Change In Internal Energy Research Articles

The receding contact line cools down during dynamic wetting.

When a contact line (CL)-where a liquid-vapor interface meets a substrate-is put into motion, it is well known that the contact angle differs between advancing and receding CLs. Using non-equilibrium molecular dynamics simulations, we reveal another intriguing distinction between advancing and receding CLs: while temperature increases at an advancing CL-as expected from viscous dissipation, we show that temperature can drop at a receding CL. Detailed quantitative analysis based on the macroscopic energy balance around the dynamic CL showed that the internal energy change of the fluid due to the change of the potential field along the pathline out of the solid-liquid interface induced a remarkable temperature drop around the receding CL, in a manner similar to latent heat upon phase changes. This result provides new insights for modeling the dynamic CL, and the framework for heat transport analysis introduced here can be applied to a wide range of nanofluidic systems.

Thermo-Structure Approach to Dissimilar Explosive Cladding with Interlayer

A thermodynamic model capable of predicting the change in internal energy, work done, and thermal energy required during aluminum-stainless steel explosive cladding is presented. The mathematical model is instrumental in determining the temperature and pressure developed at the interface, which characterizes the interface microstructure, compared with the numerical simulation. Numerical simulation is implemented by the Smoothed Particle Hydrodynamics method available in ANSYS Autodyn. Furthermore, the effect of different interlayers, such as Al 1100, copper, and SS 304, on kinetic energy utilization and deformation work is discussed. The increase in ram tensile and shear strengths is also reported.

Multiscale molecular simulations on the rejuvenation of recycled asphalt mixture: An insight into molecular impact of rejuvenators in aged asphalt binders

Asphalt rejuvenation technology is an effective method to recycle reclaimed asphalt pavement (RAP) for the production of high-quality recycled asphalt mixtures. This approach contributes to mitigating environmental pollution and facilitating resource recycling. In this study, the impact of rejuvenator molecules on the rejuvenation process was explored by utilizing theoretical models and dynamics simulations. Free volume theory models were used to calculate the diffusion coefficient, while molecular dynamics (MD) simulations revealed the internal energy changes during diffusion. Molecules with high interaction with aged asphalt are easier to reach the homogeneous state in diffusion systems under higher temperatures. The quantification of blending by Fick's 2nd law suggests that the blending process consists of three stages: an intense diffusion phase, a stabilization phase, and a homogeneous state phase. The time taken to reach the homogeneous stage depends on the chemical structure of the rejuvenators and the temperature. This study elucidates the molecular-scale mechanism of RAP rejuvenation and provides a roadmap for improving environmentally friendly RAP rejuvenation technology.

Dielectrically driven thermodynamic state functions discriminating bone marrow response for two radiation dose rates

Measuring irradiation impact of different dose rates is rather difficult. This work introduces physical parameters can measure and discriminate these effects. Since ionising radiation makes electrical inhomogeneity through ionisation within the irradiated medium, the thermodynamic functions derived from dielectric parameters can be used to achieve this purpose. Promising results discriminating dose rates were obtained, Helmholtz free energy showed elevation that is proportional to dose rate. Where changes in entropy, internal energy, enthalpy and activation energy displayed contradicted behaviour between the, relatively, lower and higher dose rates used in the study. Therefore, the use of these revisited physics parameters succeeded in discriminating the effects of two different dose rates, allowing the ability of proper medical intervention at the physical changes’ stage, which is rather early before late effects as biochemical or biological changes occur. This constructs a step forward to enable prevention of most of such late effects as possible.

Oxygen isotope effect in VO2

We investigate the oxygen isotope effect on the ${\mathrm{VO}}_{2}$ metal-insulator transition. Using an alternative method, we synthesize ${\mathrm{V}}^{16}\phantom{\rule{0.16em}{0ex}}{\mathrm{O}}_{2}$ and ${\mathrm{V}}^{18}\phantom{\rule{0.16em}{0ex}}{\mathrm{O}}_{2}$ crystals, finding a 1%--3% phonon softening and a 1.3 K increase in the metal-insulator transition temperature for the latter. A simple calculation, further confirmed by density functional theory, shows that this shift can be attributed to changes in the lattice internal energy. Our results show that lattice dynamics plays a key role in setting the electronic transition temperature, indicating that electronic and structural degrees of freedom remain strongly coupled at the transition.

