Energy Function Research Articles

Isotope Effects on State-to-State Photodissociation Dynamics of D2S in Its First Absorption Band.

State-to-state photodissociation dynamics of D2S in its first absorption band were explored by utilizing recently developed diabatic potential energy surfaces (PESs). Quantum dynamics calculations, involving the first two strongly coupled 1A″ states, were executed employing a Chebyshev real wavepacket method. The nonadiabatic channel via the conical intersection (CI) is facile, direct, and fast, leading to the production of rotationally and vibrationally cold SD(X̃2Π). The calculated absorption spectrum, product state distributions, and angular distributions are in reasonable agreement with the experimental results, although some discrepancies exist at 193.3 nm. Compared with H2S, there are obvious isotope effects on rotational state distributions for D2S photodissociation in its first absorption band. Moreover, we scrutinize the variation of product state distributions as a function of photon energy and the vibrational mediated photodissociation of the parent molecule. Due to the diverse shapes of the three fundamental vibrational wave functions, photoexcited wavepackets access distinct segments of the upper-state PES, resulting in a disparate absorption spectrum and ro-vibrational distributions via the nonadiabatic transition. This study provides a comprehensive figure of the isotopic effect and wavelength dependence on the photofragmentation behaviors from D2S photodissociation, which should attract more experimental and theoretical attention to this prototypical system.

An adaptive energy regulation in a memristive map linearized from a circuit with two memristive channels

Nonlinear circuits can show multistability when a magnetic flux-dependent memristor (MFDM) or a charge-sensitive memristor (CSM) is incorporated into a one branch circuit, which helps estimate magnetic or electric field effects. In this paper, two different kinds of memristors are incorporated into two branch circuits composed of a capacitor and a nonlinear resistor, thus a memristive circuit with double memristive channels is designed. The circuit equations are presented, and the dynamics in this oscillator with two memristive terms are discussed. Then, the memristive oscillator is converted into a memristive map by applying linear transformation on the sampled time series for the memristive oscillator. The Hamilton energy function for the memristive oscillator is obtained by using the Helmholtz theorem, and it can be mapped from the field energy of the memristive circuit. An energy function for the dual memristive map is suggested by imposing suitable weights on the discrete energy function. The dynamical behaviors of the new memristive map are investigated, and an adaptive law is proposed to regulate the firing mode in the memristive map. This work will provide a theoretical basis and experimental guidance for oscillator-to-map transformation and discrete map energy calculation.

Kresling origami mechanics explained: Experiments and theory

From a kinematics perspective, a Kresling origami cell couples axial displacement (contraction/expansion) with twist, leading to non-rigid origami behavior. From an energy landscape perspective, the selection of the Kresling origami geometry, together with its fabrication process and material, lead to energy envelopes allowing single or multiple stable states. In this context, this paper explores the Kresling origami mechanics through mathematical modeling integrated with experimental testing. On the theoretical mechanics front, we present a comprehensive model incorporating the representative geometrical parameters of the Kresling origami cell into the corresponding energy function in order to capture its essential mechanical behavior. On the experimental mechanics front, we create two fixtures that demonstrate the ability to control axial displacement (contraction/expansion) and twist independently, without imposing any constraints on the chiral arrangement of individual cells within the Kresling origami array (composed of multiple cells). Finally, we show the coexistence of multiple mechanical and morphological configurations within the same Kresling array by programming its loading modes, i.e., compression or twist. The fundamental nature of this work makes it applicable to several field of engineering, including soft robotics and mechanical computing.

An optimized denoised bias correction model with local pre-fitting function for weak boundary image segmentation

The active contour model (ACM) plays a paramount part in grasping visual properties of images and exacting targets of interest. It is overwhelming hardship for traditional ACMs to segment images with noise, intensity inhomogeneity or low contrast and consider computation speed for practical applicability. Therefore, an optimized denoised bias correction (ODBC) model incorporating the pre-piecewise fitting function and the variational denoised term into the energy function is proposed for images with low contrast and intensity inhomogeneity. An optimized gradient descent equation and an upgraded regularization term are produced to enhance the robustness and sensitivity of this model. Experiments are conducted to validate that ODBC model possesses the superiority of reliability and speed in segmenting images with inhomogeneous intensity and strengthens the robustness to initial contours. The results manifest that mIOU of ODBC model exceeds 0.9, superior to prime ACMs and deep learning schemes, in segmenting images associated and unrelated with the dataset.

