Simultaneous Energy Conservation Research Articles

Glow discharge excitation and ionization of chromium, comparison with iron

Cr I and Cr II emission spectra from a Grimm-type glow discharge (GD) in argon and neon were analyzed. Intensities of strong resonance Cr I lines were corrected for self-absorption and population functions (experimental Boltzmann plots) of the Cr I system were established. A prevailing excitation mechanism in Cr I is the electron impact (EI) excitation. Cr II spectra in both discharges were described by transition rate (TR) diagrams, under the model of radiatively-dominated deexcitation. The contribution of cascade excitation was subtracted and the resulting net-TR diagrams of Cr II were analyzed. Unlike ionic spectra of some other transition elements, asymmetric charge transfer (ACT) between the ions of the discharge gas and ground state Cr atoms does not play a role in the excitation of the Cr II spectrum, because of the absence of suitable states in Cr II that would allow simultaneous conservation of energy and total angular momentum. Cr II states below ≈17 eV are populated largely by EI excitation from long-lived low Cr II states. In a neon discharge, ACT reactions between neutral neon metastables and doubly charged Cr ions and between neutral chromium and neon molecular ions were identified. The findings reported here were compared with the excitation of Fe I and Fe II systems at similar conditions. A well-known ‘hydrogen effect’, an enhancement of the Cr II line at 267.7165 nm in the presence of hydrogen in a GD plasma, was explained by charge transfer reaction between H+ ions and neutral chromium.

Impact of Mismatch Angle on Electronic Transport Across Grain Boundaries and Interfaces in 2D Materials

We study the impact of grain boundaries (GB) and misorientation angles between grains on electronic transport in 2-dimensional materials. Here we have developed a numerical model based on the first-principles electronic bandstructure calculations in conjunction with a method which computes electron transmission coefficients from simultaneous conservation of energy and momentum at the interface to essentially evaluate GB/interface resistance in a Landauer formalism. We find that the resistance across graphene GBs vary over a wide range depending on misorientation angles and type of GBs, starting from 53 Ω μm for low-mismatch angles in twin (symmetric) GBs to about 1020 Ω μm for 21° mismatch in tilt (asymmetric) GBs. On the other hand, misorientation angles have weak influence on the resistance across MoS2 GBs, ranging from about 130 Ω μm for low mismatch angles to about 6000 Ω μm for 21°. The interface resistance across graphene-MoS2 heterojunctions also exhibits a strong dependence on misorientation angles with resistance values ranging from about 100 Ω μm for low-mismatch angles in Class-I (symmetric) interfaces to 1015 Ω μm for 14° mismatch in Class-II (asymmetric) interfaces. Overall, symmetric homo/heterojunctions exhibit a weak dependence on misorientation angles, while in MoS2 both symmetric and asymmetric GBs show a gradual dependence on mismatch angles.

Guiding optical modes in chains of dielectric particles

We have investigated low frequency guiding polariton modes in finite linear chains of closely packed dielectric spherical particles of different optical materials. These guiding (chain bound) modes cannot decay radiatively, because photon emission cannot take place with simultaneous conservation of energy and momentum. For extending previous work on infinite chains of spherical particles [1] and infinite rods [2, 3], we were able to apply the multisphere Mie scattering formalism to finite chains of dielectric particles to calculate quality factors of most bound modes originating from the first two Mie resonances depending on the number of particles N and the material's refractive index nr. We found that, in agreement with the earlier work [4], guiding modes exist for n(r) > 2 and the quality factor of the most bound mode scales by N(3). We interpreted this behavior as the property of "frozen" modes near the edges of guiding bands with group velocity vanishing as N increases. In contrast with circular arrays, longitudinal guiding modes in particle chains possess a higher quality factor compared to the transverse ones.

Artificial Intelligence in Buildings: A Review of the Application of Fuzzy Logic

A review of fuzzy logic applications to buildings research is the topic of this paper. Emphasis is given to the applications that deal with the regulation and modelling of indoor thermal comfort, visual comfort and indoor air quality. The improvement of indoor comfort with simultaneous energy conservation is considered. Heating, ventilation and air-conditioning (HVAC) systems operation, fault diagnosis and their modelling by fuzzy logic for prediction of their behaviour is also investigated. Significant attention is provided to the regulation of the indoor environment by taking into account the combining effect of all comfort aspects.

Poisson-Bracket Approach to the Construction of Energy- and Potential-Enstrophy-Conserving Algorithms for the Shallow-Water Equations

Abstract Arakawa and Lamb discovered a finite-difference approximation to the shallow-water equations that exactly conserves finite-difference approximations to the energy and potential enstrophy of the fluid. The Arakawa– Lamb (AL) algorithm is a stunning and important achievement—stunning, because in the shallow-water case, neither energy nor potential enstrophy is a simple quadratic, and important because the simultaneous conservation of energy and potential enstrophy is known to prevent the spurious cascade of energy to high wavenumbers. However, the method followed by AL is somewhat ad hoc, and it is difficult to see how it might be generalized to other systems. In this paper, the AL algorithm is rederived and greatly generalized in a way that should permit still further generalizations. Beginning with the Hamiltonian formulation of shallow-water dynamics, its two essential ingredients—the Hamiltonian functional and the Poisson-bracket operator—are replaced by finite-difference approximations that ma...

On the dual cascade in two-dimensional turbulence

We study the dual-cascade scenario for two-dimensional (2D) turbulence driven by a spectrally localized forcing applied over a finite wavenumber range [ k min, k max] (with k min>0) such that the respective energy and enstrophy injection rates ϵ and η satisfy k min 2 ϵ≤ η≤ k max 2 ϵ. The classical Kraichnan–Leith–Batchelor paradigm, based on the simultaneous conservation of energy and enstrophy and the scale-selectivity of the molecular viscosity, requires that the domain be unbounded in both directions. For 2D turbulence either in a doubly periodic domain or in an unbounded channel with a periodic boundary condition in the across-channel direction, a direct enstrophy cascade is not possible. In the usual case where the forcing wavenumber is no greater than the geometric mean of the integral and dissipation wavenumbers, constant spectral slopes must satisfy β>5 and α+ β≥8, where − α (− β) is the asymptotic slope of the range of wavenumbers lower (higher) than the forcing wavenumber. The influence of a large-scale dissipation on the realizability of a dual cascade is analysed. We discuss the consequences for numerical simulations attempting to mimic the classical unbounded picture in a bounded domain.

00/02194 method for reducing nitrogen oxides in combustion units under simultaneous energy conservation

00/02194 method for reducing nitrogen oxides in combustion units under simultaneous energy conservation

Primary photochemical and photophysical processes in chloro- and bromo-acetylene

Measurements of the fluorescence lifetimes and quantum yields of fluorescence from selected individual vibronic states of chloro- and bromo-acetylene are reported and the data analyzed in terms of the coupling of photon emission to the photodissociation reaction HCCX → HCC·(2Π)+ X·(2P) where X = Cl, Br. It is suggested that the reaction involves a slow internal conversion from the first excited singlet state to the ground electronic state, and that vibrational relaxation in the ground electronic state is sufficiently slow that randomization of the excitation energy does not occur before dissociation. Consequent competition between vibrational relaxation and resonance amongst quasi isolated groups of states leads to a departure from RRKM type behaviour.An unusual variation with energy of the nonradiative lifetimes of vibronic states is found. This observation is interpreted by taking note of the constraints imposed on the dissociation rate by the simultaneous conservation of energy, linear and angular momentum.The i.-r. and u.-v. spectra of chloro- and bromo-acetylene are re-investigated and differences between our findings and those of others are discussed in terms of the electronic structure of these molecules.