Primavera De Filippi

THE CONCEPT OF A DIGITAL COPY

Keywords: Internet, Copyright law, digital technologies, ontologies, legal concepts

Copyright law has been challenged by the advent of digital technologies. It is today necessary to draw a distinction between the concept of a "copy" according to whether it refers to a physical copy (token) or a digital copy (type). While, in the physical world, the copy determines the scope of the copyright license, in the digital world, it is the copyright license that actually determines the scope of a digital copy.

Introduction

The advent of Internet and digital technologies has radically transformed the way information is being regulated on the Internet. While digital media provide new opportunities for authors to produce and disseminate their works to the public, they simultaneously encourage and facilitate copyright infringement. Traditionally, in order to ensure compliance with the law, the copyright regime could rely upon the properties of physical media to constitute a natural barrier against copyright infringement. As the medium went digital, however, its properties became a catalyst for infringement.

Designed for the physical world, the structure of the copyright regime does not adequately address the issues inherent to digital media. Indeed, although the notion of a "copy" is central to copyright law, the concept has not been precisely defined within the law. The law must recognize that physical copies fundamentally differ from their digital counterparts. Once a work has been incorporated into a physical medium, the content becomes part of the medium and cannot be easily extracted or modified without causing damage. In the digital world, instead, the work is made of digital bits that can be perfectly transferred from one medium to another without any quality lossso that the property of being a copy is only a temporary feature of the physical medium.

If the identity of a digital copy can no longer be defined by its physical characteristics, it becomes thus necessary to define the copy of a digital work according to a different set of criteria. The claim is that, while a physical copy has always been regarded as a token that is capable of only one instantiation, a digital copy should instead be regarded as a type that is capable of multiple instantiations. The question is then, how do we define this type? This paper suggests that if, in the physical word, the copy determines the scope of the copyright license under which it has been released, in the digital world, it is the copyright license that actually determines the scope of the copy to which it refers. This means that the copyright owner can actually decide the scope of a digital copy by either increasing or reducing the level of restrictions incorporated into the

Ontological Analysis of Copyright Works

The Functional Requirements for Bibliographic Records (FRBR) is a simple ontological model whose objective is to assist users in the identification and retrieval of information. Developed by the International Federation of Library Associations and Institutions (IFLA), the FRBR is a conceptual model for the description and identification of bibliographic records.1 The framework of the FRBR is however flexible enough that it can be used to identify the various components of a work that constitute the object of copyright law. It is composed of four basic entities:

• the "work" represents the underlying structure and ideas of the work (e.g. Hamlet by Shakespeare). As a general concept, it must be distinguished from both the physical medium through which it is conveyed to the public and the actual content thereof, since the same work can be articulated in many different ways and incorporated into an indefinite number of media. • the "expression" articulating the work represents the actual content of that work (e.g. the sequence of words from a particular edition of Hamlet). It only refers to the conceptual arrangement of signs and symbols that constitute the work but is not concerned with the way in which the content has been incorporated into a particular medium of expression. • the "manifestation" represents the format by which the expression has been recorded into a medium (e.g. the typographical arrangement of a published edition). It refers to both the format assumed by a particular expression (e.g. the size and colour) and the physical characteristics of the medium into which it has been incorporated (e.g. paper-back versus hard-cover books). • the "item" represents the physical medium that incorporate one particular manifestation (e.g. a particular copy of the book). It identifies a concrete physical object that exhibits a consistent set of attributes over time. Indeed, as opposed to the three other aspects of the work, the item is a token (as opposed to a type) that can only exist as a single instance.

The situation has become even more complex with the advent of digital technologies. Given that the physical characteristics of a digital work are likely to change over time, the item can no longer be used to identify the copy of a work in the digital environment, where the transfer of a digital file from one device to another would necessarily generate a new item. A different set of criteria must therefore be taken into account to determine the scope of a digital copy.

Physical Media versus Digital Media

The particularity of digital media, as opposed to physical media, is that they are not bound to the content they convey. A book, for instance, incorporates a literary work, which cannot be removed from the medium without actually damaging the book. The content of the literary work also cannot be modified, revised or updated, without considerably affecting the integrity of the medium. Using the terminology of the FRBR framework, we can say that the item is inherently connected to the manifestation it incorporates. Upon creation, the item assumes the characteristics of one particular manifestation (type). That type will remain an inherent property of the item until the latter is destroyed or significantly damaged.

The situation is much different for digital media, whose nature is inherently dynamic. Digital media merely incorporates a series of digital bits that can be changed and reorganised to represent an indefinite number of works. Digital media introduce thus an additional layer of analysis, which subsists between the physical item (e.g. a hard drive or a cd-rom) and the content it conveys (e.g. a melody by J.S. Bach). This layer consists of the sequence of bits (0's and 1's) incorporated into the physical device. Borrowing from the terminology of the FRBR framework, this sequence can be defined as the digital manifestation of a work, which describes the way in which the expression has been recorded into a medium.

As opposed to the manifestation, which depends both on the way the content has been formatted and the medium into which it has been incorporated, the digital manifestation no longer accounts for the characteristics of the medium into which a work is recorded. 2 The reason for this is twofold.

On the one hand, the content is no longer bound to one particular medium given that the same content can travel from one medium to the other without incurring any change in its format or any quality loss. On the other hand, the medium is no longer bound to the content it conveys given that the sequences of bits incorporated into the medium can be changed at any moment in time. The item, as defined within the FRBR framework, is thus no longer connected to only one work or manifestation.

To illustrate the idea, let us take the example of music. In the earlier days, music was mechanically incorporated into the surface of a disc (e.g. a vinyl disc) by means of a series of grooves representing the sound waves to be played. 3 Once it has been created, the surface of a disc cannot be modified to incorporate a different sound. As the medium is forever tied together with the content it has been assigned with, it is fair to assume that every disc constitutes a copy of the work it incorporates. Few years later, magnetic tapes were introduced, allowing for sound to be recorded as a magnetic pattern onto the tape. The content of a tape can therefore evolve over time, as a variety of sounds can be recorded onto the same tape by merely changing the magnetic properties thereof.

As opposed to the previous technology, magnetic tapes are no longer bound to one particular piece of content. Yet, given the deterioration of the magnetic coating, their content can only be updated a limited number of times before they would become unusable. 4 This problem has been resolved with the advent of the Compact Disc, which marked the shift from the analogue to the digital world.

Content is first converted into digital bits and then stored on an optical disc as a series of small indentations. 5 Because the content is digital, it can be indefinitely written and re-written without any quality loss.

Medium Content Extraction

Vinyl Disc

Specific to 1 type of content: sound waves are encoded as a series of grooves recorded mechanically on the disc.

Content is permanent: cannot be tampered with without ruining the media.

Extraction is not possible if not by analogue means.

Magnetic Tape

Specific to 1 type of content: sound waves are encoded as a magnetic pattern.

Content is changeable: tapes can be magnetized but risk of deterioration.

Extraction is not possible if not by analogue means. As opposed to analogue media, whose content can be recorded and reproduced only through a specific process that is different for each medium (e.g. scratches on a disc, magnetic pattern on a tape, patterns of ink on a book), the process of digitization creates an intermediary entity (the digital manifestation) that subsists independently of the medium it has been recorded into. In the digital world, there is no direct correlation between the physical medium and the type of work it incorporates. An image, a sound wave, a video, or even a literary work can all be converted into a sequence of bits to be subsequently embodied into a digital device. Given the digital nature of these works, their content can be easily extracted and re-incorporated into different mediums without any quality loss and without any risk of deterioration.

