Universal Parameter Research Articles

Characterization of the flowability dynamics of granular material flowing down a narrow channel

The flowability of granular material is commonly determined from shear cell tests, but in the real world, the granular flow is quite different in many cases. For this paper, the flowabilities in a narrow channel of five different granular materials were investigated. The flow parameters of the granular flows were determined to classify the flowabilities. Granular flow surface velocities and flow heights and thicknesses were measured, and it was found that the mean shear rates in the linear portions of the velocity profiles increase with both flow rates and inclination. A universal parameter, the ratio of the sine of the inclination to the shear rate in the linear part of the velocity profile, is proposed as a constant. This constant is independent of particle properties. In addition, a flowability parameter, the ratio of the mean shear rate to the cosine of the inclination, is proposed to characterize the friction between the particles in the flowing granular material.

Galactic Rotation Curves in Conformal Scalar-Tensor Gravity

We show quantitatively that an exact solution of conformal scalar-tensor gravity can explain very well the galactic rotation curves for a sample of 104 galaxies without the need for dark matter or other exotic modification of gravity. The metric is an overall rescaling of the Schwarzschild-de Sitter space-time as required by Weyl conformal invariance, which has to be spontaneously broken, and the velocity of the stars depends only on two fixed universal parameters. Using the Monte Carlo Markov Chain (MCMC) method, we make a fit of the observational rotation curves in order to get the mass-to-light ratio for each galaxy. Finally, we analytically compare our model with the modified Newtonian dynamics (MOND) and the metric skew tensor gravity (MSTG) showing that the three theories have a very different behavior at very large distances.

PHRASEOSEMANTIC FIELD “HUMAN HEALTH” IN MANSI AND RUSSIAN LANGUAGES: COMPARATIVE ASPECT

The article considers phraseological units (PU) of the Mansi and Russian languages as lexical means of description of a person's appearance and his state within the framework of the phrase-semantic field (PSF) “human health” in the context of the linguistic and cultural content of national pictures of the world; it reveals the reflection of folk representations about the image of a healthy and unhealthy person. The article defines the universal and specific parameters of imagery of metaphorsduring description of the image of a healthy and unhealthy person. It describes the components of semantics and figurative internal forms that create the national and cultural specificity of the studied PU. The research materials are the PU of the Northern dialect of the Mansi language, metaphors and expressions that represent the appearance and state of a person within the framework of the PSF “human health”, as well as Russian PU extracted by continuous sampling from phraseological dictionaries.

Computed tomography-assisted morphological assessment of the components of the temporomandibular joint – a pilot study

Introduction. Temporomandibular joint (TMJ) disorders are a common diagnostic problem. No universal radiological parameter of the analysis was introduced. Aim. Comparison of values of selected radiological parameters between asymptomatic patients and those with the TMJ arthropathy. Material and methods. Retrospective analysis of CT scans of patients of the Department of Dental and Maxillofacial Radiology and the Department of Cranio-Maxillofacial Surgery, Oral Surgery and Implantology, Medical University of Warsaw. Patients were divided into two groups: 1. without TMJ disorders, 2. with TMJ dysfunction symptoms. Following parameters of heads of mandible were analyzed bilaterally: shape, anteroposterior and lateromedial dimensions, the distance between lateral points of both heads (HL-HR), distance between a head and the mandibular fossa. The angle between the horizontal axis of the head of mandible and the line drawn by posterior points of heads of mandible was measured. Results. The most common type of the head of mandible in group 1 (40 patients; 13 women, 27 men) was convex (14 patients), in group 2 (16 patients; 14 women, 2 men) – plane (8 patients). Significant differences between groups were obtained for: GL-GP (group 1 – 120.35 mm, group 2 – 115.4 mm), dimensions of heads of mandible: lateromedial – 19.7 mm, 18.14 mm, anteroposterior – 8.03 mm, 7.04 mm for group 1 and 2, respectively. Conclusions. Computed tomography allowed for an accurate analysis of the TMJ components. Measurements of structures discussed in this work should be a part of the diagnosis of patients with TMJ dysfunction.

