Keith Dixon

New Labour and Devolution: radicalism or bricolage?

Keywords: Nationalisme écossais et gallois, dévolution, néo-travaillisme

This paper argues that New Labour's devolution proposals can be seen as part of a strategy of « political distinction » from the Conservative party, all the more necessary as there had been a conspicuous convergence in most other policy areas. After retracing the history of Labour attitudes towards Home Rule on the periphery of the United Kingdom in the XXth century, the paper focuses on the contemporary period, suggesting that Thatcherism was perceived as an "alien" doctrine in both Scotland and Wales, thus hardening the resolve of a significant part of the population to loosen or break the old constitutional ties. It is against this background that New Labour's positioning as the party of movement is discussed. It is argued that, in Scotland, two factors contributed to making constitutional reform unavoidable from the 1980s on : a major shift in favour of Scottish autonomy in both the cultural and intellectual fields and the creation of a "popular front" in favour of constitutional reform in the shape of the Scottish Constitutional Convention. The paper concludes on a discussion of the contrasting positions of Vernon Bogdanor and Tom Nairn of the state that the United Kingdom is in today.

Résumé

Cet article considère que les propositions de réforme des néo-travaillistes concernant la dévolution doivent être appréhendées comme faisant partie d'une stratégie de « distinction politique » par rapport au parti conservateur, rendue d'autant plus nécessaire par la forte convergence dans la plupart des autres domaines. Après avoir retracé l'évolution du positionnement travailliste sur la question de l'autonomie de la périphérie britannique au cours du XXe siècle, l'analyse se centre sur la période contemporaine. Au cours des années quatre-vingt, le thatchérisme est de plus en plus perçu, en Ecosse comme au pays de Galles comme une doctrine étrangère (aux traditions politiques et philosophiques de ces deux pays), et cette perception renforce la détermination d'une partie de la population de desserrer, voire de rompre les vieux liens constitutionnels. C'est en tenant compte de cette contrainte, que l'on doit analyser le nouveau positionnement des travaillistes comme le parti du mouvement constitutionnel. Deux facteurs en Ecosse ont rendu la réforme constitutionnelle difficile à éviter pour les néo-travaillistes: un changement significatif en faveur de l'autonomie dans les champs intellectuel et culturel et la construction d'un « front populaire » en faveur du changement, sous la forme de la Convention Constitutionnelle Ecossaise. L'article se termine avec une discussion des positions divergentes sur cette question de Vernon Bogdanor et de Tom Nairn.

Introduction

If the Labour party became New Labour with the arrival of Anthony Blair as leader in 1994, the process of transformation which led to and accelerated under New Labour began -most observers would agree -a decade earlier. With 28.3% of the vote in the general election of 1983 the Labour party registered its lowest score since the introduction of full adult suffrage in 1918. This was the alarm signal that was to trigger, under the successive leaderships of Neil Kinnock, John Smith and Anthony Blair, the process which is often described in both the hagiographic and the academic literature on the subject as the « modernization » of the Labour party and its policies. As I have explained at length elsewhere [START_REF] Dixon | Un Digne Héritier[END_REF][START_REF] Dixon | La Mule de Troie, Bellecombe-en-Bauges : Editions du Croquant[END_REF][START_REF] Dixon | Un Abécédaire du Blairisme, Bellecombe-en-Bauges : Editions du Croquant[END_REF] I would prefer the notion of « conspicuous convergence », as developed among others by Colin [START_REF] Hay | The political economy of New Labour. Labouring under false pretences[END_REF], to the modernization thesis1 which has become part of the Blairites' (now jaded) self-image. From the mid-eighties on, the leadership of the Labour party, when faced with the on-going successes of the Thatcher governments, adopted a policy of gradual accommodation with the new policy mix that had been introduced by the radical Conservatives, thus creating a new « common sense » of government. This process of policy accommodation was to be more publicly proclaimed and more explicitly theorized under the new New Labour leadership, with some considerable help from Anthony [START_REF] Giddens | Beyond Left and Right[END_REF][START_REF] Giddens | The Third Way[END_REF], first among others in what had become the New Labour organic intelligentsia. By 1996, when Blair published his first collection of speeches and newspaper articles as Labour leader, entitled New Britain. My vision of a young country, the contours of New Labour economic and social policy were relatively plain to see, for anyone willing to read through Blair's not always inspiring prose and look beyond the rhetorical gimmicks. The paradigms of economic and social management of Britain that had been introduced by Margaret Thatcher, which included a large degree of privatization, flexible labour markets, a reformed and wealthy-friendly fiscal structure and a legally constrained trade union movement, would be kept by an incoming Labour government. The reality of New Labour government since 1997 has given ample proof that Blair's promises have been kept, sometimes quite zealously so. Privatization has continued in one or other of its various forms (the dominant one being that which was borrowed from John Major in the form of the Private Finance Initiative -now rebaptized Public-Private Partnerships); labour market flexibility is considered to be so important that successive New Labour Foreign Ministers have insisted on its serving as a model for the rest of archaic Old Europe 2 ; Britain continues to be a low-tax regime, and to attract capital and labour for that reason; if the trade unions have seen their legal situation somewhat improved (with the right to trade union organization in the workplace now officially recognized) there has been no return to the trade union rights of the pre-Thatcher period, and the leader of New Labour has regularly shown his distaste for traditional forms of trade union action and adopted a rhetoric more familiar within the Conservative tradition when confronted with striking workers. Similarly, in the area of foreign policy the path followed by New Labour has been one of sometimes spectacular convergence around policies initiated by successive American presidents, Democrat and Republican, thus transforming the relatively novel and much discussed ideological proximity between Margaret Thatcher and Ronald Reagan into a model of contemporary Anglo-American relations. The policy convergence between the New Thatcherite Right and New Blairite Labour has been such that the title of Simon Jenkins' recent book on the relationship between M. Thatcher, J. Major, A. Blair and G. Brown -Thatcher and Sons (2006) -seems much more flatly descriptive and much less provocative than the author no doubt hoped. Given this extraordinary convergence, the problem for New Labour, at least in the early years of its rise to power, has been how to demarcate itself in this relationship of ideological fellow travellership with Conservative neoliberalism. I will suggest here that devolution, and more generally constitutional reform, have been one of the major elements in what we might like to call New Labour's strategy of political distinction. Although in the areas of economic, social, penal and foreign policy the divergence between the two major parties has been a matter of what Freud described in another context as « the narcissism of minor differences » Conservative and New Labour attitudes towards constiutional reform over the last twenty years have been strikingly at odds with each other.

Labour, old and new, and the National Question

There were no particular reasons why this should be so. Both parties had come to see the British union as the only viable framework in which to operate effectively. The Conservatives had of course been more vocal in their opposition to any form of Home Rule from the late XIXth century on. In their early manifestations the labour movement and the first political organizations to emerge from that movement were in favour of the demands for Home Rule expressed forcefully in Ireland and less so in Scotland [START_REF] Harvie | Before the Breakthrough, 1886-1922[END_REF]). However, by the 1920s there is an observable parting of the ways between the Home Rulers and the socialists, with some notable exceptions (one thinks of Roland Muirhead in Scotland, for example). In the inter-war period in both Scotland and Wales, not to mention England, the demands for recognition of national particularities in the cultural and political fields seemed at best an irritation as class issues came to the fore. The ambiguity, in political terms, of the nationalist movements in both Scotland and Wales, the propensity for certain of their leaders to lean heavily towards the Right and to manipulate the dynamite of xenophobia were to confirm many Socialists in their hostility towards vociferous small-nation nationalism (Saunders Lewis was a some time admirer of Maurras and Action Française and Andrew Dewar Gibb, the SNP leader of the late Thirties, hated the Irish immigrants in his native land and made no bones about it [START_REF] Dixon | Le nationalisme écossais conservateur dans l'entre-deux-guerres : les idées de Andrew Dewar Gibb et de George Malcolm Thomson[END_REF]. « What a curse to the earth are small nations » proclaimed the revolutionary socialist Scottish novelist Lewis Grassic [START_REF] Gibbon | Glasgow[END_REF](Grassic Gibbon 1934 : 144) and in doing so he was expressing the vigorous rejection of nationalism by many within the labour movement. By the time of the post-war Labour government of Clement Attlee, the Labour party had become in its own way as unionist as its Conservative enemies (to borrow a phrase from Tony Crosland) and this was to continue throughout the period of the post-war social democratic consensus which promised and to some extent delivered a more equal treatment between regions of Britain and guaranteed a minimum social protection for all -including those populations who had still in living memory the inordinate suffering inflicted upon them by the free play of market mechanisms in the South of Wales and West of Scotland during what Kenneth Morgan has described as the « locust years » of the Great Depression (Morgan 2002 : 210-240). The experience of office from 1945 to 1951 and again from 1964 to 1970 no doubt reinforced what had become the doxa within the Labour party, leadership and rank and file included, that only a central British state occupied by Labour could impose redistribution and effectively combat inter-regional inequalities. The Britishness of that central state was indeed more or less taken for granted until the rude eruption of nationalism on the political scene from the late Sixties on. I will not go into any detail about the internal debate (or the lack of such debate) within the Labour party in these crucial years which saw both Plaid and the SNP become substantial political and electoral forces -substantial enough to force both the major political parties into a re-appraisal of the national question. Suffice to say that the Labour party's conversion (or return, if you prefer) to Home Rule during the ill-fated governments of Wilson and Callaghan from 1974 to 1979 was a highly uneven process, one of whose most significant manifestations was a durable tension between a pragmatic/opportunistic leadership, struggling to keep the boat of government afloat through deals in parliament with the Liberals and others, and a party rank-and-file which was very far from enthusiastic about what it perceived as concessions to the Nationalists. This is particularly clear in Scotland where the majority of the party in the seventies continued to see the SNP as Tories in national costume and Home Rule as a diversion from the real tasks at hand.

