Mario Le Glatin
email: mario.le_glatin@mines-paristech.fr

Pascal Le Masson

Benoît Weil

MEASURING THE GENERATIVE POWER OF AN ORGANISATIONAL ROUTINE WITH DESIGN THEORIES: THE CASE OF DESIGN THINKING IN A LARGE FIRM

Keywords: innovation, design thinking, aerospace, routines, change management

This article studies how a large firm uses Design Thinking (DT) as a core process in specific design and development team whose mission is to bridge the gap between unidentified market needs and business units research & development effort. We analyse two cases where new concepts were developed and promoted to business units for implementation by following DT methodology. Our study shows that the DT routine reveals some generative power to explore the user perspective, yet it appears uncontrolled when it comes to generate a wider variety of ideas and knowledge challenging the design ecosystem ontology omitted and made invariant through user-focus hence it faces difficulties to engage with stakeholders and other organisational routines for an enhanced creativity and organisational change.

INTRODUCTION

Design Thinking (DT) as a design toolbox has raised a lot of interest over the last twenty years among businesses looking for innovation systematisation beyond traditional decision-making and product development paradigm [START_REF] Liedtka | Perspective: Linking Design Thinking with Innovation Outcomes through Cognitive Bias Reduction[END_REF]. When it comes down to exploration and exploitation (March, 1991;[START_REF] O'reilly | Organizational Ambidexterity: Past, Present, and Future[END_REF], DT is appears as a ready-made creativity and strategic tool managers (Lee & Joo, 2015;[START_REF] Lockwood | Design Thinking in Business: An Interview with Gianfranco Zaccai[END_REF][START_REF] Rhinow | Design Thinking: Expectations from a Management Perspective[END_REF]. In less than twenty year, DT has left quite a large footprint in the industry, being extended from the works of David Kelley and Tim Brown at IDEO [START_REF] Brown | Design Thinking[END_REF], becoming a way of managing [START_REF] Martin | The Design of Business: Why Design Thinking Is the next Competitive Advantage[END_REF], and it is now being showcased in several large firms across the world.

A TOPIC OF INCREASING INTEREST WITH A GRADUAL DEFINITION CONSENSUS

As a consequence, an increasing amount of scholars try to understand its origin, scientific background and in-practice use [START_REF] Bauer | Design Thinking: Epistemic Plurality in Management and Organization[END_REF]Buchanan, 2008;[START_REF] Carlgren | Design Thinking in Innovation, in Practice: The Case of Kaiser Permanente[END_REF]Cooper & Junginger, 2009;Efeoglu et al., 2013;[START_REF] Kimbell | Rethinking Design Thinking: Part II[END_REF][START_REF] Kimbell | Rethinking Design Thinking: Part I[END_REF][START_REF] Carlgren | Exploring the Use of Design Thinking in Large Organizations: Towards a Research Agenda[END_REF]. DT has been introduced in the management field and in firms as change management means [START_REF] Brown | Change by Design[END_REF][START_REF] Brown | Change by Design[END_REF][START_REF] Brown | Design Thinking[END_REF]Dunne & Martin, 2006;[START_REF] Lockwood | Design Thinking in Business: An Interview with Gianfranco Zaccai[END_REF] whilst "democratising" design and fostering design as a practice with a set of decontextualized tools. Yet, it remains unclear to grasp the impact of DT, and what it fully becomes when turned into a firm practice practice [START_REF] Carlgren | Design Thinking in Innovation, in Practice: The Case of Kaiser Permanente[END_REF]Lee & Joo, 2015;[START_REF] Carlgren | Exploring the Use of Design Thinking in Large Organizations: Towards a Research Agenda[END_REF][START_REF] Seidel | Adopting Design Thinking in Novice Multidisciplinary Teams: The Application and Limits of Design Methods and Reflexive Practices[END_REF].

DESIGN THINKING SEEN AS A SET OF ROUTINES

Recent works have put forward a framework to identify DT as an organisational routine in its various forms [START_REF] Carlgren | Framing Design Thinking: The Concept in Idea and Enactment[END_REF]) which we will refer to. Moreover, as a design method, its performance, impact on the organisation, knowledge management, remain to be clarified and it is only very recently that its contribution in terms of cognitive bias reduction for decision-making process has been brought to the fore [START_REF] Liedtka | Perspective: Linking Design Thinking with Innovation Outcomes through Cognitive Bias Reduction[END_REF] among other 'soft facts' [START_REF] Schmiedgen | Measuring the Impact of Design Thinking[END_REF].

THE DYNAMICS OF ROUTINES: GENERATIVE POWER OF DESIGN THEORIES AND

METHODS

In the routine literature, several features and dynamics are discussed to explain macro organisational dynamics [START_REF] Zollo | Deliberate Learning and the Evolution of Dynamic Capabilities[END_REF], to highlight coordination mechanism [START_REF] Jarzabkowski | Toward a Theory of Coordinating: Creating Coordinating Mechanisms in Practice[END_REF][START_REF] Spee | The Influence of Routine Interdependence and Skillful Accomplishment on the Coordination of Standardizing and Customizing[END_REF] and reveal the generative power of routines, in conjunction with organisational exploration [START_REF] Cohendet | Always Playable: Recombining Routines for Creative Efficiency at Ubisoft Montreal's Video Game Studio[END_REF][START_REF] Deken | Generating Novelty through Interdependent Routines: A Process Model of Routine Work[END_REF][START_REF] Pentland | Dynamics of Organizational Routines: A Generative Model[END_REF]. This generativity usually refers to the performance of the routines being able to resource themselves, to recombine, select and evolve in novel routines, which refers to the phenomenon of having a routine being able to manage collective acceptance to build new rules. In a separate but close field, design theory literature has already elaborated along with contributions from cognitive psychology what generativity is, based on formal theory of design. This contributed to analyse generativity from a cognitive and a social perspective: knowledge expansion and conceptual exploration [START_REF] Agogué | Rethinking Ideation: A Cognitive Approach of Innovation Lock-Ins[END_REF][START_REF] Agogué | Orphan Innovation, or When Path-Creation Goes Stale: A Design Framework to Characterize Path-Dependence in Real Time[END_REF][START_REF] Hatchuel | Beyond Models and Decisions: Situating Design through Generative Functions[END_REF][START_REF] Hatchuel | A Systematic Approach of Design Theories Using Generativeness and Robustness[END_REF][START_REF] Hatchuel | Design Theory and Collective Creativity: A Theoretical Framework to Evaluate KCP Process[END_REF][START_REF] Hooge | ORGANISING FOR RADICAL INNOVATION: THE BENEFITS OF THE INTERPLAY BETWEEN COGNITIVE AND ORGANISATIONAL PROCESSES IN KCP WORKSHOPS[END_REF]. Generativity, beyond common and unwieldy analytical metrics for innovation [START_REF] Schepurek | Innovation Performance Measurement: KPIs for Goal-Setting[END_REF] appears to reflect exploration dynamics and probably is an adequate criterion to value design method and routines in organisations specially related to innovation and hence diving into the unknown.

Consequently, we question DT from the routines and design theories perspectives and address the following question: Is DT routine demonstrating a generative power in terms of generated ideas, knowledge but also in terms of collective engagement to explore new disruptive paths at the design and business level?

PURPOSE AND SCOPE

We first propose to elaborate a framework to measure generative power of DT routine when embedded in an organisationthis measurement will be derived from design theory. And we test it on one "reference case", well-known to all experts in DT before testing it on real cases. Our laboratory case is the IDEO's shopping cart design for the ABC Nightline TV documentary. We have chosen to investigate how DT has been used for two separate topicswaste management and turnaround timeon board of aircrafts. The two projects were conducted within a large aeronautics equipment manufacturer, Zodiac Aerospace, by a dedicated team requiring cross-business-units collaboration and challenging dominant designs and product fixation. Our contribution to design management and organisational studies is two-fold. First, we aim at highlighting potential factors contributing or not to the generative power of design thinking and its routine. We carefully look for knowledge structures, practices and artifacts that would or would not elaborate new design paths avoiding lock-ins. Second, we would like to show the limited and unruled generative power of DT and the challenge it faces to have an organisational impact. We will then propose improvements as we believe it could be revised notably its performance related to generativity and transformational power to avoid the method to become just another management fad [START_REF] Deserti | From Design Thinking to Design Culture[END_REF][START_REF] Seidel | Adopting Design Thinking in Novice Multidisciplinary Teams: The Application and Limits of Design Methods and Reflexive Practices[END_REF].

THEORETICAL BACKGROUND

DESIGN THINKING

Beyond the works of [START_REF] Buchanan | Wicked Problems in Design Thinking[END_REF][START_REF] Dewey | Experience and Nature[END_REF] considering design as a liberal art and [START_REF] Simon | Artificial Intelligence: An Empirical Science[END_REF] taking design as a core discipline, the Design Thinking we are interested in is the human-centred problem solving methodology, "fostering creativity" as explained by Hasso Platner in the preface of [START_REF] Plattner | Design Thinking Research[END_REF]. It is inspired by the way traditional designers (industrial designers, stylists, architects) think transposed into a consulting toolbox [START_REF] Brown | Change by Design[END_REF][START_REF] Lockwood | Design Thinking in Business: An Interview with Gianfranco Zaccai[END_REF][START_REF] Powell | How IDEO Designers Persuade Companies to Accept Change[END_REF]. We base our understanding of DT from the works of [START_REF] Bauer | Design Thinking: Epistemic Plurality in Management and Organization[END_REF][START_REF] Brown | Design Thinking[END_REF]ParisTech, n.d.;Stanford, n.d.), which segment DT in three main phases which we will refer as: Launch & Exploratory phase, Conceptual & Prototyping phase and Proposal phase.

