Dear Colleagues,

Today's society is in a so-called digital transformation. The increasing degree of digitization has become a much-discussed phenomenon in society, politics, the media, and business. The economy is facing the so-called digital business transformation. This describes the transition phase from the third to the fourth industrial age, Industry 4.0, and is referred to as the digital age. The intelligent networking of machines, systems, and people plays a key role in this. Today, the digital twin is increasingly used in Germany as part of the IT infrastructure for Industry 4.0. There, it is used to describe and virtually simulate existing systems (e.g., production plants) based on the data generated. Supplemented by a simulation model, the digital twin can then be used to analyze the underlying system and, if necessary, to make predictions about its behavior. This, in turn, supports business-relevant decisions, for example in relation to the status and productivity of the plant. The increasing use of digital twins in the context of Industry 4.0 is mainly due to improvements in the underlying technologies (such as the Internet of Things, Big Data, machine learning, data security, etc.).

The concept of the digital twin is currently very prominent in various debates and is interpreted very differently in terms of its relevance for smart cities. However, it offers great potential to create added value on the basis of classic, established approaches such as geoportals, data platforms, etc., which are already widespread in today's smart cities. The application scenarios in the city are very diverse. The basis is the combination of data from different sources. If these are available with a uniform interface, this already has its own advantage. Digital twins enable simulations and planning before they are implemented, in particular to identify problems that may arise before they become reality.

Current studies by various authors on digital twins in the smart city have mainly only dealt with technical, organizational, and social issues, but it is noticeable that there is still no uniform understanding of the use and potential of the term digital twin in the science and practice context of a smart city. The digital twin is often misleadingly used for various forms of intelligent solutions without formally taking into account the criteria of a real digital twin.

In order to sensibly classify the currently realized potential and still open challenges around digital twins for urban initiatives, we would like to invite your contribution to our Special Issue, using practical examples to show which development possibilities the integration of a digital twin in smart cities entails and which areas of application are currently are implemented particularly frequently. As simulation has been used for planning and gaining knowledge about systems for several years, and simulation models are therefore already available in many companies, the question arises as to how these simulation models can also be used as part of the digital twin in the context of smart cities.

Dr. Otmane Azeroual
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Smart Cities is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• digital twin
• smart city
• industry 4.0
• internet of things
• big data
• machine learning
• data security
• simulations