Validation Of Dynamic Model Research Articles

The oil & gas upstream cycle: Development and production

This note focuses on the development and production phases of the oil & gas upstream cycle. The first one includes all activities and processes required to optimally develop a field. The second one is related to all activities performed to extract hydrocarbons from a reservoir and their treating at surface. The development phase is very complex and plays a very important role in a company’s strategy. In order to govern the process in each step and to obtain the best results in terms of profitability, risk reduction and safety, the oil companies have defined precise guidelines and try to adopt the most innovative technological solutions in the performed studies. According to these guidelines each project is based on a phase/gate approach and each phase has a set of clear objectives that, once achieved, allow the project to proceed into the next phase. During the development phase a set of studies are executed to ensure that asset development and project execution will be done at the best minimizing uncertainties and associated risks. The activity of reservoir characterization is the most important of these studies as its results have a strong impact on the final decisions. The objective of a reservoir evaluation study is the construction of a 3D model of the reservoir through a multi-step process that uses dedicated software. The purposes of this activity include improving the estimation of oil in place and reserves, predict future production, evaluating different development scenarios. While the development phase is optimized to be as short as possible, the production phase can last several years depending on the size of the field and the costs the company has to bear to maintain the system working. During its production life the field is continuously monitored through an activity called Reservoir Management. The objectives of the Reservoir Management activity include the continuous update and validation of the reservoir dynamic model and the definition and assessment of the technical and economical feasibility of well interventions aimed at field production optimization. Many studies in this phase are focused on the selection of the best oil recovery technique. Among them Enhanced Oil Recovery (EOR) techniques, although more expensive, are gaining high popularity as they provide a way to recycling CO2 created by industrial processes. The last part of this note is dedicated to an overview of what the oil companies and Eni in particular are doing or planning in order to meet the targets defined in the Paris agreements in terms of reduction of greenhouse gases emissions while still satisfying the world’s energy needs. Since renewables still have economic and technological limits when deployed on a large scale, Eni is promoting gas as an ideal partner for the development of renewables and is increasing the share of natural gas in its portfolio. The use of the gas-renewables mix also enables coal consumption to be reduced. New technologies are expected to play a key role on this journey towards a more sustainable model thus Eni is continuously increasing its budget in research and development projects for carbon neutrality.

The Integrated Test Analysis Process for Structural Dynamic Systems

Abstract Over the past 60 years, the U.S. aerospace community has developed, refined, and standardized an integrated approach to structural dynamic model verification and validation. One name for t...

A Novel Compact dq-Reference Frame Model for Inverter-Based Microgrids

The development and the experimental validation of a novel dynamic model of an islanded three-phase Inverter-based Microgrid (IMG) is presented in this paper. The proposed model reproduces the relevant system dynamics without excessive complexity and enough accuracy. The dynamics of the IMG are captured with a compact and scalable dynamic model, considering inverter based distributed generators with d-current droop primary and proportional resonant inner controllers. The complete development of the model, the practical assumptions, and the accurate proportional power sharing of the primary control technique are shown. The accuracy performance was verified in experiments performed at the Aalborg Intelligent Microgrids Laboratory for an islanded IMG case.

Time series analysis and forecasting with ECOTOOL.

This paper presents ECOTOOL, a new free MATLAB toolbox that embodies several routines for identification, validation and forecasting of dynamic models. The toolbox includes a wide range of exploratory, descriptive and diagnostic statistical tools with visual support, designed in easy-to-use Graphical User Interfaces. It also incorporates complex automatic procedures for identification, exact maximum likelihood estimation and outlier detection for many types of models available in the literature (like multi-seasonal ARIMA models, transfer functions, Exponential Smoothing, Unobserved Components, VARX). ECOTOOL is the outcome of a long period of programming effort with the aim of producing a user friendly toolkit such that, just a few lines of code written in MATLAB are able to perform a comprehensive analysis of time series. The toolbox is supplied with an in-depth documentation system and online help and is available on the internet. The paper describes the main functionalities of the toolbox, and its power is shown working on several real examples.

