Simulator Results Research Articles

Design, fabrication, and performance analysis of a silicon solar cell integrated transparent antenna for wireless communications

The solar cell integrated transparent antenna will serve the purpose of power generation as well as an antenna for satellites and can act as an asset to expand the possibilities of green technology. The goal is to enhance antenna characteristics without hampering solar cell performance. In this work, a super solar integrated optically transparent microstrip patch antenna has been studied using CST Microwave Studio along with Lumerical FDTD and DEVICE solutions. The optically transparent antenna has a Soda-lime glass substrate, with Indium Tin Oxide patch and ground plane. The fabricated antenna is integrated with a 25 × 40 mm2 thin-film silicon solar cell via epoxy resin. UV–Vis spectroscopy results revealed more than 90% transmissivity over a significant visible wavelength range. It has an operational bandwidth of 80 MHz (@5.48 GHz) and solar simulator results indicate that the photovoltaic performance of the proposed device is similar to that of a standalone solar cell.

Gas kick dynamic circulation in MPD operations with water based drilling fluid: Maximum casing pressure modeling and validation

The use of water-based drilling fluids enables the rapid detection of a gas influx by pit gain monitoring due to the low solubility of gases in the aqueous medium. Moreover, as the influx remains as a free gas, it undergoes a process of expansion the further it rises through the well, changing the pressure profiles and producing a pressure peak when it reaches the surface. Therefore, the gas influx must be controlled appropriately. Otherwise, the maximum pressure experienced during the kick circulation may exceed the safety limits of surface equipment, placing the operation and the rig crew in a hazardous situation. The Managed Pressure Drilling (MPD) technique allows for a more precise detection and control of the influx while retaining the ability to circulate dynamically small volumes of gas kick through the riser, minimizing the risks involved and the non-productive time (NPT). However, the decision of when to apply dynamic or conventional circulation techniques must be considered carefully, taking into account factors such as predictions of pressure peaks, as well as intensity and volume of the kick. In this way, it is paramount that the maximum pressure during the circulation be estimated before the operation begins to ensure that the decision is made correctly. This paper presents the results of a gas kick circulation simulator specifically developed to predict pressure peaks. This simulator uses a mathematical model based on algebraic equations whose solution requires low computational effort and, therefore, regarding gas kick incidents, is an interesting tool that can aid in guiding decision-making. The results of pressure peaks were successfully validated by employing literature data, experimental drilling setup runs and simulations performed in a commercial software largely consolidated in the petroleum industry: Drillbench.

Subthreshold Drain Current Model of Cylindrical Gate All‐Around Junctionless Transistor With Three Different Gate Materials

ABSTRACTA novel subthreshold drain current model has been developed for a cylindrical gate all‐around junctionless transistor with three different gate materials. The proposed device is built with three gate regions of different work functions that effectively reduce the short‐channel effects caused by quantum mechanical effects. The drain current equation is solved for all three operating regions to investigate the device switching characteristics and minimize the drain‐induced barrier lowering (DIBL), velocity saturation, mobility degradation, and tunneling. It is understood that the triple material gate structure enhances the transport efficiency of the device. The proposed analytical model is validated by comparison with Sentaurus TCAD numerical simulator results and good agreement is found to be achieved.

Construction and assessment of a fire risk index system for typical grasslands in Xinjiang, China

