Analysis Computer Code Research Articles

The α-generalized implicit method associated with Potra–Pták iteration for solving non-linear dynamic problems

Generally, direct time integration procedures are used for solving the equations of motion in transient analysis of structures with large displacements. In this context, we propose an algorithm that combines the α-Generalized implicit integration method with the Potra–Pták two-step iterative scheme. The free Scilab program develops a computer code for the non-linear dynamic analysis of plane frames with large displacements and rotations. The FEM corotational formulation discretizes the structures considering the Euler-Bernoulli beam theory. The null-length connection element described by the axial, translational and rotational stiffnesses simulate the behavior of the beam-column connection. Jacobi’s method and the Scilab’s spec function determine the natural frequencies. The developed program is used for modal and transient dynamic analyses of frame problems available in the literature. The numerical results show that the Potra-Pták scheme obtains approximate solutions with fewer cumulative iterations until convergence and shorter processing time compared to the standard Newton-Raphson scheme. Further-more, the results show that the type of beam-column connection affects the vibratory behavior of the structure as well as the values of its natural frequencies.

A Simple Computer Code for Result Analysis of University Graduates

A Simple Computer Code for Result Analysis of University Graduates

Design, assembly and testing of an upgraded aeroacoustics wind tunnel facility

The Aeroacoustics Laboratory in the Department of Aerospace Engineering at Penn State currently serves several areas of experimental research. Most notable in the laboratory is the Anechoic Chamber of which the Aeroacoustics Wind Tunnel is an integral part. In recent years the dominant areas of research have included model aircraft exhaust jets and model rotors for helicopter applications involving detailed noise experiments. In the jet noise area, the applications have included aircraft in both flyover and take-off configurations. In the flyover application the air flow surrounding the exhaust jet has a significant effect on the radiated noise and must be simulated to produce experimental results that will be most useful in preliminary design of noise suppression applications. The Aeroacoustics Wind Tunnel at Penn State serves the purpose for this simulation. During aircraft take-off, the aircraft airspeed is in a range exceeding 250 ft per second, or Mach number of over M = 0.22. In the years preceding 2022, the velocity of the free jet flow of the Penn State facility was limited to less than 200 ft/sec. This paper reports on a project to design upgrades to the existing wind tunnel to improve the test section flow velocity to values closer to the 250 ft/sec target. The approach began with a preliminary design of the return flow ducting to convert the open jet, open return wind tunnel to a closed return tunnel. The concept is to make use of the flow energy in the exhaust of the tunnel to boost the input energy to the inlet fan that drives the flow to the test section. An integral part of the preliminary design involved making use of an upgraded flow analysis computer code to predict the gain in test section velocity of the new facility. For the available horsepower of two fans in the facility, the configurations of the existing and upgraded wind tunnel were entered into this analysis code based on a quasi-one-dimensional formulation. The code included empirical data formulated to include the various shapes of the components of the tunnels. The relative flow velocities in each section used simple incompressible continuity to calculate all velocities in the component sections. The average dynamic pressure in each section is calculated from the flow (constant) density and the velocity squared. Each section had a non-dimensional pressure loss parameter calculated from empirical data (from the relevant literature). The basic code (using the Excel algorithms) was based on a predictor-corrector concept in which the calculation was initialized with the estimated velocity and pressure of the flow at the entrance to the test section. The loss in each following section is estimated to determine the loss in the total pressure and the cumulated loss compared to the gains made at the two fans in the circuit. The initial guess is adjusted based on the total pressure value at the end of the circuit. During the related experiments, measurements of the total and dynamic pressure were performed at several joints between sections and compared to the values predicted in the analysis code. Various settings of the horsepower of the drive fans were used and the results were compared to flow measurements for the tunnel configurations (predominantly for the open return and closed return tunnel setups available before and after the upgrade project.) Results of the analysis and experiments are presented and analyzed together with the remaining activities planned for the coming months.

