Total Internal Energy Research Articles

The study of design and optimisation for CFRP combined pier anti-collision device

A CFRP honeycomb combination anti-collision device with a larger anti-collision level, greater crashworthiness, and longer service life was designed to safeguard the ship and piers in the event of an unintentional collision. Taking large-tonnage cargo ships and common bridge piers in the middle reaches of the Yangtze River as the research objects, the energy conversion response, impact force response and impact depth response of the collision were studied considering the collision conditions between the ship and the bare pier and the collision avoidance device. On this basis, the response surface method, variance analysis method and efficacy coefficient method were further used to take the shell thickness of the collision avoidance device and the thickness of the internal steel structure as the design parameters. The multi-objective optimisation design of the CFRP composite anti-collision device is carried out by selecting the ship impact force, the total internal energy absorbed by the anti-collision device, the total mass, and the inner diameter of the honeycomb steel structure as the optimisation objectives. The results show that the impact force reduction rate reaches 82.7%, the overall mass is greatly reduced, the maximum deformation is within a reasonable range, and the collision resistance is optimised.

Study of the Spectroscopic Analysis, Electronic Structure and Thermodynamic Properties of Ethyl benzene Using First-Principles Density Functional Theory

This study describes the optimized molecular structure, spectroscopic analysis, electronic structure and thermodynamics properties of the ethylbenzene molecule using first-principles DFT/B3LYP method with 6-311++G(d,p) basis set. The C-H in-plane bending vibration is observed between 1400 and 1050 cm-1, while the C-H out-of-plane bending vibration is observed between 1000 and 675 cm-1. The benzene ring has the most negative potential that corresponds to the attraction of proton due to concentrated electron density while the moderate positive potential is localized closed to the hydrogen atom. Analysis of the HOMO and LUMO in ethylbenzene anticipates an energy disparity of 6.3028 eV, a value closely matching the energy gap derived from DOS calculations. Mulliken charge analysis of the ethylbenzene molecules gives the information that all the hydrogen atom corresponds to the positive charges while all the carbon atom except C3 corresponds to the negative charge and the values of the global parameters such as hardness, chemical potential, electronegativity, electrophilicity index, softness are found to be 3.1514 eV, -3.5979 eV, 3.5979 eV, 2.0538 eV and 0.3173 eV-1 respectively. Various thermodynamic parameters such as heat capacity at constant volume, heat capacity at constant pressure, total internal energy, enthalpy and entropy, exhibit a rising trend with increasing temperature whereas Gibbs free energy shows an inverse relationship with temperature variation.

Influence of Leg Geometry on the Performance of Bi2Te3 Thermoelectric Generators

This study utilized COMSOL Multiphysics to simulate the performance of a thermoelectric module (TEM) made by alumina (Al2O3), copper (Cu), and bismuth telluride (Bi2Te3) materials, specifically exploring different leg geometries. The TEM design had Al2O3 for insulation, Cu for conducting, and Bi2Te3 for TE legs between the Cu layers. Investigated the influence of square and rectangular TE legs with heights of 2.0 mm, 2.75 mm, and 3.5 mm on critical parameters, including temperature gradient, electric potential, normalized current density, and total internal energy within the TEM. Furthermore, the impact of varying thicknesses in the insulator and conductor layers of the TEM was explored. The results consistently demonstrated that the square leg geometry, particularly when configured with a height of 2.75 mm, outperformed other leg geometries. Consequently, it is recommend the adoption of square-shaped Bi2Te3 TEM, measuring 1 mm × 1 mm × 2.75 mm, with a 0.50 mm Al2O3 thickness and 0.125 mm Cu thickness during the manufacturing process. Study how factors like the Seebeck coefficient (S), thermal conductivity (k), and electrical conductivity (σ) affect temperature differences in the leg design of TE devices. At lower temperatures, modeling reveals lower electrical conductivity and enhanced thermal conductivity, highlighting the significance of S = ± 2.37×10⁻⁴ V/K. This illustrates the high potential of TEM for applications in thermoelectric generator (TEG) manufacturing.

