Structural Properties Of System Research Articles

A Port-Hamiltonian Approach to Modeling and Control of an Electro-Thermal Microgrid

Abstract We address the problems of modeling and controlling multi-energy microgrids (meMGs) composed of an electrical and a thermal system, which are connected via heat pumps (HPs). At first, we model the individual subsystems in a port-Hamiltonian (pH) framework. Then, by exploiting the structural properties of pH systems, we interconnect the subsystems in a passive manner and show that the overall meMG is shifted passive with respect to the control input-output mapping. We then use this property to propose a distributed passivity based-control (PBC) that addresses frequency and temperature regulation by utilizing the resources in the meMG in a proportional fashion and renders the closed-loop equilibrium asymptotically stable.

Effect of synthesis route on the structural and electrical properties of sodium bismuth titanate: A comparative study of solid-state and polyol mediated synthesis

Sodium bismuth titanate (NBT) was synthesized through two different synthesis methods: solid-state reaction (SS) and polyol mediated synthesis (PM). The effect of synthesis route on the structural and electrical properties of NBT system has been investigated. Polyol mediated synthesize NBT sample result in single-phase at relatively lower temperature than of prepared via the solid-state reaction method. The Rietveld refinement of the XRD data confirms that both the sample crystallizes in the rhombohedral perovskite phase with R3c space group. The morphological properties indicate that the grain size of the polyol method processed sample is smaller and slightly agglomerated than the one prepared via solid-state route. Impedance results reveal enhanced bulk conductivity for PM synthesized samples as compared to SS route. Thus, the polyol mediated synthesis may be a better approach for the synthesis of NBT samples. Furthermore, a correlation between the structural and electrical properties for both methods synthesized samples have been discussed to explain the conductivity behaviour.

Jahn-Teller and Pseudo-Jahn-Teller Effects: From Particular Features to General Tools in Exploring Molecular and Solid State Properties.

In a generalization of the latest achievements in this field, and as a pattern of massive applications, we present here the Jahn-Teller effect (JTE) and pseudo-JTE (PJTE) as general tools in the study of physical and chemical phenomena related to structural properties of polyatomic systems. We show that the JTE and PJTE are no more specific features of particular (rare) systems (as it was assumed earlier), but virtual properties of all molecular and solid state formations. They occur as a result of vibronic coupling that compensates for the error (inadequacy) introduced in semi-classical definitions of polyatomic configurations by their high-symmetry nuclear positions, thus appending the basic understanding of related phenomena with a new dimension. The implications of the JTE and PJTE in observable properties varies significantly, being especially strong in the states of electronic degeneracy or pseudodegeneracy, but they cannot be a priory fully excluded for any system. After the introductory sections we demonstrate some of the more recent results of the influence of these effects on the observables in physical and chemical phenomena, together with a wide range of applications. The latter are conventionally separated in three parts: intermediate states in chemical and photochemical reactions, manipulation of structural properties of polyatomic systems targeting the JTE and PJTE, and applications in materials science. The illustrative examples include the origin of sudden polarization in photochemical reactions, methods of planarization of puckered (buckled) two-dimensional systems, modification of crystal sublattices by targeting the JTE parameters, the defining role of JTE and PJTE in electronics and spintronics, the origin of ferroelectricity and multiferroicity, as well as a novel property of solids, orientational polarization, and its applications.

Advancement of food-derived mixed protein systems: Interactions, aggregations, and functional properties.

Recently, interests in binary protein systems have been developed considerably ascribed to the sustainability, environment-friendly, rich in nutrition, low cost, and tunable mechanical properties of these systems. However, the molecular coalition is challenged by the complex mechanisms of interaction, aggregation, gelation, and emulsifying of the mixed system in which another protein is introduced. To overcome these fundamental difficulties and better modulate the structural and functional properties of binary systems, efforts have been steered to gain basic information regarding the underlying dynamics, theories, and physicochemical characteristics of mixed systems. Therefore, the present review provides an overview of the current studies on the behaviors of proteins in such systems and highlights shortcomings and future challenges when applied in scientific fields.

