Average Energy Distribution Research Articles

Sputtering Coefficients of Beryllium and Tungsten by Various Atoms from Hydrogen to Tungsten

Using computer simulation, the sputtering coefficients of Be and W targets, promising materials for the first wall and divertor in the ITER tokamak, are calculated in a wide range of incident atom energies 10–100 000 eV. The following atoms were chosen as projectiles: H, D, T, He, Be, C, N, O, Ne, Ar, W. A strong influence of the surface profile on the results obtained is shown. The limiting cases of a planar potential barrier (smooth surface) and a spherical potential barrier (rough surface) are considered. Data on the average energy and angular distributions of sputtered atoms were obtained, which are necessary for calculating the influx of impurities into the tokamak plasma. The influx of wall material atoms into the ITER tokamak plasma is estimated when the wall is sputtered by flows of fast deuterium and tritium atoms leaving the plasma.

Development and Verification of Sampling Code NECP-SOUL for Evaluated Nuclear Data Files in ENDF-6 Format

A code called NECP-SOUL is developed to generate samples of evaluated nuclear data files in the ENDF-6 format. The motivation for the development is to obtain more accurate uncertainty quantification results based on the covariance data given in evaluated nuclear data files than the sampling method based on multigroup covariances. NECP-SOUL can handle all covariance data in ENDF-6 files, including average fission neutron multiplicities, resonance parameters, cross sections, angular distributions, energy distributions, and cross sections for the production of radioactive nuclides. In this work, samples of ENDF-6 files are input to the nuclear data processing code to generate A Compact ENDF (ACE)-formatted libraries, and these ACE-formatted libraries are used by the Monte Carlo code. Through statistical analysis, the uncertainty of the neutronics results can be obtained. NECP-SOUL is verified against another similar code, SANDY. In addition, the advantage of sampling ENDF-6 files is analyzed by comparing the uncertainty quantification results with those obtained by sampling multigroup covariance matrices. Moreover, the covariances of cross sections and angular distributions newly provided in ENDF/B-VIII.0 are used to analyze their effect on the uncertainty qualification results.

Three-dimensional particle-in-cell simulations of laser-driven multiradiation sources based on double-layer targets.

Double-layer targets (DLTs), made of a low-density foam on top of a solid substrate, can efficiently convert the energy of a high-intensity laser to provide sources of photons and protons. We investigate a 30-fs pulse with a peak intensity of I∼8.7×10^{20}W/cm^{2} and a peak power of ∼120 TW interacting with a DLT using three-dimensional (3D) particle-in-cell simulations. We focus on providing quantitative results in full 3D geometry on the foam thickness dependence; on the competition between two photon-generating processes in DLTs, i.e., nonlinear inverse Compton scattering (NICS) and bremsstrahlung (BS); and on the acceleration of protons via enhanced target-normal sheath acceleration. We discuss conversion efficiency, average energy, and angular distributions of such multiradiation sources. We find that NICS can prevail over BS if the DLT's substrate is thin enough (∼µm) and that the optimal foam thickness that maximizes the conversion efficiency in NICS and BS photons and the proton cutoff energy, among those considered, is the same (15µm). These results show that DLTs constitute an excellent tool for developing relatively compact and optimized laser-driven multicomponent radiation sources.

Analysis of spectral irradiance variation in northern Europe using average photon energy distributions