Mechanistic evaluation of contrasting modulation in conformation and catalytic performance of urease by surface interaction of graphene oxide and amine- functionalized graphene oxide nanosheets

The increasing use of graphene-based nanomaterials raises concerns about their potential environmental impact as ecotoxicants. This article examines the interaction and effects of graphene oxide (GO) and its amine-derived (GONH2) 2-D nanosheets on urease dynamics, a crucial enzyme in soil nutrient cycling, through spectroscopic, microscopic, and computational analyses. The findings reveal the distinct interaction mechanisms: GO formed ground - and excited-state complexes with urease; thus, fluorescence quenching was static and dynamic via hydrophobic interaction. In contrast, GONH2 nanosheets formed a ground-state complex by static quenching involving Van der Waals and hydrogen bonding. These interactions were energetically favored and altered tryptophan (Trp) residues’ microenvironment more than tyrosine (Tyr). The average exciton lifetime of urease in the presence of GO have decreased from 4.34 ns to 3.647 ns at the mere concentration of 7.11 µM, while for GONH2, no discernable change (4.16 ns) was observed even at the concentration of 16.75 µM. Primarily, the strong interaction of GO leads to the rearrangement of polypeptide structure, reduced α-helices to 12 %, and increased β-sheets by six times. In contrast, with GONH2, α-helices were reduced to 79 %, and β-sheets were increased by 1.8 times at the similar concentration. Molecular docking revealed that neither GO nor GONH2 interacted with the active site of urease, and binding was primarily via hydrophobic, Van der Waals, and hydrogen bonding, concurrent with in-vitro incubation results. Positive total energy (3.85 kJ mol−1) during molecular docking analysis of urease-GO interaction and inhibition in enzyme activity to 62 %, altered Vmax value (0.04606 ± 0.001 mM/s), without affecting the Km (4.78045 ± 0.12 mM) suggested that inhibition was noncompetitive and steric clashes due to disruptive binding might drove the inhibition. Meanwhile, negative total internal energy (-3.97 kJ mol−1) during urease + GONH2 binding and enhanced enzymatic activity by 32 % in-vitro without altering Vmax (0.063091 ± 0.003 mM/s) and Km (4.953943 ± 0.2 mM) values suggested that urease's binding site was well-complemented by GONH2 nanosheets, serving as a redox-mediator and radical-quencher.

Staged Z-pinch radiation-hydrodynamic simulations on a 20-MA driver

We report on one-dimensional simulations of a staged Z-pinch (SZP) fusion scheme using the radiation-hydrodynamics code HYDRA [Marinak et al., Phys. Plasmas 8, 2275 (2001)]. A pulsed-power driver, based on the Z-machine at Sandia National Laboratories, with a peak current around 20 MA, is used to implode a high-Z gas liner surrounding a cylindrical DT fuel target. For the best conditions used in this work, excluding some physical processes, such as mix, we find a “clean” fusion yield of 7.05 MJ (2.5 ×1018 neutrons), thus showing the potential for high yields using this scheme. The design achieving this yield was determined through a study of different liner materials, liner masses, and fuel masses. We also address previous simulations of the SZP setup that used ad hoc limits of the total internal energy of the liner that can artificially increase fusion yields.

Experimental and numerical investigation of steel–concrete composite beam subjected to contact explosion

The steel–concrete composite beam, consisting of a concrete slab, a steel beam, and shear connectors, is extensively utilized in bridge engineering due to its effective utilization of material properties and convenient construction. Considering the significant impact of explosive incidents on bridge safety, and the limited experimental research on blast performance of composite beams, this study tested three small-scale SC composite beams arranged with commonly used shear connectors, including studs, PBL ribs, and combination connectors, under contact explosion with 200 g of TNT. Finite element (FE) models, validated by the experimental data, were established to conduct damage analysis to understand the damage mode and characteristics of SC composite beams. The results showed that the SC composite beams exhibit a localized damage pattern concentrated in the mid-span of the beams under contact explosions. The concrete spalling on the bottom surfaces could be divided into two parts by the top flange of the steel beam. The concrete slab, which absorbs more than 94 % of the total internal energy of the SC composite beams, plays the most important role in reducing the damage to the beams under contact explosion. In some aspects, the type of shear connectors influences the crack pattern, concrete spalling degree, the deformation of the steel beam, and the difference in acceleration response between the concrete slab and steel beam, but on the whole, it has a limited effect on the damage mode and degree of SC composite beams subjected to contact explosion.

