TECHNICAL NOTE | doi:10.20944/preprints202003.0337.v1
Subject: Mathematics & Computer Science, Artificial Intelligence & Robotics Keywords: Restricted Boltzmann machines; artificial intelligence; deep learning
Online: 23 March 2020 (05:51:32 CET)
Restricted Boltzmann machines (RBMs) are the building blocks of some deep learning networks. However, despite their importance, it is our perception that some very important derivations about the RBM are missing in the literature, and a beginner may feel RBM very hard to understand. We provide here these missing derivations. We cover the classic Bernoulli-Bernoulli RBM and the Gaussian-Bernoulli RBM, but leave out the ``continuous'' RBM as it is believed not as mature as the former two. This tutorial can be used as a companion or complement to the famous RBM paper ``Training restricted Boltzmann machines: An introduction'' by Fisher and Igel.
ARTICLE | doi:10.20944/preprints201804.0074.v1
Subject: Mathematics & Computer Science, Other Keywords: energy; KNL; MCDRAM; memory; Lattice Boltzmann; HPC; DVFS
Online: 6 April 2018 (10:46:23 CEST)
Energy consumption of processors and memories is quickly becoming a limiting factor in the deployment of large computing systems. For this reason it is important to understand the energy performance of these processors and to study strategies allowing to use them in the most efficient way. In this work we focus on computing and energy performance of the Knights Landing Xeon Phi, the latest Intel many-core architecture processor for HPC applications. We consider the 64-core Xeon Phi 7230, and profile its performance and energy efficiency using both its on-chip MCDRAM and the off-chip DDR4 memory as the main storage for application data. As a benchmark application we use a Lattice Boltzmann code heavily optimized for this architecture, and implemented using several different arrangements of the application data in memory (data-layouts, in short). We also assess the dependence of energy consumption on data-layouts, memory configurations (DDR4 or MCDRAM), and number of threads per core. We finally consider possible trade-offs between computing performance and energy efficiency, tuning the clock frequency of the processor using the Dynamic Voltage and Frequency Scaling (DVFS) technique.
ARTICLE | doi:10.20944/preprints201907.0087.v1
Subject: Chemistry, Chemical Engineering Keywords: pinning-depinning; evaporation; chemically stripe-patterned surfaces; lattice Boltzmann
Online: 5 July 2019 (04:40:38 CEST)
The liquid-vapor phase change lattice Boltzmann method is used to investigate the pinning-depinning mechanism of the contact line during droplet evaporation on the stripe-patterned surfaces in 3D space. Considering the curvature of the contact line and the direction of the unbalanced Young’s force, the local force balance theory near the stripe boundary is proposed to explain the steady state of the droplets on the stripe-patterned surfaces. An equation is proposed to evaluate the characteristic contact angle of the stabilized droplets. During the evaporation of the droplet, the stick-slip-jump behavior and the CCR-Mixed-CCA mode can be well captured by the lattice Boltzmann simulation. When the contact line is pinned to the stripe boundary, the contact line in the direction perpendicular to the stripes is slowly moving while the curvature of the contact line is gradually increasing. The gradually increasing curvature of the contact line accelerates the movement of the contact line, and the final contact line is detached from the stripe boundary. The research results provide theoretical support and guidance for the design, improvement and application of patterned surfaces in the field of micro-fluidic and evaporation heat transfer.
