Angélica Casero, Laura G. Sánchez, Felicia Alfano
et al.
This study investigates the application of computational hemodynamic modeling, involving both FSI and CFD models, using SimVascular to simulate blood flow in the right pulmonary artery for patient-specific cardiovascular assessment. The artery’s three-dimensional geometry was reconstructed from a computed tomography (CT) image, and pressure measurements from a CardioMEMS™ device were used as clinical ground truth for validation. To represent the arterial hemodynamics, we initially formulated a fluid–structure interaction (FSI) approach to capture wall mechanics. However, given the high computational cost of fully patient-specific FSI simulations for routine clinical decision-making, we evaluated the validity of key simplifications by assuming rigid vessel walls coupled with a three-element Windkessel (3WK) model and applying a half-sine inflow waveform derived from the patient’s cardiac output. These simplifications yielded results with minimal error: the rigid-wall assumption introduced a 1.1% deviation, while the idealized waveform resulted in a 0.56 mmHg offset. Crucially, while wall rigidity was acceptable, we found that arterial compliance in the boundary conditions is non-negotiable; reducing the model to a pure resistance approach resulted in non-physiological pressures (130 mmHg). A subsequent parametric analysis examined how varying resistance (R) and compliance (C) distinctively alter the pressure waveform morphology. The results underscore the potential of combining remote monitoring data with validated computational simulations to deepen the understanding of cardiovascular dynamics and enhance diagnostic and therapeutic approaches for cardiovascular diseases.
Thermodynamics, Descriptive and experimental mechanics
The solar-periodic system is a completely self-contained space, with no singularity or boundaries, which timelessly regenerates preserving its initial states (origins) and completely described by Euler’s complex theory of holomorphic (complex-smooth-recurrent) functions, ever discovered. This unified theory is the basis of eternal existence furnishing the building blocks of reality and the solution for long-standing problem of Cartesian dualism. It demonstrates precisely how mind generates relative/temporary matter in a metastable (phasing) equilibrium through the quantum dual isomorphism (e, p) of light, mutually regenerating matter. Physically it manifests as the quantum recurrence at the three levels/scales: quantum chemical elements (Mendeleev’s law, atomic frozen spiral), molecular thermistors (thermal molecular spiral) and astronomical gravitational rotating bodies (global/integrated solar system of planets and satellites). The periodical chemical elements are the first 94 known to occur naturally on Earth, of which 36 are primordial making up “the permafrost”. These are elements from the p-block (including hydrogen and helium) of the periodic table, where their atomic structure has completely filled subshells preserving initial states are daily and monthly (Krypton) regenerating (24 hours-one day) ≅1 𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎 𝑚 𝑚𝑚𝑚𝑚𝑚𝑚 (𝑃𝑃𝑢𝑢)𝑔𝑔0 𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎 𝑛𝑛𝑛𝑛𝑛 𝑛𝑛𝑛𝑛𝑛𝑛 (𝑍𝑍). They genuinely have a dual character (two allotropes/states), owing to the primal quantum contact ((𝑒𝑒+𝑒𝑒2)1/4≡𝜋𝜋1/2). The molecular structures and astronomical body configurations, self-contained them, are regenerating after a year and respectively century following a binary gravitational rule, 𝑔𝑔02212=7 (𝑙𝑙𝑙𝑙𝑙𝑙𝑔 0=1), for critical mixtures, the so-called the relative peakedness or two soliton coherent distribution (phases). The solar regenerative system is a critical system in the sense that is “an autocatalytic thermomolecular reaction” regenerating its initial states only in strict conditions. In such a system the reaction products increase the rate of reaction and if the ratio of system surface to system volume is large, then the reaction products tend to escape at the boundaries of system. Contrary, if the surface to volume ratio is small then the rate of escape may be less than the rate of formation and the reaction rate may extinguish or re-ignite for a critical size where rate of production just equals the rate of removal. At such a critical size, given by Sobolev isoperimetric inequality (4𝜋𝜋𝜋𝜋 (𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎)≤𝑃𝑃2 (𝑝𝑝𝑝 𝑝 𝑝𝑝𝑝 𝑝𝑝𝑝 )), the reaction is self-sustaining and is going on for so-long time the rate of regeneration does not exceed the rate of production. The bases of the Eulerian quantum dual isomorphism of light which explain close relationship between quantum automorphic wary light and the solar timelessly regenerative system, in a photostationary (or frozen) equilibrium, are considered.
