Abstract The global energy crisis and environmental pollutions caused mainly by the increased consumption of nonrenewable energy sources prompted researchers to explore alternative energy technologies that can harvest energies available in the ambient environment. Mechanical energy is the most ubiquitous ambient energy that can be captured and converted into useful electric power. Piezoelectric transduction is the prominent mechanical energy harvesting mechanism owing to its high electromechanical coupling factor and piezoelectric coefficient compared to electrostatic, electromagnetic, and triboelectric transductions. Thus, piezoelectric energy harvesting has received the utmost interest by the scientific community. Advancements of micro and nanoscale materials and manufacturing processes have enabled the fabrication of piezoelectric generators with favorable features such as enhanced electromechanical coupling factor, piezoelectric coefficient, flexibility, stretch-ability, and integrate-ability for diverse applications. Besides that, miniature devices with lesser power demand are realized in the market with technological developments in the electronics industry. Thus, it is anticipated that in near future, many electronics will be powered by piezoelectric generators. This paper presents a comprehensive review on the state-of-the-art of piezoelectric energy harvesting. The piezoelectric energy conversion principles are delineated, and the working mechanisms and operational modes of piezoelectric generators are elucidated. Recent researches on the developments of inorganic, organic, composite, and bio-inspired natural piezoelectric materials are reviewed. The applications of piezoelectric energy harvesting at nano, micro, and mesoscale in diverse fields including transportation, structures, aerial applications, in water applications, smart systems, microfluidics, biomedicals, wearable and implantable electronics, and tissue regeneration are reviewed. The advancements, limitations, and potential improvements of the materials and applications of the piezoelectric energy harvesting technology are discussed. Briefly, this review presents the broad spectrum of piezoelectric materials for clean power supply to wireless electronics in diverse fields.
Processing of materials by ultrashort laser pulses has evolved significantly over the last decade and is starting to reveal its scientific, technological and industrial potential. In ultrafast laser manufacturing, optical energy of tightly focused femtosecond or picosecond laser pulses can be delivered to precisely defined positions in the bulk of materials via two-/multi-photon excitation on a timescale much faster than thermal energy exchange between photoexcited electrons and lattice ions. Control of photo-ionization and thermal processes with the highest precision, inducing local photomodification in sub-100-nm-sized regions has been achieved. State-of-the-art ultrashort laser processing techniques exploit high 0.1–1 μm spatial resolution and almost unrestricted three-dimensional structuring capability. Adjustable pulse duration, spatiotemporal chirp, phase front tilt and polarization allow control of photomodification via uniquely wide parameter space. Mature opto-electrical/mechanical technologies have enabled laser processing speeds approaching meters-per-second, leading to a fast lab-to-fab transfer. The key aspects and latest achievements are reviewed with an emphasis on the fundamental relation between spatial resolution and total fabrication throughput. Emerging biomedical applications implementing micrometer feature precision over centimeter-scale scaffolds and photonic wire bonding in telecommunications are highlighted. The ability of femtosecond lasers to efficiently fabricate complex structures and devices for a wide variety of applications is reviewed. Mangirdas Malinauskas at Vilnius University in Lithuania and co-workers in Japan, Australia and Saudi Arabia describe how state-of-the-art laser processing techniques with ultrashort light pulses can be used to structure materials with a sub-micrometre resolution. Direct laser writing of suitable photoresists and other transparent media can create intricate three-dimensional photonic crystals, micro-optical components, gratings, tissue scaffolds and optical waveguides. Such structures are potentially useful for empowering next-generation applications in telecommunications and bioengineering that rely on the creation of increasingly sophisticated miniature parts. The precision, fabrication speed and versatility of ultrafast laser processing make it well placed to become a vital industrial tool for manufacturing.
