Reetu Malhotra 6 Reliability evaluation with variation in demand Abstract: This chapter is an attempt to strengthen the reliability models that con- sider unique conditions based on the variation in demand and production capacity of systems. A brief description of models with varying demands and comparison be- tween the models taken two at a time for the system is given in this chapter. The author describes the foundation of reliability followed by different concepts intro- duced to improve reliability. She also discusses how varying demands affect the reli- ability in single-unit and two-unit redundant systems. Graphical analysis has been done to compare the systems with varying demands. Keywords: Reliability measure, redundant system, price analysis, semi-Markov approach Modern society is technical as well as technological. Being technical implies that it is being intricate in structures and substructures. Varied with instructions and catego- ries and influenced by more than one social control capabilities. If there is any place at which it fails due to stress of the subjects then it is to be maintained and mentored. Being technological implies mechanics and techniques has a thorough potential in industrialization. Advent and advancements in science and technological know-how have expanded the opportunity and variety of manufacturing to a massive extent. With the upward jab in the quantum of demands, extra complicated and state-of-the- art systems are being added day by day to meet the needs of the people. A machine is expected to function flawlessly over a long period. If it features for the supposed time, it is said to be reliable. However, failure of the tool or the machinery may take place at any instance which may fall in the context beyond human control; nonethe- less, the buyers assume best tiers of talent and perfection in the manufactured tools that are strongly implying “reliability.” The reliability of a device is the likelihood that it will perform the function of making merchandise on a nonstop groundwork and with suited carrier first rate and price effectiveness. Effective reliability analysis is a vital thing in the operation and planning of a system. This ever-increasing focus on reliability has resulted in more than one repercussion, which includes develop- ment in science to produce first-class products/machinery and to make the technique of manufacturing and production a costly affair. Reetu Malhotra, Chitkara University Institute of Engineering and Technology, Chitkara University, Punjab, India, reetu.malhotra@chitkarauniversity.edu.in https://doi.org/10.1515/9783110617375-006