MELCOR – DAKOTA coupling for uncertainty analyses in the SNAP environment/architecture

Uncertainty estimation to assess figures of merit characterizing evolution of a severe accident transient is a topic of current investigation in development of best-estimate plus uncertainty methodology. The probabilistic method to propagate input uncertainty is one of the methodologies used to develop Uncertainty Analyses (UAs). Using this methodology, UAs are performed by sampling probability distributions that describe the range of possible values that computer simulation model inputs can have. For each sample (or realization) of a set of uncertain input parameters, a computer simulation is performed. From the range of code simulation results obtained for each input realization, a distribution of code results is obtained. In this process, the distribution of input uncertainties is propagated to obtain a distribution of possible code results (i.e., the code output uncertainty). This probabilistic methodology is facilitated using Uncertainty Tools (UTs), which can be coupled with the accident analysis computer code to perform an UA. One of the UTs currently available is DAKOTA, developed by Sandia National Laboratories. DAKOTA is also provided as a SNAP plug-in. SNAP is a graphical user interface designed to support the use of USNRC codes (MELCOR, TRACE, etc). This paper is entirely derived from the NUREG/IA-532 issued by USNRC in April 2023 (Mascari et al., 2023) and has as a major target to summarize the main needs of UA in severe accident, the main element of the probabilistic method to propagate input uncertainty, and the workflow within SNAP to assist other interested analysts with their applications given they are members of the USNRC Cooperative Severe Accident Research Program (CSARP).

Laser Doppler Fluximetry in Cutaneous Vasculature: Methods for Data Analyses

Introduction: Acquisition of a deeper understanding of microvascular function across physiological and pathological conditions can be complicated by poor accessibility of the vascular networks and the necessary sophistication or intrusiveness of the equipment needed to acquire meaningful data. Laser Doppler fluximetry (LDF) provides a mechanism wherein investigators can readily acquire large amounts of data with minor inconvenience for the subject. However, beyond fairly basic analyses of erythrocyte perfusion (fluximetry) data within the cutaneous microcirculation (i.e., perfusion at rest and following imposed challenges), a deeper understanding of microvascular perfusion requires a more sophisticated approach that can be challenging for many investigators. Methods: This manuscript provides investigators with clear guidance for data acquisition from human subjects for full analysis of fluximetry data, including levels of perfusion, single- and multiscale Lempel-Ziv complexity (LZC) and sample entropy (SampEn), and wavelet-based analyses for the major physiological components of the signal. Representative data and responses are presented from a recruited cohort of healthy volunteers, and computer codes for full data analysis (MATLAB) are provided to facilitate efforts by interested investigators. Conclusion: It is anticipated that these materials can reduce the challenge to investigators integrating these approaches into their research programs and facilitate translational research in cardiovascular science.

Unique safety features and licensing requirements of the NuScale small modular reactor

Small modular reactors (SMR) offer a novel approach to the construction and operation of nuclear power plants. The NuScale VOYGR™ plant uses a simplified SMR design that is based on proven light-water reactor technology with substantial improvements in nuclear safety. It consists of a 250 MWt reactor core housed with other primary system components in an integral reactor pressure vessel surrounded by a steel containment vessel, all of which is immersed in a large pool of water that also serves as the ultimate heat sink. At the core of the NuScale safety case are three primary safety systems: the decay heat removal system, the emergency core cooling system, and the containment. The ability of the NuScale Power Module (NPM) passive safety systems to remove core decay heat for an unlimited duration is demonstrated through analysis of a beyond-design-basis extended loss of AC power with no replenishment of water to the ultimate heat sink or operator actions. The NuScale methodology to evaluate an indefinite loss of AC power uses the proprietary NRELAP5 systems analysis computer code. Analysis results show that the reactor coolant system liquid level above the core is maintained and that containment pressure remains below the vessel design pressure. Once full passive air cooling is established, containment pressure and temperature will decrease over time with decreasing core decay heat. NuScale received standard design approval in September 2020 and design certification in January 2023 for its 50 MWe NPM configured as a 12 module plant. NuScale is currently seeking standard design approval to increase its core power to 250 MWt, nominally 77 MWe per module, in a 6-module plant (VOYGR™-6) configuration. The high-level safety of NuScale’s SMR technology is foundational to a new standard of nuclear power plant resilience.