This paper presents three novel sufficient and necessary conditions for the admissibility of singular fractional-order systems (FOSs), a stabilization criterion, and a solution algorithm. The strict linear matrix inequality (LMI) stability criterion for integer-order systems is generalized to singular FOSs by using column-full rank matrices. This admissibility criterion does not involve complex variables and is different from all previous results, filling a gap in this area. Based on the LMIs in the generalized condition, the improved criterion utilizes a variable substitution technique to reduce the number of matrix variables to be solved from one pair to one, reflecting the admissibility more essentially. This improved result simplifies the programming process compared to the traditional approach that requires two matrix variables. To complete the state feedback controller design, the system matrices in the generalized admissibility criterion are decoupled, but bilinear constraints still occur in the stabilization criterion. For this case, where a feasible solution cannot be found using the MATLAB LMI toolbox, a branch-and-bound algorithm (BBA) is designed to solve it. Finally, the validity of these criteria and the BBA is verified by three examples, including a real circuit model.
The viscosities, η and refractive indices, nD of pure benzonitrile, methyl methacrylate, ethyl methacrylate, n‑butyl methacrylate and of their binary mixtures with benzonitrile as common component, covering the entire composition range were measured at temperatures (293.15, 298.15, 303.15, 308.15, 313.15 and 318.15) K and atmospheric pressure. The experimental data have been correlated using the Jouyban-Acree model to represents the composition and temperature dependence of these physicochemical properties. Using the experimental data, the deviations in viscosity, deviations in refractive index and deviations in molar refraction have been calculated. These excess properties were correlated by the Redlich-Kister equation. The variations of these deviation parameters with composition and temperature have been discussed terms of prevailing intermolecular interactions in these mixtures and the magnitude of interactions follow the order: MMA > EMA > BMA. Additionally, the thermodynamic parameters, Arrhenius activation energy and Gibbs free energy, enthalpy and entropy of activation of viscous flow have also been calculated and analyzed to describe the thermodynamics of viscous behaviour of these systems. Further, the η and nD of the binary mixtures were calculated theoretically using various empirical/semi-empirical viscosity relations and refractive index mixing rules, respectively, and the results were compared with the experimental data.
This paper investigates a general class of variable-kernel discrete delay differential equations (DDDEs) with integral boundary conditions and impulsive effects, analyzed using Caputo piecewise derivatives. We establish results for the existence and uniqueness of solutions, as well as their stability. The existence of at least one solution is proven using Schaefer’s fixed-point theorem, while uniqueness is established via Banach’s fixed-point theorem. Stability is examined through the lens of Ulam–Hyers (U-H) stability. Finally, we illustrate the application of our theoretical findings with a numerical example.
The leading-edge erosion of a wind turbine blade was tested using a whirling arm rain erosion tester, whose rotation rate is considerably higher than that of a full-scale wind turbine owing to the scale effect. In this study, we assessed the impact pressure of droplets on a wet surface of wind turbine blades using numerical simulation of liquid droplet impact by solving the Navier–Stokes equations combined with the volume-of-fluid method. This was conducted in combination with an estimation of liquid film thickness on the rotating blade using an approximate solution of Navier–Stokes equations considering the centrifugal and Coriolis forces. Our study revealed that the impact pressure on the rain erosion tester exceeded that on the wind turbine blade, attributed to the thinner liquid film on the rain erosion tester than on the wind turbine blade caused by the influence of centrifugal and Coriolis forces. This indicates the importance of correcting the influence of liquid-film thickness in estimating the impact velocity of droplets on the wind turbine blade. Furthermore, we demonstrated the correction procedure when estimating the impact velocity of droplets on the wind turbine blade.
Thermodynamics, Descriptive and experimental mechanics
Abstract Tides in the Arctic Ocean affect ocean circulation and mixing, and sea ice dynamics and thermodynamics. However, there is a limited network of available in situ tidal coefficient data for understanding tidal variability in the Arctic Ocean; e.g., the global TICON-3 database contains only 111 sites above 60°N and 21 above 70°N. At the same time, the presence of sea ice and latitude limits of satellite altimetry complicate altimetry-based retrievals of Arctic tidal coefficients. This leads to a reliance on ocean tide models whose accuracy depend on having sufficient in situ data for validation and assimilation. Here, we present a comprehensive new dataset of tidal constituents in the Arctic region, combining analyses of in situ measurements from tide gauges, ocean bottom pressure sensors and GNSS interferometric reflectometry. The new dataset contains 914 measurement sites above 60°N and 399 above 70°N, with each site being quality-assessed and expert guidance provided to help maximise the usage of the dataset. We also compare the dataset to recent tide models.