Algebraic analysis of the structural properties of parametric linear time‐invariant systems

By using techniques borrowed from algebraic geometry, some tests are proposed to certify structural properties (such as reachability, observability, controllability, constructibility, stabilisability, and detectability) of discrete-time and continuous-time linear time-invariant systems. These results are then generalised for linear time-invariant systems depending polynomially on some real parameters, by exploiting the notion of Gröbner cover. The main innovation of the proposed results with respect to existing techniques is that they provide exact certificates for the structural properties of linear time-invariant systems. Examples of application are given all throughout the study to illustrate and validate the theoretical results.

The effect of extruded breadfruit flour on structural and physicochemical properties of beef emulsion modeling systems

The objective was to determine structural and physicochemical properties of beef emulsion modeling systems prepared with native breadfruit flour and four different extruded breadfruit flours. Extrusion conditions for the flours were summarized as two different specific mechanical energies (74 or 145 kJ/kg) and four unique melt temperatures (83 °C, 100 °C, 105 °C, or 126 °C). Meat emulsions formulated at 3% replacement of beef with native or extruded breadfruit flours were compared with control (no additional flour) formulations. Replacement of beef with breadfruit flour (either native or extruded) did not significantly change cooking loss or instrumental redness values of cooked meat emulsions. Interestingly, replacement of beef with the fully gelatinized extruded breadfruit flours altered viscosity during heating as indicated by lower values for storage modulus (44.75% to 62.53% decrease compared with control) and lower values for loss modulus (25.90% to 52.54% decrease compared with control). This resulted in meat emulsions with a significant reduction in textural hardness (28.78% to 37.62% decrease compared with control).

A review on nonlinear DNA physics.

The study and the investigation of structural and dynamical properties of complex systems have attracted considerable interest among scientists in general and physicists and biologists in particular. The present review paper represents a broad overview of the research performed over the nonlinear dynamics of DNA, devoted to some different aspects of DNA physics and including analytical, quantum and computational tools to understand nonlinear DNA physics. We review in detail the semi-discrete approximation within helicoidal Peyrard–Bishop model and show that localized modulated solitary waves, usually called breathers, can emerge and move along the DNA. Since living processes occur at submolecular level, we then discuss a quantum treatment to address the problem of how charge and energy are transported on DNA and how they may play an important role for the functioning of living cells. While this problem has attracted the attention of researchers for a long time, it is still poorly understood how charge and energy transport can occur at distances comparable to the size of macromolecules. Here, we review a theory based on the mechanism of ‘self-trapping’ of electrons due to their interaction with mechanical (thermal) oscillation of the DNA structure. We also describe recent computational models that have been developed to capture nonlinear mechanics of DNA in vitro and in vivo, possibly under topological constraints. Finally, we provide some conjectures on potential future directions for this field.

Methods to prevent silken powder collapsing and clushing during storage

The article is devoted to the current problem of increasing the nutritional value and safety of flour confectionery products. The possibility of using white mulberry powder as a sugar substitute in the formulation of this type of product has been revealed. The analysis of the chemical composition of the powder has been carried out. It has been found to be prone to caking and clumping, making it difficult to dose. The expediency of using additives with a high content of dietary fiber (cellulose) as anti-caking agents has been substantiated. Particular attention is paid to the plant fibers "Sanacel Wheat 90" and "Vitazel", wheat bran and germ product. On the example of two-phase free-flowing systems, the possibility of controlling the structural and mechanical properties of dispersed systems has been proved. The ratio of the ingredients of the mixture was established, proposals for their use in the production of flour confectionery were developed.

