Reliability Of Simulation Results Research Articles

INFLUENCE OF SPACE CHARGE BREAKDOWN ON THE PERFORMANCE OF ELECTROMEMBRANE SYSTEMS

The article provides an overview of methods for solving problems of forecasting time series and modeling of complex systems using fuzzy cognitive maps (FCM). The main algorithms used in solving practical problems for complex semi-structured systems are listed, which make it possible to improve the accuracy and reliability of simulation results. For completeness of the review, publications of Russian and foreign researchers working in this area have been studied and described. In addition, the main software tools that implement the existing algorithms were listed and their distinctive features for solving various classes of problems were given. This comparison of software packages allows users to deter-mine the optimal system for further theoretical or practical research

New damage model for simulating radiation-induced direct damage to biomolecular systems and experimental validation using pBR322 plasmid

In this work, we proposed a new damage model for estimating radiation-induced direct damage to biomolecular systems and validated its the effectiveness for pBR322 plasmids. The proposed model estimates radiation-induced damage to biomolecular systems by: (1) simulation geometry modeling using the coarse-grained (CG) technique to replace the minimum repeating units of a molecule with a single bead, (2) approximation of the threshold energy for radiation damage through CG potential calculation, (3) calculation of cumulative absorption energy for each radiation event in microscopic regions of CG models using the Monte Carlo track structure (MCTS) code, and (4) estimation of direct radiation damage to biomolecular systems by comparing CG potentials and absorption energy. The proposed model replicated measured data with an average error of approximately 14.2% in the estimation of radiation damage to pBR322 plasmids using the common MCTS code Geant4-DNA. This is similar to the results of previous simulation studies. However, in existing damage models, parameters are adjusted based on experimental data to increase the reliability of simulation results, whereas in the proposed model, they can be determined without using empirical data. Because the proposed model proposed is applicable to DNA and various biomolecular systems with minimal experimental data, it provides a new method that is convenient and effective for predicting damage in living organisms caused by radiation exposure.

An Optimal Model for Designing and Executing Windows in Tabriz Residential Buildings to Reduce Energy Consumption

Most of today's buildings, due to improper imitation of the architecture of buildings in other countries, are forced to use more energy to create conditions of thermal comfort. Building windows affect energy efficiency. So, the aim of this research is to be concerned with Tabriz climate; in selecting the proportion and suitable glazing of the windows, in order to access the best design and execute a model to decrease energy consumption. The research approach is to utilize simulation and Design Builder software as a research tool. So, the annual gas consumed in the Building was received from the National Iranian Gas Company and a case study is modeled and after converting the unit from kWh to kg and kg to m3 and reliability of simulation results. Then, through parametric optimization, eight scenarios in designing windows and through the genetic algorithm, the glazing coating were evaluated. The simulations were performed again and the results index was examined. Eventually, based on the analysis of outputs, according to fixed area, it is more suitable to replace windows with the height of 1.5 to 1.74 meters instead of windows with the height of 1 or 1.2 meters. A window should be replaced with 2, 3, 4 or 5 windows with the same fixed area. I is desired to superseded triple-glazed glazing with low-emissivity filled with argon gas with clear double-glazed glazing filled with air to reduce energy consumption. The amount of heat losses for the window height of 1 to 1.5m, from one window to five windows and for the clear double-glazed glazing filled with air were 2.04%, 11.11%,. and 45.36%, respectively.

Calibration of discrete element microparameters of coal based on the response surface method

Materials properties can be obtained using the discrete element method through appropriate parameter settings. The accuracy of setting parameters affects the reliability of simulation results. To accurately simulate the mechanical properties of coal, the discrete element models of coal were established. The effects of the parameters of the bonded-particle model on the macroperformance of coal were studied based on the response surface method. The simulation results showed that when the normal contact stiffness per unit area, the shear contact stiffness per unit area, critical normal stress, and critical shear stress are 3.066 × 1012 N/m3, 5 × 1011 N/m3, 2.747 × 107 Pa, and 1.424 × 107 Pa, respectively, the bonded parameters reliably simulated the crushing characteristics of long-flame coal. The increase in stiffness causes the model to fracture earlier but has less impact on the peak value; the strength has a greater impact on the mechanical properties of the model. In this study, the reliability of the comparison between the simulation and test was improved, and a basis was provided for the discrete element parameter calibration of the coal and the setting of simulation parameters for shearer cutting.

