Advances in speech recognition have led to a proliferation of dialogue systems that have found usefulness in real life situations. These systems provide cost-effective and wide scale access to services, and can be used to bridge the digital gap between the developed world and the developing world. They can also be implemented in different languages of the world to allow the low literates access to services. This special issue solicits for contributions in the area of successful applications of dialogue systems in different areas of human endeavours and the lessons learnt.

The Internet is becoming ubiquitous with the continuous advance of wireless mobile communication devices and systems. The massive network of wired/wireless physical objects/things/sensors/devices provides a worldwide information infrastructure that is changing the lives of humanity. However, modern ubiquitous communication and information systems pose a great challenge to security and energy efficiency in many aspects, where a plenty of factors need to be taken into consideration with regards to next-generation trustworthy and secure computing and communications. Among many important perspectives, examples include data security and authentication, privacy, access control, covert communication countermeasures, resource efficiency, energy-aware computing and communication, scalability and mobility. This special issue solicits high-quality original research results on energy efficient and trustworthy communication systems that manifest state of the art in various ubiquitous application scenarios.

Optimization is the task of finding one or more solutions which correspond to minimizing (or maximizing) one or more specified objectives.Multi-disciplinary design optimization (MDO) is a field of engineering that uses optimization methods to solve design problems incorporating a number of disciplines.In recent years, the growth of computational capabilities has extendedthe application of MDO methods and optimizations techniques in the design of complex real-world engineering problems.MDO methods and optimization techniques has proved to be useful tools in engineering design problems. In this regard, the aim of this special issue is to concentrate on the application of Multidisciplinary Design Optimization techniques and optimization methods in the design of complex systems.