DT is now well frame-worked despite its plurality in large firms [START_REF] Carlgren | Framing Design Thinking: The Concept in Idea and Enactment[END_REF][START_REF] Kimbell | Rethinking Design Thinking: Part II[END_REF][START_REF] Kimbell | Rethinking Design Thinking: Part I[END_REF], making it easier to identify when embedded beyond IDEO's service. Its embeddedness and appropriation by the businesses still raises several questions [START_REF] Carlgren | Design Thinking in Innovation, in Practice: The Case of Kaiser Permanente[END_REF][START_REF] Rhinow | Design Thinking: Expectations from a Management Perspective[END_REF] challenging it as the "next competitive advantage" [START_REF] Martin | The Design of Business: Why Design Thinking Is the next Competitive Advantage[END_REF].

DT is framed with the unit of analysis of organisational routines [START_REF] Feldman | Beyond Routines as Things: Introduction to the Special Issue on Routine Dynamics[END_REF][START_REF] Feldman | Reconceptualizing Organizational Routines as a Source of Flexibility and Change[END_REF] by identifying several themesuser focus, problem framing, experimentation and diversityrallying mindsets, practices and techniques hence promoting ostensive and performatives aspects.

QUESTIONING ITS IMPACT

As DT is gradually being used across the industry, since it is seen by executives as a ready-made routine among "ways to look at their businesses because they've seen that the seemingly pragmatic, linear, analytical, quantitative approach of business thinking has not yielded the hoped-for results" [START_REF] Lockwood | Design Thinking in Business: An Interview with Gianfranco Zaccai[END_REF]. It is an attempt for businesses to get away from the exploitation regime, and favour exploration, yet it may not have a long lasting effect as said by Continuum's founder Gianfranco Zaccai in [START_REF] Lockwood | Design Thinking in Business: An Interview with Gianfranco Zaccai[END_REF]. It is a trial to play around with organisational ambidexterity (O'Reilly & Tushman, 2013). DT's methodology has been praised its brainstorming qualities [START_REF] Sutton | Brainstorming Groups in Context: Effectiveness in a Product Design Firm[END_REF], its "knowledge broker" and emulation through empathy values for organisations [START_REF] Hargadon | Brokering Knowledge: Linking Learning and Innovation[END_REF], the latter being corroborated in [START_REF] Carlgren | Design Thinking in Innovation, in Practice: The Case of Kaiser Permanente[END_REF][START_REF] Carlgren | Design Thinking as an Enabler of Innovation: Exploring the Concept and Its Relation to Building Innovation Capabilities[END_REF][START_REF] Carlgren | Exploring the Use of Design Thinking in Large Organizations: Towards a Research Agenda[END_REF][START_REF] Hargadon | Brokering Knowledge: Linking Learning and Innovation[END_REF][START_REF] Seidel | Adopting Design Thinking in Novice Multidisciplinary Teams: The Application and Limits of Design Methods and Reflexive Practices[END_REF]. Despite efforts made to link DT with engineering activities [START_REF] Beyhl | Connecting Designing and Engineering Activities[END_REF][START_REF] Beyhl | Connecting Designing and Engineering Activities III[END_REF][START_REF] Liedtka | Perspective: Linking Design Thinking with Innovation Outcomes through Cognitive Bias Reduction[END_REF], and the role of some artefacts such as prototypes [START_REF] Beyhl | Connecting Designing and Engineering Activities II[END_REF][START_REF] Gabrysiak | How Tangible Can Virtual Prototypes Be[END_REF], we can highlight the naturalistic approach of DT. Users are well studied but do not take an active role in the (re-)design process compared to works of [START_REF] Kristensson | Users as a Hidden Resource for Creativity: Findings from an Experimental Study on User Involvement[END_REF][START_REF] Magnusson | Managing User Involvement in Service Innovation: Experiments with Innovating End Users[END_REF] therefore some design features could perhaps be omitted. Some potential limits are then identified from the depth of the user perspective brought into the design exercise.

In the same line of thought, several works from the design theories' field have offered detailed explanation of features a design process should tackle from a cognitive and a social perspective in [START_REF] Hatchuel | Design Theory and Collective Creativity: A Theoretical Framework to Evaluate KCP Process[END_REF][START_REF] Hooge | ORGANISING FOR RADICAL INNOVATION: THE BENEFITS OF THE INTERPLAY BETWEEN COGNITIVE AND ORGANISATIONAL PROCESSES IN KCP WORKSHOPS[END_REF]: idea generation, knowledge expansion which echoes earlier works on creativity in psychology [START_REF] Amabile | Assessing the Work Environment for Creativity[END_REF][START_REF] Paulus | Idea Generation in Groups: A Basis for Creativity in Organizations[END_REF], on organisation dynamics [START_REF] Dougherty | Bridging Social Constraint and Social Action to Design Organizations for Innovation[END_REF][START_REF] O'connor | Organizing for Radical Innovation: An Exploratory Study of the Structural Aspects of RI Management Systems in Large Established Firms[END_REF][START_REF] Zollo | Deliberate Learning and the Evolution of Dynamic Capabilities[END_REF] whilst stressing the social dimension of design and creativity is key to understand how effective design can be as shown in [START_REF] Akrich | A Quoi Tient Le Succès Des Innovations ? 1 : L'art de L'intéressement; 2 : Le Choix Des Porte-Parole[END_REF][START_REF] Seidel | Using an Online Community for Vehicle Design: Project Variety and Motivations to Participate[END_REF][START_REF] Sosa | Social Change: Exploring Design Influence[END_REF]. In addition to that, the use of C-K Theory [START_REF] Hatchuel | CK Theory: Notions and Applications of a Unified Design Theory[END_REF], has been proven as being a very useful theory to show the extent of a design exercise, fixation effects/path-dependence and depth/width of exploration [START_REF] Agogué | 10 Years of C-K Theory: A Survey on the Academic and Industrial Impacts of a Design Theory[END_REF]. The purpose of this approach is to measure the design effort compared to a given C-K referential done before or in parallel to the experiment to measure the cognitive and social effort linked to the exploration of knowledge and concept spaces, hence revealing the generativity of the process. This methodology has already been applied to the fields of cognitive psychology and technology strategy in the seminal works of [START_REF] Agogué | Orphan Innovation, or When Path-Creation Goes Stale: A Design Framework to Characterize Path-Dependence in Real Time[END_REF][START_REF] Elmquist | The Value of a 'Failed' R&D Project: An Emerging Evaluation Framework for Building Innovative Capabilities[END_REF][START_REF] Le Masson | Why Aren't They Locked in Waiting Games? Unlocking Rules and the Ecology of Concepts in the Semiconductor Industry[END_REF].

Along the same footsteps, we can look at performance criteria from the routines literature, which refers to generativity with similar semantics. Change, flexibility, entanglement and interdepences are explained at the light of routines [START_REF] Feldman | Reconceptualizing Organizational Routines as a Source of Flexibility and Change[END_REF][START_REF] Howard-Grenville | The Persistence of Flexible Organizational Routines: The Role of Agency and Organizational Context[END_REF][START_REF] Jarzabkowski | The Role of Artifacts in Establishing Connectivity within Professional Routines: A Question of Entanglement[END_REF][START_REF] Leonardi | When Flexible Routines Meet Flexible Technologies: Affordance, Constraint, and the Imbrication of Human and Material Agencies[END_REF][START_REF] Spee | The Influence of Routine Interdependence and Skillful Accomplishment on the Coordination of Standardizing and Customizing[END_REF] and as a potential source of novelty [START_REF] Deken | Generating Novelty through Interdependent Routines: A Process Model of Routine Work[END_REF]. A simulation model in [START_REF] Pentland | Dynamics of Organizational Routines: A Generative Model[END_REF], puts forward the generative mechanics of routines inspired from evolutionary models (variation, selection) whilst highlighting the link with macro-level phenomena. [START_REF] Cohendet | THE ROUTINIZATION OF CREATIVITY: Lessons from the Case of a Video-Game Creative Powerhouse[END_REF][START_REF] Cohendet | Always Playable: Recombining Routines for Creative Efficiency at Ubisoft Montreal's Video Game Studio[END_REF] explains how creativity is enhanced and new routines generated by endogenously recombining sub-routines encoded in the business when efficiency guidelines overcome creative flexibility. In other words, this literature field relates to the generativity as the effort for a social group to generate new knowledge or organise for future reference to work on, which relates to a kind of dynamic capability.

For our study, we then choose to relate to generativity in the broadest sense: we will pay close attention to the generation of new ideas, new knowledge areas at an individual and collective level to clarify the forces at work in the DT routine, as we see there is a gap in the literature to explain what makes a creative routine generative in a large firm.

Consequently, we question DT from the routines and design theories perspectives: Is DT routine demonstrating a generative power in terms of generated ideas, knowledge but also in terms of collective engagement to explore new disruptive paths at the design and business level whilst breaking away from pre-existing routines?

METHODS AND RESEARCH SETTINGS

RESEARCH DESIGN

This study relies on an ongoing three year collaborative research started in 2015 with the French aerospace original equipment manufacturer Zodiac Aerospace. This paper is based on the analysis of two main industrial cases of a specific development team (SDT) whose objective is to be as close as possible to an aircraft manufacturer and airlines in order to design innovative offers covering the full range of Zodiac Aerospace portfolio. This peculiar team presents certain flexibility, and managerial patterns that differ from the rest of the Innovation/Design/Research&Technology teams. We benefit from a unique position to understand how a historic aerospace group such as Zodiac Aerospace tries and evolves new organisation settings and innovation methods to face a market where some cards are reshuffled between equipment/system suppliers to win new contracts compared to the traditional established market order.