Compact Disc

Digital technologies thus marked the complete separation between the medium and the content, which is only momentarily stored into a digital device. As long as the medium is capable of storing digital bits, a digital work can be transferred from one medium to the other without incurring any changes to its format. Regardless of whether it has been stored on a hard disk, a jump drive, or a cdrom, the digital manifestation will always remain the same.6 In contrast to physical media, who are specific to one particular type of content, digital media can be regarded as a "generic medium" which incorporates anything that can be converted into 0's and 1's. Indeed, most digital media are nowadays acquired without any information within. Hard-drives, memory sticks, but also cd-roms are often sold in a blank state, to be subsequently filled up by users with content of different types.

Most of the content stored into a digital medium is variable. Works are transferred from one device to another on a daily basis and for a variety of purposes. Users constantly update their digital devices with new content, while older content is deleted or moved into a backup drive. The consequence is that the content of digital media is inherently dynamic. In the digital environment, it thus no longer makes sense to regard the physical medium as a "copy" of the work it incorporates, since the quality of being a copy is only a temporary attribute of the medium. A different entity must be identified in order to describe the copy of a digital work.

Physical Copies versus Digital Copies

For the purposes of copyright law, the notion of a "copy" is a concept whose function is to identify the instance of a work consistently over time. While the item might be the best candidate to qualify as the copy of a physical work, with the advent of digital technologies, the distinctive characteristics of a copy have been considerably affected. Without going into unnecessary technical details, it can be said that a physical copy differs from a digital copy in at least three ways.

Firstly, a physical copy is such that the content it incorporates contributes to shaping its identity as a thing. The vinyl disc featuring a song from Elvis Presley is different from the vinyl disc featuring a melody by J. S. Bach -which necessarily displays an entirely different set of bumps and grooves on its surface. Similarly, despite their ability to be overwritten, magnetic and compact discs are often defined by their content. The cd incorporating a recording of Elvis is considered to be of a different "type" from the one incorporating a performance by Bach. Even if the content of the former could be overwritten with the content from the latter, this operation would most likely have an impact on the perceived identity of the medium, which would be regarded as a new copy by the majority of people.7 Nowadays, however, the identity of digital media does no longer depend upon the content it incorporates.8 A 250gb hard-drive is considered to be of the same "type" as any other 250gb hard-drive, regardless of the content stored therein. Likewise, the identity of a usb-stick will remain the same over time, even if its content has changed. In the eyes of most users, the medium is therefore only a temporary carrier of information.

Secondly, a physical copy always preserves its identity whenever it is transferred from one place to the other. When a physical medium is moved, the content is carried along with the medium without incurring any change in terms of its physical characteristics, except for its location in space. When a digital file is transferred from one digital device to the other, the physical characteristics of the medium incorporating the file can be very different from each other. Even if the sequence of bits is likely to remain the same, bits can be expressed in a variety of ways according to the device on which they are stored (e.g. the same sequence of bits will be encoded differently on a cd-rom, than on a hard drive or a usb key). Hence, if the copy of a work were defined by its physical characteristics, the mere fact of transferring one file from one device to another would necessarily create a new copy of the work. This can be problematic because, even though the transfer will produce a new instance of the work (i.e. the same sequence of bits incorporated into a different medium), for all practical purposes, both instances will be regarded by virtually everyone as the same copy of the work.9

This leads to the third fundamental difference that subsists between a physical copy and a digital copy. While, in the physical world, there can be only one entity that qualifies as the copy of a work, in the digital environment, more than one entity could be regarded as the same copy of the work. A different meaning should therefore be assigned to the concept of a "copy" according to whether it refers to a physical or to a digital work. While the former qualifies as a "token" that is capable of only one instantiation, the latter is commonly seen as a "type" that is capable of multiple instantiations. This is not to say, however, that every instance of a digital file incorporating a work will necessarily qualify as the same copy of the work. While two separate copies of the book Hamlet would undeniably be regarded as two different copies of the same book, two digital files incorporating the same recording of Elvis could also be regarded, under a specific set of circumstances, as two different copies of the same recording. Indeed, if the scope of a digital copy were as broad as the scope of a digital file, it would mean that, in the digital environment, a copy ultimately refers to the manifestation of a work. While this is obviously too broad in most cases (e.g. it would no longer be possible to differentiate between different instances of the same digital file), it might actually be too narrow in some other respects. For instance, the mere fact of compressing a digital file would necessarily generate a new manifestation, which would no longer qualify as the same copy, even though it would be logically regarded as such. The same would apply for encryption, and to some extent, for the conversion from one digital format to another. Hence, while it is no longer possible to rely on the physical characteristics of a copy in order to determine its identity in the digital environment, it is also not possible to rely only on its digital characteristics (the digital manifestation). Another set of criteria must therefore be identified.

Scope of Digital Copies

If we look at the provisions of copyright law, we can see that the copyright regime does not assign the same meaning to a physical copy and a digital copy. This is especially obvious in the context of the exhaustion of rights, where a distinction is clearly made between the two. 10 Yet, the law does not provide any explanation on why are digital copies different from physical copies, nor does it provide any guidance on how to determine the scope of a digital copy. a general rule, a specific connection can be observed between the scope of a copyright licence and the scope of the copy to which it refers. This is especially apparent in the physical world, where the physical boundaries of the copy determine the scope of the licence regulating the manner in which that copy can be used and/or accessed. In the digital world, however, since the copy no longer has any physical boundaries, it becomes difficult to determine the scope of the copyright licence. In order to preserve the connection that subsists between the scope of the copy and the scope of the copyright licence under which it has been released, in the digital environment, it might be necessary to look at the terms and conditions of the copyright licence so as to define the scope of the digital copy to which the licence refers.

While, in the digital environment, end-user licensing agreements have become much more restrictive than they were in the physical world, 11 this additional set of restrictions might nonetheless be justified on a variety of grounds. Indeed, in the physical world, a large number of 10 The WIPO Copyright Treaty expressly states that: "the copies subject to the right of distribution refer exclusively to fixed copies that can be put into circulation as tangible objects". This statement has been re-iterated within the preamble of the InfoSoc Directive, and within the DCMA report on Section 104, which both draw a distinction between the distribution of physical and digital copies. 11 When purchasing the copy of a work, ownership is transferred only to the medium in which the work is embodied (e.g. a CD-ROM). While the work is itself is owned by the copyright owner, a license is granted to the user allowing for a certain usage thereof. In the digital environment, however, copyright licenses hove become increasingly restrictive and are often offered on a take-it-or-leave-it basis, so that users have no way to negotiate the terms and conditions of the license and are sometimes not even fully aware of them. See e.g. LINDSAY, D. ( 2002 restrictions are automatically imposed upon users by virtue of the physical characteristics of the copy, rather than by means of contractual provisions. Those are for the most part restrictions related to the reproduction, alteration and dissemination of copies, which cannot be done without incurring considerable costs or efforts. These restrictions need not be incorporated into the contract because they are automatically enforced by the natural laws of the world we live in. 12 In the digital world, most of these restrictions are gone, as the reproduction, the alteration and the dissemination of digital works can be done instantaneously and at minimal costs. 13 It becomes thus necessary to insert them explicitly into the contractual agreement. While this might not be the main justification for most of the restrictions incorporated into many end-user licensing agreements, this is nonetheless a relevant factor to be taken into account. Given that one needs no longer abide to the rules of the physical world in order to determine the scope of a copy, the digital environment provides additional flexibility in deciding the actual scope of one copy. By means of contractual agreements, copyright owners are entitled to decide exactly what can or cannot be done with any digital copy, whose reproduction and dissemination can be either allowed or forbidden under a variety of conditions.