Imaging faults and fractures with the difference of fast and slow shear-wave splitting reflectivity, Δγ(S): 3D/9C survey in Midland Basin, West Texas, and 3D/3C survey in Washakie Basin, Wyoming

One of the most important applications of shear-wave (S-wave) seismic exploration has been in reservoir fracture characterization. While many advancements have been made over the past 30 years to compute and correct for the long-wavelength kinematics of S-wave splitting (SWS) (fast S-wave polarization directions and slow S-wave time delays), practically no progress has been made in imaging the short-wavelength reflectivity of fractures directly with Δγ(S). This property is the contrast in the SWS anisotropy parameter, γ(S), and represents the reflection amplitude at vertical incidence for changes in fracture density and orientation across an interface. In this article, we examine the Lupin nine-component survey in Midland Basin, Texas, for the technical reliability of imaging fractures in depth with converted P to S waves (PS waves) guided by pure-mode horizontal shear waves and vertical shear waves. Final Δγ(S) amplitude maps for each mode show sensitivity to fractures, faults, and the maximum horizontal stress direction. These maps are computed from the difference between fast and slow S-wave stacks (after SWS analysis and correction) and P-wave amplitude variation with offset gradient stacks. The S-wave difference maps identify an east–west lineament, possibly a strike-slip fault or fracture corridor, that is not observed by P-wave depth slices. Pure-mode S waves and PS waves are orders of magnitude more sensitive to Δγ(S) than P waves. We also review the development of Δγ(S) and find that it has been relatively unexploited by the exploration industry. In addition, we demonstrate that Δγ(S) can be obtained directly from the objective function of the transverse energy to correct for SWS, and show a four-component Alford rotation example from a previous PS-wave survey in the Washakie Basin, Wyoming.

Lifespan prediction procedure of volume nanogratings imprinted by femtosecond laser in optical glasses

Volume nanogratings imprinted by infrared femtosecond laser in oxide glasses exhibit a characteristic birefringent signature, which translates into measurable retardance. Upon thermal annealing, such signature is progressively erased, typical of nanograting erasure. In this work, we propose a procedure to predict the lifespan of nanogratings by two main approaches: 1/ numerical modeling of optical retardance ageing using the Rayleigh-Plesset equation, and 2/exploiting VAREPA (VAriable REaction PAthways) framework fed by simulated ageing data. By considering experimental time – temperature annealing conditions, the modeled retardance is gathered as a function of demarcation energy to build a so-called Master Curve and then compared to accelerated ageing experiments. The erasure constant rate k0 can be determined for 8 commercial optical glasses. Based on a distributed Rayleigh-Plesset model, k0 and activation energy distribution are linked to glass viscosity and its temperature dependency. Finally, we discussed the restrictions on VAREPA application for an accurate lifetime prediction. This work provides guidelines for the future development of nanogratings based devices and applications, including optical data storage, birefringent devices, and optical sensors, through a judicious choice of glass composition and associated properties.

Performance study of organic photovoltaic/thermal system with synergistic effect of photocatalytic and thermal catalytic technology

Organic photovoltaic cells are considered to be an effective solution for maintaining excellent electrical energy output in high temperature environment. However, the application of OPV alone has a low utilization rate of the solar spectrum. The combined application of OPV and other technologies is explored to improve the utilization efficiency of the solar spectrum. Based on the above gaps, this study proposes an organic photovoltaic/thermal system with synergistic effect of photocatalytic and thermal catalytic (PC/TC-OPV/T). By integrating organic photovoltaic cells, photocatalytic technology, thermal catalysis technology and photothermal components, the utilization efficiency of the solar spectrum is improved, and the triple functions of formaldehyde removal, electrical energy and hot water are realized. Therefore, this study proposes a new air purification-thermal-electrical model, establishes the heat transfer balance equation inside the system and the air purification and mass transfer balance equation in the air duct, proposes the performance evaluation index of the system, and uses Ansys Fluent software to predict the working characteristics of the system under different operating conditions, and draw the following conclusions: (1) Under the synergistic action of photocatalytic and thermal catalytic technologies, the formaldehyde removal efficiency is 84.4%, which is 30% higher than that of photocatalytic alone. (2) The electrical efficiency of the new system benefits from high solar irradiance and environment temperature, enabling it to achieve the efficiency of 17.84% within the research scope. (3) Under the research conditions, the instantaneous water flow heating efficiency of the system is up to 69.6%.