RESEARCH CONTEXT

The company has a long history of expansion, technological transfers, and innovation from the airships, inflatable boats, seats, electronics equipment, power supply, lighting, cabin lining and lavatories. In a global standardisation movement activities were consolidated and corporate functions have been created to support business units (BU). It is in that perspective that the SDT was created: have a close contact with the market and feed BUs with proposals to further develop. The team is constituted of 8 permanent engineers/designers delegated by BUs for three years maximum, and still dedicate 50% of their time to their unit of origin. They report to a local manager, who actively contributes to the team creativity effort and facilitates discussions with BUs and reports to the group business development director.

DATA COLLECTION

This research is a qualitative study where the first author is hosted at the Group Innovation Direction of Zodiac Aerospace and has full access and regular discussions with the SDT.

In order to understand the routines and the design effort in the DT methodology applied to a design brief or embedded in an organisation, we propose to first start with an analysis of the famous IDEO's Shopping cart well documented in the ABC Nightline show (Case 0). We propose then to use the same analytical lens on the two cases from Zodiac Aerospace. See Table 1 for the collected data.

In case 1, the main author followed the project and its leader since its launch in September 2015 until the final handover discussions with BUs between January and April. A final analysis was reported to the SDT manager, providing a fresh look over this first Design Thinking project. Case 2 started closely before the last handovers of the first project, and was led by a different project leader, who had observed and partially participated to the previous. Some returns on experience where taken on board, yet only minor changes were made to the Design Thinking approach such as a better timing of exploratory phase. No feedback was given by the author to the team on this project.

ANALYTICAL LENS

As introduced in the theoretical background, we will discuss DT routine, and question its impact from a design theory perspective as it provides the broadest sense of the generative power of design effort, and can be transposed to a routine. First, we will refer to the framework elaborated in [START_REF] Carlgren | Framing Design Thinking: The Concept in Idea and Enactment[END_REF] to clearly identify the routine of DT embedded in the organisation (see Table 2). We will refer to it only in the case of Zodiac Aerospace, as for IDEO's case, DT is in its purest form. Second, we will use the design framework in [START_REF] Hatchuel | Design Theory and Collective Creativity: A Theoretical Framework to Evaluate KCP Process[END_REF][START_REF] Hooge | ORGANISING FOR RADICAL INNOVATION: THE BENEFITS OF THE INTERPLAY BETWEEN COGNITIVE AND ORGANISATIONAL PROCESSES IN KCP WORKSHOPS[END_REF] to highlight the design effort in terms of idea generation and knowledge expansion (Table 3) from a cognitive and social perspective.

In order to fill in the design framework four main cells we have executed the following: 1. Cognitive/Idea Generation -A C-K referential was elaborated ex-post based on the exploratory phases of DT as per [START_REF] Agogué | Orphan Innovation, or When Path-Creation Goes Stale: A Design Framework to Characterize Path-Dependence in Real Time[END_REF].

A small bias can be seen here as the referential was not done in real-time, yet it has been proven that the exercise can largely cover what all experts combined can ideate across the semi-conductor industry see [START_REF] Le Masson | Why Aren't They Locked in Waiting Games? Unlocking Rules and the Ecology of Concepts in the Semiconductor Industry[END_REF]. So we feel confident that we did not minor exaggeratedly the DT exercise. 2. Cognitive/Knowledge Expansion -As stated earlier, the C-K referential will help comparing the knowledge solicited by DT and the related cognitive effort. 3. Social/Idea Generation -With the help of data collected, interviews, we observe techniques used and group dynamics to generate and select new ideas. 4. Social/Knowledge Expansion -Along the same line of thought as the previous cell, we report the way knowledge is handled to promote ideas and build consensus around the creative effort, in addition to the fit with stakeholders' knowledge basis and routines.

Involve and support people in a rulebreaking process

Classical method: brainstorming Criteria: well-being, participants satisfaction (i.e. fell comfortable in idea generation) Issues in the literature: production blocking (social anxiousness, perceived expertness, missing recognition) Methods improvements: status auction, electronic brainstorming

Knowledge expansion

Enable relevant knowledge activation, acquisition and production

Classical method: participative workshops Criteria: variety and overlapping Issues in the literature: limited performance because of close-world condition Method improvement: wisdom attitude, learning during the process (on uses, on existing products), competence building (on out of knowledge base)

Manage collective acceptance and legitimacy of rules (re)building

Classical method: consensus building methods Criteria: expert agreement Issues in the literature: conflict, difficulty to accept variety of skills, knowledge distribution Method improvement: no pressure to accept particular perspective, make the customer be positive (prepare acceptance)

RESULTS

We first represent IDEO's case, and to explain to understand how we fill the framework, see Table 4, Table 5 andTable 6, which compiles all three cases. Afterwards, Zodiac Aerospace's cases are presented, also taking into account the organisational routine dimension, followed by our analysis.

TEST CASE ON IDEO'S SHOPPING CART (IDEO)

We proposed to test our analytical framework on the well-known case of IDEO's team working on a new shopping cart by using there DT methodology. The case configuration here is different from Zodiac Aerospace as DT is not embedded in any firm, it is an external intervention with little feedback and promotion to potential client and users.

IDEA GENERATION Cognitive dimension

The team lead by Peter Skillman, with David Kelley's supervision and authority guide the eclectic group composed of engineers, designers, linguist and marketing etc. Themes for the groups are given following the deep dive, with an emphasis on overall safety/theft; they reflect a certain limitation in the concept exploration, closing the path for other designs. For instance, at one point the leader says "If [the cart] doesn't nest, we don't have a solution" Peter Skillman. The generative power is rather low despite the combination of professionals, and user input assimilated to experts ("The trick is to find these real experts. The people who are really getting the info are out in the field meeting with people." David Kelley).

Social dimension

The brainstorming has strict rules and the leaders have an important role in guiding the exercise, all members have their say, and propose their ideas freely to discuss their attributes. A vote is organised to narrow down the number of ideas generated, and recombination of concepts' features happens at the very end for the final design proposal. However, beyond the team level, concept legitimacy is partially given thanks to user empathy: there is a surprise effect when shop assistants are confronted to the new design as it may redefine their whole work and traditional routine: e.g. the hand-held scanner can be seen as a threat to the cashier's position at that time. This performative aspect is not well handled by DT, due to the reduced exploration.

KNOWLEDGE EXPANSION Cognitive dimension

Team members are encouraged to go out and meet all traditional users whilst acknowledging some alternative uses when the cart is taken out of its supermarket environment (barbecue, carrying). Yet, some rules inherent to the cart and the supermarket are not challenged nor identified in the process: What about using the cart up to the car's boot? Following the user's shopping experience down to the refrigerator? Should the provided plastic bags be considered as the sole option? Etc. The user focus, expands the members' knowledge yet, and his immediate concerns whilst letting a whole knowledge space hidden.

Social dimension

All members share their knowledge through stories, drawings and prototypes, allowing everyone to be on the same level despite their different background.

The last stagepromotion/testing of the designends up on a weak note: it considers that the design as it is, a detailed actionable prototype, should entail a development project for a cart manufacturer, but many aspects still remain unanswered: strong diversification needed from the cart manufacturer to start working with more plastic materials, electronic devices to be closer to supermarket operations, and marketing value and fitness goes beyond 'user consultation' as a whole ecosystem of routines and values are to be elucidated.

Finally, we would like to quote Kelley, who partially reveals the conception of DT when applied or embedded to a firm: "It is one thing to be able to do a product once in a while, but if you can build a process where you can routinely come up with great ideas. That's what the companies really want". He calls for creativity systematisation and exploration dynamic of the organisation by emphasising the conceptual effort without specifying generative mechanism or organisational compatibility.

SDT CASES (ZA1, ZA2)

SDT's two project leaders were trained to DT in their studies or career. We go through the main themes of the routine as described in Table 2 [START_REF] Carlgren | Framing Design Thinking: The Concept in Idea and Enactment[END_REF]: User-focus, Problem Framing, Visualisation, Experimentation, and Diversity. Due to time constraints and re-consideration of their own work as the design exercise move forward the team leaders and the SDT manager decided to have some overlap with the main three movements of DT, see below, in Figure 1.

Problem framing

The projects definition was a collective choice made at SDT after a year of work, and weekly creativity sessions on different topics chosen by team members. The topics were selected for enabling BUs to tackle users' issues whilst exchanging with fellow units.

User-focus and Diversity

The exploratory phase consisted of background research, collecting data from BUs, and topic's stakeholders. The result was presented in the form of a mind map of the documented topics in alignment with overall product portfolio. The report is shared to participating BUs for knowledge gain, and to have feedback for SDT to gear the DT focus.

Problem framing, experimentation and visualisation

The conceptual phase is made of several creativity sessions between SDT members and occasionally invited BUs or corporate employees, and in case 2 a group of engineering students trained to DT. Those sessions brought around 200 ideas that are classified and sometimes merged together and reformulated when similar. Ranking follows criteria reflecting: alignment with business strategy, customer value, added value compared to the existing and user value. In parallel SDT added a subjective note representing how far-fetched ideas are. A final shortlist follows: a top 10 along with specific lists of 5 to 10 concepts for each BU, i.e. suitable for their specific product portfolio.

Visualisation and experimentation

Prototyping happens quite early in the process, during the first sessions, drawings are made, discussed with others, and low fidelity prototypes are made on the spot. During the concept development and iterations between SDT and BUs, several 3D renderings are discussed with engineering/marketing/design teams.

Problem (re-)framing and another theme in the DT routine: social acceptance

The multi-BU workshop is a specific creativity session held after the concepts ranking and first development iteration. It is the first time SDT presents their concepts. Representatives of the concerned BUs attend and work around a tailored theme considered as the core topic by SDT's members and manager.

