[ASEP-Prep] #6. Quality Characteristics

In this post, we will briefly summarize the QC contents of the SE Handbook.

Quality Characteristics

ISO/IEC/IEEE 15288 (2023) defines Quality Characteristics (QC) as inherent characteristics related to the requirements of a product, process or system. QC is the standard by which stakeholders judge the quality of the system. There are many different approaches to applying QC to a system or its environment, which can create non-functional requirements. QC approaches such as safety, security, and resilience can also generate functional requirements. These QC approaches apply throughout the entire life cycle of the system and must also take into account factors external to the system.

This image shows relationships between Quality Characteristics with Life Cycle

1. Affordability Analysis

Affordability analysis is an approach that evaluates the balance between performance, cost, and schedule constraints of a system and maximizes the value of the system while meeting mission requirements with strategic investments and organizational needs. According to INCOSE, this analysis defines system affordability as balancing cost, performance and schedule by providing cost-effective capabilities throughout the system life cycle.

Affordability analysis is especially important when designing and developing complex systems, ensuring maximum performance within budget and progressing projects in a way that meets strategic goals. These analyzes contribute to long-term cost savings, increased efficiency, and successful completion of projects.

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2. Agility Engineering

Agility Engineering provides an approach that allows you to respond quickly and cost-effectively to change. It centers around flexibility – the ability to respond effectively in uncertain and unpredictable environments. Flexibility is measured by delivering value in a timely manner, being able to repeat costs as often as needed, predictability to meet needs, and comprehensiveness across mission boundaries. Flexible system engineering and flexible system engineering are different.

The former refers to the engineering process itself being carried out in a flexible manner, and the latter refers to a system in which the results created through the engineering process are flexible. Both approaches are based on architectural patterns and design principles, which enable sustainable flexibility. This approach helps organizations adapt effectively to changing requirements and environments.

3. Human Systems Integration

Human Systems Integration (HSI) is an approach to systems engineering (SE) that effectively integrates technology, organization, and human factors. HSI uses sociotechnical and managerial methods to appropriately address the technical, organizational and human elements of a system throughout its life cycle. This approach takes into account the interaction between human and technological elements in the operating environment, helping systems operate harmoniously and cost-effectively.

HSI includes all stakeholders involved in the system: users, maintenance personnel, and the general public. In addition, HSI aims for the integration of human and technological elements, the efficient coordination of diverse perspectives, and attaches importance to systems being designed to take human capabilities and limitations into account. This integration supports system design, analysis, and evaluation activities, helping to understand and effectively integrate technical, organizational, and human factors holistically.

4. Interoperability Analysis

Interoperability Analysis is an approach designed to help various systems interact effectively. This refers to the ability of systems to work together to achieve results, including examples such as mobile phones operating on different networks around the world, or agricultural equipment from different companies being compatible with each other.

Interoperability considers factors that affect performance between systems, including social, political, and organizational factors. Interoperability plays a key role, especially in building systems of systems (SoS), which enable elements of large, complex systems to work integratedly toward a common purpose. Achieving interoperability can be achieved in two ways: by agreeing on interfaces based on open standards, or by defining and implementing custom interfaces as needed. This approach is becoming increasingly common in ‘plug and play’ consumer products.

5. Logistics Engineering

Logistics Engineering, or Product Support Engineering, is a field of engineering that focuses on identifying, acquiring, procuring, and providing necessary support resources throughout the life cycle of a system. This includes engineering supportability into the design and considering logistics at all stages of the life cycle.

The main goals of logistics engineering are to determine support requirements, design the supportability of the system, acquire and procure the necessary support, and provide cost-effective logistics support during the use and support phases of the system. This field has evolved into Supply Chain Management (SCM) in the commercial sector and Integrated Logistics Support (ILS) in the defense sector, and plays a critical role in supporting the efficient maintenance and operation of systems.

6. Manufacturability/Producibility Analysis

Manufacturability/Producibility Analysis is an important approach that enables responsible and cost-effective production of systems. This analysis is an essential part of the systems engineering process, where manufacturability is of equal importance to the ability to properly develop a system. Systems that do not consider manufacturability/producibility can result in unnecessary costs and project delays.

Manufacturability depends on the type and quantity of systems being produced; some systems, such as infrastructure, are produced on-site. It is important to determine whether production support systems are sufficiently efficient, and if they are insufficient, new production support systems and processes must be developed. These analyzes play a key role in optimizing production processes and ensuring that systems meet market demands.

7. Reliability, Availability, Maintainability Engineering

Reliability, Availability, and Maintainability (RAM) engineering is an approach that ensures that a system operates without failure (Reliability), is available when needed (Availability), and is maintained or restored to the required functional state (Maintainability). RAM should be considered not only as a quality characteristic but also as a non-functional requirement. RAM activities are often neglected during system development, resulting in a significant increase in risk that can lead to project failure or stakeholder dissatisfaction.

