Slim Naifar

Bio: Slim Naifar is an academic researcher from Chemnitz University of Technology. The author has contributed to research in topics: Energy harvesting & Vibration. The author has an hindex of 11, co-authored 34 publications receiving 290 citations. Previous affiliations of Slim Naifar include University of Sfax.

Energy-Aware System Design for Autonomous Wireless Sensor Nodes: A Comprehensive Review.

Abstract: Nowadays, wireless sensor networks are becoming increasingly important in several sectors including industry, transportation, environment and medicine. This trend is reinforced by the spread of Internet of Things (IoT) technologies in almost all sectors. Autonomous energy supply is thereby an essential aspect as it decides the flexible positioning and easy maintenance, which are decisive for the acceptance of this technology, its wide use and sustainability. Significant improvements made in the last years have shown interesting possibilities for realizing energy-aware wireless sensor nodes (WSNs) by designing manifold and highly efficient energy converters and reducing energy consumption of hardware, software and communication protocols. Using only a few of these techniques or focusing on only one aspect is not sufficient to realize practicable and market relevant solutions. This paper therefore provides a comprehensive review on system design for battery-free and energy-aware WSN, making use of ambient energy or wireless energy transmission. It addresses energy supply strategies and gives a deep insight in energy management methods as well as possibilities for energy saving on node and network level. The aim therefore is to provide deep insight into system design and increase awareness of suitable techniques for realizing battery-free and energy-aware wireless sensor nodes.

Electromagnetic Vibration Energy Harvesting for Railway Applications

Abstract: Safe localization of trains via GPS and wireless sensors is essential for railway traffic supervision Especially for freight trains and because normally no power source is available on the wagons, special solutions for energy supply have to be developed based on energy harvesting techniques Since vibration is available in this case, it provides an interesting source of energy Nevertheless, in order to have an efficient design of the harvesting system, the existing vibration needs to be investigated In this paper, we focus on the characterization of vibration parameters in railway application We propose an electromagnetic vibration converter especially developed to this application Vibration profiles from a train traveling between two German cities were measured using a data acquisition system installed on the train’s wagon Results show that the measured profiles present multiple frequency signals in the range of 10 to 50 Hz and an acceleration of up to 2 g A prototype for a vibration converter is designed taking into account the real vibration parameters, robustness and integrability requirements It is based on a moving coil attached to a mechanical spring For the experimental emulation of the train vibrations, a shaker is used as an external artificial vibration source controlled by a laser sensor in feedback A maximum voltage of 17 V peak to peak which corresponds to a maximum of 10 mW output power where the applied excitation frequency is close to the resonant frequency of the converter which corresponds to 27 Hz

Next Generation Wireless Energy Aware Sensors for Internet of Things: A Review

Abstract: In the internet of things context, the use of Wireless Sensor Networks (WSN) becomes extensive and the aspect of energy supply becomes more and more essential. Flexible positioning and easy maintenance become a key aspect for the acceptance of this technology. In this paper, we focus on novel trends for supplying WSN from ambient energy and by wireless energy transmission. The improvements made in the last years have shown that it is possible to significantly improve energy efficiency by suitable converters and to reduce energy consumption of sensor nodes, so that the use of these emerging technologies becomes increasingly realistic and practicable. We report about possibilities for improving energy income by combination of converters within hybrid solutions. Different techniques for enhancing efficiency of energy converters and reducing energy consumption on node and network level are described.

Design of a vibration energy harvester by twin lateral magnetoelectric transducers

Abstract: Scavenging energy from vibration is important for several fields of science and technology. A big challenge thereby is to realize miniaturized solutions able to deliver sufficient energy for supply a wireless sensor node. A magnetoelectric (ME) vibration energy harvester based on a twin laminate composite of magnetostrictive and piezoelectric materials was designed, developed and tested. The vibration converter uses simultaneously two transversely polarized PZT plates and two longitudinally magnetized Terfenol-D plates placed within a magnetic field. The presented design can make the best use of the magnetic field produced by the magnetic circuit. The repulsion force is generated by two magnetic springs leading to less friction than a classical mechanical spring. The implementation issues of the harvester have been subjected to several experimental studies using an adjustable artificial excitation source. The results show that doubling the amplitude of vibration leads to an energy output which is four times more. The comparison with a single transducer shows that the twin lateral converter reaches especially at resonance frequency the one and half energy outcome.

Energy Harvesting Technologies for Achieving Self-Powered Wireless Sensor Networks in Machine Condition Monitoring: A Review.

Abstract: Condition monitoring can reduce machine breakdown losses, increase productivity and operation safety, and therefore deliver significant benefits to many industries. The emergence of wireless sensor networks (WSNs) with smart processing ability play an ever-growing role in online condition monitoring of machines. WSNs are cost-effective networking systems for machine condition monitoring. It avoids cable usage and eases system deployment in industry, which leads to significant savings. Powering the nodes is one of the major challenges for a true WSN system, especially when positioned at inaccessible or dangerous locations and in harsh environments. Promising energy harvesting technologies have attracted the attention of engineers because they convert microwatt or milliwatt level power from the environment to implement maintenance-free machine condition monitoring systems with WSNs. The motivation of this review is to investigate the energy sources, stimulate the application of energy harvesting based WSNs, and evaluate the improvement of energy harvesting systems for mechanical condition monitoring. This paper overviews the principles of a number of energy harvesting technologies applicable to industrial machines by investigating the power consumption of WSNs and the potential energy sources in mechanical systems. Many models or prototypes with different features are reviewed, especially in the mechanical field. Energy harvesting technologies are evaluated for further development according to the comparison of their advantages and disadvantages. Finally, a discussion of the challenges and potential future research of energy harvesting systems powering WSNs for machine condition monitoring is made.

Energy Harvesting Techniques for Internet of Things (IoT)

Abstract: The rapid growth of the Internet of Things (IoT) has accelerated strong interests in the development of low-power wireless sensors. Today, wireless sensors are integrated within IoT systems to gather information in a reliable and practical manner to monitor processes and control activities in areas such as transportation, energy, civil infrastructure, smart buildings, environment monitoring, healthcare, defense, manufacturing, and production. The long-term and self-sustainable operation of these IoT devices must be considered early on when they are designed and implemented. Traditionally, wireless sensors have often been powered by batteries, which, despite allowing low overall system costs, can negatively impact the lifespan and the performance of the entire network they are used in. Energy Harvesting (EH) technology is a promising environment-friendly solution that extends the lifetime of these sensors, and, in some cases completely replaces the use of battery power. In addition, energy harvesting offers economic and practical advantages through the optimal use of energy, and the provisioning of lower network maintenance costs. We review recent advances in energy harvesting techniques for IoT. We demonstrate two energy harvesting techniques using case studies. Finally, we discuss some future research challenges that must be addressed to enable the large-scale deployment of energy harvesting solutions for IoT environments.