All SNAP25 molecules in the vesicle-plasma membrane contact zone change conformation during vesicle priming.

In neuronal cell types, vesicular exocytosis is governed by the SNARE (soluble NSF attachment receptor) complex consisting of synaptobrevin2, SNAP25, and syntaxin1. These proteins are required for vesicle priming and fusion. We generated an improved SNAP25-based SNARE COmplex Reporter (SCORE2) incorporating mCeruelan3 and Venus and overexpressed it in SNAP25 knockout embryonic mouse chromaffin cells. This construct rescues vesicle fusion with properties indistinguishable from fusion in wild-type cells. Combining electrochemical imaging of individual release events using electrochemical detector arrays with total internal reflection fluorescence resonance energy transfer (TIR-FRET) imaging reveals a rapid FRET increase preceding individual fusion events by 65 ms. The experiments are performed under conditions of a steady-state cycle of docking, priming, and fusion, and the delay suggests that the FRET change reflects tight docking and priming of the vesicle, followed by fusion after ~65 ms. Given the absence of wt SNAP25, SCORE2 allows determination of the number of molecules at fusion sites and the number that changes conformation. The number of SNAP25 molecules changing conformation in the priming step increases with vesicle size and SNAP25 density in the plasma membrane and equals the number of copies present in the vesicle-plasma membrane contact zone. We estimate that in wt cells, 6 to 7 copies of SNAP25 change conformation during the priming step.

Multi-Sensor Observations Reveal Large-Amplitude Nonlinear Internal Waves in the Kara Gates, Arctic Ocean

We present multi-sensor measurements from satellites, unmanned aerial vehicle, marine radar, thermal profilers, and repeated conductivity–temperature–depth casts made in the Kara Gates strait connecting the Barents and the Kara Seas during spring tide in August 2021. Analysis of the field data during an 18-h period from four stations provides evidence that a complex sill in the Kara Gates is the site of regular production of intense large-amplitude nonlinear internal waves. Satellite data show a presence of a relatively warm northeastward surface current from the Barents Sea toward the Kara Sea attaining 0.8–0.9 m/s. Triangle-shaped measurements using three thermal profilers revealed pronounced vertical thermocline oscillations up to 40 m associated with propagation of short-period nonlinear internal waves of depression generated by stratified flow passing a system of shallow sills in the strait. The most intense waves were recorded during the ebb tide slackening and reversal when the background flow was predominantly supercritical. Observed internal waves had wavelengths of ~100 m and traveled northeastward with phase speeds of 0.8–0.9 m/s. The total internal wave energy per unit crest length for the largest waves was estimated to be equal to 1.0–1.8 MJ/m.

Nonlinear Internal Tides in a Realistically Forced Global Ocean Simulation

AbstractThe decay of the low‐mode internal tide due to the superharmonic energy cascade is investigated in a realistically forced global Hybrid Coordinate Ocean Model simulation with 1/25° (4 km) horizontal grid spacing. Time‐mean and depth‐integrated supertidal kinetic energy is found to be largest near low‐latitude internal tide generation sites, such as the Bay of Bengal, Amazon Shelf, and Mascarene Ridge. The supertidal kinetic energy can make up to 50% of the total internal tide kinetic energy several hundred kilometers from the generation sites. As opposed to the tidal flux divergence, the supertidal flux divergence does not correlate with the barotropic to baroclinic energy conversion. Instead, the time‐mean and depth‐integrated supertidal flux divergence correlates with the nonlinear kinetic energy transfers from (sub)tidal to supertidal frequency bands as estimated with a novel coarse‐graining approach. The regular spaced banding patterns of the surface‐intensified nonlinear energy transfers are attributed to semidiurnal mode 1 and mode 2 internal waves that interfere constructively at the surface. This causes patches where both surface tidal kinetic energy and nonlinear energy transfers are elevated. The simulated internal tide off the Amazon Shelf steepens significantly near these patches, generating solitary‐like waves in good agreement with Synthetic Aperture Radar imagery. Globally, we find that regions of high supertidal energy flux also show a high correlation with observed instances of internal solitary waves.

