Representative Simulation Model Research Articles

Research and application of SiC _ MOSFETs in DC-DC circuit of new energy electric vehicle

In recent years, with the continuous optimization and improvement of power devices, various types of devices such as SiC _ MOSFETs, IGBTs, and Si _ MOSFETs have emerged in the market. Although the datasheets for these devices provide detailed descriptions of their device structures and electrical characteristics, there is a relative scarcity of specific application scenarios and corresponding simulation experimental data. This paper aims to comprehensively review recent research on the device structures and electrical characteristics of SiC _ MOSFETs, IGBTs, and Si _ MOSFETs. Additionally, we intend to conduct a systematic classification and comparative analysis to evaluate their performance in practical circuit applications. Furthermore, we have utilized MATLAB and Simulink to construct a representative simulation model of a DC-DC Buck-Boost circuit for new energy electric vehicles. Common SiC _ MOSFETs, IGBTs, and Si _ MOSFETs available in the market have been selected, and their parameters have been configured to match those in the simulation circuit. This approach enables us to explore the performance of these components in real-world circuit applications. Subsequently, the performance of these simulated circuits has been rigorously examined in practical scenarios. This comprehensive analysis provides a deeper understanding of the advantages of SiC _ MOSFETs compared to the other two devices and their potential contribution to the future development of electric vehicle technology. We anticipate that this research will drive advancements in electric vehicle technology and contribute to the realization of sustainable mobility.

Failure analysis of the edge-notched beam test on fluid-exposed Berea Sandstone

Injection of fluids during wastewater disposal and geologic carbon sequestration causes induced stress and changes in rock’s elastic and failure properties, such as elastic moduli and fracture toughness. An accurate understanding of such changes in the response requires modeling and analysis of fluid-induced changes in rock’s stress and deformation states for which core-scale mechanical loading tests are often employed. Using experiments and simulations of Single Edge Notched Beam (SENB) test on water-exposed and supercritical (sc) CO_2-exposed Berea sandstones, we quantify the effect of pore fluid on tensile crack propagation, spatial distributions of shear and tensile stresses, and fracture toughness and J-integral properties. We use Digital Image Correlation (DIC) to monitor the changes in local stress and deformation fields during crack initiation and propagation. A representative numerical simulation model of dynamic crack propagation under SENB loading is built using the extended finite element method. Results are analyzed using the stress path analysis to identify shear and tensile stress concentration regions, which provide precursory information for failure events during the test. Stress profiles along and across the growing crack are analyzed and compared with Irwin’s classical solutions to understand the impact of SENB loading. Evolution in stress intensity factor and crack length shows subcritical crack growth prior to Griffith-like failure at the structure scale.

Automatic Detection of Marine Litter: A General Framework to Leverage Synthetic Data

The spatial and temporal coverage of spaceborne optical imaging systems are well suited for automated marine litter monitoring. However, developing machine learning-based detection and identification algorithms requires large amounts of data. Indeed, when it comes to marine debris, ground validated data is scarce. In this study, we propose a general methodology that leverages synthetic data in order to avoid overfitting and generalizes well. The idea is to utilize realistic models of spaceborne optical image acquisition and marine litter to generate large amounts of data to train the machine learning algorithms. These can then be used to detect marine pollution automatically on real satellite images. The main contribution of our study is showing that algorithms trained on simulated data can be successfully transferred to real-life situations. We present the general components of our framework, our modeling of satellites and marine debris and a proof of concept implementation for macro-plastic detection with Sentinel-2 images. In this case study, we generated a large dataset (more than 16,000 pixels of marine debris) composed of seawater, plastic, and wood and trained a Random Forest classifier on it. This classifier, when tested on real satellite images, successfully discriminates marine litter from seawater, thus proving the effectiveness of our approach and paving the way for machine learning-based marine litter detection with even more representative simulation models.

Gastroesophageal Balloon Tamponade Simulation Training with 3D Printed Model Improves Knowledge, Skill, and Confidence.

