State Diagram Research Articles

Elasto-inertial instability in torsional flows of shear-thinning viscoelastic fluids

It is well known that inertia-free shearing flows of a viscoelastic fluid with curved streamlines, such as the torsional flow between a rotating cone and plate or the flow in a Taylor–Couette geometry, can become unstable to a three-dimensional time-dependent instability at conditions exceeding a critical Weissenberg ( $Wi$ ) number. However, the combined effects of fluid elasticity, shear thinning and finite inertia (as quantified by the Reynolds number $Re$ ) on the onset of elasto-inertial instabilities are not fully understood. Using a set of cone–plate geometries, we experimentally explore the entire $Wi$ – $Re$ phase space for a series of nonlinear viscoelastic fluids (with the dependence on shear rate $\dot{\gamma}$ quantified using a shear-thinning parameter $\beta _P(\dot {\gamma })$ ). We tune $\beta _P(\dot {\gamma })$ by varying the dissolved polymer concentration in solution. This progressively reduces shear thinning but leads to finite inertial effects before the onset of elastic instability, and thus naturally results in elasto-inertial coupling. Time-resolved rheometric measurements and flow visualization experiments allow us to investigate the effects of flow geometry, and document the combined effects of varying $Wi, Re$ and $\beta _P(\dot {\gamma })$ on the emergence of secondary motions at the onset of instability. The resulting critical state diagram quantitatively depicts the competition between the stabilizing effects of shear thinning and the destabilizing effects of inertia. We extend the curved streamline instability criterion of Pakdel & McKinley (Phys. Rev. Lett., vol. 77, no. 12, 1996, p. 2459) for the onset of purely elastic instability in curvilinear geometries by using scaling arguments to incorporate shear thinning and finite inertial effects. The augmented condition facilitates predictions of the onset of instability over a broader range of flow conditions, and thus bridges the gap between purely elastic and elasto-inertial curved streamline instabilities.

Magnetism and electronic properties of ConMoP (n = 1 ~ 5) cluster: a DFT study.

Hydrogen has emerged as a promising clean energy carrier, underscoring the imperative need to comprehend its adsorption mechanisms. This study delves into the magnetic and electronic properties of Co-Mo-P clusters, aiming to unveil their catalytic potential in hydrogen production. Employing density functional theory (DFT), we optimized cluster configurations and scrutinized their magnetic behaviors. Our investigation unveiled 16 stable configurations of the ConMoP (n = 1 ~ 5) cluster, predominantly in steric forms. The magnetic attributes were primarily ascribed to the d orbitals of Co metal atoms, with Co3MoP exhibiting exceptional magnetic characteristics. Analysis of density of state diagrams revealed the prevalence of spin-up α-electrons in d orbitals, while spin-down β-electrons attenuated overall magnetic properties. Localized orbital (LOL) analysis highlighted stable covalent bonds within the clusters, affirming their catalytic potential. Orbital delocalization index (ODI) analysis revealed diverse spatial distribution ranges for orbitals across different configurations, suggesting a progressive attenuation of off-domain properties with increasing cluster size. Furthermore, infrared spectroscopy unveiled distinct vibrational peaks in various configurations, indicative of unique infrared activities. These findings contribute to a nuanced theoretical understanding of Co-Mo-P clusters and pave the path for future research aimed at augmenting their catalytic efficiency in hydrogen production. This study underscores the viability of Co-Mo-P clusters as alternatives to conventional Pt catalysts, offering insights into the design of novel materials for sustainable energy applications. Further research is warranted to explore the behavior of the Co-Mo-P system under diverse reaction conditions, fostering advancements in materials and energy science. In this study, we harnessed the ConMoP (n = 1 ~ 5) cluster as a simulation platform for probing the local structure of the material. Our aim was to scrutinize the magnetism, electronic characteristics influenced by the varying metal atoms within these clusters. A systematic exploration involved incrementing the number of metal atoms and expanding the cluster size to elucidate the corresponding property variations. Density functional theory (DFT) calculations were pivotal to our methodology, employing the B3LYP hybrid functional implemented in the Gaussian16 software package. The ConMoP (n = 1 ~ 5) cluster underwent optimization calculations and vibrational analysis at the def2-tzvp quantization level, yielding optimized configurations with diverse spin multiplet degrees. To comprehensively characterize and visually represent the stability, electronic features, and catalytic attributes of these configurations, we employed a suite of computational tools. Specifically, quantum chemistry software GaussView and wave function analysis software Multiwfn played integral roles. Through the integrated use of these computational tools, we acquired valuable insights into the magnetism, electronic characteristics of the ConMoP (n = 1 ~ 5) cluster, shedding light on their dependency on distinct metal atoms.