Non-covalent supramolecular systems with photoinduced electron transfer based on zinc bis(dipyrromethenate)s and C60

In this paper, we continue the study of non-covalent supramolecular systems based on zinc bis(dipyrromethenate)s ([Zn2L2]) with fullerene C60 and present the results of study of [Zn2L2]s periphery methylation degree effect on their supramolecular complexation with C60. The structural organization and spectral properties of supramolecular systems based on [Zn2L2]s and C60 were studied by means of UV/vis, fluorescence, time-resolved fluorescence, elemental analysis, FT-IR, PXRD, 1H NMR, DOSY spectroscopy, and computer modeling. The revealed features and the photoelectrochemical characteristics (photocurrent density, IPCE) obtained by the amperometric method give evidence of potential usage of [Zn2L2]s-C60 supramolecular complexes with 1:4 stoichiometry as optoelectronics and photovoltaic devices components.

First principle study of electronic structural and physical properties of CaO[sbnd]SiO2[sbnd]Al2O3 ternary slag system by using Ab Initio molecular and lattice dynamics

In current first principle studies the electronic, structural and physical properties of CaOSiO2Al2O3 ternary slag system were calculated by ab initio molecular dynamics (AIMD) and ab initio lattice dynamics (AILD) simulations, based on density functional theory (DFT). The density of states (DOS) and electrons density difference (EDD) were evaluated to understand the bonding nature of slag network structure. Furthermore, the atomic and bond population analysis shows that the SiO bonds are stronger as compared to AlO and CaO bonds in molten slag. The radial distribution function (RDF) and mean square displacement (MSD) were obtained at 1773 K, which are used to calculate the diffusion coefficient and viscosity of ternary slag system. Moreover, the temperature dependence of diffusion coefficient and viscosity were investigated in the range of 1350–2100 K. The calculated results indicate that the diffusion coefficient decreases and viscosity increases at high temperature for CSA slag system.

Molecular Dynamics Simulation of the Structures, Dynamics, and Aggregation of Dissolved Organic Matter.

Dissolved organic matter (DOM) plays a significant role in the transport and transformation of pollutants in the aquatic environment. However, the experimental characterization of DOM has been limited mainly to bulk properties, and the molecular-level interactions among various components of DOM remain to be fully characterized. Here, we use molecular dynamics (MD) simulations to probe the structural properties of model DOM systems at atomic detail. The 200 ns simulations, validated by available experimental data, reveal processes and mechanisms by which chemical species (cations, peptides, lipids, lignin, carbohydrates, and some low-molecular-weight aliphatic and aromatic compounds) aggregate to form complex DOM. The DOM aggregates are dynamic, consisting of a hydrophobic core and amphiphilic exterior. The lipid tails and other hydrophobic fragments form the core, with hydrophilic and amphiphilic groups exposed to water, making DOM accessible to both polar and nonpolar species. Thus, the lipid component acts as a nucleator, whereas cations (especially Ca2+) connect the molecular fragments on the surface by coordinating with the O-containing functional groups of DOM. The structural details revealed here provide new insights including surface accessible atoms, overall assemblage, and interactions among the molecules of DOM for understanding the kinetics and mechanisms through which DOM interacts with metal and other contaminants.

Machine learning approaches for structural and thermodynamic properties of a Lennard-Jones fluid.

Predicting the functional properties of many molecular systems relies on understanding how atomistic interactions give rise to macroscale observables. However, current attempts to develop predictive models for the structural and thermodynamic properties of condensed-phase systems often rely on extensive parameter fitting to empirically selected functional forms whose effectiveness is limited to a narrow range of physical conditions. In this article, we illustrate how these traditional fitting paradigms can be superseded using machine learning. Specifically, we use the results of molecular dynamics simulations to train machine learning protocols that are able to produce the radial distribution function, pressure, and internal energy of a Lennard-Jones fluid with increased accuracy in comparison to previous theoretical methods. The radial distribution function is determined using a variant of the segmented linear regression with the multivariate function decomposition approach developed by Craven et al. [J. Phys. Chem. Lett. 11, 4372 (2020)]. The pressure and internal energy are determined using expressions containing the learned radial distribution function and also a kernel ridge regression process that is trained directly on thermodynamic properties measured in simulation. The presented results suggest that the structural and thermodynamic properties of fluids may be determined more accurately through machine learning than through human-guided functional forms.