Gastroesophageal balloon tamponade (BT) tube placement is a life-saving procedure for refractory bleeding from gastroesophageal varices performed by gastroenterologists, intensivists, internists, and emergency medicine physicians. Despite a recognized need for procedural training, no standard curriculum or assessment tools exist. Given the infrequent performance of this procedure, the development of a representative and accessible simulation model would permit hands-on training to practice and maintain proficiency with BT tube placement. To assess BT tube placement performance before and after a novel simulation-based learning module in gastroenterology fellows and faculty. A 16-item knowledge questionnaire and 22-item procedural skill checklist utilizing a novel 3D printed esophagus model were developed to assess participant knowledge, procedural skills, and confidence prior to our simulation-based intervention and again 8-12weeks after. Performance metrics were compared pre- and post-intervention within groups and between participant groups. Fifteen gastroenterology fellows (of 15 eligible; 100%) and 14 gastroenterology faculty (of 29 eligible; 48%) completed training. Fellows demonstrated improvement in knowledge (55% to 79%, p < 0.001) and procedural skill (35% to 57%, p < 0.001) following training. Baseline faculty performance did not differ from fellows' performance and post-intervention showed similar improvement in knowledge (61% to 77%, p = 0.001) and procedural skill (40% to 49%, p = 0.147). Overall satisfaction with training was high in both groups post-intervention and faculty felt more confident teaching fellows. The presented learning module offers a unique, low stakes opportunity for learners to improve skills, gain knowledge, and build confidence in placing BT tubes using a realistic simulation model.

Internal friction angle model of particles

Currently, pressure from industry to streamline processes by creating their simulation models, and thus to gradual digitization is increasing. The essence of representative simulation models of bulk materials is to understand the principles and laws of the real behavior of particles. The aim of this study is therefore to find and quantify the possibilities and principles of how particles can change their position relative to other particles. The possibilities of particle displacements were expressed using their specific trajectories and work ratios, or internal friction angle values. This created a new comprehensive model of the internal friction angle of particles independent of particle size. It enables the interpretation of the determined values of the angles of internal friction of particles and its application in the field of simulations of mass and process models. The model can be used to determine the basic composition of particles in volume and the dominant ways of their mutual displacements.

Numerical analysis of influence of joint inclination on the stability of high rock slope with weak interlayer

In the mountainous area of southwest China, the horizontal layered steep slopes with weak intercalations are widely distributed. The stability of these slopes is often controlled by the weak intercalations and the dominant joint sets. Based on the strength reduction method, a representative numerical simulation model is established in this study, and the ubiquitous-joint model is adopted in which the properties of rock blocks and joints can both be considered, in order to analyze the influence of joint angle on slope stability and potential sliding surface of such slopes. The research results indicate that the joint inclination angle is closely related to both the safety coefficient and the potential sliding range of the slope. With the increase of joint inclination angle, the safety coefficient of the slope decreases, but the downward trend gradually becomes slower. The joint inclination angle also has an obvious influence on the sliding surface range of the horizontal layer slope with weak interlayer. The research results have certain guiding significance in the analysis of failure mechanism, hazard assessment and engineering prevention of this kind of slope.

Shark attacks on offshore streamer cables

In the search for new subsea oil fields, geologists use vessels to tow streamer cables, which collects seismic data. This activity attracts bull sharks to the magnetic streamer fields causing shark attacks and hence losses and delays. This paper discusses how shark attacks on streamer cables can be modelled and simulated in cable design and optimization processes. In order to generate a representative simulation model, a large and authentic bull shark jaw was 3D-scanned. The shark jaw was converted to a CAD-model utilizing reverse engineering applications. Numerical models of the streamer cables, capturing the response with respect to friction properties and failure criteria’s, were benchmarked using quasi-static compression tests. Additionally, dynamic bite and impact simulations replicating the shark attack on streamer cables have been conducted. The physical compression tests and simulations show that the streamer cable FE-models are valid. The results indicate that a shark bite can be sufficient to critically damage the cable, but the bite resilience of the streamer cable is strongly correlated to the shark speed upon impact.