Two types of quaking and shear unjamming: State diagram for soft granular particles in quasistatic shear

Understanding intermittency, a ubiquitous behavior in flows of packed grains, is pivotal for establishing the rheology of granular matter. A straightforward explanation has been missing despite the long development of theories at various levels of abstraction. Here, we propose the use of a Stribeck-Hertz model that starts with the classic Coulomb friction but takes into account the interparticle , i.e., the reduction of friction coefficient with sliding speed as is commonly observed. Our numerical experiments reveal a state diagram that covers a wide range of packing fractions and show that incorporating the tribology enables the occurrence of quaking intermittency in the midrange of a dimensionless shear rate, consistent with prior experimental observations. Further study of the discontinuities in the evolution of the mean contact number leads to our discovery of two types of quaking that are distinguished by the abrupt or of neighboring contacts and reveal different pathways of microstructural change underlying these discrete events. In contrast to the prevailing paradigm in which shear is believed to promote jamming at intermediate densities, our study demonstrates that shear can also unjam a granular system, and this occurrence depends on the shear rate. Published by the American Physical Society 2024

State diagrams of green peas (Pisum sativum L.) powders with different maltodextrin additions.

The purpose of this study was to examine the effect of maltodextrin addition on the physical stability of powdered green peas. The evaluation of the physical state of the material was based on the equilibrium water content of the monolayer (Xm) and the glass transition temperatures of the powders at room temperature (Tg) and in the frozen state (Tg'). Graphical sorption characteristic at 25°C was determined using static-gravimetric method while capacity of the monolayer values was calculated from the mathematical GAB model. Differential scanning calorimetry was carried out in order to determine glass transition lines and freezing curves which combine together were used to plot state diagrams. Relationship between Tg and solid content were shown by using Gordon-Taylor model. Freezing data were modeled employing the Clausius-Clapeyron equation and its development-Chen model. Sorption isotherms showed sigmoidal shape characteristic for high-molecular weight materials. Monolayer moisture content varied between 0.047 and 0.106 g water/g solids. The glass transition temperature of anhydrous green peas increased in from 89.9 to 175.6°C while Tg' value changed from -43.4 to -26.6°C to as a result of 75% polysaccharide addition. The ultimate maximum-freeze-concentration conditions of the powders were observed in range from 0.783 to 0.814 g solids/g sample. Monolayer capacity, Tg and Tg' values increased with increasing maltodextrin amount in the sample which indicates that the addition of starch hydrolysate has a beneficial effect on the stability of powders stored frozen and at room temperature.

P–T–x State Diagram of the Co–Mg System

p–T–x State Diagram of the Co–Mg System

Construction of lignosulphonate-containing polymersomes and prospects for their use for elemental sulfur encapsulation

The renewable nature and natural origin of sulfite lignin (lignosulfonate) allow considering it as a potential raw material for the synthesis of valuable environmentally friendly polymer nanomaterials. To create them, a deep understanding of the relationship between the structure of the lignosulfonate macromolecule and the nature of intramolecular and intermolecular interactions is necessary, which would make it possible to control self-assembly processes and obtain nanostructures of specified sizes and morphology. The work discusses the structure formation processes occurring in the lignosulfonate – water – acetone system during the spontaneous formation of polymer nanostructures and submicrostructures. The electrostatic effects of sulfo groups and counterions under conditions of changing the medium polarity and their contribution to self-associations of lignosulfonates have been established. A state diagram was plotted for the ternary lignosulfonate – water – acetone system under conditions of induced phase separation at T = 298 K and under atmospheric pressure. The size and ζ-potential of these nanostructures and submicrostructures of lignosulfonates were estimated depending on the composition of the medium of their formation. The morphology of the resulting nanostructures and submicrostructures of lignosulfonates has been established. The vesicular nature of the aggregates (polymersomes) was confirmed, their shape being close to ideal spheroids with one hole, ranging in size from 40 to 500 nm. A multi-stage mechanism for the formation of lignosulfonate nanoassociates and submicroassociates is proposed. The encapsulating ability of our polymersomes with respect to elemental sulfur from the instant of its inception until the loss of aggregative and sedimentation stability was assessed. Lignosulfonate polymersomes can be recommended as additives to prevent the occluding effect of sulfur melts during hydrometallurgical processing of sulfide ores.

