Hasil untuk "Analytic mechanics"

Riddhesh Nitin Kumtakar, Nitish Umang, Gary R. Kocis et al.

The problem of packing cases in three-dimensional space in a space-efficient manner is a challenging optimization problem that has wide application in supply-chain and logistics planning across various industries where physical products must be loaded and packed for storage and/or shipped to different destination locations. This work explores the use of matheuristic approaches to solve the 3D container loading problem to obtain high-quality loading plans in reasonable computation time for different levels of heterogeneity in the product mix. In our problem of interest, cuboidal cases must be arranged in a large cuboidal container, such as a shipper or gaylord box, allowing for two different case orientations around the vertical axis. We use a number of synergistic objectives to maximize space utilization while ensuring that items belonging to the same product SKU are preferentially placed together. We test and compare different solution methods, including full-space and decomposition-based ones, for placing items in 2D or 3D space. The decomposition methods use mathematical programming models in combination with embedded heuristics and construct a complete solution in three-dimensional space in an iterative manner. Results indicate that the 2D successive layer packing method is the most viable approach when considering solution quality and computational efficiency.

M.I. Bekenov, A. Mamyraly, A. Kassatova et al.

In this paper, we study classes of models of a first-order language L with a countable signature σ. For a model A, let Th(A) denote the set of all sentences of L that are true in A, called the elementary type of A. The cardinality of the set T of all elementary types of the signature σ does not exceed the continuum. The product of elementary types of models A and B is defined by Th(A) · Th(B) = Th(A × B), where A × B is the Cartesian product of A and B. Infinite products, ultraproducts, and ultrapowers of elementary types with respect to an ultrafilter D are defined analogously. This yields an algebra hT,·i, which is a commutative semigroup with identity and zero. A binary absorption (recognition) relation is introduced in this semigroup. An elementary type N absorbs an elementary type M if N · M = N. This notion leads to the concept of a formula-definable class of models. Formula-definable classes are closed under ultraproducts as well as finite and infinite direct products; they are idempotently formula-definable and axiomatizable. Varieties and quasivarieties are also considered. All varieties form formula-definable classes of models. Examples of a formula-definable class of models and of a class that is not formula-definable are given. An example of a formula-definable quasivariety that is not a variety is presented. It is shown that not all quasivarieties are formula-definable. Criteria are obtained for a quasivariety to be formula-definable and for a formula-definable class of models to be a quasivariety.

Alexander Piqué, Mark A. Miller, Marcus Hultmark

The wake of a horizontal-axis wind turbine was studied at a Reynolds number of $Re_D=4\times 10^6$ with the aim of revealing the effects of the tip speed ratio, $\lambda$ , on the wake. Tip speed ratios of $4\lt \lambda \lt 7$ were investigated and measurements were acquired up to 6.5 diameters downstream of the turbine. Through an investigation of the turbulent statistics, it is shown that the wake recovery was accelerated due to the higher turbulence levels associated with lower tip speed ratios. The energy spectra indicate that larger broadband turbulence levels at lower tip speed ratios contributes to a more rapidly recovering wake. Wake meandering and a coherent core structure were also studied, and it is shown that these flow features are tip speed ratio invariant, when considering their Strouhal numbers. This finding contradicts some previous studies regarding the core structure, indicating that the structure was formed by a bulk rotor geometric feature, rather than by the rotating blades. Finally, the core structure was shown to persist farther into the near wake with decreasing tip speed ratio. The structure’s lifetime is hypothesised to be related to its strength relative to the turbulence in the core, which decreases with increasing tip speed ratio.

Wolfgang Paul

The question about the existence of so-called ``hidden'' variables in quantum mechanics and the perception of the completeness of quantum mechanics are two sides of the same coin. Quantum analytical mechanics constitutes a completion of standard quantum mechanics based on the concept of stochastic trajectories in the configuration space of a quantum system. For particle systems, configuration space is made up out of their coordinates and, if relevant, their orientation. Quantum analytical mechanics derives equations of motion for these variables which allow a description of the measurement process as a dynamical physical process. After all, it is exactly these variables experiments are designed to interact with. The theory is not a replacement of Hilbert space quantum mechanics but a mathematical completion enriching our toolset for the description of quantum phenomena.

