Thermomechanical Energy Converters for Harvesting Thermal Energy:A Review

Thermal energy,i.e.,the electromagnetic energy in the infrared range that originates from the direct solar radiation,outgoing terrestrial radiation,waste heat from combustion of fuels,heat-emitting electrical devices,decay of radioactive isotopes,organic putrefaction and fermentation,human body heat,and so on,constitutes a huge energy flux circulating on the earth surface.However,most energy converters designed for the conversion of electromagnetic energy into electricity,such as photovoltaic cells,are mainly focused on using a narrow part of the solar energy lying in the visible spectrum,while thermomechanical engines that are fueled by heat in the broad energy range and then convert it into mechanical work or store it as mechanical deformation,are paid less attention.Although the efficiency of thermomechanical devices is relatively low,they can be applied to collect waste heat which otherwise contributes to negative climate changes.In this review,operational principles of thermomechanical energy converters and a description of basic devices and materials that utilize thermal energy are given.In addition to conventional macroscopic engines,based on thermoacoustic,thermomagnetic,thermoelastic,hydride heat converters,and shape memory alloys,the emergent devices are described which are classified as smart actuators,breathing frameworks,thermoacoustic micro-transducers,nanomechanical resonators,plasmomechanical systems,and optothermal walkers.The performance of the different types of thermomechanical energy converters is described and compared.

A comprehensive review of select smart polymeric and gel actuators for soft mechatronics and robotics applications:fundamentals,freeform fabrication,and motion control

Smart polymeric and gel actuators change shape or size in response to stimuli like electricity,heat,or light.These smart polymeric-and gel-based actuators are compliant and well suited for development of soft mechatronic and robotic devices.This paper provides a thorough review of select smart polymeric and gel actuator materials where an automated and freeform fabrication process,like 3D printing,is exploited to create custom shaped monolithic devices.In particular,the advantages and limitations,examples of applications,manufacturing and fabrication techniques,and methods for actuator control are discussed.Finally,a rigorous comparison and analysis of some of the advantages and limitations,as well as manufacturing processes,for these materials,are presented.

Design,Modeling,and Control of Biomimetic Fish Robot:A Review

A comprehensive review on bio-inspired fish robots has been done in this article with an enhanced focus on swimming styles,actuators,hydrodynamics,kinematic-dynamic modeling,and controllers.Swimming styles such as body and/or caudal fin and median and/or paired fin and their variants are discussed in detail.Literature shows that most fish robots adapt carangiform in body and/or caudal fin type swimming as it gives significant thrust with a maximum speed of 3.7 ms 1 in iSplash-II.Applications of smart or soft actuators to enhance real-time dynamics was studied from literature,and it was found that the robot built with polymer fiber composite material could reach a speed of 0.6 m s However,dynamic modeling is relatively complex,and material selection needs to be explored.The numerical and analytical methods in dynamic modeling have been investigated highlighting merits and demerits.Hydrodynamic parameter estimation through the data-driven model is widely used in offline,however online estimation of the same need to be explored.Classical controllers are frequently used tor navigation and stabilization,which often encounters the linearization problem and hence,can be replaced with the state-of-the-art adaptive and intelligent controller.This article also summarizes the potential research gaps and future scopes.