Finally, the promotion to BUs is carried over several months to pitch the ideas with physical meetings, multiple design iterations on the presented concepts whilst taking into account comments from the several parties. This step goes beyond simple feedback. Indeed, SDT has to 'sell' internally their proposals for BUs to further develop. SDT is considered to succeed when a BU takes the lead on a proposal, and one metric, yet without a given objective, is the number of provisional patent applications.

SUMMARY OF RESULTS

CASES' INTERPRETATION: LIMITED COGNITIVE AND CONCEPTUAL EXPLORATION LIMITING ORGANISATIONAL IMPACT

KNOWLEDGE LEFT ON A SIDE

The exploratory and the conceptual phases to study knowledge clusters directly pointed by users, some topics out of user's scope where deliberately left on a side, like in the case no.2, as some areas where considered out of Zodiac Aerospace's scope (business held directly by airport operators) and others not even mentioned. With the help of the C-K referential, we revealed white spaces, which show that compared to the chosen design paths and knowledge areas, there is up to 60% of the knowledge that was solicited.

In case 1, for instance, waste in the aircraft was not apprehended from another angle: bacteria and viruses; it was partially revealed during the preliminary exploratory phase, but quickly discarded as not being raised by users. In addition to that, "time-constraint" and "not having the right tools" was raised across case 1&2, yet it does not prevail from contouring missing knowledge, not directly seen through users.

User-focus promotes primary concerns, or sometimes secondary, but other constraints are omitted whereas they could open new paths far from traditional design. The new knowledge that is constituted has the following pattern (see Figure 2):

-User empathy provides elements to revise existing designs and reconsider close functions without challenging their nature -Distant knowledge is reached only during 'What-ifs?' sessions, which by reshuffling the card allow members to imagine different environments, use cases and designs calling for personal knowledge extracted from fiction or for recurrent group ideas (e.g. the 'sushi-belt' for any purpose, robots, or a "magic thing that makes life easier" etc.). Some realistic concepts were shortlisted and require further investigation for BUs for having changed the ecosystem. These ideas that appear in a serendipitously fashion, echoes works of [START_REF] Von Hippel | CROSSROADS-Identifying Viable 'Need-Solution Pairs': Problem Solving Without Problem Formulation[END_REF] on need-solution pairs.

Finally, the strong user-focus reveals a pre-fixation in the design process: a preconceived ecosystem. The users do inform on the existing ecosystem, yet DT takes it for granted. DT seems to have encoded in its routine that the ontology of the problem is invariant; knowledge is not fundamentally re-ordered during the design exercise, as shown in Figure 2.

A CERTAIN PATH-DEPENDENCE

In correlation with knowledge structure we have observed a certain path-dependence due to the restrictions of user-focus and business scope. In Figure 3, the dotted lines and circles represent the unrevealed areas, most of the knowledge developed the hereditary path we see on the left which stays close to dominant designs, some deviations branch out of the main path showing how user focus and experimentation opens optimisation and recombination possibilities over existing designs. Among distant concepts, in the "unexplored" area, some ideas where highlighted during creativity sessions but mostly forgotten because requiring further research was needed to appreciate the concepts with the relevant missing knowledge.

As some particular knowledge items are not collected, there is no "push" force to neither create extreme design paths nor probe the ecosystem. Only some "what-ifs" scenarios built on shaky grounds break existing rules but are hardly selected for being out of the preconceived problem framing. The SDT admitted that they remained at a very conceptual level and that discussions with BUs were complex since they were requesting more technical details and customer value proof and struggled to articulate interdependence of the proposal with the existing state of the art. Despite difficulties, the SDT have opened the BUs' eyes to user concerns and potential improvements.

The SDT who seeks at shaping valuable proposals bridging aircraft manufactures/airlines and Zodiac Aerospace know-how, seems to struggle to match the The routine implemented by SDT wants to break the existing ostensive aspects of the overarching business routines such as the business scope, and techno-structure imposed which reflect how products are designed in partially isolated clusters. This segmentation is historically linked to serial acquisitions, the group standardisation, and to the fact that engineering is ruled by the aircraft manufacturer along with airline specific demands, following Air Transport Association chapters which siloes equipment and systems.

Consequently, the performances developed by SDT face the exploitation wall raised by daily BUs operations, hence facing questions from BUs' contacts: "Who is paying for the development work? Who is paying the intellectual property? I don't have a budget line for this action." Questions that have shy answers, in case 1 only one budget line for the coming financial year of one BU reflects the will to study one proposed concept. SDT's exploration and BUs' exploitation have different temporalities.

When facing reluctance, SDT choses to protect worthwhile ideas with provisional patents with sponsorship from group corporate management, thus complexifying SDT's action, as BUs willing to develop may be hard to find and to bend to perform the work.

DT by providing a list of concepts that are pre-fixated by the ecosystem actually fits pretty well with the BUs' ontology, yet there is a misfit when DT provides borderline concepts revising design rules, knowledge and organisational dynamics, its technostructure and settled routines. Those issues are apparently not controlled in the DT methodology.

DISCUSSION AND CONCLUSION

Our study shows that DT has a limited generative power due to several factors:

-Knowledge collection through user focus draws a design path closely ramified from existing dominant design whilst omitting and not controlling other paths challenging the design ecosystem -The search for users information feeds reveal a hidden bias where the ontology appears invariant by default and encoded in DT routine -These fixations make the impact of novel edgy concepts for the pre-fixated ecosystem effortful as the rule breaking process is hard to understand for the organisation.

As a routine DT is not showcasing a strong generative power and appears to misfits the organisation.

Generativity is not an end in itself, as extreme cases of generativity would imply extreme flexibility for the organisation and market. DT does an incredible work at exploring the user knowledge and exploiting for enhanced or new functions it but some of its generativity appears uncontrolled. As the ecosystem is pre-fixated, DT omits the possibility of using technology to modify the environment, modulate the organisation and its routines to perform the design exercise. Problem formulation is perhaps too narrowed and should embrace a larger scope as concept promotion is challenging.

One axis of development of DT would be to refine its problem formulation and extreme user research steps. Preliminary studies should enlarge the perimeter to alternative use cases to address the possible alteration of the design ecosystem and the organisational implications. This process should not be left to "What-If" scenarios which only provides need-solution pairs [START_REF] Von Hippel | CROSSROADS-Identifying Viable 'Need-Solution Pairs': Problem Solving Without Problem Formulation[END_REF] easily discarded or disturbing for final developers as its origin is ill-defined. This openness at the start should be stopped at some degree and should take into account organisational barriers to gain in design fluency when it comes to challenge existing rules.

As we mentioned, knowledge structure and path-dependence for concepts appear to be limiting factors for DT to go full scale in the organisation and emphasise, stimulate the creativity of BUs. The "Change by design" promise [START_REF] Brown | Change by Design[END_REF] is not kept as its own uncontrolled generativity. User-empathy does not seem good enough to articulate interdependences in a large firm at a cognitive and social level.

Overall, if a creative routine should be designed to bridge the gap between exploration and creativity, we would be looking at phenomenon such as the one of a messenger RNA conveying genetic information from DNA to the ribosome for expression of encoded genes. A creative routine, would feed from pools of knowledge, a given ecosystem, encode the essence of it, into several performances and then reinterpret these within the organisation, and if possible with variations, selections, if we refer to [START_REF] Pentland | Dynamics of Organizational Routines: A Generative Model[END_REF]. Design Thinking still has a few features to articulate and develop to succeed its organisational embedding.

Figure 1 -

 1 Figure 1 -SDT's DT methodology

Figure 2 -

 2 Figure 2-Knowledge expansion pattern with no re-ordering

Figure 3 -

 3 Figure 3 -Concept development pattern

  pushing existing design to their boundaries by taking into account the user experience but remaining the general "product known environment" level of performance requested by BUs. The effort required goes beyond the pure proposal of creative ideas.

Table 1 -Data description

 1

		Case 0	Case 1	Case 2
	Description	IDEO's Better	ZA Better Waste	ZA Optimised
		Shopping Cart	Management for the	Aircraft Turnaround
			aircraft	Time
	Project length	One week	6 months	8 months
	Organisational	IDEO team	ZA mixed background (several BUs, working
	entities involved	(designers and	groups of designers and engineers)
		engineers)
	Data sources	ABC Nightline TV	All documentation produced during the project
		documentary	and formal/informal discussions with project
			participants (12 interviewees)

Table 2 -Characteristics and framework in

 2

[START_REF] Carlgren | Framing Design Thinking: The Concept in Idea and Enactment[END_REF]

Table 3 -Analytical framework and examples of criteria value Cognitive Social Idea generation Cover the whole conceptual potential of the initial concept ("problem formulation")

 3

	Classical method: brainstorming
	Criteria: fluency
	Issues in the literature: limited expansions
	(similarity, based on limited knowledge base)
	Method	improvements:	mix	divergent
	thinking/convergent thinking personalities,
	trained facilitator (filtering and orienting
	divergence)