ARTICLE | doi:10.20944/preprints202007.0188.v1
Subject: Mathematics & Computer Science, Applied Mathematics Keywords: plasmas; fluid mechanics; compressible flow; statistical mechanics theorems; irreversible thermodynamics; Maxwell-Boltzmann distribution; electron gas; magnetic fields; laws of thermodynamics; viscosity; boltzmann kinetic equation
Online: 9 July 2020 (12:16:25 CEST)
In this study, we mainly focus on the behavior of an electron gas produced by argon plasma that is bounded by a moving rigid flat plate. The effects of an external magnetic field on the electrons collected with each other, with positive ions, and with neutral atoms in the plasma fluid are investigated. We used the BGK model of the Boltzmann kinetic equation, which is fundamental in the study of the gas dynamics from the continuum flow to the free-molecular regimes with Maxwellian velocity distribution functions of the various species. An exact analytical solution of the model equations for the unsteady flow is given using the moment and the traveling wave methods. The behavior of the mean velocity of electrons is illustrated, which compatible with the variation of the shear stress, viscosity coefficient, and the initial and boundary conditions. Besides, the thermodynamic prediction is investigated by applying the principles of irreversible thermodynamics and Gibbs formula. It is found that the thermodynamic variables verify the Boltzmann’s H–theorem, the principle of Le Chatelier, and the Thermodynamics Second Law for the non-equilibrium processes of the system. Qualitative agreements with previous related papers are introducing. 3-Dimensional graphics for the calculating variables are offering, and their behavior is deeply discussed.
ARTICLE | doi:10.20944/preprints201710.0043.v1
Subject: Materials Science, Surfaces, Coatings & Films Keywords: BaxSr1-xTiO3 films; boltzmann modelling; optical band gap; deposition rate; stoichiometric content
Online: 9 October 2017 (05:20:59 CEST)
Thin films (100-400 nm) of BaxSr1-xTiO3 (0≤x≤1) deposited in RF-magnetron co-sputtering equipment are presented in this research work. The change of deposition rate, gap energy, and resistivity as a function of temperature- applied power change in the growth parameters was studied through the ISO colour-code lines constructed with MATLAB: By analysing the trend information and take into account the influence of the calculated "x" parameter with the Boltzmann profile fitting is proposed a method to allow a controlled set up of the RF-magnetron co-sputtering system and predict the Eg and resistivity values in the BaxSr1-xTiO3 solid solution with 0≤x≤1 for amorphous and crystalline phases. Also, a versatile tool to optimise the deposition process and material properties.
ARTICLE | doi:10.20944/preprints202203.0371.v2
Subject: Physical Sciences, General & Theoretical Physics Keywords: Entropy; Boltzmann principle; Planck’s law; Dynamical system; Von Koch’s inequality; Riemann Hypothesis; abc conjecture
Online: 7 June 2022 (04:14:37 CEST)
In this paper, we propose the expansion of the Planck distribution functions which is derived from the Boltzmann principle. Furthermore, we examine to expand Planck's law using new distribution functions. Moreover, using the ideas applied to the expansion of the Planck distribution function, we show that the derivation of Von Koch's inequality without using the Riemann Hypothesis and the negative consequence of the abc conjecture. Besides, we describe some issues for the future. Namely, we discuss that the Entropy is associated with the dynamical system, and the classical gravity theory of Newton's law and the electromagnetism of Coulomb's law by the law of inverse squares.
ARTICLE | doi:10.20944/preprints202205.0366.v1
Subject: Physical Sciences, Condensed Matter Physics Keywords: Electron-phonon coupling; Nanoparticle; Ultrathin layer; Nonthermal melting; Tight-binding molecular dynamics; Boltzmann collision integrals; XTANT
Online: 26 May 2022 (10:44:54 CEST)
Laser irradiation of metals is widely used in research and applications. In this work, we study how the material geometry affects electron-phonon coupling in nano-sized gold samples: an ultrathin layer, nano-rod, and two types of gold nanoparticles: cubic and octahedral. We use the combined tight-binding molecular dynamics Boltzmann collision integral method implemented within XTANT-3 code to evaluate the coupling parameter in irradiation targets at high electronic temperatures (up to Te~20,000 K). Our results show that the electron-phonon coupling in all objects with the same fcc atomic structure (bulk, layer, rod, cubic and octahedral nanoparticles) is nearly identical at electronic temperatures above Te~7000 K, independently of geometry and dimensionality. At low electronic temperatures, reducing dimensionality reduces the coupling parameter. Additionally, nano-objects under ultrafast energy deposition experience nonthermal damage due to expansion caused by electronic pressure, in contrast to bulk metal. Nano-object ultrafast expansion leads to ablation/emission of atoms, and disorder inside of the remaining parts. These nonthermal atomic expansion and melting are significantly faster than electron-phonon coupling, forming a dominant effect in nano-sized gold.
