Description Of Numerical Model Research Articles

НЕСУЩАЯ СПОСОБНОСТЬ СТАЛЕЖЕЛЕЗОБЕТОННЫХ СТЕН С ЛИСТОВЫМ АРМИРОВАНИЕМ НА СТАТИЧЕСКИЕ НАГРУЗКИ

The features of the behavior of steel-plate composite walls for static loads are considered. Based on the analysis of modern technical and regulatory documentation, the rationale for the chosen research topic is given. A review of the literature is performed, and the features of development are noted. A detailed description and features of the experimental structures under study and the materials used are presented. The features of the test are considered, and the test equipment is described. Analytical and numerical calculations of structures for eccentric compression have been performed. The description of the calculation complex and the used models of materials is presented; the description of numerical models, the features of their construction and calculation are given, the results of calculations are presented – stress distributions, deformations, features of cracking. The general types of experimental eccentric compression wall models are presented, the nature of the loss of bearing capacity of experimental structures is described, and a picture of destruction is presented. The analysis of the experimental data obtained and their comparison with analytical and numerical calculations are performed.

Multi-Component MHD Model of Hot Jupiter Envelopes

A numerical model description of a hot Jupiter extended envelope based on the approximation of multi-component magnetic hydrodynamics is presented. The main attention is focused on the problem of implementing the completed MHD stellar wind model. As a result, the numerical model becomes applicable for calculating the structure of the extended envelope of hot Jupiters not only in the super-Alfvén and sub-Alfvén regimes of the stellar wind flow around and in the trans-Alfvén regime. The multi-component MHD approximation allows the consideration of changes in the chemical composition of hydrogen–helium envelopes of hot Jupiters. The results of calculations show that, in the case of a super-Alfvén flow regime, all the previously discovered types of extended gas-dynamic envelopes are realized in the new numerical model. With an increase in magnitude of the wind magnetic field, the extended envelope tends to become more closed. Under the influence of a strong magnetic field of the stellar wind, the envelope matter does not move along the ballistic trajectory but along the magnetic field lines of the wind toward the host star. This corresponds to an additional (sub-Alfvénic) envelope type of hot Jupiters, which has specific observational features. In the transient (trans-Alfvén) mode, a bow shock wave has a fragmentary nature. In the fully sub-Alfvén regime, the bow shock wave is not formed, and the flow structure is shock-less.

Experimental and numerical assessment of Light Non-Aqueous Phase Liquid (LNAPL) subsurface migration behavior in the vicinity of groundwater table

Groundwater contamination by constituents of hydrocarbon fluids may occur from the earth’s surface or subsurface. Key sources of contamination include spills and leakages from oilwells, underground storage tanks (USTs), and oil transport-tankers. These light non-aqueous phase liquid (LNAPL) contaminants pollute the soil and its continuous migration, may even end up contaminating aquifer systems. This highlights the need to understand the fate and migration behavior of LNAPL contaminants in the subsurface, especially in the unsaturated zone – with a view to limiting the contaminants transport. This study presents a numerical approach for describing and predicting the fate of LNAPL contaminant-transport in the subsurface. Multiphase flow concept was adopted, where two LNAPL phases – oil, and gas – were mainly considered. Diesel and crude oil are the hydrocarbon contaminants used, while unconsolidated sand was used as the porous matrix. Two contaminant flow scenarios were simulated experimentally — surface and subsurface imbibition. Mass balance equations and constitutive functions from the several important phenomena that influence LNAPL contaminant flow, in the subsurface, are discussed. Extended Darcy’s law in combination with van Genuchten model were applied in the 2D numerical model description for mass balance equation and constitutive relationship, respectively. The numerical simulation was executed using COMSOL Multiphysics® v. 5.5. The numerical simulation results showed a good correlation with the experimental results, and suggest that exposure time, fluid viscosity, density, contaminant supply, amount released, and the hydraulic properties of the porous matrix, are the most important parameters in LNAPL contaminant subsurface migration. This study thereby concludes that if the fluid thermodynamic properties and the hydraulic properties of the porous matrix are known, the numerical model can accurately predict the migration behavior of hydrocarbon contaminants. In that way, it becomes possible to effectively track oil-spills and leakages propagating into the vicinity of groundwater table and freshwater aquifer. The study outcome is useful in designing and implementing efficient hydrocarbon contamination remediation approaches and saving time by taking the right action.