We explore in detail the structural, mechanical, and thermodynamic properties of a coarse-grained model of DNA similar to that recently introduced in a study of DNA nanotweezers [T. E. Ouldridge, A. A. Louis, and J. P. K. Doye, Phys. Rev. Lett. 134, 178101 (2010)]. Effective interactions are used to represent chain connectivity, excluded volume, base stacking, and hydrogen bonding, naturally reproducing a range of DNA behavior. The model incorporates the specificity of Watson-Crick base pairing, but otherwise neglects sequence dependence of interaction strengths, resulting in an "average base" description of DNA. We quantify the relation to experiment of the thermodynamics of single-stranded stacking, duplex hybridization, and hairpin formation, as well as structural properties such as the persistence length of single strands and duplexes, and the elastic torsional and stretching moduli of double helices. We also explore the model's representation of more complex motifs involving dangling ends, bulged bases and internal loops, and the effect of stacking and fraying on the thermodynamics of the duplex formation transition.
This article combines data from two previous reports together with new data dealing with the vaporization enthalpies and vapor pressures of a series of saturated and unsaturated fatty acid methyl ester(s) (FAME) by correlation gas chromatography. The work updates earlier results using newly proposed vaporization enthalpies for the saturated FAME used as standards in previous work. This update also provides some insight into the requirements necessary for appropriate column and standard selection for experiments using correlation gas chromatography. Vaporization enthalpies and vapor pressures for saturated FAME methyl heneicosanoate, methyl docosanoate, and methyl tetracosanoate are re-evaluated and together with proposed literature values for methyl tetradecanoate to methyl eicosanoate, are used to evaluate similar properties for a series of unsaturated fatty acid esters. Updated results on the vaporization enthalpies and vapor pressures of a number of unsaturated fatty acid methyl esters (FAME) found in marine oil are reported including several relatively reactive omega-3-polyunsaturated esters. Omega-3-FAME include methyl (9,12,15)Z-octadecatrienoate, methyl (5,8,11,14,17)Z-eicosapentaenoate, and methyl (4,7,10,13,16,19)Z-docosahexenoate among other unsaturated methyl esters. Also included in the study of the omega-3-unsaturated esters is the drug Vescepa®, ethyl (5,8,11,14,17)Z-eicosapentaenoate, a drug used to lower triglyceride levels.
Fethi Dridi, Safwan El Assad, Wajih El Hadj Youssef
et al.
In this paper, we come up with three secure chaos-based stream ciphers, implemented on an FPGA board, for data confidentiality and integrity. To do so, first, we performed the statistical security and hardware metrics of certain discrete chaotic map models, such as the Logistic, Skew-Tent, PWLCM, 3D-Chebyshev map, and 32-bit LFSR, which are the main components of the proposed chaotic generators. Based on the performance analysis collected from the discrete chaotic maps, we then designed, implemented, and analyzed the performance of three proposed robust pseudo-random number generators of chaotic sequences (PRNGs-CS) and their corresponding stream ciphers. The proposed PRNGs-CS are based on the predefined coupling matrix M. The latter achieves a weak mixing of the chaotic maps and a chaotic multiplexing technique or XOR operator for the output function. Therefore, the randomness of the sequences generated is expanded as well as their lengths, and divide-and-conquer attacks on chaotic systems are avoided. In addition, the proposed PRNGs-CS contain polynomial mappings of at least degree 2 or 3 to make algebraic attacks very difficult. Various experimental results obtained and analysis of performance in opposition to different kinds of numerical and cryptographic attacks determine the high level of security and good hardware metrics achieved by the proposed chaos system. The proposed system outperformed the state-of-the-art works in terms of high-security level and a high throughput which can be considered an alternative to the standard methods.
The thermodynamics of black holes in various dimensions are described in the presence of a negative cosmological constant which is treated as a thermodynamic variable, interpreted as a pressure in the equation of state. The black hole mass is then identified with the enthalpy, rather than the internal energy, and heat capacities are calculated at constant pressure not at constant volume. The Euclidean action is associated with a bridge equation for the Gibbs free energy and not the Helmholtz free energy. Quantum corrections to the enthalpy and the equation of state of the BTZ black hole are studied.