In this respect, it is interesting to distinguish between two categories of restrictions: the formal criteria, which refer to the conditions that must be satisfied by the copy in terms of digital format and manifestation; and the legal criteria, which refer to the conditions of usage that must be fulfilled by the user who has acquired a licence to that copy. Finally, an additional element to be accounted for is the user, or the category of users to which the license is addressed. This can be either very broad, as in the case of most public licences such as Creative Commons, 15 very narrow, as in the case of many individual licensing agreements addressed to only one user. In-between are the large variety of licences addressed to one category of users (e.g. students, in general or from a particular university, employees, members of a particular institution or association, or even just family members). combining those three elements together, it becomes possible to describe the scope of a digital copy according to the way it has been defined by the copyright owner. As opposed to the physical world, where the scope of the copyright license is determined by the physical boundaries of the copy, in the digital world, it is the copyright licence that determines the boundaries of the digital copy to which it refers. The digital copy is therefore a type whose scope ultimately depends on the provisions of the copyright license under which it has been released. As such, it can be For instance, it is generally difficult to reproduce a vinyl disc without acquiring the appropriate machines (which are expensive enough to require the establishment of large economies of scale before the initial investment can be effectively recouped). Likewise, it is virtually impossible to modify the content of a vinyl disc and it is relatively costly and time consuming to transfer it from one place to another. 13 Internet and digital technologies have given the possibility for anyone to reproduce, modify and/or redistribute copies of any digital work on a worldwide scale, in virtually no time, and at very low costs. The properties allowing for the self-enforcement of the copyright regime within the physical world are therefore lacking in the digital environment, where copyright infringement is no longer subject to any kind of technological barrier. For more details on the impact of the digital technologies on the enforceability of copyright law, see e.g. HALPERN, S. W. (2001) The Digital Threat to the Normative Role of Copyright Law. Ohio State Law Journal, 62. 14 For instance, users might be allowed to change the format of a work (e.g. by converting it from MP3 format to OGG format), but only at the condition that every digital rights management information is preserved. Similarly, users might be allowed reproduce a digital work into either an identical format (e.g. the duplication of a PDF file) or a different format (e.g. the printing of a PDF file into paper), although reproduction might be restricted for a limited number of times and distribution be constrained to a limited category of users. Additional limitations might also be introduced with regard to the different types of usages that can be made of a copy (e.g. how it can be accessed, when it can be used, and whether it can transferred from one device to the other). 15 A public license does not identify nor impose any limit on who may qualify as a potential licensee but merely grants the license to the general public. See e.g. Creative Commons at http://creativecommons.org/licenses.

simultaneously incorporated into multiple instances that will all qualify as the same copy of the work by reason of the similarity in their formal and legal characteristics.

One important thing to note is the distinction between "internal reproduction" -i.e. the production of a new instance of the same copy, and "external reproduction" -i.e. the production of a new copy. The former is an operation that necessarily remains within the scope of the same copy. It does not, therefore, trigger the exclusive right of reproduction, given that copyright law is only concerned with the making of additional copies of a work, rather than with the making of additional instances of the same copy. The latter constitutes instead actual reproduction, which might actually violate the exclusive right of reproduction granted under the law. Whether or not this reproduction can be regarded as a legitimate one fundamentally depends on whether it has been allowed within the licensing agreement (e.g. if the contract allows for the making of additional copies of the work) or whether it would fall within the realm of fair uses (e.g. personal or private copies). 16

Changing the Rules without Changing the Law

The concept of a "copy" is a social construct that does not correspond to anything in reality. 17 As such, its meaning may change according to the context of analysis. the purpose of a copy in copyright law is to identify the various instances of a work, it must necessarily account for the distinctive characteristics of the work. A copy might therefore be assigned a different meaning according to whether it refers to a physical or a digital work.

ontological analysis of copyright works through the FRBR framework demonstrated that, in the physical world, the item is the entity that best represents the copy of a work. The same is not true in the digital world, where the item has become unable to identify the copy of a work consistently over time. While it has always been regarded as a token, the advent of digital technologies might thus require the definition of a copy to be revised.

In this paper, it is suggested that the word "copy" should be assigned two different but correlated meanings. One meaning can be used to denote the multiple instances of a work that subsist in the physical world (copy as a token), whereas the latter can be used to denote the digital copy of a work as a general class of entities that cannot be precisely quantified in the physical world (copy as a type). 18 That way, the law will assume a different meaning according to the context of analysis: in the physical world, the standard meaning of "copy" will apply, whereas, in the digital world, the 16 The verbatim reproduction of a digital file (e.g. in the case of back-up copies) will therefore always qualify as an internal reproduction as long as that the resulting digital file will always satisfy the requirements of the copyright license. However, although this reproduction is not as such concerned by the copyright regime, the user might nonetheless violate the provisions of copyright law to the extent that the file is transferred to someone who is outside of the scope of the copyright license. 17 One fundamental problem with the identification of the copy of a work is that a "copy" is a concept that does not exist in nature. It is the result of a social construction based upon a common and shared understanding of what society has intended to be a copy. For more details on the distinction between real objects and intentional objects, see e.g. INGARDEN, R. & GRABOWICZ, G. G. (1979) The Literary Work of Art: An Investigation of the Borderlines of Ontology, Logic, and Theory of Language, Northwestern University Press. 18 In order to better understand the difference that subsists between a physical copy and a digital copy, it might be useful to rely upon a linguistic artifact that is characteristic of the English language. In ordinary language, it is common practice to refer to a particular entity differently according to the level of details that needs to be taken into account.

For instance, as opposed to mass nouns (e.g. money, water, bread, etc) whose quantity cannot be assessed if not by referring to a particular portion thereof (e.g. a liter of water, a portion of bread, etc), count nouns refer instead to individual entities that can be separately counted and evaluated (e.g. coins, water drops, grains, etc). Certain words can however be employed both as count nouns and as mass nouns according to the context of analysis -e.g. 'Fire burns' vs. 'There is a fire in the forest'. In the context of copyright law, the word "copy" could therefore be understood as a count noun -in the case of physical copies, or as a mass noun -in the case of digital copies.

word "copy" will assume a much broader meaning that is likely to encompass multiple instances of a work.

The main advantage of this approach is that it makes it possible to change the default rule of copyright law in the digital environment, without actually changing the wording of the law. Indeed, by merely changing the way in which a word is defined, or the way in which it should be construed, it becomes possible to increase or decrease the default level of protection granted under the law.

If the first step was to acknowledge the difference between a physical copy and a digital copy, the next step is to provide a definition of the term "copy" that is more consistent with the context of analysis. Although physical copies have been defined by the law,19 the definition of digital copies has yet to be provided.

According to this paper, a digital copy is a type that is capable of multiple instantiations, and whose scope ultimately depends upon the terms and conditions of the copyright license under which it has been released.

