Hybrid Simulation Model Research Articles

Hybrid modeling and simulation for innovation deployment strategies

PurposeThe purpose of this paper is to provide a simulation model for assessing innovation deployment strategies by evaluating and comparing their outcomes using a hybrid modeling and simulation of agent‐based modelling and simulation (ABMS) and system dynamics (SD). Since successful deployment of innovations in any organization is as important as the innovations themselves, how to choose a suitable deployment strategy and assess its effectiveness before actual implementation is a critical task.Design/methodology/approachThis paper adopts a hybrid modeling and simulation approach combining the advantages of agent‐based modeling and system dynamics to study the activities and strategies involved in innovation deployment. The developed model was verified and validated with the data from GM's OnStar project.FindingsThe research demonstrates that evaluating various deployment strategies for desirable results through hybrid modeling and simulation is possible and useful by finding critical factors and making appropriate forecast, which would aid managers in assessment of innovation deployment strategies and deployment decision‐making processes.Research limitations/implicationsThe hybrid modeling and simulation approach provides a powerful tool in various study fields, not only in industries, but also suitable to evaluate the system outputs in both macroscopic and microscopic point of view for many strategy‐making or consulting firms. The presented work is meant for proof‐of‐concept, so numerous expansions are necessary for use in different projects.Practical implicationsFor the case evaluated in this paper, it is found that a customer‐oriented strategy outperforms a cost‐oriented strategy in market share as well as customer satisfaction and profit. Cooperation and R&D are essential innovation drivers, but from the study, customer satisfaction does not solely depend on technical advantages. Alliance is a key factor to reduce the cost and risk of uncertainties. The structure and approach of the presented hybrid simulation model can be adopted for other cases to derive conclusions.Originality/valueThe originality of the paper lies in the way of adopting a hybrid modeling and simulation approach to study the effects of innovation deployment strategies. The model can be modified and used in a wide range of organizations to evaluate different strategies and aid decision‐making processes.

Hybrid Simulation for Knee Arthrocentesis: Improving Fidelity in Procedures Training

Procedures form a core competency for internists, yet many do not master these skills during residency. Simulation can help fill this gap, but many curricula focus on technical skills, and overlook communication skills necessary to perform procedures proficiently. Hybrid simulation (HS) is a novel way to teach and assess procedural skills in an integrated, contextually-based way. To create a HS model for teaching arthrocentesis to internal medicine residents. Internal medicine residency program at the University of Toronto. Twenty four second-year internal medicine residents. Residents were introduced to HS, given practice time with feedback from standardized patients (SPs) and faculty, and assessed individually using a different scenario and SP. Physicians scored overall performance using a 6-point procedural skills measure, and both physicians and SPs scored communication using a 5-point communication skills measure. Realism was highly rated by residents (4.13/5.00), SPs (4.00) and physicians (4.33), and was perceived to enhance learning. Residents' procedural skills were rated as 4.21/6.00 (3.00 - 5.00; ICC = 0.77, [0.53 - 0.92]), comparable to an experienced post-graduate year (PGY) 2-3; and all but one resident was considered competent. HS facilitates simultaneous acquisition of technical and communication skills. Future research should examine whether HS improves transfer of skills to the clinical setting.

Perspective: hybrid systems combining electrostatic and electrochemical nanostructures for ultrahigh power energy storage

Time-varying energy profiles of renewable sources, electric vehicles, end user demands, portable devices, novel military applications and more, require high power as well as high energy density in storage systems. Electrochemical capacitors (EECs), with higher power than batteries, benefit from nanostructured geometries that further increase their power capability. Nanostructured electrostatic capacitors (ESCs) are known to have much higher power capability than EECs, though lower energy density. The physical and chemical mechanisms by which EECs and ESCs function in charge/discharge are completely different, as are their electrical specifications and constraints. We consider for the first time how the contrasting characters of electrochemical and electrostatic nanostructured capacitors might be combined in a heterogeneous hybrid circuit to achieve better power and energy performance than either device alone. While the benefits of hybrid circuits have been previously considered for electrochemical devices – i.e., battery and electrochemical capacitor – this perspective article demonstrates for the first time that hybrid storage circuits of heterogeneous devices can exploit the very high power of electrostatic devices, in concert with electrochemical devices. Using response surface models from our own experimental results with nanostructured ESC and ECC devices, we develop a hybrid simulation model combining the two types of devices, recognizing the intrinsic nonlinearities and constraints of each. We demonstrate that charge capture by the ESC and subsequent rapid transfer to the ECC compensates for the lower power capability of the ECC while avoiding energy loss by ESC leakage currents. Although more sophisticated models and simulations are warranted in the future, these initial results underscore the opportunity that ESC devices and hybrid circuits offer for storage applications which require ultrahigh power performance.

