Validation Of Simulation Model Research Articles

Lithium-Ion Battery Thermal Runaway: Experimental Analysis of Particle Deposition in Battery Module Environment

In this paper, a novel experimental setup to quantify the particle deposition during a lithium-ion battery thermal runaway (TR) is proposed. The setup integrates a single prismatic battery cell into an environment representing similar conditions as found for battery modules in battery packs of electric vehicles. In total, 86 weighing plates, positioned within the flow path of the vented gas and particles, can be individually removed from the setup in order to determine the spatial mass distribution of the deposited particles. Two proof-of-concept experiments with different distances between cell vent and module cover are performed. The particle deposition on the weighing plates as well as the particle size distribution of the deposited particles are found to be dependent on the distance between cell vent and cover. In addition, the specific heat capacity of the deposited particles as well as the jelly roll remains are analyzed. Its temperature dependency is found to be comparable for both ejected particles and jelly roll remains. The results of this study help researches and engineers to gain further insights into the particle ejection process during TR. By implementing certain suggested improvements, the proposed experimental setup may be used in the future to provide necessary data for simulation model validation. Therefore, this study contributes to the improvement of battery pack design and safety.

Validation of a synthetic simulation model of endoscopic rectus sheath plication.

Literature reviews outline minimally invasive approaches for abdominal diastasis in patients without skin excess. However, few surgeons are trained in endoscopic rectus sheath plication, and no simulated training programs exist for this method. This study aimed to develop and validate a synthetic simulation model for the training of skills in this approach under the Messick validity framework. A cross-sectional study was carried out to assess the participants' previous level of laparoscopic/endoscopic skills by a questionnaire. Participants performed an endoscopic plication on the model and their performance was evaluated by one blinded observer using the global rating scale OSATS and a procedure specific checklist (PSC) scale. A 5-level Likert survey was applied to 5 experts and 4 plastic surgeons to assess Face and Content validity. Fifteen non-experts and 5 experts in abdominal wall endoscopic surgery were recruited. A median OSATS score [25 (range 24-25) vs 14 (range 5-22); p < 0.05 of maximum 25 points] and a median PSC score [11 (range 10-11) vs 8 (range 3-10); p < 0.05 of maximum 11 points] was significantly higher for experts compared with nonexperts. All experts agreed or strongly agreed that the model simulates a real scenario of endoscopic plication of the rectus sheath. Our simulation model met all validation criteria outlined in the Messick framework, demonstrating its ability to differentiate between experts and non-experts based on their baseline endoscopic surgical skills. This model stands as a valuable tool for evaluating skills in endoscopic rectus sheath plication.

Dynamic Characteristics of Magnetorheological Mounted Metal Rubber Structures Under Multi-physics Coupling Conditions

To accurately predict the dynamic characteristics of MR mounting, the nonlinear electromagnetic coupling law between MR liquid and soft magnetic material and the solid-liquid interaction, the electromagnetic coupling and fluid-structure coupling mathematical models and numerical simulation models of MR mounting are established. Through the magnetorheological mounting test, the simulation results are compared with the experimental results, and the validity of the numerical simulation model is verified. On this basis, the distribution effect of electromagnetic coupling in a magnetic circuit is analyzed. According to the Bingham model, the variation rule of magnetorheological fluid damping force was deduced. The magnetic field simulation results are introduced into the fluid model and the fluid-solid model, and the fluid-solid coupling effect of the numerical model of magnetorheological mounting is calculated. The dynamic and static characteristics of magnetorheological mounting under different current excitation conditions are simulated. It provides the basis for designing and simulating multi-physical field simulation of MR mounting.