Methоd of rigging parameters calculation for midwater trawls

The rigging parameters calculation for midwater trawls are discussed with description of numerical model for calculating the parameters of trawl boards, hydrodynamic kites, and dispersed and concentrated weights which provide the designed values of horizontal and vertical opening of the trawl mouth. A distinctive feature of the proposed technique is a systematic approach: the trawl, trawl boards, and wires are considered as a joint complex.

Asymptotics for Optimal Design Problems for the Schrödinger Equation with a Potential

We study the problem of optimal observability and prove time asymptotic observability estimates for the Schrödinger equation with a potential in L∞Ω, with Ω⊂Rd, using spectral theory. An elegant way to model the problem using a time asymptotic observability constant is presented. For certain small potentials, we demonstrate the existence of a nonzero asymptotic observability constant under given conditions and describe its explicit properties and optimal values. Moreover, we give a precise description of numerical models to analyze the properties of important examples of potentials wells, including that of the modified harmonic oscillator.

The major influence of the conduction-band-offset on Zn(O, S)/CuIn0.7Ga0.3Se2 solar cells

Conversion efficiencies greater than 19% for thin-film solar cells based on (CIGS) cells with CdS buffer layers prepared by different methods are reported by several groups in recent years (Ramanathan et al., 2003, Contreras et al., 2005). However, the toxicity of cadmium leads the research community to replace the CdS buffer layer with another alternative while preserving the performance already achieved in different laboratories. Our work is focused on this type of CIGS based solar cells with Zn(O, S) as a buffer layer in place of CdS to avoid the toxic effect of cadmium. In this study, we simulated this kind of CIGS thin-film solar cell with the variation of Zn(O, S) affinity until an optimal interval which corresponds to the best efficiency of 20.63% where the affinity of CIGS remains constant. Its optimal value is around 4.58 eV for a (gallium/indium) ratio of 0.3 eV corresponds to a band gap energy of 1.17 eV as it is already demonstrated by several groups (Repins et al., 2008, Powalla et al., 2009) and the resulting Conduction Band Offsets (CBO) between CIGS and Zn(O, S) can range from −0.2 to +1.2 eV if the full range of the (oxygen/sulfur) ratio is considered from the pure ZnO to the pure ZnS. The simulation tool used for this study is Atlas of Silvaco-package based on the digital resolution 2D transport equations governing the conduction mechanisms in semiconductor devices as described in Section “Atlas numerical model description”. The J-V characteristics are simulated under standard AM1.5G Illumination.

The thermal structure of volcanic passive margins

Over the past ten years we have numerically modelled the properties of the magmatism generated at four of the key areas where the ‘mantle plume–volcanic margin hypothesis’ is expected to be valid: the North Atlantic, South Atlantic, India–Seychelles and Afar. Our model incorporates many of the original assumptions in the classic White and McKenzie model, with pure shear of the lithospheric mantle, passive upwelling and decompressional melting. Our model is however two- rather than one-dimensional, can capture the rift history (extension rate changes and axis jumps) and tracks mantle depletion during melting. In all four of our study areas we require the sub-lithospheric mantle to be 100 – 200°C hotter than ‘normal’, non-volcanic margins to explain the characteristics of the magmatism. In the three passive margin cases we find this excess temperature is limited to a 50 – 100 km thick layer. We require this layer temperature to drop along-strike away from the proposed sites of plume impact at the base of the lithosphere. However, we also find that lithospheric thickness and rift history are as important as temperature for controlling the magmatism. Our work therefore lends support to the hypothesis that the excess magmatism at volcanic margins is due to a thermal anomaly in the asthenosphere, albeit with consideration of extra parameters. Supplementary material: Numerical model description is available at https://doi.org/10.6084/m9.figshare.c.3924505

Numerical Model Description of Fibres Winding Process for New Technology of Winding Fibres on the Frames