One major factor affecting the energy yield of photovoltaic modules is the spectral distribution of incident solar radiation. As spectral irradiance data is scarce, this study provides further documentation of recorded spectra at tilt angle 30°– 45°over a period from one to several years, with the resulting distributions of average photon energy (APE) in the 350–1050 nm wavelength range, from five locations in northern Europe. The results show a general trend of higher monthly APE values in summer and lower values in winter, with more pronounced APE variation at increasing latitude. Compared to the reference APE value of 1.88 eV, the largest variation in monthly APE is seen for the northernmost location of Grimstad, Norway, ranging from 1.82 eV to 1.93 eV between January and July with an annual average APE of 1.90 eV. The smallest variation is found for Merklingen, Germany, ranging from 1.86 eV to 1.88 eV between March and July, with an annual average APE of 1.86 eV. Comparing the annual average APE values of the various locations, the study shows a slightly blue-shifted spectrum for Berlin, Enschede and Grimstad, whereas Merklingen experiences a slightly red-shifted spectrum and the APE at Utrecht is similar to the standard reference spectrum. The simulations through SMARTS show air mass, water vapor and aerosols as the major parameters affecting the spectrum. During the winter months, distinct contributions from both clear and cloudy sky conditions result in a bi-modal APE distribution for all locations, which is not observed during the summer months. Analysis of APE demonstrates different site-specific behaviors, even though all sites are categorized in the same Köppen–Geiger (KG) climate class. These differences arise mainly due to atmospheric factors, whereas dissimilarity in albedo conditions, plane of tilt and instrumentation also have some contributions.

Sputtering Yields of Beryllium and Tungsten by Various Atoms from Hydrogen to Tungsten

Sputtering yields of targets made of Be and W, promising materials for the first wall and the divertor of the ITER tokamak, are calculated in a wide range of projectile energies from 10 to 100 000 eV by computer simulation. The following atoms were chosen as bombarding particles: H, D, T, He, Be, C, N, O, Ne, Ar, and W. It is demonstrated that the shape of the surface strongly impacts the obtained results. The limiting cases of a planar potential barrier (a smooth surface) and a spherical potential barrier (a rough surface) are analyzed. The data on the average energy and angular distribution of sputtered atoms needed for calculation of the impurity influx into tokamak plasma are obtained. The influx of atoms of the wall material into the ITER tokamak plasma upon wall sputtering by fluxes of fast deuterium and tritium atoms leaving plasma is estimated.

A unified thermal-field emission theory for metallic nanotips

The role of curvature effects, in the thermal-field (TF) emission of electrons from nanotips, has been investigated. It is found that for field emitter tips having tip radius of curvature Ra<50 nm, the error on using the planar tunneling potential to evaluate the current density is significant compared to the curvature-corrected potential. Furthermore, the error is found to be strongly temperature dependent at low apex fields, whereas at high fields, it is only moderate. For emitter tips having tip radius Ra≥5 nm, a unified expression for current density applicable for field, thermal-field, and thermionic emission is obtained. In the analysis, a single linearization point corresponding to the peak of the normal energy distribution of electrons is chosen, about which the Gamow exponent is expanded. The temperature-dependent curvature-corrected current density equation is numerically validated against a benchmark that performs the current density integral with the Kemble form of the Wentzel–Kramers–Brillouin transmission coefficient up to the peak of the tunneling potential, while above the barrier, the Morse transmission coefficient is used. The agreement is found to be good. It is inferred that the curvature plays a significant role in field and thermal-field emission, whereas in thermionic emission, it is not as important. In the limit where the apex radius of curvature Ra→∞, it is able to retrieve the Murphy–Good equation as well as the Richardson–Laue–Dushman equation in their respective limits.

Multiple pendulum and nonuniform distribution of average kinetic energy.

Multiple pendulums are investigated numerically and analytically to clarify the nonuniformity of average kinetic energies of particles. The nonuniformity is attributed to the system having holonomic constraints and it is consistent with the generalized principle of the equipartition of energy. With the use of explicit expression for Hamiltonian of a multiple pendulum, approximate expressions for temporal and statistical average of kinetic energies are obtained, where the average energies are expressed in terms of masses of particles. In a typical case, the average kinetic energy is large for particles near the end of the pendulum and small for those near the root. Moreover, the exact analytic expressions for the average kinetic energy of the particles are obtained for a double pendulum.

Effect of Circadian Distribution of Energy and Macronutrients on Gestational Weight Gain in Chinese Pregnant Women.