Because RAM drives other system requirements, it is essential to select, customize, plan, and execute these activities in integration with the Systems Engineering (SE) process. A practical approach is to develop a detailed reliability and maintenance plan early in system development and integrate it with the SE Management Plan (SEMP). RAM supports other SE processes in two ways: by influencing system and system support definitions, and by being used as part of system verification. Depending on the specific industry, availability is considered the most important of these three quality characteristics from the user’s or acquirer’s perspective, and loss of availability can usually easily translate into loss of mission or production and increased costs.

8. Resilience Engineering

Resilience engineering is an approach to designing systems that provide the capabilities needed in the face of adversity. This concept, which first appeared in 2006 and became widely recognized in 2010, encompasses the survivability of a system and has been given various definitions. The resilience of an engineered system refers to its ability to continue to provide required functionality even in the face of adversity.

While typical system development focuses on functionality under normal conditions, resilience aims to ensure that the system can maintain functionality under adverse conditions. This involves identifying the functions required of the system, the negative conditions under which the system must provide the functions, and the structure and design that can ensure this. Resiliency focuses on providing needed functionality rather than maintaining structure or organization. This can be achieved through system continuity as well as adaptability.

9. Sustainability Engineering

Sustainability engineering is an approach that supports a circular economy throughout its life. Sustainable design is defined as the process of considering environmental and social aspects as key factors throughout the entire life cycle of a product, resulting in environmentally conscious decisions that promote responsible disposal practices that conserve scarce resources through product recycling and material reuse.

Includes. Sustainability and disposability are key components of the circular economy, which is based on production and consumption models that include sharing, reusing, repairing and recycling existing products and materials wherever possible. This aims to extend the life cycle of products, minimize waste and pollution, and create closed-loop systems. These goals are consistent with the 2030 Sustainable Development Goals adopted by all United Nations member states in 2015.

10. System Safety Engineering

Systems safety engineering is an approach to reducing harm to people, assets, and the environment, with the goal of reducing the safety risks of engineered systems to an acceptable level. Safety cannot be 100% guaranteed, and safety standards and regulations vary by industry and country. This goes beyond simply ensuring that the system is considered safe, but also minimizes the risk to everyone involved in the production, use, support and decommissioning of the system and to any third parties who may be affected by the activities.

Key activities include designing safe systems, technologically mitigating or procedurally controlling risks. System safety considers operating in complex socio-technical environments, making it important to understand and align the mental models of designers, operators, and managers. Additionally, it is necessary to continuously monitor that design assumptions are valid, that no new hazards are present, and that operations and maintenance are performing as expected.

System safety engineering also focuses on preventing misuse of the system, ensuring that leaders create the right culture, and that maintenance tasks do not take shortcuts. All of this, along with appropriately qualified personnel, effective processes, and appropriate governance and culture, is essential to manage and improve the safety of the system.

11. System Security Engineering

Systems security engineering (SSE) is an engineering approach that identifies, protects against, detects, responds to, and recovers from unusual and destructive events. This takes into account incidents related to misuse and malicious conduct, including the competitive environment in cyberspace. SSE analyzes security threats and vulnerabilities in systems, assesses and mitigates security risks to system assets, and continuously maintains security throughout their life cycle. This approach is designed to blend technology, management principles and operational rules to ensure adequate protection at all times.

Threats can come from external sources (e.g. theft, denial-of-service attacks, power outages) or internal causes (e.g. user behavior, support systems), and disruptions can be intentional or unintentional. Physical security involves multiple layers of security systems that protect systems from unauthorized access, misuse, or damage. As increasing digitalization makes hardware and software systems more vulnerable to threats using digital technologies, SSE addresses security issues by integrating them at each stage of the life cycle, making them part of the overall SE solution rather than separate from SE activities.

SSE plays an important role in reducing the impact of modern adversities, for example attacks by advanced adversaries, by providing reliable security systems. It expands the concept of trustworthiness to include trustworthiness, privacy, safety, and resilience, along with cybersecurity management to include confidentiality, integrity, and availability of information assets.

12. Loss-Driven Systems Engineering

Loss-Driven Systems Engineering (LDSE) is an approach that integrates the potential losses associated with the development and use of systems. While traditional SE methodologies focus on functional delivery, LDSE focuses attention on loss-centric quality characteristics (QCs) such as resilience, safety, security, sustainability/disposability, and availability.

To leverage the commonalities and synergies between these QCs, LDSE works collaboratively, taking into account adversity, defects, risks, and vulnerabilities. Additionally, SE professionals must integrate these requirements into system design and risk management to make holistic decisions.

[ASEP-Prep] #1. What is System LIFE CYCLE?

[ASEP-Prep] #2. Agreement and Enabling Processes

[ASEP-Prep] #3. Technical Management Processes

[ASEP-Prep] #4. Technical Processes – Concept and System Definition

[ASEP-Prep] #5. Technical Processes – System Realization, Deploy and Use



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