Fundamental Relation for the Ideal Gas in the Gravitational Field and Heat Flow.

We formulate the first law of global thermodynamics for stationary states of the ideal gas in the gravitational field subjected to heat flow. We map the non-uniform system (described by profiles of the density and temperature) onto the uniform one and show that the total internal energy U(S*,V,N,L,M*) is the function of the following parameters of state: the non-equilibrium entropy S*, volume V, number of particles, N, height of the column L along the gravitational force, and renormalized mass of a particle M*. Each parameter corresponds to a different way of energy exchange with the environment. The parameter M* changes internal energy due to the shift of the centre of mass induced by the heat flux. We give analytical expressions for the non-equilibrium entropy S* and effective mass M*. When the heat flow goes to zero, S* approaches equilibrium entropy. Additionally, when the gravitational field vanishes, our fundamental relation reduces to the fundamental relation at equilibrium.

On thermodynamic extremal principles in gradient plasticity with energetic forces

Incremental energy minimization is revisited as a method of determining an incremental solution for rate-independent dissipative solids undergoing isothermal quasi-static deformation. The incremental minimization is applied to the total internal energy of the compound thermodynamic system that consists of a deforming body with internal variables, a conservative loading device, and an ambient heat reservoir. It is shown that the difference between the virtual and actual dissipation rates plays a fundamental role in this minimization, which is related to thermodynamic extremal principles of local and global type. The analysis is carried out within the gradient plasticity framework with the energetic forces derived as the variational derivative of the Helmholtz free energy depending on the spatial gradient of arbitrary internal variables. Specifications are given for existing models of gradient plasticity.

FE model to define impacting resistance behavior of RC beams protected by AlSi10Mg buffer interlayer

Inspired by the biological structure of the beetle elytra, the bio-inspired honeycomb column thin-walled structure (BHTS) is designed as lightweight buffer interlayer to prevent the key parts of reinforced concrete (RC) beams of engineering structures under overload impact from destruction. The mechanical properties of the additive manufacturing technology selective laser melting (AM-SLM) BHTS material AlSi10Mg were determined through quasi-static and medium-speed uniaxial compression tests. Based on the drop weight test models, the maximum impact force and duration, maximum displacement and residual displacement, energy proportion and other indicators, the impact of the buffer interlayer on the dynamic response of RC beams were compared under the drop weight test at different heights. The results showed that the proposed BHTS buffer interlayer has a very significant impact protection effect on the RC beam: the average energy absorption (EA) of the BHTS buffer interlayer is 25.65 % of the total internal energy, which greatly reduces the energy input into the RC beam. In addition, based on the study of the drop weight test simulation of BHTS buffer interlayer, an approximate calculation model for predicting the ultimate displacement of BHTS-RC beam is proposed, which can be used as an important method for assessing the damaging degree of reinforced beam under impact load quickly. BHTS can be used as a replaceable structure to avoid impact damage to RC components in structural engineering.

On thermodynamics of compact objects

With the recent progress in observations of astrophysical black holes, it has become more important to understand in detail the physics of strongly gravitating horizonless objects. If the objects identified in the observations are indeed horizonless and ultracompact, high curvature effects may become important, and their explorations may be intimately related to new physics beyond General Relativity (GR). In this paper, we revisit the concept of statistical thermodynamics in curved spacetime, focusing on self-gravitating compact systems without event horizons. In the literature, gravitational field equations are in general assumed a priori in the thermodynamic treatment, which may lead to difficulties for theories of modified gravity, given the more complicated structure of field equations. Here, we consider thermodynamic behavior of the matter source, instead of the physical mass, hence avoiding the explicit input of field equations in the derivation of thermodynamic laws. We show that the conventional first law of thermodynamics is retrieved once the thermodynamic volume, which is in general different from the geometric volume, is appropriately identified. For demonstrations of our approach, we consider familiar examples of self-gravitating gas in GR, where the connection to previous studies becomes clear. We also discuss 2-2-holes in quadratic gravity, a novel example of black hole mimickers that features super-Planckian curvatures in the interior. These objects exhibit universal high curvature effects in thermodynamics, which happen to be conveniently encoded in the thermodynamic volume. Interesting connections to black hole thermodynamics also emerge when the physical mass is treated as the total internal energy.