Given the broader scope of a digital copy, some activities that would qualify as copyright infringement in the physical world might actually be legitimate in the digital world. Most important in this respect is the question of reproduction, which is no longer a good indicator of copyright infringement in the digital environment. If the reproduction of a work without the consent of the author is generally forbidden in the physical world (unless it falls within one of the copyright exemptions or fair use), the same should not be true in the digital environment where the mere use or transfer of a work necessarily requires the reproduction thereof. By default, therefore, reproduction of a digital file should be legitimate as long as the digital manifestation remains the same. 20 Other activities such as compression, encryption or conversion are also often required for accessing a digital work, using it, storing it, or even just transferring it onto another device with a different file system. By default, these standard operations should thus also be allowed in the digital environment, since preventing them would run counter to the standard expectations of users. 21 Under this approach, anyone would be entitled to produce and use several instances of a work provided that they all qualify as the same copy. Whether the reproduction of a digital file qualifies as a new copy of the work for the purpose of copyright law will depend, on the one hand, on the interpretation that is given to the concept of a copy, and, on the other hand, on the terms and conditions of the copyright license. If the new instance is compatible with the formal and legal requirements of the copyright license, it will qualify as a new instance of the same copy, otherwise, it will qualify as a new copy -whose legitimacy will depend upon the context in which it has been and by the user or the category of users to which it has been assigned.

While this might not actually affect the content of many end-user licensing agreements, the advantage of this approach is that it is likely to be more compatible with the current praxis and user expectations that have emerged with the advent of Internet and digital technologies. 22 This approach is also more compatible with the concept of sharing that has been emerging over the past years, in particular with the advent of Open Source and Creative Commons licences. 23 Defining the scope of a digital copy according to the contractual provisions of the copyright license under which it has been released would allow anyone belonging to the same category of users to share their digital copies internally within the group, provided that the copyright license does not differentiate between one user or the other. This is even more relevant in the case of digital works published on the Internet without any specific licence. In this no license would apply, but since no group has been defined, the addressee of the copy would be the public at large. The copy can therefore be freely reproduced and disseminated over the Internet and only illegitimate usages would actually bring an action for copyright infringement. The free reproduction and distribution of digital works would thereby become the default in the digital environment, while nonetheless preserving the possibility for right holders to increase the level of protection by means of contracts or technology.

Conclusion

Recognizing the differences between physical and digital copies is key to understanding that the law should not treat them in the same way. A rule that is sensible in the physical world might actually seem unreasonable in the digital world. In order to restore the traditional balance of copyright law in the digital world and to better comply with the specificities of digital media, different rules should apply in the digital environment. If a physical work is different from a digital work, the two should not be regulated according to the same rules.

Yet, given the global scope of the Internet network, reforming copyright law to the digital environment might be a very complicated task that would require changing the law of a very large number of countries. Instead of trying to change laws, the proposition of this paper is that it might be easier to change the perception of those who interpret the law.

Indeed, adapting the provisions of copyright law to the digital environment might only require changing the way in which the word "copy" is construed. Rather than deriving the meaning of the word by analysing the provision of the law (the inferential approach), this paper suggests an ontological approach to actually modify the provisions of copyright law by merely changing the meaning assumed by the word.

idea is to change the default rule of copyright law in the digital environment, by assigning a different definition to the concept of a copy, according to whether it subsists to the physical or to the digital environment. When referring to physical copies, the word "copy" should be regarded as token that describes the physical item into which a work has been incorporated. When referring to digital copies, the word should instead be regarded as a mass noun that could be used to denote an indefinite number of instances, which qualify as the same copy of the work by virtue of the fact that they all comply with the provisions of the copyright license under which the work has been released.

holders are actually unhappy with this trend, much of the content published on the Internet is nowadays produced by users who do not really benefit from such a high level of protection. For a more detailed analysis, see BENKLER, Y. (2006) The Wealth of Networks: How Social Production Transforms Markets and Freedom, Yale University Press. 23 The advent of the digital technologies has led to the emergence of a strong set of ideals, which advocate the free circulation of knowledge and the sharing of culture as a common, in line with the principles of the "gift economy" (see CHEAL, D. (1998) The Gift Economy, Routledge. as well as CASTELLS, M. ( 2001) The Internet galaxy: Reflections on the Internet, business and society, Oxford University Press. introducing the concept of the gift economy to describe the mechanisms of Open Source).

The advantage of this approach is that it does not require any legislative reforms, but could merely be implemented by judges, by precedents, or through a series of guidelines on interpretation coming from an international body or organisation.

  ) The law and economics of copyright, contract and mass market licenses, Australia, Centre for Copyright Studies. BURKE, J. J. A. (2003) Reinventing Contract. Murdoch University Electronic Journal of Law, 10.

Table 1 : Comparing the characteristics of different media

 1

	Compatible	with	all	Content is temporary:	Extraction is possible:
	content: can store anything encoded in a sequence of digital bits.	can be readily replaced with no quality loss.	digital bits can be written and extracted indefinitely

The framework can be accessed at http://www.ifla.org/en/publications/functional-requirements-for-bibliographicrecords.

The physical characteristics of the medium are no longer relevant in the digital environment. All digital media are equivalent for the purposes of storage and transmission because: (1) The same digital work can be stored into any digital medium. Since the work has become intangible, it is not fixed to one particular medium and can thus freely travel from one medium to the other; (2) The same digital medium can be used to store any digital work. Once a work has been digitized, there is no difference between a literary work, a musical work or an audiovisual work, since they can all be represented by a series of 0's and 1's. See MUELLER, M. (1999) Digital Convergence and its Consequences. ThePublic, 6,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]

A record player (or gramophone) is an analog device invented in 1877 by Thomas Edison to reproduce sound mechanically recorded onto a disc. The sound is stored directly on the surface of a rotating cylinder or disc, as a series of grooves, bumps, or scratches, whose size is directly connected to the musical notes they store. As the disc rotates, a needle traces the wavy lines and vibrates, thereby reproducing the sound waves.

Magnetic tapes were invented in 1928 by Fritz Pfleumer as a way of recording analog audio signals as a magnetic pattern on a tape. From a blank state, tapes can be magnetized by applying electrical current that is proportional to the sound signal to be stored on the tape. The magnetic pattern can subsequently be read out by a specific device in order to reproduce the original signal. Although magnetic tapes can be magnetized several times, they nonetheless suffer from deterioration so that extensive usage can render the tape unusable.

The development of the Compact Disc in 1978 revolutionized the audio world by introducing digital technology for the first time. The Compact Disc is an optical disc used to store digital content as a series of tiny indentations (pits) applied onto the surface of the disc. The height of pits determines the way the light is reflected, so that the content can be read from the disc by the intensity change of the light.

In the physical environment, the manifestation is intrinsically related to the actual medium of expression (the physical item) in which a work has been embodied -e.g. the hard-cover edition of a literary work constitutes a different manifestation than the paper-back edition of the same work. In the digital realm, instead, given that it merely consists of a series of bits, the manifestation of a digital work does not depend upon the physical characteristics of the digital device into which the work has been stored. In the digital environment, the manifestation is no longer associated with any physical medium, but with the digital medium as a whole.

This is essentially due to the process required to modify the content of a cd, which involves the modification of the physical attributes of the medium that contribute to shaping its identity as a copy (i.e. altering the surface of the cd to change the way the light reflects).

Fort he majority of modern digital media, changing the content does no longer require any alteration of the physical attributes of the medium, but merely changing the magnetic polarity or the electric charge of the physical support.

The transfer of a digital file is achieved by generating a new file in another location and subsequently destroying the original. The two are likely to assume a different physical representation while nonetheless maintaining their distinctive properties as a copy. See PASKIN, N. (2003) On Making and Identifying a Copy. D-Lib Magazine, 9.

