Difference between pages "System Design" and "System Maintenance"

From SEBoK
(Difference between pages)
Jump to: navigation, search
(Tech and grammar edits as discussed with Bkcase)
 
(Tech and grammar edits as discussed with Bkcase)
 
Line 1: Line 1:
 
----
 
----
'''''Lead Authors:''''' ''Alan Faisandier, Rick Adcock''
+
'''''Lead Authors:''''' ''Scott Jackson, Brian Gallagher'', '''''Contributing Author:''''' ''David Dorgan''
 
----
 
----
The purpose of the System Design is to supplement the system architecture by providing information and data useful and necessary for implementation of the system elements. Design definition is the process of developing, expressing, documenting, and communicating the realization of the architecture of the system through a complete set of design characteristics described in a form suitable for implementation.
+
{{Term|Maintenance (glossary)|System Maintenance}} planning begins early in the acquisition process with development of a maintenance concept. Maintenance planning is conducted to evolve and establish requirements and tasks to be accomplished for achieving, restoring, and maintaining operational capability for the life of the system. For a {{Term|System (glossary)|system}} to be sustained throughout its {{Term|Life Cycle (glossary)|system life cycle}}, the maintenance process has to be executed concurrently with the operations process ([[ISO/IEC/IEEE 15288]] 2015, Clause 6.4.9).
  
== Concepts and Principles ==
+
==Overview==
 +
The initial requirements for maintenance have to be defined during the [[Stakeholder Needs and Requirements|stakeholder needs and requirement definition process]] (Clause 6.4.1) ([[ISO/IEC/IEEE 15288]] 2015) and continue to evolve during the development and operation of the system. Considerations include:
  
=== Design Notion ===
+
* Maximizing system availability to meet the operational requirements. This has to take into account the designed-in {{Term|Reliability (glossary)|reliability}} and {{Term|Maintainability (glossary)|maintainability}} of the system and resources available.
In industrial practices, the term ''design'' is often used to mean both {{Term|Architecture (glossary)}} and {{Term|Design (glossary)}}. In the recent past, professionals used the term ''design'' when they dealt with simpler technological products - ones that do not include several different and interconnected technological components such as hardware, software, operators, services, etc. In the development of new multi-technology products and services, professionals have recognized the usefulness of the notion of ''system'' in dealing with {{Term|complexity (glossary)}} (interconnections level, multi-techno, emergence, etc.).
+
* Preserving system operating potential through proper [[Planning|planning]] of system scheduled maintenance. This requires a reliability-centered maintenance strategy that incorporates preventive maintenance in order to preempt failures, thereby extending the mean time between corrective maintenance, as well as enhancing the availability of the system.
 +
* Segmenting maintenance activities for potential outsourcing of non-critical activities to approved maintenance subcontractors as to optimize scarce technical manpower resources and maintenance/repair turn-around times.
 +
* Harnessing IT technology for maintenance management. This involves rigorous and systematic capturing and tracking of operating and maintenance activities to facilitate analysis and planning.
  
It was due to complexity that structuring the elements that comprise a system became necessary. This structure explains the functional, behavioral, temporal, physical, and other aspects of a system as described in [[System Architecture]]. Practitioners found the term ''structure'' inadequate to describe all these aspects of a system. The terms ''architecture'' and ''architectural design'' have been used for approximately 30 years, especially in software intensive systems and other domains, such as the space industry. The set of different types and interrelated structures can be understood as the architecture of the system.
+
Maintenance management is concerned with the development and review of maintenance plans, as well as securing and coordinating resources, such as budget, service parts provisioning, and management of supporting tasks (e.g., contract administration, engineering support, and quality assurance). Maintenance planning relies on level of repair analysis (LORA) as a function of the system acquisition process. Initial planning addresses actions and support necessary to ensure a minimum {{Term|Life Cycle Cost (LCC) (glossary)|life cycle cost}} (LCC).
  