Action-Level Real-Time Network-on-Chip Modeling

To simulate time-constrained operations and scheduling for Network-on-Chip (NoC) systems, we introduce a new set of component specifications at flit level grounded in Action-Level Real-Time DEVS formalism. These models capture the dynamics of NoC systems through action-based behavior under strict execution time intervals. These DEVS-based models are well-suited for development and simulation of asynchronous NoC architectures. This is achieved by extending the DEVS-Suite simulator to support real-time executions of ALRT-DEVS models. Representative simulation models capturing structure and behavior of prototypical Mesh NoC systems are developed. A set of experiments are designed, implemented, executed, and analyzed to show the kind of real-time simulation capabilities that can be achieved for Network-on-Chip systems.

The automotive Order-to-Delivery process: How should it be configured for different markets?

The Order-to-Delivery (OTD) process in the volume automotive sector is important for automakers, dealers and customers. It affects the customer's experience with regard to receiving a vehicle that matches their requested specification in a reasonable time and the costs of the automaker in serving the market. OTD processes share similarities across major volume automakers. They are substantial in scale with typically a very large number of vehicle variants and involve interactions between customers, dealers and the automaker. Additionally, automotive markets are heterogeneous. Some customers have little tolerance to compromising on specification and/or waiting for a vehicle whilst others are more tolerant on one or both attributes. This study examines how the OTD process should be configured for different markets. A representative simulation model is used with designed experiments and an innovative statistical analysis method to study the impact of nine OTD configuration factors in three different markets. The study shows that market attributes have a substantial bearing on the dominant modes of fulfillment, on customer-centric performance metrics and on automaker costs. The findings have strong implications for automakers regarding how they configure their OTD processes for different markets and whether they focus on upstream, pre-assembly factors and/or downstream post-assembly factors. This is the first study to use a comprehensive and detailed OTD process model, incorporating a wide range of configuration factors, and assess a full range of performance metrics in a designed simulation study.

The difference between reported and real-world CO 2 emissions: How much improvement can be expected by WLTP introduction?

The monitoring and reporting of CO2 emissions of light duty vehicles in Europe and other major markets is based on the New European Driving Cycle and the accompanying test protocol. This procedure has been proven non-representative of real world vehicle operation, fuel consumption and CO2 emissions leading to a gap between officially reported emissions and the ones experienced during real world operation. This gap is reported to be increasing with time. To address this issue and improve the certification procedure for pollutant emissions of vehicles over real driving, the new Worldwide Harmonized Light duty vehicle Test Protocol was designed. This new test procedure is expected to provide more realistic emission and fuel consumption results. In this paper a first estimate of the certification-reality gap under the present (2015) conditions is attempted and the impact of the new test procedure is investigated. Tests were performed on three real vehicles over the two cycles which allowed the development of representative simulation models. A detailed simulation matrix was subsequently formulated, taking into account the two tests and expected conditions occurring during real world driving. Results show that for 2013-14 model year European passenger cars the difference in certified and actually emitted CO2 emissions for an average European passenger car reaches up to 40 g CO2/km (~32% higher than certification). WLTP introduction is expected to improve the picture, however a shortfall of about 10-15% between official and real world may remain.

Geant4-GATE Simulation of a Large Plastic Scintillator for Muon Radiography

Envisaging the possibility of using large-area plastic scintillator slabs as robust detectors for high spatial resolution muon radiography, and prior to prototype development, we study expected basic performance by Monte Carlo simulation. We present preliminary results for a scalable square footprint detector unit of ~ 1 m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , defining a representative simulation model volume of 50 cm ×50 cm, with reflective surfaces and a light readout by direct coupling of 4 small PMTs (in a square arrangement) at one face of the scintillator slab. Light detection efficiency is calculated for several light collection configurations, considering different values of surface roughness, reflectivity, optical coupling index and scintillator thickness. Values maximizing photon detection have been identified. The light response function of 2.5-3.5 cm diameter PMTs for the proposed configuration has been determined. A detector intrinsic spatial resolution of the order of 1 cm is estimated for muon interactions at the center region of the detector module, using a simple centroid positioning algorithm (Anger logic).