Solar wind charge exchange X-ray emission from Mars

Aims. We study the soft X-ray emission induced by charge exchange (CX) collisions between solar-wind, highly charged ions and neutral atoms of the Martian exosphere. Methods. A 3D multi species hybrid simulation model with improved spatial resolution (130 km) is used to describe the interaction between the solar wind and the Martian neutrals. We calculated velocity and density distributions of the solar wind plasma in the Martian environment with realistic planetary ions description, using spherically symmetric exospheric H and O profiles. Following that, a 3D test-particle model was developed to compute the X-ray emission produced by CX collisions between neutrals and solar wind minor ions. The model results are compared to XMM-Newton observations of Mars. Results. We calculate projected X-ray emission maps for the XMM-Newton observing conditions and demonstrate how the X-ray emission reflects the Martian electromagnetic structure in accordance with the observed X-ray images. Our maps confirm that X-ray images are a powerful tool for the study of solar wind - planetary interfaces. However, the simulation results reveal several quantitative discrepancies compared to the observations. Typical solar wind and neutral coronae conditions corresponding to the 2003 observation period of Mars cannot reproduce the high luminosity or the corresponding very extended halo observed with XMM-Newton. Potential explanations of these discrepancies are discussed.

Characteristics of plume plasma and its effects on ablation depth during ultrashort laser ablation of copper in air

The characteristics of plume plasma induced by ultrashort laser ablation of copper in air are studied experimentally and theoretically in this paper. The plasma front evolutions are captured using a high-speed intensified charge-coupled device camera, while the plasma temperature and electron number density evolutions are obtained from the plasma emission spectra measured by a high-precision spectrometer. For the theoretical study, a hybrid simulation model is proposed to combine an atomistic model for the early stage and a hydrodynamic model for the later stage. The simulation model is validated against the measurement results and shown to be capable of predicting plasma properties for a broader range of fluence, without being constrained by the signal strength as in the measurements. Both experimental and theoretical results show that the nonlinear relationship between plasma properties and laser fluence directly relates to the relationship between ablation depth and laser fluence. Therefore, the measurable and predictable plasma properties reveal the underlying ablation mechanism that has been studied primarily by theory.

Design classes for hybrid simulations involving agent-based and system dynamics models

Hybrid simulation involves the use of multiple simulation paradigms, and is becoming an increasingly common approach to modelling modern, complex systems. Despite growing interest in its use, little guidance exists for modellers regarding the nature and variety of hybrid simulation models. Here, we concentrate on one particular hybrid – that involving agent-based and system dynamics models. Based on an up-to-date review of the literature, we propose three basic types of hybrid agent-based system dynamics simulations, referred to here as interfaced, integrated and sequential hybrid designs. We speculate that the classification presented may also be useful for other classes of hybrid simulations.

Global‐scale hybrid simulation of cusp precipitating ions associated with magnetopause reconnection under southward IMF

With a 3‐D global‐scale hybrid simulation model, we investigate the energy spectra of cusp precipitating ions and issues associated with magnetopause reconnection under a southward IMF. Both the spatial and temporal energy spectra of cusp precipitating ions are computed by tracing trajectories of the transmitted magnetosheath ions. The spatial spectrum shows a dispersive feature consistent with satellite observations, with higher energy particles at lower latitudes and lower energy particles at higher latitudes. The simulation reveals (1) how and where particles are transmitted from the solar wind into the magnetosphere via direct magnetic reconnection on the dayside; (2) how the features of the spectra are related to ongoing magnetic FTEs; and (3) how the motion of the cusp, particularly the latitudinal variation of the open/closed field line boundary, is correlated with the dayside reconnection and reflected in the energy flux spectra of the precipitating ions as a function of time.

