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Topic Review Peer Reviewed
Exsolution Catalysts—Increasing Metal Efficiency
Exsolution catalysts are perovskite oxide-based materials that can exsolve catalytically active dopant elements as nanoparticles covering the surface, while the perovskite backbone can act as a stable support material. Thus, under proper conditions, a highly catalytically active and stable catalyst surface can be achieved. For many catalytic materials, precious metals or non-abundant elements play a key role in high catalytic activity. As these elements are often expensive or their supply is ecologically and ethically problematic, the replacement, or at the least reduction in the necessary amount used, is a common aim of current research. One strategy to do so is utilizing exsolution catalysts, as the active elements can be very selectively exsolved, and hence only very small doping amounts are sufficient for excellent results. This approach enables catalyst design with very high active metal efficiency.
  • 964
  • 13 Apr 2022
Topic Review
External Human–Machine Interface of AVs
In future urban traffic, it is more likely that automated vehicles (AVs) will operate not in separated traffic spaces but in so-called mixed traffic environments where different types of traffic participants interact. Therefore, AVs must be able to communicate with other traffic participants, e.g., pedestrians as vulnerable road users (VRUs), to solve ambiguous traffic situations. Taking current traffic communication patterns into account, a combination of implicit communication via the driving behavior (e.g., deceleration, position in lane) and explicit communication via an external Human–Machine Interface (eHMI) seems to be a promising approach. The eHMI consists of an external interface connected to the vehicle, which can transmit explicit signals enabling interaction between AVs and other TPs.
  • 829
  • 15 Aug 2021
Topic Review
Fe-Based Magnetic Amorphous Alloys
Amorphous alloys for soft magnetic applications are often fabricated by rapid solidification of the melt. They are generally prepared with the nearly 20% addition of metalloids (Si, B, Al, C and P) for Fe-based and Co-based alloys. Si and B are important metalloids for glass formation and the amorphous structure stabilisation. Typical chemical compositions are such that the combined compositions of Fe, Co, Ni elements are 70–85 atomic (at.)% and those of Si and B are 15–30 at.% in total. However, magnetic glassy alloys have a wide variety of compositions. This allows for a large range of soft magnetic properties to be achieved, which depend upon the demands of the application.
  • 1.2K
  • 28 Apr 2021
Topic Review
Flight Operations on the Risk of Runway Excursions
The Quick Access Recorder (QAR), as an onboard device used for monitoring and recording flight parameters, has been extensively installed on various types of aircraft. Ensuring safety during the landing phase has always been a top priority for the civil aviation industry.
  • 97
  • 07 Feb 2024
Topic Review
Generative Algorithms in Human-Centered Product Development
Algorithmic design harnesses the power of computation to generate a form based on input data and rules. In the product design setting, a major advantage afforded by this approach is the ability to automate the customization of design variations in accordance with the requirements of individual users. The background knowledge, intuition, and critical judgement of the designer are still essential but are focused on different areas of the design process.
  • 401
  • 06 May 2022
Topic Review
Heat and Moisture Transfer in Clothing Materials
Clothing as a tool connecting the human body and environment provides thermal and moisture comfort, and protective performance in cold, moderate, and extremely hot environments. The heat and moisture transfer properties of clothing materials are commonly evaluated using experimental study, mathematical modeling, and computer simulation.
  • 510
  • 08 Feb 2023
Topic Review
High-Temperature Shape Memory Alloys
With the aim to improve the strength of high-temperature shape memory alloys, multi-component alloys, including medium- and high-entropy alloys, have been investigated and proposed as new structural materials. Notably, it was discovered that the martensitic transformation temperature could be controlled through a combination of the constituent elements and alloys with high austenite finish temperatures above 500 °C. The irrecoverable strain decreased in the multi-component alloys compared with the ternary alloys. The repeated thermal cyclic test was effective toward obtaining perfect strain recoveries in multi-component alloys, which could be good candidates for high-temperature shape memory alloys.
  • 2.6K
  • 26 Nov 2020
Topic Review
Indoor Electronic Travel Aid for Visually Impaired Individuals
Most navigation aids for visually impaired individuals require users to pay close attention and actively understand the instructions or feedback of guidance, which impose considerable cognitive loads in long-term usage. The “Aerial Guide Dog”, a helium balloon aerostat drone designed for indoor guidance, which leverages gentle tugs in real time for directional guidance, ensuring a seamless and intuitive guiding experience. The introduced Aerial Guide Dog has been evaluated in terms of directional guidance and path following in the pilot study, focusing on assessing its accuracy in orientation and the overall performance in navigation.
  • 92
  • 18 Jan 2024
Topic Review
Intermediate Strain Rate Testing Devices
The existing experimental tests are mainly designed to study the mechanical response of materials at various strain rates. Many researchers performed the experimental test in tension, compression, and shear (with torsion test) over a wide range of strain rates. They found out that material exhibits an increase in yield stress as well as flows stress with an increase in strain rate. It illustrates that there is a need for experimental data to study the material behaviour over the full range of strain rates, from quasi-static to high strain rate test. Many special techniques have been developed to bridge the strain rate gap between quasi-static and high strain rate testing to provide a method for an intermediate strain rate test for engineering materials. Some researchers have tried to conduct intermediate strain rate tests with standard servo-hydraulic load frames. However, the results of such tests are not accurate. The problem is that during the experiment, the whole machine is not in static equilibrium. The inertial effect influences the experimental data. The records obtained from these machines are often noisy with large oscillation. therefore, the comprehensive review is given to describes the development and evolution of the existing intermediate strain rate testing devices which includes the working principles, some critical theories, technological innovation in load measurement techniques, components of the device, basic technical assumption, and measuring techniques. In addition, some research direction on future implementation and development of an intermediate strain rate apparatus is also discussed in detail.
  • 1.5K
  • 18 Apr 2021
Topic Review
Interstitials in High Entropy Alloys
The effects of interstitials on the mechanical properties of single-phase f.c.c. high entropy alloys (HEAs) have been assessed based on a review of the literature. It is found that in nearly all studies, carbon increases the yield strength, in some cases by more than in traditional alloys. This suggests that carbon can be an excellent way to strengthen HEAs. This strength increase is related to the lattice expansion from the carbon. The effects on other mechanical behavior is mixed. Most studies show a slight reduction in ductility due to carbon, but a few show increases in ductility accompanying the yield strength increase. Similarly, some studies show little or modest increases in work-hardening rate (WHR) due to carbon, whereas a few show a substantial increase. These latter effects are due to changes in deformation mode. For both undoped and carbon doped CoCrFeMnNi, the room temperature ductility decreases slightly with decreasing grain size until ~2-5 µm, below which the ductility appears to decrease rapidly. The room temperature WHR also appears to decrease with decreasing grain size in both undoped and carbon-doped CoCrFeMnNi and in nitrogen-doped medium entropy alloy NiCoCr, and, at least for the undoped HEA, shows a sharp decrease at grain sizes <2 µm. Interestingly, carbon has been shown to almost double the Hall–Petch strengthening in CoCrFeMnNi, suggesting the segregation of carbon to the grain boundaries. There have been few studies on the effects of other interstitials such as boron, nitrogen and hydrogen.
  • 998
  • 06 Nov 2020
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