Article
Biochemistry & Molecular Biology
Paul Ecker, Markus Pekovits, Tsvetan Yorov, Bahram Haddadi, Benjamin Lukitsch, Martin Elenkov, Christoph Janeczek, Christian Jordan, Margit Gfoehler, Michael Harasek
Summary: This study used experimentally validated computational fluid dynamics simulations to investigate transverse flow within fiber packings of circular and microstructured fiber geometries, and calculated the local Sherwood number on the membrane surface for qualitative comparison of gas exchange capacities in low-velocity areas caused by the microstructured geometries. Adverse flow structures lead to a tradeoff between increased surface area and mass transfer.
Article
Engineering, Environmental
Zhenyu Zhao, Koenraad Muylaert, Anthony Szymczyk, Ivo F. J. Vankelecom
Summary: This study highlights the significant impact of membrane charge and surface pattern on membrane filtration performance, especially in terms of microalgae harvesting efficiency. By optimizing the membrane pattern and charge, it is possible to enhance the clean water permeance and microalgae harvesting efficiency.
Article
Mathematics, Applied
Usama Kadri, Zhan Wang
Summary: This study discusses the three-dimensional radial propagation of wave disturbances over a slightly compressible fluid of constant depth, focusing on resonant triads with two gravity modes and one acoustic mode. Derivation of evolution equations is achieved by approximating radial solutions with cosine functions in inner and outer regions. When interaction occurs in the inner region of all modes, amplitude evolution equations are similar to the two-dimensional case, but focusing of one gravity mode and de-focusing of the other is observed when involving an inner region of the acoustic mode and outer regions of gravity modes.
COMMUNICATIONS IN NONLINEAR SCIENCE AND NUMERICAL SIMULATION
(2021)
Article
Engineering, Civil
J. C. Monge, J. L. Mantari
Summary: This paper presents an exact solution for the static analysis of magneto-electro-elastic simply supported shallow shell panels through deriving mechanical equations and electro-magnetic governing equations, solving them using different methods, and obtaining numerical results consistent with existing literature.
ENGINEERING STRUCTURES
(2021)
Article
Mining & Mineral Processing
S. Serdyukov, A. Azarov, L. A. Rybalkin, A. Patutin
Summary: The article discusses the theoretical and experimental results on the propagation of hydraulic fractures around an extended cylindrical cavity in an isotropic elastic medium. It illustrates the influence of factors such as the fracture initiator, cavity spacing, strength, and compression of the medium on the curvature and volume of the created fractures. The study describes the main types and conditions of the created fractures, and demonstrates the reliability and applicability of numerical research in the design of hydraulic fracturing at short distances from underground openings and structures through physical simulation and full-scale experiments.
JOURNAL OF MINING SCIENCE
(2021)
Article
Mechanics
Vineet Nair, Ishan Sharma, V. Shankar
Summary: In this study, the equilibrium of an axisymmetric system of sessile and pendent drops on pre-stretched nonlinear elastic membranes is investigated. The non-unique equilibrium solutions due to force balance alone are shown, and the uniqueness of the equilibrium solution is determined by requiring the continuity of meridional stretches across the three-phase contact circle. The equilibrium configurations of the drop-membrane system are computed for a range of drop volumes and membrane pre-tensions using a special class of nonlinear elastic materials - I2 materials. This work enables applications such as using the system as an elastocapillary probe for membrane pre-tension and suggesting an experimental protocol for measuring the membrane's surface properties.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Chemistry, Physical
Leanne M. Friedrich, Jonathan E. Seppala
Summary: Embedded 3D printing enables the manufacture of complex, custom structures, and material selection, ink rheology, support rheology, and surface tension all affect print quality. At low viscosities, surface tension controls filament morphology, while Herschel-Bulkley support fluids produce more stable filaments.
Article
Thermodynamics
Yan Cao, Hamdi Ayed, Hussein Togun, Hajar Alias, Souhail Mohamed Bouzgarrou, Makatar Wae-hayee, Riadh Marzouki
Summary: This study numerically investigated the effects of local thermal non-equilibrium porous media on the melting process of paraffin with the melting temperature of 33 degrees C. The presence of aluminum foam with different porosities and temperature differences was found to influence the melting fraction and time significantly.
CASE STUDIES IN THERMAL ENGINEERING
(2021)
Article
Chemistry, Physical
Priyanka Iyer, Gerhard Gompper, Dmitry A. Fedosov
Summary: This study investigates the behavior of active vesicles through simulations, analyzing the deformations of membranes, clustering and mobility of SPPs. The results reveal a feedback mechanism between membrane curvature, particle clustering, and changes in vesicle shape due to SPP activity.
