capacities of hubs as well as to establish the links between the distribution network nodes. The developed models help also determining the quantities delivered in each period in the three parts (upstream, midstream and downstream), the inventory levels in the warehouses, the delayed quantities as well as the number and type of the used vehicles. In this paper, the performance of a collaborative scenario (see Figure 1) is compared to that of a noncollaborative scenario where each supplier is independent of the other in transportation and storage.

To ensure economy of scale, delivery is performed by a heterogeneous fleet of vehicles. This is consistent with the same approach used in [START_REF] Hu | Joint design of fleet size, hub locations, and hub capacities for third-party logistics networks with road congestion constraints[END_REF]. On the other hand, this choice is beneficial for both scenarios because it helps choosing the appropriate type of vehicle for each shipment, which allows improving the fill rate and consequently reducing the total travelled distance. Furthermore, we assume that the retailers' demands are planned over a time horizon (weeks) because several researchers demonstrated the relevance of multi-period planning over static planning [START_REF] Alumur | Multi-period hub network design problems with modular capacities[END_REF].

Importance of Using Blockchain

One of the main obstacles that prevents the success of the horizontal collaboration is the coordination between competing partners, especially information sharing. Typically, the partners use electronic data interchange (EDI) systems to exchange information. However, this data is frequently transmitted in batches rather than in real time. It is therefore likely that a shipment may disappear or not be updated. It is also possible that some collaboration partners may not receive this information till the release of the next EDI package. The use of the blockchain helps overcoming this problem as the information will be updated regularly and can be quickly distributed to all the involved entities.

The blockchain is a decentralized database which represents a powerful solution for all members of the collaborative network to access in a secure and fast way. The use of blockchain enables real-time traceability throughout the collaborative distribution network. The blockchain ensures a secure exchange of monetary values and information, leading to a new cooperation between supply chain entities along the delivery chain [START_REF] Chen | A Blockchain-Driven Supply Chain Finance Application for Auto Retail Industry[END_REF]. This represents a way to provide customers with additional information about products and processes. Information transparency becomes a source of competitive advantage that allows companies to differentiate themselves from their competitors and build a responsible and trustworthy brand reputation [START_REF] Macchion | The Implementation of Traceability in Fashion Networks[END_REF].

Sustainability is becoming a key factor in efficiency and profitability. The use of blockchain promotes sustainable practices within distribution networks. At the economic level, the use of blockchain allows trading while avoiding fraud or opportunistic behavior [START_REF] Tan | A Blockchain-Based Framework for Green Logistics in Supply Chains[END_REF]. Blockchain solves several problems such as: real-time communication, fast payment with reduced product costs, and reduced delivery times. In addition, improved transparency allows for better resource management by minimizing waste and thus reducing distribution costs. Blockchain is a great way to manage inventory, accounting, asset scheduling and customer transactions. At the environmental level, tracing products from their origin to the end consumer reduces carbon footprints and unsustainable practices. Indeed, it will be possible to identify in real time the vehicles that emit the highest quantities of CO2 emissions, which facilitates the implementation of sudden measures. In addition, driver behavior can cause adverse impacts on the environment. According to [START_REF] Varriale | The Unknown Potential of Blockchain for Sustainable Supply Chains[END_REF], using token-based blockchain to reward eco-driving can encourage the driver to anticipate and protect the environment. Furthermore, drivers are usually only paid when they travel specific distances, resulting in unsustainable practices caused by acceleration. It is possible to combine blockchain with smart contracts to pay the driver in real time, which motivates him to maintain his performance [START_REF] Varriale | The Unknown Potential of Blockchain for Sustainable Supply Chains[END_REF]. Blockchain also allows for the control of dangerous waste, distributing responsibility to system participants. At the social level, blockchain can help respect human rights. Indeed, the transparency of blockchain is a way to control companies in violation of working hours limits, child labor and inhumane working conditions. By combining IoT (Internet of Things) and blockchain, it is possible to analyze data that relates to workplace health and safety, namely lighting, temperature, humidity, noise and ventilation. This data can be used to improve the working condition and comfort of workers.

Suppliers

Warehouses DCs Retailers

Blockchain

Exchange of Information flows in real time

Exchange of financial flows in real time In this sense, we assume that information flows and financial flows are managed by the blockchain (see Figure 2). It allows the transition from the traditional distribution network to the distribution network 4.0 by exchanging data and managing monetary transactions.

Examined Scenarios

As noted above, in this study we examine two scenarios:

Non-collaborative scenario (NCS): It refers to the initial situation, without collaboration between suppliers. In this scenario, each supplier delivers its goods to its own retailer through a warehouse and a distribution center.