The trend today is to consider system architecture and system design as different and separate sets of activities, but concurrent and strongly intertwined.
+
==Process Approaches==
 +
The purpose of the maintenance process is to sustain the capability of a system to provide a service. This process monitors the system’s capability to deliver services, records problems for analysis, takes corrective, adaptive, perfective, and preventive actions, and confirms restored capability. As a result of the successful implementation of the maintenance process:
  
System design includes activities to conceive a set of system elements that answers a specific, intended purpose, using principles and concepts; it includes assessments and decisions to select system elements that compose the system, fit the architecture of the system, and comply with traded-off system requirements. It is the complete set of detailed models, properties, and/or characteristics described into a form suitable for implementation.
+
* a maintenance strategy is developed
 +
* maintenance constraints are provided as inputs to requirements
 +
* replacement system elements are made available
 +
* services meeting stakeholder requirements are sustained
 +
* the need for corrective design changes is reported
 +
* failure and lifetime data are recorded
  
=== Design Characteristics and Design Enablers ===
+
The project should implement the following activities and tasks in accordance with applicable organization policies and procedures with respect to the maintenance process:
Every technological domain or discipline owns its peculiar laws, rules, theories, and enablers concerning transformational, structural, behavioral, and temporal properties of its composing parts of materials, energy, or information. These specific parts and/or their compositions are described with typical design characteristics and enablers. These allow achieving the implementation of every system element through various transformations and exchanges required by design characteristics (e.g., operability level, reliability rate, speed, safeguard level) that have been assigned during the system architecture definition process.
+
* scheduled servicing, such as daily inspection/checks, servicing, and cleaning
 +
* unscheduled servicing (carrying out fault detection and isolation to the faulty replaceable unit and replacement of the failed unit)
 +
* re-configuration of the system for different roles or functions
 +
* scheduled servicing (higher level scheduled servicing but below depot level)
 +
* unscheduled servicing (carrying out more complicated fault isolation to the faulty replaceable unit and replacement of the failed unit)
 +
* minor modifications
 +
* minor damage repairs
 +
* major scheduled servicing (e.g., overhaul and corrosion treatment)
 +
* major repairs (beyond normal removal and replacement tasks)
  
The design definition provides the description of the design characteristics and design enablers necessary for implementation. Design characteristics include dimensions, shapes, materials, and data processing structures. Design enablers include formal expressions or equations, drawings, diagrams, tables of metrics with their values and margins, patterns, algorithms, and heuristics.
+
The maintenance plan specifies the scheduled servicing tasks and intervals (preventive maintenance) and the unscheduled servicing tasks (adaptive or corrective maintenance). Tasks in the maintenance plan are allocated to the various maintenance agencies. A maintenance allocation chart is developed to tag the maintenance tasks to the appropriate maintenance agencies. These include: in-service or in-house work centers, approved contractors, affiliated maintenance or repair facilities, original equipment manufacturer (OEMs), etc. The maintenance plan also establishes the requirements for the support resources.
* Examples of generic design characteristics in mechanics of solids: shape, geometrical pattern, dimension, volume, surface, curves, resistance to forces, distribution of forces, weight, velocity of motion, temporal persistence
 
* Examples of generic design characteristics in software: distribution of processing, data structures, data persistence, procedural abstraction, data abstraction, control abstraction, encapsulation, creational patterns (e.g., builder, factory, prototype, singleton), and structural patterns (e.g., adapter, bridge, composite, decorator, proxy)
 
  
=== Relation with System Architecture ===
+
Related activities such as resource planning, budgeting, performance monitoring, upgrades, longer term supportability, and sustenance also need to be managed. These activities are planned, managed, and executed over a longer time horizon and they concern the well-being of the system over the entire life cycle.
System design is intended to be the link between the system architecture (at whatever point this milestone is defined in the specific application of the systems engineering process) and the implementation of technological system elements that compose the physical architecture model of the system.
 
  
Design definition is driven by specified requirements, the system architecture, and more detailed analysis of performance and feasibility. It addresses the implementation technologies and their assimilation. Design provides the “how-” or “implement-to” level of the definition.
+
Proper maintenance of the system (including maintenance-free system designs) relies very much on the availability of support resources, such as support and test equipment (STE), technical data and documentation, personnel, spares, and facilities. These have to be factored in during the acquisition agreement process.
  