Mathematical modeling of early processes of morphogenesis of epithelial tissues

Studying morphogenetic processes through traditional methods, such as observa-tion and experimentation, can be highly complex and laborious. Utilizing mathematical modeling methods makes it possible to analyze big data and uncover patterns that may be unnoticed when employing traditional approaches. In this study, a vertex mathemati-cal model of squamous epithelial tissue morphogenesis is proposed. The elementary unit of the system is the cell, which can dynamically change its shape and size. We in-troduce a new potential that accounts not only for the elasticity of cell perimeters and areas but also for the elasticity of their internal angles. Additionally, we introduce an inte-gral equation of chemical signaling, which allows for the consideration of chemo-mechanical cell-cell interactions. In addition to the above, the model incorporates im-portant processes of real epithelia, such as cell proliferation and intercalation. Based on the simulation results, a diagram of the system's principal states was constructed as a function of control parameters. A parameter range is identified within which the cellular system adopts the most energetically favorable and stable configurations. Furthermore, two processes occur in the early stages of morphogenesis, namely morula formation and blastula formation. This paper provides a detailed physical and mathematical description of these processes. The obtained results can be utilized in developing methods for influ-encing morphogenetic processes in medical applications.

Research on design requirements for passive residual heat removal system of lead cooled fast reactor via model-based system engineering

Traditional text-based system engineering, which has been used in the design and application of passive residual heat removal system (PRHRS) for lead-cooled fast reactors, is prone to several problems such as low development efficiency, long iteration cycles, and model ambiguity. This study aims to effectively address the above-mentioned problems by adopting a model-based system engineering (MBSE) method, which has been preliminarily applied to meet the design requirements of a PRHRS. The design process has been implemented based on the preliminary design of the system architecture and consists of three stages: top-level requirement analysis, functional requirements analysis, and design requirements synthesis. The results of the top-level requirements analysis and the corresponding use case diagram can determine the requirements, top-level use cases, and scenario flow of the system. During the functional requirements analysis, the sequence, activity, and state machine diagrams are used to develop the system function model and provide early confirmation. By comparing these sequence diagrams, the requirements for omissions and inconsistencies can be effectively checked. In the design requirements synthesis stage, the Analytic Hierarchy Process is used to conduct preliminary trade-off calculations on the system architecture, after which a white box model is established during the system architecture design. Through these two steps, the analysis and design of the system architecture are ultimately achieved. The resulting system architecture ensures the consistency of the design requirements. Ultimately, a functional hazard analysis was conducted for a specific incident to validate case requirements and further refine the system architecture. Future research can further reduce the design risk, improve the design efficiency, and provide a practical reference for the design and optimization of PRHRS in digital lead-cooled fast reactors.

Role of Shape in Particle-Lipid Membrane Interactions: From Surfing to Full Engulfment.

Understanding and manipulating the interactions between foreign bodies and cell membranes during endo- and phagocytosis is of paramount importance, not only for the fate of living cells but also for numerous biomedical applications. This study aims to elucidate the role of variables such as anisotropic particle shape, curvature, orientation, membrane tension, and adhesive strength in this essential process using a minimal experimental biomimetic system comprising giant unilamellar vesicles and rod-like particles with different curvatures and aspect ratios. We find that the particle wrapping process is dictated by the balance between the elastic free energy penalty and adhesion free energy gain, leading to two distinct engulfment pathways, tip-first and side-first, emphasizing the significance of the particle orientation in determining the pathway. Moreover, our experimental results are consistent with theoretical predictions in a state diagram, showcasing how to control the wrapping pathway from surfing to partial to complete wrapping by the interplay between membrane tension and adhesive strength. At moderate particle concentrations, we observed the formation of rod clusters, which exhibited cooperative and sequential wrapping. Our study contributes to a comprehensive understanding of the mechanistic intricacies of endocytosis by highlighting how the interplay between the anisotropic particle shape, curvature, orientation, membrane tension, and adhesive strength can influence the engulfment pathway.