Natural fibers are getting attention from researchers and academician to utilize in polymer composites due to their ecofriendly nature and sustainability. The aim of this review article is to provide a comprehensive review of the foremost appropriate as well as widely used natural fiber reinforced polymer composites (NFPCs) and their applications. In addition, it presents summary of various surface treatments applied to natural fibers and their effect on NFPCs properties. The properties of NFPCs vary with fiber type and fiber source as well as fiber structure. The effects of various chemical treatments on the mechanical and thermal properties of natural fibers reinforcements thermosetting and thermoplastics composites were studied. A number of drawbacks of NFPCs like higher water absorption, inferior fire resistance, and lower mechanical properties limited its applications. Impacts of chemical treatment on the water absorption, tribology, viscoelastic behavior, relaxation behavior, energy absorption flames retardancy, and biodegradability properties of NFPCs were also highlighted. The applications of NFPCs in automobile and construction industry and other applications are demonstrated. It concluded that chemical treatment of the natural fiber improved adhesion between the fiber surface and the polymer matrix which ultimately enhanced physicomechanical and thermochemical properties of the NFPCs.
Abstract Additive manufacturing (AM) has the potential to disrupt the ceramic industry by offering new opportunities to manufacture advanced ceramic components without the need for expensive tooling, thereby reducing production costs and lead times and increasing design freedom. Whilst the development and implementation of AM technologies in the ceramic industry has been slower than in the polymer and metal industries, there is now considerable interest in developing AM processes capable of producing defect-free, fully dense ceramic components. A large variety of AM technologies can be used to shape ceramics, but variable results have been obtained so far. Selecting the correct AM process for a given application not only depends on the requirements in terms of density, surface finish, size and geometrical complexity of the part, but also on the nature of the particular ceramic to be processed. This paper provides a detailed review of the current state-of-the-art in AM of advanced ceramics through a systematic evaluation of the capabilities of each AM technology, with an emphasis on reported results in terms of final density, surface finish and mechanical properties. An in-depth analysis of the opportunities, issues, advantages and limitations arising when processing advanced ceramics with each AM technology is also provided.
Abstract Portland cement manufacture emits 5–7% CO2, which is responsible for global warming. Geopolymers minimize CO2 emission and may be a partial alternative to Portland cement in the building industry. The geopolymer technology gives solution to the utilization of industrial byproducts (waste) containing aluminosilicate phases with little negative impact on environment. Geopolymer cements are mainly produced by using secondary raw materials such as fly ash, metakaolin, calcined clays, zeolite etc. by the activation of alkali/alkali silicate solutions. Combination of different source materials containing aluminosilicate and alkali solutions with optimization of curing temperature, alkali concentrations, additives, Na2O/SiO2 ratio etc. gives geopolymer cements of high mechanical and durability properties. Due to their high mechanical properties and environmental benefit, geopolymer cement and concrete appear as a future prospective construction material and have applications in different areas.
Sensors are becoming increasingly significant in our daily life because of the rapid development in electronic and information technologies, including Internet of Things, wearable electronics, home automation, intelligent industry, etc. There is no doubt that their performances are primarily determined by the sensing materials. Among all potential candidates, layered nanomaterials with two-dimensional (2D) planar structure have numerous superior properties to their bulk counterparts which are suitable for building various high-performance sensors. As an emerging 2D material, MXenes possess several advantageous features of adjustable surface properties, tunable bandgap, and excellent mechanical strength, making them attractive in various applications. Herein, we particularly focus on the recent research progress in MXene-based sensors, discuss the merits of MXenes and their derivatives as sensing materials for collecting various signals, and try to elucidate the design principles and working mechanisms of the corresponding MXene-based sensors, including strain/stress sensors, gas sensors, electrochemical sensors, optical sensors, and humidity sensors. In the end, we analyze the main challenges and future outlook of MXene-based materials in sensor applications.
