Verification Of Calculations Research Articles

Ефективність суднових енергетичних установок з теплообмінними апаратами з трубних пучків з лунковими системами

The direction of increasing the efficiency of marine power plants by using heat exchange elements that implement intensive methods of heat transfer, which are characterized by a predominant increase in heat transfer over aerodynamic resistance, is considered. The research method is mathematical modeling of processes in power plants at the level of their individual elements – heat engine, power, and technological heat exchangers. The adequacy of the mathematical model for research the efficiency of power plants is justified by the results of verification and validation by comparing the results of calculations with the results of a physical experiment that have a discrepancy not exceeding 9.3 %. The goal of the research is to improve the economic, environmental, resource and weight-size parameters of power plants by using heat exchange elements with the intensification of the processes of convective transfer of heat and mass by using finned surfaces with dimples. Thanks to the performance of dimple systems on the edges of round pipes with spiral-ribbon finning and elliptical pipes with lamellar finning, it is possible to increase the heat transfer coefficient up to 36 %, while the resistance coefficient of the beam remains unchanged. The use of heat exchangers with the proposed heat transfer elements as part of ship power plants with low-speed engines and gas-and-steam turbine units allows to improve their economic and environmental characteristics. It was obtained that for tankers of the PANAMAX type, the increase in the efficiency of the ship's power plant is 1.3 % due to the use of elliptical surfaces with plate finning and hole systems on the ribs in the utilization boiler. The ship's EEDI index decreased by 1.7 %. For container ships with a deadweight of more than 100,000 tons, the change in these indexes was 2.5 and 2.7 %, respectively. For a marine gas-and-steam turbine plant, the efficiency increase was 2.4 %. The presented mathematical model of the power plant is characterized by positive results of approbation for constructive and verification calculations of power plants in marine energy, transport, and industry.

Recommendations for finite element modelling of nickel-titanium stents-Verification and validation activities.

The objective of this study is to present a credibility assessment of finite element modelling of self-expanding nickel-titanium (Ni-Ti) stents through verification and validation (VV) activities, as set out in the ASME VV-40 standard. As part of the study, the role of calculation verification, model input sensitivity, and model validation is examined across three different application contexts (radial compression, stent deployment in a vessel, fatigue estimation). A commercially available self-expanding Ni-Ti stent was modelled, and calculation verification activities addressed the effects of mesh density, element integration and stable time increment on different quantities of interests, for each context of use considered. Sensitivity analysis of the geometrical and material input parameters and validation of deployment configuration with in vitro comparators were investigated. Results showed similar trends for global and local outputs across the contexts of use in response to the selection of discretization parameters, although with varying sensitivities. Mesh discretisation showed substantial variability for less than 4 × 4 element density across the strut cross-section in radial compression and deployment cases, while a finer grid was deemed necessary in fatigue estimation for reliable predictions of strain/stress. Element formulation also led to substantial variation depending on the chosen integration options. Furthermore, for explicit analyses, model results were highly sensitive to the chosen target time increment (e.g., mass scaling parameters), irrespective of whether quasistatic conditions were ensured (ratios of kinetic and internal energies below 5%). The higher variability was found for fatigue life simulation, with the estimation of fatigue safety factor varying up to an order of magnitude depending on the selection of discretization parameters. Model input sensitivity analysis highlighted that the predictions of outputs such as radial force and stresses showed relatively low sensitivity to Ni-Ti material parameters, which suggests that the calibration approaches used in the literature to date appear reasonable, but a higher sensitivity to stent geometry, namely strut thickness and width, was found. In contrast, the prediction of vessel diameter following deployment was least sensitive to numerical parameters, and its validation with in vitro comparators offered a simple and accurate (error ~ 1-2%) method when predicting diameter gain, and lumen area, provided that the material of the vessel is appropriately characterized and modelled.