Universal scaling parameter for a counter jet drag reduction technique in supersonic flows

The reduction in aerodynamic drag by injecting a gaseous jet from the nose of a blunt body into a supersonic stream is investigated numerically. The penetration of the jet into the supersonic flow modifies the shock structure around the body and creates a low pressure recirculation zone, thereby decreasing the wave drag significantly. Combining various theoretical estimates of different flow features and numerical simulations, we identify a universal parameter, called the jet to freestream momentum ratio (RmA), which uniquely governs the drag on the blunt body. The momentum ratio fundamentally decides the penetration of the jet as well as the extent of low pressure envelope around the body. In addition, various influencing parameters reported in the literature are reviewed for different steady jet flow conditions. Furthermore, their limitations in regulating the flowfield are explained by correlating the facts with the jet to freestream momentum ratio. We perform the simulations for various combinations of physical and flow parameters of the jet and the freestream to show a universal dependence of drag on the momentum ratio.

Entanglement in coupled kicked tops with chaotic dynamics.

The entanglement of eigenstates in two coupled, classically chaotic kicked tops is studied in dependence of their interaction strength. The transition from the noninteracting and unentangled system toward full random matrix behavior is governed by a universal scaling parameter. Using suitable random matrix transition ensembles we express this transition parameter as a function of the subsystem sizes and the coupling strength for both unitary and orthogonal symmetry classes. The universality is confirmed for the level spacing statistics of the coupled kicked tops and a perturbative description is in good agreement with numerical results. The statistics of Schmidt eigenvalues and entanglement entropies of eigenstates is found to follow a universal scaling as well. Remarkably, this is not only the case for large subsystems of equal size but also if one of them is much smaller. For the entanglement entropies a perturbative description is obtained, which can be extended to large couplings and provides very good agreement with numerical results. Furthermore, the transition of the statistics of the entanglement spectrum toward the random matrix limit is demonstrated for different ratios of the subsystem sizes.

Die-sinking EDM of Al6061-T6: interactions between process parameters, process performance, and surface characteristics

Die-sinking electrical discharge machining (EDM) is the principal method used to machine critical components made of Al6061 alloy for space applications. Geometrical precision and surface roughness are among the most important acceptance criteria for these machined parts. The purpose of this research work is to identify the most significant parameters affecting the material removal rate (MRR), the electrode radius wear rate (EWR), and the surface roughness (Sa) when machining Al6061-T6 aluminum alloy by die-sinking electrical discharge machining and to use this knowledge in future work to generate accurate predictive models. To this end, ten universal machining parameters were selected, and using a Plackett–Burman Design of Experiments (DOE) approach, their influence and relative impact on MRR, EWR, and Sa were calculated and validated using experiments. A comprehensive Analysis of Variance (ANOVA) was then conducted based on the obtained results. It was found that the discharge current, the discharge duration, and the system voltage significantly affect the MRR, while these same three parameters plus the delay between two series of discharges significantly affect the EWR. The surface roughness was affected by the discharge current, the discharge duration, the voltage, the delay between two discharges, and the delay between two series of discharges. The obtained results were analyzed in terms of the relationship between energy input during machining and the surface modification of the material.

Screening Deep Eutectic Solvents for CO2 Capture With COSMO-RS.

In this work, 502 experimental data for CO2 solubilities and 132 for Henry's constants of CO2 in DESs were comprehensively summarized from literatures and used for further verification and development of COSMO-RS. Large systematic deviations of 62. 2, 59.6, 63.0, and 59.1% for the logarithmic CO2 solubilities in the DESs (1:2, 1:3, 1:4, 1:5), respectively, were observed for the prediction with the original COSMO-RS, while the predicted Henry's constants of CO2 in the DESs (1:1.5, 1:2, 1:3, 1:4, 1:5) at temperatures ranging of 293.15–333.15 K are more accurate than the predicted CO2 solubility with the original COSMO-RS. To improve the performance of COSMO-RS, 502 data points of CO2 solubility in the DESs (1:2, 1:3, 1:4, 1:5) were used for correcting COSMO-RS with a temperature-pressure dependent parameter, and the CO2 solubility in the DES (1:6) was predicted to further verify the performance of the corrected model. The results indicate that the corrected COSMO-RS can significantly improve the model performance with the ARDs decreasing down to 6.5, 4.8, 6.5, and 4.5% for the DESs (1:2, 1:3, 1:4, and 1:5), respectively, and the corrected COSMO-RS with the universal parameters can be used to predict the CO2 solubility in DESs with different mole ratios, for example, for the DES (1:6), the corrected COSMO-RS significantly improves the prediction with an ARD of 10.3% that is much lower than 78.2% provided by the original COSMO-RS. Additionally, the result from COSMO-RS shows that the σ-profiles can reflect the strength of molecular interactions between an HBA (or HBD) and CO2, determining the CO2 solubility, and the dominant interactions for CO2 capture in DESs are the H-bond and Van der Waals force, followed by the misfit based on the analysis of the predicted excess enthalpies.