BackgroundFire hazards have a substantial impact on grassland ecosystems, and they are becoming more frequent and widespread because of global changes and human activities. However, there is still a lack of a widely accepted or practical method to evaluate grassland fire risk. In our study of typical grasslands in northern Xinjiang, we selected 18 evaluation indicators for grassland fires from three aspects of hazard, exposure, and vulnerability. Employing the analytic hierarchy process, weighted comprehensive evaluation method, and standard deviation classification, we determined the fire risk level thresholds, aiming to develop efficient and precise methods for assessing grassland fire risks, and ultimately created a grid-based map of grassland fire risk levels.ResultsThe risk level of grassland fires is determined by the combined spatial heterogeneity of fire-causing factors’ hazard and fire hazard-bearing bodies’ vulnerability and exposure. The hazard of grassland fire and fire hazard-bearing bodies’ vulnerability and exposure are dominated by medium level and medium–low level. Most areas of grassland fire risk levels are medium–low, medium, or medium–high risk, with few areas being high risk or low risk. The grassland fire risk exhibits a spatial distribution characterized by higher risks in the western and lower in the eastern; high and medium–high risk areas are primarily distributed in the western and some northeastern regions of the study area. The simulate result effectively represents the spatial distribution of grassland fire in the research area.ConclusionWe established a grassland fire risk index system and model, creating a spatial distribution map of grassland fire risk levels based on grid. Few grassland areas have fire risks and show a patchy distribution. The results generally reflect the spatial distribution pattern of grassland fire risks in the study area. This research provides technical support for scientifically formulating local grassland fire disaster prevention and relief strategies.

Mathematical modeling for the production performance of cyclic multi-thermal fluid stimulation process in layered heavy oil reservoirs

Multi-thermal fluid (MTF), with a unique thermophysical characteristics, has been widely applied in the enhanced heavy oil recovery processes. Especially for the layered heavy oil reservoirs, MTF shows more attractive than the conventional saturated steam. In this study, we propose an improved mathematical model for the production performance of cyclic MTF stimulation process in layered heavy oil reservoirs. In this model, based on a three-zone assumption, we first derive a productivity model for the thermal-fluids huff-n-puff process in layered heavy oil reservoirs. Thereafter, considering the typical EOR mechanisms of non-condensable gases in MTF, the viscosity reduction effect caused by CO2 dissolution and the effect of formation energy supplement caused by N2 are mathematically described. Simultaneously, because of the nonlinear temperature spreading behavior in the formation, an MTFs flooding experiment is also performed to characterize the effect. Meanwhile, a heating radius model with the consideration of steam overlap effect is also involved in our model. Then, the calculation results are compared against the results of a commercial simulator to confirm the accuracy, while a sensitivity analysis on the reservoir and operation parameters is performed. This paper provides a quick estimation approach for the productivity of cyclic MTF stimulation process in layered heavy oil reservoirs.

Adiabatic expansion cooling of antihydrogen

Magnetically trapped antihydrogen atoms can be cooled by expanding the volume of the trap in which they are confined. We report a proof-of-principle experiment in which antiatoms are deliberately released from expanded and static traps. Antiatoms escape at an average trap depth of 0.08±0.01K (statistical errors only) from the expanded trap while they escape at average depths of 0.22±0.01 and 0.17±0.01K from two different static traps. (We employ temperature-equivalent energy units.) Detailed simulations qualitatively agree with the escape times measured in the experiment and show a decrease of 38% (statistical error<0.2%) in the mean energy of the population after the trap expansion without significantly increasing antiatom loss compared to typical static confinement protocols. This change is bracketed by the predictions of one-dimensional and three-dimensional semianalytic adiabatic expansion models. These experimental, simulational, and model results are consistent with obtaining an adiabatically cooled population of antihydrogen atoms that partially exchanged energy between axial and transverse degrees of freedom during the trap expansion. This result is important for future antihydrogen gravitational experiments which rely on adiabatic cooling, and it will enable antihydrogen cooling beyond the fundamental limits of laser cooling. Published by the American Physical Society 2024