Table 4 -Summary of results -LAUNCH AND EXPLORATORY PHASES

 4

	Case			Cognitive			Social
	Idea	-	Topics opening an innovation field	-	New topic to work upon with eclectic
	generation		identified by team leaders: better shopping	group
	IDEO	-	cart Several themes are quickly identified for	--	Members have a history of DT practice Everyone feels concerned by the project as
			exploration: safety, shopping practices,	they all have some experience and already
			checkout, searching products		have ideas of improvements
		-	The Waste Management topic is identified	-	The team had already briefly explored the
			as major issue on board of aircrafts		topic
		-	Business Units are somehow related to the	-	DT was seen as a strong value-add by the
	ZA1		issue and could contribute to it		team and the manager to try another method to promote SDT's work to the
							whole group
							-	Some concepts are extracted from business
							units revealing some isolated ideas
		-	The Turnaround Time subject is seen as a	-	The team had already briefly explored the
			critical point for airline operations where	topic
			Zodiac Aerospace can contribute through	-	DT had been used in the previous case, the
	ZA2		their equipment			team was rather happy with experience
							and took into account some points to
							improve (quicker exploration, better
							technical details in proposals)
	Knowledge	-	Team leader encourages to go out for the	-	A first discussion helps to define a set of
	expansion		deep dive and meet the users, seen as	themes to work, consensus is built by
	IDEO		experts on the field			sharing experiences
		-	'Extreme users' are investigated		-	Knowledge is carefully shared between
							members
		-	Following DT methodology, team	-	Team leaders encourage to share the
			members are encouraged to collect	acquired knowledge quickly between each
			information from their desk and meet with	other and redirect towards other potential
	ZA1		waste	stakeholders	ranging	from	interviewees or topics when something is
			passengers to airports			felt worth investigating further
		-	The report raises interest among business	-	A full report is issued and shared with
			units' contacts			business units
		-	Following DT methodology, team	-	Team leaders encourage to share the
			members are encouraged to collect	acquired knowledge quickly between each
			information from their desk and meet with	other and redirect towards other potential
			all stakeholders impacted by turnaround	interviewees or topics when something is
	ZA2		time ranging from passengers to airports	felt worth investigating further
			operations			-	Some knowledge areas to discarded for
		-	The report raises interest among business	being out of the company's business scope
			units' contacts			-	A full report is issued and shared with
							business units

Table 5 -Summary of results -CONCEPTUAL & PROTOTYPING PHASES

 5

		Case			Cognitive	Social
	Idea		-	The team is fragmented in groups to work	-	All members come up with many ideas,
	generation			a selected topics following exploratory	and have to be refocused on some selected
				phase input		topics chosen by team leaders to avoid
		IDEO	-	Concepts are reviewed, voted, and	dispersion and stop the ideation
				recombined at a later stage to convert into	-	High involvement of members
				a single solution	-	Some existing design rules are kept
						constraining some wild ideas
			-	The team organises several creativity	-	High involvement of members with once
				sessions,	mixing	drawings,	rapid	in a while participants external to SDT and
		ZA1		prototyping, around selected themes formulated after the exploratory phase	-	directly concerned by the project A final workshop is organised with all
			-	All concepts are reviewed and ranked	business units' contacts to recombine over
			-	A shortlist of ideas is issued	already elaborated concepts
		ZA2	-	Identical to ZA1	-	Identical to ZA1
	Knowledge		-	All ideas are carefully discussed and tested	-	Team leaders had to reframe the problem
	expansion	IDEO		through tacit knowledge produced	and stress knowledge areas previously identified to further develop the concepts
			-	All ideas are discussed and iterated over	-	No specific intervention from leaders or
				between members	manager to expand knowledge to other
			-	Some deception was felt by SDT members	areas
		ZA1		after the multi-BU workshop, they expected to have more breakthrough ideas	-	Multi-BU workshop is organised around two themes already worked on by SDT
			-	Concepts are ranked and grouped to match	after presenting exploratory phase output
				known product lines, and business units'	and shortlist of ideas
				activity
			-	All ideas are discussed and iterated over	-	Identical to ZA1
				between members
		ZA2	-	Concepts are ranked and grouped to match
				known product lines, and business units'
				activity

Table 6 -Summary of results -PROPOSAL PHASE

 6

		Case		Cognitive		Social
	Idea		-	The final concept is refined through	-	The final solution is presented to some
	generation			recombination of best features in the		users in the supermarket environment for
				theme, no further expansion nor		feedback, and tested with team members
		IDEO		comparison to other solutions		on the field
					-	For shop assistants, a surprise effect is
						noticed suggesting the value chain is
						modified
			-	Some improvements are made to some of	-	The shortlist of selected concepts are
				the shortlisted ideas selected by business		promoted to business units, and a
				units		secondary shortlist is presented in line
		ZA1		New renderings, more technical details		with their product portfolio
				have to be provided	-	A stretch from existing design but would
						require some level of rule breaking,
					-	Poor enthusiasm from business units
		ZA2	-	Identical to ZA1 for the contacted business units	-	Identical to ZA1 for the contacted business units
	Knowledge		-	The hand scanner seems to be the only	-	No further development axis is highlighted
	expansion	IDEO		feature that remains to be worked on, but very little concern is shown on all the
				knowledge remaining
			-	The team leader visits business units and	-	Provisional Patent Applications are
				organised several meetings to discuss		considered to encourage business units to
				iterations over selected concepts		work on the solutions
			-	More technical detail is requested	-	Budget lines are missing for business
		ZA1	-	Business units are in a "wait and see"		units, they do not seem to have enough
				position, the value is not yet fully grasped		resources available to implement
			-	The stretch from their dominant design	-	Working between business units is
				requires a better acquaintance of other		considered as rather complicated exercise
				business units
		ZA2	-	Identical to ZA2 for the contacted business units	-	Identical to ZA2 for the contacted business units

Table 7 -Design effort a cognitive/individual perspective Cognitive perspective

 7

	Concept coverage	-	Up to ~60% coverage
		-	Very path dependent and some sideways exploration with the help of with
			"What If scenarios" in conceptual phase, challenging existing designs
	Knowledge	-	Up to ~60% of knowledge is presented
	expansion		(Case1: areas not even in the radar ; Case2: white spaces were identified and
			omitted)
		-	Tacit knowledge with prototyping
		-	Main acquired knowledge comes from user empathy, other knowledge such as
			new technologies or new functions are scarce
		-	New distant knowledge appears almost serendipitously with need-pair solutions
		-	User knowledge is interpreted into a design brief


Mélissa Dali

Olivier Rossel

David Guiraud

Ieee Embs Member

Numerical simulation of multipolar configuration and prepulse technique to obtain spatially reverse recruitment order

In the context of functional electrical stimulation of peripheral nerves, the control of a specific motor or sensory functions may need selective stimulation to target the desired effect without others. In implanted stimulation, spatial selectivity is obtained using multipolar CUFF electrodes with specific spread of the current over each contact. Furthermore, electrical stimulation recruits large fibers before small ones, whereas the targeted function could be elicited by a specific fiber type i.e. fiber diameter.

In our work, numerical simulations were used to investigate the combination of multipolar configuration and prepulses, in order to obtain spatially reverse recruitment order. Multipolar stimulation provides efficient spatial selectivity, whereas subthreshold prepulses were used to reverse recruitment order with a reasonable increase of the injected charges. We compared several selective configurations combined with prepulses to show that some are able to guarantee both the spatial selectivity while one fiber's diameter can be preferentially activated.

I. INTRODUCTION

Functional electrical stimulation (FES) is a technique used to restore sensory or motor functions in case of neurological disorders for instance due to spinal cord injury, trauma or stroke. A nerve has multiple targets: to independently activate muscles, a control of activation by spatial selectivity of axons is required. Sunderland [START_REF] Sunderland | Nerves and nerve injuries[END_REF] published data about fascicular organization in peripheral nerves in distal regions, other investigations exist in the upper limb (ulnar nerve) [START_REF] Jabaley | Internal topography of major nerves of the forearm and hand: a current view[END_REF], and lower limb (femoral nerve) [START_REF] Kenneth J Gustafson | Fascicular anatomy of human femoral nerve: Implications for neural prostheses using nerve cuff electrodes[END_REF]. In implanted stimulation, multicontact electrode such as CUFF electrodes are commonly used to activate the desired population of axons within the nerve. Numerical studies and experimentation have been carried out with CUFF electrodes to find configurations which best achieve spatial selectivity. Authors presented different configurations such as longitudinal tripolar [START_REF] Veraart | Selective control of muscle activation with a multipolar nerve cuff electrode[END_REF], [START_REF] Thomas N Nielsen | Transverse versus longitudinal tripolar configuration for selective stimulation with multipolar cuff electrodes[END_REF], field steering [START_REF] Sweeney | A nerve cuff technique for selective excitation of peripheral nerve trunk regions[END_REF] [19] transverse tripolar [START_REF] Deurloo | Transverse tripolar stimulation of peripheral nerve: a modelling study of spatial selectivity[END_REF], [START_REF] Thomas N Nielsen | Transverse versus longitudinal tripolar configuration for selective stimulation with multipolar cuff electrodes[END_REF] among which Transverse Tripolar (TT) seemed to be the most selective one [START_REF] Guiho | Toward complex multipolar selective neural stimulation[END_REF].

Another important issue in peripheral nervous system stimulation is fiber diameter selectivity. Unlike Natural Recruitment Order (NRO), conventional stimulation with a rectangular current pulse preferentially recruits large motor fibers over small ones. This phenomenon termed Inverse Recruitment Order (IRO) may cause undesirable effects such as muscle fatigue: rapid fatigable motor units innervated by large fibers are recruited before slow fatigue resistant motor units innervated by small fibers. Autonomic functions can also be specifically addressed by axons of a given diameter that is not the larger ones and thus may recquire also for this type of selectivity. Several approaches exist to achieve this goal: anodal block [START_REF] Brindley | A technique for anodally blocking large nerve fibres through chronically implanted electrodes[END_REF], high frequency block, slow rising ramp pulse [START_REF] Hennings | Selective activation of small-diameter motor fibres using exponentially rising waveforms: a theoretical study[END_REF] and subthreshold prepulses [START_REF] Grill | Inversion of the current-distance relationship by transient depolarization[END_REF]. Subthreshold prepulses change the excitability of nerve fibers by increasing the activation thresholds of large fibers more than smaller ones. This technique has been validated in vivo on sciatic nerve of cat [START_REF] Grill | Inversion of the current-distance relationship by transient depolarization[END_REF], and rat [START_REF] Van Bolhuis | A nerve stimulation method to selectively recruit smaller motor-units in rat skeletal muscle[END_REF]. Simulation of subthreshold prepulses were performed with point source cathode [START_REF] Grill | Inversion of the current-distance relationship by transient depolarization[END_REF], [START_REF] Deurloo | The effect of subthreshold prepulses on the recruitment order in a nerve trunk analyzed in a simple and a realistic volume conductor model[END_REF] and ring longitudinal tripole (LTR) configuration [START_REF] Deurloo | The effect of subthreshold prepulses on the recruitment order in a nerve trunk analyzed in a simple and a realistic volume conductor model[END_REF]. To our knowledge, in the context of subthreshold prepulses stimulation no studies investigate other multipolar configurations such as TT with a deeper analysis on the spatial selectivity. In this context, the objective of the present study is to obtain the recruitment of fibers with a specific diameter in a specific target area by combining simulations of both multipolar stimulation and prepulse approaches.

