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Topic Review
High-Temperature Materials in Ammonia/Hydrogen Gas Turbines
This entry reviews the critical role of material selection and design in ensuring efficient performance and safe operation of gas turbine engines fuelled by ammonia–hydrogen. As these energy fuels present unique combustion characteristics in turbine combustors, the identification of suitable materials becomes imperative. Detailed material characterisation is indispensable for discerning defects and degradation routes in turbine components, thereby illuminating avenues for improvement. With elevated turbine inlet temperatures, there is an augmented susceptibility to thermal degradation and mechanical shortcomings, especially in the high-pressure turbine blade—a critical life-determining component.
  • 1.4K
  • 17 Oct 2023
Topic Review
Minimum Energy Performance Standards in Colombia
The minimum energy performance standards (MEPS) has become a mandatory government document to evaluate the energy efficiency of different equipment and thus limit the minimum energy consumption in domestic, commercial, and industrial applications, guaranteeing end users are able to select more efficient equipment. In order to be compared with the Colombian panorama at the market, technical and political levels, some reference countries and their energy policies were consulted. This allows the establishment of common aspects and differences related to the determination of energy consumption, adjusted volume, and formalization of efficiency ranges, and in the specific case of domestic refrigeration in Colombia.
  • 1.4K
  • 10 Feb 2023
Topic Review
Arch-Dams’ Building Risk Reduction
The are thousands of large dams over the globe. The importance of dams is rapidly increasing due to the impact of climate change on increasing hydrological process variability and on water planning and management need. This study tackles a review for the concrete arch-dams’ design process, from a dual sustainability/safety management approach. On one hand, Sustainability is evaluated through a design optimization for dams´ stability and deformation analysis. On the other hand, safety is directly related to the reduction and consequences of failure risk. For that, several scenarios about stability and deformation, identifying desirable and undesirable actions, were estimated. More than 100 specific parameters regarding dam-reservoir-foundation-sediments system and their interactions have been collected. Also, a summary of mathematical modelling was made, and more than 100 references were summarized. The following consecutive steps, required to design engineering (why act), maintenance (when to act) and operations activities (how to act), were evaluated: individuation of hazards, definition of failure potential and estimation of consequences (harm to people, assets and environment). Results show that the area to model the dam–foundation interaction is around 3.0 Hd2, the system-damping ratio and vibration period is 8.5% and 0.39 s. Also, maximum elastic and elasto-plastic displacements are ~0.10–0.20 m. The failure probability for stability is 34%, whereas for deformation it is 29%
  • 1.4K
  • 30 Oct 2020
Topic Review Peer Reviewed
Elevator Technology Improvements: A Snapshot
Efficient vertical transportation is vital to a skyscraper’s functional operation and the convenience and satisfaction of its tenants. This review complements the author’s previously published research by updating the readers on innovative hardware and software-based solutions. It lays out, organizes, and combines extensive and scattered material on numerous aspects of elevator design in a straightforward and non-technical narrative. Rope-less elevators, the MULTI, artificial intelligence (AI), the Internet of Things (IoT), and extended reality technologies are some of the developments and advancements this article examines. The analysis also contextualizes current technical developments by reviewing how they are used in significant projects such as the One World Trade Center in New York City. Lastly, the paper examines innovative technologies, such as holographic elevator buttons and ultraviolet rays that disinfect elevators, in response to the COVID-19 pandemic.
  • 1.4K
  • 04 May 2023
Topic Review
Thermal Management System
In gas turbine engines, Thermal Management (TM) is a concept of utilising the engine fluid systems to extract the excess heat generated within the various components and systems of the engine as well as employing the extracted heat for multiple functions that would improve the engine’s performance.
  • 1.4K
  • 14 Jan 2022
Topic Review
Development of Electrostatic Microactuators
Operation with micrometric size objects requires a change in the entire paradigm in manipulation equipment and particularly in the field of related actuators. Microactuators have low energy efficiency compared to the devices of macroscale. The dimensions of these drives are so small that standard kinematic arrangement is not applicable. On the other hand, the small size allows the use of lower mechanical parameters materials due to the dimensional limits of the micromechanisms. With the development of the biological industry, these actuators became a key for living cell positioning, high-speed microscopy, and other micro-scale technologies. New emerging transducer materials such as magnetic nanoparticles, metallic nanoparticles, expandable micro-spheres, and conductive polymers can be used for the design of micro-scale sensors and actuators. Despite the used materials, the surface effects and inter-molecular interactions are important in micro-scale; in nanoscale, these phenomena become essential. Micro/nanoelectromechanical systems (MEMSs/NEMSs) with electrostatic drives have fast response, are power efficient, and fit well for micro- and nanopositioning. Drive operating voltage, response speed, operating stroke, generated force, and the accumulated amount of energy define these actuators’ application area. The electrostatic actuators suffer from the pull-in phenomenon (loss of the equilibrium between attractive and repulsive forces), limiting their performance. This limitation could be overcome by developing actuators based on repulsive force or electrostatic levitation.