Design concerns every system element composed of implementation technologies, such as mechanics, electronics, software, chemistry, human operations and services for which specific engineering processes are needed. System design provides feedback to the parent system architecture to consolidate or confirm the allocation and partitioning of architectural characteristics and design properties to system elements.
+
==Training and Certification==
  
=== Design Descriptor ===
+
Adequate training must be provided for the technical personnel maintaining the system. While initial training may have been provided during the deployment phase, additional personnel may need to be trained to cope with the increased number of systems being fielded, as well as to cater to staff turnover. Timely updates to training materials and trained personnel may be required as part of system upgrades and evolution.  It is important to define the certification standards and contract for the training materials as part of the supply agreement.
A design descriptor is the set of generic design characteristics and of their possible values. If similar, but not exact system elements exist, it is possible to analyze these in order to identify their basic characteristics. Variations of the possible values of each characteristic determine potential candidate system elements.
 
  
=== Holistic Design ===
+
==Practical Considerations==
Holistic design is an approach that considers the system being designed as an interconnected whole, which is also part of something larger. Holistic concepts can be applied to the system as a whole along with the system in its context (e.g., the enterprise or mission in which the system participates), as well as the design of mechanical devices, the layout of spaces, and so forth. This approach often incorporates concerns about the environment, considering how the design will impact the environment and attempting to reduce environmental impact. Holistic design is about more than merely trying to meet the system requirements.
 
  
== Process Approach ==
+
The organization responsible for maintaining the system should have clear thresholds established to determine whether a change requested by end users, changes to correct latent defects, or changes required to fulfill the evolving mission are within the scope of a maintenance change or require a more formal project to step through the entire systems engineering life-cycle. Evaluation criteria to make such a decision could include cost, schedule, risk, or criticality characteristics.
  
=== Purpose ===
+
==References==  
The purpose of the System Design process is to provide sufficient detailed data and information about the system and its system elements to enable the implementation consistent with architectural entities as defined in models and views of the system architecture (ISO/IEC/IEEE 15288 [ISO 2015]).
 
  
Generic inputs include architecture description of the parent system and system element requirements.
+
===Works Cited===
 +
ISO/IEC/IEEE. 2015.''[[ISO/IEC/IEEE 15288|Systems and Software Engineering - System Life Cycle Processes]].''Geneva, Switzerland: International Organization for Standardization (ISO)/International Electrotechnical Commission (IEC), Institute of Electrical and Electronics Engineers (IEEE). [[ISO/IEC/IEEE 15288]]:2015.
  
Generic outputs are the description of the design characteristics and design enablers necessary for implementation.
+
===Primary References===
 +
Blanchard, B.S. and W.J. Fabrycky. 2011. ''[[Systems Engineering and Analysis]],'' 5th Edition. Upper Saddle River, NJ, USA: Prentice Hall.
  
=== Activities of the Process ===
+
DAU. 2010. ''[[Defense Acquisition Guidebook (DAG)]]''. Ft. Belvoir, VA, USA: Defense Acquisition University (DAU)/U.S. Department of Defense.
Major activities and tasks to be performed during this process include the following:
 
  
==== 1. Initialize design definition ====
+
INCOSE. 2012. ''[[INCOSE Systems Engineering Handbook]]: A Guide for System Life Cycle Processes and Activities''. Version 3.2.2. San Diego, CA, USA: International Council on Systems Engineering (INCOSE), INCOSE-TP-2003-002-03.2.2.
* Plan for technology management for the whole system. Identify the technologies (mechanics, electricity, electronics, software, biology, operators, etc.) that would compose and implement the system elements and their physical interfaces.
 
* Determine which technologies and system elements have a risk to become obsolete or evolve during the operation stage of the system. Plan for their potential replacement.
 
* Identify types of design characteristics or properties for each technology of each system element.
 
* Periodically assess design characteristics and adjust as the system evolves.
 
* Document the design definition strategy, including the need for and requirements of any enabling systems, products, or services to perform the design.
 