Gestational weight gain (GWG) may be affected by the timing of dietary intake. Previous studies have reported contradictory findings, possibly due to inconsistent characterizations of meal timing. We conducted a birth cohort study in Tianjin to determine the effect of daily energy and macronutrient distribution in mid and late pregnancy on GWG. Dietary intake information in the second and third trimesters used three 24-h dietary recalls, and meal timing was defined in relation to sleep/wake timing. The adequacy of GWG was assessed using recommendations from the Institute of Medicine guidelines. Pregnant women who had a relatively high average energy and macronutrient distribution in the late afternoon-early evening time window exhibited a greater GWG rate and a greater total GWG than that in morning time window during the third trimester (β = 0.707; β = 0.316). Carbohydrate intake in the morning of the second and third trimesters (β = 0.005; β = 0.008) was positively associated with GWG rates. Morning carbohydrate intake in the second trimester was also positively associated with total GWG (β = 0.004). Fat intake in the morning of the third trimester (β = 0.051; β = 0.020) was positively associated with the GWG rates and total GWG. Excessive GWG of Chinese pregnant women was related closely to eating behavior focused on the late afternoon-early evening and carbohydrate and fat intake in the morning during the second and third trimesters.

Fast and accurate determination of the curvature-corrected field emission current

The curvature-corrected field emission current density, obtained by linearizing at or below the Fermi energy, is investigated. Two special cases, corresponding to the peak of normal energy distribution and mean normal energy, are considered. It is found that the current density evaluated using the mean normal energy results in errors in the net emission current below 3% for apex radius of curvature Ra≥5 nm and for apex fields Ea in the range of 3–10 V/nm for an emitter having a work function of ϕ=4.5 eV. An analytical expression for the net field emission current is also obtained for local parabolic tips using the generalized cosine law. The errors are found to be below 6% for Ra≥5 nm over an identical range of apex field strengths. The benchmark current is obtained by numerically integrating the current density over the emitter surface and the current density itself computed by integrating over the energy states using the exact Gamow factor and the Kemble form for the WKB transmission coefficient. The analytical expression results in a remarkable speed-up in the computation of the net emission current and is especially useful for large area field emitters having tens of thousands of emission sites.

Material normal energy distribution for field emission analyses from monocrystalline surfaces

Electron field emission is a complicated phenomenon which is sensitive not only to the particular material under illumination but also to the specific crystalline orientation of the surface. Summarizing the ability for a crystal to emit in a particular direction would be of great use when searching for good field emitters. In this paper we propose a material normal energy distribution which describes the ability of the bound electrons to tunnel under an intense electric field. This framework breaks a computationally expensive 3-D system down to a source distribution representation applicable for more efficient 1-D models. We use the Fowler-Nordheim framework to study the yield and MTE (mean transverse energy) from sources including gold, copper, and tungsten in both monocrystalline and polycrystalline forms. We find an increase in effective work function for field emission in the (111) direction for gold and copper associated with the Bragg plane intersections of the Fermi surface.

Insight into the weak interaction between organic primary amine and propionic acid or phenol solvents in solvent extraction

The essence of solvent extraction is to change the interaction degree between extracted molecules and solvents in the system. The study of solvent extraction at the molecular level has important guiding significance for further design. Here, taking the extraction of organic weak acid (phenol/propionic acid) by primary amines N1923 through hydrogen bond association as an example, the quantitative calculation parameters of reactive molecules were discussed, such as the charge distribution, potential distribution, average local ionization energy (ALIE) distribution and abbreviated Fukui function, while the polar index and polar area percentage were calculated. Moreover, the region and intensity of weak interaction were analyzed and visualized by electronic density difference and Van der Waals (VDW) radius. At the same time, the electron density of the critical point of bond (BCP) and the corresponding predicted value of hydrogen bonding energy are calculated. Finally, the solubility energy of primary amines and the Gibbs free energy of extraction reaction were calculated, and the results show that the interaction between organic amine and propionic acid is stronger by the hydrogen bond mechanism. This study provides a set of systematic cases to analyze the interaction between extraction molecules. It provides a new perspective for understanding the essence of solvent extraction, thus promoting the theoretical development of separation science.

