High Physical Fidelity Research Articles

Super-resolution reconstruction of turbulence for Newtonian and viscoelastic fluids with a physical constraint

Super-resolution reconstruction (SR) of turbulent flow fields with high physical fidelity from low-resolution turbulence data is a novel and cost-effective way in a turbulence study. However, some naive image-to-image machine learning methods often produce nonphysical features inconsistent with the physical characteristics of turbulence. The present work proposes, respectively, convolutional neural network and generative adversarial network-based turbulence SR models using the kinetic energy spectra of turbulence flow as a physical constraint. The models have been validated in turbulence SR reconstruction for a Newtonian fluid under the flow condition of homogeneous isotropic turbulence at Reynolds number, Re=3140 and 4710 and viscoelastic fluid at the same Re numbers and Weisenberg number, Wi=0.796 and 1.194 (the elasticity number El=Wi/Re=0.000 254), respectively. The results show that with the energy spectra constraint (ESC), not only the nonphysical features occurred in the energy spectra of velocity field could be eliminated by the SR models, the errors of their reconstructed vorticity fields in comparison with the results of direct numerical simulation are also significantly smaller than those of the SR models without ESC. Therefore, incorporation of physical constraints is vital in preserving physical characteristics in SR of turbulent flow.

Optimized compact finite volume formulation with dispersion relation preserving characteristics in structured space discretizations

Computationally extensive fluid flow simulations usually require numerical schemes with a high degree of numerical precision, where high wavenumber and frequency capturing capability is desired in solutions with high physical fidelity. Numerical dispersion and diffusion errors must be reduced to a minimum in order to caputre low amplitude and high frequency flow aspects, such as flow induced sound waves and minor instabilities. Such schemes also must be capable of dealing with flow discontinuities, such as shockwaves and expansion waves in cases where the flow velocity stands near or above sound velocity. In this work the Dispersion Relation Preserving (DRP) optimization is formally extended to the compact Finite Volume (FV) framework where the error is minimized along a given spectral interval. This is done by equaling the resulting algebraic compact spectral optimized Finite Difference (FD) operators with the Finite Volume formulation with the desired numeric characteristics. Numerical tests are carried over linear and nonlinear governing equations models for one and three-dimensional cases, where the travelling Gaussian wave, the transient expansion wave and the smooth to nonsmooth step wave flows are considered. The proposed compact DRP FV schemes surpasses its counterparts in some numerical tests while maintaining comparable capabilities with other more basic schemes in the remaining numerical tests. Excellent broadband content capturing capability is observed, while possessing reduced numerical instabilities generation.

Cosmic Reionization on Computers: Statistics, Physical Properties, and Environments of Lyman Limit Systems at z ∼ 6

Lyman limit systems (LLSs) are dense hydrogen clouds with high enough H i column densities to absorb Lyman continuum photons emitted from distant quasars. Their high column densities imply an origin in dense environments; however, the statistics and distribution of LLSs at high redshifts still remain uncertain. In this paper, we use self-consistent radiative transfer cosmological simulations from the Cosmic Reionization on Computers (CROC) project to study the physical properties of LLSs at the tail end of cosmic reionization at z ∼ 6. We generate 3000 synthetic quasar sight lines to obtain a large number of LLS samples in the simulations. In addition, with the high physical fidelity and resolution of CROC, we are able to quantify the association between these LLS samples and nearby galaxies. Our results show that the fraction of LLSs spatially associated with nearby galaxies increases with H i column density. Moreover, we find that LLSs that are not near any galaxy typically reside in filamentary structures connecting neighboring galaxies in the intergalactic medium (IGM). This quantification of the distribution and association of LLSs to large-scale structure informs our understanding of the IGM–galaxy connection during the “Epoch of Reionization,” and provides a theoretical basis for interpreting future observations.

The Challenge of Mass Casualty Incident Response Simulation Exercise Design and Creation: A Modified Delphi Study

Introduction:A Mass Casualty Incident response (MCI) full scale exercise (FSEx) assures MCI first responder competencies. Simulation and serious gaming platforms (Simulation) have been considered to achieve and maintain first responder competencies with the challenge of the FSEx. The translational science (TS) T0 question: How can students achieve similar MCI competencies through the use of simulation MCI exercises as with a FSEx?Method:Initial TS phase T1: Scoping ReviewA Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Review was conducted to develop statements for the TS second phase T2 modified Delphi study. 1320 reference titles and abstracts were reviewed with 215 full articles progressing for full review leading to 97 undergoing data extraction.Second TS stage T2: modified Delphi studyThe database was analyzed and initial draft statements were created. Selected modified Delphi experts were presented with 27 statements with instructions to rank each statement on a seven-point linear numeric scale, where 1 = disagree and 7 = agree. Consensus amongst experts was defined as a standard deviation ≤1.0.Results:After three modified Delphi rounds 19 statements attained consensus and eight did not attain a consensus.Conclusion:The modified Delphi experts agreed that the simultaneous integration of individual duty and incident management skills should be incorporated into simulation MCI exercise design to achieve competencies depending on high physical fidelity to develop the individual’s manual abilities, as well as high conceptual fidelity, to develop the individual’s clinical reasoning and problem-solving skills. MCI simulation exercises can be developed to achieve similar competencies as FSExs incorporating the 19 statements that attained consensus through the TS phases of a scoping review (T1) and modified Delphi study (T2). The TS process should continue with development of these exercises in the T3 implementation stage and then evaluated in the T4 stage.

