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[[File:A sample Design Structure Matrix (DSM).png|273x193px|framed|right|A sample DSM with 7 elements and 11 dependency marks.]]
The '''Design Structure Matrix (DSM)''' (also referred to as '''dependency structure matrix''', '''dependency structure method''', '''dependency source matrix''', '''problem solving matrix (PSM)''', '''incidence matrix''', '''''N<sup>2</sup>'' matrix''', '''interaction matrix''', '''dependency map''' or '''design precedence matrix''') is a simple, compact and visual representation of a system or project in the form of a square [[matrix (mathematics)|matrix]].<ref name="DSMbook">S.D. Eppinger and T.R. Browning, Design Structure Matrix Methods and Applications, [http://mitpress.mit.edu/books/design-structure-matrix-methods-and-applications], MIT Press, Cambridge, 2012.</ref>
It is the equivalent of an [[adjacency matrix]] in [[graph theory]], and is used in [[systems engineering]] and [[project management]] to model the structure of complex systems or processes, in order to perform system analysis, project planning and organization design. [[Don Steward]] coined the term "design structure matrix" in
== Overview ==
A design structure matrix lists all constituent [[subsystem]]s/[[Activity diagram|activities]] and the corresponding [[information exchange]],interactions, and dependency [[Pattern recognition|patterns]]. For example, where the matrix elements represent activities, the matrix details what pieces of information are needed to start a particular activity, and shows where the information generated by that activity leads. In this way, one can quickly recognize which other activities are reliant upon information outputs generated by each activity.
The use of DSMs in both research and industrial practice increased greatly in the 1990s. DSMs have been applied in the building construction, real estate development, semiconductor, automotive, photographic, aerospace, telecom, small-scale manufacturing, factory equipment, and electronics industries, to name a few, as well as in many government agencies.<ref name="DSMbook"/>
The matrix representation has several strengths.
* The matrix can represent a large number of [[Systems theory|system]] elements and their relationships in a compact way that highlights important patterns in the data (such as [[feedback loop]]s and modules).
* The presentation is amenable to matrix-based analysis techniques, which can be used to improve the structure of the system.
* In modeling activities precedence it allows representing feedback linkages that cannot be modeled by [[Gantt chart]]/[[Program evaluation and review technique|PERT]] modeling techniques <ref>Browning TR, Fricke E, Negele H (2006) [http://sbuweb.tcu.edu/tbrowning/Publications/Browning%20Fricke%20Negele%20(2006)--Process%20Modeling%20Concepts.pdf "Key
DSM analysis provides insights into how to manage complex systems or projects, highlighting [[information flow]]s, task/activities sequences and iteration.<ref name="DSMbook"/><ref name="complex">Yassine A, Braha D (2003),[http://necsi.edu/affiliates/braha/CERA.pdf "Complex Concurrent Engineering and the Design Structure Matrix Approach."] Concurrent Engineering: Research and Applications, 11(3):165-177</ref> It can help teams to streamline their processes based on the optimal flow of information between different interdependent activities.
DSM analysis can also be used to manage the effects of a change. For example, if the specification for a component had to be changed, it would be possible to quickly identify all processes or activities which had been dependent on that specification, reducing the [[Risk management|risk]] that work continues based on out-of-date information.<ref name="DSMbook"/>
==DSM Structure==
A DSM is a [[square matrix]], representing linkages between the system elements. The system elements are often labeled in the rows to the left of the matrix and/or in the columns above the matrix. These elements can represent for example product components, organization teams, or project activities.
The off-diagonal cells are used to indicate relationships between the elements. A marking of the cell indicates a directed link between two elements and can represent design relations or constraints between product components, communication between teams, information flow or precedence relations between activities.