The Thatcher factor

What changed all this irremediably was the Conservative victory of the 3 rd of May 1979, only a couple of months after the referendum fiasco in Scotland and Wales. Because of the very radicality of Thatcherite policies, largely inspired by the writings of Friedrich von Hayek, that great admirer of English XIXth century economic liberalism, but also because of the growing divergence in the perceptions of Thatcherism between a predominantly enthusiastic England (the populous South of England in particular) on the one hand and an increasingly hostile Scotland and Wales on the other, Thatcherite policies were to prepare the ground for a major shift in public perceptions in both of these two countries (McCrone 1992 ; Brown / McCrone / Paterson 1998). It is indeed during this period that the movement in favour of the recognition of Scotland's national specificities grows in strength, although this is not necessarily reflected in the electoral results of the SNP, which does badly through much of the eighties. Nationalism, or at least the increasingly strident demand that Scotland and Wales should not be submitted to the repeated onslaughts of an alien doctrine and of political practices which were inimical to the dominant traditions of both these countries, was to grow and above all to spread across the boundaries of party politics during this period, perhaps more than ever before. In the Scottish context, I would argue that there are two key factors which were to contribute vitally to creating the conditions in which New Labour was to emerge in the mid-nineties with its proposals for constitutional reform. The first of these is the shift within the intellectual and cultural fields which sees the emergence of a multifarious movement in favour of the critical rethinking of Scotland's place within British history and within the contemporary political and cultural landscape. The second, not-unrelated phenomenon, is the emergence of a popular front of opposition to the constitutional status quo in the form of the Scottish Constitutional Convention (although no doubt some of the more staid members of that august assembly would be unhappy with the idea of them being anything as radical as a popular front). I have no time here to go into the detail of the contribution of Scotland's academics, writers and other cultural producers in the rewriting of Scotland in the 1980s and 1990s and the reactivation/invention of a tradition in which Scotland stood apart in its defiance of the doctrinaire neo-liberalism being implemented down South with increasing fervour as we move through the decade. As Roderick Watson has argued [START_REF] Watson | The Literature of Scotland[END_REF], there is a new flowering of Scottish culture during this period, in which few or any of the major actors are willing to publicly espouse the cause of unionist Conservatism. If we look at the names of the major figures of the period -Alasdair Gray, Jim Kelman, Tom Leonard, Liz Lochhead, Janice Galloway, Jackie Kay, Iain Banks, Willie McIlvanney, they read like a roll call of more or less militant anti-Thatcherism3 .

Similarly in the academic field, a vast amount of work was being carried out to call into question the historical myths of unionism, of which Scottish academia had been a major vector, and to redesign the contours of Scotland's past and present. Cairns Craig's Determinations series at Polygon is one distinguished example among many others of the intellectual vitality of the period. The Series preface was quite clear in its intentions : If the determinations which shape our experience are to come from within rather than from without, they have to be explored and evaluated and acted upon. Each volume in this series will seek to be a contribution to that self-determination; and each volume, we trust, will require a response, contributing in turn to the on-going dynamic that is Scotland's culture. Much of this cultural and intellectual work was to find a strong echo in the vibrant journal and small magazine culture of the period, to which Radical Scotland was a major contributor. In the political field, the Scottish Constitutional Convention grew, sometimes laboriously, out of the Campaign for a Scottish Assembly, but above all out of the growing recognition that a broad coalition of forces in Scotland -from the womens' movement to the local authorities, from the STUC to the Catholic Church, and from the Communists to the Liberals, and crucially including Labour -were opposed to the constitutional status quo and were willing to bury (some of) their differences in order to propose a reasoned programme of constitutional change in face of Thatcherite immobility. No matter what the intentions of one or other of the actors may have been (the Labour desire to isolate the SNP or the Liberals' parallel agenda of reforming an electoral system in which they were systematically under-represented) the creation of the Convention and its input as a collective intellectual into the political debate constituted a major turning point. It thus gave political form to -but also a particular political interpretation of -the mass rejection of Thatcherism which had expressed itself not only in the ballot box in Scotland (and Wales) since 1979 but also in the contribution of the Scots and the Welsh to the major movements against the new faith in the market, in particular the 1984-85 miners strike and the « Can pay, won't pay » campaign against the poll tax in the late eighties4 .

The political inheritance of New Labour

This then is what Anthony Blair inherited when he replaced John Smith at the head of the Labour party in 1994 : a political party still in search of its position within a much changed British political field, now dominated by market thinking, but also a movement whose strengths lay on the periphery where the rejection of Anglo-centrism, in the caricatural form of Thatcher and Major (warm beer and cricket...) was henceforth a force to be reckoned with and which the old incantations about the horrors of tartan Conservatism and separatist Welshness could no longer conjure away. From these two major constraints was to emerge that hybrid creature, Blairism. One must not undersestimate these symbolic constraints when measuring the « statesmanship » of Blair as constitutional reformer after 1997. The dominant group within Blair's New Labour party had no inherent reasons for being more attentive to demands for Home Rule than their immediate forebears. Blair himself had paid little attention to the national question since his election in 1983, and his base in the North East of England did not naturally predispose him in favour of devolution. The new leader was surrounded by Scots -but they had been far from being unanimous in their support of Home Rule in earlier times. Indeed, Robin Cook had been active in his opposition to Home Rule during the 1979 referendum campaign. Although Gordon Brown had moved away from his proximity may have found it more diplomatic to hold their peace during a period of almost unanimous Scottish loathing of radical Thatcherite conservatism.

with Scotland's nationalist-leaning Left radicals of his early Red Paper on Scotland years, he had nonetheless led Labour's first devolution campaign in Scotland. But by the mid-nineties, his preoccupations were no doubt elsewhere as he battled to locate himself at the centre of the New Labour machine. Neil Kinnock, who continued to haunt the corridors of Labour party power and to provide symbolic capital to the New Labour leadership, was himself only a recent convert to devolution, which he had combatted within the Welsh party in the 1970s. No doubt Labour leaders on the periphery, at least in Scotland, were by the mid-nineties obliged to position themselves differently from their Westminster-(or Brussels-) based colleagues, as popular and elite support for constitutional change built up. There is no reason to doubt that some of them, like Donald Dewar, had indeed been won over to the idea of hardy political decentralisation. From a theoretical point of view, however, Labour in its « new » incarnation, although now officially the party of constitutional movement alongside the Liberal Democrats, had made little progress in rethinking the national question and remained as hostile as ever to expressions of nationalism which called into question the centrality or the future of the British state. Thus Anthony Giddens, who has something to say about almost everything in his strangely influential book, Beyond Left and Right (1994), pays scant attention to what he calls « local nationalisms » which he sees as a preoccupying symptom of backward reactions to the globalization process which in the main he embraces as a vector of modernization. Blair's presentation of devolution in New Britain, after the singing the praise of its own modernism, insists on the unionist dimension of Labour's devolution proposals (a position echoed in Scotland by George Robertson) and makes it clear where sovereingty will ultimately lie, even after the transfer of powers has been enacted : « The sovereignty of the UK parliament will remain undiminished ». Nonetheless, and in contradistinction to the devolution proposals of the Wilson-Callaghan period, once in office in 1997 the New Labour machine moved quickly and resolutely to implement its 1997 electoral campaign proposals, carrying an admittedly much-cowed party machine and rank-and-file with it. The devolution proposals -largely inspired as far as Scotland was concerned by the detailed demands of the Constitutional Convention -were rapidly put to the vote through a referendum in September 1997, which showed substantial support for change in Scotland and an as yet lukewarm approval of the creation of a relatively weak assembly in Wales5 . The legislation that was then to lead to the creation of the Scottish parliament and the Welsh assembly in 1999 showed the lengths to which Labour was willing to go to preserve support for its changes. The introduction of proportional representation, in particular, which selfevidently was in contradiction with Labour's immediate interests and condemned the party to coalition government in Scotland, illustrates this quite clearly.

