Design and Analysis of a Mechanical Driveline with Generator for an Atmospheric Energy Harvester

The advent of renewable energy as a primary power source for microelectronic devices has motivated research within the energy harvesting community over the past decade. Compact, self-contained, portable energy harvesters can be applied to wireless sensor networks, Internet of Things (IoT) smart appliances, and a multitude of standalone equipment; replacing batteries and improving the operational life of such systems. Atmospheric changes influenced by cyclical temporal variations offer an abundance of harvestable thermal energy. However, the low conversion efficiency of a common thermoelectric device does not tend to be practical for microcircuit operations. One solution may lie in a novel electromechanical power transformer integrated with a thermodynamic based phase change material to create a temperature/pressure energy harvester. The performance of the proposed harvester will be investigated using both numerical and experimental techniques to offer insight into its functionality and power generation capabilities. The atmospheric energy harvester consists of a ethyl chloride filled mechanical bellows attached to an end plate and constrained by a stiff spring and four guide rails that allow translational motion. The electromechanical power transformer consists of a compound gear train driven by the bellows end plate, a ratchet-controlled coil spring to store energy, and a DC micro generator. Nonlinear mathematical models have been developed for this multi-domain dynamic system using fundamental engineering principles. The initial analyses predicted 9.6 mW electric power generation over a 24 hour period for ±1°C temperature variations about a nominal 22°C temperature. Transfer functions were identified from the lumped parameter models and the transient behavior of the coupled thermal-electromechanical system has been studied. A prototype experimental system was fabricated and laboratory tested to study the overall performance and validate the mathematical models for the integrated energy harvester system. The experimental results agree with the numerical analyses in behavioral characteristics. Further, the power generation capacity of 30 mW for a representative electrical resistance load and emulated rack input which correspond to 50 cyclic bidirectional temperature variations (~175 hours of field operation) validated the simulation models. This research study provides insight into the challenges of designing an electromechanical power transformer to complement an atmospheric energy harvester system. The mathematical models estimated the behavior and performance of the integrated harvester system and establishes a foundation for future optimization studies. The opportunity to power microelectronic devices in the milliwatt range for burst electric operation or with the use of supercapacitors/batteries enables global remote operation of smart appliances. This system can assist in reducing/eliminating the need for batteries and improving the operational life of a variety of autonomous equipment. Future research areas have been identified to improve the overall system capabilities and implement the harvester device for real-world applications

Vibration Energy Harvesting for Wireless Sensors

Kinetic energy harvesters are a viable means of supplying low-power autonomous electronic systems for the remote sensing of operations. In this Special Issue, through twelve diverse contributions, some of the contemporary challenges, solutions and insights around the outlined issues are captured describing a variety of energy harvesting sources, as well as the need to create numerical and experimental evidence based around them. The breadth and interdisciplinarity of the sector are clearly observed, providing the basis for the development of new sensors, methods of measurement, and importantly, for their potential applications in a wide range of technical sectors

Agricultural Structures and Mechanization

In our globalized world, the need to produce quality and safe food has increased exponentially in recent decades to meet the growing demands of the world population. This expectation is being met by acting at multiple levels, but mainly through the introduction of new technologies in the agricultural and agri-food sectors. In this context, agricultural, livestock, agro-industrial buildings, and agrarian infrastructure are being built on the basis of a sophisticated design that integrates environmental, landscape, and occupational safety, new construction materials, new facilities, and mechanization with state-of-the-art automatic systems, using calculation models and computer programs. It is necessary to promote research and dissemination of results in the field of mechanization and agricultural structures, specifically with regard to farm building and rural landscape, land and water use and environment, power and machinery, information systems and precision farming, processing and post-harvest technology and logistics, energy and non-food production technology, systems engineering and management, and fruit and vegetable cultivation systems. This Special Issue focuses on the role that mechanization and agricultural structures play in the production of high-quality food and continuously over time. For this reason, it publishes highly interdisciplinary quality studies from disparate research fields including agriculture, engineering design, calculation and modeling, landscaping, environmentalism, and even ergonomics and occupational risk prevention

CHARACTERIZATION AND ENHANCEMENT OF SENSING PROPERTIES OF PIEZOELECTRIC MATERIALS WITH APPLICATIONS TO VIBRATION SUPPRESSION

