Sample records for simulated critical loads

  1. Simulation of Mechanical Behavior and Damage of a Large Composite Wind Turbine Blade under Critical Loads (United States)

    Tarfaoui, M.; Nachtane, M.; Khadimallah, H.; Saifaoui, D.


    Issues such as energy generation/transmission and greenhouse gas emissions are the two energy problems we face today. In this context, renewable energy sources are a necessary part of the solution essentially winds power, which is one of the most profitable sources of competition with new fossil energy facilities. This paper present the simulation of mechanical behavior and damage of a 48 m composite wind turbine blade under critical wind loads. The finite element analysis was performed by using ABAQUS code to predict the most critical damage behavior and to apprehend and obtain knowledge of the complex structural behavior of wind turbine blades. The approach developed based on the nonlinear FE analysis using mean values for the material properties and the failure criteria of Tsai-Hill to predict failure modes in large structures and to identify the sensitive zones.

  2. Critical Axial Load

    Directory of Open Access Journals (Sweden)

    Walt Wells


    Full Text Available Our objective in this paper is to solve a second order differential equation for a long, simply supported column member subjected to a lateral axial load using Heun's numerical method. We will use the solution to find the critical load at which the column member will fail due to buckling. We will calculate this load using Euler's derived analytical approach for an exact solution, as well as Euler's Numerical Method. We will then compare the three calculated values to see how much they deviate from one another. During the critical load calculation, it will be necessary to calculate the moment of inertia for the column member.

  3. Empirical and simulated critical loads for nitrogen deposition in California mixed conifer forests (United States)

    M.E. Fenn; S. Jovan; F. Yuan; L. Geiser; T. Meixner; B.S. Gimeno


    Empirical critical loads (CL) for N deposition were determined from changes in epiphytic lichen communities, elevated NO3 leaching in streamwater, and reduced fine root biomass in ponderosa pine (Pinus ponderosa Dougl. ex Laws.) at sites with varying N deposition. The CL for lichen community impacts of 3.1 kg ha-1 year


    LSPC is the Loading Simulation Program in C++, a watershed modeling system that includes streamlined Hydrologic Simulation Program Fortran (HSPF) algorithms for simulating hydrology, sediment, and general water quality


    U.S. Environmental Protection Agency — LSPC is the Loading Simulation Program in C++, a watershed modeling system that includes streamlined Hydrologic Simulation Program Fortran (HSPF) algorithms for...

  6. Critical loads - assessment of uncertainty

    Energy Technology Data Exchange (ETDEWEB)

    Barkman, A.


    The effects of data uncertainty in applications of the critical loads concept were investigated on different spatial resolutions in Sweden and northern Czech Republic. Critical loads of acidity (CL) were calculated for Sweden using the biogeochemical model PROFILE. Three methods with different structural complexity were used to estimate the adverse effects of S0{sub 2} concentrations in northern Czech Republic. Data uncertainties in the calculated critical loads/levels and exceedances (EX) were assessed using Monte Carlo simulations. Uncertainties within cumulative distribution functions (CDF) were aggregated by accounting for the overlap between site specific confidence intervals. Aggregation of data uncertainties within CDFs resulted in lower CL and higher EX best estimates in comparison with percentiles represented by individual sites. Data uncertainties were consequently found to advocate larger deposition reductions to achieve non-exceedance based on low critical loads estimates on 150 x 150 km resolution. Input data were found to impair the level of differentiation between geographical units at all investigated resolutions. Aggregation of data uncertainty within CDFs involved more constrained confidence intervals for a given percentile. Differentiation as well as identification of grid cells on 150 x 150 km resolution subjected to EX was generally improved. Calculation of the probability of EX was shown to preserve the possibility to differentiate between geographical units. Re-aggregation of the 95%-ile EX on 50 x 50 km resolution generally increased the confidence interval for each percentile. Significant relationships were found between forest decline and the three methods addressing risks induced by S0{sub 2} concentrations. Modifying S0{sub 2} concentrations by accounting for the length of the vegetation period was found to constitute the most useful trade-off between structural complexity, data availability and effects of data uncertainty. Data

  7. Load flow analysis using decoupled fuzzy load flow under critical ...

    African Journals Online (AJOL)


    The conventional load flow methods like Newton-Raphson load flow (NRLF), Fast Decoupled load flow (FDLF) provide poor performance under critical conditions such as high R/X ratio, heavily loading condition etc. Exploiting the decoupling properties of power system, reliable fuzzy load flow is developed to overcome the ...

  8. Critical loads of heavy metals for soils

    NARCIS (Netherlands)

    Vries, de W.; Groenenberg, J.E.; Lofts, S.; Tipping, E.; Posch, M.


    To enable a precautionary risk assessment for future inputs of metals, steady-state methods have been developed to assess critical loads of metals avoiding long-term risks to food quality and eco-toxicological effects on organisms in soils and surface waters. A critical load for metals equals the

  9. Aircraft ditching loads simulation tool


    Bonanni, A.; Vandewaeter, L.; Havill, C.; Kanyoo, P.; Taunton, D.J.; Blake, J.I.R.; Cropper, E.; Hancock, S.


    The present work presents a novel methodology developed for calculating the steady loads acting on aircraft structures in the event of ditching in water. It represents the preliminary result of Stirling Dynamics as part of a NATEP research project. The overall objective of the project is to expand the capabilities of the Stirling Dynamics proprietary software SD-GLOAD (originally designed for ground and crash loads dynamic simulations) to aircraft ditching simulations. The methodology present...

  10. Mapping of Critical Loads and Critical Load Exceedances in the Killarney Provincial Park, Ontario, Canada


    Hindar, A.; Henriksen, A.


    Calculations of critical loads for inputs of strong acids to lakes and exceedances of critical load can be a useful tool for the management of polluted areas. In Sudbury, Canada, large emissions of sulfur dioxide have resulted in widespread lake acidification in parts of northeastern Canada. Due to its vicinity to Sudbury, extensive lake acidification and fish loss has occurred in the Killarney Provincial Park. We have linked measured water quality to critical loads and strong acid deposition...

  11. Critical Buckling Load on Large Spherical Shells

    DEFF Research Database (Denmark)

    Wedellsborg, B. W.


    Approximate evaluation for watertanks, hortonspheres, vapor containers, containment vessels for nuclear reactors, and so forth, has been computed, taking into account out-of-roundness and local flattened areas; graphs have been plotted giving critical buckling load as function of maximum radial...

  12. The critical shear load of rectangular plates (United States)

    Seydel, Edgar


    This report gives formulas for analyzing the critical shear load of a simply supported square, isotropic (simple flat plate), or orthogonal anisotropic plate (a plate in which the rigidity in two directions perpendicular to each other is different, i.e. plywood or corrugated sheet), these formulas, although arrived at by approximation method, seem to agree fairly well with experimental results.

  13. Simulation of Stochastic Loads for Fatigue Experiments

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Brincker, Rune

    A simple direct simulation method for stochastic fatigue load generation is described in this paper. The simulation method is based on the assumption that only the peaks of the load process significantly affect the fatigue life. The method requires the conditional distribution functions of load...... second using an IBM PC. Finally the proposed simulation method for fatigue load generation is tested by comparing some fatigue damage measures obtained by the simulation methods....

  14. Research of Impact Load in Large Electrohydraulic Load Simulator

    Directory of Open Access Journals (Sweden)

    Yongguang Liu


    Full Text Available The stronger impact load will appear in the initial phase when the large electric cylinder is tested in the hardware-in-loop simulation. In this paper, the mathematical model is built based on AMESim, and then the reason of the impact load is investigated through analyzing the changing tendency of parameters in the simulation results. The inhibition methods of impact load are presented according to the structural invariability principle and applied to the actual system. The final experimental result indicates that the impact load is inhibited, which provides a good experimental condition for the electric cylinder and promotes the study of large load simulator.

  15. Modelling and Simulation of Wave Loads

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Thoft-Christensen, Palle


    A simple model of the wave load on stender members of offshore structures is described . The wave elevation of the sea stateis modelled by a stationary Gaussian process. A new procedure to simulate realizations of the wave loads is developed. The simulation method assumes that the wave particle...

  16. Simulation of Stochastic Loads for Fatigue Experiments

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Brincker, Rune


    A simple direct simulation method for stochastic fatigue-load generation is described in this paper. The simulation method is based on the assumption that only the peaks of the load process significantly affect the fatigue life. The method requires the conditional distribution functions of load...... process by a Markov process. Two different spectra from two tubular joints in an offshore structure (one narrow banded and one wide banded) are considered in an example. The results show that the simple direct method is quite efficient and results in a simulation speed of about 3000 load cycles per second...... ranges given the last peak values. Analytical estimates of these distribution functions are presented in the paper and compared with estimates based on a more accurate simulation method. In the more accurate simulation method samples at equidistant times are generated by approximating the stochastic load...

  17. Probabilistic Load Models for Simulating the Impact of Load Management

    DEFF Research Database (Denmark)

    Chen, Peiyuan; Bak-Jensen, Birgitte; Chen, Zhe


    to simulate the impact of load management. The joint-normal model is superior in modeling the tail region of the hourly load distribution and implementing the change of hourly standard deviation. Whereas the AR(12) model requires much less parameter and is superior in modeling the autocorrelation......This paper analyzes a distribution system load time series through autocorrelation coefficient, power spectral density, probabilistic distribution and quantile value. Two probabilistic load models, i.e. the joint-normal model and the autoregressive model of order 12 (AR(12)), are proposed....... It is concluded that the AR(12) model is favored with limited measurement data and that the joint-normal model may provide better results with a large data set. Both models can be applied in general to model load time series and used in time-sequential simulation of distribution system planning....

  18. Modelling and Simulation of Wave Loads

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Thoft-Christensen, Palle

    A simple model of the wave load on slender members of offshore structures is described. The wave elevation of the sea state is modelled by a stationary Gaussian process. A new procedure to simulate realizations of the wave loads is developed. The simulation method assumes that the wave particle...... velocity can be approximated by a Gaussian Markov process. Known approximate results for the first-passage density or equivalently, the distribution of the extremes of wave loads are presented and compared with rather precise simulation results. It is demonstrated that the approximate results...

  19. Load flow analysis using decoupled fuzzy load flow under critical ...

    African Journals Online (AJOL)


    mismatch and summation of power mismatches are taken as two inputs for fuzzy logic controller. Considering magnitude of power mismatch and sign of power mismatch, new 25 fuzzy rules are created from two sets of inputs. The proposed Decoupled. Fuzzy Load Flow (FDLF) is applied to IEEE 14 bus, IEEE 30 bus, IEEE ...

  20. Deposition, critical loads, and exceedances for 1800-2025 (United States)

    U.S. Environmental Protection Agency — This data includes gridded estimates of: (1) decadally averaged total N and S deposition for the conterminous US from 1800-2025, (2) critical loads from the National...

  1. Efficient critical design load case identification for floating offshore wind turbines with a reduced nonlinear model (United States)

    Matha, Denis; Sandner, Frank; Schlipf, David


    Design verification of wind turbines is performed by simulation of design load cases (DLC) defined in the IEC 61400-1 and -3 standards or equivalent guidelines. Due to the resulting large number of necessary load simulations, here a method is presented to reduce the computational effort for DLC simulations significantly by introducing a reduced nonlinear model and simplified hydro- and aerodynamics. The advantage of the formulation is that the nonlinear ODE system only contains basic mathematic operations and no iterations or internal loops which makes it very computationally efficient. Global turbine extreme and fatigue loads such as rotor thrust, tower base bending moment and mooring line tension, as well as platform motions are outputs of the model. They can be used to identify critical and less critical load situations to be then analysed with a higher fidelity tool and so speed up the design process. Results from these reduced model DLC simulations are presented and compared to higher fidelity models. Results in frequency and time domain as well as extreme and fatigue load predictions demonstrate that good agreement between the reduced and advanced model is achieved, allowing to efficiently exclude less critical DLC simulations, and to identify the most critical subset of cases for a given design. Additionally, the model is applicable for brute force optimization of floater control system parameters.

  2. Potential nitrogen critical loads for northern Great Plains grassland vegetation (United States)

    Symstad, Amy J.; Smith, Anine T.; Newton, Wesley E.; Knapp, Alan K.


    The National Park Service is concerned that increasing atmospheric nitrogen deposition caused by fossil fuel combustion and agricultural activities could adversely affect the northern Great Plains (NGP) ecosystems in its trust. The critical load concept facilitates communication between scientists and policy makers or land managers by translating the complex effects of air pollution on ecosystems into concrete numbers that can be used to inform air quality targets. A critical load is the exposure level below which significant harmful effects on sensitive elements of the environment do not occur. A recent review of the literature suggested that the nitrogen critical load for Great Plains vegetation is 10-25 kg N/ha/yr. For comparison, current atmospheric nitrogen deposition in NGP National Park Service (NPS) units ranges from ~4 kg N/ha/yr in the west to ~13 kg N/ha/yr in the east. The suggested critical load, however, was derived from studies far outside of the NGP, and from experiments investigating nitrogen loads substantially higher than current atmospheric deposition in the region.Therefore, to better determine the nitrogen critical load for sensitive elements in NGP parks, we conducted a four-year field experiment in three northern Great Plains vegetation types at Badlands and Wind Cave National Parks. The vegetation types were chosen because of their importance in NGP parks, their expected sensitivity to nitrogen addition, and to span a range of natural fertility. In the experiment, we added nitrogen at rates ranging from below current atmospheric deposition (2.5 kg N/ha/yr) to far above those levels but commensurate with earlier experiments (100 kg N/ha/yr). We measured the response of a variety of vegetation and soil characteristics shown to be sensitive to nitrogen addition in other studies, including plant biomass production, plant tissue nitrogen concentration, plant species richness and composition, non-native species abundance, and soil inorganic

  3. The critical loads and levels approach for nitrogen (United States)

    T.A. Clair; T. Blett; J. Aherne; M.P.M. Aidar; R. Artz; W.J. Bealey; W. Budd; J.N. Cape; C.J. Curtis; L. Duan; M.E. Fenn; P. Groffman; R. Haeuber; J.R. Hall; J.-P. Hettelingh; D. López-Hernández; B. Mathieson; L. Pardo; M. Posch; R.V. Pouyat; T. Spranger; H. Sverdrup; H. van Dobben; A. van Hinsberg


    This chapter reports the findings of a Working Group to review the critical loads (CLs) and levels approach for nitrogen (N). The three main approaches to estimating CLs are empirical, mass balance and dynamic modelling. Examples are given of recent developments in Europe, North America and Asia and it is concluded that other countries should be encouraged to develop...

  4. Wind simulation for extreme and fatigue loads

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, M.; Larsen, G.C.; Mann, J.; Ott, S.; Hansen, K.S.; Pedersen, B.J.


    Measurements of atmospheric turbulence have been studied and found to deviate from a Gaussian process, in particular regarding the velocity increments over small time steps, where the tails of the pdf are exponential rather than Gaussian. Principles for extreme event counting and the occurrence of cascading events are presented. Empirical extreme statistics agree with Rices exceedence theory, when it is assumed that the velocity and its time derivative are independent. Prediction based on the assumption that the velocity is a Gaussian process underpredicts the rate of occurrence of extreme events by many orders of magnitude, mainly because the measured pdf is non-Gaussian. Methods for simulation of turbulent signals have been developed and their computational efficiency are considered. The methods are applicable for multiple processes with individual spectra and probability distributions. Non-Gaussian processes are simulated by the correlation-distortion method. Non-stationary processes are obtained by Bezier interpolation between a set of stationary simulations with identical random seeds. Simulation of systems with some signals available is enabled by conditional statistics. A versatile method for simulation of extreme events has been developed. This will generate gusts, velocity jumps, extreme velocity shears, and sudden changes of wind direction. Gusts may be prescribed with a specified ensemble average shape, and it is possible to detect the critical gust shape for a given construction. The problem is formulated as the variational problem of finding the most probable adjustment of a standard simulation of a stationary Gaussian process subject to relevant event conditions, which are formulated as linear combination of points in the realization. The method is generalized for multiple correlated series, multiple simultaneous conditions, and 3D fields of all velocity components. Generalization are presented for a single non-Gaussian process subject to relatively

  5. Critical loads and excess loads of cadmium, copper and lead for European forest soils

    NARCIS (Netherlands)

    Reinds, G.J.; Bril, J.; Vries, de W.; Groenenberg, J.E.; Breeuwsma, A.


    Recently, concern has arisen about the impact of the dispersion of heavy metals in Europe. Therefore, a study (ESQUAD) was initiated to assess critical loads and steady-state concentrations of cadmium, copper and lead for European forest soils. The calculation methods used strongly resemble those

  6. Critical plane approach to multiaxial variable amplitude fatigue loading

    Directory of Open Access Journals (Sweden)

    Yingyu Wang


    Full Text Available A new critical plane approach based on the modified Manson-Coffin curve method (MMCCM is presented in this paper for predicting fatigue lifetime under variable amplitude (VA multiaxial fatigue loading. The critical plane is assumed to coincide with that material plane experiencing the maximum variance of the resolved shear strain. Fatigue damage is hypothesized to be a function of both the amplitude of the resolved shear strain and the so-called critical plane stress ratio. The latter quantity depends on the mean value and the variance of the stress perpendicular to the critical plane as well as on the variance of the shear stress resolved along the direction experiencing the maximum variance of the resolved shear strain. Load cycles are counted from the resolved shear strain time history by using the classic rain flow counting method. Palmgren-Miner’s linear damage rule is applied to estimate cumulative fatigue damage. The accuracy and reliability of the proposed approach is checked by using several experimental data taken from the literature. The estimated fatigue lives based on the new approach are seen to be in sound agreement with the experimental results.

  7. Mass balance approaches to assess critical loads and target loads of heavy metals for terrestrial and aquatic ecosystems

    NARCIS (Netherlands)

    Vries, de W.; Groenenberg, J.E.; Posch, M.


    Critical loads of heavy metals address not only ecotoxicological effects on organisms in soils and surface waters, but also food quality in view of public health. A critical load for metals is the load resulting at steady state in a metal concentration in a compartment (e.g. soil solution, surface

  8. Eutrophic lichens respond to multiple forms of N: implications for critical levels and critical loads research (United States)

    Sarah Jovan; Jennifer Riddell; Pamela E Padgett; Thomas Nash


    Epiphytic lichen communities are highly sensitive to excess nitrogen (N), which causes the replacement of native floras by N-tolerant, ‘‘weedy’’ eutrophic species. This shift is commonly used as the indicator of ecosystem ‘‘harm’’ in studies developing empirical critical levels (CLE) for ammonia (NH3) and critical loads (CLO) for N. To be most...

  9. A second simulated criticality accident dosimetry experiment

    CERN Document Server

    Adams, N


    This experiment was undertaken to facilitate training in criticality dose assessment by UKAEA and BNFL establishments with potential criticality hazards. Personal dosemeters, coins, samples of hair, etc. supplied by the seven participating establishments were attached to a man-phantom filled with a solution of sodium nitrate (simulating 'body-sodium'), and exposed to a burst of radiation from the AWRE pulsed reactor VIPER. The neutron and photon doses were each several hundred rads. Participants made two sets of dose assessments. The first, made solely from the evidence of their routine dosemeters the activation of body-sodium and standard monitoring data, simulated the initial dose assessment that would be made before the circumstances of a real incident were established. The second was made when the position and orientation of the phantom relative to the reactor and the shielding (20 cm of copper) between the reactor core and the phantom were disclosed. Neutron and photon dose assessments for comparison wit...

  10. Heat-load simulator for heat sink design (United States)

    Dunleavy, A. M.; Vaughn, T. J.


    Heat-load simulator is fabricated from 1/4-inch aluminum plate with a contact surface equal in dimensions and configuration to those of the electronic installation. The method controls thermal output to simulate actual electronic component thermal output.


    Directory of Open Access Journals (Sweden)

    T. I. Aliev


    Full Text Available The article presents research results of random number generators (RNG influence on simulation accuracy of high-loaded queuing systems in the GPSS World simulation system. It is shown that for certain combinations of RNGs, called problem generators, the inaccuracy of the simulation results of highly loaded systems may reach tens of percent. The analysis of problem combinations revealed factors causing high level of inaccuracy in simulation results.

  12. Long-term modelling of nitrogen turnover and critical loads in a forested catchment using the INCA model

    Directory of Open Access Journals (Sweden)

    J.-J. Langusch


    Full Text Available Many forest ecosystems in Central Europe have reached the status of N saturation due to chronically high N deposition. In consequence, the NO3 leaching into ground- and surface waters is often substantial. Critical loads have been defined to abate the negative consequences of the NO3 leaching such as soil acidification and nutrient losses. The steady state mass balance method is normally used to calculate critical loads for N deposition in forest ecosystems. However, the steady state mass balance approach is limited because it does not take into account hydrology and the time until the steady state is reached. The aim of this study was to test the suitability of another approach: the dynamic model INCA (Integrated Nitrogen Model for European Catchments. Long-term effects of changing N deposition and critical loads for N were simulated using INCA for the Lehstenbach spruce catchment (Fichtelgebirge, NE Bavaria, Germany under different hydrological conditions. Long-term scenarios of either increasing or decreasing N deposition indicated that, in this catchment, the response of nitrate concentrations in runoff to changing N deposition is buffered by a large groundwater reservoir. The critical load simulated by the INCA model with respect to a nitrate concentration of 0.4 mg N l–1 as threshold value in runoff was 9.7 kg N ha–1yr–1 compared to 10 kg ha–1yr–1 for the steady state model. Under conditions of lower precipitation (520 mm the resulting critical load was 7.7 kg N ha–1yr–1 , suggesting the necessity to account for different hydrological conditions when calculating critical loads. The INCA model seems to be suitable to calculate critical loads for N in forested catchments under varying hydrological conditions e.g. as a consequence of climate change. Keywords: forest ecosystem, N saturation, critical load, modelling, long-term scenario, nitrate leaching, critical loads reduction, INCA

  13. Simulating liquid loading in gas wells

    NARCIS (Netherlands)

    Schiferli, W.; Belfroid, S.P.C.; Savenko, S.; Veeken, C.A.M.; Hu, B.


    This paper describes work performed by the authors over the last several years to better understand the factors affecting the onset of liquid loading. To further improve the prediction of onset of liquid loading, efforts were undertaken to better model the process. Dedicated codes as well as a

  14. Measuring cognitive load: performance, mental effort and simulation task complexity. (United States)

    Haji, Faizal A; Rojas, David; Childs, Ruth; de Ribaupierre, Sandrine; Dubrowski, Adam


    Interest in applying cognitive load theory in health care simulation is growing. This line of inquiry requires measures that are sensitive to changes in cognitive load arising from different instructional designs. Recently, mental effort ratings and secondary task performance have shown promise as measures of cognitive load in health care simulation. We investigate the sensitivity of these measures to predicted differences in intrinsic load arising from variations in task complexity and learner expertise during simulation-based surgical skills training. We randomly assigned 28 novice medical students to simulation training on a simple or complex surgical knot-tying task. Participants completed 13 practice trials, interspersed with computer-based video instruction. On trials 1, 5, 9 and 13, knot-tying performance was assessed using time and movement efficiency measures, and cognitive load was assessed using subjective rating of mental effort (SRME) and simple reaction time (SRT) on a vibrotactile stimulus-monitoring secondary task. Significant improvements in knot-tying performance (F(1.04,24.95)  = 41.1, p cognitive load (F(2.3,58.5)  = 57.7, p cognitive load during skills training. Mental effort ratings are also sensitive to small differences in intrinsic load arising from variations in the physical complexity of a simulation task. The complementary nature of these subjective and objective measures suggests their combined use is advantageous in simulation instructional design research. © 2015 John Wiley & Sons Ltd.

  15. Evaluation of approaches to calculate critical metal loads for forest soils

    NARCIS (Netherlands)

    Vries, de W.; Groenenberg, J.E.


    This paper evaluates approaches to calculate acceptable loads for metal deposition to forest ecosystems, distinguishing between critical loads, stand-still loads and target loads. We also evaluated the influence of including the biochemical metal cycle on the calculated loads. Differences are

  16. Exceedance of critical loads and of critical limits impacts tree nutrition across Europe

    DEFF Research Database (Denmark)

    Waldner, P.; Thimonier, A.; Graf Pannatier, E.


    are not expected to occur. Aims We explored the relationship between the exceedance of critical loads and inorganic nitrogen concentration, the base cation to aluminium ratio in soil solutions, as well as the nutritional status of trees. Methods We used recent data describing deposition, elemental concentrations....... Conclusion The findings support the hypothesis that elevated nitrogen and sulphur deposition can lead to imbalances in tree nutrition....

  17. Simulation of cumulative damage associated with long term cyclic loading using a multi-level strain accommodating loading protocol. (United States)

    Aboushelib, Moustafa Nabil


    To assess step by step the associated cumulative damage introduced in zirconia veneered restorations after long term cyclic loading using a new multi-level strain accommodating loading protocol. 40 zirconia veneered crowns received thermal and cyclic loading (3.5 million cycles at maximum load of 25 kg representing 70% of the critical load of the veneer ceramic). The used loading protocol allowed for reproduction of the combined damping action of the periodontal ligament, food substance, jaw deformation, and free movement of the mandibular joint. Speed of load application and release was obtained from the chewing cycle of adult patients. Principles of fractographic analysis were used to study the behavior and origin of critical crack and associated structural damage. The multi-level strain damping effect prevented generation of cone cracks and contact damage under the loading indenter commonly associated with fracture strength tests. 29 specimens (73%) survived 3.5 million cycles without fracture, 9 specimens (22%) demonstrated cohesive fracture of the veneer ceramic and limited axial fracture of the framework was observed in two specimens (5%). Of all fractured specimens, 2 restorations (5%) failed after 500,000 cycles while the rest survived at least 3 million cycles before fracture was observed. Fractographic analysis revealed initial wear and abrasion below the loading area, subsurface micro-cracking of the glass matrix followed by slow crack growth that traveled in a stepping pattern till deflection at zirconia veneer interface. Cyclic loading using multi-level strain accommodating model can reproduce clinical failure. With exception to manufacturing errors, zirconia veneered restoration survived a simulated 7-year service time without fracture. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  18. Calculation of critical loads for cadmium, lead and mercury; background document to a mapping manual on critical loads of cadmium, lead and mercury

    NARCIS (Netherlands)

    Vries, de W.; Schütze, G.; Lofts, S.; Tipping, E.; Meili, M.; Römkens, P.F.A.M.; Groenenberg, J.E.


    This report on heavy metals provides up-to-date methodologies to derive critical loads for the heavy metals cadmium (Cd), lead (Pb) and mercury (Hg) for both terrestrial and aquatic ecosystems. It presents background information to a Manual on Critical Loads for those metals. Focus is given to the

  19. Cognitive Load Theory for the Design of Medical Simulations. (United States)

    Fraser, Kristin L; Ayres, Paul; Sweller, John


    Simulation-based education (SBE) has emerged as an effective and important tool for medical educators, but research about how to optimize training with simulators is in its infancy. It is often difficult to generalize results from experiments on instructional design issues in simulation because of the heterogeneity of learner groups, teaching methods, and rapidly changing technologies. We have found that cognitive load theory is highly relevant to teaching in the simulation laboratory and a useful conceptual framework to reference when designing or researching simulation-based education. Herein, we briefly describe cognitive load theory, its grounding in our current understanding of cognitive architecture, and the evidence supporting it. We focus our discussion on a few well-established cognitive load effects with examples from simulation training and recommend some instructional applications with theoretical potential to improve learning outcomes.

  20. Effect of Eccentricity of Load on Critical Force of Thin-Walled Columns CFRP

    Directory of Open Access Journals (Sweden)

    Pawel Wysmulski


    Full Text Available The subject of study was a thin-walled C-section made of carbon fiber reinforced polymer (CFRP. Column was subjected to eccentric compression in the established direction. In the computer simulation, the boundary conditions were assumed in the form of articulated support of the sections of the column. Particular studies included an analysis of the effects of eccentricity on the critical force value. The research was conducted using two independent research methods: numerical and experimental. Numerical simulations were done using the finite element method using the advanced system Abaqus®. The high sensitivity of the critical force value corresponding to the local buckling of the channel section to the load eccentricity was demonstrated.

  1. Simulation of load traffic and steeped speed control of conveyor (United States)

    Reutov, A. A.


    The article examines the possibilities of the step control simulation of conveyor speed within Mathcad, Simulink, Stateflow software. To check the efficiency of the control algorithms and to more accurately determine the characteristics of the control system, it is necessary to simulate the process of speed control with real values of traffic for a work shift or for a day. For evaluating the belt workload and absence of spillage it is necessary to use empirical values of load flow in a shorter period of time. The analytical formulas for optimal speed step values were received using empirical values of load. The simulation checks acceptability of an algorithm, determines optimal parameters of regulation corresponding to load flow characteristics. The average speed and the number of speed switching during simulation are admitted as criteria of regulation efficiency. The simulation example within Mathcad software is implemented. The average conveyor speed decreases essentially by two-step and three-step control. A further increase in the number of regulatory steps decreases average speed insignificantly but considerably increases the intensity of the speed switching. Incremental algorithm of speed regulation uses different number of stages for growing and reducing load traffic. This algorithm allows smooth control of the conveyor speed changes with monotonic variation of the load flow. The load flow oscillation leads to an unjustified increase or decrease of speed. Work results can be applied at the design of belt conveyors with adjustable drives.

  2. Cognitive load predicts point-of-care ultrasound simulator performance. (United States)

    Aldekhyl, Sara; Cavalcanti, Rodrigo B; Naismith, Laura M


    The ability to maintain good performance with low cognitive load is an important marker of expertise. Incorporating cognitive load measurements in the context of simulation training may help to inform judgements of competence. This exploratory study investigated relationships between demographic markers of expertise, cognitive load measures, and simulator performance in the context of point-of-care ultrasonography. Twenty-nine medical trainees and clinicians at the University of Toronto with a range of clinical ultrasound experience were recruited. Participants answered a demographic questionnaire then used an ultrasound simulator to perform targeted scanning tasks based on clinical vignettes. Participants were scored on their ability to both acquire and interpret ultrasound images. Cognitive load measures included participant self-report, eye-based physiological indices, and behavioural measures. Data were analyzed using a multilevel linear modelling approach, wherein observations were clustered by participants. Experienced participants outperformed novice participants on ultrasound image acquisition. Ultrasound image interpretation was comparable between the two groups. Ultrasound image acquisition performance was predicted by level of training, prior ultrasound training, and cognitive load. There was significant convergence between cognitive load measurement techniques. A marginal model of ultrasound image acquisition performance including prior ultrasound training and cognitive load as fixed effects provided the best overall fit for the observed data. In this proof-of-principle study, the combination of demographic and cognitive load measures provided more sensitive metrics to predict ultrasound simulator performance. Performance assessments which include cognitive load can help differentiate between levels of expertise in simulation environments, and may serve as better predictors of skill transfer to clinical practice.

  3. Wind Simulation for Extreme and Fatigue Loads

    DEFF Research Database (Denmark)

    Nielsen, Morten; Larsen, Gunner Chr.; Mann, Jakob


    by many orders of magnitude, mainly because the measured pdf is non-Gaussian. Methods for simulation of turbulent signals have been developed and theircomputational efficiency are considered. The methods are applicable for multiple processes with individual spectra and probability distributions. Non......Measurements of atmospheric turbulence have been studied and found to deviate from a Gaussian process, in particular regarding the velocity increments over small time steps, where the tails of the pdf are exponential rather than Gaussian. Principles forextreme event counting and the occurrence...... is formulated as the variational problem of finding the most probable adjustment of a standard simulation of a stationary Gaussian process subject to relevant event conditions, which are formulated as linear combination of pointsin the realization. The method is generalized for multiple correlated series...

  4. Dynamic Fracture Simulations of Explosively Loaded Cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Arthur, Carly W. [Univ. of California, Davis, CA (United States). Dept. of Civil and Environmental Engineering; Goto, D. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)


    This report documents the modeling results of high explosive experiments investigating dynamic fracture of steel (AerMet® 100 alloy) cylinders. The experiments were conducted at Lawrence Livermore National Laboratory (LLNL) during 2007 to 2008 [10]. A principal objective of this study was to gain an understanding of dynamic material failure through the analysis of hydrodynamic computer code simulations. Two-dimensional and three-dimensional computational cylinder models were analyzed using the ALE3D multi-physics computer code.

  5. Critical acidity loads in France; Charges critiques d`acidite en France

    Energy Technology Data Exchange (ETDEWEB)

    Probst, A.; Party, J.P.; Fevrier, C. [Centre de Geochimie de la Surface (UPR 06251 du CNRS), 67 - Strasbourg (France); Dambrine, E. [Centre de Recherches Forestieres, INRA, 45 - Orleans (France); Thomas, A.L.; King, D. [Institut National de Recherches Agronomique (INRA), 45 - ORDON (France); Stussi, J.M. [Centre National de la Recherche Scientifique (CNRS), 54 - Vandoeuvre-les-Nancy (France)


    Based on results from several systematic forest and surface water monitoring programs, carried out in various parts of France as well as in Europe, acidity critical loads have been calculated for soils and surface waters; critical loads are presented for water and soils in crystalline mountainous regions such as Ardennes, Vosges and Massif Central; links with geochemistry, ecosystems and types of trees are discussed and perspectives are given for the calculation of acid and nitrogen critical loads on the whole France

  6. Direct contribution of axial impact compressive load to anterior tibial load during simulated ski landing impact. (United States)

    Yeow, C H; Lee, P V S; Goh, J C H


    Anterior tibial loading is a major factor involved in the anterior cruciate ligament (ACL) injury mechanism during ski impact landing. We sought to investigate the direct contribution of axial impact compressive load to anterior tibial load during simulated ski landing impact of intact knee joints without quadriceps activation. Twelve porcine knee specimens were procured. Four specimens were used as non-impact control while the remaining eight were mounted onto a material-testing system at 70 degrees flexion and subjected to simulated landing impact, which was successively repeated with incremental actuator displacement. Four specimens from the impacted group underwent pre-impact MRI for tibial plateau angle measurements while the other four were subjected to histology and microCT for cartilage morphology and volume assessment. The tibial plateau angles ranged from 29.4 to 38.8 degrees . There was a moderate linear relationship (Y=0.16X; R(2)=0.64; p<0.001) between peak axial impact compressive load (Y) and peak anterior tibial load (X). The anterior and posterior regions in the impacted group sustained surface cartilage fraying, superficial clefts and tidemark disruption, compared to the control group. MicroCT scans displayed visible cartilage deformation for both anterior and posterior regions in the impacted group. Due to the tibial plateau angle, increased axial impact compressive load can directly elevate anterior tibial load and hence contribute to ACL failure during simulated landing impact. Axial impact compressive load resulted in shear cartilage damage along anterior-posterior tibial plateau regions, due to its contribution to anterior tibial loading. This mechanism plays an important role in elevating ACL stress and cartilage deformation during impact landing. Copyright 2009 Elsevier Ltd. All rights reserved.

  7. Emotion, cognitive load and learning outcomes during simulation training. (United States)

    Fraser, Kristin; Ma, Irene; Teteris, Elise; Baxter, Heather; Wright, Bruce; McLaughlin, Kevin


    Simulation training has emerged as an effective way to complement clinical training of medical students. Yet outcomes from simulation training must be considered suboptimal when 25-30% of students fail to recognise a cardiac murmur on which they were trained 1 hour previously. There are several possible explanations for failure to improve following simulation training, which include the impact of heightened emotions on learning and cognitive overload caused by interactivity with high-fidelity simulators. This study was conducted to assess emotion during simulation training and to explore the relationships between emotion and cognitive load, and diagnostic performance. We trained 84 Year 1 medical students on a scenario of chest pain caused by symptomatic aortic stenosis. After training, students were asked to rate their emotional state and cognitive load. We then provided training on a dyspnoea scenario before asking participants to diagnose the murmur in which they had been trained (aortic stenosis) and a novel murmur (mitral regurgitation). We used factor analysis to identify the principal components of emotion, and then studied the associations between these components of emotion and cognitive load and diagnostic performance. We identified two principal components of emotion, which we felt represented invigoration and tranquillity. Both of these were associated with cognitive load with adjusted regression coefficients of 0.63 (95% confidence interval [CI] 0.28-0.99; p = 0.001) and - 0.44 (95% CI - 0.77 to - 0.10; p = 0.009), respectively. We found a significant negative association between cognitive load and the odds of subsequently identifying the trained murmur (odds ratio 0.27, 95% CI 0.11-0.67; p = 0.004). We found that increased invigoration and reduced tranquillity during simulation training were associated with increased cognitive load, and that the likelihood of correctly identifying a trained murmur declined with increasing cognitive load. Further

  8. Simulation of plasma loading of high-pressure RF cavities

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Kwangmin [Brookhaven; Samulyak, Roman [SUNY, Stony Brook; Yonehara, Katsuya [Fermilab; Freemire, Ben [Northern Illinois U.


    Muon beam-induced plasma loading of radio-frequency (RF) cavities filled with high pressure hydrogen gas with 1% dry air dopant has been studied via numerical simulations. The electromagnetic code SPACE, that resolves relevant atomic physics processes, including ionization by the muon beam, electron attachment to dopant molecules, and electron-ion and ion-ion recombination, has been used. Simulations studies have been performed in the range of parameters typical for practical muon cooling channels.

  9. Avalanche transmission and critical behaviour in load-bearing ...

    Indian Academy of Sciences (India)

    The strength and stability properties of hierarchical load-bearing networks and their strengthened variants have been discussed in a recent work. Here, we study the avalanche time distributions on these load-bearing networks. The avalanche time distributions of the V-lattice, a unique realization of the networks, show ...

  10. Designing Nursing Simulation Clinical Experiences to Promote Critical Inquiry (United States)

    Beattie, Bev; Koroll, Donna; Price, Susan


    The use of high fidelity simulation (HFS) learning opportunities in nursing education has received increased attention in the literature. This article describes the design of a systematic framework used to promote critical inquiry and provide meaningful simulation clinical experiences for second year nursing students. Critical inquiry, as defined…

  11. Critical loads of cadmium, lead and mercury and their exceedances in Europe

    NARCIS (Netherlands)

    Hettelingh, J.P.; Schütze, G.; Vries, de W.; Denier van der Gon, H.A.C.; Ilyin, I.; Reinds, G.J.; Slootweg, J.; Travnikov, O.


    In this chapter information is summarized on the assessment of the risk of impacts of cadmium, lead and mercury emissions and related depositions of these metals, with an emphasis on natural areas in Europe. Depositions are compared to critical loads to identify areas in Europe where critical loads

  12. A conceptual framework: redifining forests soil's critical acid loads under a changing climate (United States)

    Steven G. McNulty; Johnny L. Boggs


    Federal agencies of several nations have or are currently developing guidelines for critical forest soil acid loads. These guidelines are used to establish regulations designed to maintain atmospheric acid inputs below levels shown to damage forests and streams. Traditionally, when the critical soil acid load exceeds the amount of acid that the ecosystem can absorb, it...

  13. Critical loads as a policy tool for protecting ecosystems from the effects of air pollutants (United States)

    Douglas A. Burns; Tamara Blett; Richard Haeuber; Linda H. Pardo


    Framing the effects of air pollutants on ecosystems in terms of a "critical load" provides a meaningful approach for research scientists to communicate policy-relevant science to air-quality policy makers and natural resource managers. A critical-loads approach has been widely used to shape air-pollutant control policy in Europe since the 1980s, yet has only...

  14. Evaluation of estimation methods and base data uncertainties for critical loads of acid deposition in Japan

    NARCIS (Netherlands)

    Shindo, J.; Bregt, A.K.; Hakamata, T.


    A simplified steady-state mass balance model for estimating critical loads was applied to a test area in Japan to evaluate its applicability. Three criteria for acidification limits were used. Mean values and spatial distribution patterns of critical load values calculated by these criteria differed

  15. Load balancing of parallel cell-based blood flow simulations

    NARCIS (Netherlands)

    Alowayyed, S.; Závodszky, G.; Azizi, V.; Hoekstra, A.G.

    The non-homogeneous distribution of computational costs is often challenging to handle in highly parallel applications. Using a methodology based on fractional overheads, we studied the fractional load imbalance overhead in a high-performance biofluid simulation aiming to accurately resolve blood

  16. Monitoring internal load parameters during simulated and official basketball matches. (United States)

    Moreira, Alexandre; McGuigan, Michael R; Arruda, Ademir F s; Freitas, Camila G; Aoki, Marcelo S


    The purpose of this study was to compare the internal load responses (session rating of perceived exertion [RPE] and salivary cortisol) between simulated and official matches (SM and OM). Ten professional basketball players participated in 2 OMs and 2 SMs during the competition season. Subjects provided saliva samples 30 minutes before the prematch warm-up (PRE) and 10 minutes after the end of the match. Session RPE (CR-10 scale) was assessed 30 minutes after each match. The results from the 2-way analysis of variance showed significant differences for post-OM salivary cortisol as compared with pre-OM values (p internal loads, and the results are useful in providing a better understanding of internal loads imposed by basketball training and competitions. The precise monitoring of these responses might help the coaches to plan appropriate loads maximizing recovery and performance.

  17. Maps of critical loads and exceedance for sulfur and nitrogen to forest soils in Norway

    Energy Technology Data Exchange (ETDEWEB)

    Frogner, T.; Wright, R.F.; Cosby, B.J.; Esser, J.M.


    This report uses the dynamic MAGIC (Model of Acidification of Groundwater in Catchments) model to calculate critical loads of sulfur and nitrogen for forest soils in Norway. Inputs include soil survey data, atmospheric deposition data, forest productivity data, and surface water chemistry. Two scenarios for future sulfur deposition are used with two scenarios of nitrogen retention in catchments. The magnitude and patterns of calculated nitrogen critical loads and exceedance differ substantially depending on the scenario chosen for sulfur deposition and nitrogen retention. In the worst case, critical loads for N are low and exceeded in southernmost Norway. In the best case, critical loads for N are high and not exceeded. More information on the processes controlling N retention in forested ecosystems is of utmost importance for the specification of nitrogen critical loads. 25 refs., 14 figs., 1 table

  18. The control algorithm improving performance of electric load simulator (United States)

    Guo, Chenxia; Yang, Ruifeng; Zhang, Peng; Fu, Mengyao


    In order to improve dynamic performance and signal tracking accuracy of electric load simulator, the influence of the moment of inertia, stiffness, friction, gaps and other factors on the system performance were analyzed on the basis of researching the working principle of load simulator in this paper. The PID controller based on Wavelet Neural Network was used to achieve the friction nonlinear compensation, while the gap inverse model was used to compensate the gap nonlinear. The compensation results were simulated by MATLAB software. It was shown that the follow-up performance of sine response curve of the system became better after compensating, the track error was significantly reduced, the accuracy was improved greatly and the system dynamic performance was improved.

  19. Numerical simulation of ice-load induced salt movements (United States)

    Lang, Joerg; Al-Hseinat, Muayyad; Brandes, Christian; Hampel, Andrea; Hübscher, Christian; Winsemann, Jutta


    A correlation between salt structures, glacigenic features and faulting of Pleistocene deposits above salt structures has been recognised in many places of the formerly glaciated areas in northern central Europe and attributed to ice-sheet loading. Conceptual models predict that the load applied by an ice sheet will favour ice-marginal salt rise and obstruct salt rise beneath the ice sheet (e.g., Liszkowski, 1993). To test these models, we simulated the response of salt structures to ice-sheet loading using a 2D finite-element model (ABAQUS). The subsurface geometries used in our models are based on regional geological cross-sections and 2D seismic profiles of salt structures in the Central European Basin System. The model layers represent (i) sedimentary rocks of elastoplastic rheology, (ii) a viscoelastic salt structure and (iii) elastoplastic basement rocks. At the model surface a temporarily and spatially variable pressure simulates ice-sheet loading. All our simulations show a response of salt structures to ice-sheet loading, which strongly depends on the location of the ice margin relative to the salt structure. Salt structures rise in front of the ice margin (up to 4 m), if load is applied to the salt source layer. Beneath an ice sheet salt structures are pushed down (up to 36 m). Much of the subglacial downwards displacement is compensated by a reversal of the movement during ice retreat. The resulting surface displacements are therefore rather low and depend on the spatial and temporal configuration of the ice load (Lang et al., 2014). Permanent deformation is restricted to the model layers above the salt structure, which either have a low yield stress to represent the unconsolidated infill of secondary rim-synclines or are dissected by steeply dipping crestal graben faults. Ice-induced salt movements will reactivate faults above the crests of salt structures, although the resulting displacements will be low due to the repeated reversals of the sense of

  20. Simulator program for load flow calculations and correct switching training; Simulationsprogramm fuer Netzberechnug und Schalttraining

    Energy Technology Data Exchange (ETDEWEB)

    Raschick, H.; Bernhardt, R. [Ingenieur- und Servicegesellschaft fuer Energie und Umwelt, Leipzig (Germany). Bereich Simulatorenentwicklung


    The following article describes a PC program package for the training of load switching in electrical power supply and distribution station under normal, critical and fault conditions. It contains load flow and short circuit calculation, station interlocking checking and protection device simulation. There exist a single user version as well as a multi user version intended for group switching training. (orig.) [Deutsch] Die Verfasser stellen ein PC-Programmsystem zum Training von Schalthandlungen in elektrischen Energieversorgungsanlagen unter Normal- und Ausnahmebedingungen vor. Es enhaelt Lastfluss- und Kurzschlussberechnung, Verriegelungsueberpruefung und Schutzemulation. Es ist sowohl eine Einzelplatz- als auch eine Mehrplatzversion zum Gruppenschalttraining verfuegbar. (orig.)

  1. Simulation of Structures Exhibiting Instability Under Thermal-Mechanical Transient Loading (United States)


    arches represented in the space of ),( lmiduD : (a) No imperfection, (b) 001.0and,005.0,03.0 642 === eee . BY14-020SP: Simulation of Structures...sine arches represented in the space of ),( lp : (a) No imperfection, (b) 001.0and,005.0,03.0 642 === eee . Critical Loads In this part, the

  2. FEM simulation of static loading test of the Omega beam (United States)

    Bílý, Petr; Kohoutková, Alena; Jedlinský, Petr


    The paper deals with a FEM simulation of static loading test of the Omega beam. Omega beam is a precast prestressed high-performance concrete element with the shape of Greek letter omega. Omega beam was designed as a self-supporting permanent formwork member for construction of girder bridges. FEM program ATENA Science was exploited for simulation of load-bearing test of the beam. The numerical model was calibrated using the data from both static loading test and tests of material properties. Comparison of load-displacement diagrams obtained from the experiment and the model was conducted. Development of cracks and crack patterns were compared. Very good agreement of experimental data and the FEM model was reached. The calibrated model can be used for design of optimized Omega beams in the future without the need of expensive loading tests. The calibrated material model can be also exploited in other types of FEM analyses of bridges constructed with the use of Omega beams, such as limit state analysis, optimization of shear connectors, prediction of long-term deflections or prediction of crack development.

  3. Electromagnetic simulations of simple models of ferrite loaded kickers

    CERN Document Server

    Zannini, Carlo; Salvant, B; Metral, E; Rumolo, G


    The kickers are major contributors to the CERN SPS beam coupling impedance. As such, they may represent a limitation to increasing the SPS bunch current in the frame of an intensity upgrade of the LHC. In this paper, CST Particle Studio time domain electromagnetic simulations are performed to obtain the longitudinal and transverse impedances/wake potentials of simplified models of ferrite loaded kickers. The simulation results have been successfully compared with some existing analytical expressions. In the transverse plane, the dipolar and quadrupolar contributions to the wake potentials have been estimated from the results of these simulations. For some cases, simulations have also been benchmarked against measurements on PS kickers. It turns out that the large simulated quadrupolar contributions of these kickers could explain both the negative total (dipolar+quadrupolar) horizontal impedance observed in bench measurements and the positive horizontal tune shift measured with the SPS beam.

  4. Systems modeling and simulation applications for critical care medicine (United States)


    Critical care delivery is a complex, expensive, error prone, medical specialty and remains the focal point of major improvement efforts in healthcare delivery. Various modeling and simulation techniques offer unique opportunities to better understand the interactions between clinical physiology and care delivery. The novel insights gained from the systems perspective can then be used to develop and test new treatment strategies and make critical care delivery more efficient and effective. However, modeling and simulation applications in critical care remain underutilized. This article provides an overview of major computer-based simulation techniques as applied to critical care medicine. We provide three application examples of different simulation techniques, including a) pathophysiological model of acute lung injury, b) process modeling of critical care delivery, and c) an agent-based model to study interaction between pathophysiology and healthcare delivery. Finally, we identify certain challenges to, and opportunities for, future research in the area. PMID:22703718

  5. Simulation platform developed to study and identify critical cases in a future smart grid

    DEFF Research Database (Denmark)

    Mihet-Popa, Lucian; Zong, Yi; You, Shi


    simulation and planning tools, with a particular objective on the challenges faced by the introduction of Smart Grid technologies. Another important issue of the paper is to identify critical load cases, as well as the voltage variations with the highest potential, able to implement the grid model......This paper proposes a simulation platform developed to study and identify critical cases in a Smart Grid. A distribution network with different Distributed Energy Resources (DER) components, connected along the feeders, is analyzed, having the objective to identify limitations of existing...

  6. Development and Implementation of Critical Loads for Atmospheric Deposition: Federal Land Management Implications (United States)

    Porter, E. M.


    Critical loads for atmospheric deposition have been widely developed and used in Europe, Canada, and other countries. Critical loads are used to influence air pollution emissions reductions, thereby protecting and restoring aquatic and terrestrial ecosystems. In the United States, federal land management agencies are adopting the critical load concept as a potentially valuable resource management tool. Certain parks and wilderness areas are currently being affected by anthropogenic nitrogen and sulfur deposition. Effects of excess deposition include acidification, nitrogen enrichment, toxicity, and changes in biotic communities. Streams in both Shenandoah and Great Smoky Mountains National Parks are experiencing chronic and episodic acidification and brook trout fisheries in Shenandoah have been affected. High elevation ecosystems in Rocky Mountain National Park are undergoing subtle changes in aquatic and terrestrial ecosystems attributable to atmospheric deposition. Natural resources in many other federal areas have been affected or are at risk from deposition. Federal land managers are refining strategies for critical loads that include working with scientists to identify resources sensitive to deposition, defining resource protection criteria that will meet management objectives, and estimating and implementing critical loads. Critical loads will be used in resource management decisions and federal land management planning. They will be used to evaluate management actions and assess progress towards meeting management goals. Federal land managers will also communicate critical loads information to air pollution regulatory agencies to inform emissions management strategies for clean air.

  7. Plant species diversity indicators for use in the computation of critical loads and dynamic risk assessments

    NARCIS (Netherlands)

    Dobben, van H.F.; Posch, M.; Wamelink, G.W.W.; Hettelingh, J.P.; Vries, de W.