High‐performance elastomers have gained significant interest because of their wide applications in industry and our daily life. However, it remains a great challenge to fabricate elastomers simultaneously integrating ultra‐high mechanical strength, toughness, and excellent healing and recycling capacities. In this study, ultra‐strong, healable, and recyclable elastomers are fabricated by dynamically cross‐linking copolymers composed of rigid polyimide (PI) segments and soft poly(urea–urethane) (PUU) segments with hydrogen bonds. The elastomers, which are denoted as PIPUU, have a record‐high tensile strength of ≈142 MPa and an extremely high toughness of ≈527 MJ m−3. The structure of the PIPUU elastomer contains hydrogen‐bond‐cross‐linked elastic matrix and homogenously dispersed rigid nanostructures. The rigid PI segments self‐assemble to generate phase‐separated nanostructures that serve as nanofillers to significantly strengthen the elastomers. Meanwhile, the elastic matrix is composed of soft PUU segments cross‐linked with reversible hydrogen bonds, which largely enhance the strength and toughness of the elastomer. The dynamically cross‐linked PIPUU elastomers can be healed and recycled to restore their original mechanical strength. Moreover, because of the excellent mechanical performance and the hydrophobic PI segments, the PIPUU elastomers are scratch‐, puncture‐, and water‐resistant.
Shah‐Al Emran, Bryan M. Petersen, Heather Elizabeth Roney
et al.
ABSTRACT The cultivation of sterile giant miscanthus (Miscanthus × giganteus, M × g) for bioenergy and bioproducts has expanded into grain‐cropped land in the United States (US) as local markets developed for this high‐yielding perennial grass (10–30 Mg DM ha−1). However, the magnitude of spatial and temporal variability in yield within US Corn Belt fields, along with impacts on economic return and sustainable land management, is poorly understood. This study established a diagnostic model relating remote sensing‐derived vegetation indices to ground truth data from 105 hand‐harvested stem biomass samples, which were strategically selected to represent the full range of vegetation index observations. The high‐resolution satellite‐sensed vegetation indices captured > 90% of the yield variation measured within fields. This model was then used to predict yield variability and assess economic performance across four of the first commercial M × g fields in the Corn Belt state of Iowa, US. Significant spatial variability in biomass dry matter (DM) yields (9.3–18.1 Mg DM ha−1) and net profits ($83 to $1211.5 ha−1) was observed. All fields were profitable in all site‐years. When low profit occurred, it was explained by limited management experience of the crop in Iowa. The breakeven yield at a selling price of $130 Mg−1 varied from 9.0–12.1 Mg ha−1 at 15% moisture content (7.6–10.3 Mg DM ha−1). Breakeven prices ranged from $73 to $122.4 Mg−1, matching ranges used in the Department of Energy Billion Ton Report (US Department of Energy, 2023). Notably, M × g yield and profits were commensurate with grain crops particularly with favorable precipitation. This study provides insight on the M × g management “learning curve”, performance on marginal land and in drought conditions, and demonstrates that addressing yield gaps, reducing costs, and implementing precision agriculture strategies can enhance profitability. These findings emphasize the value of remote sensing technologies in guiding sustainable and competitive commercial‐scale M × g production.
Renewable energy sources, Energy industries. Energy policy. Fuel trade
Sudarshan L. Chavan, Manjusha A. Kanawade, Rahul S. Ankushe
ABSTRACT: The increasing demand for clean transportation has propelled research and development in electric vehicles (EVs), with a crucial focus on enhancing battery technologies. This paper presents a novel approach to a battery management system by implementing a passive cell balancing system for lithium-ion battery packs. The proposed system employs a proportional-integral (PI) controller to address voltage imbalances among individual cells, aiming to improve battery life and longevity without the need for a complex active control circuit. The study explores performance evaluation under diverse conditions, considering factors such as system capacity retention, energy efficiency, and overall reliability. Safety and thermal management considerations play a crucial role in the implementation, ensuring the longevity and stability of the lithium-ion battery pack. The primary objective of this research is to extend the operational life of lithium-ion batteries, reduce maintenance costs associated with battery management, and contribute to sustainable energy solutions. In the presented study, first, a Simulation model is developed in MATLAB, and the results are verified by implementing a hardware model.