Evaluation of Computational Analysis for Stiffened Slab Using Finite Strip Method

A rectangular slab stiffened by ribs oriented perpendicular to the support of the slab as structurally equivalent to an orthotropic plate has been analyzed using the finite strip method. The analytic formulation was obtained from the governing equation of motion of the plate using the classical plate theory to an arbitrary boundary and initial condition. The stiffness formulation from total internal energy was considered. The force-displacement equation technique by applying stiffness and uniformly distributed loading was used to obtain the modal solution and hence, displacement at an arbitrary point of the plate for the assumed harmonic function. Approximate stresses following the displacement are also obtained. The comparative solution of the equilibrium differential equation is obtained by means of convergent series expansions of levy plates and the application of Timoshenko and Woinowsky-Krieger averaging of bending rigidity, utilizing suitable orthogonal displacement functions. A computer procedure based on the finite strip method is given through the application of numerical examples, which shows that the procedure provides good results, especially with low discretization and computational effort.

Unruh effect and Takagi's statistics inversion in strained graphene

We present a theoretical study of how a spatially varying quasiparticle velocity in honeycomb lattices, achievable using strained graphene or in engineered cold-atom optical lattices that have a spatial dependence to the local tunneling amplitude, can yield the Rindler Hamiltonian embodying an observer accelerating in Minkowski space-time. Within this setup, a sudden switch on of the spatially varying tunneling (or strain) yields a spontaneous production of electron-hole pairs, an analog version of the Unruh effect characterized by the Unruh temperature. We discuss how this thermal behavior, along with Takagi's statistics inversion, can manifest themselves in photoemission and scanning tunneling microscopy experiments. We also calculate the average electronic conductivity and find that it grows linearly with frequency $\ensuremath{\omega}$. Finally, we find that the total system energy at zero environment temperature looks like Planck's blackbody result for photons due to the aforementioned statistics inversion, whereas for an initial thermally excited state of fermions, the total internal energy undergoes stimulated particle reduction.

Arthur E. Haas, from the Atom to the Cosmos—Struggles for a Scientific Career in the Early 20th Century

Arthur E. Haas, from the Atom to the Cosmos—Struggles for a Scientific Career in the Early 20th Century

Crashworthiness Study of a Newly Developed Civil Aircraft Fuselage Section with Auxiliary Fuel Tank Reinforced with Composite Foam

Over the past two decades, aircraft crashworthiness has seen major developments, mainly with modern computing systems and commercial finite element (FE) codes. The structure and the material have been designed to absorb more kinetic energy to ensure enough safety during a controlled crash condition. However, the fuselage section with an onboard auxiliary fuel tank requires special arrangements, since the inclined strut system with an efficient energy absorber is difficult to install under the cabin floor due to the space occupied by the fuel tank. To solve this shortcoming, a PVC composite foam along with an aluminum plate is introduced beneath the fuel tank to improve the crashworthiness metrics of the fuselage. Drop tests for both the conventional design and the proposed model are investigated by adopting the nonlinear explicit dynamics code Ansys Autodyn, with an impact velocity of 9.14 m/s. It was found that the kinetic energy absorption of the original fuselage section can be improved by 3.54% by reinforcing the foam and the plate. Moreover, they contribute to 20% of total internal energy dissipation. Numerical outcomes also suggest that the cabin floor surface experiences a 41% lower maximum stress, in addition to the mitigation of the maximum peak acceleration responses of the cabin floor at different measured locations from 6% to 36%.

The number of SNAP25 molecules changing conformation preceding a fusion event increases with vesicle size.