Collaborative scenario (CS):

In the collaborative scenario, suppliers deliver their goods to the shared warehouses. Flows are massified in the warehouses and distribution centers, which makes it possible to optimize the vehicle fill rates by grouping goods. In this scenario, we assume that each supplier and each retailer are assigned to a single warehouse and a single distribution center, respectively. This assumption reduces the shipping costs as it is less expensive to ship a larger quantity to a single hub than to ship smaller ones to more than one hub. It also facilitates warehouse management. To ensure the flow of all products throughout the distribution network, we assume that a warehouse is assigned to several distribution centers and vice versa.

Sustainability Indicators

The sustainability is now among the top ten unresolved global concerns and still attracts much attention. It was first described by the World Commission on Environment and Development as the "development that meets the needs of the present without compromising the ability to meet the needs of future generations". Sustainability maintains a balance between the economic, environmental and social objectives, which is also called the triple bottom line of sustainability (People, Profit, Planet). Generally, the economic level concerns the increase in traffic congestion leading to loss of time, transport inefficiencies, unreliable delivery to the recipient, resource use and logistics costs. On the other hand, the environmental level is mainly related to CO2 emissions, use of non-renewable resources, waste and loss of green space. However, the impact of freight distribution on the social level can be positive ( such as increasing created job opportunities) or negative (e.g. rising accident risk and noise level). Sustainability can be achieved only by considering and combining all three dimensions.

In this sense, designing a collaborative distribution network with economic, environmental and social sustainability is a critical and urgent issue. To this end, we used the indicators presented in Table 1 to design a sustainable distribution network.

The following parameters are used to model the sustainable indicators 𝑑 𝑖,𝑗 : the travelled distance between nodes i and j 𝐶 𝑜𝑣 , 𝐶 𝑞𝑣 : the unit costs of transport by an empty and fully loaded vehicle v, respectively 𝐸 𝑞𝑣 , 𝐸 𝑜𝑣 : the unit CO2 emissions due to transport by an empty and fully loaded vehicle v, respectively 𝑄 𝑣 : the vehicle capacity v 𝑞 𝑖,𝑗,𝑝,𝑣,𝑡 : the quantity of product p transported between two nodes i and j by the vehicle v in the period t 𝑀𝐸 𝑣 : the CO2 emissions due to the manufacturing of the vehicle v 𝑆𝐿 𝑣 : the service life of the vehicle v 𝑁 𝑚 : the number of needed jobs to handle 100 pallets 𝑇𝐶 𝑖,𝑗,𝑣,𝑡 , 𝑇𝐸 𝑖,𝑗,𝑣,𝑡 : the costs and CO2 emissions caused by transport between two nodes i and j through a vehicle v in period t, respectively 𝐽𝑂 𝑚,𝑡 : the created job opportunities by the opening of hub m in period t

The economic level is ensured by reducing the costs of freight transport, storage, handling, delivery delay and the establishment of the hubs. Minimizing the transportation cost guarantees the massification of flows. Indeed, it allows choosing the type of vehicle to be used as well as the quantity of goods to be delivered in each period and assigning the non-hubs nodes to the hubs [START_REF] Mrabti | The pooling of sustainable freight transport[END_REF]. The transportation cost is given by Equation (1) adapted from [START_REF] Pan | The reduction of greenhouse gas emissions from freight transport by pooling supply chains[END_REF]. It depends on the travelled distance di,j between nodes i and j, the unit transport costs Cqv and Cov, the vehicle capacity Qv, the quantity of transported goods qi,j,p,v,t and the number of vehicles multiplied by two to consider the empty return. The reduction in the storage cost allows not only minimizing the stock itself, but also decreasing the storage risk, resource management and the operation of hubs. In addition, it means frequent delivery of goods, which improves the service level. In fact, the fixed handling cost includes the costs related to sorting, loading and unloading of goods. The penalty cost is imposed in case of delay in delivering the requested quantity at the right time. The last evaluated cost is that of establishing hubs. The reduction of this cost ensures not only the reduction in the number of hubs but also the adjustment of the surface of each built hub.

Regarding the environmental level, we do not limit our study to CO2 emissions due to the freight transport, unlike previous studies. But, we evaluate those generated by the depreciation of vehicles, the operation and the construction of hubs. The CO2 emissions due to transport is given by Equation ( 2) that is similar to that of the transport cost by replacing unit costs by unit emissions Eqv and Eov. The CO2 emissions caused by the depreciation of vehicles are given by Equation (3). They depend on the total travelled distance multiplied by the emissions due to the manufacturing of the vehicle MEv and divided by its service life SLv.

