{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,6]],"date-time":"2026-05-06T16:01:52Z","timestamp":1778083312336,"version":"3.51.4"},"reference-count":60,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2021,4,8]],"date-time":"2021-04-08T00:00:00Z","timestamp":1617840000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"FCT\/MCTES through national funds","award":["UIDB\/50008\/2020-UIDP\/50008\/2020"],"award-info":[{"award-number":["UIDB\/50008\/2020-UIDP\/50008\/2020"]}]},{"DOI":"10.13039\/501100000780","name":"European Commission","doi-asserted-by":"publisher","award":["UIDB\/50008\/2020-UIDP\/50008\/2020"],"award-info":[{"award-number":["UIDB\/50008\/2020-UIDP\/50008\/2020"]}],"id":[{"id":"10.13039\/501100000780","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Smart Cities"],"abstract":"<jats:p>The issue of how to power the deployed Internet of Things (IoT) nodes with ubiquitous and long lasting energy in order to ensure uninterruptible optimisation of smart cities is of utmost concern. This among other challenges has continued to gear efforts toward energy harvesting research. With the outbreak of COVID-19 pandemic and the lockdown that nearly paralysed activities of everyday living in many nations of the world, option of human remote interaction to enforce social distancing became imperative. Hence, the world is witnessing a renewed awareness of the importance of IoT devices, as integral components of smart city, especially for the essence of survival in the face of lockdown. Energy harvesting is a possible solution that could enable IoT nodes to scavenge self-sustaining energy from environmental ambient sources. In this paper, we have reviewed most sources within city that energy could be harvested from, as reported by researchers in literature. In addition, we have submitted that energy sources can be application specific, such that, since there are many free sources in the city as presented in this review, energy should be scavenged within close proximity of need for various IoT devices or wireless sensor networks (WSNs), for smart city automation.<\/jats:p>","DOI":"10.3390\/smartcities4020025","type":"journal-article","created":{"date-parts":[[2021,4,8]],"date-time":"2021-04-08T21:27:44Z","timestamp":1617917264000},"page":"476-498","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":68,"title":["Energy Harvesting Mechanisms in a Smart City\u2014A Review"],"prefix":"10.3390","volume":"4","author":[{"given":"Ajibike Eunice","family":"Akin-Ponnle","sequence":"first","affiliation":[{"name":"Departamento de Electronica Telecomunica\u00e7\u00f5es e Inform\u00e1tica, DETI, Universidade de Aveiro, Campus Universit\u00e1rio de Santiago, 3810-193 Aveiro, Portugal"},{"name":"Instituto de Telecommunica\u00e7\u00f5es, Universidade de Aveiro, 3810-193 Aveiro, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7402-2099","authenticated-orcid":false,"given":"Nuno Borges","family":"Carvalho","sequence":"additional","affiliation":[{"name":"Departamento de Electronica Telecomunica\u00e7\u00f5es e Inform\u00e1tica, DETI, Universidade de Aveiro, Campus Universit\u00e1rio de Santiago, 3810-193 Aveiro, Portugal"},{"name":"Instituto de Telecommunica\u00e7\u00f5es, Universidade de Aveiro, 3810-193 Aveiro, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2021,4,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"94533","DOI":"10.1109\/ACCESS.2019.2928523","article-title":"Towards a Green and Self-Powered Internet of Things Using Piezoelectric Energy Harvesting","volume":"7","author":"Shirvanimoghaddam","year":"2019","journal-title":"IEEE Access"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"850","DOI":"10.1109\/TIE.2009.2024652","article-title":"Kinetic Energy Harvesting using Piezoelectric and Electromagnetic Technologies- State of the Art","volume":"57","author":"Khaligh","year":"2010","journal-title":"IEEE Trans. Ind. Electron."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"4495","DOI":"10.1109\/TMAG.2012.2201452","article-title":"A Vibration-Based Hybrid Energy Harvester for Wireless Sensor Systems","volume":"48","author":"Sang","year":"2012","journal-title":"IEEE Trans. Magn."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"196","DOI":"10.1109\/JIOT.2014.2301819","article-title":"A Novel Deployment Scheme for Green Internet of Things","volume":"1","author":"Huang","year":"2014","journal-title":"IEEE Internet Things J."