II. METHODS

A 2-part process is used to determine nerve activation. First, we computed the potential field distribution produced by electrode through the nerve, then we applied this potential to a mammalian model of myelinated fibers to determine if activation occurs.

A. Volume conductor model

The potential field distribution generated by cuff electrode was obtained by solving Poisson's equation within the 3D model of the nerve under quasi-static conditions. The 3D Finite Element Model (FEM) of a cylindrical nerve and cuff electrode was implemented on COMSOL Multiphysics (COMSOL Inc. Burlington, MA). The nerve model was composed of a single fascicle with a 2.4 mm diameter, a perineurium and an epineurium with a 2.8 mm diameter surrounded by a layer of saline solution with 3 mm diameter. The perineurium thickness was set to 3% of the fascicle diameter according to [START_REF] Yanina Grinberg | Fascicular Perineurium Thickness, Size, and Position Affect Model Predictions of Neural Excitation[END_REF]. Tissue electrical properties were based on [START_REF] Choi | Selectivity of multiplecontact nerve cuff electrodes: a simulation analysis[END_REF]. Endoneurium was assumed to be anisotropic : conductivity were 0.06 S/m in longitudinal direction (Z) and 0.083 S/m in transverse direction (XY), the conductivity of perineurium was 0.0015 S/m, that of epineurium was 0.083 S/m and that of saline was 2 S/m. A cylindrical (3mm diameter) CUFF electrode with 12-pole (3 rows with 4 contacts) was modeled around the nerve. Adjacent ring separation was set to 1.5mm, contacts on a ring are placed at 0 • , 90 • , 180 • and 270 • (Fig. 1). Poisson's equation was solved using COMSOL, the resulting potential was transferred to Matlab and interpolated along 333 fibers sampled on a grid (Fig. 1). Spacing in the radial direction (X,Y) was set to 0.1mm. Spacing on longitudinal direction (Z) depends on internodal distance thus on fiber diameter.

B. Nerve fiber model

To represent motor axon response to stimulation, we implemented a cable model of axon based on [START_REF] Donald R Mcneal | Analysis of a Model for Excitation of Myelinated Nerve[END_REF]. Instead of Frankenhauser equations (amphibian model) we used CRRSS ones [START_REF] Chiu | A quantitative description of membrane currents in rabbit myelinated nerve[END_REF] (mammalian model) to describe non linear membrane dynamics. CRRSS equations were adapted to 37 • C [START_REF] Sweeney | Modeling of mammalian myelinated nerve for functional neuromuscular stimulation[END_REF]. In the model of axon, the myelin is considered as a perfect insulator. Four axons with different diameters were simulated: 5µm, 10µm, 15µm and 20µm. The central node of fibers was set under the central ring. Thresholds were then determined for all fibers inside the nerve.

C. Current settings

To get both spatial selectivity and a preferential activation of, in our example, 10µm fibers, we optimized current spreading between contact over time and pulse waveform with prepulses. First step was to determine an efficient current distribution on the contacts to obtain spatial selectivity. Second step was to set duration of prepulses. A long depolarizing prepulse increased the activation threshold of large fibers close to the cathode. Third step was to set number of prepulses. Our simulations showed that increasing number of prepulses expanded the area of inactivation and push back activation of large fiber further in the nerve. Duration and number of prepulses were optimized for the targets used in this study (data not shown). We used current configurations composed by 4 stepped prepulses (PP1 to PP4) followed by a depolarizing pulse (Act P) and a single pulse in TT configuration was used as current configuration control. (Fig. 2). With this last configuration, only spatial selectivity is achieved in IRO.

1) multipolar configuration: First configuration ("Conf 1", current configuration control) was a single pulse of 300µs duration with TT configuration i.e. one cathode 90 • , and 2 anodes at 0 • and 180 • (Fig. 1). Second configuration ("Conf 2") was composed of 4 prepulses with TT configuration (PP1 to PP4, Fig. 2) and one activating pulse (ACT P, Fig. 2) with TT configuration. Third configuration ("Conf 3") was composed of 4 prepulses (PP1 to PP4, Fig. 2) with LTR configuration, i.e., 4 cathodes in 0 • , 90 • 180 • 270 • with equal spreading of the current, and anodes on the external rings (i.e. all external contacts were short-circuited). The prepulses were followed by an activating pulse (ACT P, Fig. 2) with TT configuration.

2) Prepulse and pulse configuration: We increased number of prepulses, four instead of two compared to Grill [START_REF] Grill | Inversion of the current-distance relationship by transient depolarization[END_REF] and Deurloo [START_REF] Deurloo | The effect of subthreshold prepulses on the recruitment order in a nerve trunk analyzed in a simple and a realistic volume conductor model[END_REF] to further elevate thresholds of large fibers close to the cathode (i.e. inactivate them) while activating fibers with smaller diameters. Increasing more than 4 prepulses was not needed according to our simulations. For "Conf 2" and "Conf 3", first prepulse duration was set to 500µs [START_REF] Grill | Inversion of the current-distance relationship by transient depolarization[END_REF]. We however reduced duration of following prepulses to 200µs to limit the injection of charge. The duration of activating pulse was 200µs. To elicit medium fibers of 10µm, we set prepulse parameters to reduce activation of 15µm and 20µm fibers diameter. First prepulse was set to be at 95% of the threshold of the first fiber of 15µm diameter activated, the same method is used for prepulse 2, 3 and 4. Activation pulse was observed for value between -1mA and -3.5mA on the cathode. For "Conf 1" (Fig. 2), duration of the pulse is set to 300µs and current varied from -1mA to -1.7mA on the cathode.

D. Data analysis

We focused on the maximum activation for fibers with 10µm diameter. To quantify the effect of pulse shape and multipolar configuration on spatial and fiber diameter selectivity, we defined selectivity index for a target area on the cross section of the nerve. This target had an ellipsoidal form, centered on the top of the nerve (see Fig. 1). We varied the length of minor and major axis from 2 to 6 mm with a step of 0.1 mm for the major axis and 0.8 to 1.4mm with a step of 0.05mm for minor axis. For each diameter D, we defined 2 percentage of activation, in the targeted zone n T A (D), and in the non targeted zone n N T A (D). We defined a selectivity index as the difference between n T A (D) and n N T A (D) :

SI(D) = n T A (D) -n N T A (D) (1)
The optimal current is determined as the amplitude of "Act P" giving the maximal SI of 10µm fibers diameter.

Comparisons are given with this optimal current.

III. RESULTS

A. Activation order

The threshold of activation of each fibers for 4 different diameters and 3 configurations, is determined using dynamic nerve fiber model (Fig 3). For "Conf 2" and "Conf 3", we represented current needed for the activating pulse (ActP). Value of prepulses are listed on table I. For Conf 1, as expected, fibers with large diameter, i.e. 15µm and 20µm, were preferentially recruited before fibers with smaller diameter i.e. 5µm and 10µm.

Stepped TT prepulses ("Conf 2") increased thresholds, es- pecially for large fibers and reversed the current distance relationship close to the cathode as described in [START_REF] Grill | Inversion of the current-distance relationship by transient depolarization[END_REF], [START_REF] Deurloo | The effect of subthreshold prepulses on the recruitment order in a nerve trunk analyzed in a simple and a realistic volume conductor model[END_REF]. However, activation of large fibers still occurs far from the cathode. In other words, small fibers were preferentially recruited and large fibers inactivated but this effect is limited to the proximity of the cathode with still activation of large fibers further. The "Conf 3" configuration is the most efficient to inactivate fibers of 15 and 20µm diameter over the whole nerve; even if a small amount of fibers of 20µm diameter were still activated at the extreme periphery of the nerve.

To sum up, "Conf 1" activated in IRO for current varying from -1mA to -1.7mA, "Conf 2" activated fibers in NRO but large fibers were activated further in the nerve for current varying from -1mA to -3mA. "Conf 3" activated fibers in NRO with minimal activation for the large fibers over the whole nerve, for current of the activating varying from -1mA to -3mA with a spatial selectivity for the 10µm targeted fibers.

B. Selectivity index

Selectivity index (Eq 1) is computed for various targeted zones and range of current. We show the mean value of selectivity index of the optimal index (for 10µm fibers) found for each targeted zones.The bar chats in Fig. 4 represents this mean value for each configuration and each diameter. Fibers with 15 and 20µm diameter were most often recruited with "Conf 1": respectively 88.2% (standard deviation, std=9.8%) and 91.9% (std=5.3%) of activation, fibers with 10µm diameter were recruited with a mean of 71.8 % (std=17.0%) . "Conf 2" and "Conf 3" had better selectivity index for fibers of diameter 10µm : 83.6% (std=6.5%) and 83.9% (std=6.2%) respectively. The difference between "Conf 2" and "Conf 3" comes from selectivity index of large fibers: axons with 15 and 20µm diameter had higher selectivity index for "Conf 2": respectively 57.3% (std=6.6%) and 45.8% (std=10.0%) whereas selectivity index decreased with "Conf 3" : 34.2% (std=7.2%) and 12.2% (std=5%) respectively. Selectivity index is not significant for axons with 5 µm diameter for all configurations : 15.0% ("Conf 1"), 35.4% ("Conf 2") 38.8% ("Conf 3").

