O. Isaksson - Academia.edu (original) (raw)
Papers by O. Isaksson
The manufacturing industry is going through a transition from developing of products to the provi... more The manufacturing industry is going through a transition from developing of products to the provision of product-service systems (PSS). Earlier research has identified different types of PSS offers in this product-service transition, from product offers that include services as “add-on”, to the sale of services that include tangible goods as “add-on”. This paper addresses what consequences this has on manufacturing organizations undergoing product-service transition. The purpose of the paper is to clarify key success factors for organizational changes needed in the transition process of developing different types of PSS offers. The results are based on the ongoing case study of a manufacturer in the aerospace domain; the analysis approached organizational transformation from organizational theory perspective. The study identified four key areas that need to be considered in the organizational transformation to PSS development: Business strategy and decision-making, Internal organiza...
Value is an appealing concept to elaborate a concise, over-arching cross-system requirements spec... more Value is an appealing concept to elaborate a concise, over-arching cross-system requirements specification to support the preliminary design phase of an aerospace development project. The paper aims to address the lack of intuitive visualisation means for communicating 'value'during preliminary design tasks by proposing an approach that uses colour-coded 3D CAD models. The methodological and technological enablers for value visualisation have been tested in design sessions with undergraduate students, showing ...
Proc of TMCE, 2008
The main aim of this paper is to present a methodology developed within the European Project VIVA... more The main aim of this paper is to present a methodology developed within the European Project VIVACE to guide the design and implementation of a Knowledge Enabled Engineering (KEE) system in a Virtual Enterprise. The proposed methodology tries to overcome some of the limitations which characterise traditional methods for Target Cascading, promoting a more collaborative and iterative approach to derive system specifications (in terms of advanced knowledge functionalities) from initial high-level ...
UK distance education university. Her background is mathematics and Philosophy. She has an MSC in... more UK distance education university. Her background is mathematics and Philosophy. She has an MSC in Applied Artificial Intelligence from the University of Aberdeen and a PhD in design from the Open University. She spent nearly ten years in Cambridge in the engineering design before returning to the Open University. She carries out empirical studies of design processes in engineering, construction and fashion; and researches on understanding and supporting designers in industry. She also works on theoretical concepts underlying design practise. She has published over 250 papers in reviewed journal and conferences. She is a member of the board of management of the Design Society and a co-chair of the Design Process Special Interest Group of the Design Society.
Proceedings of the Design Society: DESIGN Conference
Platform design has been firmly established in the automotive industry as a strategy to provide w... more Platform design has been firmly established in the automotive industry as a strategy to provide wider product variety while maintaining cost effective production. But this strategy can struggle to keep up with the pace and nature of emerging technologies. This paper reviews the existing approaches to modelling product platforms, and showcases the challenges at OEMs introducing new technological innovations in their platforms. A gap is identified in the methods to assess the ability of existing platforms to integrate new technologies whenever they become available.
Proceedings of the Design Society: DESIGN Conference
Function and constraints modelling are implemented to design two gridded ion thrusters for additi... more Function and constraints modelling are implemented to design two gridded ion thrusters for additive manufacturing (AM). One concept takes advantage of AM design freedom, disregarding AM limitations and is not feasible. The other concept considers AM limitations and is manufacturable and feasible. Constraints modelling highlights AM capabilities that can be improved, showing where future investment is needed. Constraints representation can also support the creation of technology development roadmaps able to identify areas of AM technologies that must be improved.
The Philosopher's Stone for Sustainability, 2013
The move towards offering Product-Service Systems (PSS) requires the involvement of stakeholders ... more The move towards offering Product-Service Systems (PSS) requires the involvement of stakeholders from different companies, possessing knowledge about the different product lifecycle phases. This setting poses unique challenges for traditional product manufacturers, which need to rearrange transaction-based relationships into long-term relationships of co-development. Knowledge sharing across organizational boundaries is, therefore, considered as a key enabler for the development of profitable PSS. The paper is based on a social network tie perspective, and its purpose is to describe and exemplify knowledge-sharing network for PSS development-in order to describe the impact of the shift toward PSS development on companies' relationships and responsibilities. Based on the findings from two research projects involving various partners from the aerospace industry, the paper concludes that the development of profitable PSS relies on the development of strong and weak ties across the supply network. Finally, a five stages model of the evolution of tie strength is proposed for classifying relationships within the PSS knowledge-sharing network.