Microscopic reaction mechanism for CO2 gasification of cellulose based on reactive force field molecular dynamics simulations

Gasification is the key process of biomass conversion and utilization, which has been proved to be one of the most promising technologies. In this study, the CO2 gasification process of cellulose was explored by reactive force field molecular dynamics simulations. Firstly, the distribution of average local ionization energy was analyzed. The results showed that the oxygen and hydrogen atoms might be reactive sites. In addition, the product evolution, bond-breaking behavior and carbon conversion during CO2 gasification were investigated. It was found that the bond dissociation energy of glycosidic bond was low and the bond breaking was easy to occur. The CO2 gasification of cellulose was divided into two stages, first the cellulose molecules broke down into small molecular fragments, and then they reacted with CO2. Finally, the effects of CO2/steam ratio and CO2/O2 ratio on the gasification process were analyzed. As the CO2/steam ratio decreased, the H2 yield increased, while the CO yield decreased. With the increase of CO2/O2 ratio, the carbon conversion rate had little change, while the contribution of CO2 gasification to carbon conversion decreased from 99.07% to 50%. The research provides a reference for revealing the microscopic mechanism for CO2 gasification of biomass.

Effect of Charge Transfer and Non-Covalent Interactions of the Synthesized NLO Compound p-Nitrophenol Sodium-Bisulfate Using DFT Method

In the present work a new semiorganic single crystal p-nitrophenol sodium-bisulfate (PNSB) was synthesized and fully characterized by means of single crystal XRD, powder XRD, FT-IR, FT-Raman and UV-visible spectroscopic techniques. The optimized geometrical parameters were obtained at the DFT/B3LYP level of theory and correlate them with similar structures. Normal coordinate analysis, force constants, and potential energy distributions have been used to support the complete vibrational assignments for all vibrational modes. The computed IR and Raman frequencies correlate well with the experiments, as indicated by the correlation factor. The optimized molecular structure reveals the presence of C-H…O hydrogen bonding interaction. The stability of the molecule arising from hyper conjugative interaction and charge delocalization has been analyzed using natural bonding orbital analysis. NBO analysis proved the presence of intermolecular O-H…Na22 hydrogen bonds caused by the interaction of the lone pair of oxygen with the anti-bonding orbital. HOMO, LUMO and ESP analyses were done using DFT, whereas, the absorption band in the UV–vis spectrum was predicted and compared with the experimental data. ESP is used to identify the nucleophilic region, which is located around the sodium atom, and the electrophilic region, which is primarily located at the oxygen atoms of the PNSB molecule. The frontier orbital gap denotes the charge transfer interaction within the compound required for optical activity. Electron Localization Function, Localized Orbital Locator and Reduced Density Gradient analysis were discussed. In order to study the nonlinear optical activity of PNSB, the dipole moment, polarizability and fihyperpolarizabilities were computed. It is found that the calculated first order hyperpolarizability of PNSB is 51.75 times greater than that of urea.

Evaluation of Large-Format Lithium-Ion Cell Thermal Runaway Response Triggered by Nail Penetration using Novel Fractional Thermal Runaway Calorimetry and Gas Collection Methodology

To simultaneously optimize the battery design, reduce risk, and maintain safety margin, it is important to design from the ground up based on test determined cell-specific thermal runaway behavior as a function of heat output and analysis of the expelled gases. These data will inform the analytical models used for design optimization. Here we analyze the thermal runaway behavior of the 134 A-h GS Yuasa Li-ion cell (LSE134) using a novel large format fractional thermal runaway calorimeter and gas collection methodology. Results indicate an average total thermal runaway energy yield of 2.86 MJ, or 1.6 times the stored electrochemical energy; this follows an assertion commonly found in literature that energy yield scales linearly with capacity. The average fractional energy distribution was 2% through the cell body, 53% through the electrode winding, and 45% through the ejecta material and gases. Lot-to-lot variability in heat output was also identified. Additionally, it was found that an average of 416.6 SL of gas was generated which is approximately 3.1 l A-h−1. The exhaust gas was determined to be a mixture of carbon dioxide, methane, ethane, oxygen, hydrogen, and other short chain hydrocarbons. Carbon dioxide was the largest component by volume with a range of 41% to 52% followed by hydrogen which ranged from 28% to 41%. Larger cells appear to result in strong ejecta flow driven events with higher fractions of the total energy delivered via the flow as compared to smaller format Li-ion cells (e.g. 18650 and 21700).