Physics-separating artificial neural networks for predicting initial stages of Al sputtering and thin film deposition in Ar plasma discharges

Simulations of Al thin film sputter depositions rely on accurate plasma and surface interaction models. Establishing the latter commonly requires a higher level of abstraction and means to dismiss the fundamental atomic fidelity. Previous works on sputtering processes addressed this issue by establishing machine learning surrogate models, which include a basic surface state (i.e. stoichiometry) as static input. In this work, an evolving surface state and defect structure are introduced to jointly describe sputtering and growth with physics-separating artificial neural networks. The data describing the plasma–surface interactions (PSIs) stem from hybrid reactive molecular dynamics/time-stamped force bias Monte Carlo simulations of Al neutrals and Ar+ ions impinging onto Al(001) surfaces. It is demonstrated that the fundamental processes are comprehensively described by taking the surface state as well as defect structure into account. Hence, a machine learning PSI surrogate model is established that resolves the inherent kinetics with high physical fidelity. The resulting model is not restricted to input from modeling and simulation, but may similarly be applied to experimental input data.

Real Or Not Real: The Impact of the Physical Fidelity of Virtual Learning Resources on Learning Anatomy.

Technological advancements have made it possible to create realistic virtual representations of the real world, although it is unclear in medical education whether high physical fidelity is required in virtual learning resources (VLRs). This study, therefore, aimed to compare the effectiveness of high-fidelity (HF) and low-fidelity (LF) VLRs for learning anatomy. For this study, HF and LF VLRs were developed for liver anatomy and participants were voluntarily recruited from two cohorts (cohorts 1 and 2). Knowledge outcomes were measured through pre- and post-tests, task outcomes including activity score and completion time were recorded and participants' perceptions of the VLRs were surveyed. A total of 333 participants (165 HF and 168 LF) took part in this study. Knowledge outcomes were higher for the HF activity in cohort 1 and for the LF activity in cohort 2, although not significantly. There were no significant differences in activity score within either cohort, although completion time was significantly longer for the HF activity in cohort 1 (P=0.001). There were no significant differences within either cohort in perceptions of the VLRs regarding usefulness for reviewing conceptual knowledge, esthetics, quality, mental effort experienced, or future use, although the LF VLR was scored significantly higher regarding the value for understanding in cohort 1 (P=0.027).This study suggests that high physical fidelity is not necessarily required for anatomy VLRs, although may potentially be valuable for improving knowledge outcomes. Also, level of prior knowledge may be an important factor when considering the physical fidelity of anatomy VLRs.

A review on snake robot testbeds in granular and restricted maneuverability spaces

This article reviews the state of the art in evaluating snake robots for small spaces such as a collapsed building where the snake is either locomoting in restricted maneuverability spaces, such as narrow pipes or tunnels, or pushing through granular regions, such as dirt and rubble. It makes recommendations on designing a testbed that can enable a comprehensive evaluation of a snake robot’s overall capability and an objective comparison of different snakes. A survey of 31 papers reveals that 20 testbeds were used to test snake robots in restricted maneuverability environments. All of those were built specifically to test a particular snake robot rather than for comparison with other snake robots, but each offers insights into designing comprehensive, comparative testbeds. The article analyzed these 20 testbeds in terms of how well they addressed the previously established disaster robotics metrics of scale (a dimensionless number) and four traversability elements, i.e. verticality, tortuosity, accessibility elements, and surface properties. This review suggests that two kinds of general testbeds are in need for the snake robot community: (1) a testbed with high physical fidelity for measuring suitability for a target application, and (2) a testbed which provides a dimensionless comparison of different snake robots. The review is expected to benefit the community in several ways. It can help form a consensus on a suite of metrics and test methods to incorporate into a testbed for evaluating and comparing different types of snake robots and capturing the performance of snake robots in more realistic work envelopes. The metrics and test methods can also pro-actively inform snake robot design as they offer more formally quantified work envelopes, thus accelerating technology transfer. The use of scale and traversability is expected to be applicable to robots in general.