  • 1.4K
  • 26 Aug 2022
Topic Review
Nickel-Titanium Rotary Instruments in Endodontics
Since the introduction of Nickel-Titanium alloy as the material of choice for the manufacturing of endodontic rotary instruments, the success rate of the root canal therapies has been significantly increased. This success mainly arises from the properties of the Nickel-Titanium alloy: the biocompatibility, the superelasticity and the shape memory effect. Those characteristics have led to a reduction in time of endodontic treatments, a simplification of instrumentation procedures and an increase of predictability and effectiveness of endodontic treatments. Nevertheless, the intracanal separation of Nickel-Titanium rotary instruments is still a major concern of endodontists, with a consequent possible reduction in the outcome rate. As thoroughly demonstrated, the two main causes of intracanal separation of endodontic instruments are the cyclic fatigue and the torsional loads. As results, in order to reduce the percentage of intracanal separation researches and manufacturers have been focused on the parameters that directly or indirectly influence mechanical properties of endodontic rotary instruments. This entry describes the current state of the art regarding the Nickel-Titanium alloy in endodontics, the mechanical behavior of endodontic rotary instruments and the relative stresses acting on them during intracanal instrumentation, highlighting the limitation of the current literature.
  • 1.4K
  • 24 Jan 2022
Topic Review
The Pipeline Finite Element Analysis Model
Pipelines are widely used to transport oil and gas products over long distances. Corrosion and crack defects often exist at the same time in pipelines. The interaction impact between these defects could potentially affect the growth of the fatigue crack. Ensuring pipeline safety is a prerequisite for the transportation of fuels such as oil and natural gas. The finite element models are built to obtain the Stress Intensity Factors (SIFs) for fatigue crack. SIF interaction impact ratio is introduced to describe the interaction effect of corrosion on fatigue crack.
  • 1.4K
  • 17 Feb 2022
Topic Review
Additive Manufacturing of Magnesium-Based Alloys through Laser-Based Approach
Magnesium alloys continue to be important in the context of modern and lightweight technologies. The increased use of Mg each year indicates a rise in demand for alloys containing Mg. With additive manufacturing (AM), components can be produced directly in a net shape, providing new ideas relating to the new prospects for Mg-based materials. 
  • 1.3K
  • 23 Nov 2022
Topic Review
Metal Hydrides
A metal hydride is a compound formed between a metal and hydrogen, in which the hydrogen atoms are bonded to the metal atoms through chemical bonds. Metal hydrides have a wide range of applications as energy storage materials, catalysts, and structural materials.
  • 1.3K
  • 21 Apr 2023
Topic Review
Ultrasonic Vibration-Assisted Ball-Burnishing Process
Burnishing processes are effective methods to increase the durability and surface texture of industrial parts, through plastic deformation of its micropeaks. Traditional burnishing can be strongly improved with the assistance of external energy sources. One of these sources is vibration assistance, which can be delivered into the systems through different means. In overall, vibration-assistance ball burnishing consists on overlapping to the static burnishing preload an oscillatory force that favours the acoustoplastic effect in the material, that is, an increase in dislocation mobility that facilitates plastic deformation, while eventually delivering residual hardening on the target surface.
  • 1.3K
  • 11 Jun 2021
Topic Review
Experimental Studies of PCM Building Applications
The use of phase change material (PCM) as a thermal energy storage system integrated in new buildings, and as retrofits in old buildings, proved its merit as promising renewable energy source. Experimental investigations for the use of PCM in buildings gained attention where the experimental setups used are classified as: Large-scale, small-scale, retrofitting, and laboratory-based test facilities.