Transition metals doped Zr2CF2 as promising sensor and adsorbent for NH3

The effective adsorption and treatment of toxic gases have attracted great attention amongst researchers, particularly the use of new two-dimensional materials for achieving the adsorption of toxic gases. We applied the density functional theory to investigate the stability, geometric structural, electrical, and magnetic properties of NH3 molecules adsorbed on pristine, F-vacancy defected, and transition-metals (V, Cr, Mn, Y, Nb, and Mo) doped Zr2CF2. The charge transfer and adsorption energy of the original substrate were low, indicating that the interaction between NH3 and Zr2CF2 was primarily physical adsorption. After introducing F-vacancy and TM-doping, the adsorption stability was enhanced, with the large charge transfer and high adsorption energies indicating that the adsorption of NH3 transitioned to chemisorption. Electronic density of state diagrams suggested that the enhanced interaction was mainly caused by the hybridization of the d orbitals of dopants and p orbitals of the adsorbed NH3 molecules. The adsorption energy of NH3 molecules on Y-doped Zr2CF2 was the highest at a value of −1.425eV, and the material was also explored as an adsorbent for NH3 gas. After adsorbing six NH3 molecules, the Y-doped substrate had an average adsorption energy of −1.350eV and still maintained a good thermal stability at a temperature of 300 K. These results can provide insights into the development of sensors and adsorbents based on MXenes.

Biaxial tensile-compressive deformation on the electronic structure and optical properties of doped with different concentrations F–MoTe2: A first-principles study

Under the framework of density functional theory based on the first principles, the plane wave pseudopotential method was used to investigate the effects of biaxial stretch-compression deformation on the electrical structure and optical characteristics of molybdenum telluride systems doped with various fluorine atom concentrations. Electrical structure, density of states, charge transfer, and optical characteristics were calculated and thoroughly investigated in the molybdenum ditelluride system. The results demonstrate that the band gap shrinks with increasing fluorine atom doping concentration of fluorine atoms, and n-type doping occurs for different doping concentrations of halogen fluorine atoms. The semiconductor-quasi-metal transition occurs in the MoTe2 system when the doping concentration reaches 16.67%. After that, the fluorine atoms with 4% doping concentration were deformed by stretching and compression, and the semiconductor started to transition to quasi-metal as the amount of stretching increased. The deformation of the system changed considerably when the stretching amount was 14%. Compression induces a direct-to-indirect bandgap transition, transforming semiconductors into metals. Significant changes in electronic energy band diagrams and density of states diagrams. In terms of optical qualities, the absorption spectra of the entire system are blue-shifted during stretching and compression. The reflectance spectra are red-shifted and then blue-shifted.

2D lattice animal formation in the irreversible aggregation of patchy particles

With the self-assembly of patchy colloids, we can engineer many complex structures. In the present work, we are modeling spherical particles with 2 diagonally opposite patches using the Kern-Frenkel potential coupled with isotropic square well potential having different interaction ranges. The isotropic square well potential formed reversible bonds while the patches were irreversibly bonded. A state diagram is calculated where we observed a range of structures from a 1D chain, 2D planar cluster, and 3D random clusters depending on the width of the patch. These structures are controlled by the number of bonds each patch can form for a given patch angle. The range of the patch width can be analytically calculated using geometric arguments to identify different types of clusters, which agree with our simulations. The aggregation process was diffusion-limited, forming clusters with fractal dimension 2 in the low volume fraction limit, otherwise known as flocculation region, and 2.5 in the high volume fraction limit or percolation region, irrespective of the type of clusters formed. In the flocculation limit of the DLCA aggregation model, we expect a fractal dimension of 1.8, contrary to that, we observed the formation of lattice animals having a fractal dimension of 2. The presence of lattice animals is confirmed using the scaling laws of size distribution and chemical length of the clusters formed in the flocculation limit.