Method of thermal calculation of the locomotive traction engine armature

A verification calculation of traction engines of locomotives is proposed, taking into account the temperature mode. Analytical expressions for the static thermal state of the engine are obtained, reflecting the balance of heat release and heat removal powers. Keywords: locomotive, engine, armature, reliability, electric drive, heating, operation, heat flow, mathematical model. lam75@mail.ru, glazunovdm@yandex.ru, ats@rgups.ru

Multi-physics core analysis and verification of NuScale reactor with coupling PARCS/RELAP

The attractiveness of small modular reactors (SMR) lies in high safety, simplicity of design, reduced siting costs, etc.The NuScale is considered one of the unique SMR reactors due to design advantages such as the immersion of the containment vessel in the reactor pool, natural circulation cooling mechanism, integrated loop, and flexibility of its safety functions for up to 72 h after severe accidents. Investigating the neutronic and thermal–hydraulic parameters of a reactor is one of the concerns of nuclear-reactor designers because such parameters play an essential role in the design process and safety assessment. Therefore, in the present study, the internal coupling capability of the PARCS and RELAP codes has been used to analyze the multi-physics parameters of the core and loop of the NuScale reactor. The DRAGON5 code was used to perform lattice calculations and prepare the PMAXS library for PARCS. The code-by-code verification of lattice and core calculations was carried out by the MCNP code. Multiplication factor, power distribution, fuel and moderator feedback coefficients, and other thermal–hydraulic parameters were calculated under a steady-state condition. Burnup calculations have also been performed to investigate the fuel cycle parameters. The results show an acceptable accuracy in comparison with the NuScale reported data.

Retrospective Analysis of Treatment Time Calculation Agreement Between TPS and Manual Method and Source Strength Verification for 13 HDR Ir-192 Sources In Flexitron Brachytherapy Unit: A Single Institute Experience

Introduction: Source strength measurement and verification during every source exchange in high dose rate (HDR) Brachytherapy 192Ir is primary part of quality assurance program as recommended by national regulatory body Atomic Energy Regulatory Board, Mumbai, India. The purpose of this study was to evaluate RAKR (in-house measurement) of 192Ir using re-entrant well-type ionization chamber with stated RAKR values as provided by the manufacturer in source certificate and to check the accuracy of the Oncentra treatment planning system calculation with manual method of computation at different intervals for 13 HDR Ir-192 sources. Materials And Methods: We have retrospectively evaluate the in-house measured RAKR with the calibrated Standard Imaging HDR 1000 PLUS Well chamber /electrometer CDX 2000B for 13 HDR Ir192 sources with stated RAKR and the treatment time calculation accuracy of Oncentra TPS verified by manual method of computation using TG-43 formalism. Results: The study shows, that the measured RAKR and stated RAKR were well within the tolerance limits set by the national and international recommendations i.e. ±3 % for 13 HDR Ir192 sources. The verification of TPS treatment time calculation with manual calculation for single source as well as for multi-source lies within ±2%. Conclusions: There is good agreement between in-house measured and vendor quoted values of RAKR which shows that the chamber has been stable to better than ±3 % and manual calculations shows agreement with the TPS outcome within ±2% for 13 HDR Ir192 sources. The manual method of computation works reliably and reassures the TPS functioning.

Monitor unit verification for Varian TrueBeam VMAT plans using Monte Carlo calculations and phase space data.

To use the open-source Monte Carlo (MC) software calculations for TPS monitor unit verification of VMAT plans, delivered with the Varian TrueBeam linear accelerator, and compare the results with a commercial software product, following the guidelines set in AAPM Task Group 219. The TrueBeam is modeled in EGSnrc using the Varian-provided phase-space files. Thirteen VMAT TrueBeam treatment plans representing various anatomical regions were evaluated, comprising 37 treatment arcs. VMAT plans simulations were performed on a computing cluster, using 107 -109 particle histories per arc. Point dose differences at five reference points per arc were compared between Eclipse, MC, and the commercial software, MUCheck. MC simulation with 5×107 histories per arc offered good agreement with Eclipse and a reasonable average calculation time of 9-18 min per full plan. The average absolute difference was 3.0%, with only 22% of all points exceeding the 5% action limit. In contrast, the MUCheck average absolute difference was 8.4%, with 60% of points exceeding the 5% dose difference. Lung plans were particularly problematic for MUCheck, with an average absolute difference of approximately 16%. Our EGSnrc-based MC framework can be used for the MU verification of VMAT plans calculated for the Varian TrueBeam; furthermore, our phase space approach can be adapted to other treatment devices by using appropriate phase space files. The use of 5×107 histories consistently satisfied the 5% action limit across all plan types for the majority of points, performing significantly better than a commercial MU verification system, MUCheck. As faster processors and cloud computing facilities become even more widely available, this approach can be readily implemented in clinical settings.

