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AlGaN/GaN HEMT Modeling and Simulation
Published in D. Nirmal, J. Ajayan, Handbook for III-V High Electron Mobility Transistor Technologies, 2019
Figure 10.2 shows a heterojunction formed by the junction of narrow band gap (GaN) and wide band gap (AlxGa(1−x)N) semiconductors. Electrons in general have potential and kinetic energy. The potential energy is because of the electrostatic field in the nuclei. Free electron level or vacuum level is the position with zero kinetic energy. Nuclei have positive charge by which it attracts the negative charged electrons to the nuclei. The positive energy means free particle with certain kinetic energy, whereas negative energy presents particles at certain energy level of the atom. Certain energy is required to remove the electron from the nuclei. It is a minimum distance where there is no attractive force between the electrons and the nuclei of the material once it is pulled out of the material. The distance is denoted as vacuum level. The amount of energy required to pull the electron from Fermi level to vacuum level is called work function (ϕ), and energy to pull the electron from conduction band to vacuum level is denoted as electron affinity (χ).
The Ginzburg-Landau Equations and Their Extensions
Published in R. D. Parks, Superconductivity, 2018
We thus arrive at a physical interpretation for Eq. (114) which is quite similar to that given earlier for the phenomenological Ginzburg–Landau free energy functional. Again there are essentially four contributions to Fs − Fn: a negative energy of pairing correlation, a positive superfluid kinetic energy, a positive “quantum-mechanical pressure” arising from spatial variations in ∣Δ∣, and a positive magnetic field exclusion energy. The important generalization here, however, is that each of these contributions is assigned its value as calculated in the BCS theory, but with ΔT everywhere replaced by the local value Δ(r). In other words, the slow variation approximation has led to a picture very close to a two-fluid model, in which each small element of superfluid is in local equilibrium and described by a local BCS theory.
Dynamic stability of non-conservative systems
Published in Kurt Ingerle, Non-Conservative Systems, 2018
To promote the understanding of the later made statements about the moving behavior of non-conservative systems, the differences between conservative and non-conservative dynamic responses will be compared. For this purpose clamped free column will be used loaded at its tip by a conservative and tangential load. The following energy quantities need to be considered:system: the elastic deformation is capable to store (negative energy) and to provide energy (positive energy, transfered to kinetic energy).forces: forces might perform positive and negative energy, i.e. introduce and extract energy.mass: increasing and decreasing kinetic energy consumes and supplies energy.damping: dissipates energy to non-mechanical form (heat).disturbance is of finite size an affects the potential energy of the system.
The one-dimensional hydrogenic impurity states confined at one end of the InAs quantum well
Published in Philosophical Magazine, 2022
De-hua Wang, Xue He, Xue Liu, Bin-hua Chu, Wei Liu, Meng-meng Jiao
Since the motion of the electron is confined in a quantum well, the walls of the quantum well will put a pressure on the atomic electron. As a consequence, the energy of the electron can be positive, negative or zero in contrast to the negative energy for the free hydrogenic atom. Therefore, we solve the above Schrodinger equation (Equation (3)) for three different cases. Negative-energy case, E < 0. Set , where . Then Equation (3) becomes: where .The above equation is a Whittaker equation, with the solution as: here is the Kummer function.
Substituted hydrocarbon: a CCSD(T) and local vibrational mode investigation
Published in Molecular Physics, 2021
Alexis Antoinette Ann Delgado, Daniel Sethio, Devin Matthews, Vytor Oliveira, Elfi Kraka
Natural population charges of CCSD(T) were obtained from the natural bond orbital (NBO) analysis [100,101] with the NBO6 program [102]. Using the AIMAll program, electron density and energy density values at C≡C, C=C, and C−C bond critical points (BCP), from CCSD(T), were determined [103]. The Cremer–Kraka criterion was used to distinguish bond nature of C≡C, C=C, and C−C bonds where covalent bonding is represented by negative energy density values ( < 0) and electrostatic interactions are denoted by positive energy density values ( > 0) [69,72,104].
Energy expenditure and dietary intake in professional football players in the Dutch Premier League: Implications for nutritional counselling
Published in Journal of Sports Sciences, 2019
Naomi Y.J. Brinkmans, Nick Iedema, Guy Plasqui, Loek Wouters, Wim H.M. Saris, Luc J.C. van Loon, Jan-Willem van Dijk
In the present study, the weighted daily EI (11.1 ± 2.9 MJ (2658 ± 693 kcal)) assessed by face-to-face 24h recalls was 18 ± 15% lower than the daily EE (13.8 ± 1.5 MJ (3285 ± 354 kcal)) measured by DLW. Although this finding suggests a negative energy balance, it should be noted that the body mass of the football players remained stable over the 14d assessment period. Therefore, the EI assessment was likely subjected to underreporting, rather than undereating. This is not surprising, as underreporting is a common phenomenon in nutrition research (Black et al., 1993; Hebert et al., 2014). The 18 ± 15% underreporting of EI observed in the present study is in close agreement with other studies in elite athletes that validated EI against the DLW method. In this regard, Capling et al. (2017) recently reported an average under-estimation of 19% in eleven studies comparing self-reported EI to EE measured by the DLW-method. It should be noted that the underreporting may be partly explained by selective underreporting of undesirable and/or energy dense food (Magkos & Yannakoulia, 2003), which may potentially lead to greater underreporting of carbohydrate and fat compared with protein intake.