Micro-macro analysis of Hyperelastic auxetic lattice structures under finite-strain regime

This paper addresses the intricate analysis of lattice structures, pivotal components in engineering applications, confronted by challenges arising from their diverse unit cells (UCs) and complex behavior across micromechanical and macro-scale dimensions. The present study deals with a comprehensive analysis of lattice structure with honeycomb and re-entrant auxetic unit cells under large deformation via both a robust finite element analysis (FEA) and experimental tests. The proposed FEA is developed based on the hyperelastic Mooney–Rivlin strain energy function and the novel exact motion field that can fully describe the projection of cross-section. The results demonstrate that mechanical parameters such as Young's modulus, Poisson's ratio, and shear modulus have significant nonlinear behaviors with respect to UC geometrical parameters that are crucial for optimization across varied operational conditions. Additionally, the lattices made of TPU material and fabricated by Fused Deposition Modeling are tested under three-point bending and compression considering contact interaction. The results reveal highly nonlinear responses due to instabilities in some links and material nonlinearity. Furthermore, the behavior of lattice structures is exceedingly dependent on the orientations and types of UCs. It also can be found that both of the proposed FEA and constitutive model are in good agreement with experimental data.

Large deviation principle of multiplicative Ising models on Markov–Cayley trees

In this paper, we study the large deviation principle (LDP) for two types (Type I and Type II) of multiplicative Ising models. For Types I and II, the explicit formulas for the free energy functions and the associated rate functions are derived. Furthermore, we prove that those free energy functions are differentiable, which indicates that both systems are characterized by a lack of phase transition phenomena.

Distributed Learning Control for High-Speed Trains Subject to Operation Safety Constraints.

Trajectory tracking problems related to high-speed trains (HSTs) are fundamental issues that affect the operation safety and ride comfort. This study proposes a distributed learning control scheme based on a multiagent system framework for trajectory tracking of HSTs subject to operation safety constraints. Two different connection modes are considered between the carriages: 1) a soft connection achieved via information exchange and 2) a hard connection enforced via couplers. Both relative displacement and speed constraints are carefully analyzed in the tracking control process. By constructing an appropriate barrier composite energy function, the convergence of the tracking error and satisfaction of the operation safety constraints are rigorously proven for the proposed scheme. The theoretical results are verified using numerical simulations.

Equivalent converter method for analyzing complex DC–DC converting systems

AbstractThis paper introduces a new approach for analyzing the dynamics of DC–DC converters. Currently, the primary widely accepted method for examining dynamic processes is the Small Signal Analysis technique. However, when applied to modern complex converters, this method poses additional challenges in formulating and solving systems of differential equations. The method proposed in this paper is based on its application to the analysis of dynamic modes of energy functions—Lagrangians. These functions make it possible to define simple criteria to describe the course of dynamic processes, and in the end define an equivalent (approximating) conventional converter identical to the original one with respect to the course of dynamics. If the magnetic and electrical energies in the Lagrangians of both the converters are equal, the outcome is practically identical transient processes. These findings were confirmed by both theoretical analysis and experimentally modelling the dynamics of the initial converter and an equivalent to it in the Matlab–Simscape program. An additional possibility of using the transfer functions of a conventional boost converter for the theoretical analysis of the converters of much greater orders is also discussed. The authors’ experiments confirm the correctness of their theoretical conclusions.

Preserving non-negative porosity values in a bi-phase elasto-plastic material under Terzaghi’s effective stress principle

Poromechanics is a well-established field of continuum mechanics which seeks to model materials with multiple phases, usually a stiff solid phase and fluid phases of liquids or gases. Applications are widespread particularly in geomechanics where Terzaghi’s effective stress is widely used to solve engineering soil mechanics problems. This approach assumes that the solid phase is incompressible, an assumption that leads to many advantages and simplifications without major loss of fidelity to the real world. Under the assumption of finite (as opposed to infinitesimal) strains, the poromechanics of two- or bi-phase materials gains complexity and while the compressible solid phase case has received attention from researchers, the incompressible case has received less. For the finite strain - incompressible solid phase case there is a fundamental issue with standard material models, in that for some loadings solid skeleton mass conservation is violated and negative Eulerian porosities are predicted. While, to the authors’ best knowledge, acknowledgement of this essential problem has been disregarded in the literature, an elegant solution is presented here, where the constraint on Eulerian porosity can be incorporated into the free energy function for a material. The formulation is explained in detail, soundly grounded in the laws of thermodynamics and validated on a number of illustrative examples.