М.Ж. Тургумбаев, З.Р. Сулейменова, М.А. Мухамбетжан

In this paper, we studied the issues of integrability with the weight of the sum of series with respect to multiplicative systems, provided that the coefficients of the series are monotonic. The conditions for the weight function and the series’ coefficients are found; the sum of the series belongs to the weighted Lebesgue space Lp (1 < p < ∞). In addition, the case of p = 1 was considered. In this case, other conditions for the weighted integrability of the sum of the series under consideration are found. In the case of the generating sequence’s boundedness, the proved theorems imply an analogue of the well-known Hardy-Littlewood theorem on trigonometric series with monotone coefficients.

Oded Shor, Felix Benninger, Andrei Khrennikov

Abstract Quantum mechanics (QM) is derived based on a universe composed solely of events, for example, outcomes of observables. Such an event universe is represented by a dendrogram (a finite tree) and in the limit of infinitely many events by the p-adic tree. The trees are endowed with an ultrametric expressing hierarchical relationships between events. All events are coupled through the tree structure. Such a holistic picture of event-processes was formalized within the Dendrographic Hologram Theory (DHT). The present paper is devoted to the emergence of QM from DHT. We used the generalization of the QM-emergence scheme developed by Smolin. Following this scheme, we did not quantize events but rather the differences between them and through analytic derivation arrived at Bohmian mechanics. We remark that, although Bohmian mechanics is not the main stream approach to quantum physics, it describes adequately all quantum experiments. Previously, we were able to embed the basic elements of general relativity (GR) into DHT, and now after Smolin-like quantization of DHT, we can take a step toward quantization of GR. Finally, we remark that DHT is nonlocal in the treelike geometry, but this nonlocality refers to relational nonlocality in the space of events and not Einstein’s spatial nonlocality. By shifting from spatial nonlocality to relational we make Bohmian mechanics less exotic.

A.M. Manat, N.T. Orumbayeva

The paper investigates a non-local boundary value problem for the Benjamin-Bona-Mahony equation. This equation is a nonlinear pseudoparabolic equation of the third order with a mixed derivative. To find a solution to this problem, an algorithm for finding an approximate solution is proposed. Sufficient conditions for the feasibility and convergence of the proposed algorithm are established, as well as the existence of an isolated solution of a non-local boundary value problem for a nonlinear equation. Estimates are obtained between the exact and approximate solution of this problem.

Kangyu Weng, Aohua Cheng, Ziyang Zhang et al.

In deep learning, neural networks serve as noisy channels between input data and its latent representation. This perspective naturally relates deep learning with the pursuit of constructing channels with optimal performance in information transmission and representation. While considerable efforts are concentrated on realizing optimal channel properties during network optimization, we study a frequently overlooked possibility that neural networks can be initialized toward optimal channels. Our theory, consistent with experimental validation, identifies primary mechanics underlying this unknown possibility and suggests intrinsic connections between statistical physics and deep learning. Unlike the conventional theories that characterize neural networks applying the classic mean-field approximation, we offer analytic proof that this extensively applied simplification scheme is not appropriate in studying neural networks as information channels. To fill this gap, we develop a restricted mean-field framework applicable for characterizing the limiting behaviors of information propagation in neural networks without strong assumptions on inputs. Based on it, we propose an analytic theory to prove that mutual information maximization is realized between inputs and propagated signals when neural networks are initialized at dynamic isometry, a case where information transmits via norm-preserving mappings. These theoretical predictions are validated by experiments on real neural networks, suggesting the robustness of our theory against finite-size effects. Finally, we analyze our findings with information bottleneck theory to confirm the precise relations among dynamic isometry, mutual information maximization, and optimal channel properties in deep learning. Our work may lay a cornerstone for promoting deep learning in terms of network initialization and suggest general statistical physics mechanisms underlying diverse deep learning techniques.

Henri Gouin

Invariance theorems in analytical mechanics, such as Noether's theorem, can be adapted to continuum mechanics. For this purpose, it is useful to give a functional representation of the motion and to interpret the groups of invariance with respect to the space of reference associated with Lagrangian variables. A convenient method of calculus uses the Lie derivative. For instance, Kelvin theorems can be obtained by such a method.