    Soil models can be used to derive critical loads by computing the deposition that leads to critical limits for abiotic conditions, i.e. conditions that are just tolerated by an ecosystem. In this chapter various approaches are discussed to assess these critical limits for plant communities and plant

  8. On the way to reliable aeroelastic load simulation on VAWT's

    DEFF Research Database (Denmark)

    Larsen, Torben J.; Aagaard Madsen, Helge


    for a full load analysis relating to eg. certification of a VAWT turbine. Further on, principal load cases according to the IEC61400-1 are simulated for a fictitious 5MW VAWT turbine in it’s simplest 2 bladed Darrieus configuration. The IEC61400-1 load cases, originally developed for Horizontal Axis Wind......In this paper a method for an implementation of a 2D actuator cylinder flow model of an Vertical Axis Wind Turbine (VAWT) is presented. The model is implemented in a full aeroelastic code including consideration of structural dynamics, dynamic inflow, tower shadow and dynamic stall, which is needed...... Turbines (HAWT’s), are discussed regarding the application to VAWT’s. Further on a small section regarding aerodynamic flow in curved motion is included....

  9. On the way to reliable aeroelastic load simulation on VAWT's

    DEFF Research Database (Denmark)

    Larsen, Torben J.; Aagaard Madsen, Helge

    for a full load analysis relating to eg. certification of a VAWT turbine. Further on, principal load cases according to the IEC61400-1 are simulated for a fictitious 5MW VAWT turbine in it’s simplest 2 bladed Darrieus configuration. The IEC61400-1 load cases, originally developed for Horizontal Axis Wind......In this paper a method for an implementation of a 2D actuator cylinder flow model of an Vertical Axis Wind Turbine (VAWT) is presented. The model is implemented in a full aeroelastic code including consideration of structural dynamics, dynamic inflow, tower shadow and dynamic stall, which is needed...... Turbines (HAWT’s), are discussed regarding the application to VAWT’s. Further on a small section regarding aerodynamic flow in curved motion is included....

  10. Simulations of Alpha Wall Load in ITER. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Carlsson, Johan


    The partially DOE funded International Thermonuclear Experimental Reactor (ITER) will produce massive amounts of energetic charged alpha particles, which are imperfectly confined by a strong magnetic field. The wall of the experiment is designed to withstand an estimated wall load from these fusion alpha particles, but the accuracy of this estimate needs to be improved to avoid potentially catastrophic surprises when the experiment becomes operational. We have added a more accurate, gyro-dynamic model of particle motion to the existing drift-dynamic model in the DELTA5D simulation software used for the project. We have also added the ability to load a detailed engineering model of the wall and use it in the simulations.

  11. Mobile Learning Games for Critical Decision Making and Crisis Simulation


    Kalz, Marco


    This presentation provides an overview about different approaches of the mobile learning group of the Welten Institute regarding the design and evaluation of mobile learning games for critical decision making and crisis simulation.

  12. Modeling and mapping of critical loads for heavy metals in Kunshan soil. (United States)

    Wu, Shaohua; Shi, Yaxing; Zhou, Shenglu; Wang, Chunhui; Chen, Hao


    The assessment of critical loads of metals in soil can be used as an important tool for evaluation and for risk precaution of future inputs of metal in order to avoid the occurrence of heavy metal pollution and its long-term risks for people. In this study, critical loads of Cd, Cu, and Pb in farming and non-farming areas of Kunshan were calculated based on three main effects. Two of these effects, limit value of daily metals dose and different environmental water quality criteria are new ways to calculate the critical content of heavy metals. The mean value of critical loads decreased in the order Cu>Pb>Cd when calculated using mass balance effects, child health risk effects, and adult health risk effects. Critical loads were highest in the areas near construction land, areas of low critical load were scattered throughout the city. The areal proportion of critical load exceedance is greatest for Pb based on mass balance effects, followed by Cu based on water quality effects, and Cd based on mass balance effects. Exceedances only occurred in 6% and 3% of farming areas for water quality effects for Cd and Pb when compared critical load values to the input fluxes in the Yangtze River delta. However, for these metals, values were up to 83% and 100%, respectively, based on mass balance effects. Exceedances completely covered non-farming areas for each effect for Pb. Most exceedances occurred in the north and south of the city in non-farming areas. Spatially explicit critical loads of heavy metals based on the different effects can serve as a reference for controlling the emissions of heavy metals effectively and meeting the demands of different management objectives. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Federated Modelling and Simulation for Critical Infrastructure Protection

    NARCIS (Netherlands)

    Rome, E.; Langeslag, P.J.H.; Usov, A.


    Modelling and simulation is an important tool for Critical Infrastructure (CI) dependency analysis, for testing methods for risk reduction, and as well for the evaluation of past failures. Moreover, interaction of such simulations with external threat models, e.g., a river flood model, or economic

  14. Nitrogen critical loads and management alternatives for N-impacted ecosystems in California (United States)

    M.E. Fenn; E.B. Allen; S.B. Weiss; S. Jovan; L. Geiser; G.S. Tonnesen; R.F. Johnson; L.E. Rao; B.S. Gimeno; F. Yuan; T. Meixner; A. Bytnerowicz


    Empirical critical loads for N deposition effects and maps showing areas projected to be in exceedance of the critical load (CL) are given for seven major vegetation types in California. Thirty-five percent of the land area for these vegetation types (99,639 km2) is estimated to be in excess of the N CL. Low CL values (3–8...

  15. Mapping critical levels/loads for the Slovak Republic. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Zavodsky, D.; Babiakova, G.; Mitosinkova, M. [and others


    As a part of the Agreement on Environmental Cooperation between Norway and Slovakia a project ``Mapping Critical Levels/Loads for Slovakia`` was established. This report presents the final project results. Critical loads for forest, surface and ground waters and their exceedances were calculated by means of the steady-state mass balance model PROFILE for soils, and the steady-state water chemistry method for waters. A grid distance of 10 km was used. Because the sulphur deposition has been decreasing, the exceedances of critical load of acidity and critical sulphur deposition of forest soils have decreased from 1990 to 1995. Practically no acidity exceedances for surface water or ground water were found in 1995. The critical level of forest ozone was exceeded all over Slovakia. In the Tatra mountains the exceedance was over 25000 ppb.h. 23 refs., 3 figs., 3 tabs.

  16. Computer modeling of road bridge for simulation moving load

    Directory of Open Access Journals (Sweden)

    Miličić Ilija M.


    Full Text Available In this paper is shown computational modelling one span road structures truss bridge with the roadway on the upper belt of. Calculation models were treated as planar and spatial girders made up of 1D finite elements with applications for CAA: Tower and Bridge Designer 2016 (2nd Edition. The conducted computer simulations results are obtained for each comparison of the impact of moving load according to the recommendations of the two standards SRPS and AASHATO. Therefore, it is a variant of the bridge structure modeling application that provides Bridge Designer 2016 (2nd Edition identical modeled in an environment of Tower. As important information for the selection of a computer applications point out that the application Bridge Designer 2016 (2nd Edition we arent unable to treat the impacts moving load model under national standard - V600. .

  17. An Efficient Simulated Annealing Algorithm for Economic Load Dispatch Problems

    Directory of Open Access Journals (Sweden)

    Junaidi Junaidi


    Full Text Available This paper presents an efficient simulated annealing (SA algorithm for solving economic load dispatch (ELD problems in electrical power system. The objectives of ELD problems in electric power generation is to programmed the devoted generating unit outputs so as to meet the mandatory load demand at lowest amount operating cost while satisfying all units and system equality and inequality constraints. Global optimization approaches is inspired by annealing process of thermodynamics. The SA algorithm presented here is applied to two case studies, which analyze power systems having three, and six generating units. The results determined by SA algorithm are compared to those found by conventional quadratic programming (QP and genetic algorithm (GA.

  18. Microgrids for Service Restoration to Critical Load in a Resilient Distribution System

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yin; Liu, Chen-Ching; Schneider, Kevin P.; Tuffner, Francis K.; Ton, Dan T.


    icrogrids can act as emergency sources to serve critical loads when utility power is unavailable. This paper proposes a resiliency-based methodology that uses microgrids to restore critical loads on distribution feeders after a major disaster. Due to limited capacity of distributed generators (DGs) within microgrids, dynamic performance of the DGs during the restoration process becomes essential. In this paper, the stability of microgrids, limits on frequency deviation, and limits on transient voltage and current of DGs are incorporated as constraints of the critical load restoration problem. The limits on the amount of generation resources within microgrids are also considered. By introducing the concepts of restoration tree and load group, restoration of critical loads is transformed into a maximum coverage problem, which is a linear integer program (LIP). The restoration paths and actions are determined for critical loads by solving the LIP. A 4-feeder, 1069-bus unbalanced test system with four microgrids is utilized to demonstrate the effectiveness of the proposed method. The method is applied to the distribution system in Pullman, WA, resulting in a strategy that uses generators on the Washington State University campus to restore service to the Hospital and City Hall in Pullman.

  19. Water pollution abatement programme. The Czech Republic. Project 4.2. Assessing critical loads of acidity to surface waters in The Czech Republic. Critical loads of acidity to surface waters, Northern Moravia and Silesia, The Czech Republic

    Energy Technology Data Exchange (ETDEWEB)

    Lien, L.; Raclavsky, K.; Henriksen, A.; Raclavska, H.; Matysek, D.


    The governments of Norway and Czech and Slovak Federal Republic have signed a bilateral environmental protection agreement. This report describes Project 4.2 of the agreement: Assessing critical loads of acidity to surface waters in The Czech Republic. Critical load of acidity to surface waters and exceedance of critical load were estimated by using standard methods modified for the sampling area. Water samples were mainly taken from small forest streams, which were the only available surface waters with negligible pollution from local sources. High critical loads were calculated, averaging 20 times higher than the corresponding value for southern Norway. The deposition of acidifying components in the region was high, but did not exceed the critical load and so there is a reserve for additional acid deposition. Scattered water analyses from several other parts of The Czech Republic indicate both low critical loads and exceedance of critical load in various regions (e.g. Bohemia). 21 refs., 14 figs., 3 tabs.

  20. Steady-state critical loads of acidity for forest soils in the Georgia Basin, British Columbia

    Directory of Open Access Journals (Sweden)

    Shaun A. WATMOUGH


    Full Text Available There has been growing interest in acid rain research in western Canada where sulphur (S and nitrogen (N emissions are expected to increase during the next two decades. One region of concern is southern British Columbia, specifically the Georgia Basin, where emissions are expected to increase owing to the expansion of industry and urban centres (Vancouver and Victoria. In the current study, weathering rates and critical loads of acidity (S and N for forest soils were estimated at nineteen sites located within the Georgia Basin. A base cation to aluminium ratio of 10 was selected as the critical chemical criterion associated with ecosystem damage. The majority of the sites (58% had low base cation weathering rates (≤50 meq m–2 y–1 based on the PROFILE model. Accordingly, mean critical load for the study sites, estimated using the steady-state mass balance model, ranged between 129–168 meq m–2 y–1. Annual average total (wet and dry S and N deposition during the period 2005–2006 (estimated by the Community Multiscale Air Quality model, exceeded critical load at five–nine of the study sites (mean exceedance = 32–46 meq m–2 y–1. The high-elevation (>1000 m study sites had shallow, acid sensitive, soils with low weathering rates; however, critical loads were predominantly exceeded at sites close to Vancouver under higher modelled deposition loads. The extent of exceedance is similar to other industrial regions in western and eastern Canada.

  1. FLUKA Simulations for SEE Studies of Critical LHC Underground Areas

    CERN Document Server

    Roed, K; Brugger, M; Spiezia, G; Losito, R; Boccone, V; Ferrari, A; Versaci, R; Lebbos, E; Mereghetti, A


    FLUKA Monte Carlo simulations have been performed to identify particle energy spectra and fluences relevant for evaluating the risk of single event effects in electronics installed in critical LHC underground areas. Since these simulations are associated with significant uncertainties, the results will compared with an online monitoring system installed to evaluate radiation levels at the location of the electronics. This comparison approach have been benchmarked in a mixed field reference facility and for a preliminary LHC monitoring case study.

  2. Estimation of fatigue strength under multiaxial cyclic loading by varying the critical plane orientation

    Directory of Open Access Journals (Sweden)

    Marta Kurek


    Full Text Available The main purpose of this paper is to examine the influence of the critical plane orientation on the estimated fatigue strength of metals under multiaxial loading. The algorithm employed to evaluate fatigue strength implements the criterion of maximum normal and shear stress on a suitable damage plane (critical plane. The angle  defining the critical plane orientation is measured with respect to the direction that maximises the applied normal stress. Eleven (11 structural materials under combined bending and torsion cyclic loading are examined. For each analysed material, the value of  angle is selected so that the value of the scatter, defined by a root-mean-square value, is minimum. On the basis of such a calculation, an empirical expression for  is proposed, that takes into account the values of bending and torsion fatigue strengths at a reference number of loading cycles. According to such an expression,  is constant for a given material.

  3. Utilizing an Energy Management System with Distributed Resources to Manage Critical Loads and Reduce Energy Costs (United States)


    embedded in a PV inverter, from [8]. ....................................7  Figure 2.  Simplified operating point for load and PV array , from [13...periods and discharge it during peak periods. They can also be utilized in conjunction with PV arrays to provide islanding capability if the critical loads ...such as photovoltaic ( PV ) arrays and wind turbines. The microgrid could either include the entire installation or portions of the installation. The

  4. Action Simulation Plays a Critical Role in Deceptive Action Recognition

    NARCIS (Netherlands)

    Tidoni, Emmanuele; Borgomaneri, Sara; Di Pellegrino, Giuseppe; Avenanti, Alessio


    The ability to infer deceptive intents from nonverbal behavior is critical for social interactions. By combining single-pulse and repetitive transcranial magnetic stimulation (TMS) in healthy humans, we provide both correlational and causative evidence that action simulation is actively involved in

  5. Critical slowing down and error analysis in lattice QCD simulations

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, Stefan [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Sommer, Rainer; Virotta, Francesco [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC


    We study the critical slowing down towards the continuum limit of lattice QCD simulations with Hybrid Monte Carlo type algorithms. In particular for the squared topological charge we find it to be very severe with an effective dynamical critical exponent of about 5 in pure gauge theory. We also consider Wilson loops which we can demonstrate to decouple from the modes which slow down the topological charge. Quenched observables are studied and a comparison to simulations of full QCD is made. In order to deal with the slow modes in the simulation, we propose a method to incorporate the information from slow observables into the error analysis of physical observables and arrive at safer error estimates. (orig.)

  6. Derivation and Mapping of Critical Loads for Nitrogen and Trends in Their Exceedance in Germany

    Directory of Open Access Journals (Sweden)

    Hans-Dieter Nagel


    Full Text Available The term “critical load” means a quantitative estimate of an exposure to one or more pollutants below which significant harmful effects on specified sensitive elements of the environment do not occur, according to present knowledge. In the case of nitrogen, both oxidised and reduced compounds contribute to the total deposition of acidity, which exceeds critical loads in many forest ecosystems. These also cause negative effects through eutrophication. Critical loads of nitrogen were derived for forest soils (deciduous and coniferous forest, natural grassland, acid fens, heathland, and mesotrophic peat bogs. In Germany, a decrease in sulphur emissions over the past 15 years resulted in a reduced exceedance of critical loads for acid deposition. In the same period it was noted that reduction in the emissions of nitrogen oxides and ammonia remained insignificant. Therefore, emissions of nitrogen compounds have become relatively more important and will continue to threaten ecosystem function and stability. The risk of environmental damage remains at an unacceptable level. The German maps show the degree to which the critical loads are exceeded, and they present current developments and an expected future trend. Results indicate that recovery from pollutant stress occurs only gradually.

  7. Autonomous Cryogenics Loading Operations Simulation Software: Knowledgebase Autonomous Test Engineer (United States)

    Wehner, Walter S., Jr.


    Working on the ACLO (Autonomous Cryogenics Loading Operations) project I have had the opportunity to add functionality to the physics simulation software known as KATE (Knowledgebase Autonomous Test Engineer), create a new application allowing WYSIWYG (what-you-see-is-what-you-get) creation of KATE schematic files and begin a preliminary design and implementation of a new subsystem that will provide vision services on the IHM (Integrated Health Management) bus. The functionality I added to KATE over the past few months includes a dynamic visual representation of the fluid height in a pipe based on number of gallons of fluid in the pipe and implementing the IHM bus connection within KATE. I also fixed a broken feature in the system called the Browser Display, implemented many bug fixes and made changes to the GUI (Graphical User Interface).

  8. Water pollution abatement programme. The Czech Republic. Project 4.2. Assessing critical loads of acidity to surface waters in the Czech Republic. Critical loads of acidity to surface waters, north-eastern Bohemia and northern Moravia, The Czech Republic

    Energy Technology Data Exchange (ETDEWEB)

    Lien, L.; Raclavsky, K.; Raclavska, H.; Matysek, D.; Hovind, H.


    This report discusses estimates of critical loads of acidity to surface waters and their exceedances, for north-eastern Bohemia and Moravia in The Czech Republic. The survey covers 13 400 km{sup 2}, or 17% of the area of the country. Varying critical loads were observed within the examined region. 19% of the examined area showed exceedance of critical load and another 11% was close to exceedance. The survey should continue in Bohemia. 24 refs., 20 figs., 4 tabs.

  9. Comparison between simplified load spectra in accordance with Germanische Lloyd guidelines, and load spectra derived from time domain simulations

    Energy Technology Data Exchange (ETDEWEB)

    Rees, M. [Aerodyn Energiesysteme gmbH, Rendsburg (Germany)


    The Germanische Lloyd guideline allows calculations of load spectra in two fundamentally different ways. In the case of the so-called `simplified load spectra` the maximum amplitude of fluctuation of a load component is formed as {+-}75% of the average value of the purely aerodynamic loads of this component at rated wind conditions, together with an overlay of mass-related loads. The second method allowed in the GL guideline is the calculation of load spectra from simulation results in the time domain. For a number of average wind speeds the time-dependent characteristics of the load components are calculated taking account of the natural spatial turbulence of the wind. These are converted into load spectra using the rainflow method. In a parametric study the load spectra are calculated according to both methods and compared. The calculations are performed for turbines with rated powers of 100 kW to 2000 kW, with two and three blades, and also for stall-controlled and pitch-controlled turbines. The calculated load spectra are compared with each by means of 1 P fatigue equivalent load spectra. The influence of individual parameters is presented, as is the validity of the simplified load spectra. (au)

  10. Simulated and Virtual Science Laboratory Experiments: Improving Critical Thinking and Higher-Order Learning Skills (United States)

    Simon, Nicole A.

    Virtual laboratory experiments using interactive computer simulations are not being employed as viable alternatives to laboratory science curriculum at extensive enough rates within higher education. Rote traditional lab experiments are currently the norm and are not addressing inquiry, Critical Thinking, and cognition throughout the laboratory experience, linking with educational technologies (Pyatt & Sims, 2007; 2011; Trundle & Bell, 2010). A causal-comparative quantitative study was conducted with 150 learners enrolled at a two-year community college, to determine the effects of simulation laboratory experiments on Higher-Order Learning, Critical Thinking Skills, and Cognitive Load. The treatment population used simulated experiments, while the non-treatment sections performed traditional expository experiments. A comparison was made using the Revised Two-Factor Study Process survey, Motivated Strategies for Learning Questionnaire, and the Scientific Attitude Inventory survey, using a Repeated Measures ANOVA test for treatment or non-treatment. A main effect of simulated laboratory experiments was found for both Higher-Order Learning, [F (1, 148) = 30.32,p = 0.00, eta2 = 0.12] and Critical Thinking Skills, [F (1, 148) = 14.64,p = 0.00, eta 2 = 0.17] such that simulations showed greater increases than traditional experiments. Post-lab treatment group self-reports indicated increased marginal means (+4.86) in Higher-Order Learning and Critical Thinking Skills, compared to the non-treatment group (+4.71). Simulations also improved the scientific skills and mastery of basic scientific subject matter. It is recommended that additional research recognize that learners' Critical Thinking Skills change due to different instructional methodologies that occur throughout a semester.

  11. a model for the determination of the critical buckling load of self ...

    African Journals Online (AJOL)


    Most tall columns under axial load fail by buckling. Considering the widespread use of this type of structure and the critical role it plays in service delivery, its failure will result in possible loss of lives and property and disruption of services. It is therefore necessary to evolve alternative methods of determination of the buckling ...

  12. Effect of ventilation rate and board loading on formaldehyde concentration : a critical review of the literature (United States)

    George E. Myers


    A critical literature review has been carried out on the influence of ventilation rate (N, hr.-1) and board loading (L, m2/m3) on steady state formaldehyde concentrations (Cs, ppm) resulting from particleboard and plywood emissions. Large differences exist among boards in the extent to which their formaldehyde concentrations change with N or L in laboratory chambers....

  13. Uncertainty analysis on simple mass balance model to calculate critical loads for soil acidity (United States)

    Harbin Li; Steven G. McNulty


    Simple mass balance equations (SMBE) of critical acid loads (CAL) in forest soil were developed to assess potential risks of air pollutants to ecosystems. However, to apply SMBE reliably at large scales, SMBE must be tested for adequacy and uncertainty. Our goal was to provide a detailed analysis of uncertainty in SMBE so that sound strategies for scaling up CAL...

  14. Airborne pollutants. Transports, effects and critical loads; Lufttransporterte forurensninger. Tilfoersler, virkninger og taalegrenser

    Energy Technology Data Exchange (ETDEWEB)

    Floeysand, I.; Loebersli, E. [eds.


    The report from a conference concerns two Norwegian research programmes. The first one deals with the transports and effects of airborne pollutants, and the second one relates to the critical loads of nature. A number of 17 papers from the conference are prepared. 318 refs., 57 figs., 22 tabs.

  15. a model for the determination of the critical buckling load of self ...

    African Journals Online (AJOL)


    supporting lattice towers. This paper therefore proposes a simple model for the determination of the critical buckling load of self- supporting lattice towers. The proposed model idealizes the lattice tower as an equivalent solid beam- column whose cross-sectional-dimensions are the unknowns to be determined.

  16. A comparison of empirical and modeled nitrogen critical loads for Mediterranean forests and shrublands in California (United States)

    M.E. Fenn; H.-D. Nagel; I. Koseva; J. Aherne; S.E. Jovan; L.H. Geiser; A. Schlutow; T. Scheuschner; A. Bytnerowicz; B.S. Gimeno; F. Yuan; S.A. Watmough; E.B. Allen; R.F. Johnson; T. Meixner


    Nitrogen (N) deposition is impacting a number of ecosystem types in California. Critical loads (CLs) for N deposition determined for mixed conifer forests and chaparral/oak woodlands in the Sierra Nevada Mountains of California and the San Bernardino Mountains in southern California using empirical and various modelling approaches were compared. Models used included...

  17. Lichen-based critical loads for atmospheric nitrogen deposition in Western Oregon and Washington forests, USA (United States)

    Linda H. Geiser; Sarah E. Jovan; Doug A. Glavich; Matthew K. Porter


    Critical loads (CLs) define maximum atmospheric deposition levels apparently preventative of ecosystem harm. We present first nitrogen CLs for northwestern North America's maritime forests. Using multiple linear regression, we related epiphytic-macrolichen community composition to: 1) wet deposition from the National Atmospheric Deposition Program, 2) wet, dry,...

  18. The history and current state of critical loads and dynamic modelling assessments

    NARCIS (Netherlands)

    Vries, de W.; Hettelingh, J.P.; Posch, M.


    This book focuses on knowledge and methods for the assessment of indirect, soil mediated effects of the deposition of sulphur dioxide, oxidized nitrogen and reduced nitrogen on terrestrial and aquatic ecosystems. The emphasis is on the science behind no-effect deposition thresholds (critical loads)

  19. Critical acid load limits in a changing climate: implications and solutions (United States)

    Steven G. McNulty


    The federal agencies of the United States are currently developing guidelines for critical nitrogen load limits for U.S. forest ecosystems. These guidelines will be used to develop regulations designed to maintain pollutant inputs below the level shown to damage specified ecosystems.

  20. Site-specific critical acid load estimates for forest soils in the Osborn Creek watershed, Michigan (United States)

    Trevor Hobbs; Jason Lynch; Randy. Kolka


    Anthropogenic acid deposition has the potential to accelerate leaching of soil cations, and in turn, deplete nutrients essential to forest vegetation. The critical load concept, employing a simple mass balance (SMB) approach, is often used to model this process. In an evaluation under the U.S. Forest Service Watershed Condition Framework program, soils in all 6th level...

  1. Effects of nitrogen deposition and empirical nitrogen critical loads for ecoregions of the United States (United States)

    Pardo, L.H.; Fenn, M.E.; Goodale, C.L.; Geiser, L.H.; Driscoll, C.T.; Allen, E.B.; Baron, Jill S.; Bobbink, R.; Bowman, W.D.; Clark, C.M.; Emmett, B.; Gilliam, F.S.; Greaver, T.L.; Hall, S.J.; Lilleskov, E.A.; Liu, L.; Lynch, J.A.; Nadelhoffer, K.J.; Perakis, S.S.; Robin-Abbott, M. J.; Stoddard, J.L.; Weathers, K.C.; Dennis, R.L.


    Human activity in the last century has led to a significant increase in nitrogen (N) emissions and atmospheric deposition. This N deposition has reached a level that has caused or is likely to cause alterations to the structure and function of many ecosystems across the United States. One approach for quantifying the deposition of pollution that would be harmful to ecosystems is the determination of critical loads. A critical load is defined as the input of a pollutant below which no detrimental ecological effects occur over the long-term according to present knowledge. The objectives of this project were to synthesize current research relating atmospheric N deposition to effects on terrestrial and freshwater ecosystems in the United States, and to estimate associated empirical N critical loads. The receptors considered included freshwater diatoms, mycorrhizal fungi, lichens, bryophytes, herbaceous plants, shrubs, and trees. Ecosystem impacts included: (1) biogeochemical responses and (2) individual species, population, and community responses. Biogeochemical responses included increased N mineralization and nitrification (and N availability for plant and microbial uptake), increased gaseous N losses (ammonia volatilization, nitric and nitrous oxide from nitrification and denitrification), and increased N leaching. Individual species, population, and community responses included increased tissue N, physiological and nutrient imbalances, increased growth, altered root : shoot ratios, increased susceptibility to secondary stresses, altered fire regime, shifts in competitive interactions and community composition, changes in species richness and other measures of biodiversity, and increases in invasive species. The range of critical loads for nutrient N reported for U.S. ecoregions, inland surface waters, and freshwater wetlands is 1-39 kg N.ha -1.yr -1, spanning the range of N deposition observed over most of the country. The empirical critical loads for N tend to

  2. Criticality Safety Analysis Of As-loaded Spent Nuclear Fuel Casks

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Kaushik [ORNL; Scaglione, John M [ORNL


    The final safety analysis report (FSAR) or the safety analysis report (SAR) for a particular spent nuclear fuel (SNF) cask system documents models and calculations used to demonstrate that a system meets the regulatory requirements under all normal, off-normal, and accident conditions of spent fuel storage, and normal and accident conditions of transportation. FSAR/SAR calculations and approved content specifications are intended to be bounding in nature to certify cask systems for a variety of fuel characteristics with simplified SNF loading requirements. Therefore, in general, loaded cask systems possess excess and uncredited criticality margins (i.e., the difference between the licensing basis and the as-loaded calculations). This uncredited margin could be quantified by employing more detailed cask-specific evaluations that credit the actual as-loaded cask inventory, and taking into account full (actinide and fission product) burnup credit. This uncredited criticality margin could be potentially used to offset (1) uncertainties in the safety basis that needs to account for the effects of system aging during extended dry storage prior to transportation, and (2) increases in SNF system reactivity over a repository performance period (e.g., 10,000 years or more) as the system undergoes degradation and internal geometry changes. This paper summarizes an assessment of cask-specific, as-loaded criticality margins for SNF stored at eight reactor sites (215 loaded casks were analyzed) under fully flooded conditions to assess the margins available during transportation after extended storage. It is observed that the calculated keff margin varies from 0.05 to almost 0.3 Δkeff for the eight selected reactor sites, demonstrating that significant uncredited safety margins are present. In addition, this paper evaluates the sufficiency of this excess margin in applications involving direct disposal of currently loaded SNF casks.

  3. Power Generation by Zinc Antimonide Thin Film under Various Load Resistances at its Critical Operating Temperature

    DEFF Research Database (Denmark)

    Mir Hosseini, Seyed Mojtaba; Rezaniakolaei, Alireza; Rosendahl, Lasse Aistrup

    thin films operating under different load resistances at around its critical operating temperature, 400 ᵒC. The thermoelement is subjected to constant hot side temperature and to room temperature at the cold junction in order to measure the thin film TEG’s sample performance. The nominal loads equal...... to 10, 15, 20, 25, 30, 35, 40, 45… 175, and also 200 Ohms were applied. The results show that the value of the Seebeck coefficient is 0.0002 [V/K] for the specimen, which is in agreement with quantities of other zinc antimonide bulks materials in literature. The results also show that the voltage...... slightly reduces during unload conditions, although it is expected that by eliminating load in each step, the initial amount of voltage exactly repeats. Similar behavior is observed for Seebeck coefficient distribution versus time of working particularly in lower load resistances. Based on variation...

  4. Phase-field model simulation of ferroelectric/antiferroelectric materials microstructure evolution under multiphysics loading (United States)

    Zhang, Jingyi

    Ferroelectric (FE) and closely related antiferroelectric (AFE) materials have unique electromechanical properties that promote various applications in the area of capacitors, sensors, generators (FE) and high density energy storage (AFE). These smart materials with extensive applications have drawn wide interest in the industrial and scientific world because of their reliability and tunable property. However, reliability issues changes its paradigms and requires guidance from detailed mechanism theory as the materials applications are pushed for better performance. A host of modeling work were dedicated to study the macro-structural behavior and microstructural evolution in FE and AFE material under various conditions. This thesis is focused on direct observation of domain evolution under multiphysics loading for both FE and AFE material. Landau-Devonshire time-dependent phase field models were built for both materials, and were simulated in finite element software Comsol. In FE model, dagger-shape 90 degree switched domain was observed at preexisting crack tip under pure mechanical loading. Polycrystal structure was tested under same condition, and blocking effect of the growth of dagger-shape switched domain from grain orientation difference and/or grain boundary was directly observed. AFE ceramic model was developed using two sublattice theory, this model was used to investigate the mechanism of energy efficiency increase with self-confined loading in experimental tests. Consistent results was found in simulation and careful investigation of calculation results gave confirmation that origin of energy density increase is from three aspects: self-confinement induced inner compression field as the cause of increase of critical field, fringe leak as the source of elevated saturation polarization and uneven defects distribution as the reason for critical field shifting and phase transition speed. Another important affecting aspect in polycrystalline materials is the

  5. Limitations of subjective cognitive load measures in simulation-based procedural training. (United States)

    Naismith, Laura M; Cheung, Jeffrey J H; Ringsted, Charlotte; Cavalcanti, Rodrigo B


    The effective implementation of cognitive load theory (CLT) to optimise the instructional design of simulation-based training requires sensitive and reliable measures of cognitive load. This mixed-methods study assessed relationships between commonly used measures of total cognitive load and the extent to which these measures reflected participants' experiences of cognitive load in simulation-based procedural skills training. Two groups of medical residents (n = 38) completed three questionnaires after participating in simulation-based procedural skills training sessions: the Paas Cognitive Load Scale; the NASA Task Load Index (TLX), and a cognitive load component (CLC) questionnaire we developed to assess total cognitive load as the sum of intrinsic load (how complex the task is), extraneous load (how the task is presented) and germane load (how the learner processes the task for learning). We calculated Pearson's correlation coefficients to assess agreement among these instruments. Group interviews explored residents' perceptions about how the simulation sessions contributed to their total cognitive load. Interviews were audio-recorded, transcribed and subjected to qualitative content analysis. Total cognitive load scores differed significantly according to the instrument used to assess them. In particular, there was poor agreement between the Paas Scale and the TLX. Quantitative and qualitative findings supported intrinsic cognitive load as synonymous with mental effort (Paas Scale), mental demand (TLX) and task difficulty and complexity (CLC questionnaire). Additional qualitative themes relating to extraneous and germane cognitive loads were not reflected in any of the questionnaires. The Paas Scale, TLX and CLC questionnaire appear to be interchangeable as measures of intrinsic cognitive load, but not of total cognitive load. A more complete understanding of the sources of extraneous and germane cognitive loads in simulation-based training contexts is

  6. A conceptual framework: Redefining forest soil's critical acid loads under a changing climate

    Energy Technology Data Exchange (ETDEWEB)

    McNulty, Steven G., E-mail: steve_mcnulty@ncsu.ed [USDA Forest Service, Eastern Forests Environmental Assessment Threats Center, Southern Global Change Program, 920 Main Campus Dr. Suite 300, Raleigh, NC 27606 (United States); Boggs, Johnny L. [USDA Forest Service, Eastern Forests Environmental Assessment Threats Center, Southern Global Change Program, 920 Main Campus Dr. Suite 300, Raleigh, NC 27606 (United States)


    Federal agencies of several nations have or are currently developing guidelines for critical forest soil acid loads. These guidelines are used to establish regulations designed to maintain atmospheric acid inputs below levels shown to damage forests and streams. Traditionally, when the critical soil acid load exceeds the amount of acid that the ecosystem can absorb, it is believed to potentially impair forest health. The excess over the critical soil acid load is termed the exceedance, and the larger the exceedance, the greater the risk of ecosystem damage. This definition of critical soil acid load applies to exposure of the soil to a single, long-term pollutant (i.e., acidic deposition). However, ecosystems can be simultaneously under multiple ecosystem stresses and a single critical soil acid load level may not accurately reflect ecosystem health risk when subjected to multiple, episodic environmental stress. For example, the Appalachian Mountains of western North Carolina receive some of the highest rates of acidic deposition in the eastern United States, but these levels are considered to be below the critical acid load (CAL) that would cause forest damage. However, the area experienced a moderate three-year drought from 1999 to 2002, and in 2001 red spruce (Picea rubens Sarg.) trees in the area began to die in large numbers. The initial survey indicated that the affected trees were killed by the southern pine beetle (Dendroctonus frontalis Zimm.). This insect is not normally successful at colonizing these tree species because the trees produce large amounts of oleoresin that exclude the boring beetles. Subsequent investigations revealed that long-term acid deposition may have altered red spruce forest structure and function. There is some evidence that elevated acid deposition (particularly nitrogen) reduced tree water uptake potential, oleoresin production, and caused the trees to become more susceptible to insect colonization during the drought period

  7. Droop Control of Solar PV, Grid and Critical Load using Suppressing DC Current Injection Technique without Battery Storage (United States)

    Dama Mr., Jayachandra; (Mrs. , Lini Mathew, Dr.; Srikanth Mr., G.


    This paper presents design of a sustainable solar Photo voltaic system for an Indian cities based residential/community house, integrated with grid, supporting it as supplementary sources, to meet energy demand of domestic loads. The role of renewable energy sources in Distributed Generation (DG) is increasingly being recognized as a supplement and an alternative to large conventional central power supply. Though centralized economic system that solely depends on cities is hampered due to energy deficiency, the use of solar energy in cities is never been tried widely due to technical inconvenience and high installation cost. To mitigate these problems, this paper proposes an optimized design of grid-tied PV system without storage which is suitable for Indian origin as it requires less installallation cost and supplies residential loads when the grid power is unavailable. The energy requirement is mainly fulfilled from PV energy module for critical load of a city located residential house and supplemented by grid/DG for base and peak load. The system has been developed for maximum daily household demand of 50kWp and can be scaled to any higher value as per requirement of individual/community building ranging from 50kWp to 60kWp as per the requirement. A simplified control system model has been developed to optimize and control flow of power from these sources. The simulation work, using MATLAB Simulink software for proposed energy management, has resulted in an optimal yield leading efficient power flow control of proposed system.

  8. Two critical issues in Langevin simulation of gas flows

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jun [James Weir Fluids Laboratory, Department of Mechanical and Aerospace Engineering, University of Strathclyde, Glasgow G1 1XJ, United Kingdom and State Key Laboratory of High Temperature Gas Dynamics, Institute of Mechanics, Chinese Academy of Sciences (China); Fan, Jing [State Key Laboratory of High Temperature Gas Dynamics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China)


    A stochastic algorithm based on the Langevin equation has been recently proposed to simulate rarefied gas flows. Compared with the direct simulation Monte Carlo (DSMC) method, the Langevin method is more efficient in simulating small Knudsen number flows. While it is well-known that the cell sizes and time steps should be smaller than the mean free path and the mean collision time, respectively, in DSMC simulations, the Langevin equation uses a drift term and a diffusion term to describe molecule movements, so no direct molecular collisions have to be modeled. This enables the Langevin simulation to proceed with a much larger time step than that in the DSMC method. Two critical issues in Langevin simulation are addressed in this paper. The first issue is how to reproduce the transport properties as that described by kinetic theory. Transport coefficients predicted by Langevin equation are obtained by using Green-Kubo formulae. The second issue is numerical scheme with boundary conditions. We present two schemes corresponding to small time step and large time step, respectively. For small time step, the scheme is similar to DSMC method as the update of positions and velocities are uncoupled; for large time step, we present an analytical solution of the hitting time, which is the crucial factor for accurate simulation. Velocity-Couette flow, thermal-Couette flow, Rayleigh-Bénard flow and wall-confined problem are simulated by using these two schemes. Our study shows that Langevin simulation is a promising tool to investigate small Knudsen number flows.

  9. Critical loads and steady-state chemistry for streams in the state of Maryland. (United States)

    Sverdrup, H; Warfvinge, P; Rabenhorst, M; Janicki, A; Morgan, R; Bowman, M


    The critical loads to streams, steady-state stream chemistry and catchment chemical weathering rate in 73 catchments has been determined in the state of Maryland, USA. It was calculated with the PROFILE model from chemical limits for biological indicators, soil mineralogy, soil texture, annual average temperature, average soil moisture, net long-term uptake of base cations and nitrogen to the vegetation, annual precipitation and runoff and deposition of sulphur and nitrogen precursors of acid deposition. The results show a full range of critical loads from very low values in the sensitive catchments of western Maryland and the Coastal Plain on the Chesapeake Bay, to insensitive catchments in the Fredrick Valley and Ridge and the Piedmont plain. The critical loads will be used as an input to an integrated regional assessment of the quantitative sensitivity of streams to acid rain, and the assessment of regional stream alkalinity response to different abatement strategies. The mapping of steady-state stream chemistry indicates that streams in Maryland are still acidfying under the present deposition load. Land-use seems to play an important role in maintaining neutral pH in many of the streams of Maryland.

  10. Diuretic response to colloid and crystalloid fluid loading in critically ill patients. (United States)

    Smorenberg, Annemieke; Groeneveld, A B Johan


    In the critically ill patient, fluid loading is commonly done to stabilise hemodynamics and increase diuresis, whereas the absence of diuresis may predispose to harmful overloading. The goal of the current study was to evaluate the diuretic response and determinants thereof upon crystalloid and colloid fluid loading. This is a substudy on 42 clinically hypovolemic, septic or non-septic patients without acute kidney injury, who were randomly assigned, after stratification for sepsis, to a 90-min fluid loading protocol with either 0.9% saline or a colloid solution (gelatin, hydroxyethyl starch 200/0.5 or albumin). Hemodynamics, biochemical parameters and diuresis were recorded. A response was defined by an increase in diuresis of >10% during fluid loading. Diuresis increased more during saline than colloid infusion, together with a decline in colloid osmotic pressure (COP) of plasma and less increase in plasma volume and global hemodynamics with saline, at similar fluid balance. Nine patients (82%) receiving saline had a diuretic response, compared to 13 patients (42%) receiving colloids (P = 0.04), and the response was not predicted by underlying condition, global hemodynamics, volume of fluid infused and COP. In critically ill patients with clinical hypovolemia, diuresis increases more during saline than colloid fluid loading, only partly dependent of a fall in plasma COP.

  11. Centaur engine gimbal friction characteristics under simulated thrust load (United States)

    Askew, J. W.


    An investigation was performed to determine the friction characteristics of the engine gimbal system of the Centaur upper stage rocket. Because the Centaur requires low-gain autopilots in order to meet all stability requirements for some configurations, control performance (response to transients and limit-cycle amplitudes) depends highly on these friction characteristics. Forces required to rotate the Centaur engine gimbal system were measured under a simulated thrust load of 66,723 N (15,000 lb) and in an altitude/thermal environment. A series of tests was performed at three test conditions; ambient temperature and pressure, ambient temperature and vacuum, and cryogenic temperature and vacuum. Gimbal rotation was controlled, and tests were performed in which rotation amplitude and frequency were varied by using triangular and sinusoidal waveforms. Test data revealed an elastic characteristic of the gimbal, independent of the input signal, which was evident prior to true gimbal sliding. The torque required to initiate gimbal sliding was found to decrease when both pressure and temperature decreased. Results from the low amplitude and low frequency data are currently being used in mathematically modeling the gimbal friction characteristics for Centaur autopilot performance studies.

  12. Demonstration of Load-Follow Simulation with VERA-CS and Standalone BISON

    Energy Technology Data Exchange (ETDEWEB)

    Stimpson, Shane G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)


    In this report, load-follow simulations using VERA-CS with one-way coupling to standalone BISON has been demonstrated including both a single rod with a full cycle of load-follow operations and a quarter-core model with a single month of load-follow.

  13. The effect of critically moving loads on the vibrations of soft soils and isolated railway tracks (United States)

    Auersch, L.


    The dynamic response of the railway track is strongly influenced by the underlying soil. For a soft soil and very high train speeds or for a very soft soil and regular train speeds, the train speed can be close to the speed of elastic waves in the soil. This paper presents a detailed study of the so-called "moving-load effect", i.e. an amplification of the dynamic response due to the load movement, for the tracks on soft soil. The analysis is carried out by evaluating the related integrals in the wavenumber domain. The influence of the load speed is quantified for a large set of parameters, showing that the effect on the soil vibration is reduced with increase of the frequency, track width and inverse wave velocity. Therefore, the moving-load effect associated with vibratory train loads is negligible whereas the amplification associated with the moving dead weight of the train can be significant. The strong moving-load effect on a perfectly homogeneous soil, however, can be strongly diminished by a layered or randomly varying soil situation. This theoretical result is affirmed by measurements at a test site in Germany where the trains run on a very soft soil at a near-critical speed. The results for soft soils are compared with experimental and theoretical results for a stiff soil. It is found that the influence of the stiffness of the soil is much stronger than the moving-load effect. This holds for the soil vibration as well as for the track vibration which both show a minor dependence on the load speed but a considerable dependence on the soil stiffness in theory and experiment. Railway tracks can include soft isolation elements such as rail pads, sleeper shoes and ballast mats. For these types of isolation elements and normal soil conditions, the influence of the load speed is usually negligible. There is only one isolation measure for which the moving load may be effective: a track which is constructed as a heavy mass-spring system. The resonance of this track

  14. Development of initial loading procedure for teicoplanin in critically ill patients with severe infections. (United States)

    Matsumoto, Kazuaki; Kanazawa, Naoko; Watanabe, Erika; Yokoyama, Yuta; Fukamizu, Tomohide; Shimodozono, Yoshihiro; Maeda, Chiharu; Yasuda, Tomotsugu; Kakihana, Yasuyuki; Ikawa, Kazuro; Morikawa, Norifumi; Takeda, Yasuo


    Methicillin-resistant Staphylococcus aureus (MRSA) is now endemic in many hospitals. Infection with MRSA is more frequent in the intensive care unit (ICU) than in general wards. Therefore, appropriate treatments for MRSA infections will lead to good outcomes in the ICU. Teicoplanin is an anti-MRSA agent. Recently, it was recommended at a new target trough concentration of 15-30 µg/mL. However, the initial loading procedure for teicoplanin to allow it to reach the target concentration promptly remains uncertain. Therefore, this study aimed to determine the appropriate initial loading procedure for teicoplanin in critically ill patients with severe infections. We performed a retrospective study in patients given teicoplanin in the ICU in order to determine the initial loading procedure to promptly reach the target trough concentration. We then evaluated the trough concentration on the third day after commencement of teicoplanin therapy. The mean loading dose and trough concentration were 11.5±1.0 mg/kg and 18.9±5.9 µg/mL, respectively. A correlation (r=0.45, p=0.046) was shown between teicoplanin loading dose and trough concentration. The correlation equation was trough concentration=2.563·loading dose -10.672. In the cases of 11.0 and 15.0 mg/kg for the loading dose, respectively, trough concentrations were 17.5 and 27.8 µg/mL. We suggested that an initial loading dose of 11-15 mg/kg every 12 h for 3 doses should be administered to promptly achieve the target trough concentration of 15-30 µg/mL on the third day after commencement of teicoplanin therapy in the ICU.

  15. Application of the theory of critical distances for the estimation of fracture under dynamic loading (United States)

    Terekhina, Alena; Kostina, Anastasiya; Plekhov, Oleg


    The theory of critical distances (TCD) is one of the most promising approaches to the prediction of material fracture, in which the stress concentration effect is taken into account. To date, the TCD has proven itself as a successful method for assessing the fatigue, static and dynamic strength of components with stress concentrators. However, for dynamic loading the theory was verified only on a small list of materials. This paper confirms that the application of the theory of critical distances to specimens made of structural steel 08X18H10T with different geometry features under dynamic deformation is a successful technique for estimating dynamic strength, and it allows a substantial reduction in the program of experiments in determining the ultimate loads.

  16. A simulation study of the critical ionization velocity process (United States)

    Machida, S.; Goertz, C. K.


    The critical ionization velocity process is studied by first investigating a coupled system of equations describing the production of several ion species and electrons by impact ionization, their collisions with neutrals, and the heating of electrons. Analytic relations derived from this were tested with the help of a particle simulation, including collisional processes between neutrals and plasma particles. It was found that resistive heating of electrons plays an important role when the density of the neutrals is high, and that electron heating due to lower hybrid waves is significant when the neutral density is low. In both cases, the control of the plasma production rate by the ratio of the beam velocity to the critical velocity was verified.

  17. Effects and empirical critical loads of Nitrogen for ecoregions of the United States (United States)

    Pardo, Linda H.; Robin-Abbott, Molly J.; Fenn, Mark E.; Goodale, Christine L.; Geiser, Linda H.; Driscoll, Charles T.; Allen, Edith B.; Baron, Jill S.; Bobbink, Roland; Bowman, William D.; Clark, C M; Emmett, B.; Gilliam, Frank S; Greaver, Tara L.; Hall, Sharon J; Lilleskov, Erik A.; Liu, Lingli; Lynch, Jason A.; Nadelhoffer, Knute J; Perakis, Steven; Stoddard, John L; Weathers, Kathleen C.; Dennis, Robin L.


    Human activity in the last century has increased nitrogen (N) deposition to a level that has caused or is likely to cause alterations to the structure and function of many ecosystems across the United States. We synthesized current research relating atmospheric N deposition to effects on terrestrial and freshwater ecosystems in the United States, and estimated associated empirical critical loads of N for several receptors: freshwater diatoms, mycorrhizal fungi, lichens, bryophytes, herbaceous plants, shrubs, and trees. Biogeochemical responses included increased N mineralization and nitrification, increased gaseous N losses, and increased N leaching. Individual species, population, and community responses included increased tissue N, physiological and nutrient imbalances, increased growth, altered root-shoot ratios, increased susceptibility to secondary stresses, altered fire regime, shifts in competitive interactions and community composition, changes in species richness and other measures of biodiversity, and increases in invasive species. The range of critical loads of nutrient N reported for U.S. ecoregions, inland surface waters, and freshwater wetlands is 1–39 kg N ha−1 yr−1, spanning the range of N deposition observed over most of the country. The empirical critical loads of N tend to increase in the following sequence: diatoms, lichens and bryophytes, mycorrhizal fungi, herbaceous plants and shrubs, trees.

  18. Nitrogen deposition and exceedance of critical loads for nutrient nitrogen in Irish grasslands. (United States)

    Henry, Jason; Aherne, Julian


    High resolution nitrogen (N) deposition maps were developed to assess the exceedance of empirical critical loads of nutrient N for grasslands in Ireland. Nitrogen emissions have remained relatively constant during the past 20 yrs and are projected to remain constant under current legislation. Total N deposition (estimated as wet nitrate [NO3(-)] and ammonium [NH4(+)] plus dry NO× and NH3) ranged from 2 to 22 kg Nha(-1)yr(-1) (mean=12 kg Nha(-1)yr(-1)) to grasslands. Empirical critical loads for nutrient N were set at 15 kg Nha(-1)yr(-1) for both acid and calcareous grasslands; exceedance was observed for ~35% (~2,311 km(2)) of mapped acid grasslands. In contrast, only ~9% of calcareous grasslands (~35 km(2)) received N deposition in excess of the critical load. Reduced N deposition (primarily dry NH3) represented the dominant form to grasslands (range 55-90%) owing to significant emissions associated with livestock (primarily cattle). The extent of exceedance in acid grasslands suggests that N deposition to this habitat type may lead to adverse impacts such as a decline in plant species diversity and soil acidification. Further, given that elevated N deposition was dominated by NH3 associated with agricultural emissions rather than long-range transboundary sources, future improvements in air quality need to be driven by national policies. © 2013.

  19. The development of an approach to assess critical loads of acidity for woodland habitats in Great Britain

    Directory of Open Access Journals (Sweden)

    S. J. Langan


    Full Text Available Alongside other countries that are signatories to the UNECE Convention Long Range Transboundary on Air Pollution, the UK is committed to reducing the impact of air pollution on the environment. To advise and guide this policy in relation to atmospheric emissions of sulphur and nitrogen, a critical load approach has been developed. To assess the potential impact of these pollutants on woodland habitats a steady state, simple mass balance model has been parameterised. For mineral soils, a Ca:Al ratio in soil solution has been used as the critical load indicator for potential damage. For peat and organic soils critical loads have been set according to a pH criterion. Together these approaches have been used with national datasets to examine the potential scale of acidification in woodland habitats across the UK. The results can be mapped to show the spatial variability in critical loads of the three principal woodland habitat types (managed coniferous, managed broadleaved/ mixed woodland and unmanaged woodland. The results suggest that there is a wide range of critical loads. The most sensitive (lowest critical loads are associated with managed coniferous followed by unmanaged woodland on peat soils. Calculations indicate that at steady state, acid deposition inputs reported for 1995–1997 result in a large proportion of all the woodland habitats identified receiving deposition loads in excess of their critical load; i.e. critical loads are exceeded. These are discussed in relation to future modelled depositions for 2010. Whilst significant widespread negative impacts of such deposition on UK woodland habitats have not been reported, the work serves to illustrate that if acid deposition inputs were maintained and projected emissions reductions not achieved, the long-term sustainability of large areas of woodland in the UK could be compromised. Keywords: critical loads, acid deposition, acidification, woodland, simple mass balance model

  20. Critical slowing down and error analysis in lattice QCD simulations

    Energy Technology Data Exchange (ETDEWEB)

    Virotta, Francesco


    In this work we investigate the critical slowing down of lattice QCD simulations. We perform a preliminary study in the quenched approximation where we find that our estimate of the exponential auto-correlation time scales as {tau}{sub exp}(a){proportional_to}a{sup -5}, where a is the lattice spacing. In unquenched simulations with O(a) improved Wilson fermions we do not obtain a scaling law but find results compatible with the behavior that we find in the pure gauge theory. The discussion is supported by a large set of ensembles both in pure gauge and in the theory with two degenerate sea quarks. We have moreover investigated the effect of slow algorithmic modes in the error analysis of the expectation value of typical lattice QCD observables (hadronic matrix elements and masses). In the context of simulations affected by slow modes we propose and test a method to obtain reliable estimates of statistical errors. The method is supposed to help in the typical algorithmic setup of lattice QCD, namely when the total statistics collected is of O(10){tau}{sub exp}. This is the typical case when simulating close to the continuum limit where the computational costs for producing two independent data points can be extremely large. We finally discuss the scale setting in N{sub f}=2 simulations using the Kaon decay constant f{sub K} as physical input. The method is explained together with a thorough discussion of the error analysis employed. A description of the publicly available code used for the error analysis is included.