Article
Multidisciplinary Sciences
Md. Arif Kamal, Anirban Polley, P. K. Shabeeb, V. A. Raghunathan
Summary: We present two binary lipid-sterol membrane systems that exhibit fluid-fluid coexistence. The partial phase diagrams of the binary mixtures, determined from experimental studies, show closed-loop fluid-fluid immiscibility gaps. Computer simulations suggest that this unusual phase behavior is a result of the different orientations of the oxysterol molecules in the membrane depending on the temperature.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2023)
Article
Chemistry, Physical
Defeng Yan, Yuhui Wang, Jiyu Liu, Danyang Zhao, Pingmei Ming, Jinlong Song
Summary: A novel method was proposed in this study to prepare conical, cylindrical, and inverted conical pillars using meniscus-confined electrochemical 3D printing. Pillar arrays with excellent superhydrophobicity were successfully fabricated on Cu substrates, enriching the theory and technology for preparing superhydrophobic pillars with variable diameters.
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
(2021)
Article
Chemistry, Physical
Yueming Sun, Konstantin G. Kornev
Summary: This passage discusses the shape transition of equilibrium droplets on cylindrical fibers, proposing two types of droplets: barreled and clamshell droplets. A series of experiments were conducted to analyze the shape of droplets and the results showed that the shape transition significantly depends on the method of drop formation and contact angle hysteresis. The experimental results can be used in various engineering applications.
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
(2023)
Article
Multidisciplinary Sciences
Neelam Choudhary, Narveen Kumar, Elena Strelnikova, Vasil Gnitko, Denys Kriutchenko, Kyryl Degtyariov
Summary: This paper focuses on studying liquid vibrations in rigid circular cylindrical shells with internal flexible membranes. The incompressible and irrotational motion of fluid is considered, and boundary value problems for velocity potential are formulated to analyze the influence of membrane deflection and installation height on vibration frequencies. Both numerical and analytical methods are used to obtain solutions and evaluate the impact of various parameters on the system dynamics.
JOURNAL OF KING SAUD UNIVERSITY SCIENCE
(2021)
Article
Mechanics
Heiko Topol, Hadi Asghari, Marcus Stoffel, Bernd Markert, Jose Merodio
Summary: This article investigates the process of bubbling and bifurcation in a cylindrical membrane consisting of isotropic ground substance and fibers. It finds that material properties, fiber pre-stretch, fiber dispersion, and loading have significant effects on the initiation and post-bifurcation behavior.
EUROPEAN JOURNAL OF MECHANICS A-SOLIDS
(2023)
Article
Mechanics
Yueming Sun, Alexander V. V. Bazilevsky, Konstantin G. G. Kornev
Summary: With the development of nanotechnology, nanofibrous materials have gained attention in fluidic engineering. This study aims to categorize the possible axisymmetric configurations of droplets on fibers, introducing nodoidal apple-like droplets and unduloidal droplets. The existing theory of axisymmetric droplets on fibers is enriched by these new morphological configurations. The theory is experimentally confirmed and has potential applications in nanofiber-based fluidic devices and drop-on-demand technologies.
Article
Mathematics, Applied
Svetoslav G. Nikolov, Vassil M. Vassilev
Summary: In this work, a three-dimensional autonomous system of nonlinear ordinary differential equations is studied, which is a generalization of the Hopf-Langford system and equivalent to the nonlinear force-free Duffing oscillator. The system is found to be completely integrable in three special cases, with general solutions expressed in explicit analytical form. This allows for a detailed characterization of the dynamics of the systems.
COMMUNICATIONS IN NONLINEAR SCIENCE AND NUMERICAL SIMULATION
(2021)
Article
Mathematics, Applied
Vasyl Kovalchuk, Ivailo Mladenov
Summary: The mechanics of incompressible test bodies moving on spheres are generalized to lambda-spheres, with a derived parametrization and discussion of geodetic motion and specific geodesic solutions for meridians.
MATHEMATICAL METHODS IN THE APPLIED SCIENCES
(2022)
Article
Mathematics, Applied
Vasyl Kovalchuk, Ivailo M. Mladenov
Summary: A new reference model approximating the actual shape of the Earth is proposed, based on lambda-spheres as an alternative to rotational ellipsoids. The z-coordinate of the lambda-spheres is expressed concisely using incomplete elliptic integrals. Geodesic equations on the lambda-spheres are derived and solved analytically, resulting in three types of geodesics. Conditions for obtaining closed slant geodesics are found, and a comparison with the popular ellipsoidal reference models is presented.
MATHEMATICAL METHODS IN THE APPLIED SCIENCES
(2023)
Article
Mathematics
Vladimir Pulov, Magdalena D. Toda, Vassil M. Vassilev, Ivailo M. Mladenov
Summary: This article presents a comparative study of Kiepert's trefoil and its related curves, and solves some previously unsolved problems. The main goal of the paper is to characterize the general solution of the equation governing this curve's family of curves by involving elliptic functions and elastica theory.