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"129","DOI":"10.1016\/j.techfore.2018.10.029","article-title":"Municipalities\u2019 understanding of the Smart City concept: An exploratory analysis in Belgium","volume":"142","author":"Desdemoustier","year":"2019","journal-title":"Technol. Forecast. Soc. Chang."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"60376","DOI":"10.1109\/ACCESS.2019.2913784","article-title":"Formal Analysis of Human-Assisted Smart City Emergency Services","volume":"7","author":"Mohammad","year":"2019","journal-title":"IEEE Access"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"102023","DOI":"10.1016\/j.scs.2020.102023","article-title":"Security and the Smart City: A Systematic Review","volume":"55","author":"Laufs","year":"2020","journal-title":"Sustain. Cities Soc."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Angelidou, M., Psaltoglou, A., Komninos, N., Kakderi, C., Tsarchopoulos, P., and Panori, A. (2018). Enhancing Sustainable Urban Development through Smart City Applications. J. Sci. Technol. Policy Manag.","DOI":"10.1108\/JSTPM-05-2017-0016"},{"key":"ref_9","first-page":"57","article-title":"Role of Internet of Things (IOT) in Pandemic Covid-19 Condition","volume":"10","author":"Chaudhari","year":"2020","journal-title":"Int. J. Eng. Res. Appl."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"153479","DOI":"10.1109\/ACCESS.2020.3018140","article-title":"A Comprehensive Survey of Enabling and Emerging Technologies for Social Distancing\u2014Part I: Fundamentals and Enabling Technologies","volume":"8","author":"Nguyen","year":"2020","journal-title":"IEEE Access"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"770","DOI":"10.1016\/j.egypro.2017.03.239","article-title":"A review on Internet of Things solutions for intelligent energy control in buildings for smart city applications","volume":"111","author":"Khajenasiri","year":"2017","journal-title":"Energy Procedia"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"121620","DOI":"10.1016\/j.jclepro.2020.121620","article-title":"Internet-of-things-based optimal smart city energy management considering shiftable loads and energy storage","volume":"264","author":"Bahramara","year":"2020","journal-title":"J. Clean. Prod."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"56577","DOI":"10.1109\/ACCESS.2019.2907793","article-title":"Application Specific Internet of Things (ASIoTs):Taxonomy, Applications, Use Case and Future Directions","volume":"7","author":"Ang","year":"2019","journal-title":"IEEE Access"},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Chen, S.-M., and Hu, J.-H. (2011, January 9\u201315). Experimental Study of a Hybrid Vibration Energy Harvesting Mechanism. Proceedings of the Symposium on Piezoelectricity, Acoustic Waves and Device Applications (SPAWDA), Shenzhen, China.","DOI":"10.1109\/SPAWDA.2011.6167190"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Shahhaidar, E., Boric-Lubecke, O., Ghorbani, R., and Wolfe, M. (2011, January 24\u201328). Electromagnetic Generator as Respiratory Effort Energy Harvester. Proceedings of the IEEE Power and Energy Conference at Illinious, Detroit, MI, USA.","DOI":"10.1109\/PECI.2011.5740494"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"399","DOI":"10.1109\/JBHI.2014.2326597","article-title":"Electromagnetic Respiratory Effort Harvester: Human Testing and Metabolic Cost Analysis","volume":"19","author":"Shahhaidar","year":"2015","journal-title":"IEEE J. Biomed. Health Inform."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"4376","DOI":"10.1109\/TMAG.2009.2024769","article-title":"Feasibility Study on a New Energy Harvesting Electromagnetic Device using Aerodynamic Instability","volume":"45","author":"Jung","year":"2009","journal-title":"IEEE Trans. Magn."},{"key":"ref_18","first-page":"218","article-title":"Vertical Vibration based Electret-Cantilever Method of Micro-Power Generation for Energy Harvesting","volume":"3","author":"Ponnle","year":"2014","journal-title":"Int. J. Eng. Innov. Technol. (IJEIT)"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"516","DOI":"10.1109\/JMEMS.2015.2413811","article-title":"Electrostatic Energy Harvester Using Magnetically Actuated Liquid Dielectric Layers","volume":"24","author":"Kim","year":"2015","journal-title":"J. Microelectromech. Syst."