  1. Ductile fracture simulation of SA508 Gr. 1a under LCF loading condition

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Hyun Suk; Kim, Yun Jae [Korea University, Seoul (Korea, Republic of); Kim, Jin Won [Chosun University, Gwangju (Korea, Republic of)


    In order to design and maintain piping system such as seismic accident, fracture mechanics analysis under seismic loading is important. For this reason, ductile fracture simulation under cyclic loading condition is very important in structural integrity analysis of pipeline and nuclear piping. The author have recently proposed a numerical method to simulate ductile tearing under quasi-static, dynamic loading conditions, based on the ductility exhaustion concept using the multi-axial fracture strain energy model. In this paper, the numerical method to simulate ductile tearing is extended to cyclic loading conditions. The presented method is applied to fracture toughness test under cyclic loading condition. This paper present a numerical method to simulate ductile tearing fracture toughness test under cyclic loading condition performed by Prof Kim. The proposed method is based on the stress-modified fracture strain energy model. To validate the method, simulated results of smooth bar and fracture toughness test under quasi-static loading condition are compared with experimental data. Using calibrated damage parameters, fracture toughness test under cyclic loading condition are simulated. The results shows that the proposed method predicts experimental data well.

  2. Effect of bidirectional loading on contact and force characteristics under a newly developed masticatory simulator with a dual-direction loading system. (United States)

    Singhatanadgit, Weerachai; Junkaew, Puttiporn; Singhatanadgid, Pairod


    Mechanical responses of the test specimen under bidirectional and unidirectional loading were investigated using a newly developed masticatory simulator. The simulator adopted a four-bar linkage mechanism to create both loading patterns. Scratch/occlusal contact characteristics, contact force profiles and the fracture of restored tooth samples were investigated. With bidirectional loading, which imitates the nature of human chewing cycle closer than the unidirectional loading does, the occlusal contact was ovoid in shape whereas a small circular area was observed from the test with unidirectional loading. The contact force profiles were also noticeably dependent on the loading patterns. Measured contact forces from bidirectional loading were more uniform than those from unidirectional loading. Bidirectional loading also induced the cuspal fracture with similar characteristics of natural cuspal fractures in humans. The differences of force characteristics between those of bidirectional and unidirectional loadings emphasize the importance of employing bidirectional loading in dental material testing.

  3. Validation of a Simplified Building Cooling Load Model Using a Complex Computer Simulation Model


    Stewart, Morgan Eugene


    Building energy simulation has become a useful tool for predicting cooling, heating and electrical loads for facilities. Simulation models have been validated throughout the years by comparing simulation results to actual measured values. The simulations have become more accurate as approaches were changed to be more comprehensive in their ability to model building features. These simulation models tend to require considerable experience in determining input parameters and large amounts of...

  4. Parallel implementation of the particle simulation method with dynamic load balancing: Toward realistic geodynamical simulation (United States)

    Furuichi, M.; Nishiura, D.


    Fully Lagrangian methods such as Smoothed Particle Hydrodynamics (SPH) and Discrete Element Method (DEM) have been widely used to solve the continuum and particles motions in the computational geodynamics field. These mesh-free methods are suitable for the problems with the complex geometry and boundary. In addition, their Lagrangian nature allows non-diffusive advection useful for tracking history dependent properties (e.g. rheology) of the material. These potential advantages over the mesh-based methods offer effective numerical applications to the geophysical flow and tectonic processes, which are for example, tsunami with free surface and floating body, magma intrusion with fracture of rock, and shear zone pattern generation of granular deformation. In order to investigate such geodynamical problems with the particle based methods, over millions to billion particles are required for the realistic simulation. Parallel computing is therefore important for handling such huge computational cost. An efficient parallel implementation of SPH and DEM methods is however known to be difficult especially for the distributed-memory architecture. Lagrangian methods inherently show workload imbalance problem for parallelization with the fixed domain in space, because particles move around and workloads change during the simulation. Therefore dynamic load balance is key technique to perform the large scale SPH and DEM simulation. In this work, we present the parallel implementation technique of SPH and DEM method utilizing dynamic load balancing algorithms toward the high resolution simulation over large domain using the massively parallel super computer system. Our method utilizes the imbalances of the executed time of each MPI process as the nonlinear term of parallel domain decomposition and minimizes them with the Newton like iteration method. In order to perform flexible domain decomposition in space, the slice-grid algorithm is used. Numerical tests show that our

  5. Atmospheric deposition and critical loads for nitrogen and metals in Arctic Alaska: Review and current status (United States)

    Linder, Greg L.; Brumbaugh, William G.; Neitlich, Peter; Little, Edward


    To protect important resources under their bureau’s purview, the United States National Park Service’s (NPS) Arctic Network (ARCN) has developed a series of “vital signs” that are to be periodically monitored. One of these vital signs focuses on wet and dry deposition of atmospheric chemicals and further, the establishment of critical load (CL) values (thresholds for ecological effects based on cumulative depositional loadings) for nitrogen (N), sulfur, and metals. As part of the ARCN terrestrial monitoring programs, samples of the feather moss Hylocomium splendens are being col- lected and analyzed as a cost-effective means to monitor atmospheric pollutant deposition in this region. Ultimately, moss data combined with refined CL values might be used to help guide future regulation of atmospheric contaminant sources potentially impacting Arctic Alaska. But first, additional long-term studies are needed to determine patterns of contaminant deposition as measured by moss biomonitors and to quantify ecosystem responses at particular loadings/ ranges of contaminants within Arctic Alaska. Herein we briefly summarize 1) current regulatory guidance related to CL values 2) derivation of CL models for N and metals, 3) use of mosses as biomonitors of atmospheric deposition and loadings, 4) preliminary analysis of vulnerabilities and risks associated with CL estimates for N, 5) preliminary analysis of existing data for characterization of CL values for N for interior Alaska and 6) implications for managers and future research needs.

  6. Finite Element Simulation of NiTi Umbrella-Shaped Implant Used on Femoral Head under Different Loadings

    Directory of Open Access Journals (Sweden)

    Reza Mehrabi


    Full Text Available In this study, an umbrella-shaped device that is used for osteonecrosis treatment is simulated. The femoral head is subjected to various complex loadings as a result of a person’s daily movements. Implant devices used in the body are made of shape memory alloy materials because of their remarkable resistance to wear and corrosion, good biocompatibility, and variable mechanical properties. Since this NiTi umbrella-shaped implant is simultaneously under several loadings, a 3-D model of shape memory alloy is utilized to investigate the behavior of the implant under different conditions. Shape memory and pseudo-elasticity behavior of NiTi is analyzed using a numerical model. The simulation is performed within different temperatures and in an isothermal condition with varied and complex loadings. The objective of this study is to evaluate the performance of the device under thermal and multi-axial forces via numerically study. Under tensile loading, the most critical points are on the top part of the implant. It is also shown that changes in temperature have a minor effect on the Von Mises stress. Applied forces and torques have significant influence on the femoral head. Simulations results indicate that the top portion of the umbrella is under the most stress when embedded in the body. Consequently, the middle, curved portion of the umbrella is under the least amount of stress.

  7. Nitrogen critical loads for alpine vegetation and soils in Rocky Mountain National Park. (United States)

    Bowman, William D; Murgel, John; Blett, Tamara; Porter, Ellen


    We evaluated the ecological thresholds associated with vegetation and soil responses to nitrogen (N) deposition, by adding NH(4)NO(3) in solution at rates of 5, 10 and 30 kg N ha(-1) yr(-1) to plots in a species rich dry meadow alpine community in Rocky Mountain National Park receiving ambient N deposition of 4 kg N ha(-1) yr(-1). To determine the levels of N input that elicited changes, we measured plant species composition annually, and performed one-time measurements of aboveground biomass and N concentrations, soil solution and resin bag inorganic N, soil pH, and soil extractable cations after 3 years of N additions. Our goal was to use these dose-response relationships to provide N critical loads for vegetation and soils for the alpine in Rocky Mountain National Park. Species richness and diversity did not change in response to the treatments, but one indicator species, Carex rupestris increased in cover from 34 to 125% in response to the treatments. Using the rate of change in cover for C. rupestris in the treatment and the ambient plots, and assuming the change in cover was due solely to N deposition, we estimated a N critical load for vegetation at 3 kg N ha(-1) yr(-1). Inorganic N concentrations in soil solution increased above ambient levels at input rates between 9 kg N ha(-1) yr(-1) (resin bags) and 14 kg N ha(-1) yr(-1) (lysimeters), indicating biotic and abiotic sinks for N deposition are exhausted at these levels. No changes in soil pH or extractable cations occurred in the treatment plots, indicating acidification had not occurred after 3 years. We conclude that N critical loads under 10 kg ha(-1) yr(-1) are needed to prevent future acidification of soils and surface waters, and recommend N critical loads for vegetation at 3 kg N ha(-1) yr(-1) as important for protecting natural plant communities and ecosystem services in Rocky Mountain National Park. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Simulations of Lithium-Based Neutron Coincidence Counter for Gd-Loaded Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Cowles, Christian C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kouzes, Richard T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Siciliano, Edward R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)


    The Department of Energy Office of Nuclear Safeguards and Security (NA-241) is supporting the project Lithium-Based Alternative Neutron Detection Technology Coincidence Counting for Gd-loaded Fuels at Pacific Northwest National Laboratory for the development of a lithium-based neutron coincidence counter for nondestructively assaying Gd loaded nuclear fuel. This report provides results from MCNP simulations of a lithium-based coincidence counter for the possible measurement of Gd-loaded nuclear fuel. A comparison of lithium-based simulations and UNCL-II simulations with and without Gd loaded fuel is provided. A lithium-based model, referred to as PLNS3A-R1, showed strong promise for assaying Gd loaded fuel.

  9. Simulating tokamak PFC performance using simultaneous dual beam particle loading with pulsed heat loading (United States)

    Sinclair, Gregory; Gonderman, Sean; Tripathi, Jitendra; Ray, Tyler; Hassanein, Ahmed


    The performance of plasma facing components (PFCs) in a fusion device are expected to change due to high flux particle loading during operation. Tungsten (W) is a promising PFC candidate material, due to its high melting point, high thermal conductivity, and low tritium retention. However, ion irradiation of D and He have each shown to diminish the thermal strength of W. This work investigates the synergistic effect between ion species, using dual beam irradiation, on the thermal response of W during ELM-like pulsed heat loading. Experiments studied three different loading conditions: laser, laser + He+, and laser + He+ + D+. 100 eV He+ and D+ exposures used a flux of 3.0-3.5 x 1020 m-2 s-1. ELM-like loading was applied using a pulsed Nd:YAG laser at an energy density of 0.38-1.51 MJ m-2 (3600 1 ms pulses at 1 Hz). SEM imaging revealed that laser + He+ loading at 0.76 MJ m-2 caused surface melting, inhibiting fuzz formation. Increasing the laser fluence decreased grain size and increased surface pore density. Thermally-enhanced migration of trapped gases appear to reflect resultant molten morphology. This work was supported by the National Science Foundation PIRE project.

  10. Loads Analysis of a Floating Offshore Wind Turbine Using Fully Coupled Simulation: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Jonkman, J. M.; Buhl, M. L., Jr.


    This paper presents the use of fully coupled aero-hydro-servo-elastic simulation tools to perform a loads analysis of a 5-MW offshore wind turbine supported by a barge with moorings, one of many promising floating platform concepts.

  11. Incorporating episodicity into estimates of Critical Loads for juvenile salmonids in Scottish streams

    Directory of Open Access Journals (Sweden)

    E. E. Bridcut


    Full Text Available Critical Load (CL methodology is currently used throughout Europe to assess the risks of ecological damage due to sulphur and nitrogen emissions. Critical acid neutralising capacity (ANCCRIT is used in CL estimates for freshwater systems as a surrogate for biological damage. Although UK CL maps presently use an ANC value of 0 μeq l-1, this value has been based largely on Norwegian lake studies, in which brown trout is chosen as a representative indicator organism. In this study, an ANC value specific for brown trout in Scottish streams was determined and issues were addressed such as salmon and trout sensitivity in streams, episodicity, afforestation and complicating factors such as dissolved organic carbon (DOC and labile aluminium (Al-L. Catchments with significant forest cover were selected to provide fishless sites and to provide catchment comparisons in unpolluted areas. Chemical factors were the primary determinant with land use a secondary determinant of the distribution of salmonid populations at the twenty-six study sites. ANC explained more variance in brown trout density than pH. The most significant index of episodicity was percent of time spent below an ANC of 0 μeq l-1. An ANCCRIT value of 39 μeq l-1 was obtained based on a 50% probability of brown trout occurrence. The use of this revised ANCCRIT value in the CL equation improved the relationship between trout status and exceedance of CLs. Uncertainties associated with variations in Al-L at any fixed ANCCRIT, particularly within forested catchments, and the role of DOC in modifying the toxicity of Al-L are discussed. Keywords: Critical Load, Critical acid neutralising capacity, brown trout, episodes, streams

  12. Finite element analysis on tooth and periodontal stress under simulated occlusal loads. (United States)

    Zhang, H; Cui, J-W; Lu, X L; Wang, M-Q


    The tooth stress elicited by occluding contact represents critical biomechanical information about dental health during chewing. Effects of occlusal contact on tooth stress remain obscure. In this study, a mandibular first molar finite element model was built from CT images. The effects of area size, location and direction of occlusal loading on both tooth and periodontal stresses were analysed. Results showed tooth and periodontal stress had drastically different patterns. Tooth stress value was much higher than periodontal stress value under the same task. Tooth stress concentration area and its value decreased from outside to inside. The Maximum Tooth Stress (MTS) always occurred at the loading site and a larger loading area elicited a smaller MTS value. The variation of MTS was larger when the fossa bottoms were inclined loaded than when the cusp tips were inclined loaded, larger when lingually loaded than when buccally loaded and larger when mesially loaded than when distally loaded. Distal loadings generally induced smaller Maximum Periodontal Stress (MPS) variations than the mesial loadings. These findings indicated exposure of the rational site(s) to occlusal contact should be helpful to achieve proper tooth and periodontal stress, thus to diminish loading associated structure problems. © 2017 John Wiley & Sons Ltd.

  13. Dissipative particle dynamics simulation on paclitaxel loaded PEO-PPO-PEO block copolymer micelles. (United States)

    Wang, Zhigao; Jiang, Jie


    Self-assembly behavior of the polymer drug loading micelle PEO-PPO-PEO was studied using dissipative particle dynamics (DPD) simulation method with various simulation steps. The distributions of drugs in polymer carriers were also investigated with different drug feed ratios. Polymer carriers distributed on the surface of the spherical micelle, and drugs were almost encapsulated in the inner of the micelle. Our simulation work demonstrates that the DPD simulation is effective to study the drug loaded systems and can give useful guidance on the design and preparation of new drug carriers with tailored properties.

  14. Construction and testing of the simulation polygon for the protection of critical information resources


    Корнієнко, Б. Я.; Галата, Л.П.


    In this article, the process of constructing an imitation polygon as a method for studying the behavior of the system of protection of critical information resources is considered. The graphical network simulator application is used to construct the simulation polygon. The functionality of the GNS3 package is explored. The main properties of the simulation ground of protection of critical information resources are considered. The testing of a built-up simulation ground for protecting critical...

  15. Simulation of Prestressed Concrete Sandwich Panels Subjected to Blast Loads (Preprint) (United States)


    AFRL-RX-TY-TP-2010-0014 PREPRINT SIMULATION OF PRESTRESSED CONCRETE SANDWICH PANELS SUBJECTED TO BLAST LOADS Charles M. Newberry and...NUMBER (Include area code) 01-FEB-2010 Conference Paper PREPRINT 01-JAN-2009-- 31-DEC-2009 Simulation of Prestressed Concrete Sandwich Panels Subjected... concrete , sandwich panels, simulation, LS-DYNA, blast, tilt-up panels U U U UU 14 Paul Sheppard Reset Simulation of Prestressed Concrete Sandwich

  16. Comparison among model estimates of critical loads of acidic deposition using different sources and scales of input data (United States)

    T.C. McDonnell; B.J. Cosby; T.J. Sullivan; S.G. McNulty; E.C. Cohen


    The critical load (CL) of acidic atmospheric deposition represents the load of acidity deposited from the atmosphere to the earth’s surface at which harmful acidification effects on sensitive biological receptors are thought to occur. In this study, the CL for forest soils was estimated for 27 watersheds throughout the United States using a steady-state mass balance...

  17. A modified approach for estimating the aquatic critical load of acid deposition in northern Saskatchewan, Canada (United States)

    Whitfield, Colin J.; Mowat, Aidan C.; Scott, Kenneth A.; Watmough, Shaun A.


    Acid-sensitive ecosystems are found in northern Saskatchewan, which lies downwind of major sulphur (S) and nitrogen (N) emissions sources associated with the oil sands extraction industry. In order to protect these ecosystems against acidification, tolerance to acid deposition must be quantified. The suitability of the central empirical relationship used in the Steady-State Water Chemistry (SSWC) model to predict historical sulphate (SO4) concentrations was investigated, and an alternate approach for determining aquatic critical loads of acidity (CL(A)) was employed for the study lakes (n = 260). Critical loads of acidity were often low, with median values of 12-16 mmolc m-2 yr-1, with the lower value reflecting a region-specific limit for acid-neutralizing capacity identified in this study. Uncertain levels of atmospheric deposition in the region, however, are problematic for characterizing acidification risk. Accurate S and chloride (Cl) deposition are needed to identify catchment sources (and sinks) of these elements in the new approach for CL(A) calculation. Likewise, accurate depiction of atmospheric deposition levels can prove useful for evaluation of lake runoff estimates on which estimates of CL(A) are contingent. While CL(A) are low and exceedance may occur according to projected increases in S deposition in the near-term, S retention appears to be an important feature in many catchments and risk of acidification may be overstated should long-term S retention be occurring in peatlands.

  18. Probing the structure and in silico stability of cargo loaded DNA icosahedra using MD simulations. (United States)

    Joshi, Himanshu; Bhatia, Dhiraj; Krishnan, Yamuna; Maiti, Prabal K


    Platonic solids such as polyhedra based on DNA have been deployed for multifarious applications such as RNAi delivery, biological targeting and bioimaging. All of these applications hinge on the capability of DNA polyhedra for molecular display with high spatial precision. Therefore high resolution structural models of such polyhedra are critical to widen their applications in both materials and biology. Here, we present an atomistic model of a well-characterized DNA icosahedron, with demonstrated versatile functionalities in biological systems. We study the structure and dynamics of this DNA icosahedron using fully atomistic molecular dynamics (MD) simulation in explicit water and ions. The major modes of internal motion have been identified using principal component analysis. We provide a quantitative estimate of the radius of gyration (R g ), solvent accessible surface area (SASA) and volume of the icosahedron which is essential to estimate its maximal cargo carrying capacity. Importantly, our simulation of gold nanoparticles (AuNPs) encapsulated within DNA icosahedra revealed enhanced stability of the AuNP loaded DNA icosahedra compared to empty icosahedra. This is consistent with the experimental results that show high yields of cargo-encapsulated DNA icosahedra that have led to its diverse applications for precision targeting. These studies reveal that the stabilizing interactions between the cargo and the DNA scaffold powerfully position DNA polyhedra as targetable nanocapsules for payload delivery. These insights can be exploited for precise molecular display for diverse biological applications.

  19. Pollution Critical Load Exceedance and an Extended Growing Season as Modulators of Red Spruce Radial Growth (United States)

    Kosiba, A. M.; Schaberg, P. G.; Engel, B. J.; Rayback, S. A.; Hawley, G. J.; Pontius, J.; Miller, E. K.


    Acidic sulfur (S) and nitrogen (N) deposition depletes cations such as calcium (Ca) from forest soils and has been linked to increases in foliar winter injury that led to the decline of red spruce (Picea rubens Sarg.) in the northeastern United States. We used results from a 30 m resolution steady-state S and N critical load exceedance model for New England to better understand the spatial connections between Ca depletion and red spruce productivity. To calculate exceedance, atmospheric deposition was estimated for a 5-year period (1984-1988) because tree health and productivity declines were expected to be most responsive to high acid loading. We examined how radial growth (basal area increment) of 441 dominant and co-dominant red spruce trees from 37 sites across Vermont and New Hampshire was related to modeled estimates of S and N critical load exceedance. We assessed growth using statistical models with exceedance as a source of variation, but which also included "year" and "elevation class" (to help account for climatic variability) and interactions among factors. Exceedance was significantly and negatively associated with mean growth for the study period (1951-2010) overall, and particularly for the 1980s and 2000s - periods of numerous and/or severe foliar winter injury events. However, climate-related sources of variation (year and elevation) accounted for most of the differences in growth over the chronology. Interestingly, recent growth for red spruce is now the highest recorded over our dendrochronological record for the species - suggesting that the factors shaping growth may be changing. Because red spruce is a temperate conifer that has the capacity to photosynthesize year-round, it is possible that warmer temperatures may be extending the functional growing season of the species thereby fostering increased growth. Data from elevational transects on Mount Mansfield (Vermont's tallest mountain) indicate that warmer spring, summer, fall and even winter

  20. Simulation model of load balancing in distributed computing systems (United States)

    Botygin, I. A.; Popov, V. N.; Frolov, S. G.


    The availability of high-performance computing, high speed data transfer over the network and widespread of software for the design and pre-production in mechanical engineering have led to the fact that at the present time the large industrial enterprises and small engineering companies implement complex computer systems for efficient solutions of production and management tasks. Such computer systems are generally built on the basis of distributed heterogeneous computer systems. The analytical problems solved by such systems are the key models of research, but the system-wide problems of efficient distribution (balancing) of the computational load and accommodation input, intermediate and output databases are no less important. The main tasks of this balancing system are load and condition monitoring of compute nodes, and the selection of a node for transition of the user’s request in accordance with a predetermined algorithm. The load balancing is one of the most used methods of increasing productivity of distributed computing systems through the optimal allocation of tasks between the computer system nodes. Therefore, the development of methods and algorithms for computing optimal scheduling in a distributed system, dynamically changing its infrastructure, is an important task.

  1. Susceptibility of forests in the northeastern USA to nitrogen and sulfur deposition: critical load exceedance and forest health (United States)

    N. Duarte; L.H. Pardo; M.J. Robin-Abbott


    The objectives of this study were to assess susceptibility to acidification and nitrogen (N) saturation caused by atmospheric deposition to northeastern US forests, evaluate the benefits and shortcomings of making critical load assessments using regional data, and assess the relationship between expected risk (exceedance) and forest health. We calculated the critical...

  2. The Effect of Computer Simulations on Acquisition of Knowledge and Cognitive Load: A Gender Perspective (United States)

    Kaheru, Sam J.; Kriek, Jeanne


    A study on the effect of the use of computer simulations (CS) on the acquisition of knowledge and cognitive load was undertaken with 104 Grade 11 learners in four schools in rural South Africa on the physics topic geometrical optics. Owing to the lack of resources a teacher-centred approach was followed in the use of computer simulations. The…

  3. Comparing measured with simulated vertical soil stress under vehicle load

    DEFF Research Database (Denmark)

    Keller, Thomas; Lamandé, Mathieu; Arvidsson, Johan

    in the soil profile at 0.3, 0.5 and 0.7 m depth was measured during wheeling at field capacity on five soils (13-66% clay). Stress propagation was then simulated with the semi-analytical model, using vertical stress at 0.1 m depth estimated from tyre characteristics as upper boundary condition, and v...

  4. Reliability of engineering methods of assessment the critical buckling load of steel beams (United States)

    Rzeszut, Katarzyna; Folta, Wiktor; Garstecki, Andrzej


    In this paper the reliability assessment of buckling resistance of steel beam is presented. A number of parameters such as: the boundary conditions, the section height to width ratio, the thickness and the span are considered. The examples are solved using FEM procedures and formulas proposed in the literature and standards. In the case of the numerical models the following parameters are investigated: support conditions, mesh size, load conditions, steel grade. The numerical results are compared with approximate solutions calculated according to the standard formulas. It was observed that for high slenderness section the deformation of the cross-section had to be described by the following modes: longitudinal and transverse displacement, warping, rotation and distortion of the cross section shape. In this case we face interactive buckling problem. Unfortunately, neither the EN Standards nor the subject literature give close-form formulas to solve these problems. For this reason the reliability of the critical bending moment calculations is discussed.

  5. Hydrodynamic simulations of microjetting from shock-loaded grooves (United States)

    Roland, C.; de Rességuier, T.; Sollier, A.; Lescoute, E.; Soulard, L.; Loison, D.


    The interaction of a shock wave with a free surface which has geometrical defects, such as cavities or grooves, may lead to the ejection of micrometric debris at velocities of km/s. This process can be involved in many applications, like pyrotechnics or industrial safety. Recent laser shock experiments reported elsewhere in this conference have provided some insight into jet formation as well as jet tip velocities for various groove angles and shock pressures. Here, we present hydrodynamic simulations of these experiments, in both 2D and 3D geometries, using both finite element method and smoothed particle hydrodynamics. Numerical results are compared to several theoretical predictions including the Richtmyer-Meshkov instabilities. The role of the elastic-plastic behavior on jet formation is illustrated. Finally, the possibility to simulate the late stage of jet expansion and fragmentation is explored, to evaluate the mass distribution of the ejecta and their ballistic properties, still essentially unknown in the experiments.

  6. Blast Load Simulator Experiments for Computational Model Validation: Report 2 (United States)


    uncertainty information in the form of confidence intervals for peak pressure and impulse result in a data set that can be used to evaluate the...simulations of these explosive events and their effects. These codes are continuously improving, but still require validation against experimental data to... data at several locations on the surfaces of the structure. The BLS is a highly tunable compressed gas-driven, closed-end shock tube designed to

  7. Transient simulations of nitrogen load for a coastal aquifer and embayment, Cape Cod, MA (United States)

    Colman, J.A.; Masterson, J.P.


    A time-varying, multispecies, modular, three-dimensional transport model (MT3DMS) was developed to simulate groundwater transport of nitrogen from increasing sources on land to the shore of Nauset Marsh, a coastal embayment of the Cape Cod National Seashore. Simulated time-dependent nitrogen loads at the coast can be used to correlate with current observed coastal eutrophic effects, to predict current and ultimate effects of development, and to predict loads resulting from source remediation. A time-varying nitrogen load, corrected for subsurface loss, was applied to the land subsurface in the transport model based on five land-use coverages documenting increasing development from 1951 to 1999. Simulated nitrogen loads to Nauset Marsh increased from 230 kg/yr before 1930 to 4390 kg/yr in 2001 to 7130 kg/yr in 2100, assuming future nitrogen sources constant at the 1999 land-use rate. The simulated nitrogen load per area of embayment was 5 times greater for Salt Pond, a eutrophic landward extension of Nauset Marsh, than for other Nauset Marsh areas. Sensitivity analysis indicated that load results were little affected by changes in vertical discretization and annual recharge but much affected by the nitrogen loss rate assumed for a kettle lake downgradient from a landfill.

  8. National implementation of the UNECE convention on long-range transboundary air pollution (effects). Pt. 2. Impacts and risk estimation, critical loads, biodiversity, dynamic modelling, critical level violation, material corrosion; Nationale Umsetzung UNECE-Luftreinhaltekonvention (Wirkungen). T. 2. Wirkungen und Risikoabschaetzungen Critical Loads, Biodiversitaet, Dynamische Modellierung, Critical Levels Ueberschreitungen, Materialkorrosion

    Energy Technology Data Exchange (ETDEWEB)

    Gauger, Thomas [Bundesforschungsanstalt fuer Landwirtschaft, Braunschweig (DE). Inst. fuer Agraroekologie (FAL-AOE); Stuttgart Univ. (Germany). Inst. fuer Navigation; Haenel, Hans-Dieter; Roesemann, Claus [Bundesforschungsanstalt fuer Landwirtschaft, Braunschweig (DE). Inst. fuer Agraroekologie (FAL-AOE); Nagel, Hans-Dieter; Becker, Rolf; Kraft, Philipp; Schlutow, Angela; Schuetze, Gudrun; Weigelt-Kirchner, Regine [OeKO-DATA Gesellschaft fuer Oekosystemanalyse und Umweltdatenmanagement mbH, Strausberg (Germany); Anshelm, Frank [Geotechnik Suedwest Frey Marx GbR, Bietigheim-Bissingen (Germany)


    The report on the implementation of the UNECE convention on long-range transboundary air pollution Pt.2 covers the following issues: The tasks of the NFC (National Focal Center) Germany including the ICP (international cooperative program) modeling and mapping and the expert panel for heavy metals. Results of the work for the multi-component protocol cover the initial data for the calculation of the critical loads following the mass balance method, critical loads for acid deposition, critical loads for nitrogen input, critical load violations (sulfur, nitrogen). The results of work for the heavy metal protocol cover methodology development and recommendations for ICO modeling and mapping in accordance with international development, contributions of the expert group/ task force on heavy metals (WGSR), data sets on the critical loads for lead, cadmium and mercury, and critical load violations (Pb, Cd, Hg). The results of work on the inclusion of biodiversity (BERN) cover data compilation, acquisition and integration concerning ecosystems, model validation and verification and the possible interpretation frame following the coupling with dynamic modeling. The future development and utilization of dynamic modeling covers model comparison, applicability, the preparation of a national data set and preparations concerning the interface to the BERN model.

  9. A non-coaxial critical state soil model and its application to simple shear simulations (United States)

    Yang, Yunming; Yu, H. S.


    The yield vertex non-coaxial theory is implemented into a critical state soil model, CASM (Int. J. Numer. Anal. Meth. Geomech. 1998; 22:621-653) to investigate the non-coaxial influences on the stress-strain simulations of real soil behaviour in the presence of principal stress rotations. The CASM is a unified clay and sand model, developed based on the soil critical state concept and the state parameter concept. Without loss of simplicity, it is capable of simulating the behaviour of sands and clays within a wide range of densities. The non-coaxial CASM is employed to simulate the simple shear responses of Erksak sand and Weald clay under different densities and initial stress states. Dependence of the soil behaviour on the Lode angle and different plastic flow rules in the deviatoric plane are also considered in the study of non-coaxial influences. All the predictions indicate that the use of the non-coaxial model makes the orientations of the principal stress and the principal strain rate different during the early stage of shearing, and they approach the same ultimate values with an increase in loading. These ultimate orientations are dependent on the density of soils, and independent of their initial stress states. The use of the non-coaxial model also softens the shear stress evolutions, compared with the coaxial model. It is also found that the ultimate shear strengths by using the coaxial and non-coaxial models are dependent on the plastic flow rules in the deviatoric plane. Copyright

  10. Monte Carlo Simulation of Extreme Traffic Loading on Short and Medium Span Bridges


    ENRIGHT, Bernard; O'Brien, Eugene J.


    The accurate estimation of site-specific lifetime extreme traffic load effects is an important element in the cost-effective assessment of bridges. A common approach is to use statistical distributions derived from weigh-in-motion measurements as the basis for Monte Carlo simulation of traffic loading. However, results are highly sensitive to the assumptions made, not just with regard to vehicle weights but also to axle configurations and gaps between vehicles. This paper presents a comprehen...

  11. Unsteady hydraulic simulation of the cavitating part load vortex rope in Francis turbines (United States)

    Brammer, J.; Segoufin, C.; Duparchy, F.; Lowys, P. Y.; Favrel, A.; Avellan, F.


    For Francis turbines at part load operation a helical vortex rope is formed due to the swirling nature of the flow exiting the runner. This vortex creates pressure fluctuations which can lead to power swings, and the unsteady loading can lead to fatigue damage of the runner. In the case that the vortex rope cavitates there is the additional risk that hydro-acoustic resonance can occur. It is therefore important to be able to accurately simulate this phenomenon to address these issues. In this paper an unsteady, multi-phase CFD model was used to simulate two part-load operating points, for two different cavitation conditions. The simulation results were validated with test-rig data, and showed very good agreement. These results also served as an input for FEA calculations and fatigue analysis, which are presented in a separate study.

  12. Application of simulated lidar scanning patterns to constrained Gaussian turbulence fields for load validation

    DEFF Research Database (Denmark)

    Dimitrov, Nikolay Krasimirov; Natarajan, Anand


    of this study, we assess the influence of the proposed method on the statistical uncertainty in wind turbine extreme and fatigue loads. The main conclusion is that introducing lidar measurements as turbulence constraints in load simulations may bring significant reduction in load and energy production...... uncertainty, not accounting for any additional uncertainty from real measurements. The constrained turbulence method is most efficient for prediction of energy production and loads governed by the turbulence intensity and the thrust force, while for other load components such as tower base side-to-side moment...... generated Gaussian turbulence fields in compliance with the Mann model for neutral stability. The expected efficiency of various scanning patterns is estimated by means of the explained variance associated with the constrained field. A numerical study is made using the HAWC2 aeroelastic software, whereby...

  13. Critical nitrogen deposition loads in high-elevation lakes of the western US inferred from paleolimnological records (United States)

    Saros, J.E.; Clow, D.W.; Blett, T.; Wolfe, A.P.


    Critical loads of nitrogen (N) from atmospheric deposition were determined for alpine lake ecosystems in the western US using fossil diatom assemblages in lake sediment cores. Changes in diatom species over the last century were indicative of N enrichment in two areas, the eastern Sierra Nevada, starting between 1960 and 1965, and the Greater Yellowstone Ecosystem, starting in 1980. In contrast, no changes in diatom community structure were apparent in lakes of Glacier National Park. To determine critical N loads that elicited these community changes, we modeled wet nitrogen deposition rates for the period in which diatom shifts first occurred in each area using deposition data spanning from 1980 to 2007. We determined a critical load of 1.4 kg N ha-1 year-1 wet N deposition to elicit key nutrient enrichment effects on diatom communities in both the eastern Sierra Nevada and the Greater Yellowstone Ecosystem. ?? 2010 Springer Science+Business Media B.V.

  14. Temporal downscaling of decadal sediment load estimates to a daily interval for use in hindcast simulations (United States)

    Ganju, N.K.; Knowles, N.; Schoellhamer, D.H.


    In this study we used hydrologic proxies to develop a daily sediment load time-series, which agrees with decadal sediment load estimates, when integrated. Hindcast simulations of bathymetric change in estuaries require daily sediment loads from major tributary rivers, to capture the episodic delivery of sediment during multi-day freshwater flow pulses. Two independent decadal sediment load estimates are available for the Sacramento/San Joaquin River Delta, California prior to 1959, but they must be downscaled to a daily interval for use in hindcast models. Daily flow and sediment load data to the Delta are available after 1930 and 1959, respectively, but bathymetric change simulations for San Francisco Bay prior to this require a method to generate daily sediment load estimates into the Delta. We used two historical proxies, monthly rainfall and unimpaired flow magnitudes, to generate monthly unimpaired flows to the Sacramento/San Joaquin Delta for the 1851-1929 period. This step generated the shape of the monthly hydrograph. These historical monthly flows were compared to unimpaired monthly flows from the modern era (1967-1987), and a least-squares metric selected a modern water year analogue for each historical water year. The daily hydrograph for the modern analogue was then assigned to the historical year and scaled to match the flow volume estimated by dendrochronology methods, providing the correct total flow for the year. We applied a sediment rating curve to this time-series of daily flows, to generate daily sediment loads for 1851-1958. The rating curve was calibrated with the two independent decadal sediment load estimates, over two distinct periods. This novel technique retained the timing and magnitude of freshwater flows and sediment loads, without damping variability or net sediment loads to San Francisco Bay. The time-series represents the hydraulic mining period with sustained periods of increased sediment loads, and a dramatic decrease after 1910

  15. Critical Care Performance in a Simulated Military Aircraft Cabin Environment (United States)


    significantly contribute cognitive performance in this study with the exception of Critical Care Time 14, Defibrillates 1st time. The regression for CRRT 14 with...this study with the exception of Critical Care Time 14, Defibrillates 1 t time. The regression for CRRT 14 with altitude and noise as was

  16. Empowering Critical Thinking Skills with Computerized Patient Simulators (United States)

    Farrar, Francisca Cisneros; Suggs, Leslie


    Students struggle with the mastery of critical thinking skills which are essential to their academic success. University faculty are challenged to create teaching strategies to help students build critical thinking skills. Nursing faculty at Austin Peay State University in Clarksville, Tennessee looked to research and technology for ways to…

  17. Critical thinking skills in nursing students: comparison of simulation-based performance with metrics. (United States)

    Fero, Laura J; O'Donnell, John M; Zullo, Thomas G; Dabbs, Annette DeVito; Kitutu, Julius; Samosky, Joseph T; Hoffman, Leslie A


    This paper is a report of an examination of the relationship between metrics of critical thinking skills and performance in simulated clinical scenarios. Paper and pencil assessments are commonly used to assess critical thinking but may not reflect simulated performance. In 2007, a convenience sample of 36 nursing students participated in measurement of critical thinking skills and simulation-based performance using videotaped vignettes, high-fidelity human simulation, the California Critical Thinking Disposition Inventory and California Critical Thinking Skills Test. Simulation-based performance was rated as 'meeting' or 'not meeting' overall expectations. Test scores were categorized as strong, average, or weak. Most (75.0%) students did not meet overall performance expectations using videotaped vignettes or high-fidelity human simulation; most difficulty related to problem recognition and reporting findings to the physician. There was no difference between overall performance based on method of assessment (P = 0.277). More students met subcategory expectations for initiating nursing interventions (P ≤ 0.001) using high-fidelity human simulation. The relationship between videotaped vignette performance and critical thinking disposition or skills scores was not statistically significant, except for problem recognition and overall critical thinking skills scores (Cramer's V = 0.444, P = 0.029). There was a statistically significant relationship between overall high-fidelity human simulation performance and overall critical thinking disposition scores (Cramer's V = 0.413, P = 0.047). Students' performance reflected difficulty meeting expectations in simulated clinical scenarios. High-fidelity human simulation performance appeared to approximate scores on metrics of critical thinking best. Further research is needed to determine if simulation-based performance correlates with critical thinking skills in the clinical setting. © 2010 The Authors. Journal of Advanced

  18. Expected load spectra of prototype Francis turbines in low-load operation using numerical simulations and site measurements (United States)

    Eichhorn, M.; Taruffi, A.; Bauer, C.


    The operators of hydropower plants are forced to extend the existing operating ranges of their hydraulic machines to remain competitive on the energy market due to the rising amount of wind and solar power. Faster response times and a higher flexibility towards part- and low-load conditions enable a better electric grid control and assure therefore an economic operation of the power plant. The occurring disadvantage is a higher dynamic excitation of affected machine components, especially Francis turbine runners, due to pressure pulsations induced by unsteady flow phenomena (e.g. draft tube vortex ropes). Therefore, fatigue analysis becomes more important even in the design phase of the hydraulic machines to evaluate the static and dynamic load in different operating conditions and to reduce maintenance costs. An approach including a one-way coupled fluid-structure interaction has been already developed using unsteady CFD simulations and transient FEM computations. This is now applied on two Francis turbines with different specific speeds and power ranges, to obtain the load spectra of both machines. The results are compared to strain gauge measurements on the according Francis turbines to validate the overall procedure.

  19. Effects of running with backpack loads during simulated gravitational transitions: Improvements in postural control (United States)

    Brewer, Jeffrey David

    The National Aeronautics and Space Administration is planning for long-duration manned missions to the Moon and Mars. For feasible long-duration space travel, improvements in exercise countermeasures are necessary to maintain cardiovascular fitness, bone mass throughout the body and the ability to perform coordinated movements in a constant gravitational environment that is six orders of magnitude higher than the "near weightlessness" condition experienced during transit to and/or orbit of the Moon, Mars, and Earth. In such gravitational transitions feedback and feedforward postural control strategies must be recalibrated to ensure optimal locomotion performance. In order to investigate methods of improving postural control adaptation during these gravitational transitions, a treadmill based precision stepping task was developed to reveal changes in neuromuscular control of locomotion following both simulated partial gravity exposure and post-simulation exercise countermeasures designed to speed lower extremity impedance adjustment mechanisms. The exercise countermeasures included a short period of running with or without backpack loads immediately after partial gravity running. A novel suspension type partial gravity simulator incorporating spring balancers and a motor-driven treadmill was developed to facilitate body weight off loading and various gait patterns in both simulated partial and full gravitational environments. Studies have provided evidence that suggests: the environmental simulator constructed for this thesis effort does induce locomotor adaptations following partial gravity running; the precision stepping task may be a helpful test for illuminating these adaptations; and musculoskeletal loading in the form of running with or without backpack loads may improve the locomotor adaptation process.

  20. Simulation of the stochastic wave loads using a physical modeling approach

    DEFF Research Database (Denmark)

    Liu, W.F.; Sichani, Mahdi Teimouri; Nielsen, Søren R.K.


    reliability or its uncertainty. Moreover applicability of the probability density evolution method on engineering problems faces critical difficulties when the system embeds too many random variables. Hence it is useful to devise a method which can make realization of the stochastic load processes with low...

  1. Assimilative capacity-based emission load management in a critically polluted industrial cluster. (United States)

    Panda, Smaranika; Shiva Nagendra, S M


    In the present study, a modified approach was adopted to quantify the assimilative capacity (i.e., the maximum emission an area can take without violating the permissible pollutant standards) of a major industrial cluster (Manali, India) and to assess the effectiveness of adopted air pollution control measures at the region. Seasonal analysis of assimilative capacity was carried out corresponding to critical, high, medium, and low pollution levels to know the best and worst conditions for industrial operations. Bottom-up approach was employed to quantify sulfur dioxide (SO2), nitrogen dioxide (NO2), and particulate matter (aerodynamic diameter PM10) emissions at a fine spatial resolution of 500 × 500 m(2) in Manali industrial cluster. AERMOD (American Meteorological Society/U.S. Environmental Protection Agency Regulatory Model), an U.S. Environmental Protection Agency (EPA) regulatory model, was used for estimating assimilative capacity. Results indicated that 22.8 tonnes/day of SO2, 7.8 tonnes/day of NO2, and 7.1 tonnes/day of PM10 were emitted from the industries of Manali. The estimated assimilative capacities for SO2, NO2, and PM10 were found to be 16.05, 17.36, and 19.78 tonnes/day, respectively. It was observed that the current SO2 emissions were exceeding the estimated safe load by 6.7 tonnes/day, whereas PM10 and NO2 were within the safe limits. Seasonal analysis of assimilative capacity showed that post-monsoon had the lowest load-carrying capacity, followed by winter, summer, and monsoon seasons, and the allowable SO2 emissions during post-monsoon and winter seasons were found to be 35% and 26% lower, respectively, when compared with monsoon season. The authors present a modified approach for quantitative estimation of assimilative capacity of a critically polluted Indian industrial cluster. The authors developed a geo-coded fine-resolution PM10, NO2, and SO2 emission inventory for Manali industrial area and further quantitatively estimated its season

  2. Extreme Value Predictions using Monte Carlo Simulations with Artificially Increased Load Spectrum

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher


    an approximation to the mean outcrossing rate. Better accuracy can be obtained by Monte Carlo simulations, but the necessary length of the time domain simulations for very low out-crossing rates might be prohibitively long. In such cases the property mentioned above for the FORM reliability index might be assumed...... to be valid in the Monte Carlo simulations, making it possible to increase the out-crossing rates and thus reduce the necessary length of the time domain simulations by applying a larger load spectrum than relevant from a design point of view. The mean out-crossing rate thus obtained can then afterwards...... be found using the First Order Reliability Method (FORM). The FORM analysis also shows that the reliability index is strictly inversely proportional to the square root of the magnitude of the load spectrum, irrespectively of the non-linearity in the system. However, the FORM analysis only gives...

  3. Accurate load prediction by BEM with airfoil data from 3D RANS simulations (United States)

    Schneider, Marc S.; Nitzsche, Jens; Hennings, Holger


    In this paper, two methods for the extraction of airfoil coefficients from 3D CFD simulations of a wind turbine rotor are investigated, and these coefficients are used to improve the load prediction of a BEM code. The coefficients are extracted from a number of steady RANS simulations, using either averaging of velocities in annular sections, or an inverse BEM approach for determination of the induction factors in the rotor plane. It is shown that these 3D rotor polars are able to capture the rotational augmentation at the inner part of the blade as well as the load reduction by 3D effects close to the blade tip. They are used as input to a simple BEM code and the results of this BEM with 3D rotor polars are compared to the predictions of BEM with 2D airfoil coefficients plus common empirical corrections for stall delay and tip loss. While BEM with 2D airfoil coefficients produces a very different radial distribution of loads than the RANS simulation, the BEM with 3D rotor polars manages to reproduce the loads from RANS very accurately for a variety of load cases, as long as the blade pitch angle is not too different from the cases from which the polars were extracted.

  4. Critical load during continuous and discontinuous training in swimming Wistar rats

    Directory of Open Access Journals (Sweden)

    P. Chimin


    Full Text Available The study aimed to verify the pattern of critical load (CL and anaerobic swim capacity (ASC during a twelve-week continuous program, after 3 and 9 days of detraining, and in a short-term retraining in swimming rats. Animals were distributed into four groups: control (CG, trained (TG, detrained 3 days (D3G and detrained 9 days (D9G. They were submitted to a CL test in a swimming exercise. TG group trained continuously during 12 weeks. D3G and D9G groups trained for five weeks, stopped for three and nine days, respectively, and came back to complete the training period. ANOVA two-way for repeated measures was used to compare data. All groups showed decline on CL during the twelve weeks of training, but TG showed higher CL values at the end of the twelve weeks (T: 7.03 ± 1.62% of body mass, p<0.05. ASC values did not have a regular pattern of change; there were no statistical difference in the end of the twelve weeks. This study showed that continuous training was able to keep CL values higher than the other groups, but detraining and a short-term retraining was not benefic for CL and ASC.

  5. Lichen-based critical loads for atmospheric nitrogen deposition in Western Oregon and Washington Forests, USA. (United States)

    Geiser, Linda H; Jovan, Sarah E; Glavich, Doug A; Porter, Matthew K


    Critical loads (CLs) define maximum atmospheric deposition levels apparently preventative of ecosystem harm. We present first nitrogen CLs for northwestern North America's maritime forests. Using multiple linear regression, we related epiphytic-macrolichen community composition to: 1) wet deposition from the National Atmospheric Deposition Program, 2) wet, dry, and total N deposition from the Communities Multi-Scale Air Quality model, and 3) ambient particulate N from Interagency Monitoring of Protected Visual Environments (IMPROVE). Sensitive species declines of 20-40% were associated with CLs of 1-4 and 3-9 kg N ha(-1)y(-1) in wet and total deposition. CLs increased with precipitation across the landscape, presumably from dilution or leaching of depositional N. Tight linear correlation between lichen and IMPROVE data suggests a simple screening tool for CL exceedance in US Class I areas. The total N model replicated several US and European lichen CLs and may therefore be helpful in estimating other temperate-forest lichen CLs. Published by Elsevier Ltd.

  6. Optical feather and foil for shape and dynamic load sensing of critical flight surfaces (United States)

    Black, Richard J.; Costa, Joannes M.; Faridian, Fereydoun; Moslehi, Behzad; Pakmehr, Mehrdad; Schlavin, Jon; Sotoudeh, Vahid; Zagrai, Andrei


    Future flight vehicles may comprise complex flight surfaces requiring coordinated in-situ sensing and actuation. Inspired by the complexity of the flight surfaces on the wings and tail of a bird, it is argued that increasing the number of interdependent flight surfaces from just a few, as is normal in an airplane, to many, as in the feathers of a bird, can significantly enlarge the flight envelope. To enable elements of an eco-inspired Dynamic Servo-Elastic (DSE) flight control system, IFOS is developing a multiple functionality-sensing element analogous to a feather, consisting of a very thin tube with optical fiber based strain sensors and algorithms for deducing the shape of the "feather" by measuring strain at multiple points. It is envisaged that the "feather" will act as a unit of sensing and/or actuation for establishing shape, position, static and dynamic loads on flight surfaces and in critical parts. Advanced sensing hardware and software control algorithms will enable the proposed DSE flight control concept. The hardware development involves an array of optical fiber based sensorized needle tubes for attachment to key parts for dynamic flight surface measurement. Once installed the optical fiber sensors, which can be interrogated over a wide frequency range, also allow damage detection and structural health monitoring.

  7. Simulation of electron-cloud heat load for the cold arcs of the Large Hadron Collider

    CERN Document Server

    Maury Cuna, Humberto; Rumolo, Giovanni; Zimmermann, Frank


    The heat load due to the electron cloud in the Large Hadron Collider (LHC) cold arcs is a concern for its performance near and beyond nominal beam current. We report the results of simulation studies, which examine the electron-cloud induced heat load for different values of low-energy electron reflectivity and secondary emission yield at injection energy, as well as at beam energies of 4 TeV and 7 TeV, for two different bunch spacing: 25 ns and 50 ns. Benchmarking the simulations against heat-load observations at different beam energies and bunch spacings allows an estimate of the secondary emission yield in the cold arcs of the LHC and of its evolution as a function of time.

  8. Planning for purging and loading of a newly constructed gas pipeline system using a pipeline simulator

    Energy Technology Data Exchange (ETDEWEB)

    Mohitpour, M.; Kazakoff, J.; Jenkins, A.; Montemurro, D. [TransCanada Corp., Calgary, AB (Canada)


    A brief review of purging and loading of a gas pipeline was presented with a summary of current industry practices. If purging is done when pipelines are put into service, it involves the displacement of air or nitrogen by high pressure natural gas into one end of the pipeline section. If purging is done when a pipeline goes out of service, it involves the displacement of natural gas by air or other neutral gases. Current practices give no consideration to minimize the emission of methane gas into the atmosphere. This paper described a simplified purging calculation method and a simulation technique using commercially available software for planning purging and loading operations of gas pipeline systems. The hydraulic-based simulation technique made it possible to minimize the gas to air interface and minimize the emission of methane gas. The simulation also helped to predict the timing of purging and loading of the pipeline. An example was presented of the newly constructed Mayakan Pipeline in Mexico to demonstrate how the process was developed. Simulation results were favourably compared with field data collected during the actual purging and loading of the pipeline. 11 refs., 5 tabs., 8 figs.

