Function Of Energy Density Research Articles

A new nonlinear vibration model of fiber-reinforced composite thin plate with amplitude-dependent property

In this paper, the material nonlinearity is introduced in the dynamic modeling of fiber-reinforced composite thin plates, and a new nonlinear vibration model of such composite plate structures with amplitude-dependent property is established with the consideration of the nonlinear stiffness and damping characteristics, which is observed and confirmed in the nonlinear vibration characterization experiment. In this new model, the elastic moduli and loss factors are expressed as the function of strain energy density on the basis of Jones–Nelson material nonlinear model. By using the identified parameters under different excitation amplitudes, these elastic moduli and loss factors are characterized as the function of the maximum dimensionless strain energy density. Then, the power function fitting technique is used to determine the nonlinear stiffness and damping parameters in the model, and the nonlinear natural frequencies, vibration responses and damping ratios of a TC300 carbon/epoxy composite thin plate are calculated and measured in a case study. The comparisons between the theoretical and experimental results show that the maximum calculation error of natural frequencies with consideration of amplitude-dependent property is less than 4.3%, and the maximum calculation errors of resonant response and damping results are no more than 12.5 and 9.6% in the 3rd mode and the 6th mode, respectively. Therefore, the practicability and reliability of the proposed model have been verified.

Plasma Oxidation of H2S over Non-stoichiometric LaxMnO3 Perovskite Catalysts in a Dielectric Barrier Discharge Reactor

In this work, plasma-catalytic removal of H2S over LaxMnO3 (x = 0.90, 0.95, 1, 1.05 and 1.10) has been studied in a coaxial dielectric barrier discharge (DBD) reactor. The non-stoichiometric effect of the LaxMnO3 catalysts on the removal of H2S and sulfur balance in the plasma-catalytic process has been investigated as a function of specific energy density (SED). The integration of the plasma with the LaxMnO3 catalysts significantly enhanced the reaction performance compared to the process using plasma alone. The highest H2S removal of 96.4% and sulfur balance of 90.5% were achieved over the La0.90MnO3 catalyst, while the major products included SO2 and SO3. The missing sulfur could be ascribed to the sulfur deposited on the catalyst surfaces. The non-stoichiometric LaxMnO3 catalyst exhibited larger specific surface areas and smaller crystallite sizes compared to the LaMnO3 catalyst. The non-stoichiometric effect changed their redox properties as the decreased La/Mn ratio favored the transformation of Mn3+ to Mn4+, which contributed to the generation of oxygen vacancies on the catalyst surfaces. The XPS and H2-TPR results confirmed that the Mn-rich catalysts showed the higher relative concentration of surface adsorbed oxygen (Oads) and lower reduction temperature compared to LaMnO3 catalyst. The reaction performance of the plasma-catalytic oxidation of H2S is closely related to the relative concentration of Oads formed on the catalyst surfaces and the reducibility of the catalysts.

Composition and Strain Evolution of Undoped Si0.8Ge0.2 Layers Submitted to UV-Nanosecond Laser Annealing