  • 1.3K
  • 22 Mar 2022
Topic Review
Unmanned Aerial Vehicles for Search and Rescue
The use of unmanned aerial vehicles (UAVs) in search and rescue (SAR) can greatly enhance the task success rates in reaching inaccessible or dangerous areas, performing challenging operations, and providing real-time monitoring and modeling of the situation.
  • 1.3K
  • 03 Aug 2023
Topic Review
Liquid-Based 3DP Techniques
Significant advances have been made in recent years in the materials development of liquid-based 4D printing. Nevertheless, employing additive materials such as nanoparticles for enhancing printability and shape memory characteristics is still challenging. Herein, researchers provide an overview of recent developments in liquid-based 4D printing and highlight novel 4D-printable polymeric resins and their nanocomposite components. Recent advances in additive manufacturing technologies that utilise liquid resins, such as stereolithography, digital light processing, material jetting and direct ink writing, are considered. The effects of nanoparticle inclusion within liquid-based resins on the shape memory and mechanical characteristics of 3D-printed nanocomposite components are comprehensively discussed. Employing various filler-modified mixture resins, such as nanosilica, nanoclay and nanographene, as well as fibrous materials to support various properties of 3D printing components is considered.
  • 1.3K
  • 23 Feb 2023
Topic Review
System-Level Prognostics
Condition-based maintenance (CBM) is a maintenance policy that maintains the reliability of system operation and reduces the downtime of the system. Prognostics and health management (PHM) has attracted much attention as the enabler of CBM. The PHM aims to predict the remaining useful life (RUL) of the system and suggest an optimal health management strategy.
  • 1.3K
  • 03 Dec 2021
Topic Review
COVID-19 Spread Faster with HVAC
Droplets and aerosolized viral particles expelling from the body through coughing or sneezing and it is spreading to nearby surroundings. CFD model has been developed to simulate the air flow and the transport and dispersion of the aerosolized viral particles and fine droplets suspended in the air particles through the office. The study presents two cases involving the spreading limits and pathways of the aerosolized viral particles and fine droplets suspended in the air in a place; without and with air conditioning unit. The results showed that the use of air conditioning systems can increase the chances of spreading COVID-19 virus infection. The air-conditioning unit recirculates the same air inside a room, and this has the potential to create a virus-laden environment. Air circulation indoors such as using air conditioning units should be avoided in closed places. Existing ventilation systems should be expanded to include extraction and air filtration systems and/or germicidal, ultraviolet light. Also, opening a window can help bring in fresh air from the outside and disperse stale air inside, and that could help reduce the possibility of the spread of the virus particles in the closed place. Lastly, crowds of people in closed public places should be avoided (HVAC: Heating, ventilation, and air conditioning).
  • 1.3K
  • 17 Feb 2021
Topic Review
Vehicle Design and Technology for Reducing Fuel Consumption
In recent times, the significance of advancing road transportation technologies has notably increased. This is mainly driven by the escalating need for road transportation systems that are not only safe but also environmentally sustainable. Moreover, enhancing fuel efficiency in road vehicles (i.e., automobiles) holds the potential to contribute significantly to the reduction of a country’s economic vulnerability (i.e., improved energy security), by reducing the reliance on energy imports. 
  • 1.2K
  • 29 Jan 2024
Topic Review
Classification of Lattice Structure
A lattice structure is made by a unit cell that is repeated in the space, making a larger functional structure; thus, it is a peculiar kind of cellular structure. The basic idea of cellular structures evolved from natural organic structures such as bamboo, bone, cork, etc. According to the literature, in many applications, lattice structures have been found to be superior to their other cellular counterparts, such as foam and honeycomb structures.
  • 1.2K
  • 12 Oct 2023
Topic Review
Joint Configuration and Geometry
The use of carbon fibre-reinforced polymer (CFRP) materials is increasing in many different industries, such as those operating in the aviation, marine, and automotive sectors. In these applications, composite parts are often joined with other composite or metallic parts, where adhesive bonding plays a key role. 
  • 1.2K
  • 17 Jan 2023
Topic Review
Global Plastic Waste is Increasing
Global plastic waste is increasing rapidly. In general, densely populated regions generate tons of plastic waste daily, which is sometimes disposed of on land or diverged to sea. Most of the plastics created in the form of waste have complex degradation behavior and are non-biodegradable by nature. These remain intact in the environment for a long time span and potentially originate complications within terrestrial and marine life ecosystems. The strategic management of plastic waste and recycling can preserve environmental species and associated costs. 
  • 1.2K
  • 24 Sep 2021
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