# Internet of Things: A Scientometric Review
## 4 Research Topics
### Applications  
There are several application fields related to IoT research and development. In this section, the authors' keywords were analyzed to find the top specified applications. Figure 5 shows the trend of these applications in documents per year. Furthermore, Figure 5a presents the applications that start with the word \"smart\", and Figure 5b those that do not. In the data set, 1052 documents were found for applications that start with \"smart\". Smart city is the top one in this list, with 413 documents, and a sigmoid growth in exponential phase, 95% more publications in 2016 vs. 2015. [PERSON] has the most number of documents in this field with 12 publications. His most cited document [83] refers to Smart and Connected Communities as a concept that is evolving from Smart cities. The leading country in this application is Italy with 50 publications, and the most important correlated topics are Big data [84; 85; 86], Cloud computing [87; 88], and Smart  
Figure 4: Internet of Things top authors’ keywords documents published per year, excluding the keywords: Internet of Things, IoT, Internet of Things (IoT), and The Internet of Things, for the period 2006 to 2016. Figure 5: Internet of Things top applications based authors’ keywords in documents per year, for the period 2006 to 2016. (**a**) applications that start with “smart” (**b**) applications that do not start with “smart”. grid [89; 90]. Similarly, Smart home has a linear growth, with 230 documents, and 111 in the last year, with China as the leading country. The most important related topics for Smart home are security [91; 92; 93], ZigBee [94; 95; 96], and activity recognition [97; 98; 99]. In contrast, smart grid is a topic that has not demonstrated continuous growth. In 2012-2013, the documents published per year decreased from 21 to 13, and in 2015-2016 from 56 to 55. Nevertheless, an overall 194 documents were registered on this topic, with China as the leading country. The term smart grid refers to \"a next generation power grid that uses two-way flows of electricity and information to create a widely distributed automated energy delivery network\" [100]. Within IoT, the research on smart grids are related to security [101; 102; 103], cloud computing [104; 105], and privacy [103; 106; 107]. According to [PERSON], \"Cyber-Physical Systems (CPS)s are physical, biological and engineered systems whose operations are monitored, coordinated, controlled and integrated by a computing and communication core\" [108]. Publications of this topic related to IoT have a sigmoid growth in exponential phase, with 182 publications in 2016, noting United States as the leading country with 34 documents. The most important related topics are: Industry 4.0 [109; 110; 111; 112], big data [113; 114; 115], and security [116; 117; 118]. Next, Healthcare and E-Health related to IoT exhibited a sigmoid growth in a transitional phase, with a total of 180 documents, and India as the leading country with 20 publications. Different IoT technologies are applied in this area such as sensors [119], RFID [120; 121; 122; 123], 6 LoWPAN [124; 125], and wearables [126; 127]. The third most growth topic was energy efficiency with 154 documents, and China and Italy as leading countries with 18 and 17 publications, respectively. Energy efficiency as an application for IoT is related in this data set with the following topics: smart buildings [128; 129; 130], energy harvesting [131; 132; 133], and RFID [134; 135]. Social networks (or Social media) is another application for IoT, with 117 documents, and Italy as the leading country with 23 publications. Among the top related topics in this field are trust management [136; 137; 138] and recommendation systems [139; 140]. Education, Learning, E-Learning, and mobile learning is the fifth top application in this list, with 93 publications and the United Kingdom as the leading country with 12 documents.