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1454","DOI":"10.1109\/JMEMS.2014.2315199","article-title":"An Omnidirectional MEMS Ultrasonic Energy Harvester for Implanted Devices","volume":"23","author":"Flower","year":"2014","journal-title":"J. Microelectromech. Syst."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"5639","DOI":"10.1109\/TIE.2012.2230891","article-title":"Low-Power ASIC for Microwatt Electrostatic Energy Harvesters","volume":"60","author":"Kempitiya","year":"2013","journal-title":"IEEE Trans. Ind. Electron."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1421","DOI":"10.1109\/LED.2013.2282815","article-title":"Design and Characterization of a 2-DOF MEMS Ultrasonic Energy Harvester with Triangular Electrostatic Electrodes","volume":"34","author":"Fowler","year":"2013","journal-title":"IEEE Electron Device Lett."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Ahmed, S., and Kakkar, V. (2017). An Electret-Based Angular Electrostatic Energy Harvester for Battery-Less Cardiac and Neural Implants. IEEE Access, 19631\u201319643.","DOI":"10.1109\/ACCESS.2017.2739205"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"483","DOI":"10.1109\/JSSC.2009.2038431","article-title":"A 0.7-\u00b5m BiCMOS Electrostatic Energy-Harvesting System IC","volume":"45","author":"Torres","year":"2010","journal-title":"IEEE J. Solid State Circuits"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1551","DOI":"10.1109\/TCSI.2011.2142731","article-title":"Harvesting Ambient Kinetic Energy with Switched-Inductor Converters","volume":"58","author":"Kwon","year":"2011","journal-title":"IEEE Trans. Circuits Syst. I Regul. Pap."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"10308","DOI":"10.1109\/TPEL.2017.2775961","article-title":"Design Optimization of an Energy Harvesting Platform for Self-Powered Wireless Devices in Monitoring of AC Power Lines","volume":"33","author":"Abasian","year":"2018","journal-title":"IEEE Trans. Power Electron."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"813","DOI":"10.1109\/TIE.2009.2028360","article-title":"Energy Harvesting from Piezoelectric Materials Fully Integrated in Footwear","volume":"57","author":"Rocha","year":"2010","journal-title":"IEEE Trans. Ind. Electron."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Balguvhar, S., and Bhalla, S. (2018, January 24\u201326). Green Energy Harvesting Using Piezoelectric Materials from Bridge Vibrations. Proceedings of the IEEE 2nd International Conference on Green Energy and Applications, Singapore.","DOI":"10.1109\/ICGEA.2018.8356282"},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Kwon, Y., Lee, J., Choi, M., and Lee, J. (2017, January 18\u201321). A study on the P.H.A.S (Piezoelectric energy Harvesting based Access control System) using motor vibration. Proceedings of the IEEE 17th International Conference on Control, Automation and Systems (ICCAS 2017), Ramada Plaza, Jeju, Korea.","DOI":"10.23919\/ICCAS.2017.8204214"},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Panthongsy, P., Isarakorn, D., Sudhawiyangkul, T., and Nundrakwang, S. (2015, January 24\u201327). Piezoelectric Energy Harvesting from Machine Vibrations for Wireless Sensor System. Proceedings of the 12th International Conference on Electrical Engineering\/Electronics, Computer, Telecommunications and Information Technology (ECTI-CON), Hua Hin, Thailand.","DOI":"10.1109\/ECTICon.2015.7207051"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1787","DOI":"10.1109\/TMECH.2015.2459014","article-title":"Toward Harvesting Vibration Energy from Multiple Directions by a Nonlinear Compressive-Mode Piezoelectric Transducer","volume":"21","author":"Yang","year":"2016","journal-title":"IEEE\/ASME Trans. Mechatronics"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1116","DOI":"10.1109\/TIE.2012.2187413","article-title":"Flow Energy Harvesting Using Piezoelectric Cantilevers with Cylindrical Extension","volume":"60","author":"Gao","year":"2013","journal-title":"IEEE Trans. Ind. Electron."