Study on the Variation in Heating Energy Based on Energy Consumption from the District Heating System, Simulations and Pattern Analysis

This study aims to analyze the actual heating energy consumption according to the location and size of apartment houses. The study shows the variation in heating energy consumption in accordance with the living pattern of residents in such apartments. By calculating the average annual heating energy consumption and distribution of the measured heating energy of two years, it was found that the outdoor temperature was inversely proportional to the average heating energy consumption. Moreover, the lowest/highest floors and corner houses were the most vulnerable since they had a lot of area exposed to the outside air and, thus, consume a huge amount of heating energy. According to this study, the heating load had relevance to the factors such as wall loss, window loss, ventilation loss, and solar radiation gain that were analyzed in accordance with the growth in house size. Based on the survey outcome on the living pattern and number of residents, a simulation was conducted to analyze the variation in heating energy consumption. Households consumed the average heating energy for 15.8 h/day and occupied for 16.4 h/day. Households consumed more than the average heating energy for 22.2 h/day and occupied for 21.2 h/day, meaning 6.4 extra hours than those consuming the average heating energy. Households consumed less than the average heating energy for 5.2 h/day and occupied for 10.9 h/day, meaning 10.6 less hours/day than those consuming the average heating energy and 17 less hours/day than those consuming more than the average heating energy.

Co-pyrolytic interactions, kinetics and products of biomass pyrolysis coke and rapeseed cake: Machine learning, DAEM and 2D-COS analysis

In this study, an efficient strategy for synergistic disposal of biomass pyrolysis coke (PC) and rapeseed cake (RC) was proposed to explore their clean utilization, with the purposes for evaluating the co-pyrolytic interactions, kinetics, mechanism and products. The results indicated that synergistic effect was strengthened by lower PC ratio and temperature. A multiple distributed activation energy model (MDAEM) was applied to obtain accurate activation energy distributions. Co-pyrolysis resulted in lower average activation energy and wider distribution, from which the activation energy E0 and σ were in the range of 103.99–214.16 kJ/mol and 3.18–38.09 kJ/mol. MDAEM was also innovatively combined with machine learning to describe and predict co-pyrolysis process, with the determination coefficient R2 beyond 0.999923. Sensitivity analysis and principal component analysis were applied, indicating RC was more sensitive to the heating rate, and preferred dominating reactions at high-temperature region. Temperature dependences of pyrolysates was obtained by two-dimensional correlation spectroscopy method.

Extraction of Energy Characteristics of Blue Whale Vocalizations Based on Empirical Mode Decomposition.

This study extracts the energy characteristic distributions of the intrinsic mode functions (IMFs) and residue functions (RF) for a blue whale sound signal, with empirical mode decomposition (EMD) as the basic theoretical framework. A high-resolution marginal frequency characteristics extraction method, based on EMD with energy density intensity (EDI) parameters for blue B call vocalizations, was proposed. The extraction algorithm included six steps: EMD, energy analysis, marginal frequency (MF) analysis with EDI parameters, feature extraction (FE), classification, and Hilbert spectrum (HS) analysis. The blue whale sound sources were obtained from the website of the Scripps Whale Acoustics Lab of the University of California, San Diego, USA. The source is a type of B call with a time duration of 46.65 s, from which 59 analysis samples with a time duration of 180 ms were taken. The average energy distribution ratios of the IMF1, IMF2, IMF3, IMF4, and RF are 49.06%, 20.58%, 13.51%, 10.94% and 3.84%, respectively. New classification criteria and EDI parameters were proposed to extract the blue whale B call vocalization (BWBCV) characteristics. The analysis results show that the main frequency bands of the signal are distributed at 41–43 Hz in the MF of IMF1 for Class I BWBCV and 11–13 Hz in the MF of IMF2 for Class II BWBCV, respectively.