Uncertainty Analysis of Water Budget for Jinan Spring Basin Based on Numerical Model

Groundwater numerical simulation is affected by many uncertain factors, which directly influence the precision and reliability of simulation results. Therefore, it is very important to analyze the influence of these factors. This paper studied the influence of the uncertainty of sources and sinks on the water budget and the effect on the constant spring flow. Jinan spring basin was chosen as a case study, and a groundwater numerical simulation model was established. In the model, precipitation, groundwater exploitation, and boundary conditions are selected for the local sensitivity analysis. The analysis showed that precipitation is the most important factor affecting the water budget in Jinan spring basin, whilst groundwater exploitation is the most sensitive factor for spring flow. Upon consideration of the impact of these two factors, six different scenarios were developed for the numerical simulation, and quantitative analysis was conducted of the impact of the uncertainties from the sources and sinks on Jinan spring. The results of this study can provide a scientific reference for the effective use of groundwater resources on the constant gushing of Jinan springs.

Determine method of effective experimental period of similar material model for improving the simulation results

ABSTRACT Similar material simulation methods have been extensively applied to investigate stratum movement in mining technology. The similarity between similar material models and prototypes is directly associated to the reliability of simulation results. Considering that the mechanical strength changes of similar material model made at a certain ratio is closely related to its humidity and moisture content, the effective time period for simulating excavation and model monitoring should be determined based on the changes in humidity and moisture content of similar material models, but there is currently no such method. According to the relation of humidity and moisture content of the similar material model obtained through mechanical experiments, an approach is proposed for determining the effective experimental time for similar material model for coal mine stratum movement. The new device designed can effectively monitor the humidity changes of similar model materials, so that the simulation excavation and monitoring time process of similar material models can be scientifically controlled. This paper solves the difficult issue that the model dynamics similarity can hardly guarantee during the experiment of similar materials simulation, and the findings can offer a scientific basis for monitoring period of similar material models and reliability improvement for model simulation results.

Influencing analysis of different baffle factors on oil liquid sloshing in automobile fuel tank

Oil liquid sloshing is a common phenomenon in automobile fuel tank under variable working conditions. Installing baffles in automobile fuel tank is the most effective way to suppress adverse influence caused by oil liquid sloshing. Different types of three-dimensional finite element models filling oil liquid are created, meshed, and simulated. The reliability of simulation results is verified by test. The concept of time–area value is proposed in this work. In order to explore the influence of different baffle factors on oil liquid sloshing, six factors are studied. Six kinds of influencing factors are height, structure, shape, spacing, number, and placement of baffles. The sloshing pressure and time–area value are the core parameters for evaluating the influence degree. Some results could be obtained by comparing the parameters of oil liquid sloshing under the same condition. High baffles and baffles with small spacing have obvious attenuation influence on the pressure of oil liquid sloshing. Low baffles, double baffles, parallel baffles, and the combined action of inertia force and gravity are more beneficial to the reduction of time–area value. Time–area value is the largest and the smallest in fuel tank with intersection baffles and low baffles, respectively.

The impact of thermophysical properties and hysteresis effects on the energy performance simulation of PCM wallboards: Experimental studies, modelling, and validation

This paper presents a combined experimental and numerical procedure, developed to test the thermophysical behaviour of a real scale PCM wallboard, aiming at providing reliable data for the validation of building energy performance simulation tools. Data obtained from two experimental tests, conducted on real building elements integrating PCM undergoing complete and incomplete phase change, are considered for assessing the impact of thermal properties and hysteresis. A comprehensive comparative numerical analysis, performed by means of an in-house developed simulation tool, called DETECt, is carried out to investigate the reliability of several modelling and simulation approaches available in literature.Monitored data are used to compare the reliability of several modelling and simulation approaches (three different specific heat curves and four modelling approaches for hysteresis) to find out the appropriate temperature dependent heat capacity curves which realistically describe the PCM performance. ResultsThe use of cp – temperature curves characterized through thermophysical analysis (e.g. DSC) under conditions much different than those that the PCM can undergo during the operation of a building can lead to significant discrepancies in performances with the actual data. Moreover, in case of incomplete phase transitions, the lower the accuracy of the cp – temperature curves, the higher the influence of the hysteresis modelling approach on the reliability of simulation results; a better agreement between monitored data and simulation results is observed when hysteresis is modelled by considering the transition between heating and cooling (and vice versa), by switching from the melting to the solidification curves according to the liquid and solid mass fraction.The study shows that the more refined modelling of the phase change allows results to be consistent with the thermo-physics phenomena of composite PCM under real conditions and achieve more reliable results.