The Philosopher's Stone for Sustainability, 2013
Procedia Computer Science, 2015
Instead of developing each new product from scratch, firms strive to reuse prior components and t... more Instead of developing each new product from scratch, firms strive to reuse prior components and technologies in new applications in order to improve robustness, reduce cost and shorten time-to-market. Technologies come in the forms of methods, designs and processes, and are suitable for reuse since they are concepts for solving certain problems that multiple products have use for. However, reuse of technology where the application context is different requires adaptation of both the technology and the product system into which it is introduced. In practice, the magnitude and sources for this effect are often underestimated, which leads to unanticipated uncertainty in product development projects with consequences for robustness and efficiency in development. Based on available literature and needs identified within a case company, this paper proposes a method for identifying potential challenges of technology reuse that may otherwise be overlooked or only implicitly acknowledged. The method features a scorecard that guides a workshop to be attended by technology experts and managers where the prospect for successful technology reuse is assessed.
Volume 7: 2nd Biennial International Conference on Dynamics for Design; 26th International Conference on Design Theory and Methodology, 2014
Design processes are subject to many uncertainties. Changes resulting from the need to respond to... more Design processes are subject to many uncertainties. Changes resulting from the need to respond to external uncertainties are one of the main drivers of engineering change and therefore for iteration in design processes. Another important cause of iteration in design processes arises from the dependencies in design information which is being generated as part of the design process itself. At the beginning of the design process engineers need to make an informed guess about the values of parameters that they need and can achieve. These values are passed on to others, who base their decisions on them. Design decisions are distributed and iterative among design teams, customers and suppliers. Communicated parameter values are uncertain in two different but related ways. First, there is the confidence, precision and commitment that the designers have in the values they specify. Second there are uncertainties in the values that can be achieved with the technology the new design employs. These issues become particularly challenging when they span design teams, customers and suppliers as they iterate to converge on a mutually effective solution. This paper looks at this type of convergent iteration through an example from the aerospace industry, which illustrates how uncertainty in operating temperature at the beginning of the design process requires a thorough understanding of the temperature ranges that solution alternatives, at different degrees of maturity, can operate under. This paper argues that the key to managing convergent iterations lies in communicating the available ranges of parameter values and in understanding how design margins have arisen in existing technologies. These margins on product parameters provide potential performance which exceeds immediate functional requirements. The paper develops and formalizes the concept of design margins and argues that margins are included into products for a variety of reasons that are not always transparent to different team members. Analysis of margins enables design companies to reason in terms of ranges of values describing the scope for design change in meeting customer and supplier requirements without being forced into unplanned iteration loops.
IFIP Advances in Information and Communication Technology, 2013
Engineering change is ubiquitous throughout the product lifecycle to meet new requirements or dea... more Engineering change is ubiquitous throughout the product lifecycle to meet new requirements or deal with emerging problems in the product.. Components have a certain capacity to buffer the impact of changes before they pass changes on to other components. These buffers are margins on the components which exceed the current requirements. Typically these margins are designed into a product at the beginning and eroded in the course of the design process or during future upgrades. Fundamental design decisions are being taken based on an understanding of the margins available when considering design alternatives. This paper argues that the knowledge and understanding of these margins is the key to managing engineering changes through the product lifecycle. By tracking key product margins a company can assess when an engineering change could lead to costly knock-on effects.
Engineering change is ubiquitous throughout the product lifecycle to meet new requirements or dea... more Engineering change is ubiquitous throughout the product lifecycle to meet new requirements or deal with emerging problems in the product.. Components have a certain capacity to buffer the impact of changes before they pass changes on to other components. These buffers are margins on the components which exceed the current requirements. Typically these margins are designed into a product at the beginning and eroded in the course of the design process or during future upgrades. Fundamental design decisions are being taken based on an understanding of the margins available when considering design alternatives. This paper argues that the knowledge and understanding of these margins is the key to managing engineering changes through the product lifecycle. By tracking key product margins a company can assess when an engineering change could lead to costly knock-on effects.