Structural properties of PbTe quantum dots revealed by high-energy x-ray diffraction

High-energy x-ray diffraction (HE-XRD) experiments combined with an analysis based on atomic-pair-distribution functions can be an effective tool for probing low-dimensional materials. Here, we show how such an analysis can be used to gain insight into structural properties of PbTe nanoparticles (NPs). We interpret our HE-XRD data using an orthorhombic Pnma phase of PbTe, which is an orthorhombic distortion of the rocksalt phase. Although local crystal geometry can vary substantially with particle size at scales below 10 nm, and for very small NPs the particle size itself influences x-ray diffraction patterns, our study shows that HE-XRD can provide a unique nano-characterization tool for unraveling structural properties of nanoscale systems.

Hamiltonian and alias-free hybrid particle-field molecular dynamics.

Hybrid particle-field molecular dynamics combines standard molecular potentials with density-field models into a computationally efficient methodology that is well-adapted for the study of mesoscale soft matter systems. Here, we introduce a new formulation based on filtered densities and a particle-mesh formalism that allows for Hamiltonian dynamics and alias-free force computation. This is achieved by introducing a length scale for the particle-field interactions independent of the numerical grid used to represent the density fields, enabling systematic convergence of the forces upon grid refinement. Our scheme generalizes the original particle-field molecular dynamics implementations presented in the literature, finding them as limit conditions. The accuracy of this new formulation is benchmarked by considering simple monoatomic systems described by the standard hybrid particle-field potentials. We find that by controlling the time step and grid size, conservation of energy and momenta, as well as disappearance of alias, is obtained. Increasing the particle-field interaction length scale permits the use of larger time steps and coarser grids. This promotes the use of multiple time step strategies over the quasi-instantaneous approximation, which is found to not conserve energy and momenta equally well. Finally, our investigations of the structural and dynamic properties of simple monoatomic systems show a consistent behavior between the present formulation and Gaussian core models.

Facilitation in reaction systems

Reaction systems is a formal model of computation which originated as a model of interactions between biochemical reactions in the living cell. These interactions are based on two mechanisms, facilitation and inhibition, and this is well reflected in the formulation of reaction systems. In this paper, we investigate the facilitation aspect of reaction systems, where the products of a reaction may facilitate other reactions by providing some of their reactants. This aspect is formalized through positive dependency graphs which depict explicitly such facilitating interactions. The focus of the paper is on demonstrating how structural properties of reaction systems defined through the properties of their positive dependency graphs influence the behavioural properties of (suitable subclasses of) reaction systems, which, as usual, are defined through their transition graphs.

Analyzing the structural properties of bike-sharing networks: Evidence from the United States, Canada, and China

Abstract To solve the last-mile problem and promote low carbon transportation, hundreds of cities around the world have launched bike-sharing services. A growing number of studies have been mining bike-sharing data from different cities to understand bike-sharing systems. However, there is still a lack of comprehensive understanding of a bike-sharing network structure. Thus, this paper attempts to use complex network theory and spatial autocorrelation analysis approaches to examine structural properties of bike-sharing systems, quantify the importance of bike stations in the network, and evaluate their spatial clustering patterns. This research analyzes bike-sharing trip data from five different sized bike-sharing systems in the United States, Canada, and China. The results of network analysis reveal that the bike-sharing networks have a small-world property with a small average path length and a high clustering coefficient. Compared with medium-scale networks, the connectivity and accessibility of bike stations are relatively low in the large-scale bike-sharing network. Also, the connectivity of bike stations is positively related to their accessibility while they are not highly correlated with their intermediateness. The spatial clustering analysis results indicate that the spatial distributions of connectivity and accessibility of bike stations have a strong global spatial autocorrelation. Also, the stations with high connectivity and accessibility are concentrated in the urban centers, and the stations with low connectivity and accessibility are clustered in the periphery of the urban areas. However, their intermediateness does not show a strong global spatial clustering pattern, which implies that bike-sharing networks consist of multiple sub-groups. The findings provide new insights for transport planners and managers to understand bike-sharing systems and to improve their service quality.