Quantification in high-energy resolution Auger electron spectroscopy; Proposal of a reference target convolution technique for direct spectra

Currently, high-energy resolution Auger electron spectroscopy (AES) is utilized for chemical-state qualitative analysis, such as x-ray photoelectron spectroscopy. It is highly desirable to perform quantitative analysis using the high-energy resolution direct spectra used for qualitative analysis. However, AES analysis parameters, such as relative sensitivity factors (RSFs), derived from conventional-energy resolution differentiated spectra cannot be adopted for high-energy resolution direct spectra. Furthermore, for quantification by high-energy resolution direct spectra, there is no established method for determining peak intensity, and no database of RSFs is available in surface analysis communities. Therefore, we tasked ourselves with investigating the use of the analysis parameters obtained from conventional-energy resolution-differentiated spectra obtained with a cylindrical mirror analyzer (CMA)-type AES instrument for high-energy resolution direct spectra measured with a spherical capacitor analyzer (SCA)-type AES instrument. The convolution technique proposed here is achieved by using a conventional-energy resolution spectral dataset obtained with CMA-AES as a target. By applying the convolution with the window function of the convoluted function of the Gaussian function and rectangular function, high-energy resolution direct spectra containing the inherent nature of fine structures are converted to the similar shapes of conventional-energy resolution direct spectra after the Shirley type background subtraction [Watanabe et al., J. Vac. Sci. Technol. A 41, 043209 (2023)]. Results revealed that for all spectra of conventional-energy resolution spectra taken with CMA-AES, as well as high-energy resolution spectra taken with SCA-AES with various energy resolutions, the ratios of the background-subtracted direct peak areas and the differentiated peak-to-peak intensities were well-aligned along the identical parabolic curve as a function of the kinetic energy (KE). Experimental results also revealed that the generalized conversion function f(KE;ΔE)=IareacmaIareaconv.sca(KE;ΔE), which is the ratio of the conventional-energy resolution spectral area (Iareacma) and the convoluted high-energy resolution spectral area (Iareaconv.sca), which can transform differentiated intensities of convoluted high-energy resolution spectra, such that they are similar to those of conventional-energy resolution spectra obtained using the CMA-AES instrument, being a function of KE and the energy resolution ΔE. By applying the conversion function, the historically accumulated AES analysis parameters for conventional-energy resolution differentiated spectra can be adopted to differentiated high-energy resolution spectra. Finally, the results revealed the sufficiency of the conversion function obtained by the actual measurements of the four reference specimens for the practical quantification of high-energy resolution AES direct spectra.

Review on Design and Development of Four Directional Fire Protection System

Abstract: The Development of an autonomous Four-directional fire-fighting robot has long been approaching. The creation of such equipment makes it possible to rescue people and property more quickly with less fire damage. As professionals, it is our responsibility to design and evaluate fire extinguishers and extinguishers. For this project we created a solar powered feature for uninterruptible power supply. Wireless controlled mobile robot. The robot can move around the building model, locate the fire, and then extinguish it using water spray. The development of autonomous firefighting robots is a long-standing need. Thanks to the development of this equipment, people and goods can be rescued quickly, with little fire damage. As experts, our job is to design and test fire detection and suppression systems. In this project, we developed a solar energy function for non-interruptive energy products. Wireless mobile robots. The robot can move within the building model, find the fire and extinguish it with the help of water spray

Energetically stable curve fitting to hyperelastic models based on uniaxial and biaxial tensile tests

Hyperelastic constitutive laws in biomechanics are used to model soft tissues, and material model parameters are often determined by performing curve fitting on data from uniaxial or biaxial tensile tests. The strain energy function of the applied constitutive law must to be energetically stable; however, this condition is not inherently provided by most currently available models. This study provides a procedure to determine stable strain energy functions in a biaxial strain space based on either uniaxial or biaxial tensile tests. Instead of conservative, strain-independent conditions, a stability region is defined in the strain space based on the sample’s tensile tests, thus allowing optimisation within a wider parameter space, resulting in better approximations. An extension of the Levenberg–Marquardt algorithm incorporating user-defined stability constraints is proposed, and the constrained optimisation algorithm is applied to isotropic and anisotropic models. The uniqueness of solutions of the Fung model is also discussed. The material model parameters of stable solutions for soft tissue measurements from various literature sources are determined to demonstrate the proposed procedure. Applying appropriate constraints in the optimisation algorithm resulted in stable and physically permissible constrained solutions for the strain energy function, in contrast to the results of most unconstrained optimisation cases.

Matrix projective synchronization and mechanical analysis of unified chaotic system

This article explores the mechanical analysis of a unified chaotic system and matrix projective synchronization (MPS). The sufficient conditions to achieve MPS of unified chaotic system have derived. The mechanics of unified chaotic system have been examined in contrast with Kolmogorov system, Euler equation, and Hamiltonian function. The Casimir energy function is also introduced to analyze the system dynamics. The unified chaotic system has been transformed into Kolmogorov type system and decomposed into four types of torques: inertial, internal, dissipation, and external torque. In order to view the mechanics behind the unified chaotic system, different particular cases have been discussed. Five scenarios are examined using combinations of various torques in order to identify the key elements in chaos creation and their physical significance. The bifurcation diagram, Lyapunov exponent and Lyapunov dimension validates the generation of chaos for different particular cases.