Theoretical analysis of dynamic characteristics in linear compressors

Linear compressor technology is characterized by the absence of a crank mechanism, which has gained increasing attention in vapor compression systems due to its compactness and lower friction losses in comparison to conventional reciprocating compressors. Limited work was found in the open literature related to the development and in-depth validation of a comprehensive linear compressor dynamic model that couples thermodynamic aspects with both mechanical and electrical sub-models. This paper presents a comprehensive and generalized simulation model that is used to simulate the dynamic performance of a linear compressor. The model is based on mass and energy balance equations applied to open control volumes. The overall model is composed of several sub-models including the piston dynamics, electrical motor, valve dynamics, and leakage flows. The thermodynamic model and the sub-models are integrated into a compressor overall energy balance that describes the different heat flows and losses. The linear compressor model is able to predict both transient and steady-state behaviors of the piston movement, internal pressure and temperatures as well as the overall performance. Comparisons of predicted and measured mass flow rates as a function of operating frequency are also presented within this work.

Velocity measurements in convective boiling flow using radioactive particle tracking technique

AbstractThe design, performance, and safety analysis of nuclear reactors, in particular boiling water reactors, requires information about the vapor–liquid flow dynamics. Such data are necessary for stand‐alone analysis of the thermal hydraulics, as well as to serve as a database for validation of computational fluid dynamics models. Challenges in collecting such data are magnified in the context of flow boiling, which is known to be a complex, multi‐scale problem. The present work focuses on investigating the two‐phase flow dynamics of convective boiling flows on a test section equipped with different heater rods arrangements. Noninvasive radioactive particle tracking (RPT) has been used for measuring liquid velocity field, mean flow patterns, and turbulent kinetic energy of the liquid phase. A novel tracer particle reconstruction algorithm based on support vector regression has been applied in this study. This is the first application of RPT for measuring liquid velocity fields in convective boiling flows.

Overview of the fixed base correction method for modal testing on dynamic boundary conditions

Modal tests are important steps in the validation of structural dynamic finite element models of test articles. Often, inadequate boundary conditions require more effort to be spent correlating the boundary condition or support structure rather than the test article. Recently, boundary condition correction methods, such as the fixed base correction method, have been developed to extract fixed based mode shapes for test articles on dynamic test fixtures. This paper presents an overview of the fixed base correction method and provides examples of the implementation to academic and representative test articles.Modal tests are important steps in the validation of structural dynamic finite element models of test articles. Often, inadequate boundary conditions require more effort to be spent correlating the boundary condition or support structure rather than the test article. Recently, boundary condition correction methods, such as the fixed base correction method, have been developed to extract fixed based mode shapes for test articles on dynamic test fixtures. This paper presents an overview of the fixed base correction method and provides examples of the implementation to academic and representative test articles.

A new three-dimensional dynamic model and experimental validation for motion of a part in a vibratory bowl feeder

In this research, dynamics of a part in a vibratory bowl feeder is studied. So far, studies have been done in two dimensions which is an inaccurate approximation to the 3D part motion. Hence, a new dynamic model is introduced for motion of the part under the effect of base excitation which is moving on or separating from a 3D spiral track. Different scenarios which may occur due to the interaction of the part and the track such as sliding and hopping are predicted. The equations of motion of the part are derived for each scenario and a solution algorithm is presented. The system of equations is solved numerically to obtain the position of the part as a function of time. To validate the proposed dynamic model and the numerical solution, experimental tests are carried out. Good agreement between the results of these methods demonstrates the accuracy of this model. It is observed that the excitation frequency would greatly affect the motion of the part. For low excitation frequencies, the only mechanism involved in the motion of the part is the sliding one. By increasing the excitation frequency, the major driving mechanism changes to hopping.

Globe-LFMC, a global plant water status database for vegetation ecophysiology and wildfire applications

Globe-LFMC is an extensive global database of live fuel moisture content (LFMC) measured from 1,383 sampling sites in 11 countries: Argentina, Australia, China, France, Italy, Senegal, Spain, South Africa, Tunisia, United Kingdom and the United States of America. The database contains 161,717 individual records based on in situ destructive samples used to measure LFMC, representing the amount of water in plant leaves per unit of dry matter. The primary goal of the database is to calibrate and validate remote sensing algorithms used to predict LFMC. However, this database is also relevant for the calibration and validation of dynamic global vegetation models, eco-physiological models of plant water stress as well as understanding the physiological drivers of spatiotemporal variation in LFMC at local, regional and global scales. Globe-LFMC should be useful for studying LFMC trends in response to environmental change and LFMC influence on wildfire occurrence, wildfire behavior, and overall vegetation health.