Study on mechanical properties and energy change of rock materials in whole splitting process based on peridynamics

Aiming to bypass the inability to directly observe the evolution process of rock internal deformation and fracture, this paper proposes that rock samples with different inclination angles can be analyzed from the standpoint of energy, using the bond-base peridynamic theory and the PMB model of brittle materials, combined with laboratory experiments. The whole process of shearing is analyzed, and the LAMMPS software is used to simulate the internal energy change of rock-like materials under shear conditions, while the damage evolution law of samples with different dip angles is studied from macro and micro perspectives. The result shows that prefabricated cracks and the inclination of cracks are important factors for specimen damage, a finding that has important theoretical value for rock mechanics research. The research results can reduce the occurrence of rock burst accidents, the difficulty of mine support, and the cost of mining engineering, as well as improve mine safety levels.

Quantifying Energy Conversion in Higher-Order Phase Space Density Moments in Plasmas.

Weakly collisional and collisionless plasmas are typically far from local thermodynamic equilibrium (LTE), and understanding energy conversion in such systems is a forefront research problem. The standard approach is to investigate changes in internal (thermal) energy and density, but this omits energy conversion that changes any higher-order moments of the phase space density. In this Letter, we calculate from first principles the energy conversion associated with all higher moments of the phase space density for systems not in LTE. Particle-in-cell simulations of collisionless magnetic reconnection reveal that energy conversion associated with higher-order moments can be locally significant. The results may be useful in numerous plasma settings, such as reconnection, turbulence, shocks, and wave-particle interactions in heliospheric, planetary, and astrophysical plasmas.

A nonlinear creep model for surrounding rocks of tunnels based on kinetic energy theorem

The initiating condition for the accelerated creep of rocks has caused difficulty in analyzing the whole creep process. Moreover, the existing Nishihara model has evident shortcomings in describing the accelerated creep characteristics of the viscoplastic stage from the perspective of internal energy to analyze the mechanism of rock creep failure and determine the threshold of accelerated creep initiation. Based on the kinetic energy theorem, Perzyna viscoplastic theory, and the Nishihara model, a unified creep constitutive model that can describe the whole process of decaying creep, stable creep, and accelerated creep is established. Results reveal that the energy consumption and creep damage in the process of creep loading mainly come from the internal energy changes of geotechnical materials. The established creep model can not only describe the viscoelastic–plastic creep characteristics of rock, but also reflect the relationship between rock energy and creep deformation change. In addition, the research results provide a new method for determining the critical point of creep deformation and a new idea for studying the creep model and creep mechanical properties.

Confirmation of the First Law of Thermodynamics in Theory and Extended Bernoulli Equation

The internal energy change of ideal gas does not depend on the volume and pressure. The internal energy change of real gas has not any relation with the volume and pressure, which had been proved. If the internal energy change had not any relation with the volume and pressure, we could confirm the first law of thermodynamics in theory. Simultaneously, the internal energy change is the state function that shall be able to be proved in theory. If the internal energy change depended on the volume and pressure, we could not prove that the internal energy change is the state function and the chemical thermodynamics theory is right. The extended or modified Bernoulli equation can be derived from the energy conservation law, and the internal energy change, heat, and friction are all considered in the derivation procedure. The extended Bernoulli equation could be applied to the flying aircraft and mechanical motion on the gravitational field, for instance, the rocket and airplane and so on. This paper also revises some wrong ideas, viewpoints, or concepts about the thermodynamics theory and Bernoulli equation.