  9. Numerical simulation of hydrodynamic wave loading by a compressible two-phase flow method

    NARCIS (Netherlands)

    Wemmenhove, Rik; Luppes, Roelf; Veldman, Arthur; Bunnik, Tim


    Hydrodynamic wave loading on and in offshore structures is studied by carrying out numerical simulations. Particular attention is paid to complex hydrodynamic phenomena such as wave breaking and air entrapment. The applied CFD method, ComFLOW, solves the Navier–Stokes equations with an improved

  10. Design Load Case Analysis tools for aeroelastic wind turbine simulations with HAWC2

    DEFF Research Database (Denmark)


    , prepost and cluster tools are created by David R.S. Verelst. This repository holds a series of scripts and small libraries that aim to help with the process of creating, managing, and post processing design load cases (DLC's) simulations. Note that the work presented here has not been streamlined...

  11. Simulations under uncertainty for occupant safety for a vehicle subjected to a blast load

    NARCIS (Netherlands)

    Sun, J.; Vlahopoulos, N.; Stabryla, T.J.; Goetz, R.; Velde, R. van de


    One of the main threats to military vehicles originates from landmine blasts. In order to improve the survivability of the occupants it is important to design a military vehicle for increased occupant safety. Simulation technology that combines modeling of the blast loads from the landmine

  12. Erosion simulation of first wall beryllium armour under ITER transient heat loads (United States)

    Bazylev, B.; Janeschitz, G.; Landman, I.; Pestchanyi, S.; Loarte, A.


    The beryllium is foreseen as plasma facing armour for the first wall in the ITER in form of Be-clad blanket modules in macrobrush design with brush size about 8-10 cm. In ITER significant heat loads during transient events (TE) are expected at the main chamber wall that may leads to the essential damage of the Be armour. The main mechanisms of metallic target damage remain surface melting and melt motion erosion, which determines the lifetime of the plasma facing components. Melting thresholds and melt layer depth of the Be armour under transient loads are estimated for different temperatures of the bulk Be and different shapes of transient loads. The melt motion damages of Be macrobrush armour caused by the tangential friction force and the Lorentz force are analyzed for bulk Be and different sizes of Be-brushes. The damage of FW under radiative loads arising during mitigated disruptions is numerically simulated.

  13. High-Performance Kinetic Plasma Simulations with GPUs and load balancing (United States)

    Germaschewski, Kai; Ahmadi, Narges; Abbott, Stephen; Lin, Liwei; Wang, Liang; Bhattacharjee, Amitava; Fox, Will


    We will describe the Plasma Simulation Code (PSC), a modern particle-in-cell code with GPU support and dynamic load balancing capabilities. For 2-d problems, we achieve a speed-up of up to 6 × on the Cray XK7 ``Titan'' using its GPUs over the well-known VPIC code, which has been optimized for conventional CPUs with SIMD support. Our load-balancing algorithm employs a space-filling Hilbert-Peano curve to maintain locality and has shown to keep the load balanced within approximately 10% in production runs which otherwise slow down up to 5 × with only static load balancing. PSC is based on the libmrc computational framework, which also supports explicit and implicit time integration of fluid plasma models. Applications include magnetic reconnection in HED plasmas, particle acceleration in space plasmas and the nonlinear evolution of anisotropy-based kinetic instabilities like the mirror mode.

  14. Wear simulation of total knee prostheses using load and kinematics waveforms from stair climbing. (United States)

    Abdel-Jaber, Sami; Belvedere, Claudio; Leardini, Alberto; Affatato, Saverio


    Knee wear simulators are meant to perform load cycles on knee implants under physiological conditions, matching exactly, if possible, those experienced at the replaced joint during daily living activities. Unfortunately, only conditions of low demanding level walking, specified in ISO-14243, are used conventionally during such tests. A recent study has provided a consistent knee kinematic and load data-set measured during stair climbing in patients implanted with a specific modern total knee prosthesis design. In the present study, wear simulation tests were performed for the first time using this data-set on the same prosthesis design. It was hypothesised that more demanding tasks would result in wear rates that differ from those observed in retrievals. Four prostheses for total knee arthroplasty were tested using a displacement-controlled knee wear simulator for two million cycles at 1.1 Hz, under kinematics and load conditions typical of stair climbing. After simulation, the corresponding damage scars on the bearings were qualified and compared with equivalent explanted prostheses. An average mass loss of 20.2±1.5 mg was found. Scanning digital microscopy revealed similar features, though the explant had a greater variety of damage modes, including a high prevalence of adhesive wear damage and burnishing in the overall articulating surface. This study confirmed that the results from wear simulation machines are strongly affected by kinematics and loads applied during simulations. Based on the present results for the full understanding of the current clinical failure of knee implants, a more comprehensive series of conditions are necessary for equivalent simulations in vitro. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Assessment of Nitrogen deposition effects and empirical critical loads of Nitrogen for ecoregions of the United States (United States)

    L.H. Pardo; M.J. Robin-Abbott; C.T., eds. Driscoll


    This report synthesizes current research relating atmospheric nitrogen (N) deposition to effects on terrestrial and aquatic ecosystems in the United States and to identify empirical critical loads for atmospheric N deposition. The report evaluates the following receptors: freshwater diatoms, mycorrhizal fungi and other soil microbes, lichens, herbaceous plants, shrubs...

  16. Using fire risk and species loss to set critical loads for nitrogen deposition in southern California shrublands (United States)

    E.B. Allen; L.E. Rao; G. Tonnesen; R.F. Johnson; M.E. Fenn; A. Bytnerowicz


    Southern California deserts and coastal sage scrub (CSS) are undergoing vegetation-type conversion to exotic annual grassland, especially in regions downwind of urban areas that receive high nitrogen (N), primarily as dry deposition. To determine critical loads (CLs) of N that cause negative impacts, we measured plant and soil responses along N deposition gradients,...

  17. Critical loads for acidity and nitrogen for Dutch forests on a 1 km x 1 km grid

    NARCIS (Netherlands)

    Vries, de W.


    Critical loads were derived using a one-layer steady-state model that includes mineral weathering, nutrient uptake, nitrogen transformations, and an acceptable leaching rate of acidity or nitrogen. Values were calculated for combinations of 12 tree species and 23 soil types. Acceptable leaching

  18. Optimal distributed generation placement in distribution system to improve reliability and critical loads pick up after natural disasters

    Directory of Open Access Journals (Sweden)

    Galiveeti Hemakumar Reddy


    Full Text Available The increase in frequency of natural disasters has necessitated the need of resilient distribution systems. Natural disasters lead to severe damage of power system infrastructure and the main grid may not be available to serve the loads. The integration of distributed generation (DG into distribution system partially restores the loads after natural disasters and improves the reliability during normal operating conditions. After a natural disaster, objective of the system operators is to restore the critical loads as a priority. This enables the need of considering critical load pick up as an objective function while placing the DGs. A location based constraint is, thus, required to make sure the DGs are available to pick up the loads after natural disasters. Fuzzy multi criteria decision making (FMCDM approach is used in this work to rank the load points and locations/feeder sections. This paper uses particle swarm optimization (PSO to evaluate the optimal size and location of DGs using the proposed objective function. The obtained results are compared with the results of reliability as an objective function.

  19. Measuring working memory load effects on electrophysiological markers of attention orienting during a simulated drive. (United States)

    Ross, Veerle; Vossen, Alexandra Y; Smulders, Fren T Y; Ruiter, Robert A C; Brijs, Tom; Brijs, Kris; Wets, Geert; Jongen, Ellen M M


    Intersection accidents result in a significant proportion of road fatalities, and attention allocation likely plays a role. Attention allocation may depend on (limited) working memory (WM) capacity. Driving is often combined with tasks increasing WM load, consequently impairing attention orienting. This study (n = 22) investigated WM load effects on event-related potentials (ERPs) related to attention orienting. A simulated driving environment allowed continuous lane-keeping measurement. Participants were asked to orient attention covertly towards the side indicated by an arrow, and to respond only to moving cars appearing on the attended side by pressing a button. WM load was manipulated using a concurrent memory task. ERPs showed typical attentional modulation (cue: contralateral negativity, LDAP; car: N1, P1, SN and P3) under low and high load conditions. With increased WM load, lane-keeping performance improved, while dual task performance degraded (memory task: increased error rate; orienting task: increased false alarms, smaller P3). Practitioner Summary: Intersection driver-support systems aim to improve traffic safety and flow. However, in-vehicle systems induce WM load, increasing the tendency to yield. Traffic flow reduces if drivers stop at inappropriate times, reducing the effectiveness of systems. Consequently, driver-support systems could include WM load measurement during driving in the development phase.

  20. A comparison of educational strategies for the acquisition of nursing student's performance and critical thinking: simulation-based training vs. integrated training (simulation and critical thinking strategies). (United States)

    Zarifsanaiey, Nahid; Amini, Mitra; Saadat, Farideh


    There is a need to change the focus of nursing education from traditional teacher-centered training programs to student-centered active methods. The integration of the two active learning techniques will improve the effectiveness of training programs. The objective of this study is to compare the effects of the integrated training (simulation and critical thinking strategies) and simulation-based training on the performance level and critical thinking ability of nursing students. The present quasi-experimental study was performed in 2014 on 40 students who were studying practical nursing principles and skills course in the first half of the academic year in Shiraz University of Medical Sciences. Students were randomly divided into control (n = 20) and experimental (n = 20) groups. After training students through simulation and integrated education (simulation and critical thinking strategies), the students' critical thinking ability and performance were evaluated via the use of California Critical Thinking Ability Questionnaire B (CCTST) and Objective Structured Clinical Examination (OSCE) comprising 10 stations, respectively. The external reliability of the California Critical Thinking questionnaire was reported by Case be between 0.78 and 0.80 and the validity of OSCE was approved by 5 members of the faculty. Furthermore, by using Split Half method (the correlation between odd and even stations), the reliability of the test was approved with correlation coefficient of 0.66. Data were analyzed using t-test and Mann-Whitney test. A significance level of 0.05 was considered to be statistically significant. The mean scores of the experimental group performance level were higher than the mean score of the control group performance level. This difference was statistically significant and students in the experimental group in OSCE stations had significantly higher performance than the control group (P students' performance level was increased by the

  1. Molecular dynamics simulation of functionalized graphene surface for high efficient loading of doxorubicin (United States)

    Mirhosseini, Mohammad Masoud; Rahmati, Mahmoud; Zargarian, Seyed Shahrooz; Khordad, Reza


    Molecular dynamics simulations are performed to study the design and optimization of nanocarriers with high drug loading capacity. Functionalized graphene is considered as the nominated high capacity drug carrier and Dox as the drug model. The graphene surface functionalized with hydroxyl (- OH), carboxyl (- COOH), methyl (- CH3) and amine (- NH2) groups and their associated properties are investigated. The simulation results are illustrated that G - COOH surface absorbs Dox more effectively in comparison to other functionalized graphene surfaces due to the higher binding energy of carboxylic groups and the model drug. The effect of hydrogen bonding, temperature and surface porosity are also evaluated. The results show that binding energy and the solubility parameter are temperature-dependent. The simulation results in this present work reveal the underlying mechanisms of Dox loading on neat and functionalized graphene surfaces may be employed to design better graphene-based nanocarriers for the Dox delivery applications.

  2. Adaptive complementary fuzzy self-recurrent wavelet neural network controller for the electric load simulator system

    Directory of Open Access Journals (Sweden)

    Wang Chao


    Full Text Available Due to the complexities existing in the electric load simulator, this article develops a high-performance nonlinear adaptive controller to improve the torque tracking performance of the electric load simulator, which mainly consists of an adaptive fuzzy self-recurrent wavelet neural network controller with variable structure (VSFSWC and a complementary controller. The VSFSWC is clearly and easily used for real-time systems and greatly improves the convergence rate and control precision. The complementary controller is designed to eliminate the effect of the approximation error between the proposed neural network controller and the ideal feedback controller without chattering phenomena. Moreover, adaptive learning laws are derived to guarantee the system stability in the sense of the Lyapunov theory. Finally, the hardware-in-the-loop simulations are carried out to verify the feasibility and effectiveness of the proposed algorithms in different working styles.

  3. Axiomatic safety-critical assessment process (ASCAP) simulation methodology

    Energy Technology Data Exchange (ETDEWEB)

    Kaufman, L.M.; Giras, T.C. [Virginia Univ., Charlottesville, VA (United States). Center for Safety-Critical Ssytems


    The ASCAP simulation methodology models continuous train movement using a hybrid simulation consisting of both time and event driven portions. The actual train movement is predicated upon the solution of a series of discrete equations to determine its velocity, acceleration and braking profile at a specific time in tandem with the behavior of the train crew and the dispatcher agents in relationship to the behavioral states of the various stationary and mobile objects that a given train encounters. From this hybrid simulation, it is possible to generate accident scenarios. By performing multiple experiments to collect data for various accident scenarios, it will be possible to statistically quantify the risk associated with the various accident scenarios that are identified. (orig.)

  4. Prediction of fatique crack growth under flight-simulation loading with the modified CORPUS model (United States)

    Padmadinata, U. H.; Schijve, J.


    The CORPUS (Computation Of Retarded Propagation Under Spectrum loading) crack growth prediction model for variable-amplitude loading, as introduced by De Koning, was based on crack closure. It includes a multiple-overload effect and a transition from plane strain to plane stress. In the modified CORPUS model an underload affected zone (ULZ) is introduced, which is significant for flight-simulation loading in view of the once per flight compressive ground load. The ULZ is associated with reversed plastic deformation induced by the underloads after crack closure has already occurred. Predictions of the crack growth fatigue life are presented for a large variety of flight-simulation test series on 2024-T3 sheet specimens in order to reveal the effects of a number of variables: the design stress level, the gust spectrum severity, the truncation level (clipping), omission of small cycles, and the ground stress level. Tests with different load sequences are also included. The trends of the effects induced by the variables are correctly predicted. The quantitative agreement between the predictions and the test results is also satisfactory.

  5. Utilizing a Simulation Exercise to Illustrate Critical Inventory Management Concepts (United States)

    Umble, Elisabeth; Umble, Michael


    Most undergraduate business students simply do not appreciate the elegant mathematical beauty of inventory models. So how does an instructor capture students' interest and keep them engaged in the learning process when teaching inventory management concepts? This paper describes a competitive and energizing in-class simulation game that introduces…

  6. Effect of cognitive load on speech prosody in aviation: Evidence from military simulator flights. (United States)

    Huttunen, Kerttu; Keränen, Heikki; Väyrynen, Eero; Pääkkönen, Rauno; Leino, Tuomo


    Mental overload directly affects safety in aviation and needs to be alleviated. Speech recordings are obtained non-invasively and as such are feasible for monitoring cognitive load. We recorded speech of 13 military pilots while they were performing a simulator task. Three types of cognitive load (load on situation awareness, information processing and decision making) were rated by a flight instructor separately for each flight phase and participant. As a function of increased cognitive load, the mean utterance-level fundamental frequency (F0) increased, on average, by 7 Hz and the mean vocal intensity increased by 1 dB. In the most intensive simulator flight phases, mean F0 increased by 12 Hz and mean intensity, by 1.5 dB. At the same time, the mean F0 range decreased by 5 Hz, on average. Our results showed that prosodic features of speech can be used to monitor speaker state and support pilot training in a simulator environment. Copyright © 2010 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  7. Investigation of the dependency of wind turbine loads on the simulation time

    DEFF Research Database (Denmark)

    Tibaldi, Carlo; Henriksen, Lars Christian; Bak, Christian


    In this work the dependency of several wind turbine parameters with respect to the length of simulations used for their evaluation is investigated. The analysis is performed by computing the parameters with a different number of turbulent wind simulations, therefore simulation time, and repeating...... the computation with different turbulence realizations. The repetition of the computation is performed to identify the scatter of the parameters for a given number of turbulent seeds due to the different turbulence realization. The dependency on the simulation time of load variations due to changes...... in the collective pitch controller tuning is also investigated. Results show a significantly high dependency of the parameters and their variations on the turbulent wind realization. This dependency makes the use of turbulent wind simulation results not reliable for numerical optimization purposes....

  8. Fluconazole dosing predictions in critically-ill patients receiving prolonged intermittent renal replacement therapy: a Monte Carlo simulation approach. (United States)

    Gharibian, Katherine N; Mueller, Bruce A


    Fluconazole is a renally-eliminated antifungal commonly used to treat Candida species infections. In critically-ill patients receiving prolonged intermittent renal replacement therapy (PIRRT), limited pharmacokinetic (PK) data are available to guide fluconazole dosing. We used previously-published fluconazole clearance data and PK data of critically-ill patients with acute kidney injury to develop a PK model with the goal of determining a therapeutic dosing regimen for critically-ill patients receiving PIRRT. Monte Carlo simulations were performed to create a virtual cohort of patients receiving different fluconazole dosing regimens. Plasma drug concentration-time profiles were evaluated on the probability of attaining a mean 24-hour area under the drug concentration-time curve to minimum inhibitory concentration ratio (AUC24h : MIC) of 100 during the initial 48 hours of antifungal therapy. At the susceptibility breakpoint of Candida albicans (2 mg/L), 93 - 96% of simulated subjects receiving PIRRT attained the pharmacodynamic target with a fluconazole 800-mg loading dose plus 400 mg twice daily (q12h or pre and post PIRRT) regimen. Monte Carlo simulations of a PK model of PIRRT provided a basis for the development of an informed fluconazole dosing recommendation when PK data was limited. This finding should be validated in the clinical setting.

  9. Recently surveyed lakes in northern Manitoba and Saskatchewan, Canada: characteristics and critical loads of acidity

    Directory of Open Access Journals (Sweden)

    Isaac WONG


    Full Text Available Based on minimal information, lakes in the western Canadian provinces of Manitoba (MB and Saskatchewan (SK have long been considered unaffected by acid rain. However, emissions of acidifying pollutants from MB smelters and oil sand processing in Alberta (AB may pose a developing threat. Surveys of 347 lakes located on geologically sensitive terrain in northern MB and SK were conducted to assess their acidification sensitivity and status. The survey domain (~193,000 km2 contained 81,494 lakes ≥1 ha in area. Small lakes dominated the inventory in terms of numbers, and large lakes dominated in terms of area. Survey lakes were selected using a stratified-random sampling design in 10 sampling blocks within the overall survey domain. Few lakes had pH <6, and only three (all in SK were acidic, i.e., Gran Alkalinity (Alk <0 μeq L–1. A broad range in lake sensitivity was apparent, and very sensitive lakes (low specific conductance, base cations and Alk were present in all sampling blocks. Dissolved organic carbon (DOC was an important constituent of many lakes. Critical loads (CL of acidity calculated using the Steady-State Water Chemistry model (SSWC revealed extremely low 5th percentile values for every block (range 1.9 to 52.7 eq ha–1 y–1. Block CL exceedances calculated using estimated S and N deposition for 2002 ranged from 54.5 to 909 eq ha–1 y–1. The largest exceedances were for sampling blocks located near smelter sources or downwind of the oil sands. Lake chemistry revealed by our surveys was compared to others conducted both nearby and outside Canada.

  10. Determination of bridge lifetime dynamic amplification factor using finite element analysis of critical loading scenarios


    González, Arturo; Rattigan, Paraic; O'Brien, Eugene J.; Caprani, Colin C.


    The development of accurate codes for the design of bridges and the evaluation of existing structures requires adequate assessment of heavy traffic loading and also the dynamic interaction that may occur as this traffic traverses the structure. Current approaches generally first calculate characteristic static load effect and then apply an amplification factor to allow for dynamics. This neglects the significantly-reduced probability of both high static loading and high dynamic amplific...

  11. Simulating pile load-settlement behavior from CPT data using intelligent computing (United States)

    Alkroosh, I.; Nikraz, H.


    Analysis of pile load-settlement behavior is a complex problem due to the participation of many factors involved. This paper presents a new procedure based on artificial neural networks (ANNs) for simulating the load-settlement behavior of pile foundations embedded in sand and mixed soils (subjected to axial loads). Three ANN models have been developed, a model for bored piles and two other models for driven piles (a model for each of concrete and steel piles). The data used for development of the ANN models is collected from the literature and comprise a series of in-situ piles load tests as well as cone penetration test (CPT) results. The data of each model is divided into two subsets: Training set for model calibration and independent validation set for model verification. Predictions from the ANN models are compared with the results of experimental data and with predictions of number of currently adopted load-transfer methods. Statistical analysis is used to verify the performance of the models. The results indicate that the ANN model performs very well and able to predict the pile load-settlement behaviour accurately.

  12. Modeling and Depletion Simulations for a High Flux Isotope Reactor Cycle with a Representative Experiment Loading

    Energy Technology Data Exchange (ETDEWEB)

    Chandler, David [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Reactor and Nuclear Systems Division; Betzler, Ben [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Reactor and Nuclear Systems Division; Hirtz, Gregory John [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Reactor and Nuclear Systems Division; Ilas, Germina [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Reactor and Nuclear Systems Division; Sunny, Eva [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Reactor and Nuclear Systems Division


    The purpose of this report is to document a high-fidelity VESTA/MCNP High Flux Isotope Reactor (HFIR) core model that features a new, representative experiment loading. This model, which represents the current, high-enriched uranium fuel core, will serve as a reference for low-enriched uranium conversion studies, safety-basis calculations, and other research activities. A new experiment loading model was developed to better represent current, typical experiment loadings, in comparison to the experiment loading included in the model for Cycle 400 (operated in 2004). The new experiment loading model for the flux trap target region includes full length 252Cf production targets, 75Se production capsules, 63Ni production capsules, a 188W production capsule, and various materials irradiation targets. Fully loaded 238Pu production targets are modeled in eleven vertical experiment facilities located in the beryllium reflector. Other changes compared to the Cycle 400 model are the high-fidelity modeling of the fuel element side plates and the material composition of the control elements. Results obtained from the depletion simulations with the new model are presented, with a focus on time-dependent isotopic composition of irradiated fuel and single cycle isotope production metrics.

  13. Effects of rotor location, coning, and tilt on critical loads in large wind turbines (United States)

    Spera, D. A.; Janetzke, D. C.


    Several large (1500 kW) horizontal rotor configurations were analyzed to determine the effects on dynamic loads of upwind downwind rotor locations, coned and radial blade positions, and tilted and horizontal rotor axis positions. Loads were calculated for a range of wind velocities at three locations in the structure: (1) the blade shank; (2) the hub shaft; and (3) the yaw drive. Blade axis coning and rotor axis tilt were found to have minor effects on loads. However, locating the rotor upwind of the tower significantly reduced loads at all locations analyzed.

  14. A PFC3D-based numerical simulation of cutting load for lunar rock simulant and experimental validation (United States)

    Li, Peng; Jiang, Shengyuan; Tang, Dewei; Xu, Bo


    For sake of striking a balance between the need of drilling efficiency and the constrains of power budget on the moon, the penetrations per revolution of drill bit are generally limited in the range around 0.1 mm, and besides the geometric angle of the cutting blade need to be well designed. This paper introduces a simulation approach based on PFC3D (particle flow code 3 dimensions) for analyzing the cutting load feature on lunar rock simulant, which is derived from different geometric-angle blades with a small cutting depth. The mean values of the cutting force of five blades in the survey region (four on the boundary points and one on the center point) are selected as the macroscopic responses of model. The method of experimental design which includes Plackett-Burman (PB) design and central composite design (CCD) method is adopted in the matching procedure of microparameters in PFC model. Using the optimization method of enumeration, the optimum set of microparameters is acquired. Then, the experimental validation is implemented by using other twenty-five blades with different geometric angles, and the results from both simulations and laboratory tests give fair agreements. Additionally, the rock breaking process cut by different blades are quantified from simulation analysis. This research provides the theoretical support for the refinement of the rock cutting load prediction and the geometric design of cutting blade on the drill bit.

  15. Improving Middle School Students’ Critical Thinking Skills Through Reading Infusion-Loaded Discovery Learning Model in the Science Instruction (United States)

    Nuryakin; Riandi


    A study has been conducted to obtain a depiction of middle school students’ critical thinking skills improvement through the implementation of reading infusion-loaded discovery learning model in science instruction. A quasi-experimental study with the pretest-posttest control group design was used to engage 55 eighth-year middle school students in Tasikmalaya, which was divided into the experimental and control group respectively were 28 and 27 students. Critical thinking skills were measured using a critical thinking skills test in multiple-choice with reason format questions that administered before and after a given instruction. The test was 28 items encompassing three essential concepts, vibration, waves and auditory senses. The critical thinking skills improvement was determined by using the normalized gain score and statistically analyzed by using Mann-Whitney U test.. The findings showed that the average of students’ critical thinking skills normalized gain score of both groups were 59 and 43, respectively for experimental and control group in the medium category. There were significant differences between both group’s improvement. Thus, the implementation of reading infusion-loaded discovery learning model could further improve middle school students’ critical thinking skills than conventional learning.

  16. Development and validation of a piloted simulation of a helicopter and external sling load (United States)

    Shaughnessy, J. D.; Deaux, T. N.; Yenni, K. R.


    A generalized, real time, piloted, visual simulation of a single rotor helicopter, suspension system, and external load is described and validated for the full flight envelope of the U.S. Army CH-54 helicopter and cargo container as an example. The mathematical model described uses modified nonlinear classical rotor theory for both the main rotor and tail rotor, nonlinear fuselage aerodynamics, an elastic suspension system, nonlinear load aerodynamics, and a loadground contact model. The implementation of the mathematical model on a large digital computing system is described, and validation of the simulation is discussed. The mathematical model is validated by comparing measured flight data with simulated data, by comparing linearized system matrices, eigenvalues, and eigenvectors with manufacturers' data, and by the subjective comparison of handling characteristics by experienced pilots. A visual landing display system for use in simulation which generates the pilot's forward looking real world display was examined and a special head up, down looking load/landing zone display is described.

  17. Effect of simulation on the development of critical thinking in associate degree nursing students. (United States)

    Goodstone, Lori; Goodstone, Michael S; Cino, Kathleen; Glaser, Christine A; Kupferman, Kathleen; Dember-Neal, Theresa


    The purpose of this study was to explore the development of critical thinking for students who received instruction using high-fidelity patient simulation (HFPS) versus low-fidelity simulation (instructor-written case studies). Simulated patient care environments have become increasingly more sophisticated in nursing labs, with HFPS fast becoming the standard for laboratory teaching/learning. A convenience sample of first-semester associate degree nursing students participated in this quasi-experimental study. One group of students received weekly HFPS patient simulations and the other group received weekly case studies. Both groups took a pre- and posttest using the Health Studies ReasoningTest. Both groups showed an increase in critical thinking skills; however, there was no statistically significant difference between the HFPS and case study groups. Results suggest that high- and low-fidelity simulations are both associated with increases in critical thinking scores.

  18. Numerical Simulations of Dynamic Behavior of Polyurea Toughened Steel Plates under Impact Loading

    Directory of Open Access Journals (Sweden)

    Chien-Chung Chen


    Full Text Available The objective of the work discussed herein is to develop a nonlinear 3D finite element model to simulate dynamic behavior of polyurea toughened steel plates under impact loading. Experimental and numerical work related to model development are presented. Material properties are incorporated into numerical models to account for strain-rate effects on the dynamic behavior of polyurea and steel. One bare steel plate and four polyurea toughened steel plates were tested under impact loading using a pendulum impact device. Displacement time-history data from experimental work was used to validate the numerical models. Details on material model construction, finite element model development, and model validation are presented and discussed. Results indicate that the developed numerical models can reasonably predict dynamic response of polyurea toughened steel plates under impact loading.

  19. Viscoroute 2.0: a tool for the simulation of moving load effects on asphalt pavement

    CERN Document Server

    Chabot, Armelle; Deloffre, Lydie; Duhamel, Denis


    As shown by strains measured on full scale experimental aircraft structures, traffic of slow-moving multiple loads leads to asymmetric transverse strains that can be higher than longitudinal strains at the bottom of asphalt pavement layers. To analyze this effect, a model and a software called ViscoRoute have been developed. In these tools, the structure is represented by a multilayered half-space, the thermo-viscoelastic behaviour of asphalt layers is accounted by the Huet-Sayegh rheological law and loads are assumed to move at constant speed. First, the paper presents a comparison of results obtained with ViscoRoute to results stemming from the specialized literature. For thick asphalt pavement and several configurations of moving loads, other ViscoRoute simulations confirm that it is necessary to incorporate viscoelastic effects in the modelling to well predict the pavement behaviour and to anticipate possible damages in the structure.

  20. Simulation platform for direct load control of household appliances. Literature survey and G2 implementation

    Energy Technology Data Exchange (ETDEWEB)

    Kolm, J.; Vlaheli, A.


    There is an incentive for the power utilities to look for other ways than building new power stations to satisfy increasing customer power needs. One way to fulfill this demand is by redistributing the available electric power between the different power consumers. This method can successfully be used during high peak hours. The utility is also able to make financial profits selling the redistributed electric power at a higher price to customers with temporary high power demands. Direct Load Control - DLC, a Demand Side Management - DSM tool, is one way to achieve a redistribution of electric power. This masters thesis project consisted in developing a user-friendly simulation platform for domestic appliances combined with an electric power control system to be employed for Direct Load Control. The platform contains the necessary facilities for designing an electrical distribution network model and is implemented in G2, an object-oriented real-time environment. The final application provides an on-line instrument for the utility to control the power consumption over the entire system in terms of dispensing power in an electrical network. The report consists of two main parts. The first part describes a literature survey we systematically compiled to gather literature sources. The second part outlines our design and implementation of the G2 simulation platform for a water-heater model with a Direct Load Control system. The entire simulation platform is designed to allow a flexible change and improvement of the different models. Consequently, our software is a powerful tool for studying a wide range of problems related to a Load Management program involving electrical household loads. 9 refs, 32 figs

  1. Determining Exercise Strength Requirements for Astronaut Critical Mission Tasks: Reaching Under G-Load (United States)

    Schaffner, Grant; Bentley, Jason


    The critical mission tasks assessments effort seeks to determine the physical performance requirements that astronauts must meet in order to safely and successfully accomplish lunar exploration missions. These assessments will determine astronaut preflight strength, fitness, and flexibility requirements, and the extent to which exercise and other countermeasures must prevent the physical deconditioning associated with prolonged weightlessness. The purpose is to determine the flexibility and strength that crewmembers must possess in order to reach Crew Exploration Vehicle controls during maneuvers that result in sustained acceleration levels ranging from 3.7G to 7.8G. An industry standard multibody dynamics application was used to create human models representing a 5th percentile female, a 50th percentile male, and a 95th percentile male. The additional mass of a space suit sleeve was added to the reaching arm to account for the influence of the suit mass on the reaching effort. The human model was merged with computer models of a pilot seat and control panel for the Crew Exploration Vehicle. Three dimensional paths were created that guided the human models hand from a starting position alongside its thigh to three control targets: a joystick, a keyboard, and an overhead switch panel. The reaching motion to each target was repeated under four vehicle acceleration conditions: nominal ascent (3.7G), two ascent aborts (5.5G and 7.8G) and lunar reentry (4.6G). Elbow and shoulder joint angular excursions were analyzed to assess range of motion requirements. Mean and peak elbow and shoulder joint torques were determined and converted to equivalent resistive exercise loads to assess strength requirements. Angular excursions for the 50th and 95th percentile male models remained within joint range of motion limits. For the 5th percentile female, both the elbow and the shoulder exceeded range of motion limits during the overhead reach. Elbow joint torques ranged from 10 N

  2. Improving Care of Critically Unwell Patients through Development of a Simulation Programme in a Malawian Hospital (United States)

    Barnes, Jonathan; Paterson-Brown, Lucy


    Introduction: Malawi is one of the world's poorest countries with very limited healthcare spending and a lack of post-graduate training for healthcare workers, including in critical illness management. Critical illness simulation courses have been shown to be an effective training tool and form a key part of training for healthcare professionals…

  3. Expressions of Critical Thinking in Role-Playing Simulations: Comparisons across Roles (United States)

    Ertmer, Peggy A.; Strobel, Johannes; Cheng, Xi; Chen, Xiaojun; Kim, Hannah; Olesova, Larissa; Sadaf, Ayesha; Tomory, Annette


    The development of critical thinking is crucial in professional education to augment the capabilities of pre-professional students. One method for enhancing critical thinking is participation in role-playing simulation-based scenarios where students work together to resolve a potentially real situation. In this study, undergraduate nursing…

  4. Investigation on pitch system loads by means of an integral multi body simulation approach (United States)

    Berroth, J.; Jacobs, G.; Kroll, T.; Schelenz, R.


    In modern horizontal axis wind turbines the rotor blades are adjusted by three individual pitch systems to control power output. The pitch system consists of either a hydraulic or an electrical actuator, the blade bearing, the rotor blade itself and the control. In case of an electrical drive a gearbox is used to transmit the high torques that are required for blade pitch angle adjustment. In this contribution a new integral multi body simulation approach is presented that enables detailed assessment of dynamic pitch system loads. The simulation results presented are compared and evaluated with measurement data of a 2 MW-class reference wind turbine. Major focus of this contribution is on the assessment of non linear tooth contact behaviour incorporating tooth backlash for the single gear stages and the impact on dynamic pitch system loads.

  5. Numerical simulation of shock absorbers heat load for semi-active vehicle suspension system

    Directory of Open Access Journals (Sweden)

    Demić Miroslav D.


    Full Text Available Dynamic simulation, based on modelling, has a significant role during to the process of vehicle development. It is especially important in the first design stages, when relevant parameters are to be defined. Shock absorber, as an executive part of a semi-active suspension system, is exposed to thermal loads which can lead to its damage and degradation of characteristics. Therefore, this paper attempts to analyze a conversion of mechanical work into heat energy by use of a method of dynamic simulation. The issue of heat dissipation from the shock absorber has not been taken into consideration.

  6. Development of Human Posture Simulation Method for Assessing Posture Angles and Spinal Loads (United States)

    Lu, Ming-Lun; Waters, Thomas; Werren, Dwight


    Video-based posture analysis employing a biomechanical model is gaining a growing popularity for ergonomic assessments. A human posture simulation method of estimating multiple body postural angles and spinal loads from a video record was developed to expedite ergonomic assessments. The method was evaluated by a repeated measures study design with three trunk flexion levels, two lift asymmetry levels, three viewing angles and three trial repetitions as experimental factors. The study comprised two phases evaluating the accuracy of simulating self and other people’s lifting posture via a proxy of a computer-generated humanoid. The mean values of the accuracy of simulating self and humanoid postures were 12° and 15°, respectively. The repeatability of the method for the same lifting condition was excellent (~2°). The least simulation error was associated with side viewing angle. The estimated back compressive force and moment, calculated by a three dimensional biomechanical model, exhibited a range of 5% underestimation. The posture simulation method enables researchers to simultaneously quantify body posture angles and spinal loading variables with accuracy and precision comparable to on-screen posture matching methods. PMID:26361435

  7. Validity of Cognitive Load Measures in Simulation-Based Training: A Systematic Review. (United States)

    Naismith, Laura M; Cavalcanti, Rodrigo B


    Cognitive load theory (CLT) provides a rich framework to inform instructional design. Despite the applicability of CLT to simulation-based medical training, findings from multimedia learning have not been consistently replicated in this context. This lack of transferability may be related to issues in measuring cognitive load (CL) during simulation. The authors conducted a review of CLT studies across simulation training contexts to assess the validity evidence for different CL measures. PRISMA standards were followed. For 48 studies selected from a search of MEDLINE, EMBASE, PsycInfo, CINAHL, and ERIC databases, information was extracted about study aims, methods, validity evidence of measures, and findings. Studies were categorized on the basis of findings and prevalence of validity evidence collected, and statistical comparisons between measurement types and research domains were pursued. CL during simulation training has been measured in diverse populations including medical trainees, pilots, and university students. Most studies (71%; 34) used self-report measures; others included secondary task performance, physiological indices, and observer ratings. Correlations between CL and learning varied from positive to negative. Overall validity evidence for CL measures was low (mean score 1.55/5). Studies reporting greater validity evidence were more likely to report that high CL impaired learning. The authors found evidence that inconsistent correlations between CL and learning may be related to issues of validity in CL measures. Further research would benefit from rigorous documentation of validity and from triangulating measures of CL. This can better inform CLT instructional design for simulation-based medical training.

  8. The Human Operator Simulator. Volume VIII. Applications to Assessment of Operator Loading. (United States)


    N62269-77-C.0109 THE HUMAN OPERATOR SIMULATOR VOLUME Vill,- APPLICATIONS TO ASSESSMENT OF OPERATOR LOADING Floyd A. Glenn Melvin I.’ Strieb Robert Jj...Kristofferson, 1967). Though compelling evidence against this theory of the "psychological moment" has been raised by experiments reported by Allport (1968) and...clearly demonstrated. 31 Is REFERENCES Allport , D.A., Phenomenal simultaneity and the perceptual moment hypo- thesis. British Journal of Psychology

  9. Simulation of Be armour cracking under ITER-like transient heat loads


    Pestchanyi, S.; B. Spilker; Bazylev, B


    Simulation of beryllium cracking under action of multiple severe surface heatings has been performed using the PEGASUS-3D code and verified by experiments in the JUDITH 1 facility. Analysis of the results has revealed beryllium thermo conductivity degradation under action of repetitive pulsed heat load due to accumulation of the cracks in the surface layer. Thermo conductivity degradation is found to be at least 4 times after 100 pulses in JUDITH 1 facility. An analytical model for the Be cra...

  10. Acid deposition and assessment of its critical load for the environmental health of waterbodies in a subtropical watershed, China (United States)

    Jia, Junjie; Gao, Yang


    Atmospheric acidic deposition in subtropical watersheds poses an environmental risk of causing acidification of aquatic ecosystems. In this study, we evaluated the frequency of acid deposition in a subtropical forest ecosystem and the associated critical loads of acidity for a sensitive aquatic ecosystem. We found that out of 132 rainfall events, 33(25%) were acidic rainfall occurrences. Estimated wet acid deposition (2282.78 eq·ha-1·yr-1), consistent with SO42- and NH4+ deposition, was high in spring and summer and low in autumn and winter. Waterbodies surrounded by mixed wood and citrus orchard experience severe acidification, mostly from S deposition because acidic deposition exceeds the corresponding critical loads of acidity. Modifications that take acid rain deposition into consideration are needed for land-use and agricultural management strategies to improve the environmental health of waterbodies in subtropical watersheds.

  11. Tensor RG calculations and quantum simulations near criticality

    CERN Document Server

    Meurice, Y; Tsai, Shan-Wen; Unmuth-Yockey, J; Yang, Li-Ping; Zhang, Jin


    We discuss the reformulation of the O(2) model with a chemical potential and the Abelian Higgs model on a 1+1 dimensional space-time lattice using the Tensor Renormalization Group (TRG) method. The TRG allows exact blocking and connects smoothly the classical Lagrangian approach to the quantum Hamiltonian approach. We calculate the entanglement entropy in the superfluid phase of the O(2) model and show that it approximately obeys the logarithmic Calabrese-Cardy scaling obtained from Conformal Field Theory (CFT). We calculate the Polyakov loop in the Abelian Higgs model and discuss the possibility of a deconfinement transition at finite volume. We propose Bose-Hubbard Hamiltonians implementable on optical lattices as quantum simulators for CFT models.

  12. Searching for Critical Conditions During Lifeboat Launching – Simulations

    Directory of Open Access Journals (Sweden)

    Dymarski Czesław


    Full Text Available The article describes numerical simulations of the process of lifeboat launching at the ship’s side. The research aimed at finding the values of ship motion parameters which appear to be most dangerous for people in the lowered lifeboat due to the generated accelerations. The simplified model of ship hull motion adopted at this research stage bases on a superposition of harmonic motions with given amplitudes and periods in six degrees of freedom. The range of the amplitude of motion for each degree of freedom corresponds approximately to that of possible motion of the PANAMAX type ship on the Baltic sea. In total, 120 960 cases of ship hull motion were examined.

  13. A Universal Educational and Research Stand to Simulate Electrical Drive Loading

    Directory of Open Access Journals (Sweden)

    V. S. Grishin


    Full Text Available Universal educational and research stand was developed for analyzing an electrical drive’s behavior with different load disturbance effects. Major components of the stand are two electrical drives with rigidly coupled shafts. As a result, first electrical drive (loader has a capability to imitate effects of different loading types to another one (trial drive.Control software for the stand is developed. It allows us to combine a variety of loading types and change parameters of current loading such as joint moment, damping, additional inertia, and external torque. Also there is a capability to imitate effects of elasticity and backlash of mechanical transmissions. The paper considers the main challenge of creating the given system, i.e. discretization with a variable step. Some methods to decrease its negative effects on system stability are suggested.The given system allows to change loading parameters more rapidly and in a wider range as compared to a system with real mechanical outfit.These stands are currently used for laboratory classes within the course “Electrical robotic drives” at SM7 department in Bauman Moscow State Technical University. Also the system of interdepended stands for semi-realistic simulation of manipulation systems is under development.

  14. Mission and Safety Critical (MASC) plans for the MASC Kernel simulation (United States)


    This report discusses a prototype for Mission and Safety Critical (MASC) kernel simulation which explains the intended approach and how the simulation will be used. Smalltalk is chosen for the simulation because of usefulness in quickly building working models of the systems and its object-oriented approach to software. A scenario is also introduced to give details about how the simulation works. The eventual system will be a fully object-oriented one implemented in Ada via Dragoon. To implement the simulation, a scenario using elements typical of those in the Space Station, was created.

  15. Continuous separation of protein loaded nanoparticles by simulated moving bed chromatography. (United States)

    Satzer, Peter; Wellhoefer, Martin; Jungbauer, Alois


    For scale up and efficient production of protein loaded nanoparticles continuous separation by size exclusion chromatography in simulated moving bed (SMB) mode helps do reduce unbound protein concentration and increase yields for perfectly covered particles. Silica nanoparticles were loaded with an excess of beta casein or bovine serum albumin (BSA) and the loaded particles purified by size exclusion chromatography using Sephacryl300 as stationary phase in a four zone SMB. We determined our working points for the SMB from batch separations and the triangle theory described by Mazzotti et al. with an SMB setup of one Sephacryl300 26/70mm column per zone with switch times of 5min for BSA and 7min for beta casein. In the case of BSA the Raffinate contained loaded nanoparticles of 63% purity with 98% recovery and the extract was essentially particle free (95% purity). We showed that the low purity of the Raffinate was only due to BSA multimers present in the used protein solution. In the case of beta casein where no multimers are present we achieved 89% purity and 90% recovery of loaded nanoparticles in the Raffinate and an extract free of particles (92% purity). Using a tangential flow filtration unit with 5kDa cutoff membrane we proved that the extract can be concentrated for recycling of protein and buffer. The calculated space-time-yield for loaded nanoparticles was 0.25g of loaded nanoparticles per hour and liter of used resin. This proves that the presented process is suitable for large scale production for industrial purposes. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

  16. Decision-Making in Critical Limb Ischemia: A Markov Simulation. (United States)

    Deutsch, Aaron J; Jain, C Charles; Blumenthal, Kimberly G; Dickinson, Mark W; Neilan, Anne M


    Critical limb ischemia (CLI) is a feared complication of peripheral vascular disease that often requires surgical management and may require amputation of the affected limb. We developed a decision model to inform clinical management for a 63-year-old woman with CLI and multiple medical comorbidities, including advanced heart failure and diabetes. We developed a Markov decision model to evaluate 4 strategies: amputation, surgical bypass, endovascular therapy (e.g. stent or revascularization), and medical management. We measured the impact of parameter uncertainty using 1-way, 2-way, and multiway sensitivity analyses. In the base case, endovascular therapy yielded similar discounted quality-adjusted life months (26.50 QALMs) compared with surgical bypass (26.34 QALMs). Both endovascular and surgical therapies were superior to amputation (18.83 QALMs) and medical management (11.08 QALMs). This finding was robust to a wide range of periprocedural mortality weights and was most sensitive to long-term mortality associated with endovascular and surgical therapies. Utility weights were not stratified by patient comorbidities; nonetheless, our conclusion was robust to a range of utility weight values. For a patient with CLI, endovascular therapy and surgical bypass provided comparable clinical outcomes. However, this finding was sensitive to long-term mortality rates associated with each procedure. Both endovascular and surgical therapies were superior to amputation or medical management in a range of scenarios. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. The use of computers for perioperative simulation in anesthesia, critical care, and pain medicine. (United States)

    Lambden, Simon; Martin, Bruce


    Simulation in perioperative anesthesia training is a field of considerable interest, with an urgent need for tools that reliably train and facilitate objective assessment of performance. This article reviews the available simulation technologies, their evolution, and the current evidence base for their use. The future directions for research in the field and potential applications of simulation technology in anesthesia, critical care, and pain medicine are discussed. Copyright © 2011 Elsevier Inc. All rights reserved.

  18. The Impact of Load Carriage on Measures of Power and Agility in Tactical Occupations: A Critical Review. (United States)

    Joseph, Aaron; Wiley, Amy; Orr, Robin; Schram, Benjamin; Dawes, J Jay


    The current literature suggests that load carriage can impact on a tactical officer's mobility, and that survival in the field may rely on the officer's mobility. The ability for humans to generate power and agility is critical for performance of the high-intensity movements required in the field of duty. The aims of this review were to critically examine the literature investigating the impacts of load carriage on measures of power and agility and to synthesize the findings. The authors completed a search of the literature using key search terms in four databases. After relevant studies were located using strict inclusion and exclusion criteria, the studies were critically appraised using the Downs and Black Checklist and relevant data were extracted and tabled. Fourteen studies were deemed relevant for this review, ranging in percentage quality scores from 42.85% to 71.43%. Outcome measures used in these studies to indicate levels of power and agility included short-distance sprints, vertical jumps, and agility runs, among others. Performance of both power and agility was shown to decrease when tactical load was added to the participants. This suggests that the increase in weight carried by tactical officers may put this population at risk of injury or fatality in the line of duty.

  19. The Impact of Load Carriage on Measures of Power and Agility in Tactical Occupations: A Critical Review

    Directory of Open Access Journals (Sweden)

    Aaron Joseph


    Full Text Available The current literature suggests that load carriage can impact on a tactical officer’s mobility, and that survival in the field may rely on the officer’s mobility. The ability for humans to generate power and agility is critical for performance of the high-intensity movements required in the field of duty. The aims of this review were to critically examine the literature investigating the impacts of load carriage on measures of power and agility and to synthesize the findings. The authors completed a search of the literature using key search terms in four databases. After relevant studies were located using strict inclusion and exclusion criteria, the studies were critically appraised using the Downs and Black Checklist and relevant data were extracted and tabled. Fourteen studies were deemed relevant for this review, ranging in percentage quality scores from 42.85% to 71.43%. Outcome measures used in these studies to indicate levels of power and agility included short-distance sprints, vertical jumps, and agility runs, among others. Performance of both power and agility was shown to decrease when tactical load was added to the participants. This suggests that the increase in weight carried by tactical officers may put this population at risk of injury or fatality in the line of duty.

  20. Cognitive load in distributed and massed practice in virtual reality mastoidectomy simulation. (United States)

    Andersen, Steven Arild Wuyts; Mikkelsen, Peter Trier; Konge, Lars; Cayé-Thomasen, Per; Sørensen, Mads Sølvsten


    Cognitive load theory states that working memory is limited. This has implications for learning and suggests that reducing cognitive load (CL) could promote learning and skills acquisition. This study aims to explore the effect of repeated practice and simulator-integrated tutoring on CL in virtual reality (VR) mastoidectomy simulation. Prospective trial. Forty novice medical students performed 12 repeated virtual mastoidectomy procedures in the Visible Ear Simulator: 21 completed distributed practice with practice blocks spaced in time and 19 participants completed massed practice (all practices performed in 1 day). Participants were randomized for tutoring with the simulator-integrated tutor function. Cognitive load was estimated by measuring reaction time in a secondary task. Data were analyzed using linear mixed models for repeated measurements. The mean reaction time increased by 37% during the procedure compared with baseline, demonstrating that the procedure placed substantial cognitive demands. Repeated practice significantly lowered CL in the distributed practice group but not in massed practice group. In addition, CL was found to be further increased by 10.3% in the later and more complex stages of the procedure. The simulator-integrated tutor function did not have an impact on CL. Distributed practice decreased CL in repeated VR mastoidectomy training more consistently than was seen in massed practice. This suggests a possible effect of skills and memory consolidation occurring over time. To optimize technical skills learning, training should be organized as time-distributed practice rather than as a massed block of practice, which is common in skills-training courses. N/A. © 2015 The American Laryngological, Rhinological and Otological Society, Inc.

  1. Damage in a Distal Radius Fracture Model Treated With Locked Volar Plating After Simulated Postoperative Loading. (United States)

    Salas, Christina; Brantley, Justin A; Clark, James; Taha, Mahmoud Reda; Mercer, Deana M; Myers, Orrin B


    "Damage" is an engineering term defining a period between a state of material perfection and the onset of crack initiation. Clinically, it is a loss of fixation due to microstructural breakdown, indirectly measured as a reduction of stiffness of the bone-implant construct, normalized by the cross-sectional area and length of the bone. The purpose of this study was to characterize damage in a cadaver model of extra-articular distal radius fracture with dorsal comminution treated using 2-column volar distal radius plates. Ten matched distal radii were randomly divided into 2 groups: group I specimens were treated with a volar distal radius plate with an independent, 2-tiered scaffold design; group II specimens (contralateral limbs) were treated with a volar plate with a single-head design for enhanced ulnar buttressing. Specimens were cyclically loaded to simulate a 6-month postoperative load-bearing period. We report damage after a defined protocol of cyclical loading and load to failure simulating a fall on an outstretched hand. Group II specimens experienced more damage under cyclic loading conditions than group I specimens. Group I specimens were stiffer than group II specimens under load-to-failure conditions. Ultimate force at failure in group I and group II specimens was not different. Specimens failed by plate bending (group I, n = 6/10; group II, n = 2/10) and fracture of the lunate facet (group I, n = 4/10; group II, n = 8/10). Group I specimens had less screw cutout at the lunate facet than group II specimens under cyclic loading as indicated by lower damage measures and fewer facet fractures during load-to-failure testing. The overall strength of the construct is not affected by plate design. Microstructural damage or a loss of fixation due to an overly rigid volar plate design may cause malunion or nonunion of fracture fragments and lead to bone-implant instability. Copyright © 2018 American Society for Surgery of the Hand. Published by Elsevier Inc

  2. Cognitive Load in Mastoidectomy Skills Training: Virtual Reality Simulation and Traditional Dissection Compared. (United States)

    Andersen, Steven Arild Wuyts; Mikkelsen, Peter Trier; Konge, Lars; Cayé-Thomasen, Per; Sørensen, Mads Sølvsten


    The cognitive load (CL) theoretical framework suggests that working memory is limited, which has implications for learning and skills acquisition. Complex learning situations such as surgical skills training can potentially induce a cognitive overload, inhibiting learning. This study aims to compare CL in traditional cadaveric dissection training and virtual reality (VR) simulation training of mastoidectomy. A prospective, crossover study. Participants performed cadaveric dissection before VR simulation of the procedure or vice versa. CL was estimated by secondary-task reaction time testing at baseline and during the procedure in both training modalities. The national Danish temporal bone course. A total of 40 novice otorhinolaryngology residents. Reaction time was increased by 20% in VR simulation training and 55% in cadaveric dissection training of mastoidectomy compared with baseline measurements. Traditional dissection training increased CL significantly more than VR simulation training (p < 0.001). VR simulation training imposed a lower CL than traditional cadaveric dissection training of mastoidectomy. Learning complex surgical skills can be a challenge for the novice and mastoidectomy skills training could potentially be optimized by employing VR simulation training first because of the lower CL. Traditional dissection training could then be used to supplement skills training after basic competencies have been acquired in the VR simulation. Copyright © 2015 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

  3. Effect of simulation on nursing knowledge and critical thinking in failure to rescue events. (United States)

    Schubert, Carolyn R


    Failure to rescue events are hospital deaths that result from human error and unsafe patient conditions. A failure to rescue event implies that the last and best chance to avoid tragedy is not acted on in time to avoid a disaster. Patient safety is often compromised by nurses who do not perform accurate assessments (vigilance), do not detect clinical changes (surveillance), or do not display critical thinking (recognition that something is wrong). This project used simulation as a teaching strategy to enhance nursing performance. Medical-surgical nurses took part in a simulated failure to rescue event in which the patient's clinical condition deteriorated rapidly. Nursing knowledge and critical thinking improved after the simulation and showed the effectiveness of simulation as a teaching strategy to address nursing knowledge and critical thinking skills. Copyright 2012, SLACK Incorporated.