방사소음 및 투과소음에 대한 승용차량 대시패널의 설계인자 별 영향도 분석

While a dash panel component, close to passengers, plays a very important role to protect heat and noise from a power train, it is also a main path that transfers vibration energy and eventually radiates acoustic noise into the cavity. Therefore, it is important to provide optimal design schemes incorporating sound packages such as a dash isolation pad and a floor carpet, as well as structures. The present study is the extension of the previous investigation how design variables affect sound radiation, which was carried out using the simple plate and framed system. A novel FE-SEA hybrid simulation model is used for this study. The system taken into account is a dash panel component of a sedan vehicle, which includes front pillars, front side members, a dash panel and corresponding sound packages. Design variables such as panel thicknesses and sound packages are investigated how they are related to two main NVH indexes, sound radiation power(i.e. structure-borne) and sound transmission loss(i.e. air borne). In the viewpoint of obtaining better NVH performance, it is shown that these two indexes do not always result in same tendencies of improvement, which suggests that they should be dealt with independently and are also dependent on frequency regions.

Dynamics of autonomously acting products and work systems in production and assembly

Autonomous production is characterized by local and autonomous decision making of intelligent logistic objects such as work systems that adjust production rates and parts that decide which products they “want” to become and which orders they will fill. It is important to understand and have confidence in dynamic interactions of these objects and their resulting performance. In this paper the dynamic interaction of autonomous products and work systems is investigated using a hybrid simulation model and a control-theoretic model. Results obtained using both models show that these dynamic interactions can be well behaved and predictable. Through linearized models of continuous input flows at nominal rates, tools of control theory are shown to build confidence in complex system dynamic behavior of interacting autonomous logistics objects when decision-making logic is modeled in a way that makes control-theoretic analyses tractable.

Combining system dynamics and discrete event simulations: Overview of hybrid simulation models

Simulation and modelling has been widely accepted as one of the most important aspects of the Industrial engineering. The application and use of simulation models has grown exponentially since the 1950’ until today. Over the years, the complexity of the simulated aspects has been adapted to the complexity of the analysed cases which has risen proportionally too. That is why techniques used many years ago, can often not give an adequate representation of the real world any more. For that reason, we propose to use hybrid simulation models, which are a combination of simulation paradigms in order to cope with this problem. In this paper, we will give an overview of selected researches and applications with an emphasis on Discrete Event Simulation and System Dynamics, as one of the core simulation based techniques in that area. Key words: Hybrid, Simulation, Model, System Dynamics, Discrete-event simulation

Dynamic Martian magnetosphere: Transient twist induced by a rotation of the IMF

Simulation studies of the Martian environment are usually restricted to stationary situations under various steady conditions of the solar wind and solar radiation. Dynamic transients and their implications have so far attracted little attention although global simulation models can provide valuable insights to understand disagreements between simulations and in situ observations. We make use of a three dimensional multispecies hybrid simulation model to investigate the response of the Martian plasma environment to a sudden rotation of the IMF. The simulation model couples charged and neutral species via three ionisation mechanisms: the absorption of solar extreme ultraviolet radiation, the impact of solar wind electrons, and the charge exchange between ions and neutral atoms. When a rotational discontinuity conveyed by the solar wind reaches the Martian environment the bow shock adapts quickly to the new solar wind conditions in contrast to the induced magnetosphere, especially the magnetic lobes in the wake. Timescales necessary to recover a stationary state can be estimated from such simulations and have some implications for space observations especially in the use of magnetic field proxies and for organizing particle measurements made by a spacecraft like Mars Express without an onboard magnetometer.

A Hybrid Simulation Model to Test Behaviour Designs in an Emergency Evacuation

The paper shows a computer simulation in order to specify and implement a simulation model that allows to investigate behavioural dynamics for pedestrians in an emergency evacuation. We present a hybrid model where the dynamics of fire and smoke propagation are modelled by means of Cellular Automata and for simulating people behaviour we are using goal oriented Intelligent Agents. The model consists of two sub-models, called environmental and pedestrian. We have prototyped a methodology that is able to model some of the frequently observed human behaviours in evacuation exercises. The decision making-process is determined by the current behaviour. The set of behaviours are included in an engine of behaviour associated to each agent. This hybrid model along with the computational methodology allows us building an artificial environment populated with autonomous agents, which are capable of interacting with each other. Furthermore, in order to test some human behaviours, we developed simple exercises where the model is applied to the simulation of evacuation processes.