Socially sustainable goal is also an indispensable criterion that has received insufficient attention in previous studies. In this paper, it is attained by maximizing the created job opportunities and reducing the accident risk and the noise level caused by the freight distribution. Indeed, the automation of hubs affects negatively the created employment opportunities. On the other hand, high unemployment can lead to social instability and a negative multiplier influence. This indicator, given by Equation ( 4), depends mainly on the quantities of goods entering each hub and the number of needed jobs Nm to handle 100 pallets. This number depends, in turn, on the type of hub (automated, semi-automated and fully automated). Indeed, the number of created jobs decreases with the increase in the number of automated hubs. In addition, the distribution of goods has negative effects on the human health and road safety that should be reduced.

Optimization Approaches

The developed mathematical models were applied on a distribution network of France and solved, in an exact way, for small size problems and, by metaheuristics, for large size problems.

Exact Optimization

The exact optimization was performed by the CPLEX solver. First, the mono-objective optimization was carried out by minimizing the logistic costs and the CO2 emissions as well as by maximizing the created job opportunities. Second, to find a good compromise between the three objectives, the ε-constraint method was used. It consists in optimizing one of these objectives by putting the others under constraints. In addition to its simplicity, this method does not require imposing additional variables on the mathematical model. Furthermore, it does not require a common scaling since it allows each objective function to be represented by its own scale.

In our study, the economic level was considered as the objective, while the other two levels were treated as constraints. This choice is justified by the fact that this level takes into account more indicators than the other two levels. The accident risk and the noise level were evaluated after the resolution of models. The considered case study concerns a distribution network in France containing a list of suppliers who collaborate to satisfy their customers through shared hubs. The Figure 3 represents an example of a distribution network obtained by minimizing CO2 emissions. This network includes 7 suppliers, 7 warehouses, 7 distribution centers and 13 retailers.

Heuristic Optimization

Exact resolution is a critical issue when dealing with a large problem. For this reason, both genetic algorithm and NSGA-II were developed to perform mono-objective and multi-objective model optimization.

Mono-objective optimization. The choice of the genetic algorithm (GA) is justified by the fact that it has shown excellent performance in solving various optimization problems. This algorithm allows to obtain efficient solutions in terms of gap. The GA imitates three genetic operations on a certain base population such as selection, mutation and crossover. The first operation plays an important role in determining the quality of the new generations. The selection can be done by tournament, roulette wheel or uniformly. The mutation operator allows the GA to better browse the search space by inflicting a modification in a gene. The crossover operator aims to increase the diversity of the population by manipulating the structure of the chromosomes.

The efficient implementation can be ensured and the enhancement of GA can be achieved only by the well choosing the optimal parameters of this algorithm. For this reason, this algorithm was run several times by varying its parameters. The best size of population for this algorithm is 150 that gave the best results in terms of cost (see Figure 4). The results of the population size parameterization npop in the collaborative scenarios were obtained for multi-point crossover and swap mutation probabilities equal to pc=0.85 and pm=0.3, respectively. The results of the economic monoobjective resolution are represented in Table 2. The latter shows that the horizontal collaboration led to significant reduction in costs and CO2 emissions and an increase in created job opportunities. The noise level and the accident risk are also improved compared to the non-collaborative scenario. npop Multi-objective optimization. In multi-objective optimization, we applied the NSGA-II algorithm proposed by Deb et al. [START_REF] Deb | A fast and elitist multiobjective genetic algorithm: NSGA-II[END_REF]. This choice is motivated because this algorithm has proven its efficiency in terms of the number of Pareto optimal solutions. It is a fast and elitist non-dominated sorting algorithm that manipulates a population of individuals and uses an explicit diversity preservation mechanism. Its objective is to randomly generate a population P0 of N solutions (or individuals) and rank them according to the dominance principle. Figure 5 shows the multi-objective results obtained in the collaborative scenario. As the result of the created job opportunities is comparable in the two scenarios, we presented, by a color scale, the results obtained using NSGA-II to minimize logistic costs, CO2 emissions, noise level and accident risk. Each point on the graph represents a solution to the multi-objective problem. However, choosing a solution that offers a particular optimal trade-off is not a trivial task, and interpreting a 3D Pareto front is very difficult. Nevertheless, the points in the middle of the graph turn out to correspond to the optimal solutions that offer a good compromise between the four objectives. On a practical level, decision makers can choose one of these solutions by negotiating among themselves.