ШТОРМОВОЙ ЦИКЛОГЕНЕЗ НАД ЯПОНСКИМ МОРЕМ 16-18 ЯНВАРЯ 2016 Г.: АНАЛИЗ ЭНЕРГИИ И ВЗАИМОДЕЙСТВИЯ ВИХРЕЙ

The paper presents the results of studying the conversion of various types of energy, taking into account the formation and dissipation of a warm core in the central part of cyclones. The contribution of energy types (kinetic, potential, and internal) and their impact on the intensity of the cyclone development were also assessed by the example of the evolution of a mesocyclone. The mesocyclone was generated on the periphery of the main subtropical cyclone in January 2016 over the Sea of Japan and caused heavy precipitation and strong winds on the southern coast of the Primorsky krai. It is shown for each of the two analyzed cyclones that the stage of their deepening is accompanied by the formation of the warm core with a simultaneous decrease in the bulk values of all potential energy indicators for the vortex in the central region. At the stage of dissipation of the warm core, the values of all potential energy indicators increase. A change in water vapor reserves in the central part of both cyclones is similar to a change in internal energy, which is associated with the transformation of water vapor in the atmosphere (forced and free convection).

Theoretical prediction by DFT on properties of β′-SrTa2O6 crystal

Based on the Density Functional Theory (DFT) electronic band structure, state density, linear optics, elastic, dynamic and thermodynamic properties of ??-SrTa2O6 crystal with P4/mbm (No. 127) space group were investigated with the help of ABINIT and Wien2k code. In the study, it was found that the ??-SrTa2O6 crystal is classified as a semiconductor with an indirect bandgap. For this crystal, the dielectric function was obtained and optical constants such as energy loss function, extinction coefficient, absorption coefficient and reflectivity were calculated. The components of the elastic stiffness tensor, the phonon dispersion, the state density and the contribution of each atom to the state density were obtained. Finally, thermodynamic properties were determined for the ??-SrTa2O6 crystal. Furthermore, the changes in free energy (F), internal energy (E), entropy (S) and heat capacity (C) depending on the temperature were investigated.

Energy and exergy analysis of an experimental ventilated façade

This work, analyzes ventilated façades through the first and second law of thermodynamics. In addition to the energy-balances, it presents the exergy-balances on the interior and exterior surface of a façade, taking into account the different mechanisms of heat exchange. It proposes two new indexes (EQC and ExQC) to characterize the behavior of ventilated façades, by comparing their behavior with a reference façade and considering the energy balance in one case and the exergy balance in the other. An experimental test of a forced ventilated façade serves as the case study, using the test-methodology based on Paslink cells. The test data serve to characterize the behavior of the façade, both from an energy and exergy point of view. Overall, 53.05 kWh of heat is lost to the outside through the façade during 6 days of November, which corresponds to 0.31 kWh of exergy-loss. The internal energy change of the façade is decomposed according to its layers, showing that in terms of energy the sandwich insulation layer influences the most (99.45 % of the total change) but in terms of exergy, on the contrary, the metal sheet affects the most (83.66 %). The values obtained for the two indexes show that, under the test conditions, although the ventilated façade and the reference façade present similar values from the energy point of view, when the exergy is used, it is clearly seen that the behavior of the ventilated façade is 44 % better.

Connections between efficient control and spontaneous transitions in an Ising model.

A system can be driven between metastable configurations by a time-dependent driving protocol, which uses external control parameters to change the potential energy of the system. Here we investigate the correspondence between driving protocols that are designed to minimize work and the spontaneous transition paths of the system in the absence of driving. We study the spin-inversion reaction in a 2D Ising model, quantifying the timing of each spin flip and heat flow to the system during both a minimum-work protocol and a spontaneous transition. The general order of spin flips during the transition mechanism is preserved between the processes, despite the coarseness of control parameters that are unable to reproduce more detailed features of the spontaneous mechanism. Additionally, external control parameters provide energy to each system component to compensate changes in internal energy, showing how control parameters are tuned during a minimum-work protocol to counteract underlying energetic features. This paper supports a correspondence between minimum-work protocols and spontaneous transition mechanisms.

Investigation of the thermal and ferroelectric properties of a Spin-1 Ising thin film: Insight from path integral Monte Carlo

In this work, we provide an analysis of the thermal and ferroelectric properties of an Ising thin film in a transverse field extended for a higher spin (σ=1) within the Quantum Monte Carlo method. For this purpose, several underlying physical quantities were examined in detail including the longitudinal polarization, pyroelectric coefficient, internal energy, and entropy change. This work unravels also a particular contribution of the transverse field Ω/J and surface coupling Js/J on the aforementioned physical quantities, which have significant implication on the phase transition temperature Tc. The polarization values are kept almost unchanged at a low temperature. Furthermore, the peaks corresponding to the entropy change ΔS are broad, and usually occur in a narrow temperature at their corresponding Tc, and result an enlargement of their magnitude upon increasing the external electric field and ultimately their maxima. Meanwhile, a change regarding the interfacial coupling Jint does not significantly affect ΔS and thus Tc. A typical hysteresis behavior is observed to confirm the ferroelectric–paraelectric phase transition.