  4. Reproducibility of the Internal Load and Performance-Based Responses to Simulated Amateur Boxing. (United States)

    Thomson, Edward D; Lamb, Kevin L


    Thomson, ED and Lamb, KL. Reproducibility of the internal load and performance-based responses to simulated amateur boxing. J Strength Cond Res 31(12): 3396-3402, 2017-The aim of this study was to examine the reproducibility of the internal load and performance-based responses to repeated bouts of a three-round amateur boxing simulation protocol (boxing conditioning and fitness test [BOXFIT]). Twenty-eight amateur boxers completed 2 familiarization trials before performing 2 complete trials of the BOXFIT, separated by 4-7 days. To characterize the internal load, mean (HRmean) and peak (HRpeak) heart rate, breath-by-breath oxygen uptake (V[Combining Dot Above]O2), aerobic energy expenditure, excess carbon dioxide production (CO2excess), and ratings of perceived exertion were recorded throughout each round, and blood lactate determined post-BOXFIT. Additionally, an indication of the performance-based demands of the BOXFIT was provided by a measure of acceleration of the punches thrown in each round. Analyses revealed there were no significant differences (p > 0.05) between repeated trials in any round for all dependent measures. The typical error (coefficient variation %) for all but 1 marker of internal load (CO2excess) was 1.2-16.5% and reflected a consistency that was sufficient for the detection of moderate changes in variables owing to an intervention. The reproducibility of the punch accelerations was high (coefficient of variance % range = 2.1-2.7%). In general, these findings suggest that the internal load and performance-based efforts recorded during the BOXFIT are reproducible and, thereby, offer practitioners a method by which meaningful changes impacting on performance could be identified.

  5. Dynamic load synthesis for shock numerical simulation in space structure design (United States)

    Monti, Riccardo; Gasbarri, Paolo


    Pyroshock loads are the most stressing environments that a space equipment experiences during its operating life from a mechanical point of view. In general, the mechanical designer considers the pyroshock analysis as a very demanding constraint. Unfortunately, due to the non-linear behaviour of the structure under such loads, only the experimental tests can demonstrate if it is able to withstand these dynamic loads. By taking all the previous considerations into account, some preliminary information about the design correctness could be done by performing ;ad-hoc; numerical simulations, for example via commercial finite element software (i.e. MSC Nastran). Usually these numerical tools face the shock solution in two ways: 1) a direct mode, by using a time dependent enforcement and by evaluating the time-response and space-response as well as the internal forces; 2) a modal basis approach, by considering a frequency dependent load and of course by evaluating internal forces in the frequency domain. This paper has the main aim to develop a numerical tool to synthetize the time dependent enforcement based on deterministic and/or genetic algorithm optimisers. In particular starting from a specified spectrum in terms of SRS (Shock Response Spectrum) a time dependent discrete function, typically an acceleration profile, will be obtained to force the equipment by simulating the shock event. The synthetizing time and the interface with standards numerical codes will be two of the main topics dealt with in the paper. In addition a congruity and consistency methodology will be presented to ensure that the identified time dependent loads fully match the specified spectrum.

  6. Insights and issues with simulating terrestrial DOC loading of Arctic river networks (United States)

    Kicklighter, David W.; Hayes, Daniel J.; McClelland, James W.; Peterson, Bruce J.; McGuire, A. David; Melillo, Jerry M.


    Terrestrial carbon dynamics influence the contribution of dissolved organic carbon (DOC) to river networks in addition to hydrology. In this study, we use a biogeochemical process model to simulate the lateral transfer of DOC from land to the Arctic Ocean via riverine transport. We estimate that, over the 20th century, the pan-Arctic watershed has contributed, on average, 32 Tg C/yr of DOC to river networks emptying into the Arctic Ocean with most of the DOC coming from the extensive area of boreal deciduous needle-leaved forests and forested wetlands in Eurasian watersheds. We also estimate that the rate of terrestrial DOC loading has been increasing by 0.037 Tg C/yr2 over the 20th century primarily as a result of climate-induced increases in water yield. These increases have been offset by decreases in terrestrial DOC loading caused by wildfires. Other environmental factors (CO2 fertilization, ozone pollution, atmospheric nitrogen deposition, timber harvest, agriculture) are estimated to have relatively small effects on terrestrial DOC loading to Arctic rivers. The effects of the various environmental factors on terrestrial carbon dynamics have both offset and enhanced concurrent effects on hydrology to influence terrestrial DOC loading and may be changing the relative importance of terrestrial carbon dynamics on this carbon flux. Improvements in simulating terrestrial DOC loading to pan-Arctic rivers in the future will require better information on the production and consumption of DOC within the soil profile, the transfer of DOC from land to headwater streams, the spatial distribution of precipitation and its temporal trends, carbon dynamics of larch-dominated ecosystems in eastern Siberia, and the role of industrial organic effluents on carbon budgets of rivers in western Russia.

  7. Wettability alteration properties of fluorinated silica nanoparticles in liquid-loaded pores: An atomistic simulation

    Energy Technology Data Exchange (ETDEWEB)

    Sepehrinia, Kazem; Mohammadi, Aliasghar, E-mail:


    Highlights: • Properties of fluorinated silica nanoparticles were investigated in water or decane-loaded pores of mineral silica using molecular dynamics simulation. • The water or decane-loaded pores represent liquid bridging. • Addition of nanoparticles to liquid-loaded pores results in weakening of the liquid bridge. • The hydrophobicity of the pore wall increases in the presence of adsorbed fluorinated silica nanoparticles. - Abstract: Control over the wettability of reservoir rocks is of crucial importance for enhancing oil and gas recovery. In order to develop chemicals for controlling the wettability of reservoir rocks, we present a study of functionalized silica nanoparticles as candidates for wettability alteration and improved gas recovery applications. In this paper, properties of fluorinated silica nanoparticles were investigated in water or decane-loaded pores of mineral silica using molecular dynamics simulation. Trifluoromethyl groups as water and oil repellents were placed on the nanoparticles. Simulating a pore in the presence of trapped water or decane molecules leads to liquid bridging for both of the liquids. Adsorption of nanoparticles on the pore wall reduces the density of liquid molecules adjacent to the wall. The density of liquid molecules around the nanoparticles decreases significantly with increasing the number of trifluoromethyl groups on the nanoparticles’ surfaces. An increased hydrophobicity of the pore wall was observed in the presence of adsorbed fluorinated silica nanoparticles. Also, it is observed that increasing the number of the trifluoromethyl groups results in weakening of liquid bridges. Moreover, the free energy of adsorption on mineral surface was evaluated to be more favorable than that of aggregation of nanoparticles, which suggests nanoparticles adsorb preferably on mineral surface.

  8. Simulation of Distance Relay for Load Encroachment Alleviation with Agent Based Supervision of Zone3

    Directory of Open Access Journals (Sweden)

    Mohamed Badr


    Full Text Available Cascaded tripping of power lines due to mal-operation of zone-3 distance relays has been one of the main causes of many previous blackouts worldwide. Encroachment of load into zone-3 characteristics during stressed system operation conditions is a basic factor for such mal-operation of the relays. By improving the operation of zone-3, it is possible to prevent mal-operations so that cascaded line tripping can be avoided. For proper study of the behavior of distance relay during faults and load encroachment phenomenon, we must build a model of distance relay, so in this paper a modeling study of distance relay is implemented using MATLAB/Simulink program. However, this model is distinguished from previous models that, examines in detail the third zone of distance relay. Many cases are simulated with changing line loading and fault location to ensure the capability of the relay to detect the fault and thus the maximum load ability limit of distance relay is obtained. In order to prevent cascading events caused by hidden failures in zone-3 relays, agent based relay architectures have been suggested in the recent past. In such architectures each zone-3 relay contains agents that require communication with other agents at various relevant relays in order to distinguish a real zone-3 event from a temporary overload. In this paper, a local master agent is consulted by all zone-3 agents before a tripping decision is made. The master agent maintains a rule base which is updated based on the local topology of the network and real time monitoring of the status of other relays and circuit breakers. Cisco Packet Tracer program is used for running communication network simulations. The result of the simulation indicate that the time estimated to send and receive a packet data unit (PDU message between one relay to anther can satisfy the communication requirement for the proposed scheme with fiber media.

  9. Critical mechanical properties and FEA simulation for crashworthiness assessment of a coarse-grained cast AM50 alloy

    Directory of Open Access Journals (Sweden)

    S. Xu


    Full Text Available A coarse-grained AM50 alloy was used as a model alloy for investigation of constitutive behaviour, Charpy toughness and effect of stress state on deformation and failure of cast Mg alloys. The results provide critical mechanical properties of a cast AM50 alloy for crashworthiness assessment and development of finite element simulation techniques. For cast Mg alloys, the effect of strain rate and temperature is larger on tensile strength than on compressive strength because twinning is more extensive in compression than in tension. The effect of strain rate on compressive strength is negligible because twinning activity of the cast Mg alloy is dominant. The load vs. deflection of Charpy specimens were measured for modelling, and the effect of loading rate and temperature on load of Charpy specimens is very small because part of the specimen is in compression. The equivalent strain to fracture of the cylindrical round notched tension specimen decreases with increasing stress triaxiality; though for the flat-grooved plane strain specimen, the equivalent fracture strain remains constant over the range of stress triaxiality investigated. Because the two different specimen geometries give rise to different Lode angle values, the test results show that the Lode angle parameter is an important parameter for deformation and fracture of Mg alloys. Finite element simulations of loading of the cylindrical notched-tension and Charpy specimens were carried out using a Lode-angle dependent von Mises model, and were found to provide a reasonable description of the load–displacement curves measured in the tests. For the flat-grooved plane strain specimens, the computations under-predicted the force–displacement response measured.

  10. Novel models and algorithms of load balancing for variable-structured collaborative simulation under HLA/RTI (United States)

    Yue, Yingchao; Fan, Wenhui; Xiao, Tianyuan; Ma, Cheng


    High level architecture(HLA) is the open standard in the collaborative simulation field. Scholars have been paying close attention to theoretical research on and engineering applications of collaborative simulation based on HLA/RTI, which extends HLA in various aspects like functionality and efficiency. However, related study on the load balancing problem of HLA collaborative simulation is insufficient. Without load balancing, collaborative simulation under HLA/RTI may encounter performance reduction or even fatal errors. In this paper, load balancing is further divided into static problems and dynamic problems. A multi-objective model is established and the randomness of model parameters is taken into consideration for static load balancing, which makes the model more credible. The Monte Carlo based optimization algorithm(MCOA) is excogitated to gain static load balance. For dynamic load balancing, a new type of dynamic load balancing problem is put forward with regards to the variable-structured collaborative simulation under HLA/RTI. In order to minimize the influence against the running collaborative simulation, the ordinal optimization based algorithm(OOA) is devised to shorten the optimization time. Furthermore, the two algorithms are adopted in simulation experiments of different scenarios, which demonstrate their effectiveness and efficiency. An engineering experiment about collaborative simulation under HLA/RTI of high speed electricity multiple units(EMU) is also conducted to indentify credibility of the proposed models and supportive utility of MCOA and OOA to practical engineering systems. The proposed research ensures compatibility of traditional HLA, enhances the ability for assigning simulation loads onto computing units both statically and dynamically, improves the performance of collaborative simulation system and makes full use of the hardware resources.

  11. Numerical Simulation of Interactions between Corrosion Pits on Stainless Steel under Loading Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Haitao; Han, En-Hou [Chinese Academy of Sciences, Shenyang (China)


    The interactions between corrosion pits on stainless steel under loading conditions are studied by using a cellular automata model coupled with finite element method at a mesoscopic scale. The cellular automata model focuses on a metal/film/electrolyte system, including anodic dissolution, passivation, diffusion of hydrogen ions and salt film hydrolysis. The Chopard block algorithm is used to improve the diffusion simulation efficiency. The finite element method is used to calculate the stress concentration on the pit surface during pit growth, and the effect of local stress and strain on anodic current is obtained by using the Gutman model, which is used as the boundary conditions of the cellular automata model. The transient current characteristics of the interactions between corrosion pits under different simulation factors including the breakdown of the passive film at the pit mouth and the diffusion of hydrogen ions are analyzed. The analysis of the pit stability product shows that the simulation results are close to the experimental conclusions.

  12. Vertical accelerator device to apply loads simulating blast environments in the military to human surrogates. (United States)

    Yoganandan, Narayan; Pintar, Frank A; Schlick, Michael; Humm, John R; Voo, Liming; Merkle, Andrew; Kleinberger, Michael


    The objective of the study was to develop a simple device, Vertical accelerator (Vertac), to apply vertical impact loads to Post Mortem Human Subject (PMHS) or dummy surrogates because injuries sustained in military conflicts are associated with this vector; example, under-body blasts from explosive devices/events. The two-part mechanically controlled device consisted of load-application and load-receiving sections connected by a lever arm. The former section incorporated a falling weight to impact one end of the lever arm inducing a reaction at the other/load-receiving end. The "launch-plate" on this end of the arm applied the vertical impact load/acceleration pulse under different initial conditions to biological/physical surrogates, attached to second section. It is possible to induce different acceleration pulses by using varying energy absorbing materials and controlling drop height and weight. The second section of Vertac had the flexibility to accommodate different body regions for vertical loading experiments. The device is simple and inexpensive. It has the ability to control pulses and flexibility to accommodate different sub-systems/components of human surrogates. It has the capability to incorporate preloads and military personal protective equipment (e.g., combat helmet). It can simulate vehicle roofs. The device allows for intermittent specimen evaluations (x-ray and palpation, without changing specimen alignment). The two free but interconnected sections can be used to advance safety to military personnel. Examples demonstrating feasibilities of the Vertac device to apply vertical impact accelerations using PMHS head-neck preparations with helmet and booted Hybrid III dummy lower leg preparations under in-contact and launch-type impact experiments are presented. Published by Elsevier Ltd.

  13. Spatial variation of atmospheric nitrogen deposition and critical loads for aquatic ecosystems in the Greater Yellowstone Area. (United States)

    Nanus, L; McMurray, J A; Clow, D W; Saros, J E; Blett, T; Gurdak, J J


    Current and historic atmospheric nitrogen (N) deposition has impacted aquatic ecosystems in the Greater Yellowstone Area (GYA). Understanding the spatial variation in total atmospheric deposition (wet + dry) of N is needed to estimate air pollution deposition critical loads for sensitive aquatic ecosystems. This is particularly important for areas that have an increasing contribution of ammonia dry deposition to total N (TN), such as the GYA. High resolution geostatistical models and maps of TN deposition (wet + dry) were developed using a variety of techniques including ordinary kriging in a geographic information system, to evaluate spatial variability and identify areas of elevated loading of pollutants for the GYA. TN deposition estimates in the GYA range from <1.4 to 7.5 kg N ha-1 yr-1 and show greater variability than wet inorganic N deposition. Critical loads of TN deposition (CLTNdep) for nutrient enrichment in aquatic ecosystems range from less than 1.5 ± 1.0 kg N ha-1 yr-1 to over 4.0 ± 1.0 kg N ha-1 yr-1 and variability is controlled by differences in basin characteristics. The lowest CLTNdep estimates occurred in high elevation basins within GYA Wilderness boundaries. TN deposition maps were used to identify critical load exceedances for aquatic ecosystems. Estimated CLTNdep exceedances for the GYA range from 17% to 48% depending on the surface water nitrate (NO3-) threshold. Based on a NO3- threshold of 1.0 μmol L-1, TN deposition exceeds CLTNdep in approximately 30% of the GYA. These predictive models and maps can be used to help identify and protect sensitive ecosystems that may be impacted by excess atmospheric N deposition. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Simulation of Complex Cracking in Plain Weave C/SiC Composite under Biaxial Loading (United States)

    Cheng, Ron-Bin; Hsu, Su-Yuen


    Finite element analysis is performed on a mesh, based on computed geometry of a plain weave C/SiC composite with assumed internal stacking, to reveal the pattern of internal damage due to biaxial normal cyclic loading. The simulation encompasses intertow matrix cracking, matrix cracking inside the tows, and separation at the tow-intertow matrix and tow-tow interfaces. All these dissipative behaviors are represented by traction-separation cohesive laws. Not aimed at quantitatively predicting the overall stress-strain relation, the simulation, however, does not take the actual process of fiber debonding into account. The fiber tows are represented by a simple rule-of-mixture model where the reinforcing phase is a hypothetical one-dimensional material. Numerical results indicate that for the plain weave C/SiC composite, 1) matrix-crack initiation sites are primarily determined by large intertow matrix voids and interlayer tow-tow contacts, 2) the pattern of internal damage strongly depends on the loading path and initial stress, 3) compressive loading inflicts virtually no damage evolution. KEY WORDS: ceramic matrix composite, plain weave, cohesive model, brittle failure, smeared crack model, progressive damage, meso-mechanical analysis, finite element.

  15. Simulation of Propellant Loading System Senior Design Implement in Computer Algorithm (United States)

    Bandyopadhyay, Alak


    Propellant loading from the Storage Tank to the External Tank is one of the very important and time consuming pre-launch ground operations for the launch vehicle. The propellant loading system is a complex integrated system involving many physical components such as the storage tank filled with cryogenic fluid at a very low temperature, the long pipe line connecting the storage tank with the external tank, the external tank along with the flare stack, and vent systems for releasing the excess fuel. Some of the very important parameters useful for design purpose are the prediction of pre-chill time, loading time, amount of fuel lost, the maximum pressure rise etc. The physics involved for mathematical modeling is quite complex due to the fact the process is unsteady, there is phase change as some of the fuel changes from liquid to gas state, then conjugate heat transfer in the pipe walls as well as between solid-to-fluid region. The simulation is very tedious and time consuming too. So overall, this is a complex system and the objective of the work is student's involvement and work in the parametric study and optimization of numerical modeling towards the design of such system. The students have to first become familiar and understand the physical process, the related mathematics and the numerical algorithm. The work involves exploring (i) improved algorithm to make the transient simulation computationally effective (reduced CPU time) and (ii) Parametric study to evaluate design parameters by changing the operational conditions

  16. Simulation de postes de chargement en mer Simulation of Offshore Loading Stations

    Directory of Open Access Journals (Sweden)

    Plaut D.


    Full Text Available L'importance que revêt, pour l'industrie pétrolière, le choix des investissements de développement d'un champ en mer a amené à construire un modèle de simulation afin de fournir une aide à la décision. Ce modèle dont le champ d'application a été rendu aussi large que possible a fait l'objet d'une thèse. Il se traduit en un programme informatique dont les temps de calcul très réduits permettent une approche pas à pas de la solution optimale. The importance for the petroleum industry of choosing development investments for an offshore field has led to the construction of a simulation model to provide help with decision making. A thesis has been written about this model whose range of application has been made as broad as possible. The result is a computer program having greatly reduced computing time for a step-by-step approach to the optimum solution.

  17. Propagation of hydrological modeling uncertainties on bed load transport simulations in steep mountain streams (United States)

    Eichner, Bernhard; Koller, Julian; Kammerlander, Johannes; Schöber, Johannes; Achleitner, Stefan


    As mountain streams are sources of both, water and sediment, they are strongly influencing the whole downstream river network. Besides large flood flow events, the continuous transport of sediments during the year is in the focus of this work. Since small mountain streams are usually not measured, spatial distributed hydrological models are used to assess the internal discharges triggering the sediment transport. In general model calibration will never be perfect and is focused on specific criteria such as mass balance or peak flow, etc. The remaining uncertainties influence the subsequent applications, where the simulation results are used. The presented work focuses on the question, how modelling uncertainties in hydrological modelling impact the subsequent simulation of sediment transport. The applied auto calibration by means of MonteCarlo Simulation optimizes the model parameters for different aspects (efficiency criteria) of the runoff time series. In this case, we investigated the impacts of different hydrological criteria on a subsequent bed load transport simulation in catchment of the Längentaler Bach, a small catchment in the Stubai Alps. The used hydrologic model HQSim is a physically based semi-distributed water balance model. Different hydrologic response units (HRU), which are characterized by elevation, orientation, vegetation, soil type and depth, drain with various delay into specified river reaches. The runoff results of the Monte-Carlo simulation are evaluated in comparison to runoff gauge, where water is collected by the Tiroler Wasserkraft AG (TIWAG). Using the Nash-Sutcliffe efficiency (NSE) on events and main runoff period (summer), the weighted root mean squared error (RMSE) on duration curve and a combination of different criteria, a set of best fit parametrization with varying runoff series was received as input for the bed load transport simulation. These simulations are performed with sedFlow, a tool especially developed for bed load

  18. Neurology Education for Critical Care Fellows Using High-Fidelity Simulation. (United States)

    Braksick, Sherri A; Kashani, Kianoush; Hocker, Sara


    Simulation is becoming a more common modality in medical education. The data regarding effectiveness of simulation in critical care neurology education are limited. We administered a three-scenario simulation course to critical care fellowship trainees at a large academic medical center as a part of their core curriculum requirement. Pre- and posttests assessing medical knowledge and trainee confidence in managing neurologic disease were completed by all trainees. Overall satisfaction and effectiveness were evaluated following the course. Change in trainee knowledge and confidence before and after the course was assessed for improvement. Sixteen trainees completed the simulation course. Prior to completion, medical knowledge was 5.2 ± 0.9 (of 8 possible correct answers) and following the course was 6.4 ± 1.3 (p = 0.002). Overall confidence improved from 15.4 ± 4.9 (of 30 possible points) to 20.7 ± 3.3 (p = Simulation is an effective means of neurologic education for critical care trainees, with improvement in both medical knowledge and trainee confidence after completion of a three-scenario simulation experience. This course ensures the exposure of critical care trainees to neurologic diseases that are required curricular milestones to successfully complete the fellowship training program.

  19. The Effect of Learning Styles, Critical Thinking Disposition, and Critical Thinking on Clinical Judgment in Senior Baccalaureate Nursing Students during Human Patient Simulation (United States)

    McCormick, Kiyan


    Simulated learning experiences using high-fidelity human patient simulators (HPS) are increasingly being integrated into baccalaureate nursing programs. Thus, the purpose of this study was to examine relationships among learning style, critical thinking disposition, critical thinking, and clinical judgment during high-fidelity human patient…

  20. Comparison of road load simulator test results with track tests on electric vehicle propulsion system (United States)

    Dustin, M. O.


    A special-purpose dynamometer, the road load simulator (RLS), is being used at NASA's Lewis Research Center to test and evaluate electric vehicle propulsion systems developed under DOE's Electric and Hybrid Vehicle Program. To improve correlation between system tests on the RLS and track tests, similar tests were conducted on the same propulsion system on the RLS and on a test track. These tests are compared in this report. Battery current to maintain a constant vehicle speed with a fixed throttle was used for the comparison. Scatter in the data was greater in the track test results. This is attributable to variations in tire rolling resistance and wind effects in the track data. It also appeared that the RLS road load, determined by coastdown tests on the track, was lower than that of the vehicle on the track. These differences may be due to differences in tire temperature.

  1. Musculoskeletal simulations to investigate the influence of vertebral geometrical parameters on lumbar spine loading

    DEFF Research Database (Denmark)

    Putzer, Michael; Rasmussen, John; Penzkofer, Rainer

    Musculoskeletal simulations of subject-specific loads in the lumbar spine are computed by using subject-specific geometrical data. However this data has an inherent inaccuracy. This study evaluates the influence of defined geometrical parameters on lumbar spine loading utilizing the Any......Body Modeling System and a parameterized musculoskeletal lumbar spine model for four different postures: upright standing, flexion (50°), torsion (10°) and lateral bending (15°). The linear dimensions of the vertebral body, the posterior parts of the vertebrae as well as the disc height, the orientation...... of the facet joints and the curvature of the lumbar spine have been varied. Figure 1 depicts the used musculoskeletal model in the flexed posture and a lumbar vertebra labeled with all relevant linear dimensions except the disc height. Additionally, all combinations of the three parameters vertebral body...

  2. Numerical Simulation of Rock Fragmentation under the Impact Load of Water Jet

    Directory of Open Access Journals (Sweden)

    Jiang Hongxiang


    Full Text Available To investigate the rock fragmentation and its influence factors under the impact load of water jet, a numerical method which coupled finite element method (FEM with smoothed particle hydrodynamics (SPH was adopted to simulate the rock fragmentation process by water jet. Linear and shock equations of state were applied to describe the dynamic characteristics of rock and water, respectively, while the maximum principal stress criterion was used for the rock failure detection. The dynamic stresses at the selected element containing points in rock are computed as a function of time under the impact load of water jet. The influences of the factors of boundary condition, impact velocity, confining pressure, and structure plane on rock dynamic fragmentation are discussed.

  3. Damage Simulation in Non-Crimp Fabric Composite Plates Subjected to Impact Loads (United States)

    Satyanarayana, Arunkumar; Bogert, Philip B.; Aitharaju, Venkat; Aashat, Satvir; Kia, Hamid


    Progressive failure analysis (PFA) of non-crimp fabric (NCF) composite laminates subjected to low velocity impact loads was performed using the COmplete STress Reduction (COSTR) damage model implemented through VUMAT and UMAT41 user subroutines in the frame works of the commercial finite element programs ABAQUS/Explicit and LS-DYNA, respectively. To validate the model, low velocity experiments were conducted and detailed correlations between the predictions and measurements for both intra-laminar and inter-laminar failures were made. The developed material and damage model predicts the peak impact load and duration very close with the experimental results. Also, the simulation results of delamination damage between the ply interfaces, in-plane matrix damages and fiber damages were all in good agreement with the measurements from the non-destructive evaluation data.

  4. High-fidelity simulations of blast loadings in urban environments using an overset meshing strategy (United States)

    Wang, X.; Remotigue, M.; Arnoldus, Q.; Janus, M.; Luke, E.; Thompson, D.; Weed, R.; Bessette, G.


    Detailed blast propagation and evolution through multiple structures representing an urban environment were simulated using the code Loci/BLAST, which employs an overset meshing strategy. The use of overset meshes simplifies mesh generation by allowing meshes for individual component geometries to be generated independently. Detailed blast propagation and evolution through multiple structures, wave reflection and interaction between structures, and blast loadings on structures were simulated and analyzed. Predicted results showed good agreement with experimental data generated by the US Army Engineer Research and Development Center. Loci/BLAST results were also found to compare favorably to simulations obtained using the Second-Order Hydrodynamic Automatic Mesh Refinement Code (SHAMRC). The results obtained demonstrated that blast reflections in an urban setting significantly increased the blast loads on adjacent buildings. Correlations of computational results with experimental data yielded valuable insights into the physics of blast propagation, reflection, and interaction under an urban setting and verified the use of Loci/BLAST as a viable tool for urban blast analysis.

  5. Numerical simulation of stress field for laser thermal loading on piston (United States)

    Liu, Xiu-Bo; Pang, Ming; Zhang, Zhen-Guo; Tan, Jian-Song; Zhu, Gang-Xian; Wang, Ming-Di


    To investigate the laser thermal loading on diesel engine piston, the employed Gaussian laser beam was transformed into concentric multi-circular patterns of specific intensity distributions with the aid of diffractive optical elements (DOEs), the time duration of laser thermal loading was controlled by computer with air cooling on the top surface of piston, and water cooling of oil tunnel and bottom surface of piston. Numerical simulation model of stress field of laser thermal action was established with the consideration of experimental conditions and the temperature dependent of thermal physical properties of the piston materials. Results show that the stress fluctuation rate at the concave pit site of top surface of piston is larger than that of laser irradiated region due to concave pit region near oil tunnel. Meanwhile, the regions of concave pit, oil tunnel and inner chamber near the top surface of piston are most vulnerable sites to form thermal cracks due to their direct contact with the cooling medium. Results of experimental and numerical simulation have good agreement, which validates the numerical simulation mode.

  6. Measuring Cognitive Load during Simulation-Based Psychomotor Skills Training: Sensitivity of Secondary-Task Performance and Subjective Ratings (United States)

    Haji, Faizal A.; Khan, Rabia; Regehr, Glenn; Drake, James; de Ribaupierre, Sandrine; Dubrowski, Adam


    As interest in applying cognitive load theory (CLT) to the study and design of pedagogic and technological approaches in healthcare simulation grows, suitable measures of cognitive load (CL) are needed. Here, we report a two-phased study investigating the sensitivity of subjective ratings of mental effort (SRME) and secondary-task performance…

  7. Assessment of Critical Loads Instigating Voltage Instability in Transmission Network using Novel Load Tracing Capable Index LQP_LT and PSS/E Tools Validation

    Directory of Open Access Journals (Sweden)

    Renuga Verayiah


    Full Text Available Existing power systems are significantly susceptible to voltage instability problem since such systems are stressed with the huge power transfers across the grids. Various power tracing techniques have been developed but are limited to the application of transmission service pricing in a deregulated environment. This paper presents a novel approach which adopts the power tracing theory for voltage stability improvement via the development of reactive power tracing capable index, named as LQP_LT. The index is tested in IEEE 14 Test Bus System in various contingency states and comparison were made using the results obtained from the industrial graded software PSS/E in evaluating the critical transmission lines in severe contingencies. The LQP_LT index is found to be effective in determining the weak load buses in a transmission system which ultimately responsible to cause stressed lines and overall voltage instability in a system.

  8. Assessing Critical Thinking Outcomes of Dental Hygiene Students Utilizing Virtual Patient Simulation: A Mixed Methods Study. (United States)

    Allaire, Joanna L


    Dental hygiene educators must determine which educational practices best promote critical thinking, a quality necessary to translate knowledge into sound clinical decision making. The aim of this small pilot study was to determine whether virtual patient simulation had an effect on the critical thinking of dental hygiene students. A pretest-posttest design using the Health Science Reasoning Test was used to evaluate the critical thinking skills of senior dental hygiene students at The University of Texas School of Dentistry at Houston Dental Hygiene Program before and after their experience with computer-based patient simulation cases. Additional survey questions sought to identify the students' perceptions of whether the experience had helped develop their critical thinking skills and improved their ability to provide competent patient care. A convenience sample of 31 senior dental hygiene students completed both the pretest and posttest (81.5% of total students in that class); 30 senior dental hygiene students completed the survey on perceptions of the simulation (78.9% response rate). Although the results did not show a significant increase in mean scores, the students reported feeling that the use of virtual patients was an effective teaching method to promote critical thinking, problem-solving, and confidence in the clinical realm. The results of this pilot study may have implications to support the use of virtual patient simulations in dental hygiene education. Future research could include a larger controlled study to validate findings from this study.

  9. Progressive Damage Simulation of Laminates in Wind Turbine Blades under Quasistatic and Cyclic Loading.


    Bak, Brian Lau Verndal


    The overall purpose of this Ph.D. project has been to develop a framework of methods for progressive delamination modeling and simulation of composite laminates in large scale structures under both quasi-static and fatigue loading.The first part of the thesis is an introduction to the project and provides a short introduction to selected basic topics of the theoretical background of the work presented in the papers.The second part of the thesis consists of three refereed journal papers.Paper ...

  10. Simulation of Be armour cracking under ITER-like transient heat loads

    Directory of Open Access Journals (Sweden)

    S. Pestchanyi


    Full Text Available Simulation of beryllium cracking under action of multiple severe surface heatings has been performed using the PEGASUS-3D code and verified by experiments in the JUDITH 1 facility. Analysis of the results has revealed beryllium thermo conductivity degradation under action of repetitive pulsed heat load due to accumulation of the cracks in the surface layer. Thermo conductivity degradation is found to be at least 4 times after 100 pulses in JUDITH 1 facility. An analytical model for the Be cracking threshold under action of arbitrary heat pulses has been developed.

  11. Loading and testing a light scattering cell with a binary fluid mixture near its critical composition (United States)

    Jacobs, Donald T.; Becker, James S.


    Critical phenomena has been the subject of physics research for many years. However, only in recent years has the research effort become intense. The current intensity has caused the study of critical phenomena to be grouped into a previous older era and a present contemporary era. Turbidity cell filling with methanol cyclohexane is one of the first steps toward a further understanding of critical phenomena. Work performed during the research period is outlined. During this period, research was spent developing apparatus and techniques that will make it possible to study critical phenomena through turbidity measurements on methanol cyclohexane. Topics covered range from the orientation of turbidity cell parts for assembly to the filling apparatus and procedure used when th cell is built. The last section will briefly cover some of the observations made when viewing the cell in a controlled water bath. However, before mention is made of the specifics of the summer research, a short introduction to critical phenomena and turbidity and how they relate to this experiment is provided.

  12. The effect of human patient simulation on critical thinking and its predictors in prelicensure nursing students. (United States)

    Shinnick, Mary Ann; Woo, Mary A


    Human patient simulation (HPS) is becoming a popular teaching method in nursing education globally and is believed to enhance both knowledge and critical thinking. While there is evidence that HPS improves knowledge, there is no objective nursing data to support HPS impact on critical thinking. Therefore, we studied knowledge and critical thinking before and after HPS in prelicensure nursing students and attempted to identify the predictors of higher critical thinking scores. Using a one-group, quasi-experimental, pre-test post-test design, 154 prelicensure nursing students (age 25.7± 6.7; gender=87.7% female) from 3 schools were studied at the same point in their curriculum using a high-fidelity simulation. Pre- and post-HPS assessments of knowledge, critical thinking, and self-efficacy were done as well as assessments for demographics and learning style. There was a mean improvement in knowledge scores of 6.5 points (Pcritical thinking scores. A logistic regression with 10 covariates revealed three variables to be predictors of higher critical thinking scores: greater "age" (P=0.01), baseline "knowledge" (P=0.04) and a low self-efficacy score ("not at all confident") in "baseline self-efficacy in managing a patient's fluid levels" (P=.05). This study reveals that gains in knowledge with HPS do not equate to changes in critical thinking. It does expose the variables of older age, higher baseline knowledge and low self-efficacy in "managing a patient's fluid levels" as being predictive of higher critical thinking ability. Further study is warranted to determine the effect of repeated or sequential simulations (dosing) and timing after the HPS experience on critical thinking gains. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Extraction Method Plays Critical Role in Antibacterial Activity of Propolis-Loaded Hydrogels. (United States)

    de Lima, Gabriel G; de Souza, Ronaldo O; Bozzi, Aline D; Poplawska, Malgorzata A; Devine, Declan M; Nugent, Michael J D


    Extracted propolis has been used for a long time as a remedy. However, if the release rate of propolis is not controlled, the efficacy is reduced. To overcome this issue, extracted propolis was added to a cryogel system. Propolis collected from southern Brazil was extracted using different methods and loaded at different concentrations into polyvinyl alcohol (PVA) and polyacrylic acid hydrogels as carrier systems. The material properties were investigated with a focus on the propolis release profiles and the cryogel antibacterial properties against 4 different bacteria, namely: Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, and Pseudomonas putida. Swelling studies indicated that the swelling of the hydrogel was inversely related to propolis content. In addition, propolis release studies indicated a decreased release rate with increased propolis loading. PVA and PVA/polyacrylic acid-loaded propolis were effective against all 4 bacteria studied. These results indicate that the efficacy of propolis can be enhanced by incorporation into hydrogel carrier systems and that hydrogels with higher concentrations of propolis can be considered for use as bactericide dressing. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  14. A Model to Simulate Multimodality in a Mesoscopic Dynamic Network Loading Framework

    Directory of Open Access Journals (Sweden)

    Massimo Di Gangi


    Full Text Available A dynamic network loading (DNL model using a mesoscopic approach is proposed to simulate a multimodal transport network considering en-route change of the transport modes. The classic mesoscopic approach, where packets of users belonging to the same mode move following a path, is modified to take into account multiple modes interacting with each other, simultaneously and on the same multimodal network. In particular, to simulate modal change, functional aspects of multimodal arcs have been developed; those arcs are properly located on the network where modal change occurs and users are packed (or unpacked in a new modal resource that moves up to destination or to another multimodal arc. A test on a simple network reproducing a real situation is performed in order to show model peculiarities; some indicators, used to describe performances of the considered transport system, are shown.

  15. Prediction of Maximum Story Drift of MDOF Structures under Simulated Wind Loads Using Artificial Neural Networks

    Directory of Open Access Journals (Sweden)

    Omar Payán-Serrano


    Full Text Available The aim of this paper is to investigate the prediction of maximum story drift of Multi-Degree of Freedom (MDOF structures subjected to dynamics wind load using Artificial Neural Networks (ANNs through the combination of several structural and turbulent wind parameters. The maximum story drift of 1600 MDOF structures under 16 simulated wind conditions are computed with the purpose of generating the data set for the networks training with the Levenberg–Marquardt method. The Shinozuka and Newmark methods are used to simulate the turbulent wind and dynamic response, respectively. In order to optimize the computational time required for the dynamic analyses, an array format based on the Shinozuka method is presented to perform the parallel computing. Finally, it is observed that the already trained ANNs allow for predicting adequately the maximum story drift with a correlation close to 99%.

  16. International overview of high-level simulation education initiatives in relation to critical care. (United States)

    Alinier, Guillaume; Platt, Alan


    The use of simulation in health care education has become very topical across all professions and specialties in order to improve patient safety and quality of care. In the last decade, the adoption of more realistic simulation-based teaching methodologies, which serves as a bridge between the acquisition and application of clinical skills, knowledge, and attributes, has been accompanied by the development of a multitude of international and national simulation societies. These serve as important exchange fora for educators, clinicians, researchers, and engineers who desire to learn and share their experience and knowledge around simulation-based education. Several countries have derived their own strategy in order to promote the use of such training methodology. Current key national strategies will be presented in this paper alongside a discussion of their expected impact. Various approaches have been adopted and each has their own place and the potential to be adopted by other nations depending on their political, economic or even geographic context. Within the critical care arena, simulation has generated considerable interest and there is a growing evidence base for its use as a learning and teaching strategy within this environment. A number of critical care-related associations and societies are now recognizing simulation as an appropriate pedagogical approach and acknowledging its potential to improve patient care and clinical outcomes. Its implementation should be carefully considered to ensure that developments are based on current best educational practice to maximize the efficiency of these educational interventions. © 2013 British Association of Critical Care Nurses.

  17. Investigation on hardening behavior of metallic glass under cyclic indentation loading via molecular dynamics simulation (United States)

    Zhao, Dan; Zhao, Hongwei; Zhu, Bo; Wang, Shunbo


    Mechanical behavior of a Cu-Zr metallic glass (MG) under cyclic indentation loading is investigated via molecular dynamics simulation. A large-depth indentation after cycling is conducted, and the indentation curves show that hardening behavior occurs with cyclic indentation amplitudes exceeding elastic range. The atomic Von Mises shear strain distributions during the large-depth indentation are investigated, and the pre-existing plastic deformation induced by cyclic indentation is found to be the main contributor to the hardening behavior. By monitoring the atom trajectories and Voronoi atom volume, structure densification and free volume reduction phenomenon are found in the area beneath indenter after cycles. The accumulations of irreversible shear strain during cycling induce the area beneath indenter experience atom structure transition and become densified, thus the sample becomes more resistant to further deformation. In addition, the effects of temperatures and loading rates on the hardening behavior are studied. With higher temperature, more homogenous deformation and plasticity are produced, and then inducing more severe hardening in the MG. While with lower loading rate, the hardening phenomenon is found to be less severe because of the localization of shear strain during cycling.

  18. Finite strain formulation of viscoelastic damage model for simulation of fabric reinforced polymers under dynamic loading

    Directory of Open Access Journals (Sweden)

    Treutenaere S.


    Full Text Available The use of fabric reinforced polymers in the automotive industry is growing significantly. The high specific stiffness and strength, the ease of shaping as well as the great impact performance of these materials widely encourage their diffusion. The present model increases the predictability of explicit finite element analysis and push the boundaries of the ongoing phenomenological model. Carbon fibre composites made up various preforms were tested by applying different mechanical load up to dynamic loading. This experimental campaign highlighted the physical mechanisms affecting the initial mechanical properties, namely intra- and interlaminar matrix damage, viscoelasticty and fibre failure. The intralaminar behaviour model is based on the explicit formulation of the matrix damage model developed by the ONERA as the given damage formulation correlates with the experimental observation. Coupling with a Maxwell-Wiechert model, the viscoelasticity is included without losing the direct explicit formulation. Additionally, the model is formulated under a total Lagrangian scheme in order to maintain consistency for finite strain. Thus, the material frame-indifference as well as anisotropy are ensured. This allows reorientation of fibres to be taken into account particularly for in-plane shear loading. Moreover, fall within the framework of the total Lagrangian scheme greatly makes the parameter identification easier, as based on the initial configuration. This intralaminar model thus relies upon a physical description of the behaviour of fabric composites and the numerical simulations show a good correlation with the experimental results.

  19. Direct Numerical Simulations of Microstructure Effects During High-Rate Loading of Additively Manufactured Metals (United States)

    Battaile, Corbett; Owen, Steven; Moore, Nathan


    The properties of most engineering materials depend on the characteristics of internal microstructures and defects. In additively manufactured (AM) metals, these can include polycrystalline grains, impurities, phases, and significant porosity that qualitatively differ from conventional engineering materials. The microscopic details of the interactions between these internal defects, and the propagation of applied loads through the body, act in concert to dictate macro-observable properties like strength and compressibility. In this work, we used Sandia's ALEGRA finite element software to simulate the high-strain-rate loading of AM metals from laser engineered net shaping (LENS) and thermal spraying. The microstructural details of the material were represented explicitly, such that internal features like second phases and pores are captured and meshed as individual entities in the computational domain. We will discuss the dependence of the high-strain-rate mechanical properties on microstructural characteristics such as the shapes, sizes, and volume fractions of second phases and pores. In addition, we will examine how the details of the microstructural representation affect the microscopic material response to dynamic loads, and the effects of using ``stair-step'' versus conformal interfaces smoothed via the SCULPT tool in Sandia's CUBIT software. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the US DOE NNSA under contract DE-AC04-94AL85000.

  20. Numerical Simulation and Validation of a High Head Model Francis Turbine at Part Load Operating Condition (United States)

    Goyal, Rahul; Trivedi, Chirag; Kumar Gandhi, Bhupendra; Cervantes, Michel J.


    Hydraulic turbines are operated over an extended operating range to meet the real time electricity demand. Turbines operated at part load have flow parameters not matching the designed ones. This results in unstable flow conditions in the runner and draft tube developing low frequency and high amplitude pressure pulsations. The unsteady pressure pulsations affect the dynamic stability of the turbine and cause additional fatigue. The work presented in this paper discusses the flow field investigation of a high head model Francis turbine at part load: 50% of the rated load. Numerical simulation of the complete turbine has been performed. Unsteady pressure pulsations in the vaneless space, runner, and draft tube are investigated and validated with available experimental data. Detailed analysis of the rotor stator interaction and draft tube flow field are performed and discussed. The analysis shows the presence of a rotating vortex rope in the draft tube at the frequency of 0.3 times of the runner rotational frequency. The frequency of the vortex rope precession, which causes severe fluctuations and vibrations in the draft tube, is predicted within 3.9% of the experimental measured value. The vortex rope results pressure pulsations propagating in the system whose frequency is also perceive in the runner and upstream the runner.

  1. Preliminary modelling and mapping of critical loads for cadmium and lead in Europa

    NARCIS (Netherlands)

    Hettelingh JP; Slootweg J; Posch M; Ilyin I; MNV-CCE/WGE-IPC M& M Coordination Center for Effects; EMEP-Meteorological Synthesizing Centre-East


    De "Working Group on Effects" (WGE) van de "Convention on Long-range Transboundary Air Pollution" onder de "United Nations Economic Commission or Europe" (UNECE-CLRTAP) heeft tijdens haar 20e bijeenkomst besloten dat de methode om kritische depositiewaarden (critical

  2. A Study of the Use of Contact Loading to Simulate Low Velocity Impact (United States)

    Highsmith, Alton L.


    Although numerous studies on the impact response of laminated composites have been conducted, there is as yet no agreement within the composites community on what parameter or parameters are adequate for quantifying the severity of an impact event. One of the more interesting approaches that has been proposed uses the maximum contact force during impact to "quantify" the severity of the impact event, provided that the impact velocity is sufficiently low. A significant advantage of this approach, should it prove to be reliable, is that quasi-static contact loading could be used to simulate low velocity impact. In principle, a single specimen, loaded quasi-statically to successively increasing contact loads could be used to map the entire spectrum of damage as a function of maximum contact force. The present study had as its objective assessing whether or not the maximum contact force during impact is a suitable parameter for characterizing an impact. The response of [+/-60/0(sub 4)/+/-60/0(sub 2)](sub s) laminates fabricated from Fiberite T300/934 graphite epoxy and subjected to quasi-static contact loading and to low velocity impact was studied. Three quasi-static contact load levels - 525 lb., 600 lb., and 675 lb. - were selected. Three impact energy levels - 1.14 ft.-lb., 2.0 ft.-lb., and 2.60 ft.-lb. - were chosen in an effort to produce impact events in which the maximum contact forces during the impact events were 525 lb., 600 lb., and 625 lb., respectively. Damage development was documented using dye-penetrant enhanced x-ray radiography. A digital image processing technique was used to obtain quantitative information about the damage zone. Although it was intended that the impact load levels produce maximum contact forces equal to those used in the quasi-static contact experiments, larger contact forces were developed during impact loading. In spite of this, the damage zones developed in impacted specimens were smaller than the damage zones developed in

  3. Application of the simulation of a tank capacity proposal for loading and unloading process of bulk material

    Directory of Open Access Journals (Sweden)

    Janka Šaderová


    Full Text Available n this paper, the algorithm is given - how to design a tankfor bulk materials. An important part of the proposal is to setthe loading and unloading of a tank, which is also closely related to the proposal of its capacity and volume. Loading and unloadingprocess is dependent on several factors but the main are: method and speed of loading which represents the parameter - hour powerof loading device (e.g. continuous by a conveyor belt, method andspeed of unloading (continuousor at intervals and a typeand capacity of means of transport, in which the material loading (truck, rail car, conveyor belt system. The paper presents twomethods for determination of the loadingand unloading process - the graphic method and determination during the simulation -creating a simulation model.

  4. Physics Simulation Software for Autonomous Propellant Loading and Gas House Autonomous System Monitoring (United States)

    Regalado Reyes, Bjorn Constant


    1. Kennedy Space Center (KSC) is developing a mobile launching system with autonomous propellant loading capabilities for liquid-fueled rockets. An autonomous system will be responsible for monitoring and controlling the storage, loading and transferring of cryogenic propellants. The Physics Simulation Software will reproduce the sensor data seen during the delivery of cryogenic fluids including valve positions, pressures, temperatures and flow rates. The simulator will provide insight into the functionality of the propellant systems and demonstrate the effects of potential faults. This will provide verification of the communications protocols and the autonomous system control. 2. The High Pressure Gas Facility (HPGF) stores and distributes hydrogen, nitrogen, helium and high pressure air. The hydrogen and nitrogen are stored in cryogenic liquid state. The cryogenic fluids pose several hazards to operators and the storage and transfer equipment. Constant monitoring of pressures, temperatures and flow rates are required in order to maintain the safety of personnel and equipment during the handling and storage of these commodities. The Gas House Autonomous System Monitoring software will be responsible for constantly observing and recording sensor data, identifying and predicting faults and relaying hazard and operational information to the operators.

  5. Simulation analysis of rectangular dielectric-loaded traveling wave amplifiers for THz sources

    Directory of Open Access Journals (Sweden)

    Changbiao Wang


    Full Text Available Nonlinear simulation results for a 220-GHz rectangular dielectric-loaded traveling-wave amplifier are presented. Simulations are used to check a linear theory that is developed by phenomenological introduction of an effective dielectric parameter for electron beam channel, and it is found that the rf power gains from Pierce three-wave theory and particle simulations are in reasonable agreement. It is shown that the rf power gain during initial beam-wave interaction is positive; the falling on the initial rf power profile, which has been thought to be the rf power transferred to the beam for bunching buildup (negative gain effect, is probably resulting from numerical errors. Beam-wave interaction mechanism is analyzed by examining the evolution of beam bunching centers. Influences of various parameters on amplifier performance are examined, and transverse space-charge effect is analyzed. A symmetric excitation scheme for rf couplers is proposed, and rf field jumps on the common intersection line of vacuum, dielectric, and metal wall, which were found in rf simulations, are explained theoretically.

  6. Critical state and evolution of coordination number in simulated granular materials

    NARCIS (Netherlands)

    Rothenburg, L.; Kruyt, Nicolaas P.


    A theory of critical state and of the evolution of coordination number during quasi-static deformations of granular materials is developed, based on the interpretation of several discrete element simulations of plane granular assemblies with a range of interparticle friction from nearly frictionless

  7. Simulated and Virtual Science Laboratory Experiments: Improving Critical Thinking and Higher-Order Learning Skills (United States)

    Simon, Nicole A.