  
==== 2. Establish design characteristics and design enablers related to each system element ====
+
Institute of Engineers Singapore. 2009. ''[[Systems Engineering Body of Knowledge (Singapore)|Systems Engineering Body of Knowledge]],'' Provisional version 2.0. Singapore: Institute of Engineers Singapore.
* Perform, consolidate or detail system requirements allocation to system elements for all requirements and system elements not fully addressed in the System Architecture process (normally, every system requirement would have been transformed into architectural entities and architectural characteristics within the System Architecture process, which are then allocated to system elements through direct assignment or some partitioning).
 
* Define the design characteristics relating to the architectural characteristics and check that they are implementable. Use design enablers, such as models (physical and analytical), design heuristics, etc. If the design characteristics are not feasible, then assess other design alternatives or implementation option, or perform trades of other system elements definition.
 
* Define the interfaces that were not defined by the System Architecture process or that need to be refined as the design details evolve. This includes both internal interfaces between the system elements and the external interfaces with other systems.
 
* Record the design characteristics of each system element within the applicable artifacts (they depend on the design methods and techniques used).
 
* Provide rationale about selection of major implementation options and enablers.
 
  
==== 3. Assess alternatives for obtaining system elements ====
+
IISO/IEC/IEEE. 2015.''[[ISO/IEC/IEEE 15288|Systems and Software Engineering - System Life Cycle Processes]].'' Geneva, Switzerland: International Organization for Standardization (ISO)/International Electrotechnical Commission (IEC), Institute of Electrical and Electronics Engineers (IEEE).[[ISO/IEC/IEEE 15288]]:2015.
* Identify existing implemented system elements (COTS/NDI, reused, or other non-developed system elements). Alternatives for new system elements to be developed may be studied.
 
* Assess design options for the system element, using selection criteria that are derived from the design characteristics.
 
* Select the most appropriate alternatives.
 
* If the decision is made to develop the system element, the rest of the design definition process and the implementation process are used. If the decision is to buy or reuse a system element, the acquisition process may be used to obtain the system element.
 
  
==== 4. Manage the design ====
+
===Additional References===
* Capture and maintain the rationale for all selections among alternatives and decisions for the design, architecture characteristics, design enablers, and sources of system elements.
+
None.
* Assess and control the evolution of the design characteristics, including the alignment with the architecture.
 
* Establish and maintain traceability between design characteristics and architectural characteristics, and with requirements as necessary.
 
* Provide baseline information for configuration management.
 
* Maintain the design baseline and the design definition strategy.
 
 
 
== Practical Considerations ==
 
Key pitfalls and proven practices related to system design are described in the next two sections.
 
 
 
=== Pitfalls ===
 
Some of the key pitfalls encountered in performing system design are provided in Table 1.
 
{|
 
|+
 
'''Table 1. Pitfalls with System Design.'''(SEBoK Original)
 
!Pitfall
 
!Description
 
|-
 
|'''Consider the design of each system element separately'''
 
|This would be conducted using heterogeneous implementation of a given technology or between technologies within the system-of-interest. The design strategy for the complete system is defined to find synergies and/or commonalities that could help operation and maintenance of system elements.
 
|}
 
 
 
=== Proven Practices ===
 
Some proven practices gathered from the references are provided in Table 2.
 
{|
 
|+
 
'''Table 2. Proven Practices with System Design.'''(SEBoK Original)
 
!Practice
 
!Description
 
|-
 
|'''Architecture and design mutual support'''
 
|Discipline engineers perform the design definition of each system element; they provide strong support (knowledge and competencies) to systems engineers or architects in the evaluation and selection of candidate system architectures and system elements. Inversely, systems engineers, or architects, must provide feedback to discipline engineers to improve knowledge and know-how.
 
|}
 
 
 
== References ==
 
 
 
=== Works Cited ===
 
INCOSE. 2015. ''INCOSE Systems Engineering Handbook,'' Version 4. San Diego, CA, USA: International Council on Systems Engineering (INCOSE), INCOSE-<u>TP-2003-002-03.2.2</u>.
 
 
 
ISO/IEC/IEEE. 2015. ''Systems and Software Engineering - System Life Cycle Processes.'' Geneva, Switzerland: International Organization for Standardization (ISO)/International Electrotechnical Commission (IEC)/Institute of Electrical and Electronics Engineers (IEEE). ISO/IEC/IEEE 15288:2015.
 