IV. DISCUSSION

In this study, the combination of prepulse technique with multipolar configuration compared to a single pulse on TT configuration has been investigated by numerical study. As expected, the single TT pulse ("Conf 1") activates large fibers first under the cathode. Using TT prepulses ("Conf 2") activates large fibers further in the nerve with higher stimulation thresholds whereas it inactivates large fibers close to the cathode. With "Conf 3", it is possible to elicit activation of 10µm fibers diameter without activating large fibers of 15µm and 20µm diameter in a restricted target close to the cathode. "Conf 3" was designed to be the best configuration that elicited mainly 10µm fibers, even if some activation of large diameter fibers in the periphery occurs. On the one hand, the effect of external anodes was considered [START_REF] Deurloo | The effect of subthreshold prepulses on the recruitment order in a nerve trunk analyzed in a simple and a realistic volume conductor model[END_REF]: Block is possible with small contact spacing, when hyperpolarisation occurs close to the central node (node closest to cathode). Therefore, in our model, to block large fibers, longitudinal contact spacing was set to 1.5mm, same size of internodal distance of 15µm fibers. On the other hand, the 4 first prepulses increase the level of activation of all the fibers of 20µm within the nerve contrary to "Conf 2" that limits this increase to axons close to the cathode. It could be explained by small axial gradient inherent to TLR configuration. Finally, last stimulation pulse with TT configuration, can be thus selective both as regard fiber diameter and location.

For all configurations, activation of 5µm fibers was not very significant (less 38.8%) and cannot be managed separately, but as they have higher thresholds they are less activated in all configurations. Prepulses duration were set to increase thresholds of fibers with large diameter. We used a duration of 500µs for the first prepulse (PP 1) according to the study of Grill [START_REF] Grill | Inversion of the current-distance relationship by transient depolarization[END_REF]. We found that is was enough to set following prepulses to 200µs (PP2, PP3 and PP4) to elevate thresholds. Contrary to previous works, this leads to less injected charges with the same effect. Indeed simulations (not presented here) show that longer prepulses except the first one, is not needed.

The neuron model used was the same as [START_REF] Grill | Inversion of the current-distance relationship by transient depolarization[END_REF], confirmed by experimental work. In our study, we assumed that nodes of Ranvier were aligned with the contacts. Simulations of Deurloo et al. [START_REF] Deurloo | The effect of subthreshold prepulses on the recruitment order in a nerve trunk analyzed in a simple and a realistic volume conductor model[END_REF] on longitudinal tripolar configuration shown that the effect of subthreshold persisted with any nodal position compared to the cathode, resulting in an increase of thresholds.

V. CONCLUSION

The results of this numerical study showed that we could obtain spatial reverse recruitment order using of multipolar configuration combined with prepulses. We are currently investigating multifasicular nerve together with other configurations such as steering current [START_REF] Sweeney | A nerve cuff technique for selective excitation of peripheral nerve trunk regions[END_REF]. However, this study showed the need of powerful programmable waveform multioplar stimulator such as the one described in [START_REF] Andreu | A distributed architecture for activating the peripheral nervous system[END_REF] to complete experimental assessment. Owing to this technology, we aim at designing experimental setup to validate these preliminary simulation results.

Fig. 1 .Fig. 2 .

 12 Fig. 1. Cross section of nerve model with 333 fibers. Electrode contacts are represented by their position around the nerve (0 • to 270 • ). Minimal and maximal target areas are represented

Fig. 3 .

 3 Fig. 3. Activation threshold for each configuration and each diameter. Conf 1: one pulse of TT configuration with 300µs duration. Conf 2: 4 prepulses of TT configuration and a stimulating pulse of TT configuration. Conf 3: 4 prepulses of LTR configuration and one stimulating pulse of TT configuration. Color scale corresponds to thresholds of activation from -1 mA and -3 mA excepted for Conf 1 -1 mA and -1.7 mA.

Fig. 4 .

 4 Fig. 4. Mean selectivity index for each configuration, and various target size. For each target, SI is optimal for fibers with 10µm diameter.

French National Institute for computer science and applied mathematics (INRIA), University of Montpellier, CAMIN team, Montpellier, FRANCE.surname.name@inria.fr

VI. ACKNOWLEDGEMENTS

This work was supported by a grant from BPIFrance, "Intense", #6354


Sandra Martínez
email: sandra.martinez@globope.es

Miguel Mediavilla
email: miguel.mediavilla@globope.es

Jenny Bäckstrand
email: jenny.backstrand@jth.hj.se

Carolina Bernardos

Alignment of the purchasing strategy to the business strategy: an empirical study on a harbour cranes company

Keywords: Purchasing function, purchasing strategy, category management, business strategy

The purchasing function is assuming an increasingly relevant role within companies in the last decades. This is due to a fact that purchasing strategy can contribute to develop competitive advantages. Therefore, it is important to align the purchasing strategy with the company business strategy. On the other hand, category management can be used as the basic unit of strategic purchasing analysis, which measures the competitive improvement in purchasing management. It its known that a differentiated purchasing strategy involves managing suppliers within the different categories, so that, it is considered that there should be a leadership to level category by purchasing managers to improve the company competitiveness. Hence, this paper contributes by presenting how aligned business and purchasing strategies and product categorization leads to increased competitiveness -by presenting an empirical study on a harbor cranes company.

Introduction

In the past few decades the purchasing function has changed from a passive administrative role into a strategic function [START_REF] Ellram | Strategic purchasing: a history and review of the literature[END_REF][START_REF] Van Weele | Purchasing and supply chain management: Analysis, strategy, planning and practice[END_REF][START_REF] Alinaghian | Proposing a model for purchasing system transformation[END_REF][START_REF] Monczka | Purchasing and supply chain management[END_REF] having direct responsibility for the costs of goods purchased (e.g. materials, products or services), as well as supplier management. This change has increased the impact and influence of the purchasing function to achieve competitive advantages for the business, as other business functions do. Moreover, this development is logical, as the sourced components represent a large and growing percentage of the total cost of a product, as well as these components have a crucial importance depending on its quality and performance [START_REF] Errasti | Gestión de compras en la empresa[END_REF].

The purchasing strategy is the process of planning, implementing, evaluating and controlling the strategic and operative purchasing decisions. These decisions lead all activities of the purchasing function toward opportunities that are consistent with the capabilities of the company in order to achieve the long-term objectives [START_REF] Carr | An empirically based operational definition of strategic purchasing[END_REF]. Hence, in order to get competitive advantages, the purchasing strategy must be aligned with the overall strategy of the company. Furthermore, different purchasing strategies are needed for different types of purchased items [START_REF] Kraljic | Purchasing must become supply management[END_REF][START_REF] Marketing | Category management -Positioning your organization to win[END_REF].

The literature shows that in this era of purchasing it is necessary to provide solutions to different challenges, risks and characteristics. Neverthelessone of the most important challenges is to align the purchasing strategy with the business strategy, . In order to achieve a better alignment, one key step is to define the appropriate purchasing strategy for each purchasing category in order to achieve the goal defined within the business strategy [START_REF] Carr | An empirically based operational definition of strategic purchasing[END_REF], [START_REF] Lindblom | Suppliers' roles in category management: a study of supplier-retailer relationships in Finland and Sweden[END_REF][START_REF] Slack | Operations strategy[END_REF][START_REF] Carter | Is purchasing really strategic?[END_REF][START_REF] Bäckstrand | A Method for Customer-driven Purchasing -Aligning Supplier Interaction and Customer-driven Manufacturing[END_REF].

Therefore, the research question would be: How can the alignment of purchasing strategy with business strategy and product categorization improve the competitiveness of a company?

In order to give an answer this question, this paper will illustrate through an empirical study how aligned strategies lead to increased competitiveness. First, the paper presents a brief literature review; then the adopted research methodological approach is presented. Then, a case study carried out on a harbor cranes company is explained. Finally, the paper concludes by highlighting the contribution of the research.

2

Literature review

Strategic alignment

The purchasing function is assuming an increasingly relevant role within companies. This is due to a fact that purchasing strategy can contribute to get competitive advantages. Therefore, it is important to align the purchasing strategy with the business strategy of the company. Generally, business strategy is concerned with developing distinct competences and competitive advantages [START_REF] Andrews | The Concept of Strategy[END_REF]. One approach to business-level strategy is the competitive strategies, introduced by Porter [START_REF] Porter | Competitive Strategy: Techniques for Analyzing Industries and Competitors[END_REF], that drive an actor to compete as cost leader, differentiator, or a focused provider.

For manufacturing actors, the competitive business strategy is translated into competitive priorities and operationalized through functional strategies [START_REF] Ward | Competitive Priorities in Operations Management[END_REF][START_REF] Krause | Toward a measure of competitive priorities for purchasing[END_REF][START_REF] Kroes | Outsourcing congruence with competitive priorities: Impact on supply chain and firm performance[END_REF]. According to previous research, purchasing strategy also requires the identification of competitive priorities [START_REF] Krause | Toward a measure of competitive priorities for purchasing[END_REF], [START_REF] Watts | Linking purchasing to corporate competitive strategy[END_REF] in order to support business strategy. However, different purchasing strategies are needed for different types of purchased items. Additionally alternative ways of categorizing or classifying items and/or suppliers is necessary.