Iris Metastasis from Small-Cell Lung Cancer

®54-year-old man underwent computed tomography and was suspected of having lung cancer. The patient underwent video-assisted thoracoscopic partial lobectomy and was histopathologically diagnosed with small-cell lung cancer. For the treatment of the residual tumor, including the metastatic mediastinal lymph nodes, he subsequently received chemoradiotherapy combined with chemotherapy (cisplatin and etoposide) and radiotherapy at a total dose of 60 Gy delivered in 30 fractions. The patient was successfully treated and had a complete response. However, at 4 months after surgery, blurred vision was evident in the right eye; a mass measuring 5 mm in size was observed in the right iris using slit lamp microscopy. No abnormalities were found in the ocular fundus, including the retina, and ocular tension. The corrected visual acuity was measured at 0.9 in the visual acuity test using the Landolt ring chart; this corresponded to 18 of 20 in the Snellen chart. The patient was diagnosed with iris metastasis. No other diseases were detected on chest and abdominal computed tomography, head magnetic resonance imaging, and bone scintigraphy. Subsequently, chemotherapy with cisplatin and etoposide was administered. The metastatic tumor exhibited a transient reduction in size but then regrew. Consequently, the patient received radiotherapy with 7-MeV electrons through an anterior port for treatment of the iris metastasis. Because the patient was treated with radiotherapy without computed tomography simulation, for reference, dose distribution curves obtained using a representative radiotherapy simulation model are shown in Fig. 1. Daily fraction size was 2 Gy, 5 days per week, and the total dose was 40 Gy delivered in 20 fractions. A bolus with a 5 mm water-equivalent thickness was used to compensate for the surface dose in the tumor. The overall treatment time was 30 days. The tumor volume decreased rapidly after the initiation of radiotherapy and had completely disappeared by the completion of treatment (Fig. 2). Regarding acute toxicities, the patient had mild radiation keratitis, conjunctivitis, and dermatitis; however, these reactions had all resolved shortly after the completion of radiotherapy.

A review on simulation models for exploration and exploitation of natural gas hydrate

Simulation models have been used widely to help design, operate, control and optimize the processes of exploration and exploitation of natural gas hydrates and been responsible for many of the most important technology breakthroughs. Currently, a rich body of literature exists and is still evolving. This paper presents a critical review of the most influential works that are recognised as representative and important simulation models and links to the techniques commonly used in natural gas hydrate exploration and exploitation. Model background, ideal assumptions and main results are presented. Models are broadly classified into two categories: physically and empirically based models. Models are reviewed with comprehensive, although not exhaustive, publications. The strengths and limitations of the models are discussed. The paper is concluded by outlining open questions and new directions for future work. The review is useful for understanding the innovation process and the current and future status of simulation models on exploration and exploitation of natural gas hydrate and highlights the key aspects of model improvement.

Evaluation of Local Flow Conditions in Jailed Side Branch Lesions Using Computational Fluid Dynamics

Background and ObjectivesLesions of vascular bifurcation and their treatment outcomes have been evaluated by anatomical and physiological methods, such as intravascular ultrasound and fractional flow reserve (FFR). However, local changes in flow dynamics in lesions of bifurcation have not been well evaluated. This study aimed at evaluating changes in the local flow patterns of bifurcation lesions.Materials and MethodsEight (n=8) representative simulation-models were constructed: 1 normal bifurcation, 5 main-branch (MB) stenting models with various side-branch (SB) stenoses (ostial or non-ostial 75% diameter stenosis with 1- or 2-cm lesion lengths, ostial 75% diameter stenosis caused by carina shift), and 2 post-kissing models (no or 50% SB residual stenosis). Pressure, velocity, and wall shear stress (WSS) profiles around the bifurcation sites were investigated using computational fluid dynamics.ResultsPost-stenting models revealed significant pressure drop in the SB (FFR<0.75), excluding the carina shift model (FFR=0.89). In the post-kissing models, there was no significant pressure drop. All post-stenting models revealed eccentric low velocity flow patterns and areas of low WSS, primarily in the lateral wall on distal MB. Post-kissing angioplasty improved pressure drop in the SB but resulted in alteration of flow distribution in the MB. In the carina shift model, kissing ballooning resulted in deteriorated local flow conditions due to increased area of low velocity and WSS.ConclusionThis study suggests that the most commonly used bifurcation intervention strategy may cause local flow disturbances, which may partially explain high restenosis and event rates in patients with bifurcation lesions.