Confined elasticae and the buckling of cylindrical shells

Abstract For curves of prescribed length embedded into the unit disk in two dimensions, we obtain scaling results for the minimal elastic energy as the length just exceeds 2 ⁢ π {2\pi} and in the large length limit. In the small excess length case, we prove convergence to a fourth-order obstacle-type problem with integral constraint on the real line which we then solve. From the solution, we obtain the energy expansion 2 ⁢ π + Θ ⁢ δ 1 3 + o ⁢ ( δ 1 3 ) {2\pi+\Theta\delta^{\frac{1}{3}}+o(\delta^{\frac{1}{3}})} when a curve has length 2 ⁢ π + δ {2\pi+\delta} and determine first order coefficient Θ ≈ 37 {\Theta\approx 37} . We present an application of the scaling result to buckling in two-layer cylindrical shells where we can determine an explicit bifurcation point between compression and buckling in terms of universal constants and material parameters scaling with the thickness of the inner shell.

Entropy and Mass Distribution in Disc Galaxies

The relaxed motion of stars and gas in galactic discs is well approximated by a rotational velocity that is a function of radial position only, implying that individual components have lost any information about their prior states. Thermodynamically, such an equilibrium state is a microcanonical ensemble with maximum entropy, characterised by a lognormal probability distribution. Assuming this for the surface density distribution yields rotation curves that closely match observational data across a wide range of disc masses and galaxy types and provides a useful tool for modelling the theoretical density distribution in the disc. A universal disc spin parameter emerges from the model, giving a tight virial mass estimator with strong correlation between angular momentum and disc mass, suggesting a mechanism by which the proto-disc developed by dumping excess mass to the core or excess angular momentum to a satellite galaxy. The baryonic-to-dynamic mass ratio for the model approaches unity for high mass galaxies, but is generally <1 for low mass discs, and this discrepancy appears to follow a similar relationship to that shown in recent work on the Radial Acceleration Relation (RAR). Although this may support Modified Newtonian Dynamics (MOND) in preference to a Dark Matter (DM) halo, it does not exclude undetected baryonic mass or a gravitational DM component in the disc.

Superstatistical properties of the one-dimensional Dirac oscillator

In this paper, we consider the thermal properties of one-dimensional Dirac in the framework of the theory of superstatistics where the probability density f(β) follows χ2−superstatistics (=Tsallis statistics or Gamma distribution). Under the approximation of the low-energy asymptotics of superstatistics, the partition function, at first, has been calculated by using both Mellin Transformation and Zeta function. This approximation leads to a universal parameter q for any superstatistics, not only for Tsallis statistics. By using the desired partition function, all thermal properties have been obtained in terms of the parameter q. As an application, we extend this concept to the case of Graphene: the reason of this choice is due the existence of an exact mapping about the Dirac oscillator and the compound in question.

Topological Climate Change

This article presents a bifurcation analysis of a simple Energy Balance Model (EBM) of the Earth’s climate, which suggests that topological change has occurred in the paleoclimate history of the Earth. In the theory of dynamical systems, two systems that are topologically equivalent have solutions with the same qualitative behavior. A change in the topological equivalence class, as parameters are varied, is called a bifurcation. Thus, a bifurcation demarcates a significant change in the behavior of the solutions of a dynamical system. If that system represents climate, then that topological change may represent an abrupt transformation of the climate, occurring even with a very small change in the forcing parameters. In this paper, the existence of a cusp bifurcation is proven in a climate EBM. The existence of this cusp bifurcation implies the co-existence of two distinct stable equilibrium climate states (bistability), as well as the existence of abrupt transitions between these two states (fold bifurcations) in the EBM. These transitions are dependent on the past history of the system (hysteresis). The two universal unfolding parameters for the cusp bifurcation have been determined as functions of the relevant physical parameters. These ideas lead to the proposal of a new explanation for the so-called warm equable climate problem of the mid-Cretaceous and early Eocene. The analysis presented here implies that the mid-Cretaceous and early Eocene climate systems are topologically equivalent to each other, but they are not topologically equivalent to the preindustrial modern climate. The transition from the warm, equable paleoclimate to today’s cooler nonequable climate occurs via fold (or saddle-node) bifurcations in the EBM, which correspond to the Eocene-Oligocene Transition (EOT) at the south pole and the Pliocene-Pleistocene Transition (PPT) at the north pole, in the paleoclimate record of Earth.