Supervisory control of quantitative Petri nets for fixed‐initial‐credit energy problems using a game structure

AbstractThis work investigates quantitative supervisory control of discrete event systems modeled with Petri nets under the fixed‐initial‐credit energy objective. A weight function referred to as an energy function is defined on a Petri net to characterize the energy level of a transition. The proposed fixed‐initial‐credit energy problem aims to design a supervisor such that the energy level of a transition sequence in a supervised system is higher than 0 under a given initial energy level. The problem is eventually transformed into a two‐player game between a system and a supervisor; supervisor synthesis is reduced to finding a winning strategy in the two‐player game. Instead of enumerating the complete state space of the underlying Petri net, two information structures are utilized, namely the conventional basis reachability graph and the newly proposed essential marking graph, to construct two‐player games based on each of them. It is shown that a winning strategy for a supervisor decoded from the game based on the basis reachability graph of the Petri net is a solution to the problem but is in general restrictive. Further, it is shown that the set of strategies for a supervisor in the game based on the essential marking graph is consistent with that from the game based on the reachability graph of a Petri net. The two developed approaches do not require an exhaustive exploration of the state space of a plant, thus achieving higher efficiency.

Photoionization of Nitrile-substituted Naphthalene and Benzene: Cation Spectroscopy, Photostability, and Implications for Photoelectric Gas Heating

We investigate the vacuum ultraviolet (VUV) photodynamics of gas phase 1- and 2-cyanonaphthalene and cyanobenzene, recently detected in the Taurus molecular cloud, by combining synchrotron radiation and a double imaging electron/ion coincidence setup. The high-resolution threshold photoelectron spectra (TPES) of all three molecules are obtained experimentally from which the adiabatic ionization energies are reported with very high accuracy, particularly for 2-cyanonaphthalene, for which no data exist at this level of precision. Theoretical calculations are performed to compare with the TPES for the ground electronic state of the cations. Furthermore, the different features observed in the extended TPES have been assigned to the different molecular orbitals with the help of the outer valence Green's function calculations. The present experiments also shed light on the kinetic energy distribution of the photoelectrons as a function of the incident photon energy, to describe their contribution to the photoelectric heating effect in the interstellar medium. In this context, we show how kinetic energy distributions can be obtained from our data for any given photon energy, such as the omnipresent Lyα line, or any given interstellar radiation field (ISRF). In addition, from the total ion yields, we estimate the photorates for a few ISRFs. Finally, we discuss the photodissociation of the two cyanonaphthalenes, quoting the activation energies of the dissociation channels with the help of Rice–Ramsperger–Kassel–Marcus modeling. It is observed that CN substitution does not cause any appreciable change to the VUV dissociative photoionization relaxation channel.

First‐Principles Calculations to Investigate the Ground State, Mechanical Stability, Electronic Structure, and Optical Properties of Tl2SnX3 (X = S, Se, Te)

AbstractIn this work, the Density Functional Theory (DFT) analysis of the Tl2SnX3 series (X = S, Se, Te) is performed, and the ground states are confirmed by the calculation of the elastic constant Cij. Based on the DFT calculation, the Tl2SnX3 structures are direct‐gap semiconductors with bandgaps of 1.434, 1.181, and 0.907 eV, respectively. Chalcogen substitution significantly impacts their electronic structures, notably increasing the Density of States (DOS) width in the valence band from sulfur to tellurium, and shifting the dielectric function's real part, ε1(ω), toward lower energies. This change means that the optical activity and response to electric fields are better, with Tl2SnTe3 showing the best polarization response and light‐matter interaction abilities. Optical tests show that Tl2SnTe3 has very high optical absorption, peaking at ≈17 × 104 cm−1 along [010], and reflectivity levels above 90%, marking its suitability for high‐reflectivity applications. Moreover, loss energy function analysis also shows that Tl2SnTe3 has a strong electron loss resonance at lower energies, which means it has strong interactions with electrons.

Schrödinger-Maxwell equations driven by mixed local-nonlocal operators

In this paper we prove existence of solutions to Schrödinger-Maxwell type systems involving mixed local-nonlocal operators. Two different models are considered: classical Schrödinger-Maxwell equations and Schrödinger-Maxwell equations with a coercive potential, and the main novelty is that the nonlocal part of the operator is allowed to be nonpositive definite according to a real parameter. We then provide a range of parameter values to ensure the existence of solitary standing waves, obtained as Mountain Pass critical points for the associated energy functionals.