Article
Mathematics
Vasyl Kovalchuk, Ivailo M. Mladenov
Summary: In this paper, a new reference model is presented to approximate the shape of the Earth. The model, called lambda-spheres, is based on the concept of deformed spheres with the parameter lambda. The explicit solutions for loxodromes on these surfaces are obtained, and the direct and inverse problems for loxodromes are formulated and solved. The proposed reference model is evaluated and compared with the existing ellipsoidal and spherical models using the values of the semi-major axis and quarter-meridian of the Earth.
Article
Mathematics
Vasyl Kovalchuk, Vladimir I. Pulov, Ivailo M. Mladenov
Summary: In this paper, explicit formulas for the geometric characteristics of a Mylar balloon and the mechanical moments of both solid and hollow balloons are presented. The formulas are derived using recursive relationships among elliptic integrals and expressed in terms of fundamental mathematical constants such as pi, lemniscate constant, and Gauss's constant G. The periodicity modulo 4 in the final formulas for the moments is investigated and illustrated using tables, graphics, and connections to other fundamental areas.
Article
Physics, Mathematical
Clementina D. Mladenova, Ivailo M. Mladenov
Summary: Despite the lack of clear relationships with measurable parameters, there has been a recent development in providing geometrical models of egg shapes based on Perseus spirics and Cassinian ovals. New explicit formulas for the volumes, surface areas, and curvatures of avian eggs have been derived and compared with experimental data.
JOURNAL OF GEOMETRY AND SYMMETRY IN PHYSICS
(2023)
Article
Physics, Mathematical
Svetoslav G. Nikolov, Vassil M. Vassilev
Summary: The aim of this paper is to investigate the integrable cases of a compound pendulum system consisting of a rider and a swing. Our analytical calculations reveal that this system has two integrable cases when the dumbbell lengths and point-masses meet certain conditions, and when the gravitational force is neglected.
JOURNAL OF GEOMETRY AND SYMMETRY IN PHYSICS
(2023)
Article
Mathematics, Applied
Svetoslav G. Nikolov, Vassil M. Vassilev
Summary: This paper discusses the analysis and computations of the transition from chaos to hyperchaos (or vice versa) in the Rossler-Nikolov-Clodong O (RNC-O) hyperchaotic system. The research is motivated by previous analysis of hyperchaotic transitional regimes in the RNC-O system and recent results from other researchers. The analysis and numerical simulations demonstrate that the transition from chaos to hyperchaos in the RNC-O system is accompanied by a change in equilibrium type, resulting in a large hyperchaotic attractor. The study also shows that a zero-Hopf bifurcation is not possible for this system, and identifies two families of exact solutions when the system divergence is constant.
Article
Physics, Mathematical
Clementina D. Mladenova, Ivailo M. Mladenov
Summary: The explanation of perfect forms in nature has been of great interest throughout history. However, current parametric descriptions of shapes, such as eggs, lack clear relationships with measurable parameters and rely solely on empirical formulas. In this study, we explore a geometric model proposed by G. Brandt, based on a fourth-order plane algebraic curve, and derive several parameterizations. The most fascinating one is the uniformization of the curve using Jacobian elliptic functions. Comparisons with experimental results have been made, but further investigation is needed.
JOURNAL OF GEOMETRY AND SYMMETRY IN PHYSICS
(2023)
Article
Physics, Mathematical
Clementina D. Mladenova, Ivailo M. Mladenov
Summary: This paper presents the dynamical orbits of the harmonic oscillator potential in the plane as ellipses, and proves that the locus of the focuses of these ellipses are Cassinian ovals. Several explicit analytic parameterizations are also provided, which can clearly distinguish the roles of size and shape.
JOURNAL OF GEOMETRY AND SYMMETRY IN PHYSICS
(2022)
Article
Physics, Mathematical
Ivailo M. Mladenov
Summary: A large number of explicit formulas that parameterize any type of spiric sections are derived from first principles.
JOURNAL OF GEOMETRY AND SYMMETRY IN PHYSICS
(2022)
Proceedings Paper
Mathematics, Applied
Clementina D. Mladenova, Ivailo M. Mladenov
Summary: Despite their importance, symplectic groups are not as popular as orthogonal groups possibly due to their more complex algebraic structures. However, it has been shown that in some sense symplectic groups can be represented by even dimensional symmetric matrices.
PROCEEDINGS OF THE TWENTY-SECOND INTERNATIONAL CONFERENCE ON GEOMETRY, INTEGRABILITY AND QUANTIZATION
(2021)
Proceedings Paper
Mathematics, Applied
Vladimir Pulov, Ivailo M. Mladenov
Summary: The article presents highly rich two/three parametric families of non-bending rotational surfaces in the three dimensional Euclidean space, along with their natural classifications and explicit parameterizations. By varying parameters, the evolution of these surfaces can be traced and visualized through their topological transformations, leaving deeper questions about their metrical properties, mechanical applications, etc. for future explorations.
PROCEEDINGS OF THE TWENTY-SECOND INTERNATIONAL CONFERENCE ON GEOMETRY, INTEGRABILITY AND QUANTIZATION
(2021)