US Copyright Act s.101 "Copies" are material objects, other than phonorecords, in which a work is fixed by any method now known or later developed, and from which the work can be perceived, reproduced, or otherwise communicated, either directly or with the aid of a machine or device. The term "copies" includes the material object, other than a phonorecord, in which the work is first fixed.

As an internal reproduction, in fact, the verbatim reproduction of a digital work does not produce a new copy of the work but only a new instance of the same copy.

Therefore, while modifying the content of a work (the expression) will necessarily trigger the exclusive right of making derivative works, merely modifying the format of that work (the manifestation) will not as such constitute copyright infringement, unless it has been expressly forbidden by the law (e.g. in case it would qualify as the circumvention of a technological measure of protection) or by the provisions of the copyright licence.

In the digital environment, information is generally reproduced and disseminated over the network by a large number of users who do not actually care about whether or not this constitute a violation of copyright law. While many right


Dominik T Matt
email: dominik.matt@unibz.it

Prof T Dominik

Matt

Application of Axiomatic Design principles to control complexity dynamics in a mixed-model assembly system: a case analysis

Keywords: AXIOMATIC DESIGN, FLEXIBLE ASSEMBLY, MANUFACTURING COMPLEXITY THEORY, FUNCTIONAL PERIODICITY axiomatic design, flexible assembly, manufacturing systems, design of production systems, complexity theory, functional periodicity

HAL is

Introduction

Durable goods manufacturing has undergone almost constant change over the past two decades. Globalization of markets has driven this industry to leave the security of mass production in favor of lean and flexible manufacturing models. However, these concepts have already become state of the art in modern manufacturing system design. Their implementation is no longer a unique competitive advantage, but has become a vital prerequisite in global competition. Today's challenges for manufacturing go beyond these concepts. Since sales figures can hardly be forecasted, it is necessary to conceptualize not only flexible but highly adaptable systems which can be upgraded by more scale-economic solutions during product life cycle, even under extremely difficult forecasting conditions [START_REF] Spath | Mutability for a Profitable Assembly in Germany[END_REF]. Unlike flexible systems, changeable ones are expected to be capable of actively varying their own structure [START_REF] Nyhuis | Evaluation of Factory Transformability[END_REF]. Due to the unpredictability of change, they are not limited to a pre-defined system range typical for so called flexible systems but are required to shift between different levels of systems ranges (Zaeh et al. 2005). As modern manufacturing systems are increasingly required to be adaptable to changing market demands, their structural and operational complexity increases, with a negative impact on system performance [START_REF] Nyhuis | Wandlungsfähigkeit -ein systemischer Ansatz[END_REF]. However, literature review shows that although many authors have investigated complexity mechanisms and the related interactions between the production system and the surrounding market environment, no suitable frameworks or measures have been developed to track and control the dynamic evolving complexity of a manufacturing system in order to promote and facilitate its changeability. The qualitative understanding of complexity presented in this paper is based on Suh's (2005) Axiomatic Design (AD) based definition of complexity as the uncertainty of (sustainably) fulfilling a system's functional requirements. Like other important research works on complexity theory, it differentiates between two classes of complexity: the time-independent, structural or static complexity and the time-dependent, operational or dynamic complexity [START_REF] Frizelle | Measuring complexity as an aid to developing operational strategy[END_REF][START_REF] Calinescu | Complexity in manufacturing: an information theoretic approach[END_REF][START_REF] Blecker | Mass Customization vs. Complexity: A Gordian Knot?[END_REF], where time-independent complexity is associated with the variety embedded in the static system and time-dependent complexity is attributed to the uncertainty of the dynamic system.

The purpose of this paper is to investigate the mechanisms of dynamic complexity in terms of internal and/or external drivers and the impact on a flexible manufacturing system's performance. As a result, a framework for monitoring and controlling of dynamic complexity can be derived that helps to anticipate operational performance losses by a timely definition and implementation of measures for a focused system redesign. Therefore, this research work retraces a series of manufacturing system redesign initiatives in a medium-sized durable goods manufacturing company along a ten year time period that timely helped to maintain and improve the firm's manufacturing system's competitiveness in terms of time, cost and quality even in turbulent environmental conditions. The objective of the case analysis is to test the validity of Axiomatic Design (AD) based complexity theory as an explanatory construct and as a methodological guidance in order to develop a decision support system for the early detection of need for change in a flexible manufacturing system.

Since this is a perennial retrospective case study of continued manufacturing system redesign interventions "before" and "after" variations of the system will be examined.

The study has been motivated by a best practice example of a specific industrial case focused on a mixed-model assembly of durable goods but it encourages believing that the findings can be extended to other manufacturing systems and industries as well.

The paper is organized as follows. Section 2 reviews literature on manufacturing related complexity theory and on the application of Axiomatic Design principles in manufacturing system design. In Section 3, the research methodology is developed from the literature and the hypotheses are described. Section 4 illustrates and discuses the results of the case analysis. The concluding Section 5 discusses the implications of the research findings and further research work.

Literature review

This section starts with the review of the existing research work done in the field of manufacturing related complexity theory. It will explain the reasons why the AD based complexity theory seems to be most suitable to fulfil this paper's purpose. In a next step, the literature regarding the application of AD principles in the field of manufacturing systems will be reviewed.

Complexity theory

Complexity is difficult to define precisely. A general definition of complexity is that a complex system is one, which has a large number of elements, whose relationships are not simple [START_REF] Simon | The architecture of complexity[END_REF]. These variables, namely number, dissimilitude and states' variety of the system elements and relationships, allow differentiating between static and dynamic complexity. Whereas static complexity describes the system structure at a defined point in time, dynamic complexity represents the change of system configuration in the course of time [START_REF] Blecker | Mass Customization vs. Complexity: A Gordian Knot?[END_REF]. When both complexities are low, then the system is simple; when both complexities are high, then the system is said to be extremely complex (Ulrich and Probst, 1988).

Manufacturing's systems are complex. They have many elements with obvious, but non-simple relationships to each other. [START_REF] Frizelle | Measuring complexity as an aid to developing operational strategy[END_REF] argue that systems with higher complexity have more problems than systems with lower complexity, and that measuring manufacturing complexity provides a useful metric for improvement.

In order to understand how factors like product variety, changing quality requirements or varying customer demand regarding packaging or delivery service complicate manufacturing processes and in turn impact the performance of production systems, some research work has been conducted mainly in the investigation of the static manufacturing system complexity. [START_REF] Deshmukh | Complexity in manufacturing systems, part 1: Analysis of static complexity[END_REF] derived an information-theoretic entropy measure of complexity for a given combination and ratio of part types to be produced in a systems success in delivering the desired production capacity. In [START_REF] Hu | Product variety and manufacturing complexity in assembly systems and supply chains[END_REF] and [START_REF] Hu | Product variety and manufacturing complexity in assembly systems and supply chains[END_REF] the variety induced manufacturing complexity in manual mixedmodel assembly lines is considered where operators have to make choices for various assembly activities. The authors propose a complexity measure called "operator choice complexity" to quantify human performance in making choices.

Through three case studies, [START_REF] Frizelle | The measurement of complexity in production and other commercial systems[END_REF] proposed methods to quantify the system's immanent complexity while considering the data uncertainty that is due to measurement noises. [START_REF] Jenab | A graph-based model for manufacturing complexity[END_REF] presented a graph-based model to measure the relative manufacturing complexity and the manufacturing similarity of products in job shop manufacturing systems in order to support assembly and production cost estimation, and to provide a guideline for creating a product with the most effective balance of manufacturing and assembly.