Factor effecting the capability to jettison an S92 push-out window

The need for human factors research within global offshore helicopter operations cannot be understated. Presently, there is extremely limited information about the force required to jettison a helicopter exit. This information should be readily available in the helicopter design information. This study explored factors that influence the ability of a passenger to successfully jettison a Sikorsky S92 helicopter push-out window under simulated conditions. The results clearly indicated that the technique used to jettison the window plays a significant role in success rates. It was also noted that the location at which the strike was applied significantly changed the force that could be applied. Given these results, it is possible that prior to each flight offshore, passengers could physically demonstrate their capacity to open a high physical fidelity (i.e., requires the same applied loads to jettison as those in the actual helicopter) simulated exit.

The Effect of Model Fidelity on Learning Outcomes of a Simulation-Based Education Program for Central Venous Catheter Insertion.

Simulation-based education for central venous catheter (CVC) insertion has been repeatedly documented to improve performance, but the impact of simulation model fidelity has not been described. The aim of this study was to examine the impact of the physical fidelity of the simulation model on learning outcomes for a simulation-based education program for CVC insertion. Forty consecutive residents rotating through the medical intensive care unit of an academic medical center completed a simulation-based education program for CVC insertion. The curriculum was designed in accordance with the principles of deliberate practice and mastery learning. Each resident underwent baseline skills testing and was then randomized to training on a commercially available CVC model with high physical fidelity (High-Fi group) or a simply constructed model with low physical fidelity (Low-Fi group) in a noninferiority trial. Upon completion of their medical intensive care unit rotation 4 weeks later, residents returned for repeat skills testing on the high-fidelity model using a 26-item checklist. The mean (SD) posttraining score on the 26-item checklist for the Low-Fi group was 23.8 (2.2) (91.5%) and was not inferior to the mean (SD) score for the High-Fi group of 22.5 (2.6) (86.5%) (P < 0.0001). Residents in both groups judged the training program to be highly useful despite perceiving a lesser degree of physical realism in the low-fidelity model compared with the high-fidelity model (P = 0.05). Simulation-based education using equipment with low physical fidelity can achieve learning outcomes comparable with those with high-fidelity equipment, as long as other aspects of fidelity are maintained and robust educational principles are applied during the design of the curriculum.

Forces required to jettison a simulated S92 passenger exit: Optimal helicopter underwater egress training techniques

This paper outlines the first known examination of the forces required to jettison a simulated exit used during helicopter underwater egress training (HUET). To capture the forces placed on the simulated cabin exit, a purpose build force plate was designed to replace an existing simulator exit used during HUET. A 25-point map was created to identify specific jettison forces required across the entire exit surface. Ten participants completed a total of 120 underwater egress sequences in–air and in-water from a normal flight and fully compressed crash attenuating seat position. The results indicate that the force required to jettison the simulated exit is significantly different in relationship to location on the exit surface. From the results, it can be concluded that helicopter underwater egress training protocols should ensure that offshore candidates are informed of the different force requirements as well as have the opportunity to practice jettisoning a high physical fidelity exit from a fully compressed crash attenuating seat.Relevance to industry: This is the first paper to investigate the forces required to jettison a simulated S92 exit used in an underwater egress simulator. The combined exit force map and maximal voluntary jettison force data provide a greater understanding of influencing factors associated with training offshore personnel to egress a ditched helicopter.

Enhanced Physics-Based Numerical Schemes for Two Classes of Turbulence Models

We present enhanced physics-based finite element schemes for two families of turbulence models, the models and the Stolz-Adams approximate deconvolution models. These schemes are delicate extensions of a method created for the Navier-Stokes equations in Rebholz (2007), that achieve high physical fidelity by admitting balances of both energy and helicity that match the true physics. The schemes' development requires carefully chosen discrete curl, discrete Laplacian, and discrete filtering operators, in order to permit the necessary differential operator commutations.

Demonstration of a Teamwork Skills Training Program for the Dynamic Targeting Cell

The Dynamic Targeting Cell (DTC) is responsible for prosecuting time-sensitive, dynamic, and emerging targets in the global war on terror. Many DTC tasks impose complex information and resource interdependencies that must be resolved under conditions of high workload. Therefore, DTC operators need effective teamwork skills such as communication, coordination, shared situational awareness, and decision making. The Intervention Methods and Performance Assessment for Crew Training (IMPACT) program is a low physical fidelity, but high psychological fidelity, “training accelerator” that is designed to improve both intra- and inter-team coordination skills. IMPACT training fuses multimedia instruction, practical exercises, instructor feedback, and guided self-reflection using the deliberate practice approach to complex skill acquisition. After completing IMPACT, DTC trainees will be able to “hit the ground running” immediately upon entering a high physical fidelity training simulation or combat exercise.