For CMOS scaling beyond 10 nm technology node, high active dopant concentrations in sources and drains are required to minimize contact resistance. Given its ability to reach high temperatures with extremely fast ramps, pulsed laser annealing is used in PMOS and NMOS transistors fabrication to obtain highly doped SiGe:B [1] and Si:P [2] regions. However, there are still few studies on the impact of nanosecond laser annealing on SiGe. We have thus investigated the behavior of thin, pseudomorphic Si0.8Ge0.2 layers submitted to ultraviolet nanosecond laser annealing in a wide range of laser energy densities. Undoped, 30 nm thick pseudomorphic Si0.8Ge0.2 layers were grown at 550°C on (100) Si substrates in a Reduced Pressure CVD reactor. They were subsequently laser annealed in a SCREEN LT-3100 platform operating at 308 nm with a 160 ns pulse duration. The laser energy density was increased from 1.40 up to 2.40 J/cm² in order to investigate various regimes, from SiGe layer sub-melt to a point at which the whole SiGe layer and part of the Si substrate reach the melt. Time Resolved Reflectometry (TRR) and SP2 haze measurements combined with Atomic Force Microscopy (AFM) were used to detect melt threshold and quantify surface roughness evolutions, respectively. High Resolution X-Ray Diffraction and Time-Of-Flight-Secondary Ions Mass Spectrometry characterizations were performed to assess layer composition, strain and crystalline quality as a function of the laser energy density. Melt threshold was detected at 1.55 J/cm² with SP2 Haze measurements (Fig.2) and at 1.58 J/cm² by TRR (Fig. 1). When increasing the laser energy density, three different regimes were identified. In the sub-melt regime, i.e. at energy densities lower than 1.55 J/cm², the annealed samples showed neither surface nor volume differences compared to the as-grown sample. For higher energy densities, part of the Si0.8Ge0.2 layer melted. At first, the melt remained very shallow: TOF-SIMS at 1.59 J/cm² (Fig.3) and Reciprocal Space Map (RSM, not shown here) were identical to those for the reference sample. However, a strong increase in haze and roughness indicated that the surface was modified. For a deeper melt (annealing at 1.8 J/cm²), the germanium was redistributed over the melted depth and segregated towards the surface, creating a top layer with a higher germanium concentration (cf. Fig.3). The solidification and segregation were accompanied by a partial relaxation of the layer up to 25% (the SiGe layer peak in Fig. 4.b is broadened due to mosaicity and not at the same Qx coordinate than that of the Si substrate) while the surface stayed rough. At higher energy density values, for instance 2.0 J/cm² (still in the partial melt regime), germanium segregation still occured and resulted in an even higher germanium concentration near the surface, up to 40%. However, the quality of the layer strongly improved compared to that of the 1.8 J/cm² sample. Roughness and haze were indeed much lower and close to their initial level. The RSM in Fig.4.c indicates that the layer is pseudomorphic, with a rather good crystalline quality, which will be further assessed by TEM observations. This sub-regime with strained SiGe layers exhibiting a high concentration of germanium near the surface could be favorable to the formation of low-resistance contacts in in-situ doped layers [2]. For higher energy densities, the whole SiGe layer and part of the Si substrate were melted: we were then in the full melt regime. For an annealing at 2.4 J/cm², the deeper melt and the intermixing resulted in the formation of a pseudomorphic 85 nm-thick Si0.93 Ge0.07 layer, with an almost uniform germanium profile. The film seems to have a very good crystalline quality as seen in Fig.4.d while RSM, Roughness and haze values were similar to those of the as-grown sample. It is therefore possible, by selecting the appropriate energy densities, to form pseudomorphic SiGe layers with a high germanium content near the surface, which would be favorable for electrical contact formation. Among all the annealing regimes, it seems to be the most promising one for further investigations with doped layers.

Hyperviscoelastic Constitutive Modelling of Solid Propellants with Damage and Compressibility

AbstractFilled elastomers especially composite solid propellants demonstrate strain rate dependent, large deformation/large strain, thermo‐rheological, stress relaxation, stress softening due to microstructural damage and compressible constitutive behavior. This paper presents a micromechanism inspired framework capturing all the above mentioned features by combining both continuum formulation of hyperelasticity, statistical formulation of viscoelasticity, compressibility and damage. The mechanical response is decomposed into equilibrium and time dependent parts. The equilibrium and time dependent parts are further decomposed into dilational and deviatoric parts. Deviatoric parts are modelled using Mooney‐ Rivlin hyperelastic strain energy density functions. Compressibility is modelled by considering dilatational part of strain energy density as the function of the dilation with quadratic and quartic terms. The stress softening during cyclic loading (Mullins effect) due to microstructural damage is described by polynomial function of the current strain energy density and its previous maximum value. The predictions based on the proposed model are in good agreement with the experimental results.