FORECASTING OF RADIOACTIVE CONTAMINATION OF ATMOSPHERIC AIR IN AN EXTREME SITUATION AT NPP

Problem statement. The task of assessing the level of atmospheric air radioactive contamination in the case of an extreme situation on the territory of the Zaporizhzhya NPP, which leads to an instantaneous radioactive aerosol emission, is considered. An analysis of the dynamics for the zones’ formation of radioactive contamination in the wind direction towards Nikopol is conducted. For the prompt solution of this of this forecast issue, the creation of a multifactorial numerical model is required, which allows for prompt analysis of the size and intensity of radioactive contamination areas. The purpose of the article. Creation of a numerical model and computer code for the operational analysis of radioactive contamination areas formed during the instantaneous release of radioactive pollutants into the atmosphere. Methodology. The computer code is based on a numerical model, which is a differential analogue of the multifactor kinematic equation of mass transfer of a radioactive impurity in atmospheric air. The mass transfer equation takes into account the wind speed field, atmospheric turbulent diffusion, and the intensity of radioactive substances emission into the air. For the numerical integration of the mass transfer equation, the splitting method is used followed by the use of finite-difference schemes. Determination of the volumetric activity value at each splitting step is implemented by an explicit formula. Scientific novelty. An effective numerical model was developed and its software implementation was conducted for operational analysis of the formation of radioactive contamination areas in the atmosphere during an extreme situation at a nuclear power plant, accompanied by the emission of radioactive substances. The model takes into account a complex of factors that affect the process of radioactive impurities spread in the atmosphere. Practical value. A computer code was developed for calculating the dynamics of the formation of radioactive contamination zones in the atmosphere based on the developed numerical model. This makes it possible to analyze the consequences of emergency emissions on the territory of the NPP using the computational experiment method. Conclusions. A mathematical model was developed for the operational analysis of radioactive contamination level of the atmospheric air due to an extreme situation at the nuclear power plant, which leads to an intense instantaneous release of radioactive substances. The results of a computational experiment based on the developed numerical model are presented.

Foreword to the special issue on new developments in structural stability.

Foreword to the special issue on new developments in structural stability.

Improvement in Runtime Speed for Frequency Domain Soil–Structure Interaction Analysis Using a Coarray Parallel Processing Technique

In this paper, we propose a new algorithm for introducing Coarray Fortran (CAF) into a program that dynamically analyzes the frequency domain in soil–structure interactions. This was implemented in KIESSI-3D, which is frequency domain soil-structure interaction analysis computer code based on finite and infinite element techniques, and the performance of analysis speed based on the number of images (or coarrays) and cores per image was evaluated. For the performance evaluation, we used examples of full-scale nuclear power plant buildings with a shallow foundation model as well as a deep foundation model. In terms of analysis speed, the new KIESSI-3D improved the analysis speed by an average of 2.78 times for the shallow foundation problem and 2.69 times for the deep foundation problem, compared with the existing KIESSI-3D, because of the new algorithm and CAF. Further, as the number of cores and the internal memory size in the computer systems increased, the efficiency of also parallel processing increased.

Numerical analysis of thermal-hydraulic safety for a reactor containment in the event of a main steam line break

The present work demonstrates the development of a numerical thermal-hydraulic (TH) model for the containment module of the PRABHAVINI code which is an in-house severe accident analysis computer code used for the analysis of Indian pressurized heavy water reactors (PHWRs). The model, for the analysis of the TH behavior of the containment under a postulated main steam line break (MSLB) situation inside it, incorporates the effect of nonlinear coupling among different heat and mass transfer chronologies such as heat transfer within the containment and through its walls, wall and interface condensations, condensation due to over saturation of the air and evaporation.The TH model accounts for the thermodynamic non-equilibrium between the air–vapor mixture inside the containment and the water likely to be accumulated at the bottom of the containment.For the comparison of the TH model developed, a more conservative case study is undertaken where a single containment is analyzed for an MSLB accident ceasing the possibility of any kind of leakage from it. The results obtained from the model developed are compared with those obtained from the RELAP5. Next, the model is extended for more realistic TH analysis of the multi-volume containment incorporating the possibility of uni- or bi-directional inter-volume leakages as well as leakages from the containment volumes to the atmosphere. The analysis demonstrates the effect of different heat and mass transfer phenomena on the critical TH field variables of the reactor containment for the MSLB situation under consideration.

The progress on the 3D whole-core neutronics calculation of PANGU code

PANGU code is a modern computer code for the physics analysis of pebble-bed high temperature gas-cooled reactors (HTGRs). This paper presents the recent progress on the development of PANGU’s capability in three-dimensional (3D) whole-core neutronics calculations. Firstly, diffusion and SP3 solvers based on nodal Green function method (NGFM) have been developed for the 3D whole-core calculation. Secondly, the 3D discrete-ordinate (Sn) neutron transport solver with coarse mesh finite difference (CMFD) acceleration has been developed to provide reference solutions, as well as being used for pre-homogenization calculations. Thirdly, two methods have been proposed for treating the strong absorbers in the framework of 3D whole-core diffusion calculations. Finally, the performances of the newly developed methods and solvers are tested by typical numerical cases based on HTR-10.