    Virtual laboratory experiments using interactive computer simulations are not being employed as viable alternatives to laboratory science curriculum at extensive enough rates within higher education. Rote traditional lab experiments are currently the norm and are not addressing inquiry, Critical Thinking, and cognition throughout the laboratory…

  8. The Impact of Simulation-Based Learning Experience on Critical Thinking Acquisition (United States)

    Rome, Candice


    The purpose of this comparative experimental project was to compare the impact of simulation-based learning experiences to traditional clinical rotations on critical thinking acquisition of associate nursing students within a maternal-child course. Innovative pedagogies have been integrated in nursing programs to augment inadequate clinical…

  9. Assessment of the Impact of Integrated Simulation on Critical Thinking and Clinical Judgment in Nursing Instruction (United States)

    Meyer, Rita Allen


    The purpose of this study was to explore the effects of using simulation and didactic instruction on critical thinking and clinical judgment with student nurses enrolled in a fall semester medical-surgical class. Specifically, it was of interest to compare the performance of these fall semester nursing students with the performance of nursing…

  10. More Than One Way to Debrief: A Critical Review of Healthcare Simulation Debriefing Methods. (United States)

    Sawyer, Taylor; Eppich, Walter; Brett-Fleegler, Marisa; Grant, Vincent; Cheng, Adam


    Debriefing is a critical component in the process of learning through healthcare simulation. This critical review examines the timing, facilitation, conversational structures, and process elements used in healthcare simulation debriefing. Debriefing occurs either after (postevent) or during (within-event) the simulation. The debriefing conversation can be guided by either a facilitator (facilitator-guided) or the simulation participants themselves (self-guided). Postevent facilitator-guided debriefing may incorporate several conversational structures. These conversational structures break the debriefing discussion into a series of 3 or more phases to help organize the debriefing and ensure the conversation proceeds in an orderly manner. Debriefing process elements are an array of techniques to optimize reflective experience and maximize the impact of debriefing. These are divided here into the following 3 categories: essential elements, conversational techniques/educational strategies, and debriefing adjuncts. This review provides both novice and advanced simulation educators with an overview of various methods of conducting healthcare simulation debriefing. Future research will investigate which debriefing methods are best for which contexts and for whom, and also explore how lessons from simulation debriefing translate to debriefing in clinical practice.

  11. Critical analysis of rhinovirus RNA load quantification by real-time reverse transcription-PCR. (United States)

    Schibler, Manuel; Yerly, Sabine; Vieille, Gaël; Docquier, Mylène; Turin, Lara; Kaiser, Laurent; Tapparel, Caroline


    Rhinoviruses are the most frequent cause of human respiratory infections, and quantitative rhinovirus diagnostic tools are needed for clinical investigations. Although results obtained by real-time reverse-transcription PCR (RT-PCR) assays are frequently converted to viral RNA loads, this presents several limitations regarding accurate virus RNA quantification, particularly given the need to reliably quantify all known rhinovirus genotypes with a single assay. Using an internal extraction control and serial dilutions of an in vitro-transcribed rhinovirus RNA reference standard, we validated a quantitative one-step real-time PCR assay. We then used chimeric rhinovirus genomes with 5'-untranslated regions (5'UTRs) originating from the three rhinovirus species and from one enterovirus to estimate the impact of the 5'UTR diversity. Respiratory specimens from infected patients were then also analyzed. The assay quantification ability ranged from 4.10 to 9.10 log RNA copies/ml, with an estimated error margin of ±10%. This variation was mainly linked to target variability and interassay variability. Taken together, our results indicate that our assay can reliably estimate rhinovirus RNA load, provided that the appropriate error margin is used. In contrast, due to the lack of a universal rhinovirus RNA standard and the variability related to sample collection procedures, accurate absolute rhinovirus RNA quantification in respiratory specimens is currently hardly feasible.

  12. In situ simulation: Taking reported critical incidents and adverse events back to the clinic

    DEFF Research Database (Denmark)

    Juul, Jonas; Paltved, Charlotte; Krogh, Kristian


    on interprofessional emergency teams, and 3) In situ simulation intervention study with evaluation of training. Reported critical incidents and adverse events will be collected from the Danish Patient Safety Database in the Central Denmark Region and analysed using the qualitative software programme NVivo 10...... with a contextual needs analysis and short-term observations might aid in scenario design for in situ simulation. This will shed light on how to develop specific learning goals for in situ simulation based on clinical challenges in acute healthcare settings. Third, in situ simulation offers a unique way to study...... simulation in continuing medical education for the health care professions: A systematic review. J Contin Educ Health Prof 2012; 32(4):243-254. (2) Flin R, O'Connor P, Crichton M. Safety at the sharp end. A guide to non-technical skills. England: Ashgate Publishing Ltd.; 2008. (3) Manser T. Teamwork...

  13. Critical System Cascading Collapse Assessment for Determining the Sensitive Transmission Lines and Severity of Total Loading Conditions

    Directory of Open Access Journals (Sweden)

    Nur Ashida Salim


    Full Text Available This paper presents a computationally accurate technique used to determine the estimated average probability of a system cascading collapse considering the effect of hidden failure on a protection system. This includes an accurate calculation of the probability of hidden failure as it will give significant effect on the results of the estimated average probability of system cascading collapse. The estimated average probability of a system cascading collapse is then used to determine the severe loading condition contributing to a higher risk of a system cascading collapse. This information is important because it will assist the utility to determine the maximum level of increase in the system loading condition before the occurrence of critical power system cascading collapse. Furthermore, the initial tripping of sensitive transmission line contributing to a critical system cascading collapse can also be determined by using the proposed method. Based on the results obtained from this study, it was found that selecting the accurate probability of hidden failure is very important as it will affect the estimated average probability of a system cascading collapse. Comparative study has been done with other techniques to verify the effectiveness of the proposed method used in the determination of sensitive transmission lines.

  14. Numerical and Experimental Investigation on the Structural Behaviour of a Horizontal Stabilizer under Critical Aerodynamic Loading Conditions

    Directory of Open Access Journals (Sweden)

    R. Sepe


    Full Text Available The aim of the proposed research activity is to investigate the mechanical behaviour of a part of aerospace horizontal stabilizer, made of composite materials and undergoing static loads. The prototype design and manufacturing phases have been carried out in the framework of this research activity. The structural components of such stabilizer are made of composite sandwich panels (HTA 5131/RTM 6 with honeycomb core (HRH-10-1/8-4.0; the sandwich skins have been made by means of Resin Transfer Moulding (RTM process. In order to assess the mechanical strength of this stabilizer, experimental tests have been performed. In particular, the most critical inflight recorded aerodynamic load has been experimentally reproduced and applied on the stabilizer. A numerical model, based on the Finite Element Method (FEM and aimed at reducing the experimental effort, has been preliminarily developed to calibrate amplitude, direction, and distribution of an equivalent and simpler load vector to be used in the experimental test. The FEM analysis, performed by using NASTRAN code, has allowed modelling the skins of the composite sandwich plates by definition of material properties and stack orientation of each lamina, while the honeycomb core has been modelled by using an equivalent orthotropic plate. Numerical and experimental results have been compared and a good agreement has been achieved.

  15. Numerical simulation of the low-cyclic loading of new-type assembled integral beam-column joints (United States)

    Wu, Jiangchuan; Zhang, Jiwen; Yin, Wanyun; Jin, Rencai


    In this paper, the low-cycle cyclic loading test and the elasto-plastic numerical simulation by OpenSEES of assembled integral beam-column joints of the three new prefabricated prestressed concrete beams are carried out. The key technologies such as unit selection, material model selection and prestressing in the numerical simulation of the new assembly-type beam-column joint is studied deeply. The results show that the relative model and parameters of the OpenSEES software can be used to simulate the hysteresis performance of the low-cycle cyclic loading of the new-type assembled integral beam-column joints.

  16. Methods for detecting early warnings of critical transitions in time series illustrated using simulated ecological data.

    Directory of Open Access Journals (Sweden)

    Vasilis Dakos

    Full Text Available Many dynamical systems, including lakes, organisms, ocean circulation patterns, or financial markets, are now thought to have tipping points where critical transitions to a contrasting state can happen. Because critical transitions can occur unexpectedly and are difficult to manage, there is a need for methods that can be used to identify when a critical transition is approaching. Recent theory shows that we can identify the proximity of a system to a critical transition using a variety of so-called 'early warning signals', and successful empirical examples suggest a potential for practical applicability. However, while the range of proposed methods for predicting critical transitions is rapidly expanding, opinions on their practical use differ widely, and there is no comparative study that tests the limitations of the different methods to identify approaching critical transitions using time-series data. Here, we summarize a range of currently available early warning methods and apply them to two simulated time series that are typical of systems undergoing a critical transition. In addition to a methodological guide, our work offers a practical toolbox that may be used in a wide range of fields to help detect early warning signals of critical transitions in time series data.

  17. [Care work load in critical patients. Comparative study NEMS versus NAS]. (United States)

    Bernat Adell, Amparo; Abizanda Campos, Ricardo; Yvars Bou, María; Quintana Bellmunt, Javier; Gascó García, Consuelo; Soriano Canuto, Montserrat; Reig Valero, Roberto; Vidal Tegedor, Bárbara


    The systems of calculating care load have not yet reached the levels of generalized use which the systems of prognostic estimation of survival have. The reason for this is their potential defects of design (medical and not nursing conceptualization) and the sometimes confusing completion (TISS 76). The simplest ("nine equivalents of nurse manpower use score" [NEMS], care levels) add the difficulty of not being useful for the calculation of staff, because the design is not oriented towards nursing. The development of NAS (nursing activity score) by FRICE tries to solve all these problems. Our objective has been to verify to what degree the NEMS and NAS are correlated as systems of expression and calculation of care load. During the last quarter of 2004, NEMS and NAS have been used simultaneously by the nursing staff. During this period, 150 pairs of daily calculation values of NEMS-NAS and 150 pairs of calculation values by shift of NEMS-NAS have been collected. Comparison of means and linear correlation of values obtained and the analysis of the histograms of values of each series, their value ranges and analysis of their bias coefficients have been done. The analysis was done with the SPSS/PC 11. During the period indicated, it has been verified that NEMS has a much narrower value range than NAS, both in regards to daily values (18-45 versus 29.70-84.50) and in regards to values by shift (18-45 versus 22.40-84.50). The bias analysis shows a deviation to the left of both series of values. Linear correlation between NEMS-NAS by shift shows a R2 of 0.1634 and becomes even poorer in the NEMS-NAS correlation per day with R2 of 0.2012. It should also be stressed that NEMS expresses its results in points while NAS does so in percentage of time occupied in the attention and care of the patient. In this preliminary study, the better adaptation of NAS versus NEMS to real work loads of patients hospitalized in the ICU and the non-possible correlation between the values of

  18. Eight critical factors in creating and implementing a successful simulation program. (United States)

    Lazzara, Elizabeth H; Benishek, Lauren E; Dietz, Aaron S; Salas, Eduardo; Adriansen, David J


    Recognizing the need to minimize human error and adverse events, clinicians, researchers, administrators, and educators have strived to enhance clinicians' knowledge, skills, and attitudes through training. Given the risks inherent in learning new skills or advancing underdeveloped skills on actual patients, simulation-based training (SBT) has become an invaluable tool across the medical education spectrum. The large simulation, training, and learning literature was used to provide a synthesized yet innovative and "memorable" heuristic of the important facets of simulation program creation and implementation, as represented by eight critical "S" factors-science, staff, supplies, space, support, systems, success, and sustainability. These critical factors advance earlier work that primarily focused on the science of SBT success, to also include more practical, perhaps even seemingly obvious but significantly challenging components of SBT, such as resources, space, and supplies. SYSTEMS: One of the eight critical factors-systems-refers to the need to match fidelity requirements to training needs and ensure that technological infrastructure is in place. The type of learning objectives that the training is intended to address should determine these requirements. For example, some simulators emphasize physical fidelity to enable clinicians to practice technical and nontechnical skills in a safe environment that mirrors real-world conditions. Such simulators are most appropriate when trainees are learning how to use specific equipment or conduct specific procedures. The eight factors-science, staff, supplies, space, support, systems, success, and sustainability-represent a synthesis of the most critical elements necessary for successful simulation programs. The order of the factors does not represent a deliberate prioritization or sequence, and the factors' relative importance may change as the program evolves.

  19. Evaluation of a new methodology to simulate damage and wear of polyethylene hip replacements subjected to edge loading in hip simulator testing. (United States)

    Partridge, Susan; Tipper, Joanne L; Al-Hajjar, Mazen; Isaac, Graham H; Fisher, John; Williams, Sophie


    Wear and fatigue of polyethylene acetabular cups have been reported to play a role in the failure of total hip replacements. Hip simulator testing under a wide range of clinically relevant loading conditions is important. Edge loading of hip replacements can occur following impingement under extreme activities and can also occur during normal gait, where there is an offset deficiency and/or joint laxity. This study evaluated a hip simulator method that assessed wear and damage in polyethylene acetabular liners that were subjected to edge loading. The liners tested to evaluate the method were a currently manufactured crosslinked polyethylene acetabular liner and an aged conventional polyethylene acetabular liner. The acetabular liners were tested for 5 million standard walking cycles and following this 5 million walking cycles with edge loading. Edge loading conditions represented a separation of the centers of rotation of the femoral head and the acetabular liner during the swing phase, leading to loading of the liner rim on heel strike. Rim damage and cracking was observed in the aged conventional polyethylene liner. Steady-state wear rates assessed gravimetrically were lower under edge loading compared to standard loading. This study supports previous clinical findings that edge loading may cause rim cracking in liners, where component positioning is suboptimal or where material degradation is present. The simulation method developed has the potential to be used in the future to test the effect of aging and different levels of severity of edge loading on a range of cross-linked polyethylene materials. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017. © 2017 Wiley Periodicals, Inc.

  20. Scaling up watershed model parameters--Flow and load simulations of the Edisto River Basin (United States)

    Feaster, Toby D.; Benedict, Stephen T.; Clark, Jimmy M.; Bradley, Paul M.; Conrads, Paul


    The Edisto River is the longest and largest river system completely contained in South Carolina and is one of the longest free flowing blackwater rivers in the United States. The Edisto River basin also has fish-tissue mercury concentrations that are some of the highest recorded in the United States. As part of an effort by the U.S. Geological Survey to expand the understanding of relations among hydrologic, geochemical, and ecological processes that affect fish-tissue mercury concentrations within the Edisto River basin, analyses and simulations of the hydrology of the Edisto River basin were made with the topography-based hydrological model (TOPMODEL). The potential for scaling up a previous application of TOPMODEL for the McTier Creek watershed, which is a small headwater catchment to the Edisto River basin, was assessed. Scaling up was done in a step-wise process beginning with applying the calibration parameters, meteorological data, and topographic wetness index data from the McTier Creek TOPMODEL to the Edisto River TOPMODEL. Additional changes were made with subsequent simulations culminating in the best simulation, which included meteorological and topographic wetness index data from the Edisto River basin and updated calibration parameters for some of the TOPMODEL calibration parameters. Comparison of goodness-of-fit statistics between measured and simulated daily mean streamflow for the two models showed that with calibration, the Edisto River TOPMODEL produced slightly better results than the McTier Creek model, despite the significant difference in the drainage-area size at the outlet locations for the two models (30.7 and 2,725 square miles, respectively). Along with the TOPMODEL hydrologic simulations, a visualization tool (the Edisto River Data Viewer) was developed to help assess trends and influencing variables in the stream ecosystem. Incorporated into the visualization tool were the water-quality load models TOPLOAD, TOPLOAD-H, and LOADEST

  1. Inverse Load Calculation of Wind Turbine Support Structures - A Numerical Verification Using the Comprehensive Simulation Code FAST: Preprint (Revised)

    Energy Technology Data Exchange (ETDEWEB)

    Pahn, T.; Jonkman, J.; Rolges, R.; Robertson, A.


    Physically measuring the dynamic responses of wind turbine support structures enables the calculation of the applied loads using an inverse procedure. In this process, inverse means deriving the inputs/forces from the outputs/responses. This paper presents results of a numerical verification of such an inverse load calculation. For this verification, the comprehensive simulation code FAST is used. FAST accounts for the coupled dynamics of wind inflow, aerodynamics, elasticity and turbine controls. Simulations are run using a 5-MW onshore wind turbine model with a tubular tower. Both the applied loads due to the instantaneous wind field and the resulting system responses are known from the simulations. Using the system responses as inputs to the inverse calculation, the applied loads are calculated, which in this case are the rotor thrust forces. These forces are compared to the rotor thrust forces known from the FAST simulations. The results of these comparisons are presented to assess the accuracy of the inverse calculation. To study the influences of turbine controls, load cases in normal operation between cut-in and rated wind speed, near rated wind speed and between rated and cut-out wind speed are chosen. The presented study shows that the inverse load calculation is capable of computing very good estimates of the rotor thrust. The accuracy of the inverse calculation does not depend on the control activity of the wind turbine.

  2. Strain Response of the Anterior Cruciate Ligament to Uniplanar and Multiplanar Loads During Simulated Landings: Implications for Injury Mechanism. (United States)

    Kiapour, Ata M; Demetropoulos, Constantine K; Kiapour, Ali; Quatman, Carmen E; Wordeman, Samuel C; Goel, Vijay K; Hewett, Timothy E


    Despite basic characterization of the loading factors that strain the anterior cruciate ligament (ACL), the interrelationship(s) and additive nature of these loads that occur during noncontact ACL injuries remain incompletely characterized. In the presence of an impulsive axial compression, simulating vertical ground-reaction force during landing (1) both knee abduction and internal tibial rotation moments would result in increased peak ACL strain, and (2) a combined multiplanar loading condition, including both knee abduction and internal tibial rotation moments, would increase the peak ACL strain to levels greater than those under uniplanar loading modes alone. Controlled laboratory study. A cadaveric model of landing was used to simulate dynamic landings during a jump in 17 cadaveric lower extremities (age, 45 ± 7 years; 9 female and 8 male). Peak ACL strain was measured in situ and characterized under impulsive axial compression and simulated muscle forces (baseline) followed by addition of anterior tibial shear, knee abduction, and internal tibial rotation loads in both uni- and multiplanar modes, simulating a broad range of landing conditions. The associations between knee rotational kinematics and peak ACL strain levels were further investigated to determine the potential noncontact injury mechanism. Externally applied loads, under both uni- and multiplanar conditions, resulted in consistent increases in peak ACL strain compared with the baseline during simulated landings (by up to 3.5-fold; P ≤ .032). Combined multiplanar loading resulted in the greatest increases in peak ACL strain (P anterior tibial shear force, knee abduction, and internal tibial rotation moments significantly increases ACL strain, which could result in ACL failure. These findings support multiplanar knee valgus collapse as one the primary mechanisms of noncontact ACL injuries during landing. Intervention programs that address multiple planes of loading may decrease the risk of ACL

  3. Training simulator for modern load dispatching centers; Trainingssimulator fuer modernen Lastverteiler

    Energy Technology Data Exchange (ETDEWEB)

    Nordieker, B. [BKW Energie AG, Bern (Switzerland); Imhof, K. [ABB Network Partner AG, Turgi (Switzerland)


    The recent completion of the second stage of a modernization programme being carried out at the load dispatching center of BKW Energie AG, a Swiss utility with headquarters in Berne, included the start-up of a dispatcher training simulator (DTS). Besides being used to train dispatchers and staff engineers, the simulator also offers many advantages for routine power system operation. The DTS is integrated in the Energy Management System, the standby computer acting as server. If required, the simulator can also be run on the on-line computer. Two full graphics workstations are provided to enable trainees to work in an environment that approximates real-world conditions. (orig.) [Deutsch] Mit der Inbetriebnahme der zweiten Ausbaustufe des neuen Lastverteilers der BKW Energie AG Bern, steht fuer den Netzbetrieb der BKW ein Trainingssimulator zur Verfuegung. Er dient in erster Linie der Aus- und Weiterbildung der Dispatcher und Betriebsingenieure, bietet aber darueber hinaus zahlreiche Vorteile fuer den taeglichen Netzbetrieb. Der BKW-Trainingssimulator ist in das Energie-Management-System (EMS) integriert. Als Server dient der entsprechende Standby-Rechner. Der Trainingssimulator laeuft bei Bedarf auch auf dem Online-Rechner. Als Arbeitsinstrumente fuer Lehrer und Schueler (Dispatcher) dienen zwei beliebige vollgraphische Arbeitsplaetze. (orig.)

  4. A perfusion bioreactor system efficiently generates cell‐loaded bone substitute materials for addressing critical size bone defects (United States)

    Kleinhans, Claudia; Mohan, Ramkumar Ramani; Vacun, Gabriele; Schwarz, Thomas; Haller, Barbara; Sun, Yang; Kahlig, Alexander; Kluger, Petra; Finne‐Wistrand, Anna; Walles, Heike


    Abstract Critical size bone defects and non‐union fractions are still challenging to treat. Cell‐loaded bone substitutes have shown improved bone ingrowth and bone formation. However, a lack of methods for homogenously colonizing scaffolds limits the maximum volume of bone grafts. Additionally, therapy robustness is impaired by heterogeneous cell populations after graft generation. Our aim was to establish a technology for generating grafts with a size of 10.5 mm in diameter and 25 mm of height, and thus for grafts suited for treatment of critical size bone defects. Therefore, a novel tailor‐made bioreactor system was developed, allowing standardized flow conditions in a porous poly(L‐lactide‐co‐caprolactone) material. Scaffolds were seeded with primary human mesenchymal stem cells derived from four different donors. In contrast to static experimental conditions, homogenous cell distributions were accomplished under dynamic culture. Additionally, culture in the bioreactor system allowed the induction of osteogenic lineage commitment after one week of culture without addition of soluble factors. This was demonstrated by quantitative analysis of calcification and gene expression markers related to osteogenic lineage. In conclusion, the novel bioreactor technology allows efficient and standardized conditions for generating bone substitutes that are suitable for the treatment of critical size defects in humans. PMID:26011163

  5. [Selection and optimal sequence of critical elements for medication review: A simulation with hospital pharmacy residents]. (United States)

    Dubois, S; Barbier, A; Thibault, M; Atkinson, S; Bussières, J-F


    The main objective of this study was to compare the responses of pharmacy residents regarding critical steps for medication order review, in the presence or absence of clinical pharmacists on patient care units, to describe the sequence of these steps and to compare them to an optimal sequence. The secondary objectives were to test this sequence in a simulation and to assess the residents' level of agreement on medication order review. Twenty-two validation steps were selected from guidelines. A simulation on order review was organized in three steps: selecting elements judged to be necessary or not for the order review critical path, then organizing this sequence in chronological order, implementation of this critical path on two simulated practical cases, resident perceptions about order review in their training. Forty-one residents participated in the activity. Responses were heterogeneous regarding the elements' sequence and the time required for the review of a simulated case (3-13minutes). A majority of residents considered that their training was insufficient (29/41), that pharmacists validated differently (27/41), and that it was impossible to review the 22 proposed items for each prescription (30/41). This article highlights heterogeneous medication order review practices among pharmacy residents, due to a lack of training in their curriculum according to them. It is essential to acquire medication order review standard both locally and nationally. Copyright © 2016 Académie Nationale de Pharmacie. Published by Elsevier Masson SAS. All rights reserved.

  6. Design of a Mobile Agent-Based Adaptive Communication Middleware for Federations of Critical Infrastructure Simulations (United States)

    Görbil, Gökçe; Gelenbe, Erol

    The simulation of critical infrastructures (CI) can involve the use of diverse domain specific simulators that run on geographically distant sites. These diverse simulators must then be coordinated to run concurrently in order to evaluate the performance of critical infrastructures which influence each other, especially in emergency or resource-critical situations. We therefore describe the design of an adaptive communication middleware that provides reliable and real-time one-to-one and group communications for federations of CI simulators over a wide-area network (WAN). The proposed middleware is composed of mobile agent-based peer-to-peer (P2P) overlays, called virtual networks (VNets), to enable resilient, adaptive and real-time communications over unreliable and dynamic physical networks (PNets). The autonomous software agents comprising the communication middleware monitor their performance and the underlying PNet, and dynamically adapt the P2P overlay and migrate over the PNet in order to optimize communications according to the requirements of the federation and the current conditions of the PNet. Reliable communications is provided via redundancy within the communication middleware and intelligent migration of agents over the PNet. The proposed middleware integrates security methods in order to protect the communication infrastructure against attacks and provide privacy and anonymity to the participants of the federation. Experiments with an initial version of the communication middleware over a real-life networking testbed show that promising improvements can be obtained for unicast and group communications via the agent migration capability of our middleware.

  7. Colistin Population Pharmacokinetics after Application of a Loading Dose of 9 MU Colistin Methanesulfonate in Critically Ill Patients (United States)

    Friberg, Lena E.; Pontikis, Konstantinos; Ioannidis, Konstantinos; Tsagkari, Vasiliki; Galani, Lamprini; Kostakou, Eirini; Baziaka, Fotini; Paskalis, Charalambos; Koutsoukou, Antonia; Giamarellou, Helen


    Colistin has been revived, in the era of extensively drug-resistant (XDR) Gram-negative infections, as the last-resort treatment in critically ill patients. Recent studies focusing on the optimal dosing strategy of colistin have demonstrated the necessity of a loading dose at treatment initiation (D. Plachouras, M. Karvanen, L. E. Friberg, E. Papadomichelakis, A. Antoniadou, I. Tsangaris, I. Karaiskos, G. Poulakou, F. Kontopidou, A. Armaganidis, O. Cars, and H. Giamarellou, Antimicrob Agents Chemother 53:3430–3436, 2009,; A. F. Mohamed, I. Karaiskos, D. Plachouras, M. Karvanen, K. Pontikis, B. Jansson, E. Papadomichelakis, A. Antoniadou, H. Giamarellou, A. Armaganidis, O. Cars, and L. E. Friberg, Antimicrob Agents Chemother 56:4241– 4249, 2012,; S. M. Garonzik, J. Li, V. Thamlikitkul, D. L. Paterson, S. Shoham, J. Jacob, F. P. Silveira, A. Forrest, and R. L. Nation, Antimicrob Agents Chemother 55:3284–3294, 2011, In 19 critically ill patients with suspected or microbiologically documented infections caused by XDR Gram-negative strains, a loading dose of 9 MU colistin methanesulfonate (CMS) (∼270 mg colistin base activity) was administered with a maintenance dose of 4.5 MU every 12 h, commenced after 24 h. Patients on renal replacement were excluded. CMS infusion was given over 30 min or 1 h. Repeated blood sampling was performed after the loading dose and after the 5th or 6th dose. Colistin concentrations and measured CMS, determined after hydrolization to colistin and including the partially sulfomethylated derivatives, were determined with a liquid chromatography-tandem mass spectrometry assay. Population pharmacokinetic analysis was conducted in NONMEM with the new data combined with data from previous studies. Measured colistimethate concentrations were described by 4 compartments for distribution and removal of sulfomethyl groups

  8. Contribution of static and dynamic load balancing in a real-time distributed air defence simulation

    CSIR Research Space (South Africa)

    Duvenhage, B


    Full Text Available the analysis and the available literature the appropriate metrics and a static load balancing heuristic is chosen and its performance compared to that of the statistical static load balancing. The dynamic suitability of the static load balancing schemes... metrics are applied to these distributions to find a subset of metrics applicable to static load balancing and a static load balancing heuristic. 3.1 The Static Optimisation Problem A simple way to perform static load balancing is to randomly assign...

  9. Mission and Safety Critical (MASC): An EVACS simulation with nested transactions (United States)

    Auty, David; Atkinson, Colin; Randall, Charlie


    The Extra-Vehicular Activity Control System (EVACS) Simulation with Nested Transactions, a recent effort of the MISSION Kernel Team, is documented. The EVACS simulation is a simulation of some aspects of the Extra-Vehicular Activity Control System, in particular, just the selection of communication frequencies. The simulation is a tool to explore mission and safety critical (MASC) applications. For the purpose of this effort, its current definition is quite narrow serving only as a starting point for prototyping purposes. (Note that EVACS itself has been supplanted in a larger scenario of a lunar outpost with astronauts and a lunar rover). The frequency selection scenario was modified to embed its processing in nested transactions. Again as a first step, only two aspects of transaction support were implemented in this prototype: architecture and state recovery. Issues of concurrency and distribution are yet to be addressed.

  10. A Survey on Investigating the Need for Intelligent Power-Aware Load Balanced Routing Protocols for Handling Critical Links in MANETs

    Directory of Open Access Journals (Sweden)

    B. Sivakumar


    Full Text Available In mobile ad hoc networks connectivity is always an issue of concern. Due to dynamism in the behavior of mobile nodes, efficiency shall be achieved only with the assumption of good network infrastructure. Presence of critical links results in deterioration which should be detected in advance to retain the prevailing communication setup. This paper discusses a short survey on the specialized algorithms and protocols related to energy efficient load balancing for critical link detection in the recent literature. This paper also suggests a machine learning based hybrid power-aware approach for handling critical nodes via load balancing.

  11. A Damage Model for the Simulation of Delamination in Advanced Composites under Variable-Mode Loading (United States)

    Turon, A.; Camanho, P. P.; Costa, J.; Davila, C. G.


    A thermodynamically consistent damage model is proposed for the simulation of progressive delamination in composite materials under variable-mode ratio. The model is formulated in the context of Damage Mechanics. A novel constitutive equation is developed to model the initiation and propagation of delamination. A delamination initiation criterion is proposed to assure that the formulation can account for changes in the loading mode in a thermodynamically consistent way. The formulation accounts for crack closure effects to avoid interfacial penetration of two adjacent layers after complete decohesion. The model is implemented in a finite element formulation, and the numerical predictions are compared with experimental results obtained in both composite test specimens and structural components.

  12. Modeling and Simulation of Coal Loading by Cutting Drum in Flat Seams (United States)

    Gospodarczyk, Piotr


    This paper presents a methodology for modeling work of a coal shearer work in low longwall coal seams where the wall height does not exceed 1.5 m. In such conditions, an important issue is the process of loading the ore from shearer cutting drum on an armored face conveyor and selection of appropriate kinematic parameters to avoid choking. Discrete element method was used to model coal seam. This method allows for efficient simulation of physical systems composed of many separate components. Methods and algorithms based on existing theoretical models were developed to imitate coal cutting process. Main focus of analysis was put on coal stream movement for different variants of the shearer construction and kinematic parameters.

  13. Parallel-tempering cluster algorithm for computer simulations of critical phenomena. (United States)

    Bittner, Elmar; Janke, Wolfhard


    In finite-size scaling analyses of Monte Carlo simulations of second-order phase transitions one often needs an extended temperature range around the critical point. By combining the parallel-tempering algorithm with cluster updates and an adaptive routine to find the temperature window of interest, we introduce a flexible and powerful method for systematic investigations of critical phenomena. As a result, we gain one to two orders of magnitude in the performance for two- and three-dimensional Ising models in comparison with the recently proposed Wang-Landau recursion for cluster algorithms based on the multibondic algorithm, which is already a great improvement over the standard multicanonical variant.

  14. Numerical Simulations of Fluid Flow in a Single Fracture under Loading and Unloading Conditions (United States)

    Kling, T.; Huo, D.; Schwarz, J. O.; Enzmann, F.; Blum, P.; Benson, S. M.


    Hydraulic aperture is one of the most important parameters to describe fluid flow in fractured rocks. Hydraulic apertures are typically determined indirectly by fluid flow experiments or hydraulic field tests based on the cubic law. Alternatively, there are different equations approximating an empirical relation between mechanical and hydraulic aperture. However, these methods most widely neglect mechanisms such as stress changes, where increasing stresses decrease the mechanical aperture and, therefore, also the effective hydraulic aperture. Hence, the objective of the present study is to simulate fluid flow in a single fracture under loading/unloading conditions and validate the results with core flooding experiments. Core flooding data and X-ray CT scans (voxel size 0.5 x 0.5 x 1 mm) of a sandstone sample with a single fracture (measured mean aperture of around 0.1 mm) were obtained by laboratory experiments. The fluid flow simulations are performed by solving the incompressible Navier-Stokes equation by using a finite volume method. Input data are given by experimental flow rates, pressures, applied stress levels and CT images of the fracture. In addition, an error analysis is performed to establish confidence in results. Results of the validation exhibit significant effects of stress on aperture distribution such as channeling and stress-dependent fracture permeability. A significant stress sensitivity of hydraulic aperture compared to the mechanical aperture was found, which can be explained by roughness changes resulting from loading. Observations indicate that with increasing stress, changes in mechanical aperture are small, while changes in hydraulic aperture can be very large. Since previous equations for hydraulic aperture do not consider changes in normal stress, a modification of these equations is proposed, including the stress-dependency of mechanical apertures to provide a better approximation to the observed hydraulic apertures.

  15. Reliability and validity of a basketball-specific fatigue protocol simulating match load

    Directory of Open Access Journals (Sweden)

    Karel Hůlka


    Full Text Available Background: Research on the amount and type of fatigue caused by match load depends on protocols based on time-motion analysis of match performance in a given sport. The role of these protocols is to accurately simulate specific player match load, which is, contrary to a match, identical for all participants. Objective: The purpose of the study was to determine the reliability and validity using a basketball-specific fatigue protocol simulating player's performance during a basketball match. Methods: The study involved a total of 25 male basketball players (age 17.4 ± 1.5 years; body height 185.1 ± 7.4 cm and body mass index 22.1 ± 0.3 kg ⋅ m-2 of U17 and U19 categories. The participants performed a specific basketball fatigue protocol twice during 14 days consisting of four periods separated by breaks as in a basketball match. Each period contained a stage with maximum intensity activities followed by a stage of medium intensity and low intensity. During the protocol, heart rate was recorded and time intervals of maximum, medium and low intensity were measured. Results: The relative reliability measurement pointed to high intra-individual stability of the results, when intraclass correlation coefficient varied from .71 to .92. The typical error of measurement showed that the players should be able to repeat the measurement with less than 1.31 s (0.82% in total time, 0.17 s (2.73% in sprint time, and 1.32% (1.19% for percentage of heart rate. The values 1.68 (38.35% of Sprint decrement showed very low repeatability.Conclusion: Measurements using a fatigue protocol showed high validity, reliability, and agreement of repeated measures.

  16. Simulating ideal assistive devices to reduce the metabolic cost of walking with heavy loads.

    Directory of Open Access Journals (Sweden)

    Christopher L Dembia

    Full Text Available Wearable robotic devices can restore and enhance mobility. There is growing interest in designing devices that reduce the metabolic cost of walking; however, designers lack guidelines for which joints to assist and when to provide the assistance. To help address this problem, we used musculoskeletal simulation to predict how hypothetical devices affect muscle activity and metabolic cost when walking with heavy loads. We explored 7 massless devices, each providing unrestricted torque at one degree of freedom in one direction (hip abduction, hip flexion, hip extension, knee flexion, knee extension, ankle plantarflexion, or ankle dorsiflexion. We used the Computed Muscle Control algorithm in OpenSim to find device torque profiles that minimized the sum of squared muscle activations while tracking measured kinematics of loaded walking without assistance. We then examined the metabolic savings provided by each device, the corresponding device torque profiles, and the resulting changes in muscle activity. We found that the hip flexion, knee flexion, and hip abduction devices provided greater metabolic savings than the ankle plantarflexion device. The hip abduction device had the greatest ratio of metabolic savings to peak instantaneous positive device power, suggesting that frontal-plane hip assistance may be an efficient way to reduce metabolic cost. Overall, the device torque profiles generally differed from the corresponding net joint moment generated by muscles without assistance, and occasionally exceeded the net joint moment to reduce muscle activity at other degrees of freedom. Many devices affected the activity of muscles elsewhere in the limb; for example, the hip flexion device affected muscles that span the ankle joint. Our results may help experimentalists decide which joint motions to target when building devices and can provide intuition for how devices may interact with the musculoskeletal system. The simulations are freely available

  17. Simulating ideal assistive devices to reduce the metabolic cost of walking with heavy loads (United States)

    Silder, Amy; Uchida, Thomas K.; Hicks, Jennifer L.; Delp, Scott L.


    Wearable robotic devices can restore and enhance mobility. There is growing interest in designing devices that reduce the metabolic cost of walking; however, designers lack guidelines for which joints to assist and when to provide the assistance. To help address this problem, we used musculoskeletal simulation to predict how hypothetical devices affect muscle activity and metabolic cost when walking with heavy loads. We explored 7 massless devices, each providing unrestricted torque at one degree of freedom in one direction (hip abduction, hip flexion, hip extension, knee flexion, knee extension, ankle plantarflexion, or ankle dorsiflexion). We used the Computed Muscle Control algorithm in OpenSim to find device torque profiles that minimized the sum of squared muscle activations while tracking measured kinematics of loaded walking without assistance. We then examined the metabolic savings provided by each device, the corresponding device torque profiles, and the resulting changes in muscle activity. We found that the hip flexion, knee flexion, and hip abduction devices provided greater metabolic savings than the ankle plantarflexion device. The hip abduction device had the greatest ratio of metabolic savings to peak instantaneous positive device power, suggesting that frontal-plane hip assistance may be an efficient way to reduce metabolic cost. Overall, the device torque profiles generally differed from the corresponding net joint moment generated by muscles without assistance, and occasionally exceeded the net joint moment to reduce muscle activity at other degrees of freedom. Many devices affected the activity of muscles elsewhere in the limb; for example, the hip flexion device affected muscles that span the ankle joint. Our results may help experimentalists decide which joint motions to target when building devices and can provide intuition for how devices may interact with the musculoskeletal system. The simulations are freely available online, allowing

  18. Elastic behavior of brain simulants in comparison to porcine brain at different loading velocities. (United States)

    Falland-Cheung, Lisa; Scholze, Mario; Hammer, Niels; Waddell, J Neil; Tong, Darryl C; Brunton, Paul A


    Blunt force impacts to the head and the resulting internal force transmission to the brain and other cranial tissue are difficult to measure. To model blunt force impact scenarios, the compressive properties resembling tissue elasticity are of importance. Therefore, this study investigated and compared the elastic behavior of gelatin, alginate, agar/glycerol and agar/glycerol/water simulant materials to that of porcine brain in a fresh and unfixed condition. Specimens, 10 × 10 × 10mm 3 , were fabricated and tested at 22°C, apart from gelatin which was conditioned to 4°C prior to testing. For comparison, fresh porcine brains were sourced and prepared to the same dimensions as the simulants. Specimens underwent compression tests at crosshead displacement rates of 2.5, 10 and 16mms -1 (equivalent to strain rates of 0.25, 1 and 1.6s -1 ), obtaining apparent elastic moduli values at different strain rate intervals (0-0.2, 0.2-0.4 and 0.4-0.5). The results of this study indicate that overall all simulant materials had an apparent elastic moduli similar in magnitude across all strain ranges compared to brain, even though comparatively higher, especially the apparent elastic moduli values of alginate. In conclusion, while agar/glycerol/water and agar/glycerol had similar apparent elastic moduli in magnitude and the closest apparent elastic moduli in the initial strain range (E 1 ), gelatin showed the most similar values to fresh porcine brain at the transitional (E 2 ) and higher strain range (E 3 ). The simulant materials and the fresh porcine brain exhibited strain rate dependent behavior, with increasing elastic moduli upon increasing loading velocities. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Simulated mussel mortality thresholds as a function of mussel biomass and nutrient loading (United States)

    Bril, Jeremy S.; Langenfeld, Kathryn; Just, Craig L.; Spak, Scott N.; Newton, Teresa


    A freshwater “mussel mortality threshold” was explored as a function of porewater ammonium (NH4+) concentration, mussel biomass, and total nitrogen (N) utilizing a numerical model calibrated with data from mesocosms with and without mussels. A mortality threshold of 2 mg-N L−1 porewater NH4+ was selected based on a study that estimated 100% mortality of juvenile Lampsilis mussels exposed to 1.9 mg-N L−1NH4+ in equilibrium with 0.18 mg-N L−1 NH3. At the highest simulated mussel biomass (560 g m−2) and the lowest simulated influent water “food” concentration (0.1 mg-N L−1), the porewater NH4+ concentration after a 2,160 h timespan without mussels was 0.5 mg-N L−1 compared to 2.25 mg-N L−1 with mussels. Continuing these simulations while varying mussel biomass and N content yielded a mortality threshold contour that was essentially linear which contradicted the non-linear and non-monotonic relationship suggested by Strayer (2014). Our model suggests that mussels spatially focus nutrients from the overlying water to the sediments as evidenced by elevated porewater NH4+ in mesocosms with mussels. However, our previous work and the model utilized here show elevated concentrations of nitrite and nitrate in overlying waters as an indirect consequence of mussel activity. Even when the simulated overlying water food availability was quite low, the mortality threshold was reached at a mussel biomass of about 480 g m−2. At a food concentration of 10 mg-N L−1, the mortality threshold was reached at a biomass of about 250 g m−2. Our model suggests the mortality threshold for juvenile Lampsilis species could be exceeded at low mussel biomass if exposed for even a short time to the highly elevated total N loadings endemic to the agricultural Midwest.

  20. Critical loads of sulphur and nitrogen for freshwaters in Great Britain and assessment of deposition reduction requirements with the First-order Acidity Balance (FAB model

    Directory of Open Access Journals (Sweden)

    C. Curtis


    Full Text Available The critical loads approach is widely used within Europe to assess the impacts of acid deposition on terrestrial and freshwater ecosystems. Recent work in Great Britain has focused on the national application of the First-order Acidity Balance (FAB model to a freshwaters dataset of 1470 lake and stream water chemistry samples from sites across Britain which were selected to represent the most sensitive water bodies in their corresponding 10 km grid square. A ``Critical Load Function' generated for each site is compared with the deposition load of S and N at the time of water chemistry sampling. The model predicts that when catchment processes reach steady-state with these deposition levels, increases in nitrate leaching will depress acid neutralizing capacity (ANC below the critical threshold of 0 μeql-1 at more than a quarter of the sites sampled, i.e. the critical load of acid deposition is exceeded at these sites. The critical load exceedances are generally found in upland regions of high deposition where acidification has been previously recognised, but critical loads in large areas of western Scotland are also exceeded where little biological evidence of acidification has yet been found. There is a regional variation in the deposition reduction requirements for protection of the sampled sites. The FAB model indicates that in Scotland, most of the sampled sites could be protected by sufficiently large reductions in S deposition alone. In the English and Welsh uplands, both S and N deposition must be reduced to protect the sites. Current international commitments to reduce S deposition throughout Europe will therefore be insufficient to protect the most sensitive freshwaters in England and Wales. Keywords: critical loads; acidification; nitrate; FAB model; acid deposition

  1. Francis-99: Transient CFD simulation of load changes and turbine shutdown in a model sized high-head Francis turbine (United States)

    Mössinger, Peter; Jester-Zürker, Roland; Jung, Alexander


    With increasing requirements for hydropower plant operation due to intermittent renewable energy sources like wind and solar, numerical simulations of transient operations in hydraulic turbo machines become more important. As a continuation of the work performed for the first workshop which covered three steady operating conditions, in the present paper load changes and a shutdown procedure are investigated. The findings of previous studies are used to create a 360° model and compare measurements with simulation results for the operating points part load, high load and best efficiency. A mesh motion procedure is introduced, allowing to represent moving guide vanes for load changes from best efficiency to part load and high load. Additionally an automated re-mesh procedure is added for turbine shutdown to ensure reliable mesh quality during guide vane closing. All three transient operations are compared to PIV velocity measurements in the draft tube and pressure signals in the vaneless space. Simulation results of axial velocity distributions for all three steady operation points, during both load changes and for the shutdown correlated well with the measurement. An offset at vaneless space pressure is found to be a result of guide vane corrections for the simulation to ensure similar velocity fields. Short-time Fourier transformation indicating increasing amplitudes and frequencies at speed-no load conditions. Further studies will discuss the already measured start-up procedure and investigate the necessity to consider the hydraulic system dynamics upstream of the turbine by means of a 1D3D coupling between the 3D flow field and a 1D system model.

  2. Computational methods for predicting the response of critical as-built infrastructure to dynamic loads (architectural surety)

    Energy Technology Data Exchange (ETDEWEB)

    Preece, D.S.; Weatherby, J.R.; Attaway, S.W.; Swegle, J.W.; Matalucci, R.V.


    Coupled blast-structural computational simulations using supercomputer capabilities will significantly advance the understanding of how complex structures respond under dynamic loads caused by explosives and earthquakes, an understanding with application to the surety of both federal and nonfederal buildings. Simulation of the effects of explosives on structures is a challenge because the explosive response can best be simulated using Eulerian computational techniques and structural behavior is best modeled using Lagrangian methods. Due to the different methodologies of the two computational techniques and code architecture requirements, they are usually implemented in different computer programs. Explosive and structure modeling in two different codes make it difficult or next to impossible to do coupled explosive/structure interaction simulations. Sandia National Laboratories has developed two techniques for solving this problem. The first is called Smoothed Particle Hydrodynamics (SPH), a relatively new gridless method comparable to Eulerian, that is especially suited for treating liquids and gases such as those produced by an explosive. The SPH capability has been fully implemented into the transient dynamics finite element (Lagrangian) codes PRONTO-2D and -3D. A PRONTO-3D/SPH simulation of the effect of a blast on a protective-wall barrier is presented in this paper. The second technique employed at Sandia National Laboratories uses a relatively new code called ALEGRA which is an ALE (Arbitrary Lagrangian-Eulerian) wave code with specific emphasis on large deformation and shock propagation. ALEGRA is capable of solving many shock-wave physics problems but it is especially suited for modeling problems involving the interaction of decoupled explosives with structures.

  3. Modeling and Simulation of the Thermal Runaway Behavior of Cylindrical Li-Ion Cells—Computing of Critical Parameters

    Directory of Open Access Journals (Sweden)

    Andreas Melcher


    Full Text Available The thermal behavior of Li-ion cells is an important safety issue and has to be known under varying thermal conditions. The main objective of this work is to gain a better understanding of the temperature increase within the cell considering different heat sources under specified working conditions. With respect to the governing physical parameters, the major aim is to find out under which thermal conditions a so called Thermal Runaway occurs. Therefore, a mathematical electrochemical-thermal model based on the Newman model has been extended with a simple combustion model from reaction kinetics including various types of heat sources assumed to be based on an Arrhenius law. This model was realized in COMSOL Multiphysics modeling software. First simulations were performed for a cylindrical 18650 cell with a L i C o O 2 -cathode to calculate the temperature increase under two simple electric load profiles and to compute critical system parameters. It has been found that the critical cell temperature T crit , above which a thermal runaway may occur is approximately 400 K , which is near the starting temperature of the decomposition of the Solid-Electrolyte-Interface in the anode at 393 . 15 K . Furthermore, it has been found that a thermal runaway can be described in three main stages.

  4. Recovery of Weak Factor Loadings When Adding the Mean Structure in Confirmatory Factor Analysis: A Simulation Study. (United States)

    Ximénez, Carmen


    This article extends previous research on the recovery of weak factor loadings in confirmatory factor analysis (CFA) by exploring the effects of adding the mean structure. This issue has not been examined in previous research. This study is based on the framework of Yung and Bentler (1999) and aims to examine the conditions that affect the recovery of weak factor loadings when the model includes the mean structure, compared to analyzing the covariance structure alone. A simulation study was conducted in which several constraints were defined for one-, two-, and three-factor models. Results show that adding the mean structure improves the recovery of weak factor loadings and reduces the asymptotic variances for the factor loadings, particularly for the models with a smaller number of factors and a small sample size. Therefore, under certain circumstances, modeling the means should be seriously considered for covariance models containing weak factor loadings.

  5. Computer Simulations to Support Science Instruction and Learning: A critical review of the literature (United States)

    Smetana, Lara Kathleen; Bell, Randy L.


    Researchers have explored the effectiveness of computer simulations for supporting science teaching and learning during the past four decades. The purpose of this paper is to provide a comprehensive, critical review of the literature on the impact of computer simulations on science teaching and learning, with the goal of summarizing what is currently known and providing guidance for future research. We report on the outcomes of 61 empirical studies dealing with the efficacy of, and implications for, computer simulations in science instruction. The overall findings suggest that simulations can be as effective, and in many ways more effective, than traditional (i.e. lecture-based, textbook-based and/or physical hands-on) instructional practices in promoting science content knowledge, developing process skills, and facilitating conceptual change. As with any other educational tool, the effectiveness of computer simulations is dependent upon the ways in which they are used. Thus, we outline specific research-based guidelines for best practice. Computer simulations are most effective when they (a) are used as supplements; (b) incorporate high-quality support structures; (c) encourage student reflection; and (d) promote cognitive dissonance. Used appropriately, computer simulations involve students in inquiry-based, authentic science explorations. Additionally, as educational technologies continue to evolve, advantages such as flexibility, safety, and efficiency deserve attention.

  6. Colloid volume loading does not mitigate decreases in central blood volume during simulated hemorrhage while heat stressed

    DEFF Research Database (Denmark)

    Crandall, Craig G; Wilson, Thad E; Marving, Jens


    intravenous colloid volume loading (11 ml/kg). Relative changes in torso and regional blood volumes were determined by gamma camera imaging with technetium-99m labeled erythrocytes. Heat stress reduced blood volume in all regions (ranging from 7 to 16%), while subsequent volume loading returned those values......±5%, all P0.05 relative to heat stress alone). These data suggest that blood volume loading during passive heat stress (via 11 ml/kg of a colloid solution) normalizes regional blood volumes in the torso, but does not mitigate the reduction in central blood volume during a simulated hemorrhagic challenge...

  7. Simulation of Urban Runoff Non-point Source Pollution Load and Analysis on Its Influencing Factors (United States)

    Li, R.; Ruan, X.


    As the point source pollution control has advanced, the proportion of urban non-point pollution caused by rainfall in urban water pollution is increasing. For quantitative evaluation of non-point source pollution in urban rivers and to study their influencing factors, this study takes the inner Qinhuai River in Nanjing as the study area. The non-point source pollution load simulation model of the study area was built based on the Storm Water Management Model (SWMM), and was calibrated using the real-time monitoring data of rainfall and the outlet of the pipes during a short duration rainfall in 2011. TSS, CODMn, TN and TP were selected as the major pollution load indicators to quantitatively assess the rainfall runoff and non-point source pollution of 328.2ha confluence area of inner Qinhuai River, emphatically probe into the variation of the rainfall runoff and non-point source pollution in response to variability in underlying surface and drainage pipes. The results show that: (1) the pollution load concentration in the outlet of the popes increases initially and then decreases, the peak concentration appears at 5~15minutes after the effluent. The concentration of TN and TP appears apparent randomness and fluctuation due to the spatial-temporal uncertainty of the distribution of the non-point source pollution. The maximum flow into the river, the total runoff, the total output of TSS, CODMn, TN and TP during a typical year rainfall in two years return period are 19.67m3/s, 81.74×103m3, 2318.59kg, 1598.08kg, 476.09kg and 24.24kg, respectively. (2)The percentage of impervious underlying surface, the slope of the underlying surface, the percentage of no depression of the impervious underlying surface and the roughness of the pipes, which are the sensitive parameters of the model, have an significant impact on the runoff and pollution load in the outlet of the pipes. Urban rainfall runoff and non-point source pollution can be reduced by reducing the percentage of

  8. A novel modeling to predict the critical current behavior of Nb3Sn PIT strand under transverse load based on a scaling law and Finite Element Analysis

    CERN Document Server

    Wang, Tiening; Takayasu, Makoto; Bordini, Bernardo


    Superconducting Nb3Sn Powder-In-Tube (PIT) strands could be used for the superconducting magnets of the next generation Large Hadron Collider. The strands are cabled into the typical flat Rutherford cable configuration. During the assembly of a magnet and its operation the strands experience not only longitudinal but also transverse load due to the pre-compression applied during the assembly and the Lorentz load felt when the magnets are energized. To properly design the magnets and guarantee their safe operation, mechanical load effects on the strand superconducting properties are studied extensively; particularly, many scaling laws based on tensile load experiments have been established to predict the critical current dependence on strain. However, the dependence of the superconducting properties on transverse load has not been extensively studied so far. One of the reasons is that transverse loading experiments are difficult to conduct due to the small diameter of the strand (about 1 mm) and the data curre...

