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Weyl Semimetals (WSM) for Electronics Applications

Aerospace & Defense Technology: February 2020

  • Magazine Article
  • 20AERP02_11
Published 2020-02-01 by SAE International in United States

New synthesized materials open the way to govern the density of helicity, axial charge, and its flow, axial current.

The major factor determining transport properties of solids is the number of electron states in a vicinity of Fermi level. In equilibrium, no macroscopic flow of electrons exists and, therefore, in order to create such flow, electrons must be excited over their equilibrium distribution. However, electrons with energies well below the Fermi level (compared to the characteristic energy scale kBT, where kB is the Boltzmann constant and T is the temperature), cannot acquire small excitation energy. Indeed, in this case, they would have energy corresponding to already occupied states, which is prohibited by the Pauli principle. In turn, well above the Fermi level, where excitation of electrons is not constrained by the Pauli principle, the electron states are not populated, thus making their contribution to the response negligible.

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Microneedles Extract Fluid for Wearable Sensors

  • Magazine Article
  • TBMG-34916
Published 2019-08-01 by Tech Briefs Media Group in United States

Interstitial fluid is clear, colorless, and similar to blood plasma. Continual sampling of important biomarkers in interstitial fluid could help monitor and diagnose many diseases and disorders. These markers include electrolytes — salts such as potassium and sodium that get out of balance during dehydration; glucose, a sugar that diabetics need to monitor constantly; and lactate, a potential marker of physical exhaustion or life-threatening sepsis.

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Are Internal Diesel Injector Deposits (IDID) Mainly Linked to Biofuel Chemical Composition or/and Engine Operation Condition?

IFP Energies Nouvelles, Institute Carnot-Maira Alves Fortunato, Francis Lenglet, Arij Ben Amara, Laurie Starck
Published 2019-01-15 by SAE International in United States
The increased use of alternative fuels has been linked to performance deterioration of injectors and engines as a result of internal diesel injector deposits (IDID). The present paper investigates fuel composition impact on injector tendency to blockage. Three main areas were investigated : (1) deposits linked to paraffins and aromatics content; (2) deposits linked to biodiesel composition using fatty acid methyl esters (FAME) and hydrotreated vegetal oil (HVO); and (3) deposits linked to the presence of additives (Dodecenylsuccinic anhydride DDSA, Dodecenyl Succinimid DDSI and Sodium Naphthenate). A deposit formation method was developed for the injection bench in order to discriminate the impact of fuels on system performance in terms of fuel volume injected, injection duration and stability. Three operation conditions were tested to represent low, intermediate and high load. In addition, the influence of soaking time and injector heating temperature was evaluated. The nature of the deposit was studied based on its morphology and chemical composition determined using Scanning Electron Microscopy coupled with Energy Dispersive X-ray (SEM/EDX) Spectroscopy. Deposits were observed for all fuels, even…
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Periodic Test for Processing Solutions

AMS B Finishes Processes and Fluids Committee
  • Aerospace Standard
  • ARP4992B
  • Current
Published 2019-01-01 by SAE International in United States
This SAE Aerospace Recommended Practice (ARP) describes a method for classifying the frequencies of analysis of solutions used in the processing of metals, such as electroplating, anodizing, and conversion coating and associated processes but usage is not limited to such applications.
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Enhancement of Thermal Fatigue Strength by the Addition of Calcium to Hypoeutectic Aluminum-Silicon Alloys

Kawasaki Heavy Industries, Ltd.-Kentaro Watanabe, Kojiro Motoyama, Tomokazu Watanabe, Kazuhiro Ishihara, Fujio Maeda
Published 2018-10-30 by SAE International in United States
Several elements affect the structure of eutectic silicon in hypoeutectic aluminum alloys [1, 2, 3, 4]. Among them, calcium has been investigated to a lesser extent compared to the typically used sodium and strontium. In order to enhance the thermal fatigue strength of a small engine, the morphology of eutectic silicon in hypoeutectic aluminum-silicon alloys is controlled by the addition of calcium. In addition, the castability and mechanical properties are investigated. Hence, samples containing different amounts of calcium are prepared at different cooling rates during solidification. The results revealed that, with the increase in the calcium amount and the cooling rate, eutectic silicon exhibits a fine morphology in cross-sectional images. Particularly, with the addition of at least 62 mass ppm of calcium in a specific range of cooling rates, refined eutectic silicon is obtained. In order to clarify additional effects of the added calcium, the amount of dissolved gas, fluidity, and porosity defects are evaluated. The amount of dissolved gas and the fluidity do not change in the range of the investigated calcium amounts. However,…
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Electric double layer capacitors prepared with polyvinyl alcohol and multi-walled carbon nanotubes

