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Risk is the possibility of a hazardous event occurring that will have an impact on the achievement of objectives. Risk is measured in terms of consequence (or impact) and likelihood of the event. Qualitatively, risk is considered proportional to the expected losses which can be caused by an event and to the probability of this event. Quantatively, it is the product of probability of hazardous event and the consequences. General views about risk perception and risk communication are discussed that help decision making. Risk management and risk governance along with probabilistic risk assessment and alternative approaches to risk analysis are also discussed.

This chapter is intended to introduce some of the areas of applications of performability engineering that have been presented in this handbook. Only the areas of current interest and importance have been included. It is expected that the chapters will accelerate the process of bringing about synergetic interaction between the practioners of performability engineering in several other relevant areas of applications.

The most important attribute of performance is reliability and this is defined as the probability of failure free operation over a specified duration of time under a given set of conditions, which depend on location and the kind of application the item is put to. In designing for reliability, the objective must be to maximize inherent and operational reliability such that occurrences of failures are considerably reduced. Component or system reliability goals can be achieved through design and testing. Failures and consequently accidents can be avoided if their causes of can be traced and taken care of during the design process.

Maintenance is another important aspect of system performance after reliability. There are several facets of maintenace management, and in this introductory chapter we would like to have these surveyed. Broadly speaking, maintenance is the process of maintaining equipment in its operational state either by preventing its transition to a failed state or by restoring it to an operational state following a failure. This leads to various types of maintenace activities that can be planned to realize the objective of maitenance, such as preventive, predictive, or corrective. Recent developments in maintenance engineering and management are also discussed in this chapter.

Sustainability is a characteristic of a process or state that can be maintained at a certain level indefinitely. Sustainability focuses on providing the best outcomes for both human and natural environments now, and indefinitely into the future. In recent years, academic interest and public discussion has led to the use of the word sustainability in reference to how long human ecological systems can be expected to be usefully productive. This chapter first examines the threats and then provides how the environmental threats can be assessed and mitigated.

For better system performance, attributes such as quality, reliability, maintainability, safety, and risk that are closely related and govern the dependability of the system, must be considered. It is also necessary to understand the inter-relationship between these factors so that one not only minimizes the chances of occurrence of any untoward incident at the design and fabrication stage but also minimizes the chances of occurrences and the consequences of such an event during the system operation and use phase.

Reliability is one of the most important attributes of performance in arriving at the optimal design of a system since it directly and significantly influences the system’s performance and its life cycle costs. Poor reliability would greatly increase life-cycle costs of the system, and reliability based design must be carried out if the system is to achieve its desired performance. An optimal reliability design is one in which all possible means available to a designer have been explored to enhance the reliability of the system with minimum cost under the constraints imposed on the development of a system.

All production processes employ materials, men and machines. Each of these elements has some inherent variability in addition to attributable variability, which can be controlled to an irreducible economic minimum. The subject of quality engineering and management is about reducing the variablity in products and processes, quality costs and to provide maximum satisfaction to the customers through improved product performance. The subject has grown considerably since 1930, when Shewhart first developed his statistical approach to quality. Several developments that have taken place since then are presented in this chapter along with quality planning, control, assurance and improvement, which form the backbone of any quality program.

The concept of performability is explained and the desirability of using this attribute in pursuing the design of engineering products, systems, and services is emphasized in order to meet the challenges of the 21st century. Today a new revolution is taking place where the leaders will be those nations that provide priority to the principles of sustainability in order to design, develop and use products, systems and services that are not only dependable but do not lead to disrupt the delicate ecological balance in nature. New materials, technologies and processes in consonance with environmental protection hold the key to future progress and prosperity.

The purpose of this chapter is not to deal with all the aspects of design of an engineering system, but to discuss the design process using the systems approach, which the design department or section of a manufacturing concern, particularly in the electronics, aerospace, machine tool sector and the producers of consumer goods such as automobiles, office equipment, and household appliances and in many other areas, can use. For a manufacturer, the research function helps develop new products or useful design modifications to an existing product range and development activity, which is basically an engineering function aimed at converting the research concept into a viable product, is known as an R&D activity and sometimes it may be associated with design engineering as a project design and development function.

The performance of a product, a system or a service is usually judged in terms of dependability (which can be defined as an aggregate of quality, reliability, and maintainability etc.) and safety, not overlooking the cost of achieving these attributes. As of now, dependability and cost effectiveness are primarily seen as instruments for conducting the international trade in the free market environment and thereby deciding the economic prosperity of a nation. However, the internalization of the hidden costs of environment preservation will have to be accounted for, sooner or later, in order to be able to produce sustainable products in the long run. These factors cannot be considered in isolation of each other. The Handbook of Performability Engineering considers all aspects of performability engineering, providing a holistic view of the entire life cycle of activities of the product, along with the associated cost of environmental preservation at each stage, while maximizing the performance.