 
 
Faisandier, A. 2012. ''Systems Architecture and Design''. Belberaud, France: Sinergy'Com.
 
 
 
=== Primary References ===
 
 
 
ISO/IEC/IEEE. 2015. ''Systems and Software Engineering - System Life Cycle Processes.'' Geneva, Switzerland: International Organization for Standardization (ISO)/International Electrotechnical Commission (IEC)/Institute of Electrical and Electronics Engineers (IEEE). ISO/IEC/IEEE 15288:2015.
 
 
 
Faisandier, A. 2012. ''Systems Architecture and Design''. Belberaud, France: Sinergy'Com.
 
 
 
=== Additional References ===
 
Baldwin, C.Y. and K.B. Clark. 2000. ''Design Rules''. Cambridge, MA, USA: MIT Press.
 
 
 
Buede, D.M. 2009. ''The Engineering Design of Systems: Models and Methods''. 2nd ed. Hoboken, NJ, USA: John Wiley & Sons Inc.
 
 
 
DoD. 2010. ''DOD Architecture Framework.'' Version 2.02. Arlington, VA, USA: US Department of Defense. Available at: http://cio-nii.defense.gov/sites/dodaf20/
 
  
 
----
 
----
<center>[[Physical Architecture Model Development|< Previous Article]] | [[System Definition|Parent Article]] | [[System Analysis|Next Article >]]</center>
+
<center>[[Operation of the System|< Previous Article]] | [[System Deployment and Use|Parent Article]] | [[Logistics|Next Article >]]</center>
  
 
<center>'''SEBoK v. 2.1, released 31 October 2019'''</center>
 
<center>'''SEBoK v. 2.1, released 31 October 2019'''</center>
  
[[Category: Part 3]][[Category:Topic]]
+
[[Category:Part 3]][[Category:Topic]]
[[Category:System Definition]]
+
[[Category:System Deployment and Use]]

Revision as of 19:29, 2 February 2020


Lead Authors: Scott Jackson, Brian Gallagher, Contributing Author: David Dorgan


System MaintenanceSystem Maintenance planning begins early in the acquisition process with development of a maintenance concept. Maintenance planning is conducted to evolve and establish requirements and tasks to be accomplished for achieving, restoring, and maintaining operational capability for the life of the system. For a systemsystem to be sustained throughout its system life cyclesystem life cycle, the maintenance process has to be executed concurrently with the operations process (ISO/IEC/IEEE 15288 2015, Clause 6.4.9).

Overview

The initial requirements for maintenance have to be defined during the stakeholder needs and requirement definition process (Clause 6.4.1) (ISO/IEC/IEEE 15288 2015) and continue to evolve during the development and operation of the system. Considerations include:

  • Maximizing system availability to meet the operational requirements. This has to take into account the designed-in reliabilityreliability and maintainabilitymaintainability of the system and resources available.
  • Preserving system operating potential through proper planning of system scheduled maintenance. This requires a reliability-centered maintenance strategy that incorporates preventive maintenance in order to preempt failures, thereby extending the mean time between corrective maintenance, as well as enhancing the availability of the system.
  • Segmenting maintenance activities for potential outsourcing of non-critical activities to approved maintenance subcontractors as to optimize scarce technical manpower resources and maintenance/repair turn-around times.
  • Harnessing IT technology for maintenance management. This involves rigorous and systematic capturing and tracking of operating and maintenance activities to facilitate analysis and planning.

Maintenance management is concerned with the development and review of maintenance plans, as well as securing and coordinating resources, such as budget, service parts provisioning, and management of supporting tasks (e.g., contract administration, engineering support, and quality assurance). Maintenance planning relies on level of repair analysis (LORA) as a function of the system acquisition process. Initial planning addresses actions and support necessary to ensure a minimum life cycle costlife cycle cost (LCC).