Volume 7: Structures and Dynamics, Parts A and B, 2012
ABSTRACT This paper presents a preliminary design optimization study of a jet engine structure us... more ABSTRACT This paper presents a preliminary design optimization study of a jet engine structure using a knowledge-based master modeling approach. The objective function is derived based on input-output relationships of a cost-performance model, where specific fuel consumption, pressure loss and direct cost are considered. The advantage of this problem formulation is that it entails a single composite objective function that takes into account mass, structural characteristics, dynamic response and translates them to a direct operational cost function to be minimized. A fan-blade-off scenario is considered as the loading case in this paper. The loss of one fan blade during nominal operation causes a rotor imbalance and structural deformation.
Concurrent Engineering, 1998
In the design of high temperature components, design evaluation often requires an iterative proce... more In the design of high temperature components, design evaluation often requires an iterative procedure between thermal fluid and thermal structural simulations An integrated computer system providing an iterative environment for the multidisciplinary simulations re quired has been developed. The system supports iterations between thermal fluid and thermal structural simulations using two different commercial simulation packages. Traditionally, fluid and structural analysis have been simulated separately and analysis of coupled prob lems has required special, multidisciplinary simulation packages which are seldom used in early stages of design. Improving the infrastruc ture for data exchange between separate computer applications is one way to significantly reduce the lead time for design iterations. This reduction in lead-time allows multidisciplinary effects to be accounted for in early stages of design. The design system is demonstrated on an exhaust manifold, where the thermal int...
The success of engineering companies is highly dependent on how well product information is manag... more The success of engineering companies is highly dependent on how well product information is managed, engineered and communicated. From marketing through development to after sales activities, data ...
The Philosopher's Stone for Sustainability, 2013
The move towards offering Product-Service Systems (PSS) requires the involvement of stakeholders ... more The move towards offering Product-Service Systems (PSS) requires the involvement of stakeholders from different companies, possessing knowledge about the different product lifecycle phases. This setting poses unique challenges for traditional product manufacturers, which need to rearrange transaction-based relationships into long-term relationships of co-development. Knowledge sharing across organizational boundaries is, therefore, considered as a key enabler for the development of profitable PSS. The paper is based on ...
The Philosopher's Stone for Sustainability, 2013
Total Offers, Functional Products, and Integrated Product Service Engineering reflect a shift tow... more Total Offers, Functional Products, and Integrated Product Service Engineering reflect a shift toward service offers from manufacturing industry captured within the term Product-Service Systems (PSS). Manufacturing companies have traditionally focused design and development activities on realizing technical and engineered aspects of physical artifacts, while PSS include deeper understanding of customers' expectation, needs and perceived value, hence calling for modelling of additional aspects. The change in early design ...
The main aim of this paper is to present a methodology developed within the European Project VIVA... more The main aim of this paper is to present a methodology developed within the European Project VIVACE to guide the design and implementation of a Knowledge Enabled Engineering (KEE) system in a Virtual Enterprise. The proposed methodology tries to overcome some of the limitations which characterise traditional methods for Target Cascading, promoting a more collaborative and iterative approach to derive system specifications (in terms of advanced knowledge functionalities) from initial high-level targets. Social and behavioural aspects of Knowledge Management play a crucial role when many different users, knowledge experts, and process owners are involved in the Knowledge Management System (KMS) development. A well designed methodology is needed, therefore, to enhance communication and information sharing among design teams, to promote requirements merging and to take care both of the technological and behavioural aspects of the implementation. Initial business targets have been step-by-step decomposed into a set of sub-problems (Service Requirements, Knowledge Issues, and Knowledge Challenges) in the form of simple sentences in natural language. Then Quality Function Deployment (QFD) matrixes have been used to identify the set of functionalities to be implemented in the system, addressing the most important knowledge-related problems outlined in the cascading activity.
Design Science
As products are being developed over time and across organisations, the risk for unintended accum... more As products are being developed over time and across organisations, the risk for unintended accumulation and mis-conception of margins allocated may occur. Accumulation of margins can result in over design, but also add risk due to under allocation. This paper describes the different terminology used in one organisation and shows the different roles margins play across the design process and in particular the how margins are a critical but often overlooked aspect of product platform design. The research was conducted in close collaboration with a truck manufacturer between 2013 and 2018. The objective was to gain understanding of the current use of margins, and associated concepts evolve along the product life cycle, across organisation and product platform representations. It was found that margins already play an important role throughout the entire design process; however, it is not recognised as a unified concept which is clearly communicated and tracked throughout the design pr...