ARTICLE | doi:10.20944/preprints201905.0369.v1
Subject: Engineering, Mechanical Engineering Keywords: lattice Boltzmann method; mass-conserved wall treatment; non-equilibrium extrapolation boundary condition; mass leakage; parallel computation; CFD
Online: 30 May 2019 (13:38:44 CEST)
In this study, the multi-relaxation-time lattice Boltzmann method is applied to investigate the oscillatory instability of lid-driven flows in two-dimensional semi-elliptical cavities with different vertical to horizontal aspect ratios K in the range of 1.0--3.0. The program implemented in this study is parallelized using CUDA (compute unified device architecture), a parallel computing platform, and computations are carried out on NVIDIA Tesla K40c GPU. To carry out precise calculations, the CUDA algorithm is extensively investigated, and its parallel efficiency indicates that the maximum speedup is 47.6 times faster. Furthermore, the steady--oscillatory Reynolds numbers are predicted by implementing the CUDA-based programs. The amplitude coefficient is defined to quantify the time-dependent oscillation of the velocity magnitude at the monitoring point. The simulation results indicate that the transition Reynolds numbers correlate negatively with the aspect ratio of the semi-elliptical cavity, and are smaller than those of the rectangular cavity at the same aspect ratio. In addition, the detailed vortex structures of the semi-elliptical cavity within a single period are also investigated when the Reynolds number is larger than the steady--oscillatory value to determine the effects of periodic oscillation of the velocity magnitude.
ARTICLE | doi:10.20944/preprints202208.0384.v1
Subject: Physical Sciences, General & Theoretical Physics Keywords: De Sitter-Planck background; sub-Planckian bubbles; quantum-Boltzmann statistics; generalized uncertainty relations; Quantum Black Holes; cosmological wormholes.
Online: 22 August 2022 (11:53:37 CEST)
– Every physical theory involving quantum fields does require a model of the quantum vacuum. The vacuum associated to quantum gravity must incorporate the prescriptions from both the theory of relativity and quantum physics. In this work, starting from the hypothesis of nucleation of sub-Planckian bubbles from a de Sitter vacuum, we study the necessary conditions to obtain baby universes, black holes and particles. The de Sitter-Planck background is described by an “infinite” Quantum Boltzmann statistics that generates fermions and bosons, and manifests itself as a deformation of the geometry that leads to a generalized uncertainty principle and a unified expression for the generalized Compton wavelength and event horizon size, drawing a connection between quantum black holes and elementary particles, the latter seen as a collective organization of the bubbles of the vacuum described by the generalized Compton wavelength. The quantum thermodynamics of black holes is then outlined and the physical history of each bubble is found to depend on the cosmological constant described in terms of thermodynamic pressure. Finally, a suggestive treatment of the Casimir effect is provided in the de Sitter-Planck background with Quantum-Boltzmann statistics and wormholes are explored as bubble coalescence processes.
ARTICLE | doi:10.20944/preprints201807.0139.v1
Subject: Physical Sciences, General & Theoretical Physics Keywords: foundations of thermodynamics; Boltzmann vs. Carnot; engineering thermodynamics; quantum thermodynamics; Principle of Least Action; complementarity; Maupertuis; Lazare Carnot
Online: 9 July 2018 (13:07:30 CEST)
Currently, there are two approaches to the foundations of thermodynamics. One, associated with the mechanistical Clausius-Boltzmann tradition, is favored by the physics community. The other, associated with the post-mechanical Carnot tradition, is favored by the engineering community. The bold hypothesis is that the conceptual foundation of engineering thermodynamics is the more comprehensive. Therefore, contrary to the dominant consensus, engineering thermodynamics (ET) represents the true foundation of thermodynamics. The foundational issue is crucial to a number of unresolved current and historical issues in thermodynamic theory and practice. ET formally explains the limited successes of the ‘rational mechanical’ approaches as idealizing special cases. Thermodynamic phenomena are uniquely dissymmetric and can never be completely understood in terms of symmetry-based mechanical concepts. Consequently, ET understands thermodynamic phenomena in new way, in terms of the post-mechanical formulation of action. The ET concept of action and the action framework trace back to Maupertuis’s Principle of Least Action, both clarified in the engineering worldview research program of Lazare and Sadi Carnot. Despite the intervening Lagrangian ‘mechanical idealization of action’, the original dualistic, indeterminate engineering understanding of action, somewhat unexpectedly, re-emerged in Planck’s quantum of action. The link between engineering thermodynamics and quantum theory is not spurious and each of our current formulations helps us develop our understanding of the other. Both the ET and quantum theory understandings of thermodynamic phenomena, as essentially dissymmetric (viz. embracing complementary), entail that there must be an irreducible, cumulative historical, qualitatively emergent, aspect of reality.