Conclusion: New Labour radicalism or pusillanimous bricolage

In the debate that has accompanied the constitutional reforms of the successive New Labour governments since 1997, two polar positions have emerged. On the one hand, those who see these changes as indicators of the radicality of the New Labour government and of its resolute attachment to modernisation. Vernon Bogdanor is one of the most distinguished representatives of this view. He has argued in a text published at the end of the first New Labour term of government that « The crucial consequence of the reforms of the Blair era, however, is to give us, for the first time in our history, a constitution; and, moreover, a constitution which is quasi-federal in nature. It can hardly be denied that this is a revolutionary change. » (Bogdanor 2001 : 146) This indeed is hardly denied by Peter Mandelson, garrulous as ever, who in his The Blair Revolution Revisited describes Blair's « constitutional revolution » as « the most extensive programme of constitutional modernisation for more than a century -indeed, since the Great Reform Act of 1832 » and adds significantly « which appears to have put to rest the serious nationalist threat in Scotland and, to a lesser extent, in Wales » (Mandelson 2002 : xxii) At the other end of the spectrum, Tom Nairn, in After Britain (2000) and more recently in his introduction to the 2006 re-edition of The Break-up of Britain, has argued that the Canute-like reforms of New Labour are unlikely to hold back the rising tide of nationalism. Nothing more than a clumsy bricolage and a last-ditch attempt to save the unsaveable : Underneath the present charades of apostasy and self-contempt, those deeper currents that have carried the break-up so far are not slackening, but acquiring new force. Just as the tide in favour of home rule built up during the eighteen years of Conservative Unionism, so the new tide seeking real independence is forming itself beneath the façade of Blairism. It will rise into the spaces left by New Labour's collapse, and by the increasing misfortunes of the old Union state. (Nairn 2006 : introduction) Of the two positions, Nairn's seems to be much closer to the real movement of history -indeed there is something strangely unhistorical in Bogdanor's account. As if the massive shift in public and elite opinion, especially in Scotland, in the 1980s and early 1990s, were no more than the background music to Blairite reforms. However, Nairn's own position returns us to a central issue only touched upon earlier in this paper : the fact that the anti-Thatcherite resistance of the 1980s, strong and popular in both Scotland and Wales resulted essentially in a movement in favour of a new constitutional set-up, leaving the rest of the Thatcherite legacy intact. Perhaps Lewis Grassic Gibbon was not entirely wrong when, looking to a self-governing future for Scotland, he stated with heavy irony : It will profit Glasgow's hundred and fifty thousand slum-dwellers so much to know that they are being starved and brutalized by Labour Exchanges and Public Assistance Committees staffed exclusively by Gaelic-speaking, haggis-eating Scots in saffron kilts and tongued brogues full of such Scottish ideals as those which kept men chained as slaves in Fifeshire mines a century or so ago. (Grassic Gibbon 1934 : 146) The labour exchanges and public assistance committees have of course disappeared from neoliberal Scotland, and the forms of domination of the poor have indeed been modernized by New Labour's Welfare to Work programmes. But one might be excused for believing that the underlying issue raised here by Grassic Gibbon remains painfully relevant.

This is best exemplified in the hagiographic literature produced by Blair's inner circle. See, for example, Peter Mandelson, The Blair Revolution Revisited(Mandelson,

2002).2 This is a central theme of the « Blair-Schröder platform » for the European elections of 1999. In this joint policy document which bears the hallmark of Peter Mandelson, labour market flexibility is presented as the way forward from "old" Euopean rigidities. The German social democrats were to be thereafter less enthusiastic in their endorsement of Blairism after disastrous results in these elections.

The only Scottish author of note to take sides with Conservative unionism was Alan Massie, although some

This campaign was to provide a platform for Tommy Sheridan, leader of Scottish Militant Labour ,and later of the Scottish Socialist Party, who was to be a major figure in parliamentary debates during the first two terms of the new Scottish parliamenet after 1999.

74,3% of voters expressed their support for a Scottish parliament in the referendum of the 11th of September 1997 (and

63,5% were in favour of tax-raising powers for the new parliament) whereas a week later in Wales only 50.1% voted in favour of the proposed assembly.


J Allard

S Cotin

F Faure

P.-J Bensoussan

F Poyer

C Duriez

H Delingette

L Grisoni

SOFA -an Open Source Framework for Medical Simulation

SOFA is a new open source framework primarily targeted at medical simulation research. Based on an advanced software architecture, it allows to (1) create complex and evolving simulations by combining new algorithms with algorithms already included in SOFA; (2) modify most parameters of the simulation -deformable behavior, surface representation, solver, constraints, collision algorithm, etc. -by simply editing an XML file; (3) build complex models from simpler ones using a scene-graph description; (4) efficiently simulate the dynamics of interacting objects using abstract equation solvers; and (5) reuse and easily compare a variety of available methods. In this paper we highlight the key concepts of the SOFA architecture and illustrate its potential through a series of examples.

Introduction

Computer-based training systems offer an elegant solution to the current need for better training in Medicine, since realistic and configurable training environments can be created. This can bridge the gap between basic training and performing the actual intervention on patients, without any restriction for repetitive training. However, in spite of the impressive developments in the field of medical simulation, some fundamental problems still hinder the acceptance of this valuable technology in daily clinical practice. In particular, the multi-disciplinary aspect of medical simulation requires the integration, within a single environment, of leading-edge solutions in areas as diverse as visualization, biomechanical modeling, haptics or contact modeling. This diversity of problems makes it challenging for researchers to make progress in specific areas, and leads rather often to duplication of efforts.

Objectives

For the past few years, there have been a few attempts at designing software toolkits for medical simulation. Examples include SPRING [START_REF] Montgomery | Spring: A general framework for collaborative, real-time surgical simulation[END_REF], GiPSi [START_REF] Goktekin | Gipsi: An open source software development framework for surgical simulation[END_REF], VRASS [START_REF] Kawasaki | VRASS (Virtual Reality Aided Simulation)[END_REF], or SSTML [START_REF] Bacon | The Surgical Simulation and Training Markup Language: An XML-Based Language for Medical Simulation[END_REF]. These different solutions aim at the same goal: providing an open source answer to the various challenges of medical simulation research and development. Although our aim is identical, we propose a different approach, through a very modular and flexible software framework called SOFA. This open source framework allows independently developed algorithms to interact together within a common simulation while minimizing the development time required for integration.

The main objectives of the SOFA framework are:

• Provide a common software framework for the medical simulation community Our main overall goal is to develop a flexible framework while minimizing the impact of this flexibility on the computation overhead. To achieve these objectives, we have developed a new architecture that implements a series of concepts described below.

The SOFA architecture

The SOFA architecture relies on several innovative concepts, in particular the notion of multi-model representation. In SOFA, most simulation components -deformable models, collision models, instruments, etc -can have several representations, connected together through a mechanism called mapping. Each representation can then be optimized for a particular task -e.g. collision detection, visualization -while at the same time improving interoperability by creating a clear separation between the functional aspects of the simulation components. As a consequence, it is possible to have models of very different nature interact together, for instance rigid bodies, deformable objects, and fluids. At a finer level of granularity, we also propose a decomposition of physical modelsi.e. any model that behaves according to the laws of physics -into a set of basic components. This decomposition leads for instance to a representation of mechanical models as a set of degrees of freedom and force fields acting on these degrees of freedom. Another key aspect of SOFA is the use of a scene-graph to organize and process the elements of a simulation while clearly separating the computation tasks from their possibly parallel scheduling. These concepts not only characterize SOFA but also provide a mean to address the goals described in section 1.1.

High-Level Modularity

Any simulation involves, to some extent, the computation of visual feedback, haptic feedback, and interactions between medical devices and anatomical structures. This typically translates into a simulation loop where, at each time step, collisions between objects are detected, deformation and collision response are computed, and the resulting state can be visually and haptically rendered. To perform each of these actions, the various algorithms involved in the simulation rely implicitly on different data structures for the simulated objects. In SOFA we explicitly decompose an object into various representations, in such a way that each representation is more suited toward a particular task -rendering, deformation, or collision detection. Then, these representations are linked together so they can be coherently updated. We call the link between these representations a mapping. Various mapping functions can be defined, and each mapping will associate a set of primitives of a representation to a set of primitives in the other representation (see Figure 1). For instance, a mapping can connect degrees of freedom in a Behavior Model to vertices in a Visual Model.

Fine Grain Modularity

One of the most challenging aspect of medical simulation is the computation, in realtime, of accurate biomechanical models of soft-tissues. Such models being computationally expensive, many strategies have been used to improve computation times or to reduce the complexity of the original model: linear elastic models have often been used instead of more complex non-linear representations, mass-spring methods as an alternative to finite element methods, etc. Each of these simplifications induces drawbacks, yet the importance of these drawbacks depends largely on the context in which they are applied. It becomes then very difficult to choose which particular method is most likely to provide the best results for a given simulation.

To address this issue in SOFA we have introduced, for the Behavior Model, a finer level of granularity than what is described in section 2.1. This permits for instance to switch from one solver to another in order to see the change in performance or robustness of the simulation, or to test different constitutive models. These changes can be done in a matter of seconds, without having to recompile any of the code, by simply editing an XML file. To achieve this level of flexibility, we have defined a series of generic primitives, or components, that are common to most physics-based simulations: DoF, Mass, Force Field, and Solver.

The DoF component describes the degrees of freedom, and their derivatives, of the object. This includes positions, velocities, accelerations, as well as other auxiliary vectors. The Mass component represents the mass of the object. Depending on the model, the mass can be represented by a single value -all the DoFs have the same mass, a vector -the DoFs have a different mass, or even a matrix as used in complex finite element models. The Force Field describes both internal forces associated with the constitutive equations of the model, and external forces that can be applied to this object. A variety of forces are currently derived from the abstract Force Field representation, including springs, linear and co-rotationnal FEM [START_REF] Muller | Interactive virtual materials[END_REF][START_REF] Nesme | Efficient, physically plausible finite elements[END_REF], Mass-Tensor, and Smoothed Particle Hydrodynamics (SPH). The Solver component handles the time step integration, i.e. advancing the state of the system from time t to time t + ∆t. To this end, the solver sends requests to the other components to execute operations such as summation of forces, computation of accelerations, and vector operations on the DoFs such as x = x + v • ∆t. Currently SOFA integrates explicit Euler and Runge-Kutta 4 solvers, as well as implicit conjugate-gradient based Euler solver [START_REF] Baraff | Large steps in cloth simulation[END_REF].