Structural and dielectric properties of Cu-doped α-ZnMoO4 ceramic system for enhanced green light emission and potential microwave applications

In this article, the synthesis of the Zn1-xCuxMoO4 ceramic system was carried out by a solid-state reaction route, and their structural, morphological, and optical properties were investigated. The samples were characterized by X-ray diffraction, scanning electron microscopy, Raman spectroscopy, FT-IR spectroscopy, and UV–Vis spectrophotometry. Structural analysis confirms the formation of a triclinic structure with space group P $$\stackrel{-}{1}$$ and point group symmetry C1 without any secondary phase formation. The decrease in effective nuclear charge with the introduction of Cu2+ ion decreases the bandgap from 3.57 to 2.78 eV. The potential application in the visible (green) region of the electromagnetic spectrum is supported by the reduction of the bandgap. The increasing Cu2+ concentration is accompanied by Photoluminescence peaks being shifted toward larger wavelength side, covering a broad range of visible region from 300 to 600 nm. The broad range luminescence emission spectra that happened with ZnMoO4 occurred due to the electronic transition between (MoO4)2− complexes or between Mo4d and O2p states. Hakki–Coleman method was applied for the study of microwave dielectric parameters and shows increase of eobs from 8.35 to 12.52 with a simultaneous decrease in dielectric loss (tan δ) from 0.01 to 0.005, respectively. The corresponding quality factor (Q $$\times$$ f) was calculated. The observed high-quality factor could be used as high signal speed microwave materials.

Atomic uranium modified graphdiyne as catalytic material for hydrogen evolution reaction: An interfacial descriptor led mechanistic study

Catalysis operated on supported single metal atom is considered as one of the vital efforts for chemical and energy conversion. Despite the enormous amount of research on single transition metal (TM) enhanced graphdiyne (GDY) material, its modification with slightly depleted uranium remains unexplored. Herein, we conducted relativistic density functional theory (DFT) calculations for the accumulation of atomic uranium inside size-suitable GDY pore. The stability of graphdiyne-uranium (GDY-U) is corroborated in terms of short U–C bond distances (2.34–2.44 Å), with local depletion of charge and greater U(5f)-C(p) molecular orbital overlap. The magnificent structural and electronic properties of GDY-U system qualify it for the investigation of hydrogen evolution reaction (HER). The HER performance of all exposed sites, including central metal atom and four dissimilarly coordinated acetylenic carbons has been examined and compared with that of pure GDY. As the overall HER interfacial descriptor, free energy change of the intermediate state (ΔGH∗) at the central metal surface of GDY-U was found to be most favorable (0.153 eV) amongst all sites and far superior to those of pure GDY. In addition to the uranium surface, the coordinated carbons also show improved HER activity, indicating the enhancement of the system upon metal insertion. The calculated ΔGH∗ of the GDY-U system here is comparable to some of the recently reported GDY-TM materials, suggesting that atomic uranium could be an exceptional alternative for applied common catalysts.

Structural, Vibrational, and Electronic Properties of Trigonal Cu2SrSnS4 Photovoltaic Absorber from First-Principles Calculations

In the search for sustainable alternate absorber materials for photovoltaic applications, the family of chalcogenides provide a promising solution. While the most commonly studied Cu2ZnSnS4 based kesterite solar cells seem to have intrinsic drawbacks such as low-efficiency arising from defects and anti-disorder in the Cu-Zn sites, substituting other elements in the Cu/Zn sites have been considered. In this direction, Cu2(Ba,Sr)SnS4 provide an interesting alternative as they possibly help limit the intrinsic anti-site disorder in the system which is of primary concern with regard to efficiency loses. In this study, we report the structural, vibrational, and electronic properties of trigonal structured Cu2SrSnS4 quarternary system computed from first-principles density functional theory paving way for further characterization and analysis within this class of materials.

Structural, Chemical, and Local Properties of Layered Metal Chalcophosphate Systems

Structural, Chemical, and Local Properties of Layered Metal Chalcophosphate Systems