ARTICLE | doi:10.20944/preprints202005.0444.v1
Subject: Mathematics & Computer Science, Computational Mathematics Keywords: restricted Boltzmann machine; contrastive divergence; extreme learning machine; online sequential extreme learning machine; autoencoders; deep belief network; deep learning
Online: 27 May 2020 (08:18:39 CEST)
Abstract: The main contribution of this paper is to introduce a new iterative training algorithm for restricted Boltzmann machines. The proposed learning path is inspired from online sequential extreme learning machine one of extreme learning machine variants which deals with time accumulated sequences of data with fixed or varied sizes. Recursive least squares rules are integrated for weights adaptation to avoid learning rate tuning and local minimum issues. The proposed approach is compared to one of the well known training algorithms for Boltzmann machines named “contrastive divergence”, in term of time, accuracy and algorithmic complexity under the same conditions. Results strongly encourage the new given rules during data reconstruction.
REVIEW | doi:10.20944/preprints202009.0256.v1
Subject: Chemistry, Physical Chemistry Keywords: attractive and repulsive forces; Debye’s screening length (1/k); Poisson-Boltzmann (PB) equation; food colloids; coagulation; stabilizers; lipids; polymers; electrolytes
Online: 11 September 2020 (10:05:50 CEST)
Different forces play a key-role in the stability of food colloid dispersions. Focus is here on those controlling attraction and/or repulsion, which concur to stabilization, phase separation, coagulation, and are quite evident in water-based systems. Combination of attractive and repulsive forces favors, or hinders, the association of colloid entities; such processes are often met in food technology. The above processes depend on the forces at work, and on colloid concentration in the medium (i.e. on inter-particle distance). Worked examples deals with milk manipulation procedures, ending in cheese formation. The whole milk-working sequence is controlled by the combination of forces leading to aggregation and phase separation of casein and other milk components. Thereafter, one gets either fresh, for prompt consumption, or aged cheeses. The combination of attractive (van der Waals, vdW, and depletion) with repulsive (double layer, DL, but also with steric) forces results in the dominance of aggregation versus dispersion modes in all steps of milk transformation, which depend on the distance among colloid particles, on the amplitude of the mentioned forces, and on their decay length. The combined role of double layer and van der Waals (vdW) forces is at the basis of the DLVO theory on colloid stability, which is properly modified when these forces overlap with steric stabilization and, eventually, with depletion. Steric effects are dispersive, depletion ones favor colloid nucleation in a single phase. The milk manipulation chain is a worked example of the intriguing association features controlled by the mentioned forces (and of ancillary ones, as well), and indicates which forces favor the formation of products such as Parmesan or Mozzarella cheese, but are not alien to the preparation of many other dairy products.