Scene Graph Representation

Building and maintaining the relations between all the elements of a simulation can become quite complex. Reusing concepts from the graphics community, we decided for a homogeneous scene-graph representation, where each component is attached to a node of a tree structure. While components are user-defined and can be extended at will, internal nodes are all the same. They only store pointers to their local components, as well as their parent and children nodes. This simple structure enables to easily visit all or a subset of the components in a scene, and dependencies between components are handled by retrieving sibling components attached to the same node. For instance, a Force Field component can access the DoF component by getting its pointer from the node. The scene-graph can also be dynamically reorganized, allowing for instance the creation of groups of interacting objects. Such groups can then be processed as a unique system of equations by the solver, thus permitting to efficiently handle stiff contact forces. Another advantage of using a scene-graph is that most computations performed in the simulation loop can be expressed as a traversal of the scene-graph. This traversal is called an action in SOFA. For instance, at each time step, the simulation state is updated by sending an Animate action to all Solver components. Each Solver then forwards requests to the appropriate components by recursively sending actions within its sub-tree. To illustrate the modularity in SOFA and the use of a scene-graph, we consider the example illustrated in Figure 2. In this example, two simulated objects -a rigid square and a simple Mass-Spring model -move through space and eventually collide. To compute the motion and deformation of the objects, we need to define for each of them a set of DoFs and a set of internal and external forces. The DoF component of the massspring model corresponds to the mass-points, while for the rigid object it corresponds to the position and orientation of the center of mass. This implies different data types for the DoFs of each object -a set of 3D vectors for the mass-spring and a 3D vector with a quaternion for the rigid object. Contacts between objects are possible through Collision Models associated with each object. The Collision Model for the mass-spring object consists of a set of vertices coincident with the DoFs of the object. The Collision Model for the rigid object -the square shape in Figure 2 -is rigidly attached to the body reference frame through a Mapping. The Mapping component is responsible for propagating the motion of the rigid body to the vertices of the Collision Model, and when collision occurs, the contact forces applied to the Collision Model are propagated back to the DoFs of the rigid body object. Since the vertices of the Collision Model do not coincide with the DoFs of the rigid object, we attach them to a different node of the scene-graph. However, as their motion is totally defined by the rigid body, they are not independent so this new node is created as a child of the rigid body node. The interaction force acts on the collision model vertices, independently of whether they are actual or mapped DoFs. At this point, actions can be propagated through the scene-graph to simulate both objects as a combined mechanical system.

Results

We present here several examples of simulations developed using SOFA. These examples illustrate the diversity and flexibility of the SOFA framework, in particular the ability to have objects with different behavior interact together. We also demonstrate some early results on the validation of algorithms used for simulating deformable structures.

Laparoscopic Simulation: the primary target for SOFA being Medical Simulation, we have developed an early prototype of a laparoscopic simulation system in which the liver and intestines are modeled as deformable models which can be manipulated using a laparoscopic instrument and can collide with the ribs, as illustrated in Figure 3. The modularity of the SOFA architecture allows us to easily experiment different constitutive models for the organs. In this example the liver is modeled as a co-rotational FEM and the intestines as a spring-based FFD grid. The separation between Visual, Collision, and Behavior models allows us to generate visually appealing simulations at interactive rates. Quantitative validation and comparison of algorithms: comparing algorithms for soft-tissue deformation only makes sense if they are compared against reference models issued from the real world. To this end, we have built a cylinder using silicon gel of known material properties, and then applied controlled constraints to this object as it was being CT scanned. The resulting surface obtained after image processing is illustrated in Figure 4. This surface was used as a Visual Model to which various Behavior Models were assigned -mass-spring, co-rotational FEM, and linear FEM. It then becomes very easy to visually and quantitatively assess the accuracy of the various models.

Chain Links: handling interactions between heterogenous models is prone to stability issues. To test the robustness of different algorithms we experimented with falling chains where each link uses a different Behavior Model, as illustrated in Figure 5. No constraints between links were pre-defined, instead we relied on collision detection and stiff contact forces to handle the contacts. Using implicit integrator handling dynamically-created groups of interacting objects resulted in a stable simulation.

Conclusion and Future Work

The SOFA framework currently integrates, in the same environment, a variety of different algorithms, from springs and co-rotational FEM models to FFD deformation grids, as well as implicit and explicit solvers, and several collision detection methods, such as continuous or proximity-based algorithms. Our framework also supports hard constraints and stiff interaction forces, using implicit or multi-step explicit integrators that handle dynamically-created groups of interacting objects. Our future work includes the support for multi-processing, topological changes, and haptic feedback. The SOFA web site, www.sofa-framework.org, can be visited for more information on our most recent results.

Figure 1 .

 1 Figure 1. Illustration of the multi-model representation in SOFA. Left: possible representations for a simulated object, with the Behavior Model controlling the update of the other representations through a series of mappings. Right: examples of these representations for a liver model. Notice how the Visual Model is more detailed than the Behavior Model and how the Collision Model relies on a very different representation.

Figure 2 .

 2 Figure 2. Left: two interacting bodies. The DoFs are shown as circles, and the forces as lines. A solid line describes an internal force, a dotted line an external force. Right: graph associated to the scene on the left. The nodes of the scene-graph, shown as stars, allow to model structured groups of components.

Figure 3 .

 3 Figure 3. Simulation of laparoscopic surgery using SOFA at interactive rates (about 50Hz).

Figure 4 .Figure 5 .

 45 Figure 4. Left: surface of an actual soft cylindrical object compared to a mass-spring, co-rotational FEM, and linear FEM models, under the same constraints. Right: a fluid modeled in SOFA using a SPH method.

  • Enable component sharing / exchange and reduce development time • Promote collaboration among research groups • Enable validation and comparison of new algorithms • Help standardize the description of anatomical and biomechanical datasets

Acknowledgments

We want to thank Sylvere Fonteneau, Damien Marchal, Xunlei Wu, Paul Neumann, Jeremie Dequidt, and Julien Lenoir for their contribution to the development of SOFA.


Dr David Seawright

The Conservative Party's Devolution Dilemma

Keywords: Devolution Conservative party, 'Scottish card', West Lothian, English laws

In the year of the tercentenary of the union between England and Scotland, the claim is made by the Conservative party that only it 'can make devolution work'. However, this article examines such a claim and also the prospects that a policy of 'English votes for English laws' will merely add to the dilemma facing the Conservative party; namely, that a party of 'positive unionism' cannot be a party of legislative devolution. The concomitant constitutional anomalies associated with devolution policy have merely been displaced rather than removed but the Conservative party has not yet developed credible polices that will address what has now become known as the 'English Question'.

Résumé

En cette année du tricentenaire de l'union entre l'Angleterre et l'Ecosse, le parti conservateur prétend être le seul parti « capable de faire fonctionner la dévolution ». Toutefois, cet article a pour objet d'étudier cette affirmation ainsi que l'hypothèse selon laquelle une politique de « votes anglais pour des lois anglaises » ne fera qu'accentuer le dilemme auquel est confronté le parti conservateur, à savoir qu'un parti d' « unionisme positif » ne peut être un parti de dévolution législative. Les anomalies constitutionnelles qui en résultent, associées à la politique de dévolution, ont été simplement déplacées mais n'ont pas disparu. En revanche, le parti conservateur n'a pas encore mis au point de politique crédible pour aborder ce que l'on appelle désormais la « question anglaise ».

Introduction

In the very year that sees the three hundredth anniversary of the signing of the Act of Union between Scotland and England in 1707 the Conservative and Unionist Party, a party that parades itself as the party of the union, faces a considerable dilemma regarding the formulation of policy that will underpin the future of that union. An increasing body of evidence points to an inexorable road towards separation; not least of which was the victory for the Scottish National Party at the 2007 Scottish Parliamentary election. And in an ICM opinion poll in November 2006, 52 per cent of Scots favoured independence while 31 per cent were against but more importantly the poll also found that 59 per cent of English respondents believed « it was time to let Scotland go it alone » with just 25 per cent disagreeing (Sunday Telegraph, 26 November 2006). The rise in the level of resentment found south of the border concerning a putative favourable position of Scotland and Wales vis-à-vis England, post devolution of 1999, has thrown into sharp relief the dilemma that faces the Conservative Party over its policy on devolution. As we shall see, throughout the 1980s and for most of the 1990s the party was virtually alone in its position of defending the constitutional status quo while warning against the anomalies that devolution entailed being a slippery slope to dissolving the union. However, in the wake of the New Labour victory of 1997 and the setting up of the Scottish Parliament and Welsh Assembly there was a volte-face on such policy; the Conservative Party now wholeheartedly supported devolution while espousing the mantra that only they « could make devolution work ». What was meant by this was that the Conservative Party would address the major anomaly of the West Lothian Question, which was now increasingly referred to as the « English Question », and which, in conjunction with the Barnett formula, were the main grievances of those English respondents mentioned above. In the same ICM opinion poll 62 per cent of English respondents thought that Scots MPs should not be able to vote on English laws while 60 per cent thought it unjustified that spending per head was higher in Scotland than in England (ibid). But, we will see below that such a mantra as « making devolution work » bore more the hallmark of an oxymoron than the intended effective electioneering slogan it was meant to be, particularly for Scotland and Wales. In short, in developing the «English votes for English laws» policy which was meant to address the anomalous position whereby Scots MPs (and to a lesser extent Welsh MPs) could be the arbiters of legislation for English constituencies while not having the ability to pronounce on such policy for their own constituents merely highlighted the constitutional imbroglio that asymmetrical devolution had now become and which further endangered the very union that the party wished to protect. Very soon after becoming leader David Cameron tasked Ken Clarke with setting up a Democracy Task Force to address such problems arising from Tony Blair's constitutional changes but one year later and the problem of the « English Question » was conspicuous by its absence in its first report (Conservative Party, 2007). Indeed, in the summer of 2006 a Scottish newspaper claimed that David Cameron, fearing that the argument over the constitution could get out of hand, « has ordered his troops to stop talking about it » (The Herald, 12 July 2006). But, with the increasing level of resentment found in England that will be no easy task and it is not only asymmetrical governance which is an issue for Conservative concern; for some time now the Party has had to face the reality of asymmetrical support, as outlined in table 1.1. and neatly encapsulates for us the reality that the party is now more the party of England than of Britain. Indeed, the fact that it won a greater share of the popular vote in England than Labour did in 2005 ironically added to this image problem and exacerbated its devolution dilemma. The party had never had a tradition of winning in Wales and its share of the vote there varies from a third to a fifth over the period but in Scotland the trend is one of precipitous decline with its marginality very clear from 1997 onwards. But, this was not always the case as in the 1950s and early 1960s the conventional approach was to refer to British homogeneity in voting behaviour (Budge and Urwin 1966). And, in the following section we note that the Conservative Party in Scotland (or more accurately the Scottish Unionist Party between 1912 and1965) was adept at playing « the Scottish Card » in its « successful » post war period but such a strategy had concomitant political dangers and would eventually rebound on a party that looked increasingly English. With this in mind we then explore the problem of a party being on the wrong side of a valence issue that devolution had now become. This then leads us to an examination of the contemporary issue of the «English Question» for the Conservative Party before concluding with a view on the future prospects for party policy on devolution. After all, Disraeli was fond of the refrain that the « Tory party, unless it is a national party is nothing » (Kebbel 1882 : 524) but the party's claim for One Nation (see Seawright, forthcoming) begs the question, which nation? The emphasis here is on England's relationship with Scotland rather than with Wales but this is hardly surprising with Scotland being the principal partner in that Act of Union and with Scotland having the longer history of administrative devolution and the greater legislative powers for its Scottish Parliament.