Experimental study on flame morphologic characteristics of wall attached non-premixed buoyancy driven turbulent flames

This work investigates the effects of the wall on the morphologic characteristics of non-premixed buoyancy driven turbulent flames attached to the wall. Experiments are carried out with rectangular burners having their long side attached to a wall. The investigation is based on dimensional analysis and comprehensive experimental data, including comparison of the flame characteristics of the wall attached flames with free flames. Results show that the non-dimensional flame heights of wall attached flames experience a two-dimensional to three-dimensional transition as free flames do. The critical dimensionless heat release rate for this transition is smaller for the wall attached flames (0.30) than that of the free flames (0.39). The flame height fluctuation of wall attached flames is smaller than that of free flames and decreases with an increase in the nozzle aspect ratio. The ratio of flame thickness (or flame width) to flame height of wall attached flames is smaller than that of free flames. New correlations for flame height, width and thickness of the wall attached flames are proposed based on the mirror-approach of the rectangular source relative to that of a free flame, where the burner perimeter is found to be an appropriate length scale. This work provides important knowledge on the effect of wall on flame characteristics of buoyancy driven turbulent flames, which is essential to the design and risk assessment of the laying of gaseous fuel transportation pipelines in the city and also provides data for validation of computational fluid dynamics (CFD) models.

Optical fibre void fraction detection for liquid metal fast neutron reactors

Detection and characterisation of voids in heavy liquid metals (HLM) is required for next generation nuclear reactor systems. However, its determination presents a challenge owing to their opaque nature and the high temperatures involved. Therefore, tools are needed that can be used to capture local, quantitative information at relevant nuclear operating conditions.In this work, the feasibility of using optical fibre sensors for the measurement of void fractions in liquid metals is presented. Since the functioning of optical probes is usually explained by a crude on-off model, the complexity of both the optical response and the hydrodynamic tip–interface interactions often remain hidden to new users. To clarify this point, well-controlled lab-scale experiments dealing with the response of three concept probe tip geometries are presented. Analysis of the obtained signal transients is used to provide guidelines for effective data processing. To conclusively demonstrate the principle, an optimal prototype system successfully determined the local void fraction and frequency in a pilot-scale reactor using liquid lead bismuth eutectic (LBE) as working fluid.The information obtained by the optical sensor allows for validation of computational fluid dynamics (CFD) models to aid the design of LBE-based nuclear reactors, as well as for other liquid metal–gas systems in general.

Human-based dynamics of mental workload in complicated systems.

As a dynamic system in which different factors affect human performance via dynamic interactions, mental workload needs a dynamic measure to monitor its factors and evidence in a complicated system, an approach that is lacking in the literature. The present study introduces a system dynamics-based model for designing feedback mechanisms related to the mental workload through literature review and content analysis of the previous studies. A human-based archetype of mental workload was detected from the data collection process. The archetype is presented at various stages, including dynamic theory, behavior over time, leverage points and model verification. The real validation of the dynamic model was confirmed in an urban train simulator. The dynamic model can be used to analyze the long-term behavior of the mental workload. Decision-makers can benefit from the developed archetypes in evaluating the dynamic impact of their decisions on accident prevention in the complicated systems.

A Dynamic Model for KUKA KR6 in SPIF Processes

The paper presents the development of a dynamic model for the KUKA KR6 robot during single point incremental forming (SPIF) of metal sheets. The dynamic model of the KUKA KR6 robot is created in MATLAB®-SimMechanics. This dynamic model is necessary to verify that the mechanical structure of this low payload industrial robot of 36 Kg capacity can withstand some specific forces in incremental forming of some low plasticity alloys like Ti6Al4V. In the Centre of Studies and Research for Plastic Deformations of "Lucian Blaga" University of Sibiu, different attempts on single point incremental forming of thin metal sheets have been carried out and some of the studies are based on SPIF using the KUKA KR6-2 industrial robot. Nevertheless, the previous experimental attempts using the KUKA KR 6-2 robot in SPIF processes were realised only on 0.4 mm thick DC04 steel sheets. This material has very good deformability properties and the forces during the process are relatively small. After the dynamic model validation some specific circular trajectories are imposed and the forces that can appear during SPIF process for Ti6Al4V alloy sheets are taken into consideration. After forces analysis, it was concluded that the KUKA KR6 robot can be used in single point incremental forming processes for metal parts requiring greater forming forces.