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"151449","DOI":"10.1109\/ACCESS.2019.2948085","article-title":"Design of a New Piezoelectric Energy Harvesting Handrail with Vibration and Force Excitations","volume":"7","author":"Li","year":"2019","journal-title":"IEEE Access"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"742","DOI":"10.1109\/JMEMS.2014.2349794","article-title":"Harvesting Energy from a Rotating Gear Using an AFM-Like MEMS Piezoelectric Frequency Up-Converting Energy Harvester","volume":"24","author":"Janphuang","year":"2015","journal-title":"J. Microelectromech. Syst."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"1100","DOI":"10.1109\/JMEMS.2019.2942291","article-title":"T-Shaped Piezoelectric Structure for High-Performance MEMS Vibration Energy Harvesting","volume":"28","author":"Nabavi","year":"2019","journal-title":"J. Microelectromech. Syst."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"698","DOI":"10.1109\/TUFFC.2011.1862","article-title":"A Flex-Compressive-Mode Piezoelectric Transducer for Mechanical Vibration\/Strain Energy Harvesting","volume":"58","author":"Li","year":"2011","journal-title":"IEEE Trans. Ultrason. Ferroelectr. Freq. Control"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"1041","DOI":"10.1016\/j.rser.2015.11.010","article-title":"Energy harvesting in wireless sensor networks: A comprehensive review","volume":"55","author":"Shaikh","year":"2016","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1109\/MSSC.2010.936667","article-title":"Energy harvesting for autonomous wireless sensor networks","volume":"2","author":"Vuller","year":"2010","journal-title":"IEEE Solid State Circuits Mag."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"195","DOI":"10.1109\/SURV.2013.062613.00235","article-title":"Reincarnation in the ambiance: Devices and networks with energy harvesting","volume":"16","author":"Prasad","year":"2014","journal-title":"IEEE Commun. Surv. Tutor."},{"key":"ref_40","unstructured":"Rezaei, H.F., Kruger, A., and Just, C. (August, January 31). An Energy Harvesting Scheme for Underwater Sensor Applications. Proceedings of the International Conference on Electro\/Information Technology, Chicago, IL, USA."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"2346","DOI":"10.1109\/TIM.2018.2890187","article-title":"Self-Sustaining Acoustic Sensor with Programmable Pattern Recognition for Underwater Monitoring","volume":"68","author":"Mayer","year":"2019","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"4680","DOI":"10.1109\/JSEN.2019.2900427","article-title":"On the Lifetime of Compressive Sensing Based Energy Harvesting in Underwater Sensor Networks","volume":"19","author":"Erdem","year":"2019","journal-title":"IEEE Sensors J."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"4424","DOI":"10.1109\/TIE.2010.2102321","article-title":"Energy Harvesting from Hybrid Indoor Ambient Light and Thermal Energy Sources for Enhanced Performance of Wireless Sensor Nodes","volume":"58","author":"Tan","year":"2011","journal-title":"IEEE Trans. Ind. Electron."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"9021","DOI":"10.1109\/JSEN.2016.2616114","article-title":"High-Efficient Energy Harvester with Flexible Solar Panel for a Wearable Sensor Device","volume":"16","author":"Tran","year":"2016","journal-title":"IEEE Sens. J."},{"key":"ref_45","doi-asserted-by":"crossref","unstructured":"Meng, X., Li, X., Tsui, C.-Y., and Ki, W.-H. (2016, January 22\u201325). An Indoor Solar Energy Harvesting System using Dual Mode SIDO Converter with Fully Digital Time-Based MPPT. Proceedings of the IEEE International Symposium on Circuits and Systems (ISCAS), Montreal, QC, Canada.","DOI":"10.1109\/ISCAS.2016.7539057"},{"key":"ref_46","doi-asserted-by":"crossref","unstructured":"Vizzari, D., Chailleux, E., Lavaud, S., Gennesseaux, E., and Bouron, S. (2020). Fraction Factorial Design of a Novel Semi-Transparent Layer for Applications on Solar Roads. Infrastructures, 5.","DOI":"10.3390\/infrastructures5010005"},{"key":"ref_47","doi-asserted-by":"crossref","unstructured":"Brogan, Q., O\u2019Connor, T., and Ha, D.S. (2014, January 1\u20135). Solar and Thermal Energy Harvesting with a Wearable Jacket. Proceedings of the IEEE International Symposium on Circuits and Systems (ISCAS), Melbourne, Australia.","DOI":"10.1109\/ISCAS.2014.6865409"},{"key":"ref_48","first-page":"3530","article-title":"A Novel Thermoelectric Energy Harvester for Wireless Sensor Network Application","volume":"66","author":"Verma","year":"2019","journal-title":"IEEE Trans. Ind. Electron."