The manufacturing industry is going through a transition from developing of products to the provi... more The manufacturing industry is going through a transition from developing of products to the provision of product-service systems (PSS). Earlier research has identified different types of PSS offers in this product-service transition, from product offers that include services as “add-on”, to the sale of services that include tangible goods as “add-on”. This paper addresses what consequences this has on manufacturing organizations undergoing product-service transition. The purpose of the paper is to clarify key success factors for organizational changes needed in the transition process of developing different types of PSS offers. The results are based on the ongoing case study of a manufacturer in the aerospace domain; the analysis approached organizational transformation from organizational theory perspective. The study identified four key areas that need to be considered in the organizational transformation to PSS development: Business strategy and decision-making, Internal organiza...
Value is an appealing concept to elaborate a concise, over-arching cross-system requirements spec... more Value is an appealing concept to elaborate a concise, over-arching cross-system requirements specification to support the preliminary design phase of an aerospace development project. The paper aims to address the lack of intuitive visualisation means for communicating 'value'during preliminary design tasks by proposing an approach that uses colour-coded 3D CAD models. The methodological and technological enablers for value visualisation have been tested in design sessions with undergraduate students, showing ...
Proc of TMCE, 2008
The main aim of this paper is to present a methodology developed within the European Project VIVA... more The main aim of this paper is to present a methodology developed within the European Project VIVACE to guide the design and implementation of a Knowledge Enabled Engineering (KEE) system in a Virtual Enterprise. The proposed methodology tries to overcome some of the limitations which characterise traditional methods for Target Cascading, promoting a more collaborative and iterative approach to derive system specifications (in terms of advanced knowledge functionalities) from initial high-level ...
UK distance education university. Her background is mathematics and Philosophy. She has an MSC in... more UK distance education university. Her background is mathematics and Philosophy. She has an MSC in Applied Artificial Intelligence from the University of Aberdeen and a PhD in design from the Open University. She spent nearly ten years in Cambridge in the engineering design before returning to the Open University. She carries out empirical studies of design processes in engineering, construction and fashion; and researches on understanding and supporting designers in industry. She also works on theoretical concepts underlying design practise. She has published over 250 papers in reviewed journal and conferences. She is a member of the board of management of the Design Society and a co-chair of the Design Process Special Interest Group of the Design Society.
Proceedings of the Design Society: DESIGN Conference
Platform design has been firmly established in the automotive industry as a strategy to provide w... more Platform design has been firmly established in the automotive industry as a strategy to provide wider product variety while maintaining cost effective production. But this strategy can struggle to keep up with the pace and nature of emerging technologies. This paper reviews the existing approaches to modelling product platforms, and showcases the challenges at OEMs introducing new technological innovations in their platforms. A gap is identified in the methods to assess the ability of existing platforms to integrate new technologies whenever they become available.
Proceedings of the Design Society: DESIGN Conference
Function and constraints modelling are implemented to design two gridded ion thrusters for additi... more Function and constraints modelling are implemented to design two gridded ion thrusters for additive manufacturing (AM). One concept takes advantage of AM design freedom, disregarding AM limitations and is not feasible. The other concept considers AM limitations and is manufacturable and feasible. Constraints modelling highlights AM capabilities that can be improved, showing where future investment is needed. Constraints representation can also support the creation of technology development roadmaps able to identify areas of AM technologies that must be improved.
The Philosopher's Stone for Sustainability, 2013
The move towards offering Product-Service Systems (PSS) requires the involvement of stakeholders ... more The move towards offering Product-Service Systems (PSS) requires the involvement of stakeholders from different companies, possessing knowledge about the different product lifecycle phases. This setting poses unique challenges for traditional product manufacturers, which need to rearrange transaction-based relationships into long-term relationships of co-development. Knowledge sharing across organizational boundaries is, therefore, considered as a key enabler for the development of profitable PSS. The paper is based on a social network tie perspective, and its purpose is to describe and exemplify knowledge-sharing network for PSS development-in order to describe the impact of the shift toward PSS development on companies' relationships and responsibilities. Based on the findings from two research projects involving various partners from the aerospace industry, the paper concludes that the development of profitable PSS relies on the development of strong and weak ties across the supply network. Finally, a five stages model of the evolution of tie strength is proposed for classifying relationships within the PSS knowledge-sharing network.