Interchange‐turbulence‐based radial transport model for SOLPS‐ITER: A COMPASS case study

AbstractMean‐field plasma edge transport codes such as SOLPS‐ITER heavily rely on ad‐hoc radial diffusion coefficients to approximately model anomalous transport. Such coefficients are experimentally determined and vary between different machines, and also depend on the operational regime and plasma location within the same device. Therefore, to match experimental data the modeller is required to manually tune several free parameters in expensive simulations, and the code's predictive capabilities are significantly downgraded. As a solution, a new model has been developed for SOLPS‐ITER, solving an additional transport equation for the turbulent kinetic energy k, derived by consistently time‐averaging the Braginskii equations, and including a diffusive closure for the anomalous particle flux. This closure model relates the anomalous diffusion coefficient to the local k value. The resulting equation structure and its closure are inspired by TOKAM2D isothermal interchange turbulence simulation results. Within this model, fewer and hopefully more universal free parameters are retained, thus improving the code's predictive capabilities. The new model has been tested on a COMPASS case for which upstream plasma profiles were available. Experimental data and a reference solution, obtained by matching the profiles through manual tuning of radial diffusivities, have been used to estimate the parameters of our new transport model. A ballooned particle diffusivity profile is retrieved by the new radial transport model, thanks to the proposed interchange drive. The obtained upstream profiles qualitatively agree with the experiment and prove the new model is a promising first attempt to be further refined.

Alternative coalescence model for deuteron, tritium, helium-3 and their antinuclei

Antideuteron and antihelium nuclei have been proposed as a detection channel for dark matter annihilations and decays in the Milky Way, due to the low astrophysical background expected. To estimate both the signal for various dark matter models and the astrophysical background, one employs usually the coalescence model in a Monte Carlo framework. This allows one to treat the production of antinuclei on an event-by-event basis, taking thereby into account momentum correlations between the antinucleons involved in the process. This approach lacks however an underlying microscopic picture, and the numerical value of the coalescence parameter obtained from fits to different reactions varies considerably. Here we propose instead to combine event-by-event Monte Carlo simulations with a microscopic coalescence picture based on the Wigner function representations of the produced antinuclei states. This approach allows us to include in a semi-classical picture both the size of the formation region, which is process dependent, and momentum correlations. The model contains a single, universal parameter which is fixed by fitting the production spectra of antideuterons in proton-proton interactions, measured at the Large Hadron Collider. Using this value, the model describes well the production of various antinuclei both in electron-positron annihilation and in proton-proton collisions.

Exergy graph-based fault detection and isolation of a gas-to-liquids process

With the sheer size of modern process plants, the Fault Detection and Isolation (FDI) field continues to gain popularity. FDI is a sophisticated concept which aims to detect and isolate anomalies that occur within a plant to avoid losses of personnel, damages to the environment, and financial implications. It does so in a way which is more direct, efficient and safer than what human operators are capable of. One approach to FDI is to consider the exergy characterisation of a system. By describing the exergy of the system units and streams, in this case a gas-to-liquids (GTL) process plant, the various process variables are encapsulated under a universal energy-domain parameter. The advantage of this being that it can describe the physical states as well as the chemical characteristics of the process. Previous work which utilised exergy characterisation along with a fixed-threshold approach showed promise. This study however, shows that the approach falls short when presented with 3 % faults. These results motivated the investigation of utilising attributed graphs, which package exergy data into a framework that preserves structural information of the plant. The usefulness of finding similarities (called graph matching) between the graphs constructed of operational conditions and pre-collected fault conditions to detect and isolate faulty conditions, is demonstrated. The technique performs well when considering fault magnitudes bigger than 8 % but deteriorates when applied to smaller, 3 % faults. The poor performance could be ascribed to the graph matching aspect, which is described by a single distance value that discards dimensionality. Future work will therefore look into the graph matching technique specifically, aiming to retain more informative dimensions.