1. Playing the Scottish Card and its Boomerang Effect.

As early as 1885 a Tory Government led by Lord Salisbury had set up a Scottish Office (it was 1964 before we had the formation of the Welsh Office) and it also reconstituted the office of Secretary of State for Scotland which was abolished in 1746. In 1939 the Scottish Office was relocated to Edinburgh and it was to be Conservative governments that would increasingly strengthen the structures of administrative devolution.

Although the party had no truck with legislative devolution in this period, to reiterate, there is an argument that suggests that the party was adept at playing « the Scottish Card »; the idea that in practice it had done more than any other party to advance Scottish self-government in the post war years [START_REF] Miller | The End of British Politics? Scots and English Political Behaviour in the Seventies[END_REF]. The party's policy and proposals for near on twenty years did not deviate much from those outlined in a 1949 document entitled, « Scottish control of Scottish affairs ». This statement of policy, inter alia, proposed a Minister of State for Scotland with Cabinet rank to be appointed, along with a third Under-Secretary for Scotland, which would better distribute departmental duties, along with a proposed Royal Commission to examine Scottish affairs.

But, the Royal Commission on Scottish Affairs (The Balfour Commission) which was appointed in July 1952 and reported back in 1954 was precluded by its terms of reference from considering Parliamentary separation.

It was these immediate post war years which saw an attack on the Attlee Government's socialism which was equated with centralisation and London rule. These are the years which provide the material to underpin the « Scottish card » thesis. Undoubtedly much material and rhetoric abound which support Miller's view that proposing decentralisation, in the form of devolution policy, would endear a party to the Scots (although see [START_REF] Seawright | An Important Matter of Principle: the Decline of the Scottish Conservative and Unionist Party[END_REF], for a less simplistic approach). Churchill's famous 1950 General Election speech at the Usher Hall in Edinburgh, implicitly, if not explicitly, accepted the idea of Scottish home rule if the centralising menace of socialism could not be thwarted.

The principle of centralisation of government in Whitehall and Westminster is emphasised in a manner not hitherto experienced or contemplated in the (1707) Act of Union ... I frankly admit that it raises new issues between our two nations ... I would never adopt the view that Scotland should be forced into the serfdom of socialism as a result of a vote in the House of Commons (Miller 1981 : 21).

It is remarkable how similar the argument used by Churchill to question how far the concept of parliamentary sovereignty at Westminster should extend north of the border, in the face of Scottish public opinion, mirrors that used by the opponents of the Scottish Conservative Party in the 1980s and 1990s. But, at one time the fears of a one party hegemony in Scotland were the inverse of those found in the 1980s. In short, one criticism which until lately was levelled against the proposal for a Scottish Parliament is that it would be dominated by the Labour Party. But paradoxically, Glasgow University's study of the 1950 election which reported on the topicality of home rule at Glasgow election meetings found that it was: « though often coupled with an expressed fear that a devolved Scotland would be permanently Conservative » (ibid. : 25). Typical election addresses of this time also evince an attitude similar to Churchill's; an example is Mr T.G.D. Galbraith's who was the Scottish Unionist candidate in the 1948 Hillhead by-election and was to become an under Secretary of State for Scotland in 1959, and who declared under the heading, « Scotland »:

As one industry after another is nationalised we are finding that Scottish affairs are dominated by the control of Ministers and officials in England who are often ignorant of the ways of our Country. Socialist MPs may say that they are good Scotsmen but their whole policy is one of centralisation and control by Whitehall. I will resist this and demand that in each industry which has been nationalised a Scottish Committee shall be set up with full executive powers to deal with Scottish problems (General Election Addresses, Acc/10424, National Library of Scotland).

Moreover, Walter Elliot, the Scottish Secretary of State in the 1930s and a master at beating the Scottish drum when needed, would explicitly equate the socialist policy of nationalisation with the « denationalisation » of Scotland. For Elliot the consequence of such a centralising policy was London control at the expense of Scottish control. In a 1950 debate with the Labour Secretary of State for Scotland, Sir Arthur Woodburn, he took great pleasure in mischievously castigating Woodburn for having to ring up London for permission to use extra heating from an electric fire. He also criticised Labour in the same debate for having three English born MPs standing for election in Scotland (Miller 1981 : 22 & 25). Stoking the fires of this quasi-nationalism would eventually rebound on the party but as we see from between 1960between and 1966between and exploded in 1967between and 1968between (Miller 1981 : 24) : 24). This « explosion » led to Edward Heath adopting a policy for a form of moderate legislative devolution in 1968 that would set up an Assembly which would scrutinise legislation for Scotland. He, like many members of the party north of the border, was concerned about the perceived rise of nationalism. This was the era of the Thistle Group in the party and the group was formed in November 1967 after the Scottish Nationalist Party's success at the Hamilton by-election. Ironically, its founders and leading members were to later become some of the most prominent and committed unionists of the « Thatcher party »: Malcolm Rifkind, Michael Ancram, Lord Fraser of Carmyllie and Alexander Pollock. However, the Thistle Group at the time, in contrast to Heath's moderate proposal, envisaged a Scottish Parliament which would raise its own taxes. And in light of such sentiment in the Scottish party, Mr Heath took the opportunity to reverse party policy at the 1968 Perth Conference. The « Declaration of Perth » may be criticised for being merely grandiloquent posturing, but nevertheless, it was reported at the time as a watershed in Conservative thought on the governance of Scotland.

Even so, he (Heath) took Tory policy some considerable distance along a new avenue. He rejected separatism; he rejected federalism (which had some sympathy in the party); and, significantly, he rejected the status quo. In its place he virtually committed a future Conservative Government to set up an elected Scottish Assembly, to sit in Scotland (Glasgow Herald, 20 May 1968).

Although the proposals look pale by the standards of the 1990s, they represented a firmer commitment to change than anything offered by Labour at the time, led as it was in Scotland by the firmly anti-devolutionist, Willie Ross. The proposals were incorporated into the 1970 Manifesto, a three to one majority at the Scottish Conference of that year found in favour of them, and they were even acceptable to arch-Unionists such as Teddy Taylor (Bogdanor 1980 : 85). However, [START_REF] Marr | The Battle For Scotland[END_REF] emphasises the growing but latent opposition to Heath's proposals within the Scottish party and the Heath administration of 1970-74 has been much criticised for reneging on the commitment to set up a Scottish Assembly. However, extraneous events intervened which led to the failure to implement the policies promised at Perth. The Government believed it necessary to wait on the Kilbrandon Report (Report of the Royal Commission on the Constitution, 1969-73 set up by Harold Wilson in 1969) expected within a year of the 1970 election because quite simply the Commission threatened to resign if Heath proceeded with legislation on devolution which would have caused the government considerable embarrassment (Bogdanor 1980 : 85).

However, the present shadow defence secretary, Dr. Liam Fox, as a young Conservative around the time of his candidature for the Roxburgh and Berwickshire constituency, argued that the upsurge in nationalism was merely encouraged by the extant level of administrative devolution and that such nationalism received a major fillip from the proposal to create a devolved Scottish Assembly (Fox, et al 1988 : 6 & 7). While arguing that the clearest possible repudiation of legislative devolution was essential, these authors even questioned the existing arrangements of administrative devolution and stated that:

The Party of « positive Unionism » cannot also be the party of legislative devolution. The principles which would be embodied in the former are simply incompatible with the principles on which a system of legislative devolution would be established (ibid. : 11).

In the next section we see that both Margaret Thatcher and John Major had similar views on such incompatibility of the Union with a system of legislative devolution and it was now the Labour Party's turn to exploit « the Scottish card »; although the elections in May 2007 found them on the receiving end of their own « boomerang effect ».

2. « Wake up, wake up » to the Valence Problem.