Water Evolution and Inventories of Super-Earths Orbiting Late M Dwarfs

Super-Earths orbiting M dwarf stars may be the most common habitable planets in the Universe. However, their habitability is threatened by intense irradiation from their host stars, which drives the escape of water to space and can lead to surface desiccation. We present simulation results of a box model incorporating deep-water cycling between interior and atmosphere and water loss to space for terrestrial planets of mass 1–8 M ⊕ orbiting in the habitable zone of a late M dwarf. Energy-limited loss decreases with planetary mass, while diffusion-limited loss increases with mass. Depending on where it orbits in the habitable zone, a 1 M ⊕ planet that starts with 3–8 Earth Oceans can end up with an Earthlike surface of oceans and exposed continents; for an 8 M ⊕ super-Earth, that range is 3–12 Earth Oceans. Planets initialized with more water end up as waterworlds with no exposed continents, while planets that start with less water have desiccated surfaces by 5 Gyr. Since the mantles of terrestrial planets can hold much more water than is currently present in Earth’s atmosphere, none of our simulations result in Dune planets—such planets may be less common than previously thought. Further, more water becomes sequestered within the mantle for larger planets. A super-Earth at the inner edge of the habitable zone tends to end up as either a waterworld or with a desiccated surface; only a narrow range of initial water inventory yields an Earthlike surface.

Advancing Military Medical Planning in Large Scale Combat Operations: Insights From Computer Simulation and Experimentation in NATO's Vigorous Warrior Exercise 2024.

The ongoing conflict in Ukraine from Russian invasion presents a critical challenge to medical planning in the context of multi-domain battle against a peer adversary deploying conventional weapon systems. The potential escalation of preventable morbidity and mortality, reaching a scale unprecedented since World War II, underscores the paramount importance of effective phases of care from Point of Injury (PoI)/Point of Wounding (PoW) or Point of Exposure (PoE) to Role 1 (R1) and Role 2 (R2) echelons of care.The NATO Vigorous Warrior (VW) Live Exercise (LIVEX) serves as a strategic platform for NATO and its partners, providing an opportunity to challenge operational concepts, experiment, innovate life-saving systems, and foster best practices across the Alliance. This study delineates the strategic application of the VW LIVEX platform for the adaptation of the computational simulation software Simulation for the Assessment and Optimization of Medical Disaster Management (SIMEDIS) within the context of Large-Scale Combat Operations (LSCO). The SIMEDIS computer simulator plays a pivotal role by furnishing real-time insights into the evolving injury patterns of patients, employing an all-hazards approach. This simulator facilitates the examination of temporal shifts in medical timelines and the ramifications of resource scarcity against both morbidity and mortality outcomes. The VW LIVEX provides a unique opportunity for systematic validation to evaluate the results of the computer simulator in a realistic setting and identify gaps for future concepts of operations. We report the process and methodologies to be evaluated at the VW LIVEX in far forward and retrospective medical support operations. Using the SIMEDIS simulator, we can define battlefield scenarios for varied situations including artillery, drone strikes, and Chemical, Biological, Radiological, Nuclear, and explosive (CBRNe) attacks. Casualty health progressions versus time are dependent on each threat. Mortality is computed based on the concepts found in Tactical Combat Casualty Care (TCCC) of "self-aid"/"buddy-aid" factoring in the application or absence of definitive traumatic hemorrhage control and on the distribution policy of victims to medical treatment facilities through appropriate Command and Control (C2) ("Scoop and Run" versus "Stay and Play"). The number of medical supplies available along with the number of transport resources and personnel are set and are scalable, with their effect on both morbidity and mortality quantified.Concept of Medical Operations can be optimized and interoperability enhanced when shared data are provided to C2 for prospective medical planning with retrospective data. The SIMEDIS simulator determines best practices of medical management for a myriad of injury types and tactical/operational situations relevant to policy making and battlefield medical planning for LSCO. The VW LIVEX provides a Concept Development and Experimentation platform for SIMEDIS refinement and conclusive insights into medical planning to reduce preventable morbidity and mortality. Recommending further iterations of similar methodologies at other NATO LIVEXs for validation is crucial, as is information sharing across the Alliance and partners to ensure best practice standards are met.