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"35243","DOI":"10.1109\/ACCESS.2018.2851203","article-title":"Thermal Energy Harvesting WSNs Node for Temperature Monitoring in IIoT","volume":"6","author":"Hou","year":"2018","journal-title":"IEEE Access"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"1526","DOI":"10.1109\/TVT.2012.2188551","article-title":"Optimizing for efficiency or battery life in a battery\/supercapacitor electric vehicle","volume":"61","author":"Carter","year":"2012","journal-title":"IEEE Trans. Veh. Technol."},{"key":"ref_51","doi-asserted-by":"crossref","unstructured":"J\u00f6rke, P., Falkenberg, R., and Wietfeld, C. (2018, January 9\u201313). Power consumption analysis of nb-iot and emtc in challenging smart city environments. Proceedings of the 2018 IEEE Globecom Workshops (GC Wkshps9), Abu Dhabi, United Arab Emirates.","DOI":"10.1109\/GLOCOMW.2018.8644481"},{"key":"ref_52","unstructured":"Kalaagi, M., and Seetharamdoo, D. (April, January 31). Electromagnetic Energy Harvesting Systems in the Railway Environment: State of the Art and Proposal of a Novel Metamaterial Energy Harvester. Proceedings of the 13th European Conference on Antennas and Propagation (EuCAP), Krakow, Poland."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"1384","DOI":"10.1109\/COMST.2015.2497324","article-title":"Advances in Energy Harvesting Communications: Past, Present, and Future Challenges","volume":"18","author":"Ku","year":"2016","journal-title":"IEEE Commun. Surv. Tutor."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"19","DOI":"10.15546\/aeei-2017-0030","article-title":"Radio Frequency Energy Harvesting Sources","volume":"17","author":"Nechibvute","year":"2017","journal-title":"Acta Electrotech. Inform."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"34","DOI":"10.1017\/wpt.2015.22","article-title":"High Efficiency D-TV Energy Harvesting System for Low-Input Power","volume":"3","author":"Pinho","year":"2016","journal-title":"Wirel. Power Transf."},{"key":"ref_56","doi-asserted-by":"crossref","unstructured":"Salem, S., Fra\u0148a, K., Nov\u00e1, I., and Erhart, J. (2020, January 12\u201314). Acoustic Energy Harvesting Using Piezo-Electric Materials. Proceedings of the International Youth Conference on Radio Electronics, Electrical and Power Engineering (REPEE), Moscow, Russia.","DOI":"10.1109\/REEPE49198.2020.9059190"},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"2121","DOI":"10.1109\/TUFFC.2013.2802","article-title":"Enhanced Acoustoelectric Coupling in Acoustic Energy Harvester Using Dual Helmholtz Resonators","volume":"60","author":"Peng","year":"2013","journal-title":"IEEE Trans. Ultrason. Ferroelectr. Freq. Control"},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"33","DOI":"10.1109\/MITP.2018.2883047","article-title":"Understanding network requirements for smart city applications: Challenges and solutions","volume":"21","author":"Shoaib","year":"2019","journal-title":"IT Prof."},{"key":"ref_59","first-page":"79","article-title":"Energy harvesting on road pavements: State of the art","volume":"169","author":"Duarte","year":"2016","journal-title":"Proc. Inst. Civ. Eng. Energy"},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"784","DOI":"10.1109\/JIOT.2017.2747900","article-title":"From Micro to Macro IoT: Challenges and Solutions in the Integration of IEEE 802.15.4\/802.11 and Sub-GHz Technologies","volume":"5","author":"Davoli","year":"2018","journal-title":"IEEE Internet Things J."}],"container-title":["Smart Cities"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2624-6511\/4\/2\/25\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,13]],"date-time":"2025-10-13T13:34:24Z","timestamp":1760362464000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2624-6511\/4\/2\/25"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,4,8]]},"references-count":60,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2021,6]]}},"alternative-id":["smartcities4020025"],"URL":"https:\/\/doi.org\/10.3390\/smartcities4020025","relation":{},"ISSN":["2624-6511"],"issn-type":[{"value":"2624-6511","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,4,8]]}}}