  9. Dynamic Simulation of the Water-steam System in Once-through Boilers - Sub-critical Power Boiler Case -

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seongil; Choi, Sangmin [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)


    The dynamics of a water-steam system in a once-through boiler was simulated based on the physics-based modeling approach, representing the system in response to large load change or scale disturbance simulations. The modeling considered the mass, energy conservation, and momentum equation in the water pipe and the focus was limited to the sub-critical pressure region. An evaporator tube modeling was validated against the reference data. A simplified boiler system consisting of economizer, evaporator, and superheater was constructed to match a 500 MW power boiler. The dynamic response of the system following a disturbance was discussed along with the quantitative response characteristics. The dynamic response of the boiler system was further evaluated by checking the case of an off-design point operation of the feedwater-to-fuel supply ratio. The results re-emphasized the significance of controlling the feedwater-to-fuel supply ratio and additional design requirements of the water-steam separator and spray attemperator.

  10. Criticality Analysis for Proposed Maximum Fuel Loading in a Standardized SNF Canister with Type 1a Baskets

    Energy Technology Data Exchange (ETDEWEB)

    Chad Pope; Larry L. Taylor; Soon Sam Kim


    This document represents a summary version of the criticality analysis done to support loading SNF in a Type 1a basket/standard canister combination. Specifically, this engineering design file (EDF) captures the information pertinent to the intact condition of four fuel types with different fissile loads and their calculated reactivities. These fuels are then degraded into various configurations inside a canister without the presence of significant moderation. The important aspect of this study is the portrayal of the fuel degradation and its effect on the reactivity of a single canister given the supposition there will be continued moderation exclusion from the canister. Subsequent analyses also investigate the most reactive ‘dry’ canister in a nine canister array inside a hypothetical transport cask, both dry and partial to complete flooding inside the transport cask. The analyses also includes a comparison of the most reactive configuration to other benchmarked fuels using a software package called TSUNAMI, which is part of the SCALE 5.0 suite of software.

  11. Wettability alteration properties of fluorinated silica nanoparticles in liquid-loaded pores: An atomistic simulation (United States)

    Sepehrinia, Kazem; Mohammadi, Aliasghar


    Control over the wettability of reservoir rocks is of crucial importance for enhancing oil and gas recovery. In order to develop chemicals for controlling the wettability of reservoir rocks, we present a study of functionalized silica nanoparticles as candidates for wettability alteration and improved gas recovery applications. In this paper, properties of fluorinated silica nanoparticles were investigated in water or decane-loaded pores of mineral silica using molecular dynamics simulation. Trifluoromethyl groups as water and oil repellents were placed on the nanoparticles. Simulating a pore in the presence of trapped water or decane molecules leads to liquid bridging for both of the liquids. Adsorption of nanoparticles on the pore wall reduces the density of liquid molecules adjacent to the wall. The density of liquid molecules around the nanoparticles decreases significantly with increasing the number of trifluoromethyl groups on the nanoparticles' surfaces. An increased hydrophobicity of the pore wall was observed in the presence of adsorbed fluorinated silica nanoparticles. Also, it is observed that increasing the number of the trifluoromethyl groups results in weakening of liquid bridges. Moreover, the free energy of adsorption on mineral surface was evaluated to be more favorable than that of aggregation of nanoparticles, which suggests nanoparticles adsorb preferably on mineral surface.

  12. Observation and simulation of motion and deformation for impact-loaded metal cylinders (United States)

    Hickman, R. J.; Wise, J. L.; Smith, J. A.; Mersch, J. P.; Robino, C. V.; Arguello, J. G.


    Complementary gas-gun experiments and computational simulations have examined the time-resolved motion and post-mortem deformation of cylindrical metal samples subjected to impact loading. The effect of propagation distance on a compressive waveform generated in a sample by planar impact at one end was determined using a velocity interferometer to track the longitudinal motion at the center of the opposing rear (i.e., free) surface. Samples (25.4-mm diameter) were fabricated from aluminum (types 6061 and 7075), copper (OFHC = oxygen free, high conductivity), stainless steel (type 316), and cobalt alloy L-605 (AMS 5759; also referenced as Haynes®25 alloy). For each material, waveforms obtained for a 25.4-mm long cylinder corresponded to two-dimensional strain at the measurement point. The wave-profile data have been analyzed to (i) establish key dynamic material modeling parameters, (ii) assess the functionality of the Sierra Solid Mechanics-Presto (Sierra/SM) code, and (iii) identify the need for additional testing, material modeling, and/or code development. The results of subsequent simulations have been compared to benchmark recovery experiments that showed the residual plastic deformation incurred by cylinders following end, side, and corner impacts.

  13. Simulation of bioavailable phosphorus and nitrogen loading in an agricultural river basin in Finland using VEMALA v.3 (United States)

    Korppoo, Marie; Huttunen, Markus; Huttunen, Inese; Piirainen, Vanamo; Vehviläinen, Bertel


    The water quality model VEMALA v.3 reconciles the complexity of a freshwater ecosystem model with the terrestrial and marine ecosystem models already implemented in Finland. This model unifies VEMALA-ICECREAM, VEMALA-N and VEMALA 1.1 as it uses their independent terrestrial loading and implements a simplification of the biogeochemical model RIVE and phytoplankton model AQUAPHY in the river network. VEMALA v.3 simulates the transport and transformations of nitrate, ammonium, organic nitrogen, phosphate, particulate inorganic phosphorus, organic phosphorus, phytoplankton, suspended sediments and total organic carbon during their travel to the sea. The model's results were satisfactory in the Aurajoki river basin (South-Western Finland) in simulating nutrients daily loads, with all Nash and Sutcliffe coefficients (NSE) ranging from 0.51 to 0.89 against observations, and monthly loads (NSE = 0.4-0.97 against estimations). Simulations of total nitrogen and total phosphorus loads were comparable to estimated annual loads with the exception of a few exceptional years. The quantification of the nutrient cycling river processes were consistent with the Aurajoki river ecosystem with maximum summer rates for mineralisation 0.1 mgC L-1 d-1 and denitrification 55 mgN m-2 d-1 resulting in a loss of 4% of the annual nitrogen load entering the river. VEMALA v.3 unites the previous versions of VEMALA to better predict the co-impact of dissolved inorganic nitrogen and phosphate on algal growth and therefore eutrophication. Simulation of bioavailable nutrients rather than total nutrients will allow the distinction in the quality of the various loading sources, farming actions and loading reduction actions. In the Aurajoki simulation, nitrate and ammonium represented on average 74% and 3% respectively of the total nitrogen load to the Baltic Sea, while phosphate constituted 38% of the total phosphorus load to the sea. Thus, the biological impact in the river and the sea will be better

  14. Simulation-based crisis resource management training for pediatric critical care medicine: a review for instructors. (United States)

    Cheng, Adam; Donoghue, Aaron; Gilfoyle, Elaine; Eppich, Walter


    To review the essential elements of crisis resource management and provide a resource for instructors by describing how to use simulation-based training to teach crisis resource management principles in pediatric acute care contexts. A MEDLINE-based literature source. OUTLINE OF REVIEW: This review is divided into three main sections: Background, Principles of Crisis Resource Management, and Tools and Resources. The background section provides the brief history and definition of crisis resource management. The next section describes all the essential elements of crisis resource management, including leadership and followership, communication, teamwork, resource use, and situational awareness. This is followed by a review of evidence supporting the use of simulation-based crisis resource management training in health care. The last section provides the resources necessary to develop crisis resource management training using a simulation-based approach. This includes a description of how to design pediatric simulation scenarios, how to effectively debrief, and a list of potential assessment tools that instructors can use to evaluate crisis resource management performance during simulation-based training. Crisis resource management principles form the foundation for efficient team functioning and subsequent error reduction in high-stakes environments such as acute care pediatrics. Effective instructor training is required for those programs wishing to teach these principles using simulation-based learning. Dissemination and integration of these principles into pediatric critical care practice has the potential for a tremendous impact on patient safety and outcomes.

  15. An FMM-FFT Accelerated SIE Simulator for Analyzing EM Wave Propagation in Mine Environments Loaded with Conductors

    KAUST Repository

    Yucel, Abdulkadir C.


    A fast and memory efficient 3D full wave simulator for analyzing electromagnetic (EM) wave propagation in electrically large and realistic mine tunnels/galleries loaded with conductors is proposed. The simulator relies on Muller and combined field surface integral equations (SIEs) to account for scattering from mine walls and conductors, respectively. During the iterative solution of the system of SIEs, the simulator uses a fast multipole method - fast Fourier transform (FMM-FFT) scheme to reduce CPU and memory requirements. The memory requirement is further reduced by compressing large data structures via singular value and Tucker decompositions. The efficiency, accuracy, and real-world applicability of the simulator are demonstrated through characterization of EM wave propagation in electrically large mine tunnels/galleries loaded with conducting cables and mine carts.

  16. Integrating of scenario-based simulation into radiology education to improve critical thinking skills

    Directory of Open Access Journals (Sweden)

    Abuzaid MM


    Full Text Available MM Abuzaid, W Elshami Medical Diagnostic Imaging Department, College of Health Sciences, University of Sharjah, Sharjah, United Arab Emirates Introduction: For many years, conventional radiographic films have been used for radiology education. Nevertheless, advances in imaging modalities, image quality, and the number of images produced by various methods have seen a move toward digital formats. Certainly, a patient’s case has a significant value in medical education; it can transfer theoretical knowledge to real experiences. The aim of this study is to evaluate the value of scenario-based simulations in radiology education and their impact on professional learning outcomes.Materials and methods: Patient scenarios were collected and converted to digital teaching files, each supported by clinical history, anatomy illustration, as well as medical and radiological investigation. The scenarios were presented online to radiology professionals for 6 months. At the end of the study, the scenarios were evaluated regarding design, content, and their role in improving critical thinking.Results: Twenty-two scenarios were published online covering various radiology areas. Two hundred and thirty-eight radiology professionals were invited, and 84% participated in the evaluation process. Each participant completed an average of 13 scenarios with an approximate time of 23 minutes for each. The majority of participants agreed or strongly agreed that the scenarios were well designed (94%, were appropriate to their level of knowledge (70%, and helped them in critical thinking and in understanding similar cases (79%. Conclusion: The integration of scenario-based simulations in radiology education led to a positive impact on learning outcomes, formative interactive learning, and filling the gap between theory and practice. Moreover, it promoted critical thinking skills and allowed radiology professionals to demonstrate their knowledge of similar cases

  17. Heart rate, anxiety and performance of residents during a simulated critical clinical encounter: a pilot study. (United States)

    Clarke, Samuel; Horeczko, Timothy; Cotton, Dale; Bair, Aaron


    High-fidelity patient simulation has been praised for its ability to recreate lifelike training conditions. The degree to which high fidelity simulation elicits acute emotional and physiologic stress among participants - and the influence of acute stress on clinical performance in the simulation setting - remain areas of active exploration. We examined the relationship between residents' self-reported anxiety and a proxy of physiologic stress (heart rate) as well as their clinical performance in a simulation exam using a validated assessment of non-technical skills, the Ottawa Crisis Resource Management Global Rating Scale (Ottawa GRS). This was a prospective observational cohort study of emergency medicine residents at a single academic center. Participants managed a simulated clinical encounter. Anxiety was assessed using a pre- and post-simulation survey, and continuous cardiac monitoring was performed on each participant during the scenario. Performance in the simulation scenario was graded by faculty raters using a critical actions checklist and the Ottawa GRS instrument. Data collection occurred during the 2011 academic year. Of 40 eligible residents, 34 were included in the analysis. The median baseline heart rate for participants was 70 beats per minute (IQR: 62 - 78). During the simulation, the median maximum heart rate was 140 beats per minute (IQR: 137 - 151). The median minimum heart rate during simulation was 81 beats per minute (IQR: 72 - 92), and mean heart rate was 117 beats per minute (95% CI: 111 - 123). Pre- and post-simulation anxiety scores were equal (mean 3.3, IQR: 3 to 4). The minimum and maximum Overall Ottawa GRS scores were 2.33 and 6.67, respectively. The median Overall score was 5.63 (IQR: 5.0 to 6.0). Of the candidate predictors of Overall performance in a multivariate logistic regression model, only PGY status showed statistical significance (P = 0.02). Simulation is associated with physiologic stress, and heart rate elevation alone

  18. Modeling of the Critical-Current Behavior of Nb3Sn Subsized Cables Under Transverse Load Using 2D Finite Element Analysis and a Strain Scaling Law

    CERN Document Server

    Wang, T; Takayasu, M; Bordini, B


    The mechanisms causing the critical-current degradation of ITER-type Nb3Sn Cable-in-Conduit-Conductors have been studied in the past decade. One of the origins of the degradation of the performance is the Lorentz load during magnet operations. The strands within the cable subjected to the transverse loads locally experience larger strains than the ones caused by tensile loads. Results obtained with experiments on full size cables are limited due to their cost and difficulty so, to predict the degradations of a Nb3Sn CICC under transverse loads, empirical laws should be established. Strain scaling laws are available but have never been used to determine the behavior of strands under transverse load. We propose a new method, by which the critical-current behavior of a subsized cable under transverse loads is derived from the critical-current behavior under uni-axial strains. This method is based on the strain state of the Nb3Sn filaments obtained by finite element analysis (FEA). The FEA strain results are used...

  19. Simulation of a current source with a Cole-Cole load for multi-frequency electrical impedance tomography. (United States)

    Aguiar Santos, Susana; Schlebusch, Thomas; Leonhardt, Steffen


    An accurate current source is one of the keys in the hardware of Electrical impedance Tomography systems. Limitations appear mainly at higher frequencies and for non-simple resistive loads. In this paper, we simulate an improved Howland current source with a Cole-Cole load. Simulations comparing two different op-amps (THS4021 and OPA843) were performed at 1 kHz to 1 MHz. Results show that the THS4021 performed better than the OPA843. The current source with THS4021 reaches an output impedance of 20 MΩ at 1 kHz and above 320 kΩ at 1 MHz, it provides a constant and stable output current up to 4 mA, in the complete range of frequencies, and for Cole-Cole (resistive and capacitive) load.

  20. Fuel loads and simulated fire behavior in "old-stage" beetle-infested ponderosa pine of the Colorado Plateau (United States)

    E. Matthew Hansen; Morris C. Johnson; Barbara J. Bentz; James C. Vandygriff; A. Steven. Munson


    Recent bark beetle outbreaks in western North America have led to concerns regarding changes in fuel profiles and associated changes in fire behavior. Data are lacking for a range of infestation severities and time since outbreak, especially for relatively arid cover types. We surveyed fuel loads and simulated fire behavior for ponderosa pine stands of the...

  1. New graduate nurses' perceptions of the effects of clinical simulation on their critical thinking, learning, and confidence. (United States)

    Kaddoura, Mahmoud A


    Critical thinking has been a crucial outcome of nursing educational programs. Effective nurses should be knowledgeable about complex patient situations and confident in their skills. One teaching strategy recently adopted by some educators to develop nurses' critical thinking, learning, and confidence is simulation. Simulation incorporates scenarios and case studies developed to replicate real-life clinical situations. Learners are asked to solve clinical problems and make critical decisions based on the information provided. Little research has been done on how simulation experiences promote critical thinking, learning, and confidence, especially in new graduate nurses. This study explored the perceptions of new graduate nurses of how clinical simulation developed their critical thinking skills, learning, and confidence throughout their hospital clinical training. Ten new baccalaureate nursing graduates voluntarily participated in this study, which used an exploratory descriptive design. Data were collected by demographic questionnaires and semi-structured interviews and were analyzed using content analysis. Participants reported that simulation prepared them well to care confidently for critically ill patients. Simulation also helped them learn to make sound clinical decisions to improve patient outcomes. The findings have crucial implications for nursing education, practice, and research. They provide evidence to support the use of simulation as a teaching strategy to promote critical thinking skills, learning, and confidence. Copyright 2010, SLACK Incorporated.

  2. Critical Evaluation of the ISCCP Simulator Using Ground-Based Remote Sensing Data

    Energy Technology Data Exchange (ETDEWEB)

    Mace, G G; Houser, S; Benson, S; Klein, S A; Min, Q


    Given the known shortcomings in representing clouds in Global Climate Models (GCM) comparisons with observations are critical. The International Satellite Cloud Climatology Project (ISCCP) diagnostic products provide global descriptions of cloud top pressure and column optical depth that extends over multiple decades. The necessary limitations of the ISCCP retrieval algorithm require that before comparisons can be made between model output and ISCCP results the model output must be modified to simulate what ISCCP would diagnose under the simulated circumstances. We evaluate one component of the so-called ISCCP simulator in this study by comparing ISCCP and a similar algorithm with various long-term statistics derived from the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) Climate Research Facility ground-based remote sensors. We find that were a model to simulate the cloud radiative profile with the same accuracy as can be derived from the ARM data, then the likelihood of that occurrence being placed in the same cloud top pressure and optical depth bin as ISCCP of the 9 bins that have become standard ranges from 30% to 70% depending on optical depth. While the ISCCP simulator improved the agreement of cloud-top pressure between ground-based remote sensors and satellite observations, we find minor discrepancies due to the parameterization of cloud top pressure in the ISCCP simulator. The primary source of error seems to be related to discrepancies in visible optical depth that are not accounted for in the ISCCP simulator. We show that the optical depth discrepancies are largest when the assumptions necessary for plane parallel radiative transfer optical depths retrievals are violated.

  3. Tests of an alternating current propulsion subsystem for electric vehicles on a road load simulator (United States)

    Stenger, F. J.


    The test results of a breadboard version of an ac electric-vehicle propulsion subsystem are presented. The breadboard was installed in the NASA Lewis Research Center Road Load Simulator facility and tested under steady-state and transient conditions. Steady-state tests were run to characterize the system and component efficiencies over the complete speed-torque range within the capability of the propulsion subsystem in the motoring mode of operation. Transient tests were performed to determine the energy consumption of the breadboard over the acceleration and cruise portions of SAE J227 and driving schedules B, C, and D. Tests in the regenerative mode were limited to the low-gear-speed range of the two speed transaxle used in the subsystem. The maximum steady-state subsystem efficiency observed for the breadboard was 81.5 percent in the high-gear-speed range in the motoring mode, and 76 percent in the regenerative braking mode (low gear). The subsystem energy efficiency during the transient tests ranged from 49.2 percent for schedule B to 68.4 percent for Schedule D.

  4. On the Critical Behaviour of Observed and Simulated Spatial Soil Moisture Fields during SGP97

    Directory of Open Access Journals (Sweden)

    Mekonnen Gebremichael


    Full Text Available The aircraft-based ESTAR soil moisture fields from the Southern Great Plains 1997 (SGP97 Hydrology Experiment are compared to the simulated ones obtained by Bertoldi et al. [1] with the GEOtop model [2], with a particular focus on their capability in capturing the critical point behaviour in their space-time dynamics (see [3]. The critical point behaviour should denote the transition of soil moisture spatial patterns from an unorganized to organized appearance, as conditions become wetter. The study region is the Little Washita watershed, located in the southwest Oklahoma, in the Southern Great Plains region of the USA. The case study takes place from June 27 to July 16 and encompasses wetting and drying cycles allowing for exploring the behaviour under transient conditions. Results show that the critical probability value is 0.85 for GEOtop, and 0.80 for ESTAR. The GEOtop patterns appear more fragmented, being more reluctant to organization, as confirmed by the higher value of critical probability. Such behaviour is probably inherited by the model’s parameterization: land use and soil classes impose additional spatial structures to those related to the meteorological forcings and the hillslope morphology, driving to higher degrees of heterogeneity.

  5. Managing the complexity of critical infrastructures a modelling and simulation approach

    CERN Document Server

    Rosato, Vittorio; Kyriakides, Elias; Rome, Erich


    This book is open access under a CC BY 4.0 license. This book summarizes work being pursued in the context of the CIPRNet (Critical Infrastructure Preparedness and Resilience Research Network) research project, co-funded by the European Union under the Seventh Framework Programme (FP7). The project is intended to provide concrete and on-going support to the Critical Infrastructure Protection (CIP) research communities, enhancing their preparedness for CI-related emergencies, while also providing expertise and technologies for other stakeholders to promote their understanding and mitigation of the consequences of CI disruptions, leading to enhanced resilience. The book collects the tutorial material developed by the authors for several courses on the modelling, simulation and analysis of CIs, representing extensive and integrated CIP expertise. It will help CI stakeholders, CI operators and civil protection authorities understand the complex system of CIs, and help them adapt to these changes and threats in or...

  6. A longitudinal interprofessional simulation curriculum for critical care teams: Exploring successes and challenges. (United States)

    Leclair, Laurie W; Dawson, Mary; Howe, Alison; Hale, Sue; Zelman, Eric; Clouser, Ryan; Garrison, Garth; Allen, Gilman


    Interprofessional care teams are the backbone of intensive care units (ICUs) where severity of illness is high and care requires varied skills and experience. Despite this care model, longitudinal educational programmes for such workplace teams rarely include all professions. In this article, we report findings on the initial assessment and evaluation of an ongoing, longitudinal simulation-based curriculum for interprofessional workplace critical care teams. The study had two independent components, quantitative learner assessment and qualitative curricular evaluation. To assess curriculum effectiveness at meeting learning objectives, participant-reported key learning points identified using a self-assessment tool administered immediately following curricular participation were mapped to session learning objectives. To evaluate the curriculum, we conducted a qualitative study using a phenomenology approach involving purposeful sampling of nine curricular participants undergoing recorded semi-structured interviews. Verbatim transcripts were reviewed by two independent readers to derive themes further subdivided into successes and barriers. Learner self-assessment demonstrated that the majority of learners, across all professions, achieved at least one intended learning objective with senior learners more likely to report team-based objectives and junior learners more likely to report knowledge/practice objectives. Successes identified by curricular evaluation included authentic critical care curricular content, safe learning environment, and team comradery from shared experience. Barriers included unfamiliarity with the simulation environment and clinical coverage for curricular participation. This study suggests that a sustainable interprofessional curriculum for workplace ICU critical care teams can achieve the desired educational impact and effectively deliver authentic simulated work experiences if barriers to educational engagement and participation can be

  7. A comparison of educational strategies for the acquisition of nursing student?s performance and critical thinking: simulation-based training vs. integrated training (simulation and critical thinking strategies)


    Zarifsanaiey, Nahid; Amini, Mitra; Saadat, Farideh


    Abstract Background There is a need to change the focus of nursing education from traditional teacher-centered training programs to student-centered active methods. The integration of the two active learning techniques will improve the effectiveness of training programs. The objective of this study is to compare the effects of the integrated training (simulation and critical thinking strategies) and simulation-based training on the performance level and critical thinking ability of nursing st...

  8. Simulation study of the ionizing front in the critical ionization velocity phenomenon (United States)

    Machida, S.; Goertz, C. K.; Lu, G.


    The simulation of the critical ionization velocity for a neutral gas cloud moving across the static magnetic field is presented. A low-beta plasma is studied, using a two and a half-dimensional electrostatic code linked with the Plasma and Neutral Interaction Code (Goertz and Machida, 1987). The physics of the ionizing front and the instabilities which occur there are discussed. Results are presented from four numerical runs designed so that the effects of the charge separation field can be distinguished from the wave heating.

  9. Clustering and traveling waves in the Monte Carlo criticality simulation of decoupled and confined media

    Directory of Open Access Journals (Sweden)

    Eric Dumonteil


    Full Text Available The Monte Carlo criticality simulation of decoupled systems, as for instance in large reactor cores, has been a challenging issue for a long time. In particular, due to limited computer time resources, the number of neutrons simulated per generation is still many order of magnitudes below realistic statistics, even during the start-up phases of reactors. This limited number of neutrons triggers a strong clustering effect of the neutron population that affects Monte Carlo tallies. Below a certain threshold, not only is the variance affected but also the estimation of the eigenvectors. In this paper we will build a time-dependent diffusion equation that takes into account both spatial correlations and population control (fixed number of neutrons along generations. We will show that its solution obeys a traveling wave dynamic, and we will discuss the mechanism that explains this biasing of local tallies whenever leakage boundary conditions are applied to the system.

  10. Simulation-based multidisciplinary team training decreases time to critical operations for trauma patients. (United States)

    Murphy, Margaret; Curtis, Kate; Lam, Mary K; Palmer, Cameron S; Hsu, Jeremy; McCloughen, Andrea


    Simulation has been promoted as a platform for training trauma teams. However, it is not clear if this training has an impact on health service delivery and patient outcomes. This study evaluates the association between implementation of a simulation based multidisciplinary trauma team training program at a metropolitan trauma centre and subsequent patient outcomes. This was a retrospective review of trauma registry data collected at an 850-bed Level 1 Adult Trauma Centre in Sydney, Australia. Two concurrent four-year periods, before and after implementation of a simulation based multidisciplinary trauma team training program were compared for differences in time to critical operations, Emergency Department (ED) length of stay (LOS) and patient mortality. There were 2389 major trauma patients admitted to the hospital during the study, 1116 in the four years preceding trauma team training (the PREgroup) and 1273 in the subsequent 4 years (the POST group). There were no differences between the groups with respect to gender, body region injured, incidence of polytrauma, and pattern of arrival to ED. The POST group was older (median age 54 versus 43 years, p team training was associated with a reduction in time to critical operation while overall ED length of stay increased. Simulation is promoted as a platform for training teams; but the complexity of trauma care challenges efforts to demonstrate direct links between multidisciplinary team training and improved outcomes. There remain considerable gaps in knowledge as to how team training impacts health service delivery and patient outcomes. Retrospective comparative therapeutic/care management study, Level III evidence. Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.

  11. Dynamic Response of Cable-Supported Façades Subjected to High-Level Air Blast Loads: Numerical Simulations and Mitigation Techniques

    Directory of Open Access Journals (Sweden)

    Claudio Amadio


    Full Text Available A glazing façade subjected to blast loads has a structural behaviour that strongly differs from the typical response of a glazing system subjected to ordinary loads. Consequently, sophisticated modelling techniques are required to identify correctly its criticalities. The paper investigates the behaviour of a cable-supported façade subjected to high-level blast loading. Nonlinear dynamic analyses are performed in ABAQUS/Explicit using a sophisticated FE-model (M01, calibrated to dynamic experimental and numerical results. The structural effects of the total design blast impulse, as well as only its positive phase, are analyzed. At the same time, the possible cracking of glass panels is taken into account, since this phenomenon could modify the response of the entire façade. Finally, deep investigations are dedicated to the bearing cables, since subjecting them to elevated axial forces and their collapse could compromise the integrity of the cladding wall. Based on results of previous studies, frictional devices differently applied at their ends are presented to improve the response of the façade under the impact of a high-level explosion. Structural effects of various solutions are highlighted through dynamic simulations. Single vertical devices, if appropriately calibrated, allow reducing significantly the axial forces in cables, and lightly the tensile stresses in glass panes.

  12. Psychomotor skills and cognitive load training on a virtual reality laparoscopic simulator for tubal surgery is effective. (United States)

    Bharathan, Rasiah; Vali, Saaliha; Setchell, Thomas; Miskry, Tariq; Darzi, Ara; Aggarwal, Rajesh


    Validation of a virtual reality (VR) simulator for the training and assessment of laparoscopic tubal surgery and mapping of cognitive load. Prospective cohort study conducted at the Imperial College Virtual Reality Surgical Skills laboratory amongst 25 trainees and nine senior gynaecologists. Participants performed two sessions of salpingectomy and salpingotomy procedures on a VR simulator to assess construct validity. Nine novices performed ten such sessions to enable assessment of the learning curve. The relationship between cognitive load and the dexterity parameters was assessed. Simulator fidelity was reported by experienced and intermediate level gynaecologists. Statistical analyses utilised non-parametric tests, Kruskall-Wallis and Mann-Whitney U tests. Learning curves were assessed using the Friedman test and Wilcoxon Signed Ranks test. Relationship between dexterity metrics and cognitive load was performed using Spearman's rank order correlation. Salpingectomy demonstrated construct validity for time taken by experienced, intermediate and novice gynaecologists (median 170 vs. 191 vs. 313s (P=0.003) respectively) and movements (median 200 vs. 267 vs. 376s, P=0.045). Salpingotomy demonstrated construct validity for time taken (median 183 vs. 191 vs. 306s, P=<0.001) and movements (median 210 vs. 233 vs. 328s, P=0.005). Learning curve analysis for salpingectomy displayed a plateau for time taken after the eighth session, and the fourth session for movements. Salpingotomy displayed a plateau after the eighth session for both time taken and movements. Cognitive load correlated significantly with dexterity parameters. The fidelity scores were not significantly different between the two procedures (P=0.619). The LAP Mentor VR laparoscopic simulator is a valid and effective tool for training novice surgeons in ectopic pregnancy surgery. Reduction in cognitive load significantly correlates with the learning curves. Copyright © 2013 Elsevier Ireland Ltd. All rights

  13. Critical Loads of Acid Deposition for Wilderness Lakes in the Sierra Nevada (California) Estimated by the Steady-State Water Chemistry Model (United States)

    Glenn D. Shaw; Ricardo Cisneros; Donald Schweizer; James O. Sickman; Mark E. Fenn


    Major ion chemistry (2000-2009) from 208 lakes (342 sample dates and 600 samples) in class I and II wilderness areas of the Sierra Nevada was used in the Steady-State Water Chemistry (SSWC) model to estimate critical loads for acid deposition and investigate the current vulnerability of high elevation lakes to acid deposition. The majority of the lakes were dilute (...

  14. The effect of simulation courseware on critical thinking in undergraduate nursing students: multi-site pre-post study. (United States)

    Shin, Hyunsook; Ma, Hyunhee; Park, Jiyoung; Ji, Eun Sun; Kim, Dong Hee


    The use of simulations has been considered as opportunities for students to enhance their critical thinking (CT), but previous studies were limited because they did not provide in-depth information on the working dynamics of simulation or on the effects of the number of simulation exposures on CT. This study examined the effect of an integrated pediatric nursing simulation used in a nursing practicum on students' CT abilities and identified the effects of differing numbers of simulation exposures on CT in a multi-site environment. The study used a multi-site, pre-test, post-test design. A total of 237 nursing students at three universities enrolled in a pediatric practicum participated in this study from February to December 2013. All three schools used the same simulation courseware, including the same simulation scenarios, evaluation tools, and simulation equipment. The courseware incorporated high-fidelity simulators and standardized patients. Students at school A completed one simulation session, whereas students at schools B and C completed two and three simulation sessions, respectively. Yoon's Critical Thinking Disposition tool (2008) was used to measure students' CT abilities. The gains in students' CT scores varied according to their numbers of exposures to the simulation courseware. With a single exposure, there were no statistically significant gains in CT, whereas three exposures to the courseware produced significant gains in CT. In seven subcategories of critical thinking, three exposures to the simulation courseware produced CT gains in the prudence and intellectual eagerness subcategories, and the overall simulation experience produced CT gains in the prudence, systematicity, healthy skepticism, and intellectual eagerness subcategories. Simulation courseware may produce positive learning outcomes for prudence in nursing education. In addition, the findings from the multi-site comparative study may contribute to greater understanding of how patient

  15. Relationship between Fidelity and Dose of Human Patient Simulation, Critical Thinking Skills, and Knowledge in an Associate Degree Nursing Program (United States)

    Beebe, Rosella I.


    This study examined the relationship between human patient simulation (HPS), critical thinking skills, and knowledge acquisition after HPS was integrated across the curriculum of an associate degree nursing program to determine if differences existed in critical thinking and knowledge of students based on the fidelity of HPS used and amount of…

  16. Comparison of Simulation-Based Performance with Metrics of Critical Thinking Skills in Nursing Students: A Pilot Study (United States)

    Fero, Laura J.


    Alternative approaches to evaluating critical thinking skills are needed, as pencil and paper assessments may not accurately predict simulated or actual clinical performance. To ensure patient safety, it is imperative to determine how to best promote and measure critical thinking skills. Few studies have examined how these skills are related to…

  17. The Effects of Moderate- and High-Fidelity Patient Simulator Use on Critical Thinking in Associate Degree Nursing Students (United States)

    Vieck, Jana


    The purpose of this study was to examine the impact of moderate- and high-fidelity patient simulator use on the critical thinking skills of associate degree nursing students. This quantitative study used a quasi-experimental design and the Health Sciences Reasoning Test (HSRT) to evaluate the critical thinking skills of third semester nursing…

  18. Simulation-based assessment to identify critical gaps in safe anesthesia resident performance. (United States)

    Blum, Richard H; Boulet, John R; Cooper, Jeffrey B; Muret-Wagstaff, Sharon L


    Valid methods are needed to identify anesthesia resident performance gaps early in training. However, many assessment tools in medicine have not been properly validated. The authors designed and tested use of a behaviorally anchored scale, as part of a multiscenario simulation-based assessment system, to identify high- and low-performing residents with regard to domains of greatest concern to expert anesthesiology faculty. An expert faculty panel derived five key behavioral domains of interest by using a Delphi process (1) Synthesizes information to formulate a clear anesthetic plan; (2) Implements a plan based on changing conditions; (3) Demonstrates effective interpersonal and communication skills with patients and staff; (4) Identifies ways to improve performance; and (5) Recognizes own limits. Seven simulation scenarios spanning pre-to-postoperative encounters were used to assess performances of 22 first-year residents and 8 fellows from two institutions. Two of 10 trained faculty raters blinded to trainee program and training level scored each performance independently by using a behaviorally anchored rating scale. Residents, fellows, facilitators, and raters completed surveys. Evidence supporting the reliability and validity of the assessment scores was procured, including a high generalizability coefficient (ρ = 0.81) and expected performance differences between first-year resident and fellow participants. A majority of trainees, facilitators, and raters judged the assessment to be useful, realistic, and representative of critical skills required for safe practice. The study provides initial evidence to support the validity of a simulation-based performance assessment system for identifying critical gaps in safe anesthesia resident performance early in training.

  19. Fusing Simulation Results From Multifidelity Aero-servo-elastic Simulators - Application To Extreme Loads On Wind Turbine

    DEFF Research Database (Denmark)

    Abdallah, Imad; Sudret, Bruno; Lataniotis, Christos


    Fusing predictions from multiple simulators in the early stages of the conceptual design of a wind turbine results in reduction in model uncertainty and risk mitigation. Aero-servo-elastic is a term that refers to the coupling of wind inflow, aerodynamics, structural dynamics and controls. Fusing...... the response data from multiple aero-servo-elastic simulators could provide better predictive ability than using any single simulator. The co-Kriging approach to fuse information from multifidelity aero-servo-elastic simulators is presented. We illustrate the co-Kriging approach to fuse the extreme flapwise...

  20. Synthesis of recent advances in critical loads research on impacts from atmospheric nitrogen deposition on terrestrial plant communities. (United States)

    Clark, C.; Horn, K. J.; Thomas, R. Q.; Simkin, S.; Pardo, L. H.; Blett, T.; Lawrence, G. B.; Belyazid, S.; Phelan, J.


    Nitrogen (N) deposition is one of the primary threats to plant biodiversity world-wide after habitat destruction and climate change. As a primary limiting nutrient and contributor to soil acidification, N inputs have the capacity to alter ecosystems through several mechanisms. Up until now, there was very little detailed information on the impacts from this stressor at the species level, or how climate and edaphic factors could alter ecosystem sensitivity. Here we summarize and synthesize four major efforts, funded by EPA, USGS, USFS, and the NPS, which greatly advance our understanding of this stressor. These include (1) a national analysis of sensitivity to N deposition for 114 tree species, (2) a national analysis of impacts from N deposition on herbaceous species and how climate and soil factors modify that sensitivity, (3) a regional dynamic modeling study of impacts and recovery from N and S deposition for a dominant northeastern forest type under a range of future climate and deposition scenarios, and (4) a large assessment of impacts to streams, soils, and vegetation along the 2000+ mile stretch of the Appalachian Trail. Here we show many responses to this stressor for all taxonomic groups, with some species decreasing, some increasing, and some unaffected by N deposition. However, dozens of tree and herb species are negatively affected and are of particular concern for conservation purposes, with vulnerability being greatly affected by regional climate and local edaphic factors. Dynamic modeling suggests that, at least in some northeastern forests, recovery across a broad range of climate change and management scenarios is unlikely by 2100. The study along the Appalachian Trail, a beloved national recreation trail, echoes these findings, with stream, soils, and vegetation impacted across large percentages of sites, and only moderate capacity for recovery by 2100. In total, this work highlights several recent advances in the area of critical loads research

  1. Effect of simulation training on the development of nurses and nursing students' critical thinking: A systematic literature review. (United States)

    Adib-Hajbaghery, Mohsen; Sharifi, Najmeh


    To gain insight into the existing scientific evidence on the effect of simulation on critical thinking in nursing education. A systematic literature review of original research publications. In this systematic review, the papers published in English and Farsi databases of PubMed, Science Direct, ProQuest, ERIC, Google Scholar and Ovid, MagIran and SID, from 1975 to 2015 were reviewed by two independent researchers. Original research publications were eligible for review when they described simulation program directed on nursing student and nurses; used a control group or a pretest post-test design; and gave information about the effects of simulation on critical thinking. Two reviewers independently assessed the studies for inclusion. Methodological quality of the included studies was also independently assessed by the reviewers, using a checklist developed by Greenhalgh et al. and the checklist of Cochrane Center. Data related to the original publications were extracted by one reviewer and checked by a second reviewer. No statistical pooling of outcomes was performed, due to the large heterogeneity of outcomes. After screening the titles and abstracts of 787 papers, 16 ones were included in the review according to the inclusion criteria. These used experimental or quasi-experimental designs. The studies used a variety of instruments and a wide range of simulation methods with differences in duration and numbers of exposures to simulation. Eight of the studies reported that simulation training positively affected the critical thinking skills. However, eight studies reported ineffectiveness of simulation on critical thinking. Studies are conflicting about the effect of simulation on nurses and nursing students' critical thinking. Also, a large heterogeneity exists between the studies in terms of the instruments and the methods used. Thus, more studies with careful designs are needed to produce more credible evidence on the effectiveness of simulation on critical

  2. Simulation of Nitrogen and Phosphorus Load Runoff by a GIS-based Distributed Model for Chikugo River Watershed (United States)

    Iseri, Haruka; Hiramatsu, Kazuaki; Harada, Masayoshi

    A distributed model was developed in order to simulate the process of nitrogen and phosphorus load runoff in the semi-urban watershed of the Chikugo River, Japan. A grid of cells 1km in size was laid over the study area, and several input variables for each cell area including DEM, land use and statistical data were extracted by GIS. In the process of water runoff, hydrograph calculated at Chikugo Barrage was in close agreement with the observed one, which achieved Nash-Sutcliffe coefficient of 0.90. In addition, the model simulated reasonably well the movement of TN and TP at each station. The model was also used to analyze three scenarios based on the watershed management: (1) reduction of nutrient loads from livestock farm, (2) improvement of septic tanks' wastewater treatment system and (3) application of purification function of paddy fields. As a result, effectiveness of management strategy in each scenario depended on land use patterns. The reduction rates of nutrient load effluent in scenarios (1) and (3) were higher than that in scenario (2). The present result suggests that an appropriate management of livestock farm together with the effective use of paddy environment would have significant effects on the reduction of nutrient loads. A suitable management strategy should be planned based on the land use pattern in the watershed.

  3. The impact of acid deposition and forest harvesting on lakes and their forested catchments in south central Ontario: a critical loads approach

    Directory of Open Access Journals (Sweden)

    S. A. Watmough


    Full Text Available The impact of acid deposition and tree harvesting on three lakes and their representative sub-catchments in the Muskoka-Haliburton region of south-central Ontario was assessed using a critical loads approach. As nitrogen dynamics in forest soils are complex and poorly understood, for simplicity and to allow comparison among lakes and their catchments, CLs (A for both lakes and forest soils were calculated assuming that nitrate leaching from catchments will not change over time (i.e. a best case scenario. In addition, because soils in the region are shallow, base cation weathering rates for the representative sub-catchments were calculated for the entire soil profile and these estimates were also used to calculate critical loads for the lakes. These results were compared with critical loads obtained by the Steady State Water Chemistry (SSWC model. Using the SSWC model, critical loads for lakes were between 7 and 19 meq m-2yr-1 higher than those obtained from soil measurements. Lakes and forests are much more sensitive to acid deposition if forests are harvested, but two acid-sensitive lakes had much lower critical loads than their respective forested sub-catchments implying that acceptable acid deposition levels should be dictated by the most acid-sensitive lakes in the region. Under conditions that assume harvesting, the CL (A is exceeded at two of the three lakes and five of the six sub-catchments assessed in this study. However, sulphate export from catchments greatly exceeds input in bulk deposition and, to prevent lakes from falling below the critical chemical limit, sulphate inputs to lakes must be reduced by between 37% and 92% if forests are harvested. Similarly, sulphate leaching from forested catchments that are harvested must be reduced by between 16 and 79% to prevent the ANC of water draining the rooting zone from falling below 0 μeq l-1. These calculations assume that extremely low calcium leaching losses (9–27 μeq l-1 from

  4. Evaluation of Hydraulic Loads on the Runner Blades of a Kaplan Turbine using CFD Simulation and Model Test

    Directory of Open Access Journals (Sweden)

    Zoltan-Iosif Korka


    Full Text Available CFD (Computational Fluid Dynamic is today a standard procedure for analyzing and simulating the flow through several hydraulic machines. In this process, the fluid flow domain is divided into small volumes where the governing equations are converted into algebraic ones, which are numerically solved. Computational results strongly depend on the applied mathematical model and on the numerical methods used for converting the governing equations into the algebraic ones. The goal of the paper is to evaluate, by numerical simulation, the hydraulic loads (forces and torques on the runner blades of an existent Kaplan turbine and to compare them with the experimental results obtained from model test.

  5. Critical material attributes (CMAs) of strip films loaded with poorly water-soluble drug nanoparticles: III. Impact of drug nanoparticle loading. (United States)

    Krull, Scott M; Moreno, Jacqueline; Li, Meng; Bilgili, Ecevit; Davé, Rajesh N


    Polymer strip films have emerged as a robust platform for poorly water-soluble drug delivery. However, the common conception is that films cannot exceed low drug loadings, mainly due to poor drug stability, slow release, and film brittleness. This study explores the ability to achieve high loadings of poorly water-soluble drug nanoparticles in strip films while retaining good mechanical properties and enhanced dissolution rate. Aqueous suspensions containing up to 30wt% griseofulvin nanoparticles were prepared via wet stirred media milling and incorporated into hydroxypropyl methylcellulose (HPMC) films. Griseofulvin loading in films was adjusted to be between 9 and 49wt% in HPMC-E15 films and 30 and 73wt% in HPMC-E4M films by varying the mixing ratio of HPMC solution-to-griseofulvin suspension. All films exhibited good content uniformity and nanoparticle redispersibility up to 50wt% griseofulvin, while E4M films above 50wt% griseofulvin had slightly worse content uniformity and poor nanoparticle redispersibility. Increasing drug loading in films generally required more time to achieve 100% release during dissolution, although polymer-drug clusters dispersed from E4M films above 50wt% griseofulvin, resulting in similar dissolution profiles. While all films exhibited good tensile strength, a significant decrease in percent elongation was observed above 40-50wt% GF, resulting in brittle films. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. The simulated clinical environment as a platform for refining critical thinking in nursing students: a pilot program. (United States)

    Wane, Daryle; Lotz, Karen


    This research explores the use of clinical simulations as a platform for stimulating critical thinking in nursing students. This study takes place in an associate degree nursing program with a clinical group of nursing students. Utilizing a faculty partnership approach, information was presented to the clinical group. Students were divided into small groups to create simulation scenarios. Students were able to appreciate complexity of care and research differential diagnoses as they applied to care and management of changes in client condition scenarios. Use of a small-group teaching method to develop, implement, and critique clinical simulation scenarios facilitated critical thinking and clinical judgment of nursing students.

  7. Load and weather profile, and time simulation impacts for the PEPITE PV/H{sub 2} project

    Energy Technology Data Exchange (ETDEWEB)

    Darras, C.; Thibault, C.; Muselli, M.; Poggi, P. [University of Corsica, UMR CNRS SPE 6134, Route des Sanguinaires, F-20000 Ajaccio (France); Melscoet, S.; Hoguet, J.C. [HELION Hydrogen Power, Domaine du Petit Arbois - Batiment Jules Verne, BP 71, 13545 Aix en Provence (France); Pinton, E. [Commissariat a l' Energie Atomique (CEA/LITEN), 17 rue des Martyrs, 38 054 Grenoble Cedex 9 (France); Gailly, F.; Turpin, C. [Universite de Toulouse, INP, UPS, LAPLACE (Laboratoire Plasma et Conversion d' Energie), ENSEEIHT, 2 rue Charles Camichel, BP 7122, F-31071 Toulouse cedex 7 (France)


    This paper concerns the impacts of the meteorological data, the choice of the load profile, and the time simulation (1-11 years) on the energy flows and on the H{sub 2}/O{sub 2}/H{sub 2}O storage sizing in a photovoltaic/fuel cell/electrolyzer hybrid system (PEPITE project). The simulations were computed with the ORIENTE software. 4 load profiles have been investigated (3 diurnal and one nocturnal) with an identical daily consumption (26 kWh). According to load profiles, the gap observed between the most favorable and the most disadvantageous years induces H{sub 2} storage variations rates between 45.5% and 55.3%. Furthermore, if we compare the most penalizing meteorological year with the sizing when we simulate several successive years, we also obtain variation rates (ration between the standard deviation and the corresponding averaged value) ranges from 24.4 to 37.9% for the 3 diurnal profiles. The nocturnal profile presents specific results because it is unsustainable. The main conclusion of this work is the great importance to consider several consecutive years of tilted irradiation data, 7 in our case, to size the H{sub 2}/O{sub 2}/H{sub 2}O storages. (author)

  8. Neurite, a finite difference large scale parallel program for the simulation of electrical signal propagation in neurites under mechanical loading.

    Directory of Open Access Journals (Sweden)

    Julián A García-Grajales

    Full Text Available With the growing body of research on traumatic brain injury and spinal cord injury, computational neuroscience has recently focused its modeling efforts on neuronal functional deficits following mechanical loading. However, in most of these efforts, cell damage is generally only characterized by purely mechanistic criteria, functions of quantities such as stress, strain or their corresponding rates. The modeling of functional deficits in neurites as a consequence of macroscopic mechanical insults has been rarely explored. In particular, a quantitative mechanically based model of electrophysiological impairment in neuronal cells, Neurite, has only very recently been proposed. In this paper, we present the implementation details of this model: a finite difference parallel program for simulating electrical signal propagation along neurites under mechanical loading. Following the application of a macroscopic strain at a given strain rate produced by a mechanical insult, Neurite is able to simulate the resulting neuronal electrical signal propagation, and thus the corresponding functional deficits. The simulation of the coupled mechanical and electrophysiological behaviors requires computational expensive calculations that increase in complexity as the network of the simulated cells grows. The solvers implemented in Neurite--explicit and implicit--were therefore parallelized using graphics processing units in order to reduce the burden of the simulation costs of large scale scenarios. Cable Theory and Hodgkin-Huxley models were implemented to account for the electrophysiological passive and active regions of a neurite, respectively, whereas a coupled mechanical model accounting for the neurite mechanical behavior within its surrounding medium was adopted as a link between electrophysiology and mechanics. This paper provides the details of the parallel implementation of Neurite, along with three different application examples: a long myelinated axon

  9. Billion-atom synchronous parallel kinetic Monte Carlo simulations of critical 3D Ising systems (United States)

    Martínez, E.; Monasterio, P. R.; Marian, J.


    An extension of the synchronous parallel kinetic Monte Carlo (spkMC) algorithm developed by Martinez et al. [J. Comp. Phys. 227 (2008) 3804] to discrete lattices is presented. The method solves the master equation synchronously by recourse to null events that keep all processors' time clocks current in a global sense. Boundary conflicts are resolved by adopting a chessboard decomposition into non-interacting sublattices. We find that the bias introduced by the spatial correlations attendant to the sublattice decomposition is within the standard deviation of serial calculations, which confirms the statistical validity of our algorithm. We have analyzed the parallel efficiency of spkMC and find that it scales consistently with problem size and sublattice partition. We apply the method to the calculation of scale-dependent critical exponents in billion-atom 3D Ising systems, with very good agreement with state-of-the-art multispin simulations.

  10. Scenario-based Simulation of Criticality Concerning the Transportation of Dangerous Goods

    Directory of Open Access Journals (Sweden)

    Badea Dorel


    Full Text Available The critical infrastructure protection domain, through its social implications, is a relatively new research topic, and a science in this regard is not setup yet. Its complexity, through the operational subsumed areas, through the interdependencies and cascading possible effects, through the many facets for investigation, is a special one which imposes specific approaches. This paper intends to continue the investigations in this field, which are conducted in an individual manner or by research teams, by authors with concerns in this regard who agreed to allocate to the topical subject a special attention based on its importance, beyond an exclusive approach – as a special topic. This time, there are brought into attention the issues related to chemical industry sector correlated with actual associated implications of necessary transportation activities in this field. Simulation-based scenario is the main technique employed as a research methodology by using dedicated software.

  11. The influences of load mass changing on inverted pendulum stability based on simulation study (United States)

    Pangaribuan, Timbang; Nasruddin, M. N.; Marlianto, Eddy; Sigiro, Mula


    An inverted pendulum has nonlinear dynamic, so it is not easy to do in analysis to see its behavior. From many observations which have been made, there are two things that need to be added on the perfection of inverted pendulum. Firstly, when the pendulum has a large mass, and the second when the pendulum is given a load mass much larger than mass of the inverted pendulum. There are some question, first, how big the load mass can be given so that the movement of the inverted pendulum stay stable is. Second, how weight the changes and moves of load mass which can be given. For all the changes, it hopes the inverted pendulum is stay stable. Finally, the final result is still expected to be as stable, it must need conclude what kind of controller is capable of carrying such a mass burden, and how large the mass load limit can be given.

