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The large deployment of Internet of things (IoT) is actually enabling smart city projects and initiatives all over the world. Objects used in daily life are being equipped with electronic devices and protocol suites in order to make them interconnected and connected to the Internet. According to a recent Gartner study, 50 billion connected objects will be deployed in smart cities by 2020. These connected objects will make the authors' cities smart. However, they will also open up risks and privacy issues. As various smart city initiatives and projects have been launched in recent years, they have witnessed not only the expected benefits, but the risks introduced. They describe the current and future trends of smart city and IoT. They also discuss the interaction between smart cities and IoT and explain some of the drivers behind the evolution and development of IoT and smart city. Finally, they discuss some of the IoT weaknesses and how they can be addressed when used for smart cities.
Smart cities play an increasingly important role for the sustainable economic development of a determined area. Smart cities are considered a key element for generating wealth, knowledge and diversity, both economically and socially. A Smart City is the engine to reach the sustainability of its infrastructure and facilitate the sustainable development of its industry, buildings and citizens. The first goal to reach that sustainability is reduce the energy consumption and the levels of greenhouse gases (GHG). For that purpose, it is required scalability, extensibility and integration of new resources in order to reach a higher awareness about the energy consumption, distribution and generation, which allows a suitable modeling which can enable new countermeasure and action plans to mitigate the current excessive power consumption effects. Smart Cities should offer efficient support for global communications and access to the services and information. It is required to enable a homogenous and seamless machine to machine (M2M) communication in the different solutions and use cases. This work presents how to reach an interoperable Smart Lighting solution over the emerging M2M protocols such as CoAP built over REST architecture. This follows up the guidelines defined by the IP for Smart Objects Alliance (IPSO Alliance) in order to implement and interoperable semantic level for the street lighting, and describes the integration of the communications and logic over the existing street lighting infrastructure.
One of the major challenges at the moment is the improvement of the present street lighting system. These systems are considered outdated due the lack of communication capabilities, not allowing system feedback. This work aims to add communication capabilities to the systems already in use, through the integration of an IEEE 802.15.4 compatible transceiver to the photoelectric relay used to turn the HPS lamps on/off. This change will turn each device into a node of a large wireless network across the city.
One of the major challenges at the moment is the improvement of the present street lighting system. These systems are considered outdated due the lack of communication capabilities, not allowing system feedback. This work aims to add communication capabilities to the systems already in use, through the integration of a ZigBeetrade compatible transceiver to the photoelectric relay used to turn the HPS lamps on/off. This change will turn each device into a node of a large wireless network across the city.
This paper proposes a novel single-stage light-emitting diode (LED) driver for street-lighting applications with power factor corrections (PFC). The presented driver integrates a modified bridgeless PFC ac-dc converter with a half-bridge-type LLC dc-dc resonant converter into a single-stage conversion circuit topology. The proposed ac-dc resonant driver provides input current shaping, and it offers attributes of lowered switching losses to the soft-switching functions obtained on two power switches and two output-rectifier diodes. The proposed driver features cost-effectiveness, high circuit efficiency (>92%), high power factor (>0.99) and low input current total harmonics distortion (<;8%). A prototype driver is developed for supplying a 144-W-rated LED street-lighting module with utility-line input voltages ranging from 100 to 120 V, and experimental results demonstrate the functionalities of the proposed LED driver.
A study was conducted on the lighting operation and workspace occupancy patterns across numerous commercial buildings to better quantify the performance estimates of occupancy sensors across typical space types. By examining how occupants occupy their spaces and manually control their lighting, and comparing these baselines to modeled occupancy sensor control scenarios, energy and dollars savings potentials were investigated.
Electrolytic capacitor is the key component that limits the lifetime of LED driver. When an ac-dc LED driver with the function of power factor correction (PFC) outputs a pulsating current to drive LEDs, electrolytic capacitor is not required any longer. However, the pulsating current brings flicker with twice the line frequency. In this paper, the concept of flicker-free electrolytic capacitor-less ac-dc driver for LED lighting is proposed, which consists of an electrolytic capacitor-less PFC converter and a bidirectional buck/boost converter. The bidirectional buck/boost converter provides the path for the ac component in the pulsating current of the PFC converter to flow through, leaving a pure dc current to drive the LEDs without flicker. The voltage of the output filter capacitor of the bidirectional converter is intentionally designed to have large ripple, and thus the capacitance can be greatly reduced. Consequently, the output filter capacitor can adopt film capacitor instead of electrolytic capacitor. So the ac-dc LED driver has no flicker and has a long lifetime. A 48 V, 0.7 A output prototype is built and tested in the lab, and the experimental results are presented to verify the effectiveness of the flicker-free electrolytic capacitor-less ac-dc LED driver. Index Terms—Lighting emitting diode, power factor correction, flicker, driver.
Principi di progettazione ecologica, Maggioli S
- M L Palumbo
- Architettura Produttiva
M.L., Palumbo, Architettura Produttiva: Principi di progettazione ecologica, Maggioli S.p.A., ISBN 978.88.387.6849.8, January 2012.
A 40 v 10 w 93%-efficiency current-accuracyenhanced dimmable led driver with adaptive timing difference compensation for solid-state lighting applications
- D Park
- Z Liu
- H Lee
D. Park, Z. Liu, H. Lee, A 40 v 10 w 93%-efficiency current-accuracyenhanced dimmable led driver with adaptive timing difference compensation for solid-state lighting applications, IEEE Journal of Solid-State
Circuits 49 (8) (2014) 1848-1860.