Novel accurate steady-state thermal resistance model for power chips embedded in TTSVs heat dissipation array

a novel oblique pyramid equivalent heat dissipation model is proposed for theoretically analyzing heat dissipation capacity of power chips with embedded TTSVs. Extra carefully researching correction of oblique thermal resistance, additional lateral thermal resistance, and thermal resistance of TSV insulation sleeve, the accurate theoretical thermal resistance model was established. Setting the FEA simulating results based on COMSOL Multiphysics as benchmark, heat dissipation effects of variation of radius of TTSV (r), thickness of the power chip (H0), and side length of the single cell (L0) have been numerically investigated. The maximum temperature relative error of the proposed model with FEA simulated results is not more than 0.2 %, 1 %, and 0.5 % for variation of r, H0, and L0, respectively. The proposed model has been theoretically and numerically proven to be effective and accurate.

On multivariate orderings of some general ordered random vectors

Ordered random vectors are frequently encountered in many problems. The generalized order statistics (GOSs) and sequential order statistics (SOSs) are two general models for ordered random vectors. However, these two models do not capture the dependency structures that may be present in the underlying random variables. In this paper, we study the developed sequential order statistics (D-SOSs) and developed generalized order statistics (D-GOSs) models that incorporate dependency structures among ordered random vectors. We then study various univariate and multivariate ordering properties of D-SOS and D-GOS models under Archimedean copula. We develop corresponding results for both one-sample and two-sample situations. We also present some simulational results and a real data analysis for illustrative purpose.

On optimal allocation of redundancies in random weighted k$$ k $$‐out‐of‐n$$ n $$ systems

AbstractRandom weighted ‐out‐of‐ systems are very useful in modeling the lifetimes of systems, wherein the success or failure of a system depends not only on its current operational status, but also on the contributions made by its components. In this paper, we consider random weighted ‐out‐of‐ systems with redundant components drawn randomly from a mixed population consisting of different subpopulations/substocks. We study different optimal allocation policies of active redundancies and minimal repair components in a random weighted ‐out‐of‐ system. Moreover, we investigate how the heterogeneity of subpopulations of items impacts the lifetime of a random weighted ‐out‐of‐ system. We also present some simulational results and a real data analysis for illustrative purpose.

A Prototype 3D Printed Suction Port Adapter for a Wireless Otoendoscope

ABSTRACTObjective: To design and fabricate a suction port adapter to use various sizes of suction cannulaswith a wireless otoendoscope enabling ear cleaning under endoscopic guidance demonstrated using an ear examination simulator. Methods:Design: Instrument InnovationSetting: Tertiary Private Training HospitalPatient: Ear Examination Simulator Results: The fabricated suction port adapters were able to hold the wireless otoendoscope and suction cannulas together, allowing simultaneous inspection of the ear canal and suctioning of ear canal debris using the Ear Examination Simulator Conclusion: Our prototype 3D-printed suction port adapters for a wireless otoendoscope mayimprove ear cleaning by enhancing the accuracy of suctioning debris and decreasing durationsince they hold the suction cannulas in place under endoscopic guidance. They may aid ENTphysicians in easier visualization and simultaneous ear cleaning of patients and improve earcleaning techniques and times, especially among less experienced physicians, but actual clinicaltrials are needed to confirm this.

The study of input power of an underwater free-damping ribbed plate in statistical energy analysis

To study the vibration characteristics of the free-damping ribbed plate with fluid load under point force excitation in statistical energy analysis (SEA), the theoretical model of input power calculation was established in this research. The simulational results from SEA commercial software validated the correctness of the proposed theoretical model. As inferred from the theoretical model, the added damping layer and ribs significantly affect the effective bending stiffness and area density, and the added fluid load only affects the effective area density. These effective parameters will affect the input power of the fluid-loaded free-damping ribbed plate, resulting in increased input power as a function frequency. The research in this paper could provide theoretical guidance on the vibroacoustic analysis of underwater complex ship structures.

