The editors of <i>Challenges</i> would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2013. [...]

The jsGraph library is a versatile javascript library that allows advanced charting to be rendered interactively in web browsers without relying on server-side image processing. jsGraph is released under the MIT license and is free of charge. While being highly customizable through an intuitive...

Planners, designers, citizens, and governmental agencies are interested in creating environments that are sustainable and fulfill a wide range of economic, ecological, aesthetic, functional, and cultural expectations for stakeholders. There are numerous approaches and proposals to create such...

Pingtung County, located in the southernmost part of Taiwan, has been selected as one of the Smarter Cities Challenge by the International Business Machines (IBM) in 2013 due to its innovative promotion for renewable energy exploitation in recent years. In this regard, the objective of this...

There is an emerging trend in evaluating industrial activities using principles of industrial ecology because of the emphasis on sustainability initiatives by major process industries. Attention has also been targeted at developing planned industrial ecosystems (IEs) across the globe. We point...

The capability to present electronic media that can preserve information is highly restricted to few decades (e.g., a lifetime of DVD media does not exceed 100 years), and therefore the question of how to preserve documents for more than thousands or millions of years presents a challenging...

Solar-to-electricity energy conversion and large scale electricity storage technologies are key to achieve a sustainable development of society. For energy conversion, photoelectrochemical solar cells were proposed as an economic alternative to the conventional Si-based technology. For energy...