Currently, traditional materials are very often replaced by composite materials in many industrial areas. The advantages of these materials consist mainly in their lightweight, high strength and flexibility, corrosion resistance and a long lifespan. The use of composites reaches its large development in the field of aerospace. This article discusses quality of the manufacturing process technology of a specially shaped composite frame in 3D space. The used technology is based on a winding of carbon, glass, organic filament rovings on a polyurethane core. Polyurethane core which is a geometry of frame with and without a circular cross section. Quality production of said type of composite frame depends primarily on the correct winding of fibers on a polyurethane core. It is especially needed to ensure the correct angles of the fibers winding on the polyurethane core and the homogeneity of individual winding layers. The quality of fibers winding also depends on the material properties of polyurethane core and fibers. The article describes mathematical model for use an industrial robot in filament winding and how to calculate the trajectory of the robot. When winding fibers on the polyurethane core which is fastened to the robot-end-effector so that during the winding process goes through a fibre-processing head on the basis of the suitably determined robot-end-effector trajectory. We use for description numerical model and matrix calculus to enumerate the trajectory of the robot-end-effector to determine the desired passage of the frame through the fibre-processing head. The calculation of the trajectory was programmed in the Delphi development environment. Equations and relations of the numerical model are important for use a real solving of the passage of a polyurethane core through fibre-processing head.

Numerical prediction of thermo-aeraulic behavior for a cavity with internal linear heat source

Computational Fluid Dynamics (CFD) is a promising way, nowadays, to predict the air Flow in enclosures. As a result, the objective of this study is to assess the potential of CFD technique to predict the air Flows driven by buoyancy in heated real-scale rooms. The numerical model is validated using experimental data for fullscale test rooms; therefore, the experimental set-up is rst presented. This is followed by the numerical model description, focusing on its principal elements: computational domain geometry, discretization, turbulence model, radiation model, and thermal boundary conditions. In addition, a simpli ed approach is proposed to integrate a heat source in CFD models: Term source homogeneously spread all over the volume of the heat source. Comprehensive experimental-numerical comparisons are presented in terms of heat transfer to the walls of the test room, heat source behavior, and plume development. The results show that the model developed in this study leads to realistic predictions. Finally, the simpli ed CFD description of heat sources developed here can be extrapolated for other con gurations - di erent power, heat emission (convection/radiation), dimensions, and shape. Consequently, this method can be applied in detailed studies dealing with thermal comfort, indoor air quality, and energy consumption for heated rooms.

The geochemical fingerprint of microbial long-distance electron transport in the seafloor

Recently, a novel “electrogenic” type of sulfur oxidation has been documented in marine sediments, whereby long filamentous cable bacteria are generating electrical currents over centimeter-scale distances. Here we propose a numerical model description that is capable of quantitatively simulating the solute depth profiles and biogeochemical transformations in such electro-active marine sediments. The model is based on a conventional reactive transport description of marine sediments, which is extended with a new model formulation for the long-distance electron transport induced by the cable bacteria. The mechanism of electron hopping is implemented to describe the electron transport along the longitudinal axis of the microbial filaments. We demonstrate that this model is capable of reproducing the observed geochemical fingerprint of electrogenic sulfur oxidation, which consists of a characteristic set of O2, pH and H2S depth profiles. Our simulation results suggest that the cable bacteria must have a high affinity for both oxygen and sulfide, and that intensive cryptic sulfur cycling takes place within the suboxic zone. A sensitivity analysis shows how electrogenic sulfur oxidation strongly impacts the biogeochemical cycling of sulfur, iron, carbon and calcium in marine sediments.

A systematic approach for model verification: application on seven published activated sludge models

The quality of simulation results can be significantly affected by errors in the published model (typing, inconsistencies, gaps or conceptual errors) and/or in the underlying numerical model description. Seven of the most commonly used activated sludge models have been investigated to point out the typing errors, inconsistencies and gaps in the model publications: ASM1; ASM2d; ASM3; ASM3 + Bio-P; ASM2d + TUD; New General; UCTPHO+. A systematic approach to verify models by tracking typing errors and inconsistencies in model development and software implementation is proposed. Then, stoichiometry and kinetic rate expressions are checked for each model and the errors found are reported in detail. An attached spreadsheet (see http://www.iwaponline.com/wst/06104/0898.pdf) provides corrected matrices with the calculations of all stoichiometric coefficients for the discussed biokinetic models and gives an example of proper continuity checks.