Information-entropic method for studying the stability bound of nonrelativistic polytropic stars within modified gravity theories

We study the stability of nonrelativistic polytropic stars within two modified gravity theories, i.e. beyond Horndeski gravity and Eddington-inspired Born–Infeld theories, using the configuration entropy method. We use the spatially localized bounded function of energy density as solutions from stellar effective equations to construct the corresponding configuration entropy. We use the same argument as the one used by Gleiser and coworkers [M. Gleiser and D. Sowinski, Phys. Lett. B 727 (2013) 272; M. Gleiser and N. Jiang, Phys. Rev. D 92 (2015) 044046] that the stars are stable if there is a peak in configuration entropy as a function of adiabatic index curve. Specifically, the boundary between stable and unstable regions which corresponds to Chandrasekhar stability bound is indicated from the existence of the maximum peak while the most stable polytropic stars are indicated by the minimum peak in the corresponding curve. We have found that the values of critical adiabatic indexes of Chandrasekhar stability bound and the most stable polytropic stars predicted by the nonrelativistic limits of beyond Horndeski gravity and Eddington-inspired Born–Infeld theories are different to those predicted by general relativity where the corresponding differences depend on the free parameters of both theories.

Propagation of Thermo-Elastic Waves at Several Typical Interfaces Based on the Theory of Dipolar Gradient Elasticity

The reflection and transmission properties of thermo-elastic waves at five possible interfaces between two different strain gradient thermo-elastic solids are investigated based on the generalized thermo-elastic theory without energy dissipation (the GN theory). First, the function of free energy density is postulated and the constitutive relations are defined. Then, the temperature field and the displacement field are obtained from the motion equation in the form of displacement and the thermal transport equation without energy dissipation in the strain gradient thermo-elastic solid. Finally, the five types of thermo-elastic interfacial conditions are used to calculate the amplitude ratios of the reflection and transmission waves with respect to the incident wave. Further, the reflection and transmission coefficients in terms of energy flux ratio are calculated and the numerical results are validated by the energy conservation along the normal direction. It is found that there are five types of dispersive waves, namely the coupled longitudinal wave (the CP wave), the coupled thermal wave (the CT wave), the shear wave, and two evanescent waves (the coupled SP wave and SS wave), that become the surface waves at an interface. The mechanical interfacial conditions mainly influence the coupled CP waves, SV waves, and surface waves, while the thermal interfacial conditions mainly influence the coupled CT waves.

Carbon source recovery from excess sludge by mechanical disintegration for biological denitrification.

The goal of the study was to evaluate the possibility of carbon source recovery from excess sludge by mechanical disintegration for biological denitrification. The total efficiency of denitrification, unit demand for organic compounds for denitrification, unit volume of disintegrated sludge and unit cost of nitrogen removal as a function of energy density used for excess sludge disintegration (70, 140 and 210 kJ/L) were analyzed. In the study a full-scale disc disintegrator was used (motor power: 30 kWh, motor speed: 2,950 rpm). It was shown that the amounts of organic compounds released from the activated sludge flocs at all tested levels of energy density are high enough to be used to intensify the removal of nitrogen compounds from wastewater. It was also documented that the energy density provided during process of disintegration was an important factor determining the characteristics of organic compounds obtained under the disintegration for their use in order to intensify the process of denitrification. The highest value of total efficiency of denitrification (50.5 ± 3.1 mg N/L) was obtained for carbon source recovery from excess sludge at 70 kJ/L, but the lowest unit cost of nitrogen removal occurred for 140 kJ/L (0.0019 ± 0.0011 EUR/g N).

Experimental and FE Modeling of Mixed-Mode Crack Initiation Angle in High Density Polyethylene

In this paper, an experimental and a numerical analysis were carried out using High density polyethylene (HDPE). Sheets with an initial central crack (CCT specimens) inclined with a given angle are investigated and compared to the loading direction. The kinking angle is experimentally predicted and numerically evaluated under mixed mode (I+II), as a function of the strain energy density (SED) around the crack-tip, using the Ansys Parametric Design Language (APDL).According to the experimental observations and numerical analysis, the plan of crack propagation is perpendicular to the loading direction. Moreover, as suggested by Sih in the framework of linear elastic fracture mechanics (LEFM), the minimum values Sminof the factor S are reached at the points corresponding to the crack propagation direction. These results suggest that the concept of the strain energy- density factor can be used as an indicator of the crack propagation direction.