A GPU-based 2D viscous flow model with variable density and heat exchange

Numerical simulation of unsteady viscous flow over variable topography under the influence of temperature changes is a challenge. In order to apply the model to large domains with complex topography, it becomes mandatory to reduce the model complexity from 3D to 2D by depth averaging the equations and to apply massive parallelization techniques for an efficient simulation. The depth averaged mass continuity, momentum and internal energy equations, combined with suitable friction laws, can be used for this type of flows. Variations in temperature can be accounted for from internal energy changes with density changing accordingly. The resulting system is solved using a finite volume technique on unstructured triangular grids well suited for problems over variable topography. A generic model applicable to a wide range of viscous fluids and validated with synthetic cases is presented to evaluate the performance of the numerical solution in presence of both external thermal forcing functions and discontinuous initial conditions. Finally, the model is applied to a realistic application and calibration to a particular case of lava flow taking into consideration variable density, viscosity and yield stress with temperature . A heat transfer with the air is included to consider the lava cooling. The numerical results of the lava front advance are compared to the Copernicus satellite observations at different dates. The efficiency of the GPU implementation allows to simulate a 11 day event in less than 1.7 h of simulation.

A new method for wear estimation of TBM disc cutter based on energy analysis

The accurate estimation of disc cutter wear has always been a long-term topic affecting the excavation efficiency and construction cost of tunnel boring machines (TBMs), especially in the project of high-strength and high-abrasiveness stratum. In fact, disc cutter wear is one of the comprehensive results of rock-machine interaction during TBM excavation. Therefore, the change of internal energy of rock-machine system describes the wear information of disc cutter. In this study, a new method for estimation disc cutter wear based on energy conversion mechanism is proposed. Firstly, the basic relationship of energy conversion during TBM excavation is analyzed in detail, and an energy equation considering the influence of geological conditions, TBM technical specifications and rock-machine interactions at three levels is established. Based on this context, according to the working characteristics and abrasion mechanism of disc cutter, the conversion mechanism between the disc cutter wear energy and wear capacity is investigated, and the definite relationship between the energy conversion coefficient and the properties of intact rock is obtained. Furthermore, to illustrate the applicability of this method, a case study of the Shenzhen Metro Project in China is introduced and analyzed in detail. The results show that the proposed method can predict 85 % of the average wear of each disc cutter on the cutterhead. Finally, the prediction method provided in this study is compared with Gehring, NTNU and CSM models to validate the rationality and reliability of this method. Evidently, this method can provide an accurate and reliable estimate of the general wear capacity and life of disc cutters on the cutterhead, and it is also a very practical tool for TBM engineers to make decision and optimize the cutter replacement scheme.

Evaluation of path-dependent work and internal energy change for hysteretic mechanical systems

The accuracy of procedures for the analysis and design of hysteretic mechanical systems, in which both generalized rate-dependent and rate-independent hysteretic forces have a non-conservative nature, can be significantly improved by a straightforward computation of work and energy terms. Thus, with the aim of shedding light on the definition and evaluation of work and energy components, we first derive the nonlinear equilibrium equations of a conventional family of MDOF hysteretic mechanical systems and, subsequently, we introduce the modified work-energy theorem. In addition, to allow for a forthright evaluation of path-dependent work and internal energy change associated with generalized rate-dependent (rate-independent) hysteretic forces, we derive the related (closed form) expressions by adopting the Seleemah and Constantinou (Vaiana and Rosati) model. The former is capable of simulating both linear and nonlinear rate-dependent hysteretic responses; the latter can simulate a great variety of rate-independent hysteretic behavior, characterized by symmetric, asymmetric, pinched, S-shaped, flag-shaped hysteresis loops or by an arbitrary combination of them. Finally, several nonlinear dynamic analyses are performed on a MDOF hysteretic mechanical system to clearly describe its free vibration and forced harmonic vibration responses in terms of work and energy quantities.

