Introduction

Each year, billions of dollars are spent globally to develop, manufacture, operate, and maintain transportation systems such as aircraft, ships, trains, and motor vehicles. These systems carry billions of tons of goods and billions of passengers annually from one point to another point throughout the world. For example, as per the International Air Transportation Association (IATA), the world’s 900 airlines with around 22,000 aircraft carry over 1.6 billion passengers for business and leisure travel each year, and over 40% of world trade of goods is carried by air [1-3].