Expansion Kinetics of Flexible Polymers upon Release from a Disk-Shaped Confinement.

A general theory is developed to explain the expansion kinetics of a polymer released from a confining cavity in a d-dimensional space. At beginning, the decompressed chain undergoes an explosive expansion while keeping the structure resembling a sphere. As the process continues, the chain transitions to a coil conformation, and the expansion significantly slows down. The kinetics are derived by applying Onsager's variational principle. Computer simulations are then conducted in a quasi-two-dimensional space to verify the theory. The average expansion of the chain size exhibits a distinctive sigmoidal variation on a logarithmic scale, characterized by two times and associated exponents that represent the fast and the slow dynamics, respectively. Through an analysis of the kinetic state diagrams, two important universal behaviors are discovered in the two expansion stages. The intersection of the expansion speed curves allows us to define the crossover point between the stages and study its properties. The scaling relations of the characteristic times and exponents are thoroughly investigated under different confining conditions, with the results strongly supporting the theory. Additional calculations conducted in a three-dimensional (3D) space demonstrate the robustness of the proposed theory in describing the kinetics of polymer expansion in both 2D and 3D spaces.

CosmiXs: cosmic messenger spectra for indirect dark matter searches

The energy spectra of particles produced from dark matter (DM) annihilation or decay are one of the fundamental ingredients to calculate the predicted fluxes of cosmic rays and radiation searched for in indirect DM detection. We revisit the calculation of the source spectra for annihilating and decaying DM using the Vincia shower algorithm in Pythia to include QED and QCD final state radiation and diagrams for the EW corrections with massive bosons, not present in the default Pythia shower model. We take into account the spin information of the particles during the entire EW shower and the off-shell contributions from massive gauge bosons. Furthermore, we perform a dedicated tuning of the Vincia and Pythia parameters to LEP data on the production of pions, photons, and hyperons at the Z resonance and discuss the underlying uncertainties. To enable the use of our results in DM studies, we provide the tabulated source spectra for the most relevant cosmic messenger particles, namely antiprotons, positrons, γ rays and the three neutrino flavors, for all the fermionic and bosonic channels and DM masses between 5 GeV and 100 TeV, on github.

A Method for Modeling and Testing Near-Real-Time System Scenarios

Unmanned platforms are becoming more and more widely used in both civilian and military applications. The flight safety of such aircraft is crucial. Therefore, it becomes necessary to formally model and rigorously test their software. Commencement of an unmanned air vehicle’s (UAV) operation requires it undergoing a certification process, which further heightens the quality requirements. The validation process of the designed system is presented on the example of verifying the correctness of the operational scenario involving the transfer of control over a UAV between two ground control stations (GCSs). The paper introduces the method of designing unmanned aerial vehicles and testing their functionality based on finite-state machines. The architecture description of the system encompasses the use cases view and logical view of the 1+5 architectural views model. The paper concentrates on system requirements and their transformation into unified modeling language (UML) state machine diagrams. The authors present a method of mapping requirements to functions related to flight safety and system dynamics models expressed as communicating extended finite-state machines (CEFSMs). Moreover, the paper shows the rules for testing the correctness of state machine models using methods based on determining flows in directed graphs. It should be emphasized that the paper considers the certification of UAV software components from the system safety viewpoint, which directly affects the airworthiness of the air platform.

Material state diagrams for informed decision-making during drying of contemporary rice cultivars

Improper drying of rice can cause significant kernel defects. A rice material state diagram consisting of glass transition temperature (T g) at various moisture content (MC) levels is a tool that helps predict the appropriate drying temperatures to employ. The present diagrams were however developed for old rice cultivars which may be inadequate for predicting the drying behavior of contemporary cultivars. The objective of this study was therefore to develop material state diagrams along with updated T g prediction models tailored to accommodate the contemporary rice cultivars presently grown. In the study, 23 rice cultivars were analyzed and revealed average T g values of approximately 39, 41, 43, 45, and 47 °C at MC levels of 20%, 18%, 16%, 14%, and 12%, respectively. The updated material state diagrams developed from the results incorporated a T g prediction model, indicating elevated T g values and an improved R 2 value of 0.72, when compared to prior research findings.