Necessities for a competitive purchasing strategy configuration are external resources, location, suppliers network design, purchasing organization (from process and functional perspectives) and standardization and improvement of the purchasing and procurement processes. Additionally the globalization necessarily affect the purchasing function, forcing it to be global too [START_REF] Martínez | Framework for configuring production and logistics networks of SMEs and SBUs within an internationalization process[END_REF]. Van Weele [START_REF] Van Weele | Purchasing and supply chain management: Analysis, strategy, planning and practice[END_REF] defined global purchasing as "the activity for searching and obtaining goods, services and other resources on a possible worldwide scale, to comply with the needs of the company and with a view to continuing and enhancing the current competitive position of the company". It includes all phases of the purchasing process, starting even before the definition of the specification list, through supplier selection and buying, up to the followup and evaluation phase. Moreover, purchasing management is one of the first steps to define and design a global supply chain [START_REF] Leenders | Purchasing and Supply Management[END_REF].

Category management

To define a category strategy it is advisable to have systematic classifications [START_REF] Lilliecreutz | Supplier classification as an enabler for a differentiated purchasing strategy[END_REF] to help defining and visualizing the different categories. One of the most commonly used tools for categorization was developed by Kraljic [START_REF] Kraljic | Purchasing must become supply management[END_REF], who proposed a matrix that classifies items into categories according to their profit impact and supply risk. This matrix has become the standard in models of purchasing categories [START_REF] Monczka | Purchasing and supply chain management[END_REF], [START_REF] Gelderman | Purchasing portfolio models: a critique and update[END_REF].

In the early 90s in the UK new principles of management throughout the supply chain was developed, the so called "Efficient Consumer Response" (ECR). Its best known process, Category Management (CM) [START_REF] Gruen | Determinants and outcomes of plan objectivity and implementation in category management relationships[END_REF][START_REF] Dewsnap | Category management: a new approach for fashion marketing?[END_REF], is defined as 'a process that involves managing product categories as business units and customizing them on a store-by-store basis to satisfy customer needs' [START_REF] Marketing | Category management -Positioning your organization to win[END_REF] and shifted the focus from brand management approach to a category management approach [START_REF] Dussart | Category management: Strengths, limits and developments[END_REF]. Later, CM was also adapted to categorize purchased items [START_REF] O'brien | Category Management in Purchasing: A strategic approach to maximize business profitability[END_REF].

According to Mediavilla et al. [START_REF] Mediavilla | Logística Sanitaria: Retos y Nuevas Tendencias, World-Class Hospital Logistics[END_REF] and Errasti [START_REF] Errasti | Gestión de compras en la empresa[END_REF], proper category management requires to:

1. Categorize items. 2. Set achievable goals within the business strategy. 3. Prioritize the purchasing categories. 4. Define strategic objectives of purchasing and consequently establish improvement projects and their deployment. These targets should be aligned with the business strategy. 5. Set management indicators for each project phases. 6. Ensure lasting results.

Therefore this CM can be used as the basic unit of strategic analysis, which measures the competitive improvement on purchasing management [START_REF] Monczka | Purchasing and supply chain management[END_REF], [START_REF] Gruen | Determinants and outcomes of plan objectivity and implementation in category management relationships[END_REF][START_REF] Dewsnap | Category management: a new approach for fashion marketing?[END_REF].

A differentiated purchasing strategy then involves managing the suppliers within the different categories. According to some authors [START_REF] Van Weele | Purchasing and supply chain management: Analysis, strategy, planning and practice[END_REF], [START_REF] Monczka | Purchasing and supply chain management[END_REF] it is considered that there should be a leadership by purchasing managers per category to improve the competitiveness of the company.

Research methodology

The research is based on a literature review and a case study following the constructive research methodology. Constructive research is an approach that aims to produce solutions to explicit problems and is closely related to the concept of innovative constructivism [START_REF] Meredith | Theory building through conceptual methods[END_REF]. This approach develops an innovative solution, which is theoretically grounded, to a relevant practical problem. An essential component of constructive research is the generation of new learning and knowledge in the process of constructing the solution [START_REF] Mendibil | Designing effective team-based performance measurement systems: an integrated approach[END_REF]. The case study as such is exploratory in nature. Two of the researchers have been actively involved in the project transition of the case company. Thus, facets of action research have also been deployed. In action research both researchers and clients are actively engaged in solving a client-initiated project dealing with a certain business problem [START_REF] Westbrook | Action Research: A new paradigm for research in production and operations management[END_REF][START_REF] Rowley | Using Case Studies in Research[END_REF][START_REF] Voss | Case Research in operations management[END_REF]. The company selected for the case faced the challenge of aligning its purchasing strategy to a recently changed business strategy, providing an interesting case for academics.

The main data collection and observation period lasted for 5 months during 2013 and consisted of meetings, interviews and company internal documentation. The researchers attended meetings once a week with the Purchasing Manager, CEO, Chief Engineer, Supply Chain Manager, Quality Manager and Sales Manager. The first phase of the case research included meetings and interviews that focused on understanding the harbor cranes industry and the company specific portfolio of products. During the second phase, researchers, together with Purchasing and Quality Manager, mapped the main processes within procurement function. . Finally, the third phase focused on developing and deploying new strategy of purchasing management based on Mediavilla et al. [START_REF] Marketing | Category management -Positioning your organization to win[END_REF] and Errasti [START_REF] Errasti | Gestión de compras en la empresa[END_REF].

Case research

The case company is a Spanish provider of integral solutions for container terminals, i.e that the company designs, manufactures, transports and erects container-handling cranes. Moreover, the case company has also its own software and hardware to optimize terminal management (terminal automation). The case company is the regional supplier for Europe, Mediterranean, North and South Atlantic side of the Americas and this company is part of an international corporation.

In order to develop and deploy a new purchasing strategy, to the first step was to push a proper category management by: 1. Splitting the products on purchasing categories. 2. Defining the main contribution of each given purchasing category to the business strategy (E.g. competitive advantage on costs or lead-time). This is the so-called purchasing strategy per category. [START_REF] Errasti | Gestión de compras en la empresa[END_REF][8] 3. Prioritization of levers per category, seeking levers which could reinforce the given competitive advantage 4. Deployment of purchasing strategies per category by applying the selected levers. The prioritization could be based on the potential competitive improvements (E.g. saving or qualitative impact) and implementation effort. 5. 6. Establishment management indicators: potential cost savings per crane. 7. Control system to review achieved results and strategy coherence along the time. The following is an example of how the category management was carried out for a specific purchasing category in the case company.

1. The analyzed product was divided on in 42 purchasing categories. However, in this case research the focus will be on one category, called 'mechanical elements' which is composed by products such as sheaves. This category could be manufactured by a large number of suppliers, which decreases the possible supply risk but will not optimize the cost if the company is not able to create the appropriate competition. Moreover, this category has a medium profit impact. Therefore, according Kraljic's matrix [START_REF] Kraljic | Purchasing must become supply management[END_REF] this category is a leverage item (see Figure 1). Purchasing strategies for all portfolio quadrants, based on Kraljic's matrix [START_REF] Kraljic | Purchasing must become supply management[END_REF], [START_REF] Gelderman | Handling measurement issues and strategic directions in Kraljic's purchasing portfolio model[END_REF] 2. The main contribution to the business strategy that the category "mechanical elements" has is to improve the purchasing cost (i.e. the purchasing strategy is to reduce costs on this category). Therefore, the selected levers (i.e. how to achieve the purchasing strategy) were to introduce new suppliers and to standardize the components. Taking into account the risk/challenges and purchasing power matrix (figure 2) [START_REF] Errasti | Gestión de compras en la empresa[END_REF][START_REF] Gelderman | Handling measurement issues and strategic directions in Kraljic's purchasing portfolio model[END_REF], The recommended purchasing policy is to exploit purchasing power by increasing the competition between different suppliers, pushing the purchasing strategy of reducing costs. Likewise, it is also suggested to establish supplier relation case by case in order to exploit the purchasing power [START_REF] Errasti | Gestión de compras en la empresa[END_REF] (see Figure 2). 3. The analyzed category, according to the prioritization, belongs to the first wave of implementation according to Errasti [START_REF] Errasti | Gestión de compras en la empresa[END_REF], meaning that the ease of implementation is medium or high and the potential savings are medium or high too (see Figure 3). 4. The target was to have three new suppliers and to eliminate the current supplier due to quality problems and non-compliance with delivery dates. The company executed supplier scouting actively. 5. As a result of the strategy implementation, the supplier basis was changed and a cost reduction of approx. 50% was achieved. That situation is totally aligned to the purchasing strategy as well as to the contribution that the category made to the business strategy. 6. Currently, the company continues working to strengthen relations and establish long-term agreements with the new suppliers.

Result

Two of the three suppliers were located in a low cost country and the third one was located in Spain. The Spanish supplier was a supplier totally oriented to short delivery times and for unexpected situations.

Contribution

The case research shows that the use of the category management (i.e. to categorize items in purchasing categories, set purchasing strategic objectives, prioritize the purchasing categories according to the potential savings and implementation difficulties, define and deploy improvement projects, set management indicators and ensure lasting results) and the alignment of the purchasing strategy with business strategy allow to improve company competitiveness.

Fig. 1 .

 1 Fig. 1.Purchasing strategies for all portfolio quadrants, based on Kraljic's matrix[START_REF] Kraljic | Purchasing must become supply management[END_REF],[START_REF] Gelderman | Handling measurement issues and strategic directions in Kraljic's purchasing portfolio model[END_REF]

Fig. 2 .

 2 Fig.2. Risk/challenges and power relation matrix, based on Errasti[START_REF] Errasti | Gestión de compras en la empresa[END_REF]

Fig. 3 .

 3 Fig. 3. Potential savings and implementation difficulties for different purchasing categories, based on Errasti [5]