Reverse droop control-based smooth transfer strategy for interface converters in hybrid AC/DC distribution networks

Hybrid AC/DC distribution networks are promising candidates for future applications due to rapid advancement in power electronics technology. They use interface converters (IFCs) to link DC and AC distribution networks. However, they possess drawbacks of the AC voltage and frequency offsets when transferring from grid-tied to islanding modes. To tackle this problem, this paper proposes a simple but effective strategy based on reverse droop method. Initially, the power balance equation of the distribution system is derived, it reveals that the cause of voltage and frequency offsets is the mismatch between IFC output power and the rated load power. Then, the reverse droop control is introduced into the IFC controller. By using a voltage-active power / frequency-reactive power (U-P /f-Q) reverse droop loop, the IFC output power enables adaptive tracking of the rated load power. Therefore, the AC voltage offset and frequency offset are suppressed during the transfer process of operational modes. In addition, the universal parameter design method is discussed based on the stability limitations of the control system and the voltage quality requirements of AC critical loads. Finally, simulation and experimental results clearly validate the proposed control strategy and parameter design method.

New approaches for evaluation of soil health, sensitivity and resistance to degradation

Assessment of soil health requires complex evaluation of properties and functions responsible for a broad range of ecosystem services. Numerous soil quality indices (SQI) have been suggested for the evaluation of specific groups of soil functions, but comparison of various SQI is impossible because they are based on a combination of specific soil properties. To avoid this problem, we suggest an SQI-area approach based on the comparison of the areas on a radar diagram of a combination of chemical, biological and physical properties. The new approach is independent of the SQI principle and allows rapid and simple comparison of parameter groups and soils. Another approach analyzing the resistance and sensitivity of properties to degradation is suggested for a detailed evaluation of soil health. The resistance and sensitivity of soil properties are determined through comparison with the decrease of soil organic carbon (SOC) as a universal parameter responsible for many functions. The SQI-area and resistance/sensitivity approaches were tested based on the recovery of Phaeozems and Chernozems chronosequences after the abandonment of agricultural soils. Both the SQI-area and the resistance/sensitivity approaches are useful for basic and applied research, and for decision-makers to evaluate land-use practices and measure the degree of soil degradation.

Thermophysical Properties of Volatile Products of Low-Temperature Pyrolysis of Wood Biomass

It is shown that the quantity of mass loss can be used as a universal parameter to describe the thermophysical properties of volatile products released during low-temperature pyrolysis of biomass. The results of calculations of the specific heat, heat of combustion, stoichiometric coefficient, density, and adiabatic combustion temperature of the volatile products of two types of wood biomass are presented.

Structures of inverse jet flames stabilized on a coaxial burner

In this study we investigate different parameters used for mapping global flame structures and identify the most universal in terms of comparing flames emerging from different geometrical burner arrangements. Simultaneously the study was carried out to determine the discharge conditions yielding the blue flame of a high degree of partial premixing, and to examine the instantaneous local flame structures and mixing in the blue torch area under these conditions. In order to decouple velocity ratio and global equivalence ratio (referring to the mass flow rate of air and methane), as well as the jet velocity and Reynolds number, two different centre air nozzle diameters were studied. The results clearly indicated that the centre jet Reynolds number and global equivalence ratio are more universal parameters for inverse flame characterization than jet velocity and velocity ratio. OH-PLIF (planar laser-induced fluorescence), hot- and cold-flow acetone-PLIF were performed to provide additional information on instantaneous local flame structures and mixing in the blue torch area of the flame resembling a partially premixed flame. The PLIF results indicated that in the area of the blue torch, air and gas are well mixed by shear layer-generated vortices, and turbulences, which at this position are strongly present.

Primordial power spectra for curved inflating universes

Exact numerical primordial primordial power spectra are computed and plotted for the for the best-fit Planck 2018 curved universe parameters. It is found that the spectra have generic cut-offs and oscillations within the observable window for the level of curvature allowed by current CMB measurements and provide a better fit to current data. Derivations for the Mukhanov-Sasaki equation for curved universes are presented and analysed, and theoretical implications for the quantum and classical initial conditions for inflation are discussed within the curved regime.