By 1975, the Tories were in opposition under the new leadership of Mrs Thatcher. Mrs Thatcher spoke on behalf of a motion calling for a directly elected Assembly at the Scottish conference in 1976, which was passed by a substantial majority (Campaign Guide 1977). But by the end of that year her Shadow Secretary of State, Sir Alick Buchanan-Smith, had resigned from the front bench team in protest at the party's policy of opposing the Scotland and Wales Act. The policy was to deprecate Labour's Act as defective while not ruling out the principle of devolution, although Buchanan-Smith believed that ruling out devolution was exactly the attitude being conveyed to the Scottish electorate. Conservative literature of the period stressed that the Act would not remedy the genuine problems of Scotland and would only sow the seeds of discord and friction leading to the break up of the United Kingdom. Indeed, the pamphlet Scotland»s Government Today (1978) emphasised the dilemma of the «West Lothian Question», namely the role of Scots MPs after devolution, and was very prescient in alluding to the resentment that would be felt in England as a consequence of such a policy: After devolution Scots MPs will be able to vote on English housing, education and health but not on Scots housing, education and health. If the English are forced to accept policies they don't want, conflict will arise. The leading proponents of the « new right » agenda in the party in this period, such as Nigel Lawson, firmly believed that laissez-faire economic policy in tandem with getting government off the peoples» backs was truly devolutionary as it would empower the people directly (Bogdanor 1979 : 112;Marr 1995 : 155). Of course, Thatcher eventually took this course and the party in Scotland loyally followed this unionist approach and her successor John Major, if anything, hardened the stance. So the Scottish Conservatives entered the 1992 election battle, deprecating the independence and devolutionary positions taken by the other parties while emphasising that it was the only true unionist party. Ian Lang, the Secretary of State for Scotland, urged the parliamentary candidates to champion the union (The Times 23 March 1992) and John Major informed his biggest election rally at Wembley in April:

If I could summon up all the authority of this office I would put it into this single warning -the United Kingdom is in danger. Wake up. Wake up now before it's too late (The Scotsman, 6 April 1992).

With the party in Scotland in 1992 polling nearly half the level of the vote it had in England the problems for it were obvious after this election and the other parties and the Scottish media were not slow in exploiting this weakness [START_REF] Seawright | An Important Matter of Principle: the Decline of the Scottish Conservative and Unionist Party[END_REF]). Ironically, with Gordon Brown's imminent elevation to the post of Prime Minister in mind, he was questioning the right of any English MP to legislate for Scotland as early as 1983.

In February 1983, Gordon Brown, as vice-chairman of the Scottish Labour party, questioned whether Conservative rule of Scotland would be legitimate if Labour won in Scotland again. The job of the Scottish Secretary of State should be made « untenable », Brown argued (Mitchell 2006 : 467). These problems for the party were clearly illustrated in the 1997 election and in the September 1997 Referendum Campaign. The « Think Twice » campaign group which was against the setting up of the parliament was represented in the press as a marginal group of die hard Tories and Donald Findlay QC the eloquent spokesman for the « No-No » campaign delineated their problems in a humorous diary published in the Scotland on Sunday newspaper (14 September 1997). Findlay freely admitted to it being an uphill struggle.

The three other parties were against him but the bias of the media and the intolerance he encountered made the task an impossible one (ibid.). More importantly, some of the old anti-devolutionists from the left, like Tam Dalyell of « West Lothian » fame, were still around but he appeared isolated unlike in 1979 when Labour members such as Robin Cook agreed with him that it was not the Devolution Bill that should be killed but the issue itself. Indeed, A month before the 1997 Referendum, Liam Fox -promoted to the post of « constitutional spokesman » in June 1998 -announced that the Conservatives would try to exclude Orkney and Shetland from the remit of the Scottish Parliament, if the referendum proved they were hostile to home rule (The Scotsman, 7 August 1997). It transpired that the vote in favour of devolution rose by around a third in both the islands from that recorded in 1979. The party's opponents ridiculed Fox's suggestion as indicative of how far removed from reality the Tories in Scotland had become. This anti-Conservative style and tone from the main Scottish national newspapers merely confirmed the sea change of opinion that had taken place in Scotland from around the mid-1970s or even earlier [START_REF] Seawright | An Important Matter of Principle: the Decline of the Scottish Conservative and Unionist Party[END_REF]. The Unionist ethos was no longer rooted in Scottish consciousness, the Conservative Party in Scotland would now be the party perceived as having an « alien » identity; an « anglicised » one. However, it may be far more useful to view such an issue as devolution for Scotland not in terms of a traditionally « position issue », where the parties take up a distinct political position towards the issue, like most issues of a left-right nature. It may well be that sometime in the 1980s, reinforced in the 1990s, and due in no small measure to Labour exploiting the « Scottish card » in opposition to Thatcherism that it underwent a metamorphosis into one of a valence framework [START_REF] Stokes | Valence Politics[END_REF]; as this would fit comfortably with the idea of an increasingly vivid portrayal of the Scottish Tories -by a left wing Scottish party consensus and a left wing « Scottish establishment » -as being alien to the Scottish body politic.

Stokes differentiates position issues that are on our left-right ordered dimension from valence issues that are more to do with the degree to which parties are linked in the public's mind with conditions or goals or symbols of which almost everyone approves or disapproves (1992 : 143). Adapting Stokes work for Scottish politics has us, in this case, viewing devolution for Scotland itself as the valence issue. Thus, such a valence issue acquires its power from the fact that rival parties are linked with the universally approved symbol of Scottishness and the universally disapproved symbol of non-Scottishness. The valence framework also facilitates the venal exploitation of negative campaigning. A valence issue will deliver maximum support for a party if its symbolic content is of high importance to the electorate and there is complete identification of the party with the positive symbol and of the rival party with the negative symbol . Throughout the last two decades of the twentieth century the left wing parties, Labour, the Liberal Democrats in all their guises and the SNP, successfully portrayed the Tories in Scotland with the negative universally disapproved symbol of « un-Scottish » [START_REF] Seawright | The Scottish Conservative and Unionist Party: the lesser spotted Tory[END_REF]. One has only to review the Scottish Press, at the time of William Hague's speech on the need for a solution to the West Lothian Question, for a good example of the use of this negative symbolism. The argument for English MPs having similar rights to Scottish MSPs was viewed by the other three main Scottish parties as inherently divisive, typical of Tory anti-Scottishness and « the small minded attempt to seek revenge on the voters who rejected them » (The Scotsman, 14 November 2000). But, this issue of the « English Question » will not easily go away and for Conservatives it has to be addressed in search of a solution to the major anomalies inherent in devolution itself. For them, to ignore the need for this « search » is to accept the inevitable break up of the Union.

The English Question?

In his excellent article on the « unfinished business » of devolution Mitchell examines questions of legitimacy surrounding this issue and takes us through the « decline of legitimacy pre-devolution » before analysing its « spillover » and the now « delegitimation » regarding England: « In essence, one of the predictable consequences of devolution has been to displace rather than remove the legitimacy deficit » (2006 : 466 & 468). This displacement may have been predictable for the Thatcher and Major administrations but New Labour chose to ignore it to the extent that Derry Irvine, Blair's first Lord Chancellor, declared: « the best way to deal with the West Lothian question was to stop asking it ». But as many commentators, on both sides of the border, have pointed out there is: « Fat chance of that, and not only because of Tam Dalyell. The average English voter is beginning to be able to find West Lothian on the political map » [START_REF] Anderson | Ungrateful Scots have finally awakened the dormant nationalism of the English[END_REF]). Indeed, this opportunistic avoidance of the question was compounded in the sense that this West Lothian mindset seemed to be acknowledged by the major parties in the pre-devolution era. With the existence of the Scottish Office in Edinburgh a convention developed that certain offices of state, notably those of Health and the Home Office, would not be filled by a Scot as such matters relating to Scotland were under the jurisdiction of the Scottish Office. No Scot had occupied such posts since the 1930s but this convention was broken first in 2003 with John Reid's appointment as Secretary of State for Health and then in 2006 when he was moved to the Home Office (Mitchell 2006 : 470). Interestingly, at the 1992 Election, Robin Cook, at the time Shadow Health Secretary, in an answer to a question about Scots Ministers of State legislating for England while not having a similar authority for Scotland replied:

Absolutely clear and simple answer to this -once we have a Scottish Parliament, handling Scottish health affairs in Scotland, it is not possible for me to continue as Minister of Health, administering health in England (Harper 1992 : 13).

Although the Conservatives were the most vociferous of the major parties on this English question many within the Labour party shared their concern. The Scottish Affairs committee, with a Labour majority, believed the West Lothian Question was « a time bomb that urgently needs to be defused » and stated that it was « a matter of concern to us that English discontent is becoming apparent » (Daily Telegraph, 20 July 2006). This discontent, again found within Labour party ranks south of the border also, was echoed in some of their views concerning the Barnett formula. Simon was quite explicit in blaming Gordon Brown as the cause of this frustration over Brown's sensitivity to any change to the Barnett formula but although the minutiae of the formula is rather more complex than is commonly thought (see [START_REF] Midwinter | The Changing Distribution of Territorial Public Expenditure in the UK[END_REF] there is no denying the political mileage that can be milked from such headlines as « Scots get £1,200 a head more per year » or « £11.3bn the extra amount that the Government spent in Scotland in addition to the money it raised there » (The Times, 12 December 2006). David

McLean the former Tory chief whip remonstrated that:

Not only have we got an unbalanced Parliament in Westminster, with Scottish MPs having more rights than English MPs, we are having legislation foisted on England with the votes of Scottish MPs. We are getting fundamentally greater expenditure on people in Scotland, which is aggravating rural poverty in England.