  12. Effect of an Outer Sleeve on an Inflatable Balloon Tamp in Terms of Height Restoration Under Simulated Physiological Load. (United States)

    Peppelman, Walter C; Beutler, William; Gordon, Michael; Chintakunta, Suresh R; O'Halloran, Damien; Bucklen, Brandon


    An in vitro biomechanical study. The aim of this study was to determine the effect of an optional sleeve on height restoration and compare it with the fracture reduction achieved by a commercially available inflatable bone tamp under simulated physiological load (110 N). Loss of reduction after bone tamp deflation before cement injection still remains a concern. The optional sleeve surrounds the bone tamp to help maintain height during the kyphoplasty procedure while filling the created cavity with bone cement on the contralateral side. Eighteen osteoporotic vertebral bodies (VBs) (T11-L4) were alternately assigned to 1 of the 2 treatment groups: group A: KYPHON (Kyphon Inc.) and group B: AFFIRM with sleeve (Globus Medical Inc.). The VBs were compressed axially at a rate of 5 mm/min until compressed to 40% of the initial anterior height. The fractured VBs then underwent kyphoplasty with cement augmentation while still maintaining load (110 N). The augmented VBs were then recompressed and anterior VB height (mm) and wedge angle (degrees) were measured initially after mechanically creating an anterior wedge fracture, and after repairing the compression fracture. The effect of kyphoplasty on vertebral height, kyphotic angle, cement volumes, and inflation pressures were compared between the treatment groups. Failure load (N) data were compared between intact and repaired VBs. Average percentage of lost VB height restored in group A was 30%, compared with 56% for group B. The mean changes in wedge angle were similar to those of vertebral height measurements. No significant difference in mean inflation pressures (group A: 175±37 psi; group B: 160±36 psi) were found between the 2 groups. Average percentage increase in failure load was 241% and 212% in groups A and B, respectively. Some height restoration was observed using the commercially available bone tamp in fractured VBs under simulated physiological load. The use of an outer sleeve significantly enhanced height

  13. Numerical Simulation of Output Response of PVDF Sensor Attached on a Cantilever Beam Subjected to Impact Loading. (United States)

    Dung, Cao Vu; Sasaki, Eiichi


    Polyvinylidene Flouride (PVDF) is a film-type polymer that has been used as sensors and actuators in various applications due to its mechanical toughness, flexibility, and low density. A PVDF sensor typically covers an area of the host structure over which mechanical stress/strain is averaged and converted to electrical energy. This study investigates the fundamental "stress-averaging" mechanism for dynamic strain sensing in the in-plane mode. A numerical simulation was conducted to simulate the "stress-averaging" mechanism of a PVDF sensor attached on a cantilever beam subjected to an impact loading, taking into account the contribution of piezoelectricity, the cantilever beam's modal properties, and electronic signal conditioning. Impact tests and FEM analysis were also carried out to verify the numerical simulation results. The results of impact tests indicate the excellent capability of the attached PVDF sensor in capturing the fundamental natural frequencies of the cantilever beam. There is a good agreement between the PVDF sensor's output voltage predicted by the numerical simulation and that obtained in the impact tests. Parametric studies were conducted to investigate the effects of sensor size and sensor position and it is shown that a larger sensor tends to generate higher output voltage than a smaller one at the same location. However, the effect of sensor location seems to be more significant for larger sensors due to the cancelling problem. Overall, PVDF sensors exhibit excellent sensing capability for in-plane dynamic strain induced by impact loading.

  14. Tetramethylpyrazine-Loaded Hydrogels: Preparation, Penetration Through a Subcutaneous-Mucous-Membrane Model, and a Molecular Dynamics Simulation. (United States)

    Xia, Hongmei; Xu, Yinxiang; Cheng, Zhiqing; Cheng, Yongfeng


    Tetramethylpyrazine (TMP) was extracted from Ligusticum chuanxiong hort. The compound is known to have a variety of medicinal functions; in particular, it is used for the treatment of cerebral ischemic diseases. TMP-loaded hydrogels offer an excellent preparation with the capacity to bypass the blood-brain barrier, allowing treatment of the brain through intranasal administration. We prepared TMP-loaded hydrogels using carbomer 940 and evaluated the release of TMP from the hydrogel. We determined the release rate using Franz-type diffusion cell experiments with a subcutaneous-mucous-membrane model and also by a molecular dynamics (MD) simulation. In general, the former method was more complicated than the latter was. The dynamic behavior of TMP release from the hydrogel was revealed by analysis of the mean square displacement of the trajectory in the MD simulation. The coefficient of TMP diffusion from the hydrogel was calculated at different temperatures (277, 298, and 310 K) by using MD software. The results showed that the coefficient of diffusion increased with an increase in temperature. This trend was observed both experimentally and in the MD simulation. Therefore, the MD simulation was a complementary method to verify the experimental data.

  15. Simulations of potential future conditions in the cache critical groundwater area, Arkansas (United States)

    Rashid, Haveen M.; Clark, Brian R.; Mahdi, Hanan H.; Rifai, Hanadi S.; Al-Shukri, Haydar J.


    A three-dimensional finite-difference model for part of the Mississippi River Valley alluvial aquifer in the Cache Critical Groundwater Area of eastern Arkansas was constructed to simulate potential future conditions of groundwater flow. The objectives of this study were to test different pilot point distributions to find reasonable estimates of aquifer properties for the alluvial aquifer, to simulate flux from rivers, and to demonstrate how changes in pumping rates for different scenarios affect areas of long-term water-level declines over time. The model was calibrated using the parameter estimation code. Additional calibration was achieved using pilot points with regularization and singular value decomposition. Pilot point parameter values were estimated at a number of discrete locations in the study area to obtain reasonable estimates of aquifer properties. Nine pumping scenarios for the years 2011 to 2020 were tested and compared to the simulated water-level heads from 2010. Hydraulic conductivity values from pilot point calibration ranged between 42 and 173 m/d. Specific yield values ranged between 0.19 and 0.337. Recharge rates ranged between 0.00009 and 0.0006 m/d. The model was calibrated using 2,322 hydraulic head measurements for the years 2000 to 2010 from 150 observation wells located in the study area. For all scenarios, the volume of water depleted ranged between 5.7 and 23.3 percent, except in Scenario 2 (minimum pumping rates), in which the volume increased by 2.5 percent.

  16. Loads in the design of flight vehicles




    The calculation of flight loads is a critical part of air vehicle design. On the other hand, the prediction of accurate loads is a sophisticated and complex process that requires skilled and experienced engineers. They must integrate results from wind tunnel tests, computer simulations, historical data and empirical formulations into a number of loads cases that provide a realistic assessment of the flight vehicle’s environment. Under these conditions, the vehicle must satisfy requirements im...

  17. Advanced simulation for analysis of critical infrastructure : abstract cascades, the electric power grid, and Fedwire.

    Energy Technology Data Exchange (ETDEWEB)

    Glass, Robert John, Jr.; Stamber, Kevin Louis; Beyeler, Walter Eugene


    Critical Infrastructures are formed by a large number of components that interact within complex networks. As a rule, infrastructures contain strong feedbacks either explicitly through the action of hardware/software control, or implicitly through the action/reaction of people. Individual infrastructures influence others and grow, adapt, and thus evolve in response to their multifaceted physical, economic, cultural, and political environments. Simply put, critical infrastructures are complex adaptive systems. In the Advanced Modeling and Techniques Investigations (AMTI) subgroup of the National Infrastructure Simulation and Analysis Center (NISAC), we are studying infrastructures as complex adaptive systems. In one of AMTI's efforts, we are focusing on cascading failure as can occur with devastating results within and between infrastructures. Over the past year we have synthesized and extended the large variety of abstract cascade models developed in the field of complexity science and have started to apply them to specific infrastructures that might experience cascading failure. In this report we introduce our comprehensive model, Polynet, which simulates cascading failure over a wide range of network topologies, interaction rules, and adaptive responses as well as multiple interacting and growing networks. We first demonstrate Polynet for the classical Bac, Tang, and Wiesenfeld or BTW sand-pile in several network topologies. We then apply Polynet to two very different critical infrastructures: the high voltage electric power transmission system which relays electricity from generators to groups of distribution-level consumers, and Fedwire which is a Federal Reserve service for sending large-value payments between banks and other large financial institutions. For these two applications, we tailor interaction rules to represent appropriate unit behavior and consider the influence of random transactions within two stylized networks: a regular homogeneous array

  18. Evaluation of atmospheric pollution in the soils in Madrid: the critical load concept; Evaluacion del impacto que la contaminacion atmosferica origina en los suelos de la comunidad de Madrid: El concepto de cargas criticas

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez Cabrero, B.; Jimenez Ballesta, R.; Gutierrez Marota, A. [Departamento de Quimica Agricola, Geologia y Geoquimica, Universidad Autonoma de Madrid (Spain)


    The increase of industrial activities in the origin of atmospheric emissions and damage in the earth. In order to calculate the effective control of SO{sub {sup .}} NO{sub x}, NH{sub 3} a new concept is proposed the critical loads. This concept was proposed by Nilsson and Grennfelt to calculate this acidification load in the ecosystem without damage ecological effects. This article presents the critical load in the soils of Madrid.

  19. Notes From the Field: Secondary Task Precision for Cognitive Load Estimation During Virtual Reality Surgical Simulation Training. (United States)

    Rasmussen, Sebastian R; Konge, Lars; Mikkelsen, Peter T; Sørensen, Mads S; Andersen, Steven A W


    Cognitive load (CL) theory suggests that working memory can be overloaded in complex learning tasks such as surgical technical skills training, which can impair learning. Valid and feasible methods for estimating the CL in specific learning contexts are necessary before the efficacy of CL-lowering instructional interventions can be established. This study aims to explore secondary task precision for the estimation of CL in virtual reality (VR) surgical simulation and also investigate the effects of CL-modifying factors such as simulator-integrated tutoring and repeated practice. Twenty-four participants were randomized for visual assistance by a simulator-integrated tutor function during the first 5 of 12 repeated mastoidectomy procedures on a VR temporal bone simulator. Secondary task precision was found to be significantly lower during simulation compared with nonsimulation baseline, p < .001. Contrary to expectations, simulator-integrated tutoring and repeated practice did not have an impact on secondary task precision. This finding suggests that even though considerable changes in CL are reflected in secondary task precision, it lacks sensitivity. In contrast, secondary task reaction time could be more sensitive, but requires substantial postprocessing of data. Therefore, future studies on the effect of CL modifying interventions should weigh the pros and cons of the various secondary task measurements. © The Author(s) 2015.

  20. Cirrus Parcel Model Comparison Project. Phase 1; The Critical Components to Simulate Cirrus Initiation Explicitly (United States)

    Lin, Ruei-Fong; Starr, David OC; DeMott, Paul J.; Cotton, Richard; Sassen, Kenneth; Jensen, Eric; Einaudi, Franco (Technical Monitor)


    The Cirrus Parcel Model Comparison Project, a project of the GCSS (GEWEX Cloud System Studies) Working Group on Cirrus Cloud Systems, involves the systematic comparison of current models of ice crystal nucleation and growth for specified, typical, cirrus cloud environments. In Phase I of the project reported here, simulated cirrus cloud microphysical properties are compared for situations of "warm" (40 C) and "cold" (-60 C) cirrus, both subject to updrafts of 4, 20 and 100 centimeters per second. Five models participated. The various models employ explicit microphysical schemes wherein the size distribution of each class of particles (aerosols and ice crystals) is resolved into bins or treated separately. Simulations are made including both the homogeneous and heterogeneous ice nucleation mechanisms. A single initial aerosol population of sulfuric acid particles is prescribed for all simulations. To isolate the treatment of the homogeneous freezing (of haze droplets) nucleation process, the heterogeneous nucleation mechanism is disabled for a second parallel set of simulations. Qualitative agreement is found for the homogeneous-nucleation- only simulations, e.g., the number density of nucleated ice crystals increases with the strength of the prescribed updraft. However, significant quantitative differences are found. Detailed analysis reveals that the homogeneous nucleation rate, haze particle solution concentration, and water vapor uptake rate by ice crystal growth (particularly as controlled by the deposition coefficient) are critical components that lead to differences in predicted microphysics. Systematic bias exists between results based on a modified classical theory approach and models using an effective freezing temperature approach to the treatment of nucleation. Each approach is constrained by critical freezing data from laboratory studies, but each includes assumptions that can only be justified by further laboratory research. Consequently, it is not yet

  1. Effect of working memory load on electrophysiological markers of visuospatial orienting in a spatial cueing task simulating a traffic situation. (United States)

    Vossen, Alexandra Y; Ross, Veerle; Jongen, Ellen M M; Ruiter, Robert A C; Smulders, Fren T Y


    Visuospatial attentional orienting has typically been studied in abstract tasks with low ecological validity. However, real-life tasks such as driving require allocation of working memory (WM) resources to several subtasks over and above orienting in a complex sensory environment. The aims of this study were twofold: firstly, to establish whether electrophysiological signatures of attentional orienting commonly observed under simplified task conditions generalize to a more naturalistic task situation with realistic-looking stimuli, and, secondly, to assess how these signatures are affected by increased WM load under such conditions. Sixteen healthy participants performed a dual task consisting of a spatial cueing paradigm and a concurrent verbal memory task that simulated aspects of an actual traffic situation. Behaviorally, we observed a load-induced detriment of sensitivity to targets. In the EEG, we replicated orienting-related alpha lateralization, the lateralized ERPs ADAN, EDAN, and LDAP, and the P1-N1 attention effect. When WM load was high (i.e., WM resources were reduced), lateralization of oscillatory activity in the lower alpha band was delayed. In the ERPs, we found that ADAN was also delayed, while EDAN was absent. Later ERP correlates were unaffected by load. Our results show that the findings in highly controlled artificial tasks can be generalized to spatial orienting in ecologically more valid tasks, and further suggest that the initiation of spatial orienting is delayed when WM demands of an unrelated secondary task are high. © 2015 Society for Psychophysiological Research.

  2. Application of powerful quasi-steady-state plasma accelerators for simulation of ITER transient heat loads on divertor surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Tereshin, V I [Institute of Plasma Physics of the NSC KIPT, Kharkov 61108 (Ukraine); Bandura, A N [Institute of Plasma Physics of the NSC KIPT, Kharkov 61108 (Ukraine); Byrka, O V [Institute of Plasma Physics of the NSC KIPT, Kharkov 61108 (Ukraine); Chebotarev, V V [Institute of Plasma Physics of the NSC KIPT, Kharkov 61108 (Ukraine); Garkusha, I E [Institute of Plasma Physics of the NSC KIPT, Kharkov 61108 (Ukraine); Landman, I [Forschungszentrum Karlsruhe, IHM, Karlsruhe 76021 (Germany); Makhlaj, V A [Institute of Plasma Physics of the NSC KIPT, Kharkov 61108 (Ukraine); Neklyudov, I M [Institute of Plasma Physics of the NSC KIPT, Kharkov 61108 (Ukraine); Solyakov, D G [Institute of Plasma Physics of the NSC KIPT, Kharkov 61108 (Ukraine); Tsarenko, A V [Institute of Plasma Physics of the NSC KIPT, Kharkov 61108 (Ukraine)


    The paper presents the investigations of high power plasma interaction with material surfaces under conditions simulating the ITER disruptions and type I ELMs. Different materials were exposed to plasma with repetitive pulses of 250 {mu}s duration, the ion energy of up to 0.6 keV, and the heat loads varying in the 0.5-25 MJ m{sup -2} range. The plasma energy transfer to the material surface versus impact load has been analysed. The fraction of plasma energy that is absorbed by the target surface is rapidly decreased with the achievement of the evaporation onset for exposed targets. The distributions of evaporated material in front of the target surface and the thickness of the shielding layer are found to be strongly dependent on the target atomic mass. The surface analysis of tungsten targets exposed to quasi-steady-state plasma accelerators plasma streams is presented together with measurements of the melting onset load and evaporation threshold, and also of erosion patterns with increasing heat load and the number of plasma pulses.

  3. Application of powerful quasi-steady-state plasma accelerators for simulation of ITER transient heat loads on divertor surfaces (United States)

    Tereshin, V. I.; Bandura, A. N.; Byrka, O. V.; Chebotarev, V. V.; Garkusha, I. E.; Landman, I.; Makhlaj, V. A.; Neklyudov, I. M.; Solyakov, D. G.; Tsarenko, A. V.


    The paper presents the investigations of high power plasma interaction with material surfaces under conditions simulating the ITER disruptions and type I ELMs. Different materials were exposed to plasma with repetitive pulses of 250 µs duration, the ion energy of up to 0.6 keV, and the heat loads varying in the 0.5-25 MJ m-2 range. The plasma energy transfer to the material surface versus impact load has been analysed. The fraction of plasma energy that is absorbed by the target surface is rapidly decreased with the achievement of the evaporation onset for exposed targets. The distributions of evaporated material in front of the target surface and the thickness of the shielding layer are found to be strongly dependent on the target atomic mass. The surface analysis of tungsten targets exposed to quasi-steady-state plasma accelerators plasma streams is presented together with measurements of the melting onset load and evaporation threshold, and also of erosion patterns with increasing heat load and the number of plasma pulses.

  4. Repetitive Plasma Loads Typical for ITER Type-I ELMS: Simulation in QSPA Kh-50 (United States)

    Tereshin, V. I.; Bandura, A. N.; Byrka, O. V.; Chebotarev, V. V.; Garkusha, I. E.; Landman, I.; Makhlaj, V. A.; Solyakov, D. G.; Tsarenko, A. V.


    The paper presents energy characteristics of the plasma streams generated with quasi-steady-state plasma accelerator QSPA Kh-50 and the main features of plasma interaction with tungsten surfaces in dependence on plasma heat loads. The samples of pure sintered tungsten of EU trademark have been exposed to hydrogen plasma streams. The experiments were performed with up to 450 pulses (pulse duration of 0.25 ms) and the surface heat loads in the range of (0.45 - 1.2) MJ/m2. A threshold character of morphological changes on the melt tungsten surface with the pulses number is demonstrated. The number of initial exposures without formation of corrugations and pits is about 200, which does not depend on the target heat load magnitude. Further increase of the exposures results in the corrugation structures becoming dominant. The melt layer disintegrates into a set of droplets remaining at the surface. Such evolution seems to be driven by the surface tension forces within the fine cells of crack network. Finally a stabilization of the surface pattern occurs. The onset of intensive evaporation at molten tungsten surface under the repetitive heat loads has also been studied. The evaporation can result in enhanced mass losses: increase of the heat load from 0.75 to 1.1 MJ/m2 rises mass losses for one order of magnitude and causes bubble structures at the surface. Due to evaporation, the erosion crater grows with the rate of 0.04 μm/pulse. It was obtained, that for ELM-like repetitive loads the melt motion driven by plasma pressure gradient did not contribute significantly to the erosion profile.

  5. Modelling and mapping critical loads and exceedances for the Georgia Basin, British Columbia, using a zero base-cation depletion criterion

    Directory of Open Access Journals (Sweden)

    Beverley A. RAYMOND†


    Full Text Available Critical load (CL and exceedance maps of sulphur (S and nitrogen (N for upland soils were generated for the Georgia Basin, British Columbia, Canada, by synthesizing available data layers for atmospheric deposition, climate (precipitation, temperature, soil, site classification and elevation. Critical loads were determined using the steady-state mass-balance model and a criterion based on zero-tolerance for further base-cation depletion. The resulting CL values were generally lowest on ridge tops and increased towards valleys. Critical load exceedance ranged from 13% of the Georgia Basin under wet deposition to 32% under modelled total (wet and dry deposition. Moreover, exceedance increased by an additional 10% when considering upland areas only for the Georgia Basin. Significant portions of the Georgia Basin are predicted to experience exceedance-enhanced base-cation depletion rates above 200 eq ha–1 y–1 and turn-over times to a final new base saturation state within 200 years under continued atmospheric S and N deposition.

  6. The effect of implementing cognitive load theory-based design principles in virtual reality simulation training of surgical skills: a randomized controlled trial

    DEFF Research Database (Denmark)

    Andersen, Steven Arild Wuyts; Mikkelsen, Peter Trier; Konge, Lars


    . Increased cognitive load when part tasks needed to be integrated in the post-training procedures could be a possible explanation for this. Other instructional designs and methods are needed to lower the cognitive load and improve the performance in virtual reality surgical simulation training of novices.......Background Cognitive overload can inhibit learning, and cognitive load theory-based instructional design principles can be used to optimize learning situations. This study aims to investigate the effect of implementing cognitive load theory-based design principles in virtual reality simulation...... training of mastoidectomy. Methods Eighteen novice medical students received 1 h of self-directed virtual reality simulation training of the mastoidectomy procedure randomized for standard instructions (control) or cognitive load theory-based instructions with a worked example followed by a problem...

  7. Investigation of the dependency of wind turbine loads on the simulation time


    Tibaldi, Carlo; Henriksen, Lars Christian; Bak, Christian


    In this work the dependency of several wind turbine parameters with respect to the length of simulations used for their evaluation is investigated. The analysis is performed by computing the parameters with a different number of turbulent wind simulations, therefore simulation time, and repeating the computation with different turbulence realizations. The repetition of the computation is performed to identify the scatter of the parameters for a given number of turbulent seeds due to the diffe...

  8. A Load Balancing Scheme Using Federate Migration Based on Virtual Machines for Cloud Simulations

    Directory of Open Access Journals (Sweden)

    Xiao Song


    Full Text Available A maturing and promising technology, Cloud computing can benefit large-scale simulations by providing on-demand, anywhere simulation services to users. In order to enable multitask and multiuser simulation systems with Cloud computing, Cloud simulation platform (CSP was proposed and developed. To use key techniques of Cloud computing such as virtualization to promote the running efficiency of large-scale military HLA systems, this paper proposes a new type of federate container, virtual machine (VM, and its dynamic migration algorithm considering both computation and communication cost. Experiments show that the migration scheme effectively improves the running efficiency of HLA system when the distributed system is not saturated.

  9. Treatment of compounds and alloys in radiation hydrodynamics simulations of ablative laser loading. (United States)

    Swift, Damian C; Gammel, J Tinka; Clegg, Samuel M


    Different methods were compared for constructing models of the behavior of a prototype intermetallic compound, nickel aluminide, for use in radiation hydrodynamics simulations of shock wave generation by ablation induced by laser energy. The models included the equation of state, ionization, and radiation opacity. The methods of construction were evaluated by comparing the results of simulations of an ablatively generated shock wave in a sample of the alloy. The most accurate simulations were obtained using the "constant number density" mixture model to calculate the equation of state and opacity, and Thomas-Fermi ionization. This model is consistent with that found to be most accurate for simulations of ablatively shocked elements.

  10. Simulation on breakage of heterogeneous materials caused by detonative loading; Bakugo shogeki ni yoru fukinshitsu zairyo no hakai gensho no simulation

    Energy Technology Data Exchange (ETDEWEB)

    Sassa, K.; Watanabe, T.; Ashida, Y. [Kyoto University, Kyoto (Japan). Faculty of Engineering


    Investigations were conducted by simulation of breakage of inhomogeneous materials (rock) attributable to detonative loading, which simulation used the Days-2 Code. During the simulation, one-free-face blastings were used for testing a homogeneous structure, horizontal 2-layer structure, and horizontal 3-layer structure. Property values were assigned to the rocks on the assumption that they were sedimentary rocks such as sandstone or mudstone or hard rocks such as granite. As the result, it was found that a detonative loading resulted in shear failure in a sphere near the focus that was followed by radially developed cracks due to tension breakage, that more area is damaged in a soft rock than in a hard rock, that cracks due to breakage are produced by the overlapping of waves directly from the focus and those reflected from the free face in case of one-free-face blastings, that such cracks propagated along the soft rock layer in case there is a soft rock layer in a hard rock, but that breakage does not extend beyond the soft rock layer. 6 refs., 6 figs., 1 tab.

  11. Suppression of the initial transient in Monte Carlo criticality simulations; Suppression du regime transitoire initial des simulations Monte-Carlo de criticite

    Energy Technology Data Exchange (ETDEWEB)

    Richet, Y


    Criticality Monte Carlo calculations aim at estimating the effective multiplication factor (k-effective) for a fissile system through iterations simulating neutrons propagation (making a Markov chain). Arbitrary initialization of the neutron population can deeply bias the k-effective estimation, defined as the mean of the k-effective computed at each iteration. A simplified model of this cycle k-effective sequence is built, based on characteristics of industrial criticality Monte Carlo calculations. Statistical tests, inspired by Brownian bridge properties, are designed to discriminate stationarity of the cycle k-effective sequence. The initial detected transient is, then, suppressed in order to improve the estimation of the system k-effective. The different versions of this methodology are detailed and compared, firstly on a plan of numerical tests fitted on criticality Monte Carlo calculations, and, secondly on real criticality calculations. Eventually, the best methodologies observed in these tests are selected and allow to improve industrial Monte Carlo criticality calculations. (author)

  12. Fusing Simulation Results From Multifidelity Aero-servo-elastic Simulators - Application To Extreme Loads On Wind Turbine

    DEFF Research Database (Denmark)

    Abdallah, Imad; Sudret, Bruno; Lataniotis, Christos


    Fusing predictions from multiple simulators in the early stages of the conceptual design of a wind turbine results in reduction in model uncertainty and risk mitigation. Aero-servo-elastic is a term that refers to the coupling of wind inflow, aerodynamics, structural dynamics and controls. Fusing...

  13. Finite element simulation of structural performance on flexible pavements with stabilized base/treated subbase materials under accelerated loading : tech summary. (United States)


    Accelerated pavement testing (APT) has been increasingly used by state highway agencies in recent years for evaluating pavement : design and performance through applying a simulative heavy vehicular load to the pavement section under controlled fi el...

  14. Development of total maximum daily loads for bacteria impaired watershed using the comprehensive hydrology and water quality simulation model. (United States)

    Kim, Sang M; Brannan, Kevin M; Zeckoski, Rebecca W; Benham, Brian L


    The objective of this study was to develop bacteria total maximum daily loads (TMDLs) for the Hardware River watershed in the Commonwealth of Virginia, USA. The TMDL program is an integrated watershed management approach required by the Clean Water Act. The TMDLs were developed to meet Virginia's water quality standard for bacteria at the time, which stated that the calendar-month geometric mean concentration of Escherichia coli should not exceed 126 cfu/100 mL, and that no single sample should exceed a concentration of 235 cfu/100 mL. The bacteria impairment TMDLs were developed using the Hydrological Simulation Program-FORTRAN (HSPF). The hydrology and water quality components of HSPF were calibrated and validated using data from the Hardware River watershed to ensure that the model adequately simulated runoff and bacteria concentrations. The calibrated and validated HSPF model was used to estimate the contributions from the various bacteria sources in the Hardware River watershed to the in-stream concentration. Bacteria loads were estimated through an extensive source characterization process. Simulation results for existing conditions indicated that the majority of the bacteria came from livestock and wildlife direct deposits and pervious lands. Different source reduction scenarios were evaluated to identify scenarios that meet both the geometric mean and single sample maximum E. coli criteria with zero violations. The resulting scenarios required extreme and impractical reductions from livestock and wildlife sources. Results from studies similar to this across Virginia partially contributed to a reconsideration of the standard's applicability to TMDL development.


    Directory of Open Access Journals (Sweden)

    Doroshenko Sergey Aleksandrovich


    Full Text Available The authors discuss wind loads applied to a set of two buildings. The wind load is simulated with the help of the wind tunnel. In the Russian Federation, special attention is driven to the aerodynamics of high-rise buildings and structures. According to the Russian norms, identification of aerodynamic coefficients for high-rise buildings, as well as the influence of adjacent buildings and structures, is performed on the basis of models of structures exposed to wind impacts simulated in the wind tunnel. This article deals with the results of the wind tunnel test of buildings. The simulation was carried out with the involvement of a model of two twenty-three storied buildings. The experiment was held in a wind tunnel of the closed type at in the Institute of Mechanics of Moscow State University. Data were compared at the zero speed before and after the experiment. LabView software was used to process the output data. Graphs and tables were developed in the Microsoft Excel package. GoogleSketchUp software was used as a visualization tool. The three-dimensional flow formed in the wind tunnel can't be adequately described by solving the two-dimensional problem. The aerodynamic experiment technique is used to analyze the results for eighteen angles of the wind attack.

  16. Simulating sediment loading into the major reservoirs in Trinity River Basin (United States)

    The Upper Trinity Basin supplies water to about one-fourth of Texas' population. The anticipated rapid growth of North Central Texas will certainly increase regional demands for high quality drinking water. This has increased concerns that sediment and nutrient loads received by drinking water reser...

  17. Simulation of disaggregated load profiles and development of a proxy microgrid for modelling purposes

    NARCIS (Netherlands)

    Zeyringer, Marianne; Andrews, David; Schmid, Erwin; Schmidt, Johannes; Worrell, Ernst


    The deployment of small-scale renewable energy technologies affects the electricity grid depending on the local resource potential as well as on the regional composition of consumers. Spatially explicit renewable energy supply data and spatially disaggregated load profiles of consumers are usually

  18. Effect of unloading and loading on power in simulated countermovement and squat jumps

    NARCIS (Netherlands)

    Bobbert, M.F.


    PURPOSE: In the literature, substantial decreases in power output in jumping have been described for both unloading and loading, and these have been attributed to the intrinsic force-velocity-power relationship of muscle. The purpose of this study was to gain a solid understanding of how and why

  19. The effect of implementing cognitive load theory-based design principles in virtual reality simulation training of surgical skills: a randomized controlled trial

    DEFF Research Database (Denmark)

    Andersen, Steven Arild Wuyts; Mikkelsen, Peter Trier; Konge, Lars


    Cognitive overload can inhibit learning, and cognitive load theory-based instructional design principles can be used to optimize learning situations. This study aims to investigate the effect of implementing cognitive load theory-based design principles in virtual reality simulation training...

  20. Numerical simulations for classification of blast loaded laminated glass: Possibilities, limitations and recommendations

    NARCIS (Netherlands)

    Stolz, A.; C, K.; Doormaal, J.C.A.M. van; Haberacker, C.; Hüsken, G.; Larcher, M.; Saarenheimo, A.; Solomos, G.; Stolz, A.; Thamie, L.; Bedon, C.


    It is important to protect critical buildings (shopping centres, government buildings and embassies), infrastructure and utilities, train and underground stations against being damaged, destroyed or disrupted by deliberate acts of terrorism, criminal activity and malicious behaviour. Normal

  1. Mechanical Characterization and Finite Element Implementation of the SoftMaterials used in a Novel Anthropometric Test Device for SimulatingUnderbody Blast Loading (United States)


    Materials used in a Novel Anthropometric Test Device for Simulating Underbody Blast Loading by Wade A Baker, Costin D Untaroiu, Dawn M Crawford, and...used in a Novel Anthropometric Test Device for Simulating Underbody Blast Loading by Wade A Baker and Costin D Untaroiu Virginia Tech, Department...SUBTITLE Mechanical Characterization and Finite Element Implementation of the Soft Materials used in a Novel Anthropometric Test Device for

  2. Finite element simulation on posterior tibial tendinopathy: Load transfer alteration and implications to the onset of pes planus. (United States)

    Wong, Duo Wai-Chi; Wang, Yan; Leung, Aaron Kam-Lun; Yang, Ming; Zhang, Ming


    Posterior tibial tendinopathy is a challenging foot condition resulting in pes planus, which is difficult to diagnose in the early stage. Prior to the deformity, abnormal internal load transfer and soft tissue attenuation are anticipated. The objective of this study was to investigate the internal load transfer and strain of the ligaments with posterior tibial tendinopathy, and the implications to pes planus and other deformities. A three-dimensional finite element model of the foot and ankle was reconstructed from magnetic resonance images of a 28-year-old normal female. Thirty bones, plantar fascia, ligaments and tendons were reconstructed. With the gait analysis data of the model subject, walking stance was simulated. The onset of posterior tibial tendinopathy was resembled by unloading the tibialis posterior and compared to the normal condition. The load transfer of the joints at the proximal medial column was weaken by posterior tibial tendinopathy, which was compromised by the increase along the lateral column and the intercuneiforms during late stance. Besides, the plantar tarsometatarsal and cuboideonavicular ligaments were consistently over-stretched during stance. Particularly, the maximum tensile strain of the plantar tarsometatarsal ligament was about 3-fold higher than normal at initial push-off. Posterior tibial tendinopathy altered load transfer of the medial column and unbalanced the load between the proximal and distal side of the medial longitudinal arch. Posterior tibial tendinopathy also stretched the midfoot plantar ligaments that jeopardized midfoot stability, and attenuated the transverse arch. All these factors potentially contributed to the progress of pes planus and other foot deformities. Copyright © 2017. Published by Elsevier Ltd.

  3. ArcNLET: A GIS-based software to simulate groundwater nitrate load from septic systems to surface water bodies (United States)

    Rios, J. Fernando; Ye, Ming; Wang, Liying; Lee, Paul Z.; Davis, Hal; Hicks, Rick


    Onsite wastewater treatment systems (OWTS), or septic systems, can be a significant source of nitrates in groundwater and surface water. The adverse effects that nitrates have on human and environmental health have given rise to the need to estimate the actual or potential level of nitrate contamination. With the goal of reducing data collection and preparation costs, and decreasing the time required to produce an estimate compared to complex nitrate modeling tools, we developed the ArcGIS-based Nitrate Load Estimation Toolkit (ArcNLET) software. Leveraging the power of geographic information systems (GIS), ArcNLET is an easy-to-use software capable of simulating nitrate transport in groundwater and estimating long-term nitrate loads from groundwater to surface water bodies. Data requirements are reduced by using simplified models of groundwater flow and nitrate transport which consider nitrate attenuation mechanisms (subsurface dispersion and denitrification) as well as spatial variability in the hydraulic parameters and septic tank distribution. ArcNLET provides a spatial distribution of nitrate plumes from multiple septic systems and a load estimate to water bodies. ArcNLET's conceptual model is divided into three sub-models: a groundwater flow model, a nitrate transport and fate model, and a load estimation model which are implemented as an extension to ArcGIS. The groundwater flow model uses a map of topography in order to generate a steady-state approximation of the water table. In a validation study, this approximation was found to correlate well with a water table produced by a calibrated numerical model although it was found that the degree to which the water table resembles the topography can vary greatly across the modeling domain. The transport model uses a semi-analytical solution to estimate the distribution of nitrate within groundwater, which is then used to estimate a nitrate load using a mass balance argument. The estimates given by ArcNLET are

  4. Modeling and simulation of stand-alone hybrid power system with fuzzy MPPT for remote load application

    Directory of Open Access Journals (Sweden)

    Bogaraj T.


    Full Text Available Many parts of remote locations in the world are not electrified even in this Advanced Technology Era. To provide electricity in such remote places renewable hybrid energy systems are very much suitable. In this paper PV/Wind/Battery Hybrid Power System (HPS is considered to provide an economical and sustainable power to a remote load. HPS can supply the maximum power to the load at a particular operating point which is generally called as Maximum Power Point (MPP. Fuzzy Logic based MPPT (FLMPPT control method has been implemented for both Solar and Wind Power Systems. FLMPPT control technique is implemented to generate the optimal reference voltage for the first stage of DC-DC Boost converter in both the PV and Wind energy system. The HPS is tested with variable solar irradiation, temperature, and wind speed. The FLMPPT method is compared with P&O MPPT method. The proposed method provides a good maximum power operation of the hybrid system at all operating conditions. In order to combine both sources, the DC bus voltage is made constant by employing PI Controllers for the second stage of DC-DC Buck-Boost converter in both Solar and Wind Power Systems. Battery Bank is used to store excess power from Renewable Energy Sources (RES and to provide continuous power to load when the RES power is less than load power. A SPWM inverter is designed to convert DC power into AC to supply three phase load. An LC filter is also used at the output of inverter to get sinusoidal current from the PWM inverter. The entire system was modeled and simulated in Matlab/Simulink Environment. The results presented show the validation of the HPS design.

  5. Probability based load criteria for the design of nuclear structures: a critical review of the state-of-the-art

    Energy Technology Data Exchange (ETDEWEB)

    Shinozuka, M.; Ellingwood, B.R.; Wang, P.C.; Meyer, C.; Wen, Y.K.; Kao, S.; Shooman, M.L.; Philippacopoulos, A.J.


    Structures for nuclear power plant facilities must be designed to withstand safely and effectively all kinds of loads and load combinations that may be expected to occur during their lifetime. The traditional methods of structural design attempt to account for the inevitable variability in the loads, material strengths, in-service environments, and fabrication process, etc., through the use of safety factor, allowable stresses or load and resistance factors. These approaches may result in an unknown and nonuniform reliability because of the subjective manner in which the safety factors have been determined. The stochastic nature loads and the uncertainties in material properties dictate a probabilistic approach for a rational assessment of structural safety and performance. This report presents: an in-depth review of the state-of-the-art pertaining to probability-based analysis and design of civil engineering structures; basis for extending existing probability-based methods to seismic category I nuclear structures; and the availability of the pertinent data required to perform probabilistic analysis for seismic category I nuclear structures.

  6. The determination of equivalent bearing loading for the BSMT that simulate SSME high pressure oxidizer turbopump conditions using the SHABERTH/SINDA computer programs (United States)

    Mcdonald, Gary H.


    The MSFC bearing seal material tester (BSMT) can be used to evaluate the SSME high pressure oxygen turbopump (HPOTP) bearing performance. The four HPOTP bearings have both an imposed radial and axial load. These radial and axial loads are caused by the HPOTP's shaft, main impeller, preburner impeller, turbine and by the LOX coolant flow through the bearings, respectively. These loads coupled with bearing geometry and operating speed can define bearing contact angle, contact Hertz stress, and heat generation rates. The BSMT has the capability of operating at HPOTP shaft speeds, provide proper coolant flowrates but can only apply an axial load. Due to the inability to operate the bearings in the BSMT with an applied radial load, it is important to develop an equivalency between the applied axial loads and the actual HPOTP loadings. A shaft-bearing-thermal computer code (SHABERTH/SINDA) is used to simulate the BSMT bearing-shaft geometry and thermal-fluid operating conditions.

  7. 3-D numerical simulation of Yb:YAG active slabs with longitudinal doping gradient for thermal load effects assessment. (United States)

    Ferrara, P; Ciofini, M; Esposito, L; Hostaša, J; Labate, L; Lapucci, A; Pirri, A; Toci, G; Vannini, M; Gizzi, L A


    We present a study of Yb:YAG active media slabs, based on a ceramic layered structure with different doping levels. We developed a procedure allowing 3D numerical analysis of the slab optical properties as a consequence of the thermal load induced by the pump process. The simulations are compared with a set of experimental results in order to validate the procedure. These structured ceramics appear promising in appropriate geometrical configurations, and thus are intended to be applied in the construction of High Energy Diode Pumped Solid State Laser (DPSSL) systems working in high repetition-rate pulsed regimes.

  8. Low velocity impact monitoring of composite wing structure under simulated wing loading condition using fiber Bragg grating sensors (United States)

    Shrestha, Pratik; Park, Yurim; Kwon, Hyunseok; Kim, Chun-Gon


    A low velocity impact onto a composite structure can result in the occurrence of barely visible impact damage (BVID), which is difficult to detect. Therefore, the low velocity impact monitoring of composite structures is highly desirable for impact detection and localization. In this paper, low velocity impacts on a composite wing under a simulated wing loading condition were monitored using six multiplexed fiber Bragg grating (FBG) sensors and localized using error outlier based impact localization algorithm. The impact response signals from the FBG sensors were sampled at a rate of 100 kHz using high-speed interrogator. The impacts were localized with an average error of 18.4 mm.

  9. The updated algorithm of the Energy Consumption Program (ECP): A computer model simulating heating and cooling energy loads in buildings (United States)

    Lansing, F. L.; Strain, D. M.; Chai, V. W.; Higgins, S.


    The energy Comsumption Computer Program was developed to simulate building heating and cooling loads and compute thermal and electric energy consumption and cost. This article reports on the new additional algorithms and modifications made in an effort to widen the areas of application. The program structure was rewritten accordingly to refine and advance the building model and to further reduce the processing time and cost. The program is noted for its very low cost and ease of use compared to other available codes. The accuracy of computations is not sacrificed however, since the results are expected to lie within + or - 10% of actual energy meter readings.

  10. Scaling up watershed model parameters: flow and load simulations of the Edisto River Basin, South Carolina, 2007-09 (United States)

    Feaster, Toby D.; Benedict, Stephen T.; Clark, Jimmy M.; Bradley, Paul M.; Conrads, Paul


    hydrologic simulations, a visualization tool (the Edisto River Data Viewer) was developed to help assess trends and influencing variable in the stream ecosystem. Incorporated into the visualization tool were the water-quality load models TOPLOAD, TOPLOAD–H, and LOADEST. Because the focus of this investigation was on scaling up the models from McTier Creek, water-quality concentrations that were previously collected in the McTier Creek Basin were used in the water-quality load models.

  11. Evaluation of bone repair of critical size defects treated with simvastatin-loaded poly(lactic-co-glycolic acid) microspheres in rat calvaria. (United States)

    Ferreira, Lorraine B; Bradaschia-Correa, Vivian; Moreira, Mariana M; Marques, Natasha D M; Arana-Chavez, Victor E


    Statins are hypolipemiant drugs with osteoinductive effect. We evaluated the potential of simvastatin loaded into poly(lactic-co-glycolic acid) (PLGA) microspheres to heal critical size defects in rat calvaria. PLGA scaffolds (50:50 ratio) were synthesized as pure membranes or as microspheres loaded with 2.5% simvastatin. Critical size defects (5-mm diameter) were created in the parietal bone of 3-month-old male Wistar rats; they were either left filled with blood clot (C group), covered with a PLGA membrane (M group) or with PLGA microspheres loaded with simvastatin (MSI group) or not (MM group), and then covered with the PLGA membrane. The defects were evaluated after 30 or 60 days by light and electron microscopy, immunohistochemistry for osteopontin (OPN), bone sialoprotein (BSP) and osteoadherin (OSAD), and immunocytochemistry for OPN. Scanning electron microscopy showed that the calvarial defects treated with MSI were almost completely healed after 60 days, while groups M and C presented less bone formation, whereas the bone matrix formed into the defects of MSI group was more organized and mature. The immunolabeling for OPN and BSP on the matrix in groups C and M showed typical areas of primary bone unlike the MSI that presented weak labeling at the formed area. In the MSI group, there was an intense immunostaining for OSAD in osteoid, as well as in osteocyte cytoplasm. The immunocytochemistry showed intense labeling for OPN with homogeneous distribution in the interfibrillar spaces in all groups after 30 days and after 60 days; however, while C and M groups exhibited similar aspect, the MSI specimens showed weak labeling. The ultrastructural evaluation showed the interaction between the biomaterial and the surrounding tissue where some cells established intimate contact with microspheres. The repair of critical size bone defects was accelerated and enhanced by the implantation of simvastatin-loaded PLGA microspheres. © The Author(s) 2014 Reprints and

  12. Numerical Ductile Tearing Simulation of Circumferential Cracked Pipe Tests under Dynamic Loading Conditions

    Directory of Open Access Journals (Sweden)

    Hyun-Suk Nam


    Full Text Available This paper presents a numerical method to simulate ductile tearing in cracked components under high strain rates using finite element damage analysis. The strain rate dependence on tensile properties and multiaxial fracture strain is characterized by the model developed by Johnson and Cook. The damage model is then defined based on the ductility exhaustion concept using the strain rate dependent multiaxial fracture strain concept. The proposed model is applied to simulate previously published three cracked pipe bending test results under two different test speed conditions. Simulated results show overall good agreement with experimental results.

  13. Numerical ductile tearing simulation of circumferential cracked pipe tests under dynamic loading conditions

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Hyun Suk; Kim, Ji Soo; Ryu, Ho Wan; Kim, Yun Jae [Dept. of Mechanical Engineering, Korea University, Seoul (Korea, Republic of); Kim, Jin Weon [Dept. of Nuclear Engineering, Chosun University, Gwangju (Korea, Republic of)


    This paper presents a numerical method to simulate ductile tearing in cracked components under high strain rates using finite element damage analysis. The strain rate dependence on tensile properties and multiaxial fracture strain is characterized by the model developed by Johnson and Cook. The damage model is then defined based on the ductility exhaustion concept using the strain rate dependent multiaxial fracture strain concept. The proposed model is applied to simulate previously published three cracked pipe bending test results under two different test speed conditions. Simulated results show overall good agreement with experimental results.

  14. Efficient Wideband Numerical Simulations for Nanostructures Employing a Drude-Critical Points (DCP) Dispersive Model. (United States)

    Ren, Qiang; Nagar, Jogender; Kang, Lei; Bian, Yusheng; Werner, Ping; Werner, Douglas H


    A highly efficient numerical approach for simulating the wideband optical response of nano-architectures comprised of Drude-Critical Points (DCP) media (e.g., gold and silver) is proposed and validated through comparing with commercial computational software. The kernel of this algorithm is the subdomain level discontinuous Galerkin time domain (DGTD) method, which can be viewed as a hybrid of the spectral-element time-domain method (SETD) and the finite-element time-domain (FETD) method. An hp-refinement technique is applied to decrease the Degrees-of-Freedom (DoFs) and computational requirements. The collocated E-J scheme facilitates solving the auxiliary equations by converting the inversions of matrices to simpler vector manipulations. A new hybrid time stepping approach, which couples the Runge-Kutta and Newmark methods, is proposed to solve the temporal auxiliary differential equations (ADEs) with a high degree of efficiency. The advantages of this new approach, in terms of computational resource overhead and accuracy, are validated through comparison with well-known commercial software for three diverse cases, which cover both near-field and far-field properties with plane wave and lumped port sources. The presented work provides the missing link between DCP dispersive models and FETD and/or SETD based algorithms. It is a competitive candidate for numerically studying the wideband plasmonic properties of DCP media.

  15. Comparison of Structural Behaviour of Laterally Loaded Pile using Pi Terms and Numerical Simulation (United States)

    Kavitha, P. E.; Beena, K. S.; Narayanan, K. P.


    A set of dimensionless parameters called Pi terms are derived from a set of variables influencing the behaviour of a structural system to represent the behaviour of the system using the principle of similitude. It can be done using Buckingham’s π-theorem or using Rayleigh method. Both the methods derive a set of pi terms which can be used to predict the behaviour of the system under consideration. A structural system of a laterally loaded pile was tested innumerical software, PLAXIS-3D and the results are compared with the predictions using the pi terms. The results are found to be comparable and hence the derived pi terms and the scale factor can be considered represent the laterally loaded pile soil system with a reasonable accuracy.

  16. Numerical Simulation for the Soil-Pile-Structure Interaction under Seismic Loading

    Directory of Open Access Journals (Sweden)

    Lifeng Luan


    Full Text Available Piles are widely used as reinforcement structures in geotechnical engineering designs. If the settlement of the soil is greater than the pile, the pile is pulled down by the soil, and negative friction force is produced. Previous studies have mainly focused on the interaction of pile-soil under static condition. However, many pile projects are located in earthquake-prone areas, which indicate the importance of determining the response of the pile-soil structure under seismic load. In this paper, the nonlinear, explicit, and finite difference program FLAC3D, which considers the mechanical behavior of soil-pile interaction, is used to establish an underconsolidated soil-pile mode. The response processes of the pile side friction force, the pile axial force, and the soil response under seismic load are also analyzed.

  17. Simulation of dynamic traffic loading based on accelerated pavement testing (APT)

    CSIR Research Space (South Africa)

    Steyn, WJvdM


    Full Text Available The objective of this paper is to introduce the latest Heavy Vehicle Simulator (HVS) technology as part of the South African Accelerated Pavement Testing (APT) efforts, its capabilities and expected impact on road pavement analysis....

  18. Load management strategy for Particle-In-Cell simulations in high energy physics

    DEFF Research Database (Denmark)

    Beck, Arnaud; Frederiksen, Jacob Trier; Derouillat, Julien


    In the wake of the intense effort made for the experimental CILEX project, numerical simulation campaigns have been carried out in order to finalize the design of the facility and to identify optimal laser and plasma parameters. These simulations bring, of course, important insight into the funda......In the wake of the intense effort made for the experimental CILEX project, numerical simulation campaigns have been carried out in order to finalize the design of the facility and to identify optimal laser and plasma parameters. These simulations bring, of course, important insight...... into the fundamental physics at play. As a by-product, they also characterize the quality of our theoretical and numerical models. By comparing the results given by different codes, it is possible to point out algorithmic limitations both in terms of physical accuracy and computational performances. In this paper we...... towards a modern, accurate high-performance PIC code for high energy physics....

  19. Finite element simulation of low velocity impact loading on a sandwich composite


    Vishwas M.; Joladarashi Sharnappa; Kulkarni Satyabodh M.


    Sandwich structure offer more advantage in bringing flexural stiffness and energy absorption capabilities in the application of automobile and aerospace components. This paper presents comparison study and analysis of two types of composite sandwich structures, one having Jute Epoxy skins with rubber core and the other having Glass Epoxy skins with rubber core subjected to low velocity normal impact loading. The behaviour of sandwich structure with various parameters such as energy absorption...

  20. Helicopter Slung-Load Simulation Toolbox for Use With MATLAB (Registered trademark) (United States)


    axes include surge , heave and pitch motion, while the lateral axes include heave, sway , roll and yaw motion. The combined axes represent a full...inertia, Size, Attachment locations. There are also fields for the Cable length, Stiffness and Damping . Load types currently supported are box...length, Stiffness and Damping for each cable are set to the same values specified. Once again, it is possible to set these individually, as will be

  1. Sleep restriction and cognitive load affect performance on a simulated marksmanship task. (United States)

    Smith, Carl D; Cooper, Adam D; Merullo, Donna J; Cohen, Bruce S; Heaton, Kristin J; Claro, Pedro J; Smith, Tracey


    Sleep restriction degrades cognitive and motor performance, which can adversely impact job performance and increase the risk of accidents. Military personnel are prone to operating under sleep restriction, and previous work suggests that military marksmanship may be negatively affected under such conditions. Results of these studies, however, are mixed and have often incorporated additional stressors (e.g. energy restriction) beyond sleep restriction. Moreover, few studies have investigated how the degree of difficulty of a marksmanship task impacts performance following sleep restriction. The purpose of the current experiment was to study the effects of sleep restriction on marksmanship while minimizing the potential influence of other forms of stress. A friend-foe discrimination challenge with greater or lesser degrees of complexity (high versus low load) was used as the primary marksmanship task. Active duty Soldiers were recruited, and allowed 2 h of sleep every 24 h over a 72-h testing period. Marksmanship tasks, cognitive assessment metrics and the NASA-Task Load Index were administered daily. Results indicated that reaction times to shoot foe targets and signal friendly targets slowed over time. In addition, the ability to correctly discriminate between friend and foe targets significantly decreased in the high-cognitive-load condition over time despite shot accuracy remaining stable. The NASA-Task Load Index revealed that, although marksmanship performance degraded, participants believed their performance did not change over time. These results further characterize the consequences of sleep restriction on marksmanship performance and the perception of performance, and reinforce the importance of adequate sleep among service members when feasible. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

  