Henri Gouin

The invariance theorems obtained in analytical mechanics and derived from Noether's theorems can be adapted to fluid mechanics. For this purpose, it is useful to give a functional representation of the fluid motion and to interpret the invariance group with respect to time in the quadri-dimensional reference space of Lagrangian variables. A powerful method of calculation uses Lie's derivative, and many invariance theorems and conservation laws can be obtained in fluid mechanics.

Deng Wang

Whether the first law of black hole mechanics is correct is an important question in black holes physics. Subjected to current limited gravitational wave events, we propose its weaker version that permits a relatively large perturbation to a black hole system and implement a simple test with the first event GW150914. Confronting the strain data with the theory, we obtain the constraint on the deviation parameter $α=0.07\pm0.11$, which indicates that this weaker version is valid at the 68\% confidence level. This result implies that the first law of black hole mechanics may be correct.

B.D. Koshanov, N. Kakharman, R.U. Segizbayeva et al.

The need to study boundary value problems for elliptic parabolic equations is dictated by numerous practical applications in the theoretical study of the processes of hydrodynamics, electrostatics, mechanics, heat conduction, elasticity theory and quantum physics. In this paper, we obtain two theorems on a priori estimates for solutions of nonlinear equations in a finite-dimensional Hilbert space. The work consists of four items. In the first subsection, the notation used and the statement of the main results are given. In the second subsection, the main lemmas are given. The third section is devoted to the proof of Theorem 1. In the fourth section, Theorem 2 is proved. The conditions of the theorems are such that they can be used in studying a certain class of initial-boundary value problems to obtain strong a priori estimates in the presence of weak a priori estimates. This is the meaning of these theorems.

Leonardo Colombo, Manuel de León, María Emma Eyrea Irazú et al.

A hybrid system is a system whose dynamics is given by a mixture of both continuous and discrete transitions. In particular, these systems can be utilised to describe the dynamics of a mechanical system with impacts. Based on the approach by Clark, we develop a geometric Hamilton-Jacobi theory for forced and nonholonomic hybrid dynamical systems. We state the corresponding Hamilton-Jacobi equations for these classes of systems and apply our results to analyze some examples.

James P. Finley

A generalized Euler equation of fluid dynamics is derived for describing many-body states of quantum mechanics. The Eulerian Eq. can be viewed as representing the interaction of two substates, where each substate has its own velocity and pressure fields. These field quantities are given by maps of the wavefunction. For one-body systems, the Eulerian Eq. can model either a fluid or particle description of quantum states. The generalized Euler Eq. is shown to be the gradient of an equation representing the total-energy of the two substates, having two energy fields. This total-energy Eq. is a generalization of the Bernoulli Eq. of fluid dynamics. The total-energy Eq., along with a continuity-equation, is equivalent to the time-dependent Schroedinger Eq. An equation is also derived that is equivalent to the main equation of Bohmian mechanics with additional identifications: The quantum potential of Bohmian mechanics is given as a sum of a kinetic energy and pressure fields. Also, the time derivative of the wavefunction phase is replaced by an energy field. In the formalism, field quantities are identified from their placement in equations of classical mechanics and separately, by definitions that involve the wavefunction and operators of quantum mechanics. This approach yields, unintended, and unknown energy and pressure fields. These fields, however, are shown to satisfy a continuity Eq., an equation that is equivalent to the other equation of Bohmian mechanics. It is also demonstrated that energy conservation holds for both of these energy fields, if the wavefunction is a linear-combination of eigenvectors, where the eigenvectors can be nondegenerate. A detailed investigation is given on the possible behavior, or source, of an electron that has one of the velocity fields. Alternate formulae for this velocity fields are also considered.

Q. Lu, M. Arroyo, Rui Huang

An analytic formula is derived for the elastic bending modulus of monolayer graphene based on an empirical potential for solid-state carbon atoms. Two physical origins are identified for the non-vanishing bending stiffness of the atomically thin graphene sheet, one due to the bond-angle effect and the other resulting from the bond-order term associated with the dihedral angles. The analytical prediction compares closely with ab initio energy calculations. Pure bending of graphene monolayers into cylindrical tubes is simulated by a molecular mechanics approach, showing slight nonlinearity and anisotropy in the tangent bending modulus as the bending curvature increases. An intrinsic coupling between bending and in-plane strain is noted for graphene monolayers rolled into carbon nanotubes.