ARTICLE | doi:10.20944/preprints201905.0050.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: oxygen delivery; optimization; mass transfer; transport; bone tissue engineering; computational fluid dynamics; lattice Boltzmann method; scaffold design; culturing protocol; Lagrangian scalar tracking
Online: 6 May 2019 (10:37:06 CEST)
Tissue engineering has the potential for repairing large bone defects, which impose a heavy financial burden on the public health. However, difficulties with O2 delivery to the cells residing in the interior of tissue engineering scaffolds make it challenging to grow artificial tissues of clinically-relevant sizes. This study uses image-based simulation in order to provide insight into how to better optimize the scaffold manufacturing parameters, and the culturing conditions, in order to resolve the O2 bottleneck. To do this, high resolution 3D X-ray images of two common scaffold types (salt leached foam and non-woven fiber mesh) are fed into a Lattice Boltzmann Method fluid dynamics and reactive Lagrangian Scalar Tracking mass transfer solvers. The obtained findings indicate that the scaffolds should have maximal surface area-to-solid volume ratios, for higher chances of the molecular collisions with the cells. Furthermore, the cell culture media should be flown through the scaffold pores as fast as practically possible (without detaching or killing the cells). Finally, we have provided a parametric sweep that maps how the molecular transport within the scaffolds is affected by variations in rates of O2 consumption by the cells. Ultimately, the results of this study are expected to benefit the computer-assisted design of tissue engineering scaffolds and culturing experiments.
ARTICLE | doi:10.20944/preprints201907.0314.v1
Subject: Physical Sciences, Mathematical Physics Keywords: entropy; Boltzmann statistics; Lorentz-factor; mereology; analytical philosophy; conservation laws; vacuum energy; cosmologic constant problem; invariance; hypercomplex numbers; Octonions; energy-mass equivalence; Ur-Alternatives; mereotopology; mereophysics
Online: 28 July 2019 (14:39:59 CEST)
Mereology stands for the philosophical concept of parthood and is based on a sound set of fundamental axioms and relations. One of these axioms relates to the existence of a universe as a thing having part all other things. The present article formulates this logical expression first as an algebraic inequality and eventually as an algebraic equation reading in words: The universe equals the sum of all things. “All things” here are quantified by a “number of things”. Eventually this algebraic equation is normalized leading to an expression The whole equals the sum of all fractions. This introduces “1” or “100%” as a quantitative – numerical - value describing the “whole”. The resulting “basic equation” can then be subjected to a number of algebraic operations. Especially squaring this equation leads to correlation terms between the things implying that the whole is more than just the sum of its parts. Multiplying the basic equation (or its square) by a scalar allows for the derivation of physics equations like the entropy equation, the ideal gas equation, an equation for the Lorentz-Factor, conservation laws for mass and energy, the energy-mass equivalence, the Boltzmann statistics, and the energy levels in a Hydrogen atom. It further allows deriving a “contrast equation” which may form the basis for the definition of a length and a time scale. Multiplying the basic equation with vectors, pseudovectors, pseudoscalars and eventually hypercomplex numbers opens up the realm of possibilities to generate many further equations.
ARTICLE | doi:10.20944/preprints202007.0565.v1
Subject: Mathematics & Computer Science, Applied Mathematics Keywords: Unsteady Exact analytical solutions; Partial differential equations system; Travelling wave method; Moment method; Boltzmann kinetic equation; Neutral non-homogenous gas; Thermal radiation force; Non-equilibrium irreversible thermodynamics; Internal energy.
Online: 23 July 2020 (12:53:22 CEST)
In the present paper, the effect of the non-linear thermal radiation on the neutral gas mixture in the unsteady state is investigated for the first time. The unsteady BGK technique of the Boltzmann kinetic equations for a neutral non-homogenous gas is solved. The solution of the unsteady case makes the problem more general significance than the stationary one. For this purpose, the moments' method, together with the traveling wave method, is applied. The temperature and concentration are calculated for each gas component and mixture for the first time.Furthermore, the study is held for aboard range of temperatures ratio parameter and a wide range of the molar fraction. The distribution functions are calculated for each gas component and the gas mixture. The significant non-equilibrium irreversible thermodynamic characteristics the entire system is acquired analytically. That technic allows us to investigate the consistency of Boltzmann's H-theorem, Le Chatelier principle, and thermodynamics laws. Moreover, the ratios among the different participation of the internal energy alteration are evaluated via the Gibbs formula of total energy. The final results are utilized to the argon-helium non-homogenous gas at different magnitudes of radiation force strength and molar fraction parameters. 3D-graphics are presented to predict the behavior of the calculated variables, and the obtained results are theoretically discussed.