The Philosopher's Stone for Sustainability, 2013
Procedia Computer Science, 2015
Instead of developing each new product from scratch, firms strive to reuse prior components and t... more Instead of developing each new product from scratch, firms strive to reuse prior components and technologies in new applications in order to improve robustness, reduce cost and shorten time-to-market. Technologies come in the forms of methods, designs and processes, and are suitable for reuse since they are concepts for solving certain problems that multiple products have use for. However, reuse of technology where the application context is different requires adaptation of both the technology and the product system into which it is introduced. In practice, the magnitude and sources for this effect are often underestimated, which leads to unanticipated uncertainty in product development projects with consequences for robustness and efficiency in development. Based on available literature and needs identified within a case company, this paper proposes a method for identifying potential challenges of technology reuse that may otherwise be overlooked or only implicitly acknowledged. The method features a scorecard that guides a workshop to be attended by technology experts and managers where the prospect for successful technology reuse is assessed.
Volume 7: 2nd Biennial International Conference on Dynamics for Design; 26th International Conference on Design Theory and Methodology, 2014
Design processes are subject to many uncertainties. Changes resulting from the need to respond to... more Design processes are subject to many uncertainties. Changes resulting from the need to respond to external uncertainties are one of the main drivers of engineering change and therefore for iteration in design processes. Another important cause of iteration in design processes arises from the dependencies in design information which is being generated as part of the design process itself. At the beginning of the design process engineers need to make an informed guess about the values of parameters that they need and can achieve. These values are passed on to others, who base their decisions on them. Design decisions are distributed and iterative among design teams, customers and suppliers. Communicated parameter values are uncertain in two different but related ways. First, there is the confidence, precision and commitment that the designers have in the values they specify. Second there are uncertainties in the values that can be achieved with the technology the new design employs. These issues become particularly challenging when they span design teams, customers and suppliers as they iterate to converge on a mutually effective solution. This paper looks at this type of convergent iteration through an example from the aerospace industry, which illustrates how uncertainty in operating temperature at the beginning of the design process requires a thorough understanding of the temperature ranges that solution alternatives, at different degrees of maturity, can operate under. This paper argues that the key to managing convergent iterations lies in communicating the available ranges of parameter values and in understanding how design margins have arisen in existing technologies. These margins on product parameters provide potential performance which exceeds immediate functional requirements. The paper develops and formalizes the concept of design margins and argues that margins are included into products for a variety of reasons that are not always transparent to different team members. Analysis of margins enables design companies to reason in terms of ranges of values describing the scope for design change in meeting customer and supplier requirements without being forced into unplanned iteration loops.
IFIP Advances in Information and Communication Technology, 2013
Engineering change is ubiquitous throughout the product lifecycle to meet new requirements or dea... more Engineering change is ubiquitous throughout the product lifecycle to meet new requirements or deal with emerging problems in the product.. Components have a certain capacity to buffer the impact of changes before they pass changes on to other components. These buffers are margins on the components which exceed the current requirements. Typically these margins are designed into a product at the beginning and eroded in the course of the design process or during future upgrades. Fundamental design decisions are being taken based on an understanding of the margins available when considering design alternatives. This paper argues that the knowledge and understanding of these margins is the key to managing engineering changes through the product lifecycle. By tracking key product margins a company can assess when an engineering change could lead to costly knock-on effects.
Engineering change is ubiquitous throughout the product lifecycle to meet new requirements or dea... more Engineering change is ubiquitous throughout the product lifecycle to meet new requirements or deal with emerging problems in the product.. Components have a certain capacity to buffer the impact of changes before they pass changes on to other components. These buffers are margins on the components which exceed the current requirements. Typically these margins are designed into a product at the beginning and eroded in the course of the design process or during future upgrades. Fundamental design decisions are being taken based on an understanding of the margins available when considering design alternatives. This paper argues that the knowledge and understanding of these margins is the key to managing engineering changes through the product lifecycle. By tracking key product margins a company can assess when an engineering change could lead to costly knock-on effects.