Fire dynamics simulator modeling of a line-of-duty death in a firefighting training facility using recent research on materials and firefighter safety

In 2005, a line-of-duty death of an instructor at a firefighter training facility spawned research into both firefighter training and improving firefighter protective gear. Since the incident, there has been additional research into the material properties, firefighter facepiece performance, and the classification of firefighter exposures. This has been in parallel to significant improvements in the ability to model fires and predict, rather than prescribe, fire growth. As this recent body of work was not available at the time of incident investigation, the incident was revisited using the current version of Fire Dynamics Simulator. The full day of training evolutions was modeled in Fire Dynamics Simulator using recent data on wood pyrolysis (the fuel) and facepiece reaction to heat. Fire Dynamics Simulator results were evaluated against the testing done following the incident. Facepiece research was used to develop hole formation criteria that could be evaluated from Fire Dynamics Simulator predictions of facepiece exposure. This was used to compare the performance of facepieces contemporary with the incident to today’s facepieces. In addition, exposure predictions were evaluated in the context of exposure hazard categories developed for firefighter protective gear.

Study of Road Accidents by Analysis of Effects of Driving Parameters On Stopping Distance Using the Experimental Design Method and Driving Simulator

This paper aims to investigate the key factors contributing to road accidents and their interplay. A significant proportion of road accidents can be attributed to non-compliance with speed regulations, in conjunction with vehicle braking components (such as grip, road conditions, ..), as well as weather conditions. We conducted a speed measurement campaign on peri-urban roads in multiple Algerian cities to examine driving behavior and adherence to speed limits. To comprehensively understand the impact of speed, anti-lock systems, weather conditions, grip, and their interactions on a vehicle's braking distance, we employed an experimental design methodology. This approach was complemented with driving simulator tests. We expanded the experimental design to cover a range of speed variations, from 70 to 130 km/h, enabling us to explore the influence of various driving parameters on braking distance. Through statistical analysis of influence coefficients from 16 driving simulator tests, we established a model that represents the relationship between "objective functions" and "influence factors." This mathematical model was validated using simulator results. Our study revealed that braking distance is primarily affected by speed and weather conditions. Notably, the analysis of the road speed measurement campaign demonstrated that 55% of road users fail to adhere to speed limits.

Comparison of power system flow analysis methods of IEEE 5-bus system

Load flow analysis is a crucial tool used by electrical engineers for simulating the power system. It is aimed at examining the most possible way of operating and controlling a power system and the exchange of power flow within the power system. For the economic and optimal operation of power systems, the most essential task is to find the most feasible solution technique suitable and efficient for the study of power generation, transmission, and distribution. There are various power flow study solution techniques, and for some solution techniques, the simulation of the system can take a long time, which prevents the simulator from attaining a higher accuracy result for the power flow simulation due to the interrupting rise and fall in power demand from the consumer, which also affects the power generation as well. This paper discusses the comparison of various techniques used in load flow studies with the assistance of a small power system with five buses. The numerical solution techniques used are the fast decoupled load flow solution technique, the Gauss-Seidel solution technique, and the Newton-Raphson solution technique for a power flow study solution on an IEEE 5-bus using MATLAB/Simulink.

WR21 marine gas turbine thermodynamic simulator for ship propulsion studies

An original modular mathematical model, based on physical laws, for steady state and dynamics performance simulation of the WR21 gas turbine is presented in the paper. The model, developed in Matlab-Simulink language, is organized in modular form. Each gas turbine component (i.e. compressor, turbine, combustor, heat exchanger) is modelled in a specific simulator block, that simulates the performance of its pertinent component by means of steady state performance maps and/or correlations, time dependent momentum, energy and mass equations, nonlinear algebraic equations. The great application flexibility of the component simulator modules, allows to modelling any gas turbine layout (i.e. axial or radial flow compressor and turbine, rotating shafts number, heat exchangers). The WR21gas turbine, developed mainly for marine propulsion application, is a three shafts gas turbine with thermal regeneration. It is characterized by a high thermodynamic efficiency, which remains high up to 30% of the design power. The WR21 simulator results are validated by comparison with manufacturer or literature data. The WR21 gas turbine main performances are compared to those of the LM 2500 gas turbine, obtained by a previously author paper. The LM 2500 is the gas turbine currently most used in naval propulsion plants. In the article, a comparison between the steady state working data of the two gas turbines is reported in tabular and graphical form and commented.