A predictive model of rat calorie intake as a function of diet energy density.

Easy access to high-energy food has been linked to high rates of obesity in the world. Understanding the way that access to palatable (high fat or high calorie) food can lead to overconsumption is essential for both preventing and treating obesity. Although the body of studies focused on the effects of high-energy diets is growing, our understanding of how different factors contribute to food choices is not complete. In this study, we present a mathematical model that can predict rat calorie intake to a high-energy diet based on their ingestive behavior to a standard chow diet. Specifically, we propose an equation that describes the relation between the body weight ( W), energy density ( E), time elapsed from the start of diet ( T), and daily calorie intake ( C). We tested our model on two independent data sets. Our results show that the suggested model can predict the calorie intake patterns with high accuracy. Additionally, the only free parameter of our proposed equation (ρ), which is unique to each animal, has a strong correlation with their calorie intake.

Laser modification of graphene oxide layers

The effect of linearly polarized laser irradiation with various energy densities was successfully used for reduction of graphene oxide (GO). The ion beam analytical methods (RBS, ERDA) were used to follow the elemental composition which is expected as the consequence of GO reduction. The chemical composition analysis was accompanied by structural study showing changed functionalities in the irradiated GO foils using spectroscopy techniques including XPS, FTIR and Raman spectroscopy. The AFM was employed to identify the surface morphology and electric properties evolution were subsequently studied using standard two point method measurement. The used analytical methods report on reduction of irradiated graphene oxide on the surface and the decrease of surface resistivity as a growing function of the laser beam energy density.

Reflection and transmission of thermo-elastic waves without energy dissipation at the interface of two dipolar gradient elastic solids.

The reflection and transmission of thermal elastic waves at the interface between two different dipolar gradient elastic solids are studied based on the generalized thermo-elastic theory of Green and Naghdi [(1993). J. Elasticity 31, 189-208] (type II of no energy dissipation). First, some thermodynamic formulas are generalized to a dipolar gradient elastic solid and the function of free energy density is postulated. Second, equations of thermal motion and constitutive relations in a dipolar gradient elasticity are derived. Then the nontraditional interfacial conditions are used to determine the amplitude ratio of the reflection and transmission waves with respect to the incident wave. Some numerical results of the reflection and transmission coefficients in the form of an energy flux ratio are given for different microstructure parameters while thermal parameters are fixed. The numerical results are validated by the consideration of energy conservation. It is found that there are a total of five modes of dispersive waves, namely, coupled MT1 wave, coupled MT2 wave, coupled MT3 wave, SV wave, and one evanescent wave which reduces to the surface waves at an interface, namely, SS wave. The thermal parameters mainly affect the coupled MT2 wave while the microstructure parameters affect not only the coupled waves but also the SS surface waves.

Propagation of thermoelastic waves across an interface with consideration of couple stress and second sound

The reflection and transmission of thermoelastic waves across an interface between two different couple stress solids are studied based on the thermoelastic Green–Naghdi theory with consideration of second sound. First, some thermodynamic equations of a couple stress elastic solid are formulated and the function of free energy density is postulated. Second, equations of thermal motion and heat conduction of the couple stress elasticity are derived and constitutive relations with thermoelastic coupled effects are obtained. From these equations, four kinds of dispersive waves, namely, thermal-mechanically coupled MT1 wave and MT2 wave, uncoupled SV wave, and an evanescent wave that becomes the surface waves at interface, are derived. Then, the interfacial conditions of couple stress elastic solids with consideration of force stress, couple stress, and thermal effects are used to determine the amplitude ratios of the reflection and transmission waves with respect to the incident wave. The numerical results are validated by consideration of energy conservation.