Volume 7: Structures and Dynamics, Parts A and B, 2012
ABSTRACT This paper presents a preliminary design optimization study of a jet engine structure us... more ABSTRACT This paper presents a preliminary design optimization study of a jet engine structure using a knowledge-based master modeling approach. The objective function is derived based on input-output relationships of a cost-performance model, where specific fuel consumption, pressure loss and direct cost are considered. The advantage of this problem formulation is that it entails a single composite objective function that takes into account mass, structural characteristics, dynamic response and translates them to a direct operational cost function to be minimized. A fan-blade-off scenario is considered as the loading case in this paper. The loss of one fan blade during nominal operation causes a rotor imbalance and structural deformation.
Concurrent Engineering, 1998
In the design of high temperature components, design evaluation often requires an iterative proce... more In the design of high temperature components, design evaluation often requires an iterative procedure between thermal fluid and thermal structural simulations An integrated computer system providing an iterative environment for the multidisciplinary simulations re quired has been developed. The system supports iterations between thermal fluid and thermal structural simulations using two different commercial simulation packages. Traditionally, fluid and structural analysis have been simulated separately and analysis of coupled prob lems has required special, multidisciplinary simulation packages which are seldom used in early stages of design. Improving the infrastruc ture for data exchange between separate computer applications is one way to significantly reduce the lead time for design iterations. This reduction in lead-time allows multidisciplinary effects to be accounted for in early stages of design. The design system is demonstrated on an exhaust manifold, where the thermal int...
The success of engineering companies is highly dependent on how well product information is manag... more The success of engineering companies is highly dependent on how well product information is managed, engineered and communicated. From marketing through development to after sales activities, data ...
The Philosopher's Stone for Sustainability, 2013
The move towards offering Product-Service Systems (PSS) requires the involvement of stakeholders ... more The move towards offering Product-Service Systems (PSS) requires the involvement of stakeholders from different companies, possessing knowledge about the different product lifecycle phases. This setting poses unique challenges for traditional product manufacturers, which need to rearrange transaction-based relationships into long-term relationships of co-development. Knowledge sharing across organizational boundaries is, therefore, considered as a key enabler for the development of profitable PSS. The paper is based on ...
The Philosopher's Stone for Sustainability, 2013
Total Offers, Functional Products, and Integrated Product Service Engineering reflect a shift tow... more Total Offers, Functional Products, and Integrated Product Service Engineering reflect a shift toward service offers from manufacturing industry captured within the term Product-Service Systems (PSS). Manufacturing companies have traditionally focused design and development activities on realizing technical and engineered aspects of physical artifacts, while PSS include deeper understanding of customers' expectation, needs and perceived value, hence calling for modelling of additional aspects. The change in early design ...
The main aim of this paper is to present a methodology developed within the European Project VIVA... more The main aim of this paper is to present a methodology developed within the European Project VIVACE to guide the design and implementation of a Knowledge Enabled Engineering (KEE) system in a Virtual Enterprise. The proposed methodology tries to overcome some of the limitations which characterise traditional methods for Target Cascading, promoting a more collaborative and iterative approach to derive system specifications (in terms of advanced knowledge functionalities) from initial high-level targets. Social and behavioural aspects of Knowledge Management play a crucial role when many different users, knowledge experts, and process owners are involved in the Knowledge Management System (KMS) development. A well designed methodology is needed, therefore, to enhance communication and information sharing among design teams, to promote requirements merging and to take care both of the technological and behavioural aspects of the implementation. Initial business targets have been step-by-step decomposed into a set of sub-problems (Service Requirements, Knowledge Issues, and Knowledge Challenges) in the form of simple sentences in natural language. Then Quality Function Deployment (QFD) matrixes have been used to identify the set of functionalities to be implemented in the system, addressing the most important knowledge-related problems outlined in the cascading activity.
Design Science
As products are being developed over time and across organisations, the risk for unintended accum... more As products are being developed over time and across organisations, the risk for unintended accumulation and mis-conception of margins allocated may occur. Accumulation of margins can result in over design, but also add risk due to under allocation. This paper describes the different terminology used in one organisation and shows the different roles margins play across the design process and in particular the how margins are a critical but often overlooked aspect of product platform design. The research was conducted in close collaboration with a truck manufacturer between 2013 and 2018. The objective was to gain understanding of the current use of margins, and associated concepts evolve along the product life cycle, across organisation and product platform representations. It was found that margins already play an important role throughout the entire design process; however, it is not recognised as a unified concept which is clearly communicated and tracked throughout the design pr...