Israel Gabay, Federico Paratore, Evgeniy Boyko et al.

We present a theoretical model and experimental demonstration of thin liquid film deformations due to a dielectric force distribution established by surface electrodes. We model the spatial electric field produced by a pair of parallel electrodes and use it to evaluate the stress on the liquid–air interface through Maxwell stresses. By coupling this force with the Young–Laplace equation, we obtain the deformation of the interface. To validate our theory, we design an experimental set-up which uses microfabricated electrodes to achieve spatial dielectrophoretic actuation of a thin liquid film, while providing measurements of microscale deformations through digital holographic microscopy. We characterize the deformation as a function of the electrode-pair geometry and film thickness, showing very good agreement with the model. Based on the insights from the characterization of the system, we pattern conductive lines of electrode pairs on the surface of a microfluidic chamber and demonstrate the ability to produce complex two-dimensional deformations. The films can remain in liquid form and be dynamically modulated between different configurations or polymerized to create solid structures with high surface quality.

K.A. Bekmaganbetov, K.Ye. Kervenev, Ye. Toleugazy

The theory of embedding of spaces of differentiable functions studies the important relations of differential (smoothness) properties of functions in various metrics and has a wide application in the theory of boundary value problems of mathematical physics, approximation theory, and other fields of mathematics. In this article, we prove the embedding theorems for anisotropic spaces Nikol’skii-Besov with a generalized mixed smoothness and mixed metric, and anisotropic Lorentz spaces. The proofs of the obtained results are based on the inequality of different metrics for trigonometric polynomials in Lebesgue spaces with mixed metrics and interpolation properties of the corresponding spaces.

A. Da¸sdemir

Certain product rules take various forms in the set of hypercomplex numbers. In this paper, we introduce a new multiplication form of the hypercomplex numbers that will be called «the Hadamard product», inspired by the analogous product in the real matrix space, and investigate some algebraic properties of that, including the norm of inequality. In particular, we extend our new definition and its applications to the complex matrix theory.

Petrônio A. S. Nogueira, Vincent Jaunet, Matteo Mancinelli et al.

This paper explores the screech closure mechanism for different axisymmetric modes in shock-containing jets. While many of the discontinuities in tonal frequency exhibited by screeching jets can be associated with a change in the azimuthal mode, there has to date been no explanation for the existence of multiple axisymmetric modes at different frequencies. This paper provides just such an explanation. As shown in previous works, specific wavenumbers arise from the interaction of waves in the flow with the shocks. This provides new paths for driving upstream-travelling waves that can potentially close the resonance loop. Predictions using locally parallel and spatially periodic linear stability analyses and the wavenumber spectrum of the shock-cell structure suggest that the A1 mode resonance is closed by a wave generated when the Kelvin-Helmholtz mode interacts with the leading wavenumber of the shock-cell structure. The A2 mode is closed by a wave that arises due to interaction between the Kelvin-Helmholtz wave and a secondary wavenumber peak, which arises from the spatial variation of the shock-cell wavelength. The predictions are shown to closely match experimental data, and possible justifications for the dominance of each mode are provided based on the growth rates of the absolute instability.

Nathaniel Trask, Huaiqian You, Yue Yu et al.

We present a meshfree quadrature rule for compactly supported non-local integro-differential equations (IDEs) with radial kernels. We apply this rule to develop a strong-form meshfree discretization of a peridynamic solid mechanics model that requires no background mesh. Existing discretizations of peridynamic models have been shown to exhibit a lack of asymptotic compatibility to the corresponding linearly elastic local solution. By posing the quadrature rule as an equality constrained least squares problem, we obtain asymptotically compatible convergence via reproducability constraints. Our approach naturally handles traction-free conditions, surface effects, and damage modeling for both static and dynamic problems. We demonstrate high-order convergence to the local theory by comparing to manufactured solutions and to cases with crack singularities for which an analytic solution is available. Finally, we verify the applicability of the approach to realistic problems by reproducing high-velocity impact results from the Kalthoff-Winkler experiments.