A modified efficiency-NTU method (m-ε-NTU) for calculating air coolers in dehumidifying or frost conditions. Part I

In this part of the article, a literary review of the methods of stationary calculations of air coolers operating in dehumidifying or frost conditions is carried out. The approaches used at the moment are reviewed, namely: dehumidification coefficient method; logarithmic enthalpy difference method (LMED); equivalent dry-bulb temperature method (EDT); as well as -NTU method (efficiency number of heat transfer units) for calculating counterflow chilled water coils. Their main differences are shown and the key expressions used in them are given. A comparison of the advantages and disadvantages of the considered methods showed the rationality of using -NTU approach due to the possibility of its application for both design and verification calculations of heat exchangers. Since the classical -NTU method is not directly applicable to dehumidifying or frost conditions, it becomes necessary to adapt it to the calculations of air coolers of all types (both counterflow and parallel-flow air coolers without phase transition of the cooling fluid, and for cases with its phase transition) to correctly describe the effect of the above processes on heat exchange.

Study on Photochemical Properties of a Sr-SnS2/CaIn2S4 Heterostructure to Improve Cr(VI) Removal.

Compound semiconductor photocatalysis technology is considered to be a promising treatment for solving water problems efficiently. The point of designing high-efficiency catalysts is to optimize the band gap structure and facilitate the separation of charge carriers by establishing new electron migration pathways. Recently, 3D porous CaIn2S4 was found to have good photocatalytic ability. However, the quick recombination and agglomeration of carriers still limit its application. Herein, we prepared a heterostructure by introducing 2D Sr-doped SnS2 to 3D CaIn2S4 by a hydrothermal synthesis method. The optimal dosage of Sr-SnS2 is 3%, and the photocatalytic Cr(VI) removal efficiency of 3% Sr-SnS2/CaIn2S4 (SSCS-3) is 5.82 and 10.83 times those of pure CaIn2S4 and SnS2, respectively. According to the results of characterization tests and calculation verification, we inferred that the enhanced photocatalytic removal of Cr(VI) is due to the introduction of Sr-SnS2 that can promote the rapid transfer of photogenerated electrons to the surface of CaIn2S4, and the heterostructure formed between 2D Sr-SnS2 and 3D CaIn2S4 can also provide abundant reaction sites. The promotion of carrier separation is mainly due to the formation of a built-in electric field of the Sr-SnS2/CaIn2S4 heterostructure. This work provides new ideas and technologies for the treatment of Cr(VI) in wastewater.

Selection of an optimal cable brand for high-voltage overhead power lines based on criterion analysis

This paper is aimed at developing a versatile approach to selecting an optimal cable brand for overhead transmission lines for use in design practice, adapted to conventional and new-generation cable types. To implement multi-criterion evaluation of external factors and limitations when selecting a cable type, the methods of systems, hierarchy and comparative analysis were used. A method for selecting an optimal cable brand based on hierarchy analysis was developed along with an algorithm for its implementation when designing new or modernizing existing overheadlines. The developed approach is demonstrated on the example of construction and modernization of 220 kV overhead lines with the conventional AC cable and such new-generation domestic brands, as АСВТ, АСВП, АСк2у and АСТ. In the considered examples, the technical feasibility of the construction of a new overhead line was limited by the value of the sag. For the modernization project, the specific weight of the cable was of greater importance. The selection criteria included the span length, cable cost and admissible continuous current. The АСВП and АСТ cable brands showed the greatest compliance with the selection criteria (27.5% and 55.9%, respectively). Therefore, at minimum capital investments, the АСВП brand ensures the optimum span length in the construction of a new overhead line, whereas the ACT brand ensures the maximum capacity in the modernization of an existing line. The conducted verification calculations confirmed the feasibility and versatility of the proposed method for selecting a cable brand.