Effects of near‐fault acceleration and non‐acceleration pulses on pounding between in‐plan irregular fixed‐base and base‐isolated buildings

Concave surface sliders (CSSs) are considered as an effective solution for retrofitting adjacent buildings irregular in plan that could undergo significant seismic pounding due to torsional displacements. This is because during the sliding phase there is coincidence between the projection of the gravity mass centre of the superstructure and the stiffness centre of the CSSs. However, unexpected torsional pounding, with amplification in a near-fault site, may be induced by variability of friction force and lateral stiffness of the CSSs, depending on the axial load and friction coefficient changes during an earthquake. In this work, structural pounding between fixed-base and base-isolated reinforced concrete (RC) L-shaped buildings, placed adjacent to form T- and C-shaped plans, is investigated. A simulated design of the original fixed-base framed structures is preliminarily carried out in accordance to a former Italian code, for a medium-risk seismic zone and a typical subsoil class. Then, seismic retrofitting with CSSs is carried out, to attain performance levels imposed by the current Italian code in a high-risk seismic zone and for moderately-soft subsoil. A computer code for the pounding analysis between fixed-base and base-isolated test structures is developed, in order to compare effects of nonlinear models of the CSSs that consider constant and variable axial load combined with friction coefficient at breakaway and stick–slip and as function of the sliding velocity, axial pressure and rising temperature at the sliding interface. Attention is focused on the pulse-type nature of near-fault earthquakes generally observed in the velocity time histories but largely overlooked in the acceleration ones. To this end, automated classification algorithms using wavelet analysis are adopted to compile three datasets of seismic input distinguishing between no-pulse and velocity-pulse, the latter further categorised into non-acceleration and acceleration pulses and rotated along the direction most likely to contain strong pulses.

Analysis of Electric Go Kart

Abstract: The Electric Go-Karts use a knuckle as a significant a half of their steering systems, it controls the efforts applied further because the turning capacities. we tend to tend to area unit proposing modification within the materials used which can increase the strength of the knuckle. The recent technologies developed helps in reducing the strain and strains while not poignant the physical properties. at intervals the gift work we've got used SOLIDWORKS computer code for analysis of knuckle joints with varied materials and ranging hundreds. Steering knuckle plays a significant role during a vehicle linking the steering mechanism, wheel hub and brakes tothe vehicle body

Mathematical modeling of point kinetic equations with temperature feedback for reactivity transient analysis in MTR

Abstract The behavior of the nuclear reactor in response to any sudden change in reactivity is very important for reactor control. Positive reactivity insertions causes power excursion and could have a destructive impact on the reactor core. The aim of the study is to investigate the safety features of a material test reactor (MTR) during reactivity transient with emphasis on the capability of the mathematical modeling using programming language. Therefore a mathematical model using Python3.6; high-level programming language is developed to solve the point kinetic equations taking into account Doppler and moderator feedback effects. The model is validated with AIREKMOD_RR; point kinetic computer code for reactivity transient analysis in nuclear research reactors. The results of the Python model demonstrate the inherent safety features of the MTR reactor. Also, there is good agreement between the results of the Python model and AIREKMOD_RR code, illustrating the efficiency of the Python model in simulating the behavior of the reactor core under reactivity transient.

Development of IVR-ERVC evaluation method and its application to the SMART

An IVR (In-Vessel corium Retention) through ERVC (External Reactor Vessel Cooling) is known to be an effective means for maintaining the reactor vessel integrity during severe accidents in nuclear power plants. The evaluation method of the IVR-ERVC for small reactors was developed and applied to a small integral reactor of the SMART (System-integrated Modular Advanced ReacTor). As a first step, the thermal load analysis from the corium to the external reactor vessel wall is necessary. As a second step, the natural circulation mass flow rate analysis, which is formed in the annular gap between the external reactor vessel wall and insulator, is necessary using the thermal hydraulic computer code. The CHF (Critical Heat Flux), which is the maximum heat removal rate from the external reactor vessel wall depending on the estimated natural circulation mass flow rate, is determined using experimental results. The success criteria of the IVR-ERVC to prevent reactor vessel failure during severe accidents is determined by comparing of the thermal load with the CHF. Finally, a structure analysis on the reactor vessel wall performs to evaluate the structure integrity of the reactor vessel wall in ERVC condition using the structure analysis computer code. Consequently, the IVR-ERVC strategy turned out to be an effective means for maintaining the SMART reactor vessel integrity during severe accidents from the thermal load analysis, CHF analysis, and structure integrity analysis.