Short-Term Failure Warning for Transmission Tower Under Land Subsidence Condition

Crustal movement and land subsidence will cause tower foundation settlement, which seriously affects the safety of transmission line operation. This paper proposed a short-term failure warning method for transmission tower under land subsidence condition based on finite element method, strain monitoring and time series prediction. By simulating the stress distribution of the tower in actual foundation settlement, the weak components of the settlement tower were founded. Combined with the finite element simulation results in various conditions, the reliability of simulation results is verified, and the strain variation range of the corresponding measuring point is obtained. By installing the real-time strain monitoring system and establishing the autoregressive integrated moving average (ARIMA) time series forecast model, warning of the failure of the tower can be sounded in short time according to the strain monitoring and forecasting results. The field results show that the tower is in good condition and with no risk in short term. The method proposed by this paper is economical and easy to operate, which can be used to conduct the emergency treatment of the dangerous tower under land subsidence condition.

Prediction and Control of Asymmetric Bead Shape in Laser-Arc Hybrid Fillet-Lap Joints in Sheet Metal Welds

The shape and size of a weld bead - consisting of outer weld surface and inner fusion boundary - are important quality and strength attributes in sheet metal welds. The asymmetricity coupled with additional controlling parameters makes it challenging to predict the bead shape in laser-arc hybrid fillet-lap joints with use of lower order nonlinear analytical mathematical functions. An artificial neural network is designed to address the challenge, considering the welding speed, wire feed speed, voltage, current, and laser power as inputs. The experimentally obtained weld bead profiles are digitized in polar coordinates (r, θ) and thereby many input-output pairs are made available for training even with a limited number of experiments. An optimized neural network topology is presented with an assessment of reliability of simulation results. A rational approach for determining the number of coordinate points needed to accurately map the weld bead profile is an important contribution from the present investigation. The parametric study elucidates the effects of input parameters on geometry of the weld beads. The neural network exhibits the capability of capturing the process physics - demonstrated through the analysis of the weld dilution obtained from the simulation results. The welding speed and wire feed speed signifyingly affect the bead shape while the laser power has a minor impact. The laser, even though with less power, improves the weld dilution due to preheating of the base plate and stabilization of the welding arc.

Model Correction and Optimization Framework for Expedited EM-Driven Surrogate-Assisted Design of Compact Antennas

Design of compact antennas is a numerically challenging process that heavily relies on electromagnetic (EM) simulations and numerical optimization algorithms. For reliability of simulation results, EM models of small radiators often include connectors that significantly contribute to evaluation cost. In this letter, a response correction method for antenna models without a connector, based on a so-called network unterminating concept, has been proposed. Unterminating allows for obtaining electrical parameters of the connector embedded in the EM antenna model. They can be then utilized to refine the reflection responses of the EM antenna model without the connector. The refined model has been optimized using a novel trust-region-based method. It exploits the information gained from unsuccessful iterations to improve the accuracy of the model and prevent premature convergence of the algorithm. The proposed design approach has been demonstrated using two antenna structures and compared to benchmark algorithms.