Sound absorption performance based on auxetic microstructure model: A parametric study

With the increasing prominence and complexity of environmental noise problems, there is an urgent need for novel acoustic materials to meet noise reduction requirements. In this paper, two auxetic microstructures and three typical lattice microstructures are established, and a microscopic-macroscopic acoustic performance study scheme is established through the Johnson-Champoux-Allard-Pride-Lafarge (JCAPL) model. Auxetic-BCC porous materials have lower acoustic resistance and reactance amplitudes than many typical porous materials through experimental verification and comparative analysis of numerical calculations. The porous material's thickness and the backing cavity's thickness have similar effects on sound absorption performance when controlling a single change in structural parameters, and there is an optimum thickness. As acoustic resistance and reactance are dominant at low and high frequencies, respectively, noise reduction is better at low (high) frequencies than at minor (large) porosity, and the porosity of 76.4%–82.0% has the best sound absorption effect. Changes in prism length of materials with high porosity are more sensitive than those with low porosity, so the prism length with porosity of 76.4%, 79.0%, and 82.6% shall be designed to be less than 1.1 mm, 0.9 mm, 0.8 mm, respectively. This study provides theoretical guidance for designing multifunctional porous materials in extreme environments.

Computer aided design of low voltage electrical installations

The paper proposes a method of calculation and rapid sizing of power circuits of electrical panels using a program made in-house. The proposed application has a friendly and very intuitive graphical interface, being easy to use due to the intelligent way of making the selection and data entry. This application emerged in response to the real need for fast and accurate sizing of low voltage electrical switchboards used in industry. The real help is provided by the mechanism that allows frequent and rapid modification of the technical solution to adapt to the ever-changing requirements dictated by the stages in the development of electrical projects.The operation of the program is based on the existence of an internal database materialized using several data tables containing various types of electrical consumers, switching and protection equipment and a series of standardized power cables from which they are automatically selected. The selection is made based on sizing and verification calculations with the help of intelligent selection methods so that only the equipment that matches the data provided by the user are selected ensuring an additional verification of the various omissions that may occur.The application is useful for designing of a new installation or for the verification of existing ones, allowing the rapid and even real-time observation of the influence of the various changes made to the project.

Small-Signal Analysis and Design of Constant On-Time Controlled Buck Converters With Duty-Cycle-Independent Quality Factors

This paper presents a frequency-domain analysis that models the behavior of Constant-on-Time (COT)-controlled Buck converters in wide-input-output-range scenarios. Based on this analysis, a design strategy is proposed to enable robust control with a duty-cycle-independent quality factor, also known as a constant <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$Q$</tex-math></inline-formula> -value. A constant <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$Q$</tex-math></inline-formula> -value circuit based on the proposed strategy is then constructed and incorporated with a baseline ultra-fast transient constant on-time (UFTCOT) control scheme to experimentally verify the system stability and optimal load transient response under wide input-output range scenarios. In addition, the design strategy is extended to other COT Buck control schemes with simulation and calculation verifications.

Predicting the three-dimensional grain structure of superalloys during vacuum arc remelting process

In order to study the influence of the vacuum arc remelting process (VAR) on the grain structure of the ingot and provide initial condition for the prediction and analysis of the subsequent process such as homogenization and billet forging, an efficient and accurate three-dimensional (3D) cellular automata method was developed for the VAR process, and all parts of the algorithm were rigorously verified, and it can be combined with the MeltFlow-VAR. An ingot of 718 alloy was smelted through experiment for calculation verification and proved the accuracy of the predictions. A new method for discretization of Euler angles to obtain orientation index is proposed and verified, which is more flexible and higher computationally efficient than previous algorithms. Aiming at the problem of a large number of cells and calculation time on large-scale VAR ingot in the future, a hybrid parallel scheme is designed, and it is expected to realize large-scale calculations on the supercomputer system. Finally, the effect of different cell sizes on the calculation results was also studied, and the grain size at the edge of the ingot was not affected by the cell size.