Contribution of Interfacility Patient Movement to Overall Methicillin-Resistant Staphylococcus aureus Prevalence Levels

The effect of patient movement between hospitals and long-term care facilities (LTCFs) on methicillin-resistant Staphylococcus aureus (MRSA) prevalence levels is unknown. We investigated these effects to identify scenarios that may lead to increased prevalence in either facility type. We used a hybrid simulation model to simulate MRSA transmission among hospitals and LTCFs. Transmission within each facility was determined by mathematical model equations. The model predicted the long-term prevalence of each facility and was used to assess the effects of facility size, patient turnover, and decolonization. Analyses of various healthcare networks suggest that the effect of patients moving from a LTCF to a hospital is negligible unless the patients are consistently admitted to the same unit. In such cases, MRSA prevalence can increase significantly regardless of the endemic level. Hospitals can cause sustained increases in prevalence when transferring patients to LTCFs, where the population size is smaller and patient turnover is less frequent. For 1 particular scenario, the steady-state prevalence of a LTCF increased from 6.9% to 9.4% to 13.8% when the transmission rate of the hospital increased from a low to a high transmission rate. These results suggest that the relative facility size and the patient discharge rate are 2 key factors that can lead to sustained increases in MRSA prevalence. Consequently, small facilities or those with low turnover rates are especially susceptible to sustaining increased prevalence levels, and they become more so when receiving patients from larger, high-prevalence facilities. Decolonization is an infection-control strategy that can mitigate these effects.

A hybrid simulation framework for the evaluation of common radio resource management scenarios

We present a hybrid modeling framework with interacting simulative and analytic submodels for the efficient evaluation of common radio resource management (CRRM). It enables a cost–benefit investigation of different CRRM algorithms and architectures. Centralized as well as decentralized scenarios can be clearly defined by five standard components, namely the radio access system, the environment, the user equipment, the CRRM information manager, and the CRRM decider. The costs and time consumption of CRRM operations are taken into account via chargeable messages. The clarity of the model enables an efficient investigation of CRRM algorithms based on optimization theory, game theory, physical models, and other methods. The resulting framework has been implemented as a hybrid simulation model using the discrete event simulation system OMNeT++. A convenient and straightforward integration of different wireless network technologies and user service demands is also supported; models for the universal mobile telecommunications system (UMTS) and the global system for mobile communications/enhanced general packet radio service (GSM/EGPRS) are already integrated. The scope of the proposed framework is demonstrated by the evaluation of realistic scenarios.

Global-scale hybrid simulation of dayside magnetic reconnection under southward IMF: Structure and evolution of reconnection

[1] Magnetopause reconnection is investigated with our 3-D self-consistent global hybrid simulation model. The magnetic configuration and evolution of Flux Transfer Events (FTEs) and the associated ion density and ion velocity distribution at various locations on the magnetopause are investigated. The results reveal the following. (1) Multiple X lines are formed during the magnetopause reconnection, which lead to both FTEs and quasi-steady-type reconnection under a steady solar wind condition. The resulting bipolar signature of local normal magnetic field of FTEs is consistent with satellite observations. (2) A greater-than-20% plasma temperature rise is seen at the center of a FTE, compared to that of the upstream plasma in the magnetosheath. The temperature enhancement is mainly in the direction parallel to the magnetic field because of the mixing of ion beams. (3) Flux ropes that lead to FTEs form between X lines of finite lengths and evolve relatively independently. The ion density is enhanced within FTE flux ropes because of the trapped particles, leading to a filamentary global density. (4) Different from the previous understanding based on the asymmetric density across the magnetopause, a quadrupole magnetic field signature associated with the Hall effects is found to be present around FTEs. (5) A combination of patchy reconnection and multiple X line reconnection leads to the formation of reconnected field lines from the magnetosphere to IMF, as well as the closed field lines from the magnetosphere to the magnetosphere in the magnetopause boundary layer.