A model for the evaluation of long-term airborne pollution transport at regional and continental scales

The paper contains the description of numerical model of the airborne pollution transport developed by a scientific team of M. Galperin. During several years the model was used for the calculations in Meteorological Synthesizing Centre – East, within the scope of Co-operational Programme for Monitoring and Evaluation of the Long-Range Transmission of air Pollutants in Europe (EMEP). The paper presents the extensive description of the current version of the model and outlines the results of its quality assurance. The model is based on an original Eulerian advection scheme with variable time step, which can be classified as a “pseudo-Lagrangian” scheme. Vertical concentration profiles are parameterized by truncated Gaussian function with dynamic parameters calculated at every model time step. The model includes two types of chemistry and deposition units: acid compounds and ammonia, and heavy metals carried with aerosol particles. One of the model advantages is the ability to make the evaluation of source–receptor pollution exchange for substances with non-linear atmospheric chemistry and deposition. The model evaluation was carried out by the comparison of multi-annual calculated concentrations with measured values for several acidifying substances.

98/02388 Analysis of chemical heat pumps (CHPS): Basic concepts and numerical model description : Mbaye, M. et al. Appl. Therm. Eng., 1998 (Pub. 1997), 18, (3–4), 131–146

98/02388 Analysis of chemical heat pumps (CHPS): Basic concepts and numerical model description : Mbaye, M. et al. Appl. Therm. Eng., 1998 (Pub. 1997), 18, (3–4), 131–146

Analysis of chemical heat pumps (CHPs): Basic concepts and numerical model description

Thermochemical phenomena occurring during the reaction between a gas and solid porous media (thermochemical materials) have been modelled. The practical application envisaged is the use of these thermochemical materials in chemical heat pumps (CHP) to produce both heat and cold. In the synthesis part of the cycle, a gas (e.g. ammonia) at a moderate pressure reacts uniformly with the salt (e.g. MnCl 2·2NH 3) component of a thermochemical material. Subsequently the ammoniated salt (MnCl 2·6NH 3) is decomposed to release the gas at an elevated pressure. A detailed numerical model is presented for the decomposition phase of the CHP reaction cycle. The numerical simulation of a CHP reactor during a synthesis decomposition reaction cycle has several specific requirements. The phase change problem involving discontinuities in the thermal properties of the two different salts at their reaction interface needs special care for numerical solution. In this paper, the source-based method which is a fixed grid enthalpy approach, was used. The solution of the partial differential equation was obtained, using a control volume approach around each spacial node. This thermal study examined configurations that had different reactor diameters, and other parameters that influenced heat transfer. Typical results included conversions, power generated as a function of reactor diameter and time-on-stream, required heat exchange area, and heat losses.

Analysis of Catalytically Enhanced Solar Absorption Chemical Reactors: Part I—Basic Concepts and Numerical Model Description

A detailed numerical model is presented for high-temperature, catalytically enhanced, solar absorption chemical reactors. In these reactors, concentrated solar energy is volumetrically absorbed throughout a porous absorber matrix impregnated with a catalyst. The catalyst promotes heterogeneous reactions with fluid-phase reactant species flowing through the absorber. This paper presents a description of a numerical model and the basic concepts of reactor operation. The numerical model of the absorber includes solar and infrared radiation, heterogeneous chemical reactions, conduction in the solid phase, and convection between the fluid and solid phases. The model is nonlinear primarily due to both the radiative transfer and the heterogeneous chemistry occurring in the absorber. The nonlinear two-point boundary value problem is solved using superposition with orthonormalization and an adaptive solution point scheme. This technique preserves accuracy throughout the domain. The model can be modified for other chemical reactions and can be simplified to model volumetric air-heating receivers.