Impact of coastal island restoration engineering and subsequent tourism on migratory waterbirds: a 3‐year case from Southern China

Coastal engineering poses a significant threat to the survival of migratory waterbirds worldwide. However, the mechanisms through which engineering affects waterbirds are still unclear. To gain a better understanding of this issue, we conducted a three‐year survey of waterbirds on Shanxinsha Island, which underwent restoration engineering, along the East Asian–Australasian Flyway. We compared the seasonal migratory change among different species groups through and after the island restoration engineering. We observed a total monthly maximum count of 118,506 individuals from 61 waterbird species over the span of 38 months, including eight globally threatened species and five species that exceeded 1% of the flyway population. Throughout the survey periods, the average number of total waterbirds and small shorebirds observed during the migrating season decreased by 52.7 and 48.6%, respectively. The massive loss of high‐tide roosting areas was the primary factor contributing to this decline. The combined effects of increased vegetation and deeper water levels resulted in a 38.8% reduction in exposed tidal flat area, as determined through land cover verification and fractional vegetation cover calculations. While tourism activities exhibited fewer negative consequences compared to island restoration engineering, they had a greater impact on small breeding shorebirds. Our study showed that small shorebirds were particularly susceptible to island restoration engineering, whereas large shorebirds and swimming birds were more flexible in their use of roosting or foraging sites. We suggest that the impact of future coastal engineering requires more detailed assessment and monitoring, especially for small migratory shorebirds.

ОПРЕДЕЛЕНИЕ ОСТАТОЧНЫХ ПРОГИБОВ ИЗГИБАЕМЫХ ЖЕЛЕЗОБЕТОННЫХ ЭЛЕМЕНТОВ НА ОСНОВЕ НЕЛИНЕЙНОЙ ДЕФОРМАЦИОННОЙ МОДЕЛИ

The purpose of this work is to numerically implement the determination of residual deflections of reinforced concrete elements based on a nonlinear deformation model. To solve the equations in a physically nonlinear formulation, the iteration method is used in combination with Microsoft Excel and VBA. Most of the existing engineering methods for the verification calculation and reinforcement of bent elements are based on approaches based on the determination of integral stiffness characteristics of the section by simplified methods. This problem acquires new relevance when using the current norms, when it is necessary to take into account the features of nonlinear deformation of materials, loading mode, and the background of the structure. The article considers the application of a nonlinear deformation model in the calculation of residual deflections. To solve this problem, the bent element is divided into separate sections, on each of which stiffness is calculated based on a nonlinear deformation model. When solving systems of equilibrium equations of a nonlinear deformation model, the iteration method is used. In areas with cracks, the stresses in the reinforcement are adjusted by a coefficient that takes into account the unevenness of their distribution in the section with the crack and between them. After determining the stiffness coefficients in each section, the displacement is determined by integrating the values in the sections of unit moments and the calculated curvature by the numerical method of trapezoids. A load-deflection graph is constructed and approximated by a square polynomial with the derivation of an analytical dependence to determine the residual deflections as well as the stress-strain state of the bent elements as a whole. The analysis and comparison of the results with the normative methodology is given. Numerical example of calculation of good convergence with the normative methodology

Швидкість анігіляції позитронів у точкових дефектах реакторних матеріалів у модифікованій моделі Тао - Елдрупа

Theoretical concepts of the positron annihilation process in structural materials of nuclear reactors, taking into account the peculiarities of their electronic structure, have been developed. The Tao - Eldrup model, which allows to analytically calculate the lifetime of a positron in a spherically symmetric potential well, has been modified for the case of a potential well of finite height, in order to expand the limits of the model's application. The dependence of the positron lifetime on the height and width of the potential well, which occurs at the point defects, was determined. The results obtained within the framework of the modified model provide important information for the analysis of positron lifetime spectra in irradiated materials and data for the verification of quantitative calculations by the method of density functional theory.