Static and Dynamic Transmission Error Measurements of Helical Gear Pairs With Various Tooth Modifications

This paper presents a set of motion transmission error data for a family of helical gears having different profile and lead modifications operated under both low-speed (quasi-static) and dynamic conditions. A power circulatory test machine is used along with encoder and accelerometer-based transmission error measurement systems to quantify motion transmission behavior within wide ranges of torque and speed. Results of these experiments indicate that the tooth modifications impact the resultant static and dynamic transmission error amplitudes significantly. A design load is shown to exist for each gear pair of different modifications where static transmission error amplitude is minimum. Forced response curves and waterfall plots are presented to demonstrate that the helical gear pairs tested act linearly with no signs of nonlinear behavior such as tooth contact separations. Furthermore, static and dynamic transmission error amplitudes are observed to be nearly proportional, suggesting that static transmission error can be employed in helical gear dynamic models as the main gear mesh excitation. The data presented here is intended to fill a void in the literature by providing means for validation of load distribution and dynamic models of helical gear pairs.

Impact of Soil Reflectance Variation Correction on Woody Cover Estimation in Kruger National Park Using MODIS Data

Time-series of imagery acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) has previously been used to estimate woody and herbaceous vegetation cover in savannas. However, this is challenging due to the mixture of woody and herbaceous plant functional types with specific contributions to the phenological signal and variations in soil background reflectance signatures observed from satellite. These factors cause variations in the accuracy and precision of woody cover estimates from different modelling approaches and datasets. Here, woody cover is estimated over Kruger National Park (KNP) from the MODIS 16-day composite time-series data using dry season NDVI/SAVI images and applying NDVIsoil determination methods. The woody cover estimates when NDVIsoil was ignored had R² = 0.40, p < 0.01, slope = 1.01, RMSE (root mean square error) = 15.26% and R² = 0.32, p < 0.03, slope = 0.79, RMSE = 16.39% for NDVIpixel and SAVIpixel, respectively, when compared to field plot data of plant functional type fractional cover. The woody cover estimated from the soil determination methods had a slope closer to 1 for both NDVI and SAVI but also a slightly higher RMSE. For a soil-invariant method, RMSE = 19.04% and RMSE = 17.34% were observed for NDVI and SAVI respectively, while for a soil-variant method, RMSE = 18.28% and RMSE = 19.17% were found for NDVI and SAVI. The woody cover estimated from all models had a high correlation and significant relationship with LiDAR/SAR based estimates and a woody cover map produced by Bucini. Woody cover maps are required for vegetation succession monitoring, grazing impact assessment, climate change mitigation and adaptation research and dynamic vegetation model validation.

Dynamic modelling and experimental validation of CO2 removal using hydrophobic membrane contactor with different types of absorbent

In this study, a dynamic model was proposed to simulate and validate the profile of carbon dioxide (CO2) absorption using in-house fabricated mixed matrix membrane (MMM) from membrane gas absorption (MGA) contactors. The flat sheet MMM was fabricated by incorporating TS-530 fumed silica nanoparticles into polyvinylidene fluoride (PVDF) polymer matrix. The membrane surface was coated with low-density polyethylene (LDPE) to enhance membrane hydrophobicity and performance. The performance of the membrane on CO2 absorption was tested in the MGA contactor using different types of liquid absorbent; water, 2-amino-2-methyl-1-propanol (AMP) and dimethylamine (DEA). The mass transfer of CO2 through gas phase, membrane and liquid phase was taken into account in the proposed model. The physical and chemical absorption in liquid phase was also considered during the simulation process. Other than Henry’s constant of CO2 into the absorbent, the solubility of CO2 in the polymeric membrane was also found to have a significant effect on the CO2 absorption. The simulation results were found to be in agreement with the experimental data of CO2 absorption flux.

Dynamic modeling and analysis of a quad horizontal damper system for transient vibration reduction in top loading washing machine

The transient horizontal vibration of top loading washing machine with large capacity has been more important because of the radius of the inner tub in the washing machine increases proportionally. In this paper, we introduce a new vibration reduction technology, namely, a quad horizontal damper system for reduction of the transient horizontal vibration of top loading washing machine. And analyzes the vibration characteristics of a top loading washing machine with a quad horizontal damper system using Newtonian mechanics. For verification and validation of the established dynamic model, the displacement of an actual top loading washing machine are obtained from six laser sensors attached at the upper part and the lower part of outer tub respectively. Optimal design was carried out to ensure sufficient strength and reliability for each component of the horizontal damper. The damping force of the horizontal damper was also optimized so that the horizontal vibration in the transient state of top loading washing machine was reduced by about 35~45 % more than the conventional top loading washing machine and no abnormal noise was generated at high spin speed.