A multidimensional, generalized coupled Markov chain model for surface and subsurface characterization

This paper develops a Markov chain‐based geostatistical model for multidimensional field predictions of the categorical attributes. An efficient conditional probability equation that considers directional asymmetry was derived, and a computational algorithm was devised with numerical code. The developed model was applied to two‐dimensional case studies and compared with the representative conventional sequential indicator simulation (SIS) model. On the basis of engaged comparisons with the SIS model, it was concluded that this new model performs as well as or better than the SIS model, especially for lithologic predictions and structural estimations for the case studies with sparse sampled data, which is more or less realistic. The model was also applied to a three‐dimensional case and validated by its plausible results. It is expected that the developed Markov chain‐based geostatistical model will become a sound option for multidimensional subsurface predictions in cases when the heterogeneities and uncertainties in the media properties are an important issue.

Mass Customization in the Automotive Industry: Comparing Interdealer Trading and Reconfiguration Flexibilities in Order Fulfillment

Mass customization has been viewed as desirable but difficult to achieve in the volume automotive sector. Here we consider flexibility in automotive order fulfillment systems to enhance the ability to satisfy customers with their desired vehicle variants within acceptable delivery lead times. Two types of flexibility are compared in a Virtual‐Build‐to‐Order system—reconfiguration in the planning pipeline and interdealer trading. A representative simulation model is used to investigate the impact of the two types of flexibility across a wide spectrum of product variety levels. The impacts on major stakeholders in the system—the producer, dealers, and customers—are considered. The study shows that both types of flexibilities can bring significant benefits in terms of reductions in lead time and inventory holding. The level of product variety strongly influences the observed effects—an important finding in the mass customization context. Upstream reconfiguration flexibility brings greater benefits than downstream trading flexibility. Reconfiguration tends to dominate trading as a fulfillment mechanism when both are in operation. The findings have implications for the design and management of automotive order fulfillment systems in improving their ability to offer mass customization. The study has relevance for companies in other sectors with high levels of variety that seek to combine efficiency, speed, and flexibility in order fulfillment.

Mass customization in the automotive industry: comparing interdealer trading and reconfiguration flexibilities in order fulfillment

Mass customization has been viewed as desirable but difficult to achieve in the volume automotive sector. Here we consider flexibility in automotive order fulfillment systems to enhance the ability to satisfy customers with their desired vehicle variants within acceptable delivery lead times. Two types of flexibility are compared in a Virtual-Build-to-Order system—reconfiguration in the planning pipeline and interdealer trading. A representative simulation model is used to investigate the impact of the two types of flexibility across a wide spectrum of product variety levels. The impacts on major stakeholders in the system—the producer, dealers, and customers—are considered. The study shows that both types of flexibilities can bring significant benefits in terms of reductions in lead time and inventory holding. The level of product variety strongly influences the observed effects—an important finding in the mass customization context. Upstream reconfiguration flexibility brings greater benefits than downstream trading flexibility. Reconfiguration tends to dominate trading as a fulfillment mechanism when both are in operation. The findings have implications for the design and management of automotive order fulfillment systems in improving their ability to offer mass customization. The study has relevance for companies in other sectors with high levels of variety that seek to combine efficiency, speed, and flexibility in order fulfillment.

Are water simulation models consistent with steady-state and ultrafast vibrational spectroscopy experiments?