Pattern Recognition of Growth Characteristics Based on UHF PD Signals of Electrical Tree

In insulation system of power equipment, electrical tree grown under the effect of partial discharges (PD) is one of the main degradation processes leading to failure of high voltage polymeric insulation. PD signals are measured and analyzed for condition monitoring of electrical insulation. In this paper, the combine detection system of Ultra-High Frequency (UHF) PD and electrical tree was used to test PE samples. Based on the energy amplitude variation, the average energy and the average energy distribution of PD signals to identify the growth process of electrical tree, twenty-eight PD characteristic parameters were used as input parameters, such as the energy percentage of 16-layer wavelet decomposition, the wavelet coefficient parameter and the time-frequency domain parameter, which entered the three-layer Back Propagation Neural Network (BPNN) of forty-five hidden neurons, and then the accuracy of pattern recognition during the growth process of electrical tree can reach 99.93% after 5000 steps of training cycle. The consistency of calculation results and experimental results presents that the calculation method can reveal the relationship between PD signals and the growth of electrical tree, which lays the foundation for the process analysis of electrical tree and insulation state monitoring.

Comparative spectral (FT-IR, FT-Raman, UV) investigations, HOMO–LUMO, NBO and in-silico docking analysis of Nikethamide, niazid and 2-Mercaptonicotinic acid

The FT-IR and FT-Raman spectra of N, N-Diethylnicotinamide (ENA), Nicotinic Hydrazide (NHD) and 2-Mercaptonicotinic acid (MNA) were recorded and analyzed experimentally and theoretically. The complete vibrational assignments for all the vibrational modes have been supported by normal coordinate analysis and potential energy distributions. The equilibrium geometry, natural bond orbital calculations and vibrational assignments have been carried out using density functional B3LYP method with the 6–311G++(d,p) basis set. In addition, TD-DFT calculation is initiated to simulate the UV–Vis absorption spectrum and to determine several important electronic properties like HOMO-LUMO gap energy and electronic transitions. In-silico studies have been used to analyze the drug likeness and de-addiction property of the title compounds. The antibacterial activities of the title compounds have been studied via molecular docking and QSAR analysis. Moreover, the title compounds ENA (18.2, 161.9 μm) and NHD (75.11, 54.02 μm) showed a greater inhibiting ability than MNA (80.5, 122.08 μm) when docked against the proteins (PDB ID: 2H29 and 3NM8) and the QSAR analysis proved that the studied compounds have an inhibitor effect against bacterial diseases.

Experimental and calculated infrared spectra of disubstituted naphthoquinones

In recent years there has been interest in incorporating substituted 1,4-naphthoquinones (NQs) into the A1 binding site in photosystem I (PSI) photosynthetic protein complexes. This interest in part stems from the considerably altered bioenergetics of electron transfer that occur in PSI with such substitutions. Time resolved FTIR studies of PSI complexes with disubstituted NQs incorporated have and currently are being undertaken, and with this in mind it is worth considering FTIR absorption spectra of these disubstituted NQs in solution. Here we present FTIR absorbance spectra for 2-bromo-3-methyl-1,4-naphthoquinone (BrMeNQ), 2-chloromethyl-3-methyl-1,4-naphthoquinone (CMMeNQ) and 2-ethylthio-3-methyl-1,4-naphthoquinone (ETMeNQ) in tetrahydrofuran (THF). The FTIR spectra of these di-substituted naphthoquinones (NQs) were compared to FTIR spectra of 2-methyl-3-phytyl-1,4-naphthoquinone [phylloquinone (PhQ)], 2,3-dimethyl-1,4-naphthoquinone (DMNQ), and 2-methyl-1,4-naphthoquinone (2MNQ). To aid in the assignment of bands in the experimental spectra, density functional theory (DFT) based vibrational frequency calculations for all the substituted NQs in solution were undertaken. The calculated and experimental spectra agree well. By calculating normal mode potential energy distributions, unambiguous quantitative band assignments were made. The calculated and experimental spectra together make predictions about what may be observable in time resolved FTIR difference spectra obtained using PSI with the different NQs incorporated. Time resolved FTIR difference spectra are presented that support these predictions.