The cells along the diagonal are typically used to represent the system elements. However, the diagonal cells can be used for representing self-iterations (e.g., rework of a code that did not pass its unit testing). Self-iterations are required when a matrix element represents a block of activities/subsystems that may be further detailed, allowing hierarchical DSM structure.<ref>A. Karniel and Y. Reich, “Simulating Design Processes with self-iteration activities based on DSM planning,” in Proceedings of the International Conference on Systems Engineering and Modeling - ICSEM'07, Haifa, 2007. [http://www.researchgate.net/publication/4255493_Simulating_Design_Processes_with_self-iteration_activities_based_on_DSM_planning]</ref>
Two main categories of DSMs have been proposed: static and time-based.<ref name="DSMreview">T. Browning:
Static DSMs represent systems where all of the elements exist simultaneously, such as components of a machine or groups in an organization. A static DSM is equivalent to an ''N<sup>2</sup>''
A time-based DSM is akin to a [[precedence diagram]] or the matrix representation of a [[directed graph]]. In time-based DSMs, the ordering of the rows and columns indicates a flow through time: earlier activities in a process appear in the upper-left of the DSM and later activities appear in the lower-right. Terms like “feedforward” and “feedback” become meaningful when referring to interfaces. A feedback mark is an above-diagonal mark (when rows represent output). Time-based DSMs are typically analyzed using sequencing algorithms, that reorder the matrix elements to minimize the amount of feedback marks, and make them as close as possible to the diagonal.<ref name="DSMbook"/>
DSM matrices were categorized to Component-based or Architecture DSM; People-based (Team-based) or Organization DSM, both considered as Static (representing existing elements). Activity-based or Schedule DSM and Parameter-based DSM are defined as time-based, as their ordering implies flow.
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==DSM algorithms==
The DSM algorithms are used for reordering the matrix elements subject to some criteria. Static DSMs are usually analyzed with [[Cluster analysis|clustering algorithms]] (i.e., reordering the matrix elements in order to group together related elements). Clustering results would typically show groups (clusters) of tightly related elements, and elements that are either not connected or are connected to many other elements and therefore are not part of a group.<ref name="
Time-based DSMs are typically analyzed using partitioning, tearing and sequencing algorithms.<ref name="DSMbook"/><ref name="complex"/><ref>A. Karniel and Y. Reich, "Design process planning using DSM", Managing the Dynamics of New Product Development Processes: A New Product Lifecycle Management Paradigm, Springer, 2011 [http://link.springer.com/chapter/10.1007%2F978-0-85729-570-5_3]</ref>
'''
'''Tearing''' is the removal of feedback marks (in Binary DSM) or assignment of lower priority (numeric DSM). Tearing of a Component-based DSM may imply modularization (the component design is not influencing other components) or standardization (the component design is not influencing and not influenced by other components).<ref name="DSMbook"/><ref name="complex"/><ref>Sered Y, Reich Y (2006)," Standardization and modularization driven by minimizing overall process effort." Computer-Aided Design, 38(5):405-416</ref> After tearing a partitioning algorithm is (re)applied.
Minimizing feedback loops gets the best results for Binary DSM, but not always for Numeric DSM or Probability DSM. '''Sequencing''' algorithms (using optimization, genetic algorithms) are typically trying to minimize the number of feedback loops and also to reorder coupled activities (having cyclic loop) trying to have the feedback marks close to the diagonal. Yet, sometimes the algorithm just tries to minimize a criterion (where minimum iterations is not the optimal results).<ref name="DSMsim">T. Browning: [http://dx.doi.org/10.1109/TEM.2002.806709 "Modeling Impacts of Process Architecture on Cost and Schedule Risk in Product Development"], In: ''IEEE Transactions on Engineering Management.'' 49(4):428-442, 2002.</ref>
==Use and extensions==
Interactions between various aspects (people, activities, and components) is done using additional (non-square) linkage matrices. The Multiple Domain Matrix (MDM) is an extension of the basic DSM structure.<ref>Maurer M (2007) Structural Awareness in complex product design. Dissertation, Technischen Universität München, Germany</ref> A MDM includes several DSMs (ordered as block diagonal matrices) that represent the relations between elements of the same ___domain; and corresponding Domain Mapping Matrices (DMM) <ref>M. Danilovic; T. R. Browning:
The use of DSM has been extended to visualize and optimize the otherwise invisible information flow and interactions associated with office work. This visualization via DSM allows the Lean Body of Knowledge to be applied to office and information intensive flows.<ref>{{cite book|title=Far From the Factory: Lean for the Information Age|year=2010|publisher=Productivity Press|___location=New York|isbn=1420094564|pages=159–180}}</ref>
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==Additional links==
*Web-Portal of DSM Community: http://www.dsmweb.org
*
*DSM book: http://mitpress.mit.edu/books/design-structure-matrix-methods-and-applications
*[http://www.theserverside.net/tt/articles/showarticle.tss?id=ControllingDependencies Control Component Dependencies, TheServerSide.net article]
*[http://hbswk.hbs.edu/archive/1979.html Innovation at the Speed of Information]
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