Comparative study on turbulence models simulating inorganic particle removal in a Pista grit chamber

ABSTRACTNumerical simulations and experimental validations were conducted to determine grit removal efficiency and separation processes for inorganic suspended solids (ISS) with different particle sizes in a vortex-type grit chamber (Pista). The Euler–Lagrange method was used to simulate solid–liquid two-phase flow; the Unsteady Discrete Model was used to simulate the solid phase; and the Renormalization Group k-epsilon (RNG k-ε), Realizable k-epsilon (Real k-ε), and Shear Stress Transmission k-ω (SST k-ω) models were used to simulate the liquid phase. Results of the RNG k-ε model agreed well with the experimental results for particles with d ≤ 200 µm, with an average error of 7.10% (d < 100 µm) and 6.78% (100 µm ≤ d ≤ 200 µm). When particle size exceeded 200 µm, the Real k-ε model had the minimum average error (4.16%). Bed load transport and suspended load transport of the different size ISS particles presented in the grit chamber were important factors influencing grit removal efficiency. Pressure gradient and turbulence intensity distributions simulated by the three turbulence models were significantly different. Particles with diverse sizes reacted distinctly to the disturbance effect caused by pressure difference, which impacted on the accuracy and reliability of simulation results.

Simulation of soil water movement under subsurface irrigation with porous ceramic emitter

Subsurface irrigation has been achieved by using ceramic emitters, pitchers, pots and ceramic tubes, which have gained a certain degree of interest in arid regions due to their efficient use of water. Research on the formation of wetting patterns around the ceramic emitter is essential for the design of irrigation system. In this study, numerical simulations were carried out to investigate the effects of emitter installation method, emitter buried depth, emitter structural parameters, irrigation doses and initial soil water content on the wetting patterns in clay loam with Hydrus-2D. Finally, two field application experiments were conducted to test the practicality and reliability of simulation results. The simulation results were in good agreement with the experimental data. Results showed, emitter installation method had the least effect on the wetting pattern. A 25cm buried depth would be suit for irrigating vegetables, a 45cm deep buried depth would suit for irrigating fruit trees. The structure parameters had a significant effect on cumulative fluxes and horizontal wetting front, the structural parameters (emitter length is 7.00cm, emitter external diameter is 1.25cm, and emitter inner diameter is 0.60cm) would be a better fabricate parameters for ceramic emitter. Wetting front increased with increasing irrigation doses and initial water content. To prevent percolation, when the initial water content was high, it should be better to cut down the irrigation duration of ceramic emitter. The field results indicated that Hydrus-2D could be used to investigate the suitable parameters for ceramic emitter in subsurface irrigation systems and determine the suitable arrangement and operation mode of ceramic emitter.

Comparison of theoretical and experimental results for band-gap-graded CZTSSe solar cell

The simulation of CZTSSe solar cells is presented in this paper. The simulation results are in reasonable agreement with the experimental data, indicating the reliability of simulation results. New structure is proposed to increase the functionality of the cell. Improved functional performances are achieved by inserting a P-Silicon (P-Si) layer as back surface field. Simulation results suggest that by inserting this P-Si layer, efficiency of the CZTSSe solar cell increases from 12.6% to 16.59%, which is a significant improvement. For the champion cell JSC = 36.27 mA/cm2, VOC = 0.625 V and FF = 73.11% has been achieved.

Momentum transport between two granular phases of spherical particles with large size ratio: Two-fluid model versus discrete element method

Two-fluid Eulerian method is widely used in computer simulations of gas–solid systems such as fluidized beds. The models for describing drag forces play key roles in the reliability of simulation results. The solid–solid drag model is calculated by the formulas such as Syamlal-O'Brian's model [Syamlal, M. The particle–particle drag term in a multiparticle model of fluidization. Topical report, DOE/MC/21353-2373, NTIS/DE87006500, National Technical Information Service, Springfield, VA. 1987]. However, the performance of the model has not been examined in the mixtures of solid phases with a large size ratio between the particles of the phases, which is found in fluidized beds containing biomass particles (big particles) and the neutral phase particles (small particles) such as sand. The present study compares the results of Eulerian simulations using the Syamlal-O'Brian's formula with the results of Lagrangian simulations performed by the discrete element method (DEM) in the bidisperse mixtures of the size ratio of 10. Results suggest a significant difference between the Eulerian model and the DEM, which is basically due to the inhomogeneities triggered by the existence of large particles. The current methodology can be used to present correction factors for the solid–solid drag forces in Eulerian simulations for the bidisperse mixtures of large size ratios.