How Drivers Lose Control of the Car

<div>After a severe lane change, a wind gust, or another disturbance, the driver might be unable to recover the intended motion. Even though this fact is known by any driver, the scientific investigation and testing on this phenomenon is just at its very beginning, as a literature review, focusing on SAE Mobilus<sup>®</sup> database, reveals. We have used different mathematical models of car and driver for the basic description of car motion after a disturbance. Theoretical topics such as nonlinear dynamics, bifurcations, and global stability analysis had to be tackled. Since accurate mathematical models of drivers are still unavailable, a couple of driving simulators have been used to assess human driving action. Classic unstable motions such as Hopf bifurcations were found. Such bifurcations seem almost disregarded by automotive engineers, but they are very well-known by mathematicians. Other classic unstable motions that have been found are “unstable limit cycles.” The driving simulator results have been reproduced by experimental tests on track. We have assessed that the driver’s steering action can make the car motion unstable if a proper disturbance has acted. The delay of the driver’s steering action is the primary cause for the generation of limit cycles. Future automated vehicles should be conceived by focusing on the addressed phenomenon.</div>

Identifying the effects of driving parameters on stopping distance to reduce accident risks

The object of the research is the most important factors causing road accidents. This paper aimed to study the effects of this factors and their interactions on the stopping distance function. Understanding this function through simulation and comparing the results with mathematical models and experimental tests will help to reduce the number of road accidents. A large part of road accidents is linked to non-compliance with regulatory speed associated with vehicle braking system (grip, road and tires) and weather conditions. A speed measurement campaign on peri-urban roads was carried out to study driving behavior and compliance with speed limits in several Algerian cities. An experimental modelling of speed, anti-lock system, weather, grip and their interaction effects on the stopping distance of a vehicle using the experimental design method, combined with driving simulator tests was been conducted. The developments of experimental design with speed variation ranges (70 and 130 km/h) were necessary to study the influence of the various driving parameters on stopping distance. The mathematical model developed has been validated by the results obtained on the simulator. The experimental design method and simulator results were used to identify and define the important parameters that influence the braking distance. The results show that the stopping distance (SD) is mainly influenced by the vehicle speed (S), the weather conditions (M), and their interaction. The increase due to speed leads to an increase in the stopping distance with an estimated effect of 54.30 m. When the speed varies between its lower experimental level (70 km/h) and its higher level (130 km/h), it is estimated that the stopping distance will increase by 54.30 m. The analysis of the road speed measurement campaign, 55 % of road users do not obey the speed limits. The results obtained in this study can be applied to other countries, only the parameters need to be adjusted.

A Novel Optimization Method for TEG System Performance Based on Temperature and Heat Flux

The thermoelectric generator (TEG) can convert heat to electricity and is widely used. To overcome the limitation for low efficiency of thermoelectric materials, optimizing the performance of TEG in given system is necessary. This study proposes a method to match individual TEG components to the system environment based on two boundary conditions—temperature and heat flux. With this method, TEG geometrical parameters can be determined to optimize the system performance by varying temperature as an independent variable. Using this method, the TEG in an undersea Radioisotope thermoelectric generator (u‐RTG) is optimized. The TEG system exhibits an output power of 14.10 W when powered by a 200 W heat source. The simulate result in the comprehensive system model of u‐RTG is 14.04 W, which has 0.45% deviation from the TEG optimization result. It is proved that the TEG optimized by this method matches the system, the optimization results are accurate.