Little research, however, has focused on how to describe manufacturing system performance in terms of whether it is capable to handle and control the market and product demand induced dynamic complexity. [START_REF] Sivadasan | An Information-Theoretic Methodology for Measuring the Operational Complexity of Supplier-Customer Systems[END_REF] developed an entropy-based methodology to measure the operational complexity of suppliercustomer systems associated with the uncertainty of material and information. Other research has recently explored new entropic-related complexity measures to describe the uncertainty induced by the rescheduling of the production [START_REF] Huaccho Huatuco | Comparing the impact of different rescheduling strategies on the entropicrelated complexity of manufacturing systems[END_REF]. However, these studies do not provide any guidance and mechanisms to install a continuous monitoring and controlling of a manufacturing systems dynamic complexity in order to maintain or even enhance its performance over time. Suh (2005) defined the complexity in the context of manufacturing system design "as the measure of uncertainty in achieving the FRs (functional requirements) due to a poor design or to the lack of understanding and knowledge about the system". The author introduces the Axiomatic Design (AD) based complexity theory as a comprehensive approach to describe the mechanisms of a manufacturing system's static and dynamic complexity and illustrates the concept of functional periodicity in a scheduling problem of a machine cluster to control the system's time-dependent combinatorial complexity. Apart from the described example of a scheduling problem which handles dynamic complexity only in a given tolerance range of a manufacturing system's flexibility, no research work has been done so far to use the AD approach in the context of an already flexible manufacturing system's (re)design to changeability.

Application of AD principles in manufacturing system design

The following papers are good examples of design of manufacturing systems based on Axiomatic Design principles [START_REF] Kulak | Applications of axiomatic design principles: A literature review[END_REF]. [START_REF] Suh | Manufacturing system design[END_REF] presented the first study using AD principles for a manufacturing system design based on the independence axiom. [START_REF] Cochran | The application of AD and lean management principles in the scope of production system segmentation[END_REF] proposed a method based on the principles of lean management and the independence axiom of axiomatic design principles which converted production system to small, flexible, and non-central production units to design a production system that could be managed more effectively. [START_REF] Kulak | A complete cellular manufacturing system design methodology based on axiomatic design principles[END_REF] presented an approach to transform traditional production system from process orientation to cellular orientation, based on axiomatic design principles. [START_REF] Houshmand | An extended model of design process of lean production systems bymeans of process variables[END_REF] proposed an axiomatic design modelling of lean production system design. [START_REF] Nakao | Decoupling executions in navigating manufacturing processes for shortening lead time and its implementation to an unmanned machine shop[END_REF] used the independence axiom in order to shorten the lead-time of tailor-made products by eliminating couplings. [START_REF] Matt | Template based Design of Lean Production Systems[END_REF] described a template approach based on the independence axiom to give guidance to manufacturing system designers in the fast and efficient design of lean and flexible manufacturing systems. Using only the independence axiom which describes the time-independent part of AD based complexity theory, none of the research works performed in the field of AD application in manufacturing system design considered the impact of system dynamics so far. Therefore, this research is motivated to develop a suitable methodological framework on the basis of the Axiomatic Design related complexity theory to track and control the dynamic evolving complexity of a flexible manufacturing system in order to promote and facilitate its changeability.

Research methodology

The methodology applied in this research has two main components: First, a theoretic framework for the explanation of a manufacturing system's dynamic complexity drivers and their control is developed basing on the principles of AD related complexity theory. Its practical relevance is then investigated on the basis of a longterm study carried out at a durable goods manufacturer, here onwards referred to as "the company".

Axiomatic Design based complexity theory

According to Suh (2005), most complexity theories deal with the complexity of a system in its physical domain which contains the design solutions or design parameters (DPs) to satisfy the functional requirements (FRs) that describe the design goals for the system. However, complexity problems can be difficultly solved in the physical domain, because every change of the elements and their relationships aiming at the reduction of the system's complexity might influence the overall system's behavior in an uncontrollable way due to the system designer's lack of understanding of the system's architecture. To provide a general theoretical framework for solving complexity problems in engineering and in production related areas, Suh (2005) defined complexity narrowly as a measure of uncertainty in achieving a set of design goals that a system must satisfy. Due to its time-dependency complexity must be measured in the functional domain: as technical and socio-economic conditions change over time, also the objectives and driving forces for manufacturing system design have changed. While in the early twentieth century labor productivity was the most important factor for measuring manufacturing performance, this objective started to change when automation began to play a dominant role and much more effort was dedicated to capital cost reduction. Currently, we are facing a general trend towards increasingly fluctuating market demand as consumers are asking for more individualized products and services. In the next future, probably shortages in raw material supply and increasing energy costs may drive the change in a manufacturing system's set of functional requirements. It can be noticed that the complexity of manufacturing systems depends on the functional requirements that are relevant at a given moment in history and thus their regular (re-)design is becoming one of the most important factors in determining industrial competitiveness (Suh 2005).

The underlying hypothesis of AD is that there exist fundamental principles that govern good design practice. The main components of AD are domains, hierarchies, and design axioms. The Axiomatic Design world consists of four domains: customer, functional, physical and process. Through an iterative process called zigzagging, the design process converts customer's needs (CNs) into Functional Requirements (FRs) and constraints (Cs), which in turn are embodied into Design Parameters (DPs). DPs determine the Process Variables (PVs). The decomposition process starts with the decomposition of the overall functional requirement -in practice this should correspond to the top system requirement.

Before decomposing to a lower level, the DPs must be determined for that level in the physical domain. Two basic axioms are distinguished [START_REF] Suh | Axiomatic design: Advance and applications[END_REF]: • Axiom 1 -Independence Axiom: Maintain the independence of the functional requirements. The Independence Axiom states that when there are two or more FRs, the design solution must be such that each one of the FRs can be satisfied without affecting the other FRs. • Axiom 2 -Information Axiom: Minimise the information content of the design. The Information Axiom is defined in terms of the probability of successfully achieving FRs.

3.1.1

The First Axiom: The Independence Axiom FRs and DPs are represented by vectors, their relationship by an n-dimensional matrix. For example, a 3-dimensional matrix the design equation can be written as follows: In terms of its elements, the above equation may be rewritten as follows:

          ⋅           =          
FR 1 = A 11 DP 1 + A 12 DP 2 + A 13 DP 3 FR 2 = A 21 DP 1 + A 22 DP 2 + A 23 DP 3 FR 3 = A 31 DP 1 + A 32 DP 2 + A 33 DP 3
In the special case of a one-to-one direct relationship between FRs and DPs, this matrix is reduced to a purely diagonal matrix which guarantees that every single DP just fulfils one FR. In an optimal system design, these elements are autonomous, they have no interrelations. Such a design is called an uncoupled design as the single equations can be solved independently. In any other case, the off-diagonal elements can be also represented by arrows. They show that the fulfilment of the diagonal element at the start of the arrow influences the elements at the end of the arrow. The worst case is a circular dependence. This is the case in a coupled design and it means a bad system design [START_REF] Lee | Understanding the value of eliminating an off-diagonal term in a design matrix[END_REF].

In the case of a triangular matrix circular dependence does not exist and therefore the design might be potentially good, although not optimal due to the given path dependency. This case is called a decoupled design. It is obvious that it is very difficult or sometimes quite impossible to really obtain an ideal design [START_REF] Suh | Axiomatic design: Advance and applications[END_REF].

The Second Axiom: The Information Axiom

The Information Axiom is the theoretic funding of the AD based complexity theory.