Real-World Urban Light Emission Functions and Quantitative Comparison with Spacecraft Measurements

We provide quantitative results from GIS-based modelling of urban emission functions for a range of representative low- and mid-rise locations, ranging from individual streets to residential communities within cities, as well as entire towns and city regions. Our general aim is to determine whether lantern photometry or built environment has the dominant effect on light pollution and whether it is possible to derive a common emission function applicable to regions of similar type. We demonstrate the scalability of our work by providing results for the largest urban area modelled to date, comprising the central 117 km2 area of Dublin City and containing nearly 42,000 public lights. Our results show a general similarity in the shape of the azimuthally averaged emission function for all areas examined, with differences in the angular distribution of total light output depending primarily on the nature of the lighting and, to a smaller extent, on the obscuring environment, including seasonal foliage effects. Our results are also consistent with the emission function derived from the inversion of worldwide skyglow data, supporting our general results by an independent method. Additionally, a comparison with global satellite observations shows that our results are consistent with the deduced angular emission function for other low-rise areas worldwide. Finally, we validate our approach by demonstrating very good agreement between our results and calibrated imagery taken from the International Space Station of a range of residential locations. To our knowledge, this is the first such detailed quantitative verification of light loss calculations and supports the underlying assumptions of the emission function model. Based on our findings, we conclude that it should be possible to apply our approach more generally to produce estimates of the energy and environmental impact of urban areas, which can be applied in a statistical sense. However, more accurate values will depend on the details of the particular locations and require treatment of atmospheric scattering, as well as differences in the spectral nature of the sources.

TUNING AND VALIDATION OF THE NEW RADCALC 3D MONTE CARLO BASED PRE-TREATMENT PLAN VERIFICATION TOOL

Verification procedures for patient-specific quality assurance (QA) in advanced radiotherapy are laborious and time-consuming. Moreover, it has been shown that these procedures cannot detect some inaccuracies for some particular complex cases due to tissue inhomogeneity and highly modulated plans. Secondary dose calculation verification of radiotherapy plans is an important aspect in patient-specific QA. A suitably optimized software, RadCalc equipped with 3D Monte Carlo Module (MC), was used to dosimetrically verify radiotherapy treatment plans where the measured dose distributions can be inaccurate due to the TPS dose calculation algorithm and/or treatment unit delivery uncertainties. MC Models were built using specific commissioning measurements and then the Additional Radiation to Light Field Offset parameter (Dosimetric Leaf Gap parameter) was tuned to achieve the best dose comparison agreement with phantom patient-specific QA measurements. The results showed a good agreement between the TPS and the simulations. RadCalc MC also allows to better estimate the plan doses in lung cancer patients and to detect the presence of possible inaccuracies due to tissue inhomogeneity, which is not estimable with a homogeneous phantoms.

Effect of boundary layer thickness on supersonic combustion in a scramjet combustor

In this study, the effect of boundary layer thickness on supersonic combustion in an ethylene-fueled scramjet combustor under Mach 5.5 flight conditions is studied by employing experiments, numerical simulations, and theoretical modeling. The plate flow quantitative results show that the absolute thickness of the boundary layer is higher for a larger combustor. But the relative thickness is thin. Although boundary layer thickness changes greatly as the combustion chamber scale enlarges, the influence on the transverse jet and cavity flow is limited. In contrast, the combustion chamber scale change has a great impact on the combustion. More violent flames exist in large-scale combustion chambers. A theoretical model demonstrated that a large subsonic region led to a long fuel residence time, resulting in larger Damköhler numbers. This indicated that a large combustor could maintain large combustion. Based on the above analysis, although the relative thickness of the boundary layer is thinner, the absolute subsonic region of the boundary layer full of combustion is increased, which is conducive to intense combustion. In addition, a verification calculation of the 50 mm shortening isolation section is carried out. It is found from the flame cloud diagram and the quantitative wall pressure data that the combustion is significantly weakened.

PO-1987 Exvivo proton range uncertainty verification of dose calculation on CTand CBCT based synthetic ct

PO-1987 Exvivo proton range uncertainty verification of dose calculation on CTand CBCT based synthetic ct