If the Government does not address this, it will find an unstoppable demand in England for separation (ibid).

Such attitudes led to the « English votes for English laws » policy included both in William Hague's and Michael Howard's manifestos for the 2001 and 2005 general elections respectively. The assumption of this policy was that the Speaker of the House of Commons could actually designate which Bills were solely for « English Laws » and thus enable the exclusion of any votes that were not from English constituencies. But in reality it would be very difficult to discern such a clear division to such legislation and for the Speaker to unequivocally declare when there would be no impact from such laws on the other nations of Great Britain. But as Vernon Bogdanor was to point out such an approach would still create anomalies as it was not that easy to determine which Bills would be precisely English, or English and Welsh, as finance for Scotland and Wales is through a block fund based on the Barnett formula «the size of which depends on expenditure in England »; thus if education spending was cut back in England this would have a knock on effect on Scotland (Financial Times, 10 February 2006). Bogdanor warned of the implications of such an approach for the Union as did Jack Straw, the Leader of the House of Commons, when he warned that « this approach would start to dissolve the glue which binds our Union, and over time would lead to the break-up of the United Kingdom itself » (Straw 2006 : 12). However, both Bodganor and Straw failed to acknowledge New Labour's part as a « catalytic agent » in the attenuation of that constitutional glue in the first place. Something not lost on John Major in 2007, when more than a decade after the 1992 Election where he had warned of devolution being the Trojan horse for separation, he stated:

If the Union is now unstable, Labour bears the greatest single responsibility. It scoffed at all warnings and -for partisan advantage -passed a wholly one-sided Devolution Act that gave Scotland all it hoped for with no regard to the effect across the United Kingdom. … And it would be foolish not to acknowledge that a Scottish prime minister with a Scottish constituency will highlight afresh the constitutional anomaly (Daily Telegraph, 9 March 2007).

Above we encountered Gordon Brown questioning the legitimacy of Conservative rule of Scotland if Labour won in Scotland again but now with so many Scots holding office in some of the most important UK Ministries, no less in the office of Prime Minister itself, the Conservatives are now beginning to question the legitimacy of Labour rule for England if the Conservatives win in England again. The job of Prime Minister could well be untenable. Of course, the constitutional Pandora's box has now been opened and the question to be asked is, is it possible for the Conservative party to « make devolution work » and to reverse that seemingly inexorable path towards separation?

4. In Conclusion: One Nation but which?

It is quite plain that both major parties have used the constitutional question as a political football each in turn exploiting « the Scottish card » but for John Major and many other Conservatives it has been with the foreseen consequences of merely aiding and abetting the Nationalists. Unfortunately, that call for « positive unionism », which would have addressed and challenged the dangers and anomalies in both administrative and legislative devolution, was by 1988 too late; when Fox and his colleagues sounded the alarm. Although, in fairness they did indeed identify the party's ongoing dilemma: « Yet for too long, on the central issue of devolution, it vacillated between two options: neither rejecting, nor embracing, either with any very significant degree of fervour, consistency or conviction » (Fox et al 1988 : 11). However, it is now inconceivable that the party could turn the clock back regarding the New Labour devolution reforms, although at the 2005 General Election there was ambiguity concerning Wales:

We remain strongly committed to making a success of devolution in Scotland, so that it delivers for the Scottish people. In Wales we will work with the Assembly and give the Welsh people a referendum on whether to keep the Assembly in its current form, increase its powers or abolish it (Conservative Party 2005 : 21).

But, Tam Dayell, the former member of the eponymous West Lothian seat and thus the source of the famous Question itself, now makes the point that: « It is the nature of parliaments that they claim more and more powers » and that he has no apparent pleasure in feeling increasingly justified for his prediction that devolution would be a motorway to independence and concedes that « independence may be better than a halfway house » (Scotland on Sunday, 8 October 2006). And Michael Fry, an erstwhile Conservative Unionist, has now had a very public conversion and is now for independence because of the completely hopeless state of devolution: « As I don't think we can go back, we have to go forward » (The Times, 14 January 2007). This then is the dilemma facing Cameron's Conservative party; how does it address these views in Scotland while cognisant of the increasing resentment felt in England over the New Labour's « one sided devolution reforms », while at the same time not « aiding and abetting » the views of English Nationalists? The party cannot just ignore the English Question, although some left wing commentators do indeed adopt the rather puerile Lord Irvine position of simply advocating the not asking of it (see Jonathan Freedland, The Guardian, 5

Table 1

 1

	.1.	The Conservative Share of the vote in England, Scotland and Wales, 1950-
	2005.
		1950	1951	1955	1959	1964	1966	1970	1974F 1974O
	England	44.0 49.2	50.6	50.2	44.1	42.8	48.4	38.9	40.2
	Scotland	46.2	49.6	50.1	47.6	40.6	37.6	38.5	24.7	32.9
	Wales	28.3 33.1	33.5	33.8	29.4	27.9	27.7	23.9	25.9
		1979	1983	1987	1987	1997	1999* 2001	2003* 2005
	England	47.2	46.0	46.2	45.5	33.7	n/a	35.2	n/a	35.7
	Scotland	31.4	28.4	24.0	25.7	17.56 15.6	16.6	16.6	15.8
	Wales	32.2	31.0	29.5	28.6	19.6	15.8	21.0	19.9	21.4

*These are the « devolved » elections for Scotland and Wales and figures represent the « first or constituency vote » of the Additional Member Electoral system for direct comparability with the Single Member Plurality System used for Westminster elections. Source:Westminster Elections: data from the Nuffield Studies, The British General Election of 19xx -2005. Scottish and Welsh Elections: data from Jones, R. W. and Scully, R. (2006). "Devolution and Electoral Politics in Scotland and Wales", Publius: The Journal of Federalism, 36 / 1.

Table 1 .

 1 1 delineates the Conservative share of the vote in England, Scotland and Wales between 1950 and 2005

  table 1.1., the 1950s were relatively successful years for the Scottish Unionist Party with the Conservatives holding power atWestminster from 1951 to 1964[START_REF] Miller | The End of British Politics? Scots and English Political Behaviour in the Seventies[END_REF] points out the 1950s were a quiescent period regarding home rule aspirations. It would appear that these Scottish Tory measures and the dismantling of Labour's centralising nationalisation were sufficient to meet Scottish aspirations at this time. In fact Miller provides a simple objective measure of the amount of public attention given to the issue in this period. He records the number of lines devoted to the heading « home rule » in the Glasgow Herald index published until 1968 and concludes that there was very little until 1946; then, in response to MacCormack's National Convention assemblies on home rule, a swift rise to a peak in 1950, followed by a sharp drop in 1951 and 1952 and a progressive decline until 1960. Interest revived slightly

  For example, Sion Simon the Birmingham Labour MP was of the opinion that Scotland should no longer benefit financially from a formula devised in 1976, particularly when they now had a Parliament. English MPs are angry about how much core government money their regions don't receive compared, in particular, with Scotland. « If my constituents knew », one disgruntled northerner told me, « how many more pounds per head they would be getting if the town were transplanted to Scotland, they»d go crazy ». … John Prescott gave voice to this disgruntlement in a surprising intervention a couple of weeks ago, when he admitted that the current formula cannot pertain indefinitely. For decades a champion of English regionalism, Mr Prescott's outburst was ascribed by one leading English minister as « pure frustration, I guess » (Daily Telegraph, 30 April 2001).

  The complexity of such territorial implications is evident in the parliamentary debates on the two « private member » Bills which were introduced firstly into the House of Lords by Lord Baker of Dorking in February 2006 and then into the House of Commons by Robert Walter, the Conservative MP for North Dorset, in March 2007. Speaking on his « House of Commons (Participation) Bill » Robert Walter declared:My Bill follows a similar Bill that was introduced in the House of Lords in the last Session by the noble Lord Baker which sought to do very much the same as what I propose. However, a number of anomalies were identified in his Bill. Therefore, the basic provisions of my Bill are that, in respect of primary legislation, the Speaker may designate whether it should be considered by « all members returned for constituencies in England and Wales » -thus taking account of the fact that Wales does not have primary legislative powers -« all members returned for constituencies in Scotland… all members returned for constituencies in Northern Ireland », or any combination of those (House of Commons Hansard Debates, 9 March 2007: Column 1790).


Arthur Lévy

Arnaud Poitou

Steven Le Corre

Eric Soccard

Ultrasonic Welding of Thermoplastic Composites, Modeling of the Process

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.

INTRODUCTION

This work aims at modeling an original welding process for composite material with thermoplastic matrix. Triangular bulges, called "energy directors" are molded with matrix only, on a width of two centimeters on the border of one of the plate to be welded. The two plates are then positioned in order to cover each other on the width of the energy directors. The process then consists in applying an ultrasonic (20 KHz) sinusoidal compression stress between the two plates as shown in figure 1. The strain concentrates at the interface, in the energy directors, that melt because of the viscous dissipation [START_REF] Grewell | Welding of plastics: Fundamentals and new developments[END_REF]. The triangles then progressively flow on the whole interface and perform welding of the two composite planes (see figure 2). Even if no fiber crosses the interface, the cover is wide enough to transmit the stress which allows the process to be used for large scale assemble. The main problem for modelling such a process comes from the existence of two time scales. Indeed, simulating each ultrasonic cycle would induce huge calculation times since the whole process is performed over thousands of cycles. Such a drawback can be overcome by the timehomogenization technique.