In the preceding section, the Independence Axiom was shortly introduced. The design process following the rule of the Independence Axiom may produce several acceptable design alternatives: uncoupled or decoupled. To determine, which of these represents the best solution, the Information Axiom can be applied.

"Insert Figure 1 about here"

As previously mentioned, the Information Axiom is defined in terms of the probability of successfully achieving FRs. The probability of success can be computed by determining the area of common range between the design range (dr) defined by the system designer to satisfy the FRs and the system range (sr) that the proposed design can really provide to satisfy the FRs within the specified range (Suh 2005). The larger this overlap, the lower the system's complexity (Figure 1). However, in a dynamic system like a manufacturing system, the complexity might increase over time as the system range moves out of the once specified design range.

Complexity theory based on Axiomatic Design

The complexity of any dynamic system is determined by the uncertainty in achieving the system's functional requirements and is caused by two factors (Suh 2005): by a time-independent poor design that causes a system-inherent low efficiency (system design), and by a time-dependent reduction of system performance due to system deterioration or to market or technology changes (system dynamics). The complexity that follows directly from the Information Axiom is the time-independent real complexity which tells whether the system range is inside or partly or completely outside the system's design range. To assure a manufacturing system's flexibility, a certain allowable tolerance regarding variations of the design range have to be defined. In the case of an ideal, uncoupled design, the allowable tolerance for DP i can be determined as follows (Suh 2005):

ii i i A FR DP ∆ = ∆
Consider now the decoupled design below: In the case of that 2-dimensional triangular (decoupled) matrix, the allowable tolerances for the DPs can be expressed as (Suh 2005):

          ⋅           =          
11 1 1 A FR DP ∆ = ∆ 22 1 21 2 2 A DP A FR DP ∆ - ∆ = ∆ 33 2 32 1 31 3 3 A DP A DP A FR DP ∆ - ∆ - ∆ = ∆
The total time-independent complexity contains also a second component for those design solutions that are not completely uncoupled: The so called time-independent imaginary complexity results from a lack of understanding of the system design. As it is not of direct relevance for this research, it won't be detailed further. When the system range moves as a function of time, then this is time-dependent complexity at work. There are two types of time-dependent complexity (Suh 2005): The so called periodic complexity exists only in a finite time period, resulting from a limited number of probable combinations. These probable combinations may be partially predicted on the basis of existing experiences with the system or with a very proportionally to the time-dependent increasing number of possible combinations of the system's functional requirements. Leaving the pre-defined flexibility tolerance, it may lead to a chaotic state or even to a system failure. The critical issue with combinatorial complexity is that it is completely unpredictable. Becoming able to control the combinatorial complexity means to obtain not only a flexible but a really changeable manufacturing system.

"Insert Figure 2 about here"

To control combinatorial complexity, a functional periodicity has to be introduced. First, a set of FRs that repeats cyclically must be identified. Among these, those FRs and their related DPs have to be identified that may be subject of a combinatorial process. To introduce functional periodicity, the selected set of FRs has to be reinitialized at a defined (periodically turning) point in time t 2 (Figure 2). How this procedure works in practice will be explained within the case study.

Case study

The main research question of this paper is: To what extent can Axiomatic Design based complexity theory help illuminate the regular redesign of a manufacturing system to improve its robustness regarding various changes driven by a timedependent combinatorial complexity that go beyond system flexibility and impact the system's efficiency in terms of time, quality and costs?

The research question is addressed by presenting a case study. Case studies are typically used for deeply investigating dynamic, experiential and complex processes and areas taking place in a fast-changing and fluid environment (Gilmore and Carson strength of case studies is that the necessary data can be collected over a long time period. Consequently, the researcher can go much further than a cross-sectional snapshot of a process [START_REF] Johnston | Theory testing using case studies in business-to-business research[END_REF][START_REF] Stuart | Effective case research in operations management: A process perspective[END_REF][START_REF] Ghauri | Designing and conducting case studies in international business research[END_REF].

The empirical basis of this paper is a single case study involving the production plant of a medium-sized Italian producer of durable goods. The case analysis refers to a long-term period of ten years starting from the year 2000. It aimed at identifying and analyzing the factors influencing the operational performance of manufacturing over an extended timeframe. Three main sources of data were used: a) semi-structured interviews with staff at the company, b) direct observations on the shop floor, and c) collection of documents and historical data from electronic databases/spreadsheets and documents such as production schedules, expected deliveries and actual deliveries records, and the related development of product variety.

Results

The results of the long-term study will be shown and discussed in the following section.

Identification of the FR-DP-set

The processes affected by system redesign were those related to company internal value stream from the procurement of materials and components to shipping, focusing however on the two sequential processes of (1) the mixed-model assembly and (2) packing process connected to each other by a decoupling buffer line. In terms of the long-term analysis subject to this research, the company's management emphasized two aspects for redesign. First, they aimed to maintain or even improve operational performance in terms of labor productivity with the constraints of an increased number of product types and variants. Second, flexibility had to be increased in terms of responsiveness to short-term customer requirements and volume changes, maintaining however a minimum of 95% delivery capacity.

Within the analyzed manufacturing system "assembly process -buffer linepacking process", the following FR can be derived from defined redesign objectives:

• FR 1 : Produce to demand at best achievable operational efficiency

The design parameters mapped by the functional requirements are:

• DP 1 : Design of flexible assembly (or packing) operations focused on customer demand pace and value added work

As this represents a one-FR-design, the Independence Axiom is always satisfied at this level. To bring the design task onto an implementable level, the design has to be further decomposed:

• FR 11 : Produce to the customer demand • FR 12 : Ensure flexibility to accommodate capacity increments at lowest cost • FR 13 : Ensure flexibility to accommodate future products and variants

For the case study's system, the corresponding DPs were stated as follows:

• DP 11 : Takt-time calculation based on real average customer demand • DP 12 : Multiple single-station mixed-model assembly and packaging cells designed to focus on value added work; number of assembly and packing stations are determined on the basis of their average cycle time and the required customer takt-time • DP 13 : Movable and reconfigurable stations to enable new cell redesign

The design equation and matrix is: According to the Information Axiom, in the next step the design will be analyzed regarding its information content. In this case study, set-up times and time for planned stand stills can be neglected. Thus, for the fulfillment of FR 11 , in DP 11 the takt-time can be determined according to the following simplified formula:

          ⋅           =          
Q H S A P T ap takt ⋅ ⋅ ⋅ =
with Q = daily average customer demand, P ap = yield of good units produced by the system, A = average availability of the manufacturing process, S = number of shifts per day (shifts/day), H = hours/shift. Any variation to demand represented by ∆Q has a direct impact on ∆DP 11 . It can be compensated by ∆H or by extra shifts. However, in our case example extra shifts are not a solution to be considered and thus the equation can be written with S=1 as follows (see also section 2.1.3), with A 111 = T takt /(P ap ⋅A): According to Italian labor legislation, a maximum of 2 hours of overtime per person and day are allowable and a maximum of 60 hours of overtime per person and year can be shifted for overtime compensation from one to the next year, with a reduced overtime premium of +10% in case of disbursement. However, as demand variation in this case study follows a normal distribution with a standard deviation that allows the achievement of a 95% delivery capacity within overtime flexibility, these constraints do not need to be considered. Furthermore, an average value of P ap ⋅A = 0.95 can be assumed in this case study.

