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Topic Review
Ni-Base Superalloys
Ni-base superalloys are materials largely used in aero-space and energy production sectors, in particular for manufacturing engine parts (e.g. blades, rotors, turbine disks etc.) of aircrafts and aerospace vehicles and parts of power plants (e.g. extraction of oil and gas, nuclear reactors, etc.). At high temperature they exhibit an exceptional combination of high mechanical strength and excellent corrosion resistance. Ni-base superalloys are considered materials of strategic importance and a lot of metallurgical research has been devoted for optimizing their microstructure and improving mechanical properties so that they can operate at ever higher temperature in conditions of safety and reliability. Ni-base superalloys are strengthened by the precipitation of the ordered γ' phase, L12 Ni3(Al,Ti), crystallographically coherent to the f.c.c. γ matrix and their unique mechanical properties at high temperature result from the great microstructure stability. The volume fraction of γ' phase varies from 25% to 50% in polycrystalline superalloys and reaches about 70% in the most modern single crystal superalloys used for the first stage of aeronautical turbine blades. In order to reduce as much as possible the strain misfit between coherent γ and γ' phases (less than 0.4%) they are designed by an accurate tailoring of the chemical composition and a strict control of the process parameters; the resulting interface energy (20-30 mJ/m2) guarantees an excellent stability of the microstructure at high temperature. Other phases such as carbides, borides, γ'', η, δ, σ, µ and Laves phases may be also present with various effects on the mechanical properties; for instance, the topological closed-packed (TCP) σ, µ and Laves phases are undesirable because reduce the ductility.  In spite of the fact that Ni-base superalloys cost from 3 to 5 times the Fe-base ones, their use is expanding especially in gas turbine components for the production of energy because higher temperature of the thermal cycle guarantees greater efficiency and reduction of polluting emission. The demand of Ni-base superalloys is expected to expand also for the energy production through conventional steam turbine plants for achieving super-critical conditions with a predicted increase of efficiency to ~ 60% and reduction of CO2 to about 0.7 ton/kWatth while current sub-critical power plants have an efficiency of ~ 35% and produce 1.2 ton/kWatth of CO2. Of course, higher operating temperature involves more severe degradation of mechanical properties owing to these factors: (i) microstructure evolution including formation of undesired phases, coalescence of γ' precipitates, degeneration of carbides due to fatigue and creep exposure etc.; ii) the formation of cracks. Three topics of great industrial relevance will be discussed hereinafter: (i) microstructural stability; (ii) manufacturing parts of complex geometry; (iii) welding of superalloys. 
  • 916
  • 16 Feb 2022
Topic Review
Indoor Positioning System
The indoor positioning system (IPS) provides continuous real-time localization of objects or people within an enclosed space in different environments, using a network of transmitters and receivers. Indoor localization is more complex than outdoor localization because the indoor communication channel varies significantly with the environment and depends heavily on many factors, such as building structure, room layout, and construction materials.
  • 916
  • 16 Dec 2022
Topic Review
WEC with Linear Generator-Based Direct Electric-Drive PTO System
The traditional wave energy converters (WECs) use hydraulic or turbine-type power take-off (PTO) mechanisms which consist of many moving parts, creating mechanical complexity and increasing the installation and maintenance costs. Linear generator-based direct-drive WECs could be a solution to overcome this problem. 
  • 916
  • 01 Sep 2022
Topic Review
Computer Vision Applications in Intelligent Transportation Systems
As technology continues to develop, computer vision (CV) applications are becoming increasingly widespread in the intelligent transportation systems (ITS) context. These applications are developed to improve the efficiency of transportation systems, increase their level of intelligence, and enhance traffic safety. Advances in CV play an important role in solving problems in the fields of traffic monitoring and control, incident detection and management, road usage pricing, and road condition monitoring, among many others, by providing more effective methods.
  • 916
  • 21 Mar 2023
Topic Review
GeForce 6 Series
The GeForce 6 series (codename NV40) is Nvidia's sixth generation of GeForce graphic processing units. Launched on April 14, 2004, the GeForce 6 family introduced PureVideo post-processing for video, SLI technology, and Shader Model 3.0 support (compliant with Microsoft DirectX 9.0c specification and OpenGL 2.0).
  • 915
  • 21 Nov 2022
Topic Review
Dehydrogenation and Oxidative Dehydrogenation of Propane to Propylene
Propylene is one of the most important building blocks in the petrochemical industry. It is industrially employed to produce polypropylene, which is used extensively to make packaging and labeling, textile products, laboratory equipment, loudspeakers, and automotive components. Propylene is also used for the manufacturing of acrylonitrile, propylene oxide derivatives, and other substances. Catalytic propane oxidative dehydrogenation (PODH) in the absence of gas phase oxygen is a promising approach for propylene manufacturing. PODH can overcome the issues of over-oxidation, which lower propylene selectivity. PODH has a reduced environmental footprint when compared with conventional oxidative dehydrogenation, which uses molecular oxygen and/or carbon dioxide.
  • 915
  • 21 Jun 2022
Topic Review
Major Synthetic Fuels
A concise yet comprehensive overview of major synthetic fuels currently in production worldwide. The fuels are virtually categorised in an intelligible manner with detailed descriptions of their chemical equations, feedstocks, production processes, applications, and global market leaders.
  • 915
  • 27 Mar 2023
Topic Review
Animated Cartoon
An animated cartoon is a film for the cinema, television or computer screen, which is made using sequential drawings, as opposed to animation in general, which include films made using clay, puppets, 3D modeling and other means. Animated cartoons are still created for entertainment, commercial, educational and personal purposes.
  • 915
  • 18 Nov 2022
Topic Review
Spinal Robotic Orthoses
Osteoporotic spine fractures (OSF) are common sequelae of osteoporosis. OSF are directly correlated with increasing age and incidence of osteoporosis. OSF are treated conservatively or surgically. We review the current state of the art in the field of wearable robots for trunk support.
  • 914
  • 19 Feb 2021
Topic Review
Application of CFD to Food 3D Printing
CFD (Computational Fluid Dynamics) is one of the computer simulation methods used to characterize fluid flow behavior under certain geometries with boundary conditions. The criterion for its performance is how well numerical simulation outcomes align with experimental results conducted under specific conditions, and how well simulations can predict extremely complicated processes that cannot be analyzed in the real world. CFD has gained recognition as an emerging science around the world, particularly since the late 2000s when there was a significant increase in the development and application of CFD to all areas related to fluid behaviors associated with momentum, heat, and mass transfer.
  • 914
  • 12 Nov 2021
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