MODELING OF THE PROCESS

Mechanical problem

Let us consider a single energy director as described ABSTRACT: The process of ultrasonic welding is widely used in the industry. Nevertheless, its numerical modelling, essential for the aeronautic industry, is quite difficult because of the two time scales present in the process. After explaining principle of the welding, a method of time homogenization is presented in order to write down three different thermal and mechanical systems of equations. Since one of those problems implies moving free surface, a numerical tool using the level-set method was used to solve them. Key words: Polymer, Welding, Time-homogenization, Visco-elasticity, Numerical simulation, Level-set.

Ultrasonic Welding of Thermoplastic Composites, Modeling of the Process.

A. LEVY 1 , A POITOU 1 , S. LE CORRE 1 , E. SOCCARD 2 in figure 3. The mechanical problem is written down using a Maxwell visco-elastic law:

! ˙ " + " = 2#D (1)
where λ is the relaxation time, σ is the extra stress tensor, η the viscosity and D the strain rate tensor. The composites plates are supposed to be perfectly rigid compared to the energy director. The displacement of the tip of the director is then supposed to be zero, whereas the displacement of the upper part can be decomposed into a "microchronological" sinusoidal displacement α.cos(ωt) due to the short period of the ultrasound (around 50 micro-seconds), and a "macro-chronological" displacement ud due to the squeezing of the director during the process (around one second).

The whole mechanical problem can finally be written as follow:

div(! " pI ) = 0 # ! ! + ! = 2.$.D;!div(v) = 0 v = v d (t) + a sin(%t) (& sup ) v = 0 (& 0 ) (! " pI ).n = 0 (& lat ) ' ( ) ) ) * + , , , - , , , (2)
2.2 Homogenization.

First, dimensionless time scales t * and τ * are introduced such as t=λ 0 t * and τ * =ωt, where λ 0 =1s is the characteristic time of the process. t * being the large time variable and τ * the short time variable traducing the fast variations. Then, one can define the scale factor ξ :

! = t * " * = 1 #$ 0 % 10 &6 (4)
The two time sales are well separated. This will reasonably allow us to use a technique of homogenisation in time to model the process [START_REF] Guennouni | Sur une méthode de calcul de structures soumises à des chargements cycliques: l'homogénéisation en temps[END_REF].

To proceed, each variable Φ of the problem is written as a function of t * and τ * .The time derivative of Φ can  then  be written  as :

! ! = d! dt = 1 " 0 #! #t $ + 1 " 0 1 % #! #& $ (5)
Dimensionless equations corresponding to the system (2) can be deduces. The constitutive equation and the boundary condition on Γ sup become:

! " #$ " #t " + ! " 1 % #$ " #& " + $ " = 2.' " D " v " = v d " (t " ) + R% (1 sin(& " )!!!() sup ) * + , - , (6)
where all the stared quantities are dimensionless and quantity R is of order 0 in ξ.

Asymptotic expansion in time [START_REF] Boutin | Study of thermosensitive heterogeneous media via space-time homogenisation[END_REF] consists in writing each unknown as an expansion in power of ξ starting from power -1 because of the velocity condition [START_REF] Wang | FEM Investigation of the Temperature Field of Energy Director During Ultrasonic Welding of PEEK Composites[END_REF].

! " = ! #1 " $ #1 + ! 0 " + ! 1 " $ + ! 2 " $ 2 ... (7)
where each Φ i are periodic in τ.

Using identification of first orders of ξ and averaging over a period, we can extract from the original thermo-mechanical problem two coupled systems of equations.

The two mechanical problems to solve

The first system of equations is the microchronological mechanical problem, which is an hypo-elastic problem in the director. The velocity condition of which is sinusoidal and comes from the -1 order:

! " #$ 0 " #% " = 2& " D '1 " div " ($ 0 " ' p 0 " I ) = 0;!!div(v '1 " ) = 0 v '1 " = R.sin(% " ) (( sup ) v '1 " = 0 (( 0 ) ($ 0 " ' p 0 " I ).n = 0 (( lat ) ) * + + + + , - . . . . / . . . . (8)
The second is called macro-chronological problem.

It consists in a visco-elastic flow. Its solution will give the geometry changes needed for solving the other system of equations.

! " #<$ 0 " > #t " + < $ 0 " >= 2% " < D 0 " > div " (< $ 0 " > + < p 0 " > I ) = 0;!!div(< v &0 >) = 0 < v 0 " >= v d " (t " ) (' sup ) < v 0 " >= 0 (' 0 ) (< $ 0 " > + < p 0 " > I ).n = 0 (' lat ) ( ) * * * * + , - - - - . - - - - (9)
In this equations <.> denotes the time average over an ultrasonic period.

Thermal Analysis

For the sake of simplicity, thermal analysis was not accounted for. Nevertheless, one has to do it simultaneously since the material parameters at each point depend on the temperature field θ. Starting from the initial thermal problem where the dissipation energy is introduced as a source term:

!c( ! " + grad".v) = k#" + 1 2$ % : % k.grad(").n = 0 (& lat ) k.grad(").n = h.(" ' " inf ) (& 0 ( & sup ) ) * + , - .
/ .

(10) and applying the same analysis, we can extract the dominating first order system:

!" 1 # !t * + grad" 1 # .v = A.$ # " 1 # + B < % 0 # : % 0 # > grad # (" 1 # ).n = 0 (& lat ) grad # (" 1 # ).n = Q < " 0 # > (& 0 ' & sup ) ( ) * * + , - - . - - (11)
The source term turns out to be given by the microchronological problem only. Values of A, B and Q can be calculated from thermal parameters and be found of order 0 in ξ. For each time step the three systems of equation ( 9), ( 10) and ( 11) are solved successively. Since coupling between the three systems is rather weak, the three problems are solved iteratively until the residual of the three variational forms are simultaneously smaller than a prescribed tolerance.

NUMERICAL PROCEDURE

To solve each problem (which can be non-linear) a Newton-Raphson method was used. The global procedure is explicit in time, but the thermal problem is solved by an implicit backward euler formulation.

Interpolation

The elastic problem was solved in term of displacement, with a second order interpolation. A second order was also set for the temperature. The flow problem was solved by a mixed formulation in velocity and pressure, with a conventional P2/P1 approximation.

Management of the free surface

Since moving of free surface occurs in the macrochronological problem. A level-set method was used in an eulerian framework. This was performed using the C++ library X-Fem developed in the laboratory. The global evolution of the domain is then managed by the calculation of the level-set. It is updated at each time step using the solution of the macrochronological problem.

Meshing

The mesh is made of regular triangles over the whole domain, which is reduced to a half energy director, a part of the lower plate and the void between directors. It is shown in figure 5.

Material Data

The material parameter used in the simulation were adapted from values given by [START_REF] Nicodeau | Characteristics of resistance welding of lap shear coupons : Part I : Heat transfer[END_REF]5]. They are given in table 1.

For the elastic micro-chronological system, the material was assumed to be isotropic. In a first approximation the Young modulus was set as an affine function of temperature. The Poisson ratio was set to 0.49 in order to approach incompressibility of equation ( 9). Although the macro-chronological problem should be visco-elastic, it was reduced to a viscous problem. Indeed, the macroscopic time of the process is rather long compared to the characteristic Maxwell time of the visco-elastic law. A power law given by equation ( 13) was used to model the viscosity.

! = ! 0 .D eq n"1

(12)

where D eq is the equivalent strain rate and η 0 is the Newtonian viscosity which is temperature dependant. In a first approximation, it is set as an affine function of temperature. Further on, it may be implemented as an Arrhenius law. The conductivity and heat capacity were also supposed to be linear functions of the temperature.

FIRST RESULTS

Even though the convection of the temperature field will handled using operator splitting methods) and the propagation of the levelset is not implemented yet, first results can be presented. The three coupled systems of equation were resolved and gave similar results to the literature [START_REF] Wang | FEM Investigation of the Temperature Field of Energy Director During Ultrasonic Welding of PEEK Composites[END_REF]. Namely that the hotter zone is located near the tip of the energy director as shown in figure 6. This is in agreement with the source term repartition of figure 5. Moreover, the fast temperature rising at the tip of the director shows that it is efficient for concentrating energy.

CONCLUSIONS

A new method was developed to handle multiple time scales. The three resulting problems were solved using original numerical tools. First results are in agreement with literature and further development should allow geometry changes.

Taking into account finite deformations may be an improvement of our modelling.

Figure 1 :

 1 Figure 1 : Ultrasonic welding of two plates

Figure 2 :

 2 Figure 2 : Melting and flowing of an energy director.

Figure 3 :

 3 Figure 3 : Geometry of the initial energy director.

Figure 4 :

 4 Figure 4 : Solving scheme.

  Newtonian viscosity η 0 =4e7-3.5e5(T-T ref ) Pa/s Power index n=0.54 T h e r m a l Reference temperature T ref =50°C Capacity ρC=1.6e6+2200(T-T ref )W/K.m 3 Conductivity k=0.25 W/m 2 K

Figure 5 :

 5 Figure 5 : Source term calculated from the elastic problem for the first time step.

Figure 6 :

 6 Figure 6 : Temperature field calculated at time 2.3 ms which is equivalent to the 12 th time step.

GeM, Ecole Centrale Nantes, Université de Nantes -1 rue de la Noé 44321 Nantes, France. e-mail: [arthur.levy; steven.le-corre; arnaud.poitou]@ec-nantes.fr

EADS IW -Technocampus, 1 rue de la Noé 44321 Nantes, France. e-mail: eric.soccard@ eads.net;