Carbon Sci-Tech Labs, School of Electrical and Computer Engi-Carla Giselle Martins Real, Rafael Vicentini, Willian Gonçalves Nunes, Otávio Vilas Boas, Lenon Henrique Costa, Davi Marcelo Soares, Hudson Zanin
Published 2018-09-03 by SAE International in United States
Portable electronics, wearables, electric vehicles and solar cells are sectors in increasingly development which include innovation and miniaturization of the devices. In this scenario, the development of smaller and lightweight energy storage devices, which store more energy, is required. Besides, it is desirable for these devices to be environmentally friendly to minimize pollution. In an attempt to meet these requirements, this work purposes the development and the characterization of nanofibers-based electrode composed of Polyvinyl alcohol (PVA) and multi-walled carbon nanotubes (MWCNT) for electric double layer capacitors (ELCDs) devices with aqueous electrolyte. This composite has been prepared by electrospinning technique and consolidate an electrical conductive and high-surface material electrode. After that, the PVA/MWCNT electrode was assembled in coin cell device with Sodium Sulfate (Na2SO4) electrolyte for electrochemical characterization. The characterization results showed that EDLCs devices present specific capacitance of ∼4.8 Fg-1, energy density of ∼0.1 Wh kg-1, power density of ∼600W kg-, fast charge transfer at electrode/electrolyte interface and high lifetime All these results encourage further development on PVA/MWCNT materials as electrode for EDLCs and Li-Air…
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Sodium Cooling Efficiency in Hollow Valves for Heavy Duty Engines

MAHLE Argentina S.A-Fernando Zenklusen
MAHLE Engine Components USA, Inc.-Marcio Coenca
Published 2018-04-03 by SAE International in United States
As a consequence of the ongoing evolution of engines, where performance is continuously improving and the use of alternative fuels is being adopted by many engine manufacturers, thermal working conditions of the exhaust valves are increasingly critical. In order to better resist the higher temperature levels of the exhaust gases, current development ranges from improvement of the cooling concept for the overall system, new materials for valve set components up to the upgrade of the exhaust manifold material. Change in the design of several valvetrain components due to the increased thermal loads is a logical consequence of this technical evolution process. Hollow exhaust valves filled with Sodium (Na) are a known technology that is widely used in passenger car engines to improve thermal behavior and to avoid the need to change to expensive materials (Ni-base alloys). Nevertheless, shaker-cooling effect of Na for engine speeds below 3.000 [rpm] has been questioned in the past and this technology has not been fully explored in heavy duty (HD) applications [1]. In order to investigate the thermal efficiency or…
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Aluminum as a Fuel

  • Magazine Article
  • TBMG-28719
Published 2018-04-01 by Tech Briefs Media Group in United States

Batteries and combustion engines each have distinctive benefits and limitations. Batteries have simple construction and operate silently; however, their energy density (i.e., the energy per unit volume) is poor, and lithium-ion batteries are potential fire hazards. The energy densities of combustion engines are higher than those of batteries, but combustion engines are relatively loud and emit toxic gases.

Wearable Microneedles

  • Magazine Article
  • TBMG-28538
Published 2018-03-01 by Tech Briefs Media Group in United States

A new painless and minimally invasive microneedle technology can extract large volumes of pure interstitial fluid for further study. Developed at Sandia Labs and the University of New Mexico, the microneedles are a few hairs-breadths wide and can sip the clear fluid between cells in the middle layer of skin. This is below the topmost layer of dead skin cells and above the layer of skin where veins and nerves reside. The clear, colorless fluid is called interstitial fluid and is similar to blood plasma.

Development of Sodium Lidar for Spaceborne Missions

  • Magazine Article
  • TBMG-28318
Published 2018-02-01 by Tech Briefs Media Group in United States

The metal layers at mesospheric altitudes are excellent tracers of neutral atmosphere dynamics, and have been used since the 1960s to study the chemistry and dynamics of the mesosphere. Ablation from meteors is believed to be the chief source of metals such as Na, Mg, K, Fe, and Ca in the middle atmosphere. Due to its relative abundance, large backscatter cross-section, and visible atomic transition, sodium (Na) has been used extensively for lidar studies of the mesosphere.