For the fulfillment of FR 12 , in DP 12 the number of necessary stations K will be determined according to the following formula:

       Ζ ∉ +       Ζ ∈ = takt c takt c takt c takt c T T if T T T T if T T K 1
As already outlined in section 3.1.3, the allowable tolerance for DP 12 may be written as follows, with A 121 = A 122 = T c :

11 122 12 122 11 121 12 12 DP A FR A DP A FR DP ∆ - ∆ = ∆ - ∆ = ∆ with ( ) c ap max T P A H K K A FR ⋅ ⋅ ⋅ - = ∆ 122 12
In the above term, |∆DP 11 | represents the "tolerance" of the system -in this specific case in terms of overtime flexibility -which enables the system to balance "normal" variations in demand within a certain delivery capacity limit. However, as overtime is expensive and thus impacts FR 12 , it is suitable only for short term leveling of capacity peaks. A variation in demand can be managed only to a certain point by this type of flexibility. As soon as average demand starts to move, ∆DP 12 decreases.

For ∆DP 12 > 0, no action is needed (green zone). When ∆DP 12 moves towards 0 or starts to turn negative, then system re-design must be triggered (yellow zone). Latest for ∆DP 12 = -|∆DP 11 |, re-design has to start (red zone).

Investigation of the case study system's long-term behavior

The following Figure 3 and Figure 4 show the behavior of the manufacturing system in the investigated case study. In 2001, the new manufacturing system based on manual mixed-model assembly stations connected to the packing station(s) by a buffer line (see Figure 4) was introduced. Since then, the overall production system consists of several so called "assembly-buffer-packing segments" (short: assembly segment), each assigned to always one product family offering a high adaptability to variations in models and variants within the assigned product family; in this case study, we focus on just one of these assembly segments, called "segment C". Adaptability to demand volumes is guaranteed by the activation of further assembly stations along the buffer line.

Furthermore, the single assembly stations are also designed for fast and easy reconfiguration. This design perfectly fits with the above explained functional requirements and offers a very high volume, variant and redesign flexibility.

"Insert Figure 4 about here"

The observed assembly segment C started in 2001 with the activation of 7 assembly stations and 1 packing station, fulfilling the average daily demand of 600 units per day (Figure 3). The system was designed to allow a maximum of 10 stations to be allocated along the buffer line. The review of historical data shows that in a total of 9 stations were activated in one time. Moreover, the increase in variants and in demand at the same time caused the packing station to move out of the original design range so that a second station had to be added. Due to the introduction of several new products and variants, in 2007 demand and product mix had so much increased that the activation of the 10 th station would not have been sufficient. Furthermore, the two packing stations had already reached their capacity limit. Space requirements would not allow allocating 4 packing stations at the end of one assembly segment. Thus, production management decided to split the segment in two separate ones with 2 packing stations at the end of each buffer line (Figure 4). In the meantime, even this latest measure has reached its limits and since 2009, the system is subject to substantial redesign, similar to the one in 2001. This redesign includes also DP 13 ; however, no results can be reported so far as this latest initiative has not been concluded yet.

"Insert Figure 5 about here"

As previously outlined, a good way to control combinatorial complexity is to introduce a functional periodicity. First, a set of FRs that repeats cyclically must be identified. As assembly stations are de-coupled from packing stations by a buffer line, two separate sets of FRs must be defined according to the one presented in section 4.1, one for assembly and one for packaging. In this paper, focus is given just to the assembly part; however, procedure for packaging is similar. All FRs and their related DPs are subject to a combinatorial process. To introduce functional periodicity, the selected set of FRs has to be reinitialized at a defined (periodically turning) point in time. The investigation of the case study system's long-term behavior shows a cyclic behavior of redesign activities: with intervals of about 2 years, redesign was necessary. Figure 5 shows the company's functional periodicity in parallel to an economic cyclic behavior. In future, the FR-set of the investigated company can be regularly reinitialized by a programmed two-year trigger (see also Figure 2).

Presumably, there is a correlation between economic cycles and the company specific functional periodicity: the anticipation of economic trends could be -for examplerealized by introducing more cycles with shorter periods. However, prove for this assumption is still missing.

Conclusions

An AD based methodology to monitor and control the time-dependent complexity of manufacturing systems has been developed and illustrated on the basis of a single case study. The use of the AD based complexity mechanisms to investigate the characteristics of manufacturing systems especially regarding their time-dependent behaviour is novel both in its methodology and in the application field. The proposed analysis provides powerful insights on the dynamics of operational complexity and hence provides guidance to organisations in managing manufacturing system redesign more effectively. A key benefit of this measure is identifying complexity hotspots and trigger points to start system re-initialization. Concepts arising from this method are that of internal organisational ability to absorb operational complexity. The validation of the complexity methodology has been conducted through practical application and through confirmed results from a single industrial study carried out at an Italian producer of durable goods. The case study demonstrated that the methodology provides valid and valuable means of identifying and prioritising areas of high operational complexity. The methodology presented in this paper will continue to be developed and validated in further case studies. Areas of further work include: • The more detailed investigation of correlations between economic and market cycles and their impact on a company specific functional periodicity.

  manufacturing system.[START_REF] Elmaraghy | Manufacturing systems configuration complexity[END_REF] proposed a code-based structural complexity index to capture the amount of information in the manufacturing systems as well as another complexity measure to represent the probability of a manufacturing

  possible failure sources. The second type of time-dependent complexity is called combinatorial complexity. It increases as a function of time

  [START_REF] Ghauri | Designing and conducting case studies in international business research[END_REF][START_REF] Perren | Case-study method in small business and entrepreneurial research[END_REF][START_REF] Halinen | Using case methods in the study of contemporary business networks[END_REF]. Another

  a decoupled design and thus satisfies the Independence Axiom. For the purpose of this research work, no further decomposition will be needed at that stage.

  2003/2004 volumes would have justified the activation of an eighth station. However, first redesign was done in 2005 after having noticed that demand fulfillment with overtime and stand-by workers where neither sufficient nor very cost-efficient. Thus,

Figure 1 .

 1 Figure1. The area of common range A cr measures a system's time-independent real complexity. It might decrease due to the system's time-dependency(Suh 2005).

Figure 2 .

 2 Figure 2. The manufacturing system (re-)design process and its relation with functional periodicity.

Figure 3 .

 3 Figure3. The initial setup of the manufacturing system foresaw an increase in demand of up to 40%. In 2005, delivery could be maintained only with regular overtime.

Figure 4 .Figure 1 .Figure 2 .Figure 3 .Figure 4 .Figure 5 .

 412345 Figure 4. In 2007, two main factors were driving the need for change above the planned system-inherent flexibility: increase in demand volume and in product variety

•

  The generalization of the case study's findings and the respective evaluation in other case studies • A more detailed decomposition of FR-DP-relations to derive algorithms for the installation of early detection mechanisms Work in these areas is under development in collaboration with industrial partners. Suh, N. P., 2005. Complexity -theory and applications. Oxford University Press. Ulrich, H., Probst, G., 1988. Anleitung zum ganzheitlichen Denken und Handeln, Bern: Paul Haupt Verlag. Zaeh, M., Moeller, N., Vogl, W., 2005. Symbiosis of Changeable and Virtual Production. In: Zaeh et al. (eds), 1st International Conference on Changeable, Agile, Reconfigurable and Virtual Production (CARV 2005), Munich 22.09.-23.09.2005, Munich: Utz 2005, 3-10. Zhu, X., S. J. Hu, Y. Koren, S. P. Marin. 2008. Modeling of manufacturing complexity in mixed-model assembly lines. Journal of Manufacturing Science and Engineering 130 (5), 051013-10.

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