Experimental investigation on multiscale hydrodynamics in a novel gas–Liquid–Solid three phase jet‐Loop reactor

Multiphase flow hydrodynamics in a novel gas–liquid–solid jet‐loop reactor (JLR) were experimentally investigated at the macroscales and mesoscales. The chord length distribution was measured by an optical fiber probe and transformed for bubble size distribution through the maximum entropy method. The impacts of key operating conditions (superficial gas and liquid velocity, solid loading) on hydrodynamics at different axial and radial locations were comprehensively investigated. JLR was found to have good solid suspension ability owing to the internal circulation of bubbles and liquid flow. The gas holdup, axial liquid velocity, and bubble velocity increase with gas velocity, while liquid velocity has little influence on them. Compared with the gas–liquid JLRs, solids decrease the gas holdup and liquid circulation, reduces the bubble velocity and delays the flow development due to the enhanced interaction between bubbles and particles (Stokes number >1). This work also provides a benchmark data for computational fluid dynamics (CFD) model validation. © 2019 American Institute of Chemical Engineers AIChE J, 65: e16537, 2019

Optimization design of the key parameters of McPherson suspension systems using generalized multi-dimension adaptive learning particle swarm optimization

The performance parameters of suspension systems must be properly matched to ensure the handling and stability performance of a vehicle. Based on real vehicle measured data, a parameterized vehicle dynamic model is built, and the validity of the parameterized vehicle dynamic model is verified by comparing simulation results with real vehicle test results. Seven representative steady-state and transient single evaluation indicators of handling and stability of the vehicle are selected. The key parameters of McPherson suspension system, which significantly affects steady-state and transient handling and stability performance, are selected through a sensitivity analysis. Their contribution rates for each single evaluation indicator are calculated based on 81 simulation tests using the parameterized vehicle dynamic model. A comprehensive evaluation indicator system for the whole vehicle is established. This system contains the seven steady-state and transient single handling and stability evaluation indicators that are obtained using a quadratic response surface fitting for the selected key parameters. The comprehensive evaluation indicator system is used to show whether a vehicle has good steady-state and desirable transient responses. Moreover, a generalized multi-dimension adaptive learning particle swarm optimization is proposed to search for the global optimum of the comprehensive evaluation indicator system across the search space with rapid convergence. Optimization results show that a comprehensive handling and stability performance are improved, and simulation results of the parameterized vehicle dynamic model that is modified in accordance with the optimization results verify the improvement of the steady-state steering driving behavior and transient yaw response of the vehicle. In conclusion, the comprehensive evaluation indicator system is feasible, and the generalized multi-dimension adaptive learning particle swarm optimization is effective for the optimization design of the key parameters of the McPherson suspension system.

Local Lagged Adapted Generalized Method of Moments: An Innovative Estimation and Forecasting Approach and its Applications

Abstract In this work, an attempt is made to apply the Local Lagged Adapted Generalized Method of Moments (LLGMM) to estimate state and parameters in stochastic differential dynamic models. The development of LLGMM is motivated by parameter and state estimation problems in continuous-time nonlinear and non-stationary stochastic dynamic model validation problems in biological, chemical, engineering, energy commodity markets, financial, medical, military, physical sciences and social sciences. The byproducts of this innovative approach (LLGMM) are the balance between model specification and model prescription of continuous-time dynamic process and the development of discrete-time interconnected dynamic model of local sample mean and variance statistic process (DTIDMLSMVSP). Moreover, LLGMM is a dynamic non-parametric method. The DTIDMLSMVSP is an alternative approach to the GARCH(1,1) model, and it provides an iterative scheme for updating statistic coefficients in a system of generalized method of moment/observation equations. Furthermore, applications of LLGMM to energy commodities price, U.S. Treasury Bill interest rate and the U.S.–U.K. foreign exchange rate data strongly exhibit its unique role, scope and performance, in particular, in forecasting and confidence-interval problems in applied statistics.