Statistical Chemical Thermodynamics and Energetic Behavior of Counting: Gibbs' Theory Revisited.

One of the major tenets of Gibbs' equilibrium chemical thermodynamics is "counting the number of particles" and introducing the associated chemical potential. This leads to the concept of chemical energy μdN that becomes a part of the total internal energy change in Gibbs' fundamental thermodynamic relation. However, a pure thermomechanical description of a particle system has only two fundamental forms of energy, namely, mechanical work and heat; Gibbs' μ is an emergent concept. Following this perspective, we present an alternative, generalized Gibbs formalism that serves as a statistical theory of emergence: chemical potential is introduced down to the level of individual meso- or even microstates of a system. The research practice in biophysical chemistry since the 1950s epitomizes this perspective, in which the concept of potential of mean force, or conditional free energy, plays a central role. Our theory suggests a generalized "energetic representation" for scientific data that is in the form of counting frequency, which is measured routinely through equilibrium constants in chemistry laboratories.

Adsorption thermodynamics of CO2 on nitrogen‐doped biochar synthesized with moderate temperature ionic liquid

AbstractThe purpose of this work was to investigate the thermodynamic characteristics of carbon dioxide (CO2) adsorption on a promising nitrogen‐doped biochar at constant temperature and isopiestic pressure. The biochar was prepared as a CO2 adsorbent based on catalytic pyrolysis of pristine coconut shells using urea as the nitrogen source and moderate temperature ionic liquid as a catalyst. The results showed that CO2 adsorption on the biochar was a spontaneous, dominantly physical, exothermic, and entropy decrement process that could be well described by the slip model and the dual‐site Langmuir model. Those thermodynamic parameters, including interface potential, exhibited a series of interesting tendencies with the changes in adsorption temperature and pressure. Under the conditions of 273 K and 100 kPa, the adsorption capacity and the interface potential were 4.6 mmol/g and −16.7 J/g, respectively. And the site energy ranged from 2.57 to 5.13 kJ/mol in the test conditions, which became narrow with increasing temperature. The temperature exhibited positive effects on interface potential, enthalpy change, entropy change, enthalpy change, internal energy change but negative effects on adsorption capacity, Gibbs free energy change, and Helmholtz free energy change. Interestingly, the pressure exhibited the opposite effect trends. The peak pressure with maximum temperature effect at a given temperature and the peak temperature with maximum pressure effect at a given pressure were found to exist for some thermodynamic parameters. These exhibited a different but significantly beneficial perspective to understand the mass and energy transfer during CO2 adsorption on the biochar at constant temperature and isopiestic pressure, which have rarely been reported before.

Experimental Study of Energy Evolution at a Discontinuity in Rock under Cyclic Loading and Unloading.

Energy is often dissipated and released in the process of rock deformation and failure. To study the energy evolution of rock discontinuities under cyclic loading and unloading, cement mortar was used as rock material and a CSS-1950 rock biaxial rheological testing machine was used to conduct graded cyclic loading and unloading tests on Barton’s standard profile line discontinuities with different joint roughness coefficients (JRCs). According to the deformation characteristics of the rock discontinuity sample, the change of internal energy is calculated and analyzed. The experimental results show that under the same cyclic stress, the samples harden with the increase in the number of cycles. With the increase of cyclic stress, the dissipated energy density of each stage gradually exceeds the elastic energy density and occupies a dominant position and increases rapidly as failure becomes imminent. In the process of increasing the shear stress step-by-step, the elastic energy ratio shows a downward trend, but the dissipated energy is contrary to it. The energy dissipation ratio can be used to characterize the internal damage of the sample under load. In the initial stage of fractional loading, the sample is in the extrusion compaction stage, and the energy dissipation ratio remains quasi-constant; then the fracture develops steadily, the damage inside the sample intensifies, and the energy dissipation ratio increases linearly (albeit at a low rate). When the energy storage limit is reached, the growth rate of energy dissipation ratio increases and changes when the stress level reaches a certain threshold. The increase of the roughness of rock discontinuity samples will improve their energy storage capacity to a certain extent.