Viscous string cosmological models in alternative theory of gravity

In present communication, the Bianchi type-III, viscous string cosmological models have been investigated in scalar-tensor Brans-Dicke gravity. To obtain an exact solution of the Einstein field equations (EFE), it is assumed that the viscosity is the power function of energy density and the deceleration parameter (DP) as a function of cosmic time with suitable relation i.e. a(t)=[sinh(αt)]1/n , here α,n≠0 are constants. It is observed that the power index has the important significance on the evolution of string cosmological models. It is also noticed that the string tension density (λ) is increasing function of time where as the energy density (ρ) and the cosmological constant (Λ) are decreasing with time and converges to a small value at late time. For better understanding of the model, we have also presented the kinematic and geometric properties of the models.

Stability of spherically symmetric timelike thin-shells in general relativity with a variable equation-of-state

We study spherically symmetric timelike thin-shells in [Formula: see text]-dimensional bulk spacetime with a variable equation-of-state for the fluid presented on the shell. In such a fluid, the angular pressure [Formula: see text] is a function of both surface energy density [Formula: see text] and the radius [Formula: see text] of the thin-shell. Explicit cases of the thin shells connecting two nonidentical cloud of strings spacetimes and a flat Minkowski spacetime to the Schwarzschild metric are investigated.

Ranges of protons in biological targets

Abstract The paper introduces a simple fitting function for quick assessment of proton ranges in biological targets and human tissues. The function has been found by fitting an extensive data set of Monte Carlo proton ranges obtained with the aid of the SRIM-2013 code. The data has been collected for 28 different targets at 8 energies in the interval from 60 MeV to 220 MeV. The paper shows that at a given kinetic proton-beam energy, the Monte Carlo ranges can be satisfactorily fitted by a power function that depends solely on the target density. This is a great advantage for targets, for which the exact chemical composition is not known, or the mean ionizing potential is not reliably known. The satisfactory fit is meant as the fit that stays within the natural range straggling of the Monte Carlo ranges. In the second step, the energy-scaling yielding a universal fitting formula for proton ranges as a function of proton-beam energy and target density is introduced and discussed.

Cathodoluminescence of Y2O3:Eu Thin Films Obtained by RF Sputtering

The cathodoluminescent (CL) properties of Y2O3:Eu thin films obtained by RF magnetron sputtering were investigated. The number of Eu3+ ions in C2 states of lower symmetry was hypothesized to be greater in the film bulk than on the surface based on studies of the CL spectral intensity as a function of the exciting-electron energy and current density. It was shown that film structural defects and the excitation conditions influenced the kinetic characteristics of the red emission of Y2O3:Eu at 612 nm that was due to the electric dipole transition 5D0 –7F2.

Enhanced performance for plasma-catalytic oxidation of ethyl acetate over La1-xCexCoO3+δ catalysts

In this work, plasma-catalytic oxidation of low concentration ethyl acetate (100ppm) over La1-xCexCoO3+δ (x=0, 0.05, 0.1, 0.3 and 0.5) perovskite catalysts was carried out in a coaxial dielectric barrier discharge (DBD) reactor. The effects of Ce-doping on the removal of ethyl acetate and COx (x=1 and 2) selectivity in the plasma-catalytic oxidation process were investigated as a function of specific energy density (SED). Compared to the plasma reaction without a catalyst, the presence of the LaCoO3 catalyst in the plasma enhanced the removal of ethyl acetate and COx selectivity. The use of the Ce-doped catalysts further enhanced the performance of the plasma-catalytic oxidation process. The highest removal efficiency of ethyl acetate (100%) and COx selectivity (91.8%) were achieved in the plasma-catalytic oxidation of ethyl acetate over the La0.9Ce0.1CoO3+δ catalyst at a SED of 558JL−1. The interactions between Ce and LaCoO3 resulted in an increased specific surface area (by 17.1%–68.6%) and a reduced crystallite size (by 13.5%–68.2%) of the Ce-doped LaCoO3 catalysts compared to pure LaCoO3, which favours the oxidation of ethyl acetate in the plasma process. Compared to the LaCoO3 catalyst, the Ce-doped perovskite catalysts showed higher content (maximum 54.9%) of surface adsorbed oxygen (Oads) and better reducibility, both of which significantly contributed to the enhanced oxidation of ethyl acetate and intermediates in the plasma-assisted surface reactions. The coupling of plasma with the Ce-doped catalysts also reduced the formation of by-products including NO2 and N2O. The possible reaction pathways involved in the plasma oxidation process have been discussed.