Remaining useful lifetime prediction for milling blades using a fused data prediction model (FDPM)

AbstractIn various industry sectors, predicting the real-life availability of milling applications poses a significant challenge. This challenge arises from the need to prevent inefficient blade resource utilization and the risk of machine breakdowns due to natural wear. To ensure timely and accurate adjustments to milling processes based on the machine's cutting blade condition without disrupting ongoing production, we introduce the Fused Data Prediction Model (FDPM), a novel temporal hybrid prediction model. The FDPM combines the static and dynamic features of the machines to generate simulated outputs, including average cutting force, material removal rate, and peripheral milling machine torque. These outputs are correlated with real blade wear measurements, creating a simulation model that provides insights into predicting the wear progression in the machine when associated with real machine operational parameters. The FDPM also considers data preprocessing, reducing the dimensional space to an advanced recurrent neural network prediction algorithm for forecasting blade wear levels in milling. The validation of the physics-based simulation model indicates the highest fidelity in replicating wear progression with the average cutting force variable, demonstrating an average relative error of 2.38% when compared to the measured mean of rake wear during the milling cycle. These findings illustrate the effectiveness of the FDPM approach, showcasing an impressive prediction accuracy exceeding 93% when the model is trained with only 50% of the available data. These results highlight the potential of the FDPM model as a robust and versatile method for assessing wear levels in milling operations precisely, without disrupting ongoing production.

Model predictive control for thermal comfort and energy optimization of an air handling unit system in airport terminals using occupant feedback

The dynamic fluctuations in occupant flow within airport terminals contribute to delays in the system's response under traditional feedback control. This imbalance between supply and demand can result in discomfort and unnecessary energy consumption. While Occupant-Based Model Predictive Control (OBMPC) has gained research interest as it leverages occupant forecasts to enhance control performance, there is limited knowledge regarding its application in the air-conditioning systems of airport terminals, mainly due to the intricate dynamics of occupant flow in terminal buildings. In this study, we proposed a model predictive control strategy based on dynamic occupant flow with the goal of fast responding to occupant flow and reducing energy consumption. We integrated mathematical formulas and the Anylogic simulation software to predict occupant variations in the baggage claim hall. The model predictive control strategy of the air conditioning system was proposed with the predicted occupant flow. The proposed strategy was evaluated throughout the whole cooling season in the validated simulation model of the air handling unit system of the baggage claim hall at an airport terminal. The results demonstrated that the proposed strategy could effectively respond to variations in occupancy and achieve 10% energy savings throughout the entire cooling season, compared to conventional feedback control. Our work presents a viable solution to address system regulation lag and reduce energy consumption without jeopardizing thermal comfort.

Optimization of all-polymer/Sb2Se3 tandem solar cells for enhanced efficiency: a comprehensive TCAD modeling approach

Abstract This paper introduces a novel tandem configuration, utilizing an all-thin film all-polymer solar cell (all-PSC) with a wide bandgap of 1.76 eV for the front cell and Sb2Se3 with a narrow bandgap of 1.2 eV for the bottom cell. The design of this tandem is performed by comprehensive optoelectronic TCAD tools, essential for optimizing parameters across multiple layers to reach maximum power conversion efficiency (PCE). Experimental validation of models is conducted through calibration and validation against fabricated reference all-polymer and Sb2Se3 solar cells, yielding calibrated PCEs of approximately 10.1% and 10.5%, respectively. Subsequently, validated simulation models for both top and rear cells are utilized to design a 2-T all-polymer/Sb2Se3 tandem cell, which initially achieves a PCE of 10.91%. Through systematic optimization steps, including interface engineering and homojunction structure design, a remarkable PCE of 24.24% is achieved at the current matching point, showcasing the potential of our proposed tandem solar cell design. This study represents a significant advancement in the field of thin-film tandem solar cells, offering promising avenues for efficient and cost-effective photovoltaic technologies, particularly in applications requiring flexibility.

A Monte Carlo simulation study for designing collimators for a CZT-based spent nuclear fuel characterization system

As an attempt to develop a spent nuclear fuel characterization system that can acquire both high-resolution gamma-ray energy spectrum and neutron flux simultaneously at multiple positions around the spent nuclear fuel assembly and provide more information compared to conventional equipment, simulation study was conducted to design a collimator around a gamma-ray detector to obtain high-resolution gamma-ray spectra in a high-flux gamma-ray environment. The ORIGEN depletion code was used to evaluate the source terms of spent nuclear fuel, and MCNP 6.2, the Monte Carlo simulation code, was used to simulate the detector response. Considering the realistic operating conditions of Korea's pressurized light water reactor, the source term for the ACE7 17×17 nuclear fuel assembly was derived under the conditions of initial enrichment ranging from 3 to 5%, burnup ranging from 30 to 60 GWd/MTU, and maximum cooling time of 30 years. MCNP 6.2, the Monte Carlo simulation code, was used to design a spent nuclear fuel characterization system using a CZT detector as a gamma-ray detector to obtain a high-resolution gamma-ray energy spectrum. In particular, the research focused on designing collimators to be used in high-flux radiation environments, such as spent nuclear fuel inspection, with CZT detectors. A simulation model of the CZT detector to be installed internally was made and the validity of the detector simulation model was confirmed by comparing simulation results with the measurement experiment results. Finally, the response of the CZT detector was calculated by changing various setting parameters of the collimator. By comparing the calculated detector response with the design standard count rate, the design of a collimator that can utilize the CZT detector in a spent nuclear fuel inspection environment was derived.

Repair of Inferior Alveolar Nerve in Orthognathic Surgery Simulator (RIANOS): A Novel, Open-Source, Combined 3D Printed, and Ex-Vivo Chicken Sciatic Nerve Training Model

Study Design Face and content validation of a surgical simulation model. Objective Accidental transection of the inferior alveolar nerve (IAN) during bilateral sagittal split osteotomies (BSSO) has a reported incidence of up to 7%, determining important sensory disturbances in patients. Proper repair demands the need of microsurgical anastomosis skills. No previous training models have been described to simulate this. Therefore, we present a validated simulation model for intraoral repair of transected IAN. Methods A CT scan of an orthognathic surgery patient was modified and a 3D model of a mandible with BSSO was printed. Chicken thigh anatomy was reviewed, and 2.5 mm sciatic nerves were dissected and mounted in the model. In order to simulate intraoral work depth, it was put inside a dental phantom or medical glove box. The model was tested by a group of experts (n = 12), simulating a transected IAN repair inside the mouth with both loupes and a double visor surgical training microscope. A survey was conducted to assess Face and Content validity. Results The model was named RIANOS after Repair of Inferior Alveolar Nerve in Orthognathic Surgery Simulator. The printing cost of each model was approximately US$3 and the design file is open-source and available for download. All experts “Strongly Agreed” that the model was useful for training inferior alveolar nerve microsurgical repair and would consider implementing it with their residents. Conclusions We developed a low cost, reproducible, open-source simulator for IAN injury repair training during BSSO. Face and Content validity was achieved through evaluation by a group of experts.

Advanced hemodynamics for prognostication in heart failure: the pursuit of the patient-specific tipping point.

Objective tools to define the optimal time for referral for advanced therapies and to help guide escalation and de-escalation of support can improve management decisions and outcomes for patients with advanced heart failure. The current parameters have variable prognostic potential depending on the patient population being studied and often have arbitrary thresholds. Here, a mathematical and physiological framework to define the patient-specific tipping point of myocardial energetics is defined. A novel hemodynamic parameter known as the myocardial performance score (MPS), a marker of power and efficiency, is introduced that allows for the objective assessment of the physiological tipping point. The performance of the MPS and other advanced hemodynamic parameters including aortic pulsatility index (API) and cardiac power output (CPO) in predicting myocardial energetics and the overall myocardial performance was evaluated using a validated computer simulation model of heart failure (Harvi) as well as a proof-of-concept clinical validation using a cohort of the Society for Cardiovascular Angiography and Interventions (SCAI) Stage C cardiogenic shock patients. Approximately 1010 discrete heart failure scenarios were modeled. API strongly correlated with the left ventricular coupling ratio (R2 = 0.81) and the strength of association became even stronger under loaded conditions where pulmonary capillary wedge pressure (PCWP) was >20 mmHg (R2 = 0.94). Under loaded conditions, there is a strong logarithmic relationship between MPS and mechanical efficiency (R2 = 0.93) with a precipitous rise in potential energy (PE) and drop in mechanical efficiency with an MPS <0.5. An MPS <0.5 was able to predict a CPO <0.6 W and coupling ratio of <0.7 with sensitivity (Sn) of 87%, specificity (Sp) of 91%, positive predictive value of 81%, and negative predictive value of 94%. In a cohort of 224 patients with SCAI Stage C shock requiring milrinone initiation, a baseline MPS score of <0.5 was associated with a 35% event rate of the composite endpoint of death, left ventricular assist device, or transplant at 30 days compared with 3% for those with an MPS >1 (p < 0.001). Patients who were able to augment their MPS to >1 after milrinone infusion had a lower event rate than those with insufficient reserve (40% vs. 16%, p = 0.01). The MPS, which defines the patient-specific power-to-efficiency ratio and is inversely proportional to PE, represents an objective assessment of the myocardial energetic state of a patient and can be used to define the physiological tipping point for patients with advanced heart failure.

Development and Validation of a Dynamic Simulation Model for Water Storage Heating Systems Powered by Electric Boilers in Elementary Schools

Development and Validation of a Dynamic Simulation Model for Water Storage Heating Systems Powered by Electric Boilers in Elementary Schools

Developing a validated simulation model of micro-zonal air-conditioning to evaluate thermal comfort parameters

ABSTRACT Micro-Zonal Occupant-Centric Control (MZOCC) helps in reducing building energy consumption by conditioning only the occupied regions in a room. For this, MZOCC divides a large room such as open-plan offices into virtual micro-zones to allow independent diffuser level control. But, unplanned MZOCC can lead to heavy thermal gradients and deflection of air jets, leading to thermal discomfort. To evaluate thermal comfort at different regions of a room under MZOCC, there is a need to accurately model parameters of thermal comfort. Field studies, exploring the transient variations in air temperature, humidity and velocity at different regions of the room due to MZOCC, are limited. At the same time, developing validated simulation models or digital twins using experimental data helps in exploring micro-zonal strategies to arrive at the best strategy. The aim of this study is to create a digital twin of an open-plan office and model the parameters required to estimate thermal comfort. This study senses transient variations in air temperature, velocity and humidity using a wireless sensor network and develops a computational fluid dynamic (CFD) model that can accurately model the sensed transient variations. Field data, constituting external surface temperatures captured using thermal images, variations in air-conditioning control strategy, dynamic occupancy and location, are periodically updated in the digital twin. The CFD model accurately predicts the trends in variations in indoor temperature, velocity and humidity at different regions of the room. The developed digital twin can be used in future studies to evaluate thermal comfort and plan MZOCC control strategies.

The variability in nociceptive flexion reflex threshold measurement is mostly caused by probabilistic effects of the estimation algorithms: a simulation study

Objectives The nociceptive flexion reflex (NFR) and its threshold are frequently used to investigate spinal nociception in humans. Since this threshold (NFRT) is a probabilistic measure, specific algorithms are used for NFRT estimation based on the stochastic occurrence of reflexes at different stimulus intensities. We used a validated simulation model of the NFR to investigate the amount of NFRT measurement variability induced by different estimation algorithms in a steady setting of reduced external influences. Methods We simulated the behavior of different estimation algorithms in subjects with an artificially steady baseline NFRT variability (standard deviation: 0 mA) or low baseline NFRT variability (standard deviation: 0.156 mA), equaling a quiet experimental setting. The obtained data were analyzed for NFRT measurement variability caused by the algorithms compared to the baseline variability reflecting other physiological influences. Results The standard deviation of the NFRT estimated by the different algorithms ranged between 0.381 and 3.464 mA with 96.8% to 99.6% of the measurement variability attributed to the algorithm used. Out of the investigated algorithms the dynamic staircase algorithm was most precise. Conclusion The NFRT measurement variability observed during quiet and steady experimental sessions is mostly caused by the properties of the estimation algorithms, due to the probabilistic nature of the reflex occurrence. Our results give reference for choosing the optimal estimation algorithm to improve measurement precision.

Double-Skin Facades for Thermal Comfort and Energy Efficiency in Mediterranean Climate Buildings: Rehabilitating Vulnerable Neighbourhoods

The ongoing global energy crisis in Europe has intensified energy poverty in vulnerable households, prompting a critical examination of passive retrofit strategies for improving the habitability of obsolete social housing in southern Europe from the 1960s. Given the Mediterranean climate’s characteristics (hot summers and mild winters), these buildings possess low thermal resistance envelopes designed for heat dissipation in summer but contribute to elevated heating demands in colder months. In response to the pressing need for solutions that strike a balance between reducing energy demand and ensuring year-round comfort, this research explores diverse approaches. Drawing insights from built prototypes in Colombia and Hungary and utilizing a validated simulation model in Seville, Spain, this study investigates the feasibility of implementing a double-skin envelope on building facades and assesses the impact of thermal insulation in the air chamber. So, the research specifically aims to find an equilibrium between lowering energy demand and maintaining adequate comfort conditions, concentrating on the renovation of obsolete social housing with envelopes featuring low thermal resistance in the Mediterranean climate. Results indicate that, due to the poor thermal envelope, the influence of thermal insulation on comfort conditions and energy savings outweighs that of the double skin. Consequently, the emphasis of renovation projects for this climate should not solely concentrate on passive cooling strategies but should strive to achieve a positive balance in comfort conditions throughout the year, encompassing both warm and cold months.

Effects of Thermal-Moisture Coupled Field on Delamination Behavior of Electronic Packaging

Abstract Delamination failure is one of the most prevalent and serious reliability issues in micro-electronic packaging. To understand this phenomenon further, this study constructs an experimental test system consisting of a double cantilever beam (DCB) fixture, an MTS-Acumen microforce tester, and a temperature and humidity controller. The system is employed to investigate the effects of coupled moisture-thermal loading on the critical strain energy release rate (SERR) at the epoxy molding compound (EMC)/Cu leadframe (LF) interface of a very thin quad flat no-lead package (WQFN) assembly. A three-dimensional computational model with hygro-thermal loading conditions is developed to evaluate the moisture diffusion, thermal stress, and integrated stress of a multichip WQFN package under typical processing conditions and precondition tests. The validated simulation model is then applied with the virtual crack closure technique (VCCT) to investigate the fracture behavior at the EMC/Cu LF interface in the WQFN package. The effects of three design parameters on the SERR performance of the package are identified through a parametric analysis. Finally, a Genetic Algorithm (GA) optimization method is employed to examine the effects of the main structural design parameters of the WQFN package on its delamination reliability. The results are used to determine the optimal packaging design that minimizes the SERR and hence enhances the package reliability.

Probabilistic Validation: Computational Platform and Application to Fire Probabilistic Risk Assessment of Nuclear Power Plants

Abstract Recently, there has been an increasing use of advanced modeling and simulation in the nuclear domain across academia, industry, and regulatory agencies to improve the realism in capturing complex and highly spatiotemporal phenomena within the probabilistic risk assessment (PRA) of existing nuclear power plants (NPPs). Advanced modeling and simulation have also been used to accelerate the risk-informed design, licensing, and operationalization of advanced nuclear reactors. Validation of simulation models traditionally relies on empirical validation approaches which require enough validation data. Such validation data are, however, usually costly to obtain in the contexts of the nuclear industry. To overcome this challenge and to effectively support the use of simulation models in PRA and risk-informed decision-making applications, a systematic and scientifically justifiable validation methodology, namely, the probabilistic validation (PV) methodology, has been developed. This methodology leverages uncertainty analysis to support the validity assessment of the simulation prediction. The theoretical foundation and methodological platform of the PV methodology have been reported in the first paper of this two-part series. The purpose of this second paper is to computationalize the PV methodology, embedded in an integrated PRA framework, and apply it for a hierarchical fire simulation model used in NPP Fire PRA.

Incorporating uncertainty into the validation of automotive crash simulation models for component analysis

The design and development of crashworthy vehicles depend increasingly on credible crash simulation results. This credibility requires a careful process of verification and validation (V&V). The former relates to assessing the correctness of the calculation while the latter relates to the appropriateness of the physical and numerical test results. In this context, various sources of uncertainty exist in crash tests as well as in simulation models, which can influence the validation outcomes. Hence, it is essential to study statistical validation approaches for crash applications. In this paper, we elaborate on two important aspects of validation for crash simulation models: quantification of the credibility of simulation models, and consideration of uncertainties in the validation. Limited and noisy experimental data, typical in crash applications, impose a challenge on the investigation of validation approaches. To address these challenges, we use synthetic experimental results in our study. A crash-box model is validated using the V&V20-2009 validation standard. Two case studies are considered. The first case study aims to show the application of the V&V20 approach to a crash problem. The second case is a more complex scenario and aims to explore the impact of different experimental factors, such as experimental noise, hidden uncertainties, and the number of experiments on the validation results. In the end, we examine how underlying assumptions in the validation approach affect the conservativity of the validation results.

Investigation of the technical potential of a hydrogen powered phosphoric acid fuel cell (PAFC) for CHP

Due to the fluctuating feed-in of renewable energies, controllable power plants such as highly efficient CHP plants (combined heat and power) will continue to be required to cover the residual load. Gas engines and turbines currently dominate the natural gas-based CHP market due to their low investment costs and acceptable electrical efficiency. In the event of a future fuel switch due to the energy transition from natural gas to hydrogen, fuel cell systems are becoming increasingly important due to their very high efficiency and improved dynamics in hydrogen operation and can therefore represent an alternative to gas engines and turbines. In addition to a possible fuel switch, good dynamic and full heat utilization represents an additional challenge for CHP systems. Therefore, this study aims to investigate the influence of a fuel switch from natural gas to hydrogen on the operation of a fuel cell (PAFC) in terms of efficiency, heat utilization and dynamics. It was shown that the electrical efficiency of the hydrogen-operated PAFC is significantly higher than in natural gas operation due to the omitted reformer and the associated reformer losses. In hydrogen operation, there is also no limitation of the dynamics by the reformer. Furthermore, in hydrogen operation there is a more favorable ratio of high-temperature to low-temperature heat, which facilitates the use of heat. Detailed and validated simulation models in Aspen Plus are used as the basis for this investigation.

Virological, serological and clinical outcomes in chronic hepatitis B virus infection: development and validation of the HEPA-B simulation model

ObjectivesDetailed simulation models are needed to assess strategies for prevention and treatment of hepatitis B virus (HBV) infection, the world’s leading cause of liver disease. We sought to develop and...

Tiltrotor Simulations with Coupled Flight Dynamics, State-Space Aeromechanics, and Aeroacoustics

This article describes the development, implementation, and validation of a generic tilt-rotor simulation model with coupled flight dynamics, state-variable aeromechanics, and aeroacoustics. A major novelty of this work lies in the integration of the flight dynamics with a state-space free-vortex wake code that adopts a near-wake vortex-lattice model. This way, the flight dynamics are augmented by the vortex wake dynamics so that the coupled flight and wake dynamics are self-contained and inherently linearizable. The model is implemented for a Bell XV-15 tiltrotor and validated against U. S. Army/NASA XV-15 flight-test data and other data in the literature. Flight control design is performed to provide desired stability, performance, and handling-quality properties and to allow for a fully autonomous transition between hover in helicopter mode and highspeed flight in aircraft mode. The simulation model has clear applications in the development and testing of advanced flight control laws, aeromechanics analysis, and the prediction of aerodynamically generated noise in generalized maneuvering flight.

VALIDATION OF COMPUTER SIMULATION OF COMPLEX THERMAL TRANSPORT PROBLEMS: A TRIBUTE TO PROFESSOR DARRELL PEPPER

An important consideration in mathematical modeling and numerical simulation is that of validation of the models. This is particularly critical in thermal systems and processes because of the simplifications and idealizations usually needed to make the problem amenable to a solution, lack of accurate material property data, combined mechanisms, uncertainty in boundary conditions, and other complexities in the process. Modeling is needed for a basic understanding of the processes involved, as well as for providing accurate inputs for system design, control, and optimization. However, it is important to ensure that the numerical code performs satisfactorily for the chosen method and that the model is an accurate representation of the physical problem. These aspects are sometimes referred to as verification and validation, respectively, or simply as validation of the mathematical/numerical model employed. Unless the models are satisfactorily validated and the accuracy of the predictions established, the models cannot be used as basis for design and for choosing operating conditions to obtain desired system or product characteristics. Validation of the models is based on a consideration of the physical behavior of the results obtained, elimination of the effects of arbitrary parameters like grid and time step, comparisons with available analytical or numerical results for similar problems, and comparisons with experimental results on a physical model or a prototype. This paper considers some of the major considerations involved in validation of numerical simulation models for complex thermal problems. A few examples of practical problems are also presented. This topic is chosen because it was of particular interest to Professor Darrell Pepper and the author has had several interactions with him on complex thermal problems.