Conclusion and Perspectives

In this study, we addressed the collaborative distribution network 4.0 design problem under sustainability considerations. Based on a list of economic, environmental and social sustainability indicators, we compared the performance of collaborative scenario to that of the non-collaborative scenario. Mono-objective solving was performed by the CPLEX solver and the genetic algorithm, while multi-objective resolution was done using the ε-constraint method and the NSGA-II algorithm for large problems. To address the challenges of implementing collaboration, we assumed that information exchange and monetary transactions are carried out through the blockchain. The obtained findings showed that horizontal collaboration achieved notable results, compared to the non-collaborative scenario. As a perspective, we will present a framework on the involvement of blockchain and IoT in collaborative distribution networks. We will also combine multi-criteria analysis methods with metaheuristics to select solutions offering a good compromise between different objectives.

Fig. 1 .

 1 Fig. 1. Examined collaborative scenarios.

Fig. 2 .

 2 Fig. 2. Implication of blockchain in the collaborative distribution network.

Fig. 3 .

 3 Fig. 3. Example of a distribution network (minimization of CO2 emissions).

Fig. 4 .

 4 Fig. 4. Variation of costs according to the number of generated populations (CS).

Fig. 5 .

 5 Fig. 5. 3D Trade-off solutions obtained by solving CS using NSGA-II.

Table 1 .

 1 Evaluated sustainable indicators.

	Economic level	Environmental level	Social level
	-Transportation cost	-CO2 emissions dues to vehicles :	-Created job
	-Storage cost	transportation and depreciation	opportunities
	-Handling cost	-CO2 emissions due to hubs : operation	-Accident risk
	-Penalty cost	and construction	-Noise level
	-Establishment cost

Table 2 .

 2 Results by the mono-objective optimization.

		1,46E+07
	(€)
	Costs	1,44E+07
		1,41E+07
		0	75	150	225	300	375	450	525
		Sustainable indicators		NCS Exact CS Exact GA
		Costs (10 6 €) CO2 emissions (10 5 kg CO2)	14.49 34.00		14.19 31.80	14.32 32.40
		Job opportunities created (JO) 792 Noise level (10 3 dB) 24.506		889 15.604	881 15.562
		Accident risk reduction rate (%) 15.02%		20.03% 19.88%


Lya Fontaine

Karine Isoird

Josiane Tasselli

Emmanuel Scheid

Patrick Austin

Alain Cazarre

Riadh Issaoui

Fabrication and characterization of Si3N4-MIS structures on p-type diamond

à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

With its wide bandgap and interesting electronic properties, diamond is a promising material for high power applications. However, several technological obstacles have to be overcome to develop MOS diamond devices. In this context, we study the fabrication of MIS structures based on the deposition of a Si 3 N 4 -dielectric layer. The C(V) measurements are presented and the interface between diamond and Si 3 N 4 is analyzed.

MIS structures are fabricated on a P -/P + stack on (100) diamond at LSPM laboratory with doping estimated to be [B] = 1x10 17 at.cm -3 /[B] = 1x10 20 at.cm -3 for 4µm/10µm thicknesses respectively.

The diamond layers surface is chemically cleaned and treated using Ozone UV to ensure the elimination of contaminants and C-H bonds in order to limit the number of traps at the interface between diamond and the dielectric layer.

A 30nm-Si 3 N 4 layer is deposited by LPCVD at 770°C. Ohmic contacts using Ti/Pt/Au are fabricated on the P+ layer and Al contacts (of a diameter of 300µm, 200µm and 100µm) were deposited on the dielectric layer.

The module and argument variations of the impedance are then measured. These characteristics show the capacitive behavior of the structures over a wide frequency range, from 1 kHz to 100 kHz. The influence of the diamond p-layer resistivity is therefore negligible.

A two-element model (capacitance and resistance in parallel representing leaks) is therefore used hereafter.

C(V) measurements show the different modes of accumulation, depletion and deep depletion. Comparison between measurement and to the theoretical curve calculated from the model of the ideal MIS device highlights the presence of a significant number of traps.

The development of these functional MIS structures opens the way to the manufacturing of diamond power MOS devices, even if a limitation of the traps is still necessary.

  Fabrication and characterization of Si 3 N 4 -MIS structures on p-type diamondLya FONTAINE 1 , Karine ISOIRD 1 , Josiane TASSELLI 1 , Emmanuel SCHEID 1 , Patrick AUSTIN 1 , Alain CAZARRE 1 , Riadh ISSAOUI 2 1 LAAS-CNRS Université de Toulouse, CNRS, UPS, Toulouse, France 2 LSPM Université Paris 13, Villetaneuse, France

	Key words: MIS structure, MOS power devices, Si 3 N 4