A plasma-assisted catalytic system for NO removal over CuCe/ZSM-5 catalysts at ambient temperature

A series of CuCe catalysts were prepared by an incipient-wetness impregnation method for selective catalytic reduction of NO in combination with dielectric barrier discharge plasma. The effect of the Cu/Ce mass ratio on NO and NOx (NO+NO2) removal efficiency has been studied as a function of energy density at ambient temperature. The catalyst samples were characterised by BET, XRD, XPS, H2-TPR and NH3-TPD. The results indicated that catalyst addition enhances NO and NOx removal based on only the plasma process. The CuCe catalysts exhibited higher reduction performance compared with the 4wt.% Cu or 4wt.% Ce catalysts, and the catalyst with 4wt.% Cu and 4wt.% Ce showed the best reduction performance with the highest NO and NOx removal efficiencies of 90.7% and 80.1%, respectively, at an energy density of 367J/L. The interactions between Cu and Ce increase oxygen migration to form oxygen vacancies, which facilitates the oxidation of NO to NO2, and NO2 favours NO removal via a fast selective catalytic reduction reaction at low temperature. In addition, the CuCe catalysts exhibited low thermal stability, thereby facilitating the catalytic reduction of NO at ambient temperature.

Reflection and transmission of elastic waves at five types of possible interfaces between two dipolar gradient elastic half-spaces

Reflection and transmission of an incident plane wave at five types of possible interfaces between two dipolar gradient elastic solids are studied in this paper. First, the explicit expressions of monopolar tractions and dipolar tractions are derived from the postulated function of strain energy density. Then, the displacements, the normal derivative of displacements, monopolar tractions, and dipolar tractions are used to create the nontraditional interface conditions. There are five types of possible interfaces based on all possible combinations of the displacements and the normal derivative of displacements. These interfacial conditions with consideration of microstructure effects are used to determine the amplitude ratio of the reflection and transmission waves with respect to the incident wave. Further, the energy ratios of the reflection and transmission waves with respect to the incident wave are calculated. Some numerical results of the reflection and transmission coefficients are given in terms of energy flux ratio for five types of possible interfaces. The influences of the five types of possible interfaces on the energy partition between the refection waves and the transmission waves are discussed, and the concept of double channels of energy transfer is first proposed to explain the different influences of five types of interfaces.

High solids emulsions produced by ultrasound as a function of energy density

The use of emulsifying methods is frequently required before spray drying food ingredients, where using high concentration of solids increases the drying process yield. In this work, we used ultrasound to obtain kinetically stable palm oil-in-water emulsions with 30g solids/100g of emulsion. Sodium caseinate, maltodextrin and dried glucose syrup were used as stabilizing agents. Sonication time of 3, 7 and 11min were evaluated at power of 72, 105 and 148W (which represents 50%, 75% and 100% of power amplitude in relation to the nominal power of the equipment). Energy density required for each assay was calculated. Emulsions were characterized for droplets mean diameter and size distribution, optical microscopy, confocal microscopy, ζ-potential, creaming index (CI) and rheological behavior. Emulsions presented bimodal size distribution, with D[3,2] ranging from 0.7 to 1.4μm and CI between 5% and 12%, being these parameters inversely proportional to sonication time and power, but with a visual kinetically stabilization after the treatment at 148W at 7min sonication. D[3,2] showed to depend of energy density as a power function. Sonication presented as an effective method to be integrated to spray drying when emulsification is needed before the drying process.