Regulated vesicular exocytosis is governed by the SNARE complex, consisting of synaptobrevin2, SNAP25 and syntaxin. However, the number of copies of SNARE complexes that are cooperating in membrane fusion is highly debated. To estimate the number of SNARE complexes changing conformation preceding a single fusion event we used a SNAP25-based SNARE Complex Reporter (SCORE2) incorporating mCeruelan-3 and Venus and overexpressed it in SNAP25 knockout embryonic mouse chromaffin cells. We demonstrated that all parameters of exocytosis in SNAP25 knockout cells are completely rescued by SCORE2 (SNARE Complex REporter2) and unchanged compared to wild type cells. Combining electrochemical imaging of individual release events using electrochemical detector arrays with total internal reflection fluorescence resonance energy transfer (TIR-FRET) imaging of SCORE2 conformational changes we detected a rapid FRET increase specifically associated with individual fusion events. This conformational change precedes fusion by ∼60 ms. Calibrated by the SCORE2 overexpression factor, we estimate that in wt cells ∼7 copies of SNAP25 change conformation preceding a fusion event. This number increased by ∼20% in L-Dopa-loaded vesicles which exhibited 1.67 fold larger quantal size and presumably 21% larger diameter. The number of SNAP25 copies undergoing a conformational change increases with vesicle size in parallel to the estimated area of the vesicle-plasma membrane contact zone. The results suggest that the FRET change of SCORE2 reports the docking of the vesicle, which is associated with a conformational of all SNAP25 copies in the contact zone.

Thermodynamic Properties and Critical Behavior of Spin-Polarized Atomic Hydrogen (H↓) Using the Quantum Second-Virial Coefficient

The quantum–mechanical formulations for the second-virial, and the acoustic virial, coefficients are derived for spin-polarized atomic hydrogen (H↓). The dependence of these coefficients on the temperature T as well as the nuclear polarization $$\zeta \;$$ is analyzed. This is done for the first time. The main inputs in these computations are the scattering phase shifts, which are obtained using the Lippmann–Schwinger equation, with the Silvera triplet-state potential. Starting with these phase shifts, comprehensive calculations of the thermophysical properties for this system are performed for T ranging from 1 µK to 100 K, and $$\zeta \;$$ varying from 0 to 1. These properties include, in addition to the quantum second-virial coefficient and the acoustic virial coefficient: the pressure–polarization–temperature $$\left( {P {-} \zeta {-} T} \right)$$ behavior, the entropy (per atom), the speed of sound, the second-virial correction (to the total internal energy per atom and unit density), and the specific heat capacity (per atom and unit density). The Boyle temperature and the Joule inversion temperature are determined. The T-dependence of these thermophysical properties, and related quantities, is explored. As expected, this dependence is most evident in the low-T limit, where quantum effects predominate. The corresponding $$\zeta$$ -dependence becomes noticeable at 80 K and below. It is observed that the virial coefficients tend to decrease with increasing $$\zeta$$ . Comparison of the present results to previous results are included whenever possible. The overall agreement is very good. As T is lowered, the disruptive effects of thermal energy are weakened relative to the attractive interactions between the atoms. Consequently, the H↓ gas makes a transition to a state of higher order and lower entropy—Bose–Einstein condensation (BEC). This is explored carefully.

The minus sign in the first law of de Sitter horizons

Due to a well-known, but curious, minus sign in the Gibbons-Hawking first law for the static patch of de Sitter space, the entropy of the cosmological horizon is reduced by the addition of Killing energy. This minus sign raises the puzzling question how the thermodynamics of the static patch should be understood. We argue the confusion arises because of a mistaken interpretation of the matter Killing energy as the total internal energy, and resolve the puzzle by introducing a system boundary at which a proper thermodynamic ensemble can be specified. When this boundary shrinks to zero size the total internal energy of the ensemble (the Brown-York energy) vanishes, as does its variation. Part of this vanishing variation is thermalized, captured by the horizon entropy variation, and part is the matter contribution, which may or may not be thermalized. If the matter is in global equilibrium at the de Sitter temperature, the first law becomes the statement that the generalized entropy is stationary.