OKBM Afrikantov Experience in Developing Methods and Computer Codes for Reliability Analysis and Probabilistic Safety Analysis of Nuclear Installations

The history of the development and adoption of reliability analysis of equipment and systems as well as probabilistic safety analysis in the practice of design and operation of nuclear installations is presented. The basic characteristics of the developed software systems for performing probabilistic safety analysis of installations during the design process, risk monitoring during operation of NPP, reliability monitoring of ship installations, and nuclear power plants operating as intended as well as information about their adoption in operating facilities are presented. It is shown that digital technologies are being actively adopted in the analysis and monitoring of safety.

Modeling viscous damping in nonlinear response history analysis of steel moment‐frame buildings: Design‐plus ground motions

AbstractInvestigated in this paper is the question: Can seismic demands on steel moment‐frame buildings due to maximum considered earthquake (MCER) design‐level ground motions (GMs) be estimated satisfactorily using linear viscous damping models or is a nonlinear model, such as capped damping, necessary? This investigation employs an enhanced model with several complex features of a 20‐story steel moment‐frame building. Considered are two linear viscous damping models: Rayleigh damping and constant modal damping; and one nonlinear model where damping forces are not allowed to exceed a predefined bound. Presented are seismic demands on the building due to two sets of GMs: MCER design‐level GMs (2% probability of exceedance [PE] in 50 years) and rarer excitations (1% PE in 50 years). Based on these results, we conclude that linear damping models are adequate for estimating seismic demands on steel moment‐frame buildings—designed to satisfy current story drift and plastic rotation limits due to MCER design‐level GMs. Between the two linear damping models, constant modal damping is preferred; it is available in commercial computer codes for earthquake structural analysis.

A two-dimensional limit equilibrium computer code for analysis of complex toppling slope failures

Evaluation of blocky or layered rock slopes against toppling failures has remained of great concern for engineers in various rock mechanics projects. Several step-by-step analytical solutions have been developed for analyzing these types of slope failures. However, manual application of these analytical solutions for real case studies can be time-consuming, complicated, and in certain cases even impossible. This study will first examine existing methods for toppling failure analyses that are reviewed, modified and generalized to consider the effects of a wide range of external and dead loads on slope stability. Next, based on the generalized presented formulae, a Windows form computer code is programmed using Visual C# for analysis of common types of toppling failures. Input parameters, including slope geometry, joint sets parameters, rock and soil properties, ground water level, dynamic loads, support anchor loads as well as magnitudes and forms of external forces, are first loaded into the code. The input data are then saved and used to graphically draw the slope model. This is followed by automatic identification of the toppling failure mode and a deterministic analysis of the slope stability against this failure mode. The results are presented using a graphical approach. The developed code allows probabilistic introduction of the input parameters via probability distribution functions (PDFs) and thus a probabilistic analysis of the toppling failure modes using Monte-Carlo simulation technique. This allows calculation of the probability of slope failure. Finally, several published case studies and typical examples are analyzed with the developed code. The outcomes are compared with those of the main references to assess the performance and robustness of the developed computer code. The comparisons demonstrate good agreement between the results.

High-frequency random vibrations of a stiffened plate with a cutout using energy finite element and experimental methods

In this paper, by employing the energy finite element analysis, the high-frequency vibrations of a stiffened plate having a cutout, subjected to random vibrations, have been analyzed, and the obtained results have been validated by use of experimental methods. By using equations for joining of structures, energy finite element analysis computer codes were developed for the coupling of beam-plate elements. Finally, a plate containing a cutout and three stiffeners was fabricated and subjected to high-frequency random vibration tests. The results of the prepared codes were compared with the results of experiments. These comparisons indicated that at high frequencies, the energy finite element analysis can be used as an effective tool in the analysis of high-frequency vibrations.

Комплекс программ для численного анализа электровакуумных приборов клистронного типа.

Комплекс программ для численного анализа электровакуумных приборов клистронного типа.