A hybrid systems model to simulate cyber interdependencies between critical infrastructures

Critical infrastructures (CI) depend on communications and information technology infrastructure (CITI) for many of their key functionalities, which is known as cyber interdependency. In this paper, we presented a cyber interdependency simulation technique that is based on the idea that overall performance of a CI network is determined by the behaviour of its components at multiple time scales. Accordingly, for cyber interdependency simulation, we decomposed CI network into two time scales; regular CI events are captured in large time-steps and data communication network events are captured in smaller time-steps. Two different simulators are used for each of these partitions and results from both simulations are synchronised appropriately. A real life example is presented to demonstrate the accuracy and usefulness of our approach. The hybrid simulation model gives significant flexibility to plug-in domain specific models into the critical infrastructure simulator for accurate and efficient solution.

Research on Skid Control of Small Electric Vehicle (Effect of Regenerative Braking System in Skidding Condition)

In recent years, electric vehicles have come to be widely used. Most of small electric vehicles only provide seat belts as safety equipment. , the vehicle using In-wheel motor system as driving unit in particular have no space for an antilock braking system, which is a basic skid control system. For the same reason, small electric vehicles using In-wheel motor system employ a mechanical braking system rather than a hydraulic braking system. Although the mechanical system is compact, the stiffness of the system is smaller than that of the hydraulic braking system, and the responsiveness of the braking force of the mechanical system is low. Therefore, small electric vehicles may be considered that they lack driving safety. The purpose of the present study is to improve the safety of small electric vehicles. In this report, the effects of regenerative brake and Anti-lock brake system for braking performance were examined. A hybrid simulation model comprising velocity and the pressure of the brake fluid in the brake piping by the characteristic curve method was constructed for the hydraulic and mechanical systems. The braking pressure of the braking unit, which includes the antilock braking unit modeled by the lumped constant model, was controlled to compensate for the small stiffness value of the mechanical braking system.

G100023 Research on Skid Control of Small Electric Vehicle with Hydraulic-Mechanical Hybrid Brake System : Effect of Regenerative Brake on Turning Motion

The studies of safety and stability systems of small electric vehicles can be divided broadly into two areas of interest, namely skid control by motor sensors and safety improvement by Anti-Lock Braking System (ABS). However, for a small electric vehicle, there is no space to install a brake unit for ABS in driving tire because an in-wheel motor system is used as the driving unit, and there have been no simulations of an ABS that combines a mechanical brake system and a hydraulic brake system. The purpose of the present study is to improve the safety and stability systems of the small electric vehicle. The effect of a regenerative brake on a turning motion and the influences of the weight movement with the suspension were investigated. In this report, the hydraulic-mechanical hybrid brake system was combined with the ABS as a braking system for a small electric vehicle. A hybrid simulation model comprising velocity and the pressure of the brake fluid in the brake piping by the characteristic curve method was constructed for the hydraulic and mechanical brake system. The braking pressure of the braking unit, which included the antilock braking unit modeled by the lumped constant model, was controlled to compensate for the small stiffness value of the mechanical braking system.

Modeling of Fluid Dynamics and Thermo-Chemical System in Halogen Lamp Operation

One of the key elements in improving lamp efficiency is understanding and controlling the halogen transport process. Therefore, it is worthwhile to build a model that depicts this process and can be applied to the study of various types of lamps. We examined the halogen transport process in a lamp by using a hybrid simulation model based on fluid dynamics and chemical equilibrium.

Modeling Low Climate Stabilization with E3MG:1 Towards a ‘New Economics’ Approach to Simulating Energy-Environment-Economy System Dynamics

The literature on climate stabilization modeling largely refers to either energy-system or inter-temporal computable general equilibrium/optimal growth models. We contribute with a different perspective by deploying a large-scale macro-econometric hybrid simulation model of the global energy-environment-economy (E3MG) adopting a “New Economics” approach. We use E3MG to assess the implications of a low-stabilization target of 400ppm CO2 equivalent by 2100, assuming both fiscal instruments and regulation. We assert that if governments adopt more stringent climate targets for rapid and early decarbonization, such actions are likely to induce more investment and increased technological change in favor of low-carbon alternatives. Contrary to the conventional view on the economics of climate change, a transition towards a low-carbon society as modeled with E3MG leads to macroeconomic benefits, especially in conditions of unemployment, with GDP slightly above a reference scenario, depending on use of tax or auction revenues. In addition, more stringent action can lead to higher benefits.