This thesis undertakes the study of piezoelectric properties of polymer-based fabric and film sensors. An enhancement in piezoelectric properties of such sensors, as noted through earlier work, is observed with increasing weight ratios of nanomaterials dispersed in the polymer matrix. A comprehensive mathematical model using cantilever beams is developed to analyze this enhancement both qualitatively and quantitatively. An experimental setup is also developed to implement the proposed real time signal processing necessary to collect required data towards the characterization. In order to distinguish piezoelectric materials from other materials, study of the frequency response of developed fabric sensors to periodic chirp type actuation signals, is also established. Linear Euler-Bernoulli beam theory is used, to model piezoelectric actuation of cantilever beams. The theory has been extended to integrate piezoelectric sensing with the governing equations of motion to obtain a numerical solution to the governing partial differential equation of motion. All equations are derived using a distributed-parameters model applying the extended Hamilton Principle. Results obtained are compared to base values from literature for known materials. Piezoelectric materials are also known to possess bi-stiffness properties, having a higher modulus of elasticity in their open circuit configuration as compared to that in their short circuit configuration. Through research, it has been observed that the weight ratio of dispersed nanomaterials does not affect the piezoelectric properties alone but also has an effect on the mechanical properties and beyond a threshold, established for every polymer analyzed, the increase in the tensile properties of the fabric developed cannot be ignored. This study is extended to analyze the enhancement in the difference between the two moduli of elasticity for the fabric sensors in their respective configurations. The bi-stiffness elements can be used effectively to suppress vibrations implementing a semi-active vibration damping method known as `Switched Stiffness\u27. This concept is studied in regard to continuous systems, and the underlying principle of switching between two configurations is mathematically modeled. The developed control law for vibration suppression is then integrated using non-contact type measurement of tip deflection to suppress vibrations induced in cantilever beams, using the fabric sensors developed at Clemson University. The damping characteristics have been analyzed to study the enhancement in the difference between the higher and lower stiffness values and qualitative conclusions are drawn. Using the mathematical modeling developed to implement the `Switched Stiffness\u27 concept, a novel method to measure the coupling coefficient, k31, a characteristic constant for piezoelectric materials, is established and validated. The results of this measurement are used to decouple the piezoelectric properties from the mechanical properties and a generalized framework to completely characterize piezoelectric materials towards other constants has been proposed

Harvesting energy from non-ideal vibrations

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (p. 147-152).Energy harvesting has drawn significant interest for its potential to power autonomous low-power applications. Vibration energy harvesting is particularly well suited to industrial condition sensing, environmental monitoring and household environments where low-level vibrations are commonly found. While significant progress has been made in making vibration harvesters more efficient, most designs are still based on a single constant vibration frequency. However, most vibration sources do not have a constant frequency nor a single harmonic. Therefore, the inability to deal with non-ideal vibration sources has become a major technological obstacle for vibration energy harvesters to be widely applicable. To advance the state of vibration energy harvesting, this thesis presents a design methodology that is capable of dealing with two major non-ideal vibration characteristics: single harmonic frequency shifting and multi-frequency/broadband excitation. This methodology includes a broad-band impedance matching theory and a power electronics architecture to implement that theory. The generalized impedance matching theory extends the well known single frequency impedance matching model to a multi-frequency impedance matching model. By connecting LC tank circuits to the harvester output, additional resonant frequencies are created thereby enabling the energy harvesting system to effectively harvest energy from multi-harmonic vibration sources. However, the required inductors in the LC tank circuits are often too large (>10 H) to be implemented with discrete components. The power electronics proposed here addresses this issue by synthesizing the tank circuits with a power factor correction (PFC) circuit. This circuit mainly consists of an H-bridge, which contains four FETs, and a control loop that turns the FETs on and off at the right time such that the load voltage and current display the characteristics of the multiple tank circuits. By using this proposed power electronics, we demonstrate dual-frequency energy harvesting from a single mechanically resonant harvester. Simulation and experimental results match well and demonstrate that the proposed power electronics is capable of implementing higher order multi-resonant energy harvesting systems. In conclusion, this thesis presents both a theoretical foundation and a power electronics architecture that enables simultaneous effective multi-frequency energy harvesting with a single mechanically resonant harvester. The tunability of the power electronics also provides the possibility of dynamic real-time tuning which is useful to track non-stationary vibration sources.by Samuel C. Chang.Ph.D

Piezoelectric Energy Harvesting: Enhancing Power Output by Device Optimisation and Circuit Techniques

Energy harvesting; that is, harvesting small amounts of energy from environmental sources such as solar, air flow or vibrations using small-scale (≈1cm 3 ) devices, offers the prospect of powering portable electronic devices such as GPS receivers and mobile phones, and sensing devices used in remote applications: wireless sensor nodes, without the use of batteries. Numerous studies have shown that power densities of energy harvesting devices can be hundreds of µW; however the literature also reveals that power requirements of many electronic devices are in the mW range. Therefore, a key challenge for the successful deployment of energy harvesting technology remains, in many cases, the provision of adequate power. This thesis aims to address this challenge by investigating two methods of enhancing the power output of a piezoelectric-based vibration energy harvesting device. Cont/d

DETECTION AND REMOVAL OF DUST PARTICLES IN PIPELINES USING 3-D MEMS

Currently, the detection of dust particles is realized through manual sampling. Thus it is desirable to develop an automated online technique. Generally, industries run with the help of pipelines through which liquid can flow. The main aim of the work is to detect the dust particles which are present inside the pipeline when liquid is flowing through it. Distributed Acoustic Sensing (DAS) is a recent addition to the pipeline security world. Opta sense system is designed to prevent the damage in pipeline by providing the advance warning to the concern department and make them alert. The dust particles are detected by using MEMS, which can sense in three axis (Heat, Vibration, Movement). It is identified by the IR sensor. The approach can also be simulated by using MATLAB