Energy industries. Energy policy. Fuel trade, Renewable energy sources
Abstract Natural gas hydrates (NGHs) offer significant potential for energy recovery and carbon sequestration, yet the thermal stability of polycrystalline CH4-CO2 hydrates (PCCHs) which is critical for CO2-based NGH exploitation, remains poorly understood. Here, we unravel CO2’s role in reshaping the thermal dissociation behaviors of PCCHs via high-throughput molecular dynamics (MD) simulations and machine learning (ML). We demonstrate that CO2 reduces the stability of PCCHs, with a 20% increase in CO2 concentration lowering the melting point by approximately 6 K. Microstructural analysis reveals that this destabilization arises from CO2-induced distortion of 512 cage and formation of unconventional metastable cages. Thermal dissociation occurs via cage transformations and dissociations, where 4151062 and 51262 cages act as hubs for solid–solid restructuring pathway. Crucially, CH4 guest molecules facilitate simpler, faster cage transformations than CO2, which requires complex rearrangements. We further develop a GBDT ML model that accurately predicts PCCH melting points using microstructural information, identifying 512, 51262, and 51063 cages as key predictors. This model provides a practical tool for guiding CO2-based NGH exploitation and designing hydrate storage systems. These insights advance the molecular-level understanding of hydrate stability for CO2 sequestration and NGH recovery. Graphical Abstract
Energy industries. Energy policy. Fuel trade, Renewable energy sources
This study presents the first comprehensive investigation into the Additive Manufacture (AM) of nickel-based Alloys 690 and 52i using Laser Powder Bed Fusion (LPBF), with a view towards application in high-temperature, corrosion-resistant components for nuclear and power generation industries. Specimens fabricated from gas atomised powder achieved almost full density (99.95 %) and underwent a conventional solution anneal heat treatment. A comprehensive set of microstructural, mechanical property, and corrosion properties was undertaken to assess their performance viability.LPBF Alloy 52i demonstrated superior 0.2 % Proof Strength (PS) and Ultimate Tensile Strength (UTS) compared to both wrought and LPBF Alloy 690, at ambient and elevated temperatures (300 °C), for all build orientations. Strength differences between orientations were attributed to microstructural anisotropy, consistent with wrought studies. Microstructural characterisation revealed differences in pore morphology, carbide distribution and oxide inclusions; with LPBF Alloy 52i exhibiting plate-like aluminium oxides linked to higher oxygen content of the virgin powder.Corrosion testing indicated enhanced intergranular corrosion resistance in both LPBF alloys compared to wrought Alloy 690, attributed to finer and more continuous grain boundary carbides. These results support the potential of LPBF Alloys 690 and 52i for structural applications in demanding environments and provide early data for material qualification efforts in nuclear engineering.
In this study, the torsional mode shapes of circular and non-circular functionally graded material shafts, focusing on triangular, rectangular, circular cross-sections are investigated. The shafts are composed of an aluminum-titanium (AlTi) alloy and various functionally graded materials, utilizing different mixing rules to create a gradient surface. The modal analysis is conducted using ANSYS Mechanical leading finite element analysis software to assess and visualize the vibrational characteristics of these shafts under torsional loading. Then, the same shafts made of isotropic material (pure Al) is prepared, and compared with respect to results. The objective is to understand the influence of FGMs compared to homogeneous and isotropic materials on the torsional behavior of shafts with non-circular geometries. By comparing the torsional mode shapes and frequencies, one can identify the distinct vibrational properties introduced by the gradient material composition. This comparison is highlight the potential advantages of FGM shafts in applications requiring tailored mechanical properties that traditional homogeneous materials cannot provide. The study also explores how the different cross-sectional shapes affect the torsional response, which is crucial for designing components subjected to twisting loads in aerospace, automotive, and construction industries. The results from ANSYS Mechanical are analyzed to extract the mode shapes and frequencies of torsional modes, providing a comprehensive understanding of how FG materials behave relative to isotropic counterparts under similar conditions. The study aims to show how the natural frequency and torsional mode shapes differ for a functionally graded material compared to isotropic material, may be useful for researchers working with applications where vibration behavior is crucial.