Process Approaches

The purpose of the maintenance process is to sustain the capability of a system to provide a service. This process monitors the system’s capability to deliver services, records problems for analysis, takes corrective, adaptive, perfective, and preventive actions, and confirms restored capability. As a result of the successful implementation of the maintenance process:

  • a maintenance strategy is developed
  • maintenance constraints are provided as inputs to requirements
  • replacement system elements are made available
  • services meeting stakeholder requirements are sustained
  • the need for corrective design changes is reported
  • failure and lifetime data are recorded

The project should implement the following activities and tasks in accordance with applicable organization policies and procedures with respect to the maintenance process:

  • scheduled servicing, such as daily inspection/checks, servicing, and cleaning
  • unscheduled servicing (carrying out fault detection and isolation to the faulty replaceable unit and replacement of the failed unit)
  • re-configuration of the system for different roles or functions
  • scheduled servicing (higher level scheduled servicing but below depot level)
  • unscheduled servicing (carrying out more complicated fault isolation to the faulty replaceable unit and replacement of the failed unit)
  • minor modifications
  • minor damage repairs
  • major scheduled servicing (e.g., overhaul and corrosion treatment)
  • major repairs (beyond normal removal and replacement tasks)

The maintenance plan specifies the scheduled servicing tasks and intervals (preventive maintenance) and the unscheduled servicing tasks (adaptive or corrective maintenance). Tasks in the maintenance plan are allocated to the various maintenance agencies. A maintenance allocation chart is developed to tag the maintenance tasks to the appropriate maintenance agencies. These include: in-service or in-house work centers, approved contractors, affiliated maintenance or repair facilities, original equipment manufacturer (OEMs), etc. The maintenance plan also establishes the requirements for the support resources.

Related activities such as resource planning, budgeting, performance monitoring, upgrades, longer term supportability, and sustenance also need to be managed. These activities are planned, managed, and executed over a longer time horizon and they concern the well-being of the system over the entire life cycle.

Proper maintenance of the system (including maintenance-free system designs) relies very much on the availability of support resources, such as support and test equipment (STE), technical data and documentation, personnel, spares, and facilities. These have to be factored in during the acquisition agreement process.

Training and Certification

Adequate training must be provided for the technical personnel maintaining the system. While initial training may have been provided during the deployment phase, additional personnel may need to be trained to cope with the increased number of systems being fielded, as well as to cater to staff turnover. Timely updates to training materials and trained personnel may be required as part of system upgrades and evolution. It is important to define the certification standards and contract for the training materials as part of the supply agreement.

Practical Considerations

The organization responsible for maintaining the system should have clear thresholds established to determine whether a change requested by end users, changes to correct latent defects, or changes required to fulfill the evolving mission are within the scope of a maintenance change or require a more formal project to step through the entire systems engineering life-cycle. Evaluation criteria to make such a decision could include cost, schedule, risk, or criticality characteristics.

References

Works Cited

ISO/IEC/IEEE. 2015.Systems and Software Engineering - System Life Cycle Processes.Geneva, Switzerland: International Organization for Standardization (ISO)/International Electrotechnical Commission (IEC), Institute of Electrical and Electronics Engineers (IEEE). ISO/IEC/IEEE 15288:2015.

Primary References

Blanchard, B.S. and W.J. Fabrycky. 2011. Systems Engineering and Analysis, 5th Edition. Upper Saddle River, NJ, USA: Prentice Hall.

DAU. 2010. Defense Acquisition Guidebook (DAG). Ft. Belvoir, VA, USA: Defense Acquisition University (DAU)/U.S. Department of Defense.

INCOSE. 2012. INCOSE Systems Engineering Handbook: A Guide for System Life Cycle Processes and Activities. Version 3.2.2. San Diego, CA, USA: International Council on Systems Engineering (INCOSE), INCOSE-TP-2003-002-03.2.2.

Institute of Engineers Singapore. 2009. Systems Engineering Body of Knowledge, Provisional version 2.0. Singapore: Institute of Engineers Singapore.

IISO/IEC/IEEE. 2015.Systems and Software Engineering - System Life Cycle Processes. Geneva, Switzerland: International Organization for Standardization (ISO)/International Electrotechnical Commission (IEC), Institute of Electrical and Electronics Engineers (IEEE).ISO/IEC/IEEE 15288:2015.

Additional References

None.


< Previous Article | Parent Article | Next Article >
SEBoK v. 2.1, released 31 October 2019