Numerical Simulation of Misrun Defect of Bimetallic Composite Pipe by Investment Casting

The casting and solidification process of the bimetallic composite pipe were simulated by ProCAST software aiming at the misrun defect in the pipe. The causes of defect were analyzed from the factors of the pouring temperature, pouring time, preheating temperature of mold and the height of sprue. Reasonable improvements were presented based on the simulation results. Industrial tests showed that misrun defect disappeared after the process was improved, which in turn verified the effectiveness and reliability of simulation results.

Numerical Simulation on Electrical-Thermal Properties of Gallium-Nitride-Based Light-Emitting Diodes Embedded in Board

The electrical-thermal characteristics of gallium-nitride- (GaN-) based light-emitting diodes (LED), packaged by chips embedded in board (EIB) technology, were investigated using a multiphysics and multiscale finite element code, COMSOL. Three-dimensional (3D) finite element model for packaging structure has been developed and optimized with forward-voltage-based junction temperatures of a 9-chip EIB sample. The sensitivity analysis of the simulation model has been conducted to estimate the current and temperature distribution changes in EIB LED as the blue LED chip (substrate, indium tin oxide (ITO)), packaging structure (bonding wire and chip numbers), and system condition (injection current) changed. This method proved the reliability of simulated results in advance and useful material parameters. Furthermore, the method suggests that the parameter match on Shockley's equation parameters, Rs, nideal, and Is, is a potential method to reduce the current crowding effect for the EIB LED. Junction temperature decreases by approximately 3 K to 10 K can be achieved by substrate thinning, ITO, and wire bonding. The nonlinear-decreasing characteristics of total thermal resistance that decrease with an increase in chip numbers are likely to improve the thermal performance of EIB LED modules.

3-Dimensional profile distortion measured by stylus type surface profilometer

In this paper, the distortion effect in measured profiles caused by stylus tip radius size of stylus-typed surface profilometer was analyzed in terms of 2D and 3D. On the basis of our analysis results, we propose selection criteria for the stylus tip radius to improve the reliability of measurement results. For this purpose, a simulation algorithm has been devised and implemented for 2D and 3D measurement simulations, and the 3-dimensional surface texture used in simulation was obtained using an Atomic Force Microscope (AFM) on an actual machined surface to improve the reliability of simulation results. The simulation results are compared with the measured results from the same specimen using a roughness tester, and the validity of analysis via the simulation proposed in this study is confirmed. Cumulative power spectral analysis was performed for the 2D and 3D simulated profiles obtained from simulation. On the basis of the analysis results, an effective frequency components field using a stylus type profilometer is clarified, and the selection criteria of the stylus tip radius for measurement is proposed considering the surface texture characteristics of the specimen. The purpose of this paper is to provide a basis of a simple and effective method which could be an alternative of some engineering standard that specifies selection of stylus tip radius for the measurement using only nominal Rq for machined surface.

Drilling Simulation of High Manganese Steel Processing Based on the J-C Constitutive Relation

The finite element physical model of the high-manganese steel drilling has been established on Johnson-Cook (J-C) constitutive equation derived using experimental methods. Through simulation, the variation of drilling force and heat is given and stress and temperature nephograms in cutting zone is obtained. A comparative study of the experimental data and simulation values is carried out using drilling force measurement system self-designed and developed, which proves the accuracy and reliability of simulation results and the model.

Research on CAN Bus of Pure Electric Vehicles Based on SAEJ1939

The use of CAN bus network on electric vehicles is of great significance, it can not only greatly reduce the costs of electric vehicles, but also increase the driving distance of electric vehicles. The stability of CAN bus load rate and CAN network communication rate plays a vital role to the CAN network，by studying and making use of SAEJ1939, this paper develops a vehicle network topology, then through calculating the bit rate of transfer time to calculate the load rate, combined with using the software named CANoe from the Vector company in Germany to analyse and simulate the sending cycle of each CAN bus node on pure electric vehicles. In this way,this paper analyses the reasonableness of CAN network design of the vehicle body. Finally this paper applies the on-site verification to prove the reliability of simulation results. This study is based on SAEJ1939 agreement CAN2.0B, did not make a study for CAN2.0A, so there are limitations, the findings may not apply to CAN2.0A.