Impact of the polymer dispersity on the properties of curcumin/polyvinylpyrrolidone amorphous solid dispersions

Amorphous solid dispersions (ASD) are known to enhance the absorption of poorly water-soluble drugs. In this work we synthesise well-defined Polyvinylpyrrolidone (PVP) to establish the impact of dispersity and chain-end functionality on the physical properties of Curcumin (CUR)/PVP ASD. Thermodynamic characterisation of synthesised PVP emphasises a strong effect of the dispersity on the glass transition temperature (Tg), 50 °C higher for synthesised PVP than for commercial PVP K12 of same molar mass. This increase of Tg affects the thermodynamic properties of CUR/PVP ASD successfully formulated up to 70 wt% of CUR by milling or solvent evaporation. The evolution of both the Tg and CUR solubility values versus CUR content points out the development of fairly strong CUR-PVP interactions that strengthen the antiplasticising effect of PVP on the Tg of ASD. However, for ASD formulated with commercial PVP this effect is counterbalanced at low CUR content by a plasticising effect due to the shortest PVP chains. Moreover, the overlay of the phase and state diagrams highlights the strong impact of the polymer dispersity on the stability of CUR/PVP ASD. ASD formulated with low dispersity PVP are stable on larger temperature and concentration ranges than those formulated with PVP K12.

QCD phase diagram and equation of state in background electric fields

The phase diagram and the equation of state of quantum chromodynamics (QCD) is investigated in the presence of weak background electric fields by means of continuum extrapolated lattice simulations. The complex action problem at nonzero electric field is circumvented by a novel Taylor expansion, enabling the determination of the linear response of the thermal QCD medium to constant electric fields—in contrast to simulations at imaginary electric fields, which, as we demonstrate, involve an infrared singularity. Besides the electric susceptibility of QCD matter, we determine the dependence of the Polyakov loop on the field strength to leading order. Our results indicate a plasma-type behavior with a negative susceptibility at all temperatures, as well as an increase in the transition temperature as the electric field grows. Published by the American Physical Society 2024

Does training improve users' mental models about adaptive cruise control?

While Advanced Driver Assistance Systems (ADAS) promise safety benefits to drivers, there is evidence to suggest that drivers are unaware or uninformed about their vehicles’ systems and thus have poor mental models about the systems. Previous studies suggest that training improves drivers’ mental models, although some studies report limited impacts. This study investigated the relationship between training and drivers’ mental models about Adaptive Cruise Control (ACC), compared the impact of two different training approaches on drivers’ mental models, and examined the relationship between driver knowledge and trust regarding ADAS technologies. This study was conducted online, and participants were randomly and equally assigned to one of three training groups – owner’s manual (text-based); state diagram visualization; or sham (control). Surveys measured their trust and mental models about ACC before and after training. The results found that the text-based group outperformed the visualization group and the control group in terms of post-training overall mental model scores, but these differences were not statistically significant. No correlation between post-training mental model scores and overall trust scores was found. This study provides evidence that training improves users’ mental models about technology and finds that different training platforms or paradigms may affect learning differently.

Effects of the maximum flow ramping rates on the long-term operation decisions of a hydropower plant

This paper presents a study on the influence of maximum ramping rates (MRR) on the annual operation of a real hydropower plant. For this purpose, an annual optimization model based on incremental dynamic programming (IDP) with weekly steps is used, each step being evaluated by mixed integer linear programming (MILP) on an hourly basis. The model considers hourly water inflows and energy prices, limits on reservoir level and water discharge, power generation dependence on the available head, wear and tear costs of hydro units caused by power variations, start-up and shut-down costs of hydro units, and minimum environmental flows and maximum ramping rates. The main contribution of the proposed model is the consideration of the released flow as a second state variable to define the state diagram of the problem, with the aim of guaranteeing the continuity of flow between consecutive weeks and thus the fulfilment of MRR. The results obtained in a case study with a real plant are discussed. The inclusion of the released flow as state variable does not show a significant impact in the estimated annual revenue, but certain differences observed in some periods of the year might justify its consideration in shorter time horizons.