Vibrational spectroscopy can provide important information about structure and dynamics in liquids. In the case of liquid water, this is particularly true for isotopically dilute HOD/D 2O and HOD/H 2O systems. Infrared and Raman line shapes for these systems were measured some time ago. Very recently, ultrafast three-pulse vibrational echo experiments have been performed on these systems, which provide new, exciting, and important dynamical benchmarks for liquid water. There has been tremendous theoretical effort expended on the development of classical simulation models for liquid water. These models have been parameterized from experimental structural and thermodynamic measurements. The goal of this paper is to determine if representative simulation models are consistent with steady-state, and especially with these new ultrafast, experiments. Such a comparison provides information about the accuracy of the dynamics of these simulation models. We perform this comparison using theoretical methods developed in previous papers, and calculate the experimental observables directly, without making the Condon and cumulant approximations, and taking into account molecular rotation, vibrational relaxation, and finite excitation pulses. On the whole, the simulation models do remarkably well; perhaps the best overall agreement with experiment comes from the SPC/E model.

Modeling the geomagnetic perturbations produced by ionospheric currents, above and below the ionosphere

This paper briefly surveys the nature of magnetic perturbations at the ground and at low-Earth-orbit (LEO) altitudes produced by ionospheric and geomagnetic-field-aligned currents, with the aid of representative simulation and empirical models. The equatorial electojet, driven by the eastward daytime ionospheric electric field, strongly affects magnetic perturbations near the magnetic equator. Thermospheric winds also influence low-latitude ionospheric currents, and create significant east–west magnetic perturbations at lower LEO altitudes. At midlatitudes, currents flow not only within the ionosphere but also along geomagnetic field lines above the ionosphere. The latter can produe significant large-scale magnetic perturbations above the ionosphere over large regions of space. The largest magnetic perturbations are produced by electric currents in the auroral zones and the geomagnetic-field-aligned currents that connect the ionosphere with the outer magnetosphere. Above the ionosphere, the high-latitude magnetic perturbations tend to be dominated by toroidal magnetic perturbation fields associated with the field-aligned currents. LEO observations of magnetic perturbations can provide valuable information about the drivers of the ionospheric dynamo, the state of the magnetosphere, and the transfer of energy between the magnetosphere and the ionosphere.

The influence of simulated shadelight and daylight on growth, development and photosynthesis of Pinus radiata, Agathis australis and Dacrydium cupressinum

Abstract. Juvenile seedlings, micropropagated plantlets, and adult rooted cuttings of Pinus radiata, together with seedlings of Agathis australis and Dacrydium cupressinum, were grown under either high (670/μmol m−2 s−1) or low (200 μmol m−2 s−1) photosynthetic photon flux density (PPFD) and, at low PPFD, under three red:far‐red (R/FR) conditions, approximately simulating canopy shadelight, daylight and one intermediate value. In all types of P. radiata, a shade‐intolerant species, stem height and diameter, stem and needle dry weight, and apical dominance were markedly increased by a reduction in R:FR ratio while fascicle density was decreased. In contrast, these increases were considerably less for the shade‐tolerant D. cupressinum and moderately tolerant A. australis. With the exception of the P. radiata seedlings, height growth was greatest in all species under high compared to low PPFD for daylight R:FR ratio conditions. Total shoot (or plant) dry weight was increased approximately two‐fold in all species and types by the higher PPFD. Shoot extension rates were negatively correlated with calculated phytochrome photoequilibrium with P. radiata, the most shade‐intolerant species, having the highest change in rate per unit change in photoequilibrium (i.e. very responsive), and D. cupressinum, the most shade tolerant species evaluated, having the smallest change (i.e. largely unresponsive). Within the spectral quality treatments at low PPFD, it is suggested that higher rates of dry matter accumulation under the low R:FR ratio were the result of reduced mutual shading of adjacent leaves as a consequence of photomorphogenically‐controlled internode lengths rather than of enhanced photosynthesis per se. The significance of the results is discussed in relation to planting stock management in nurseries, the management of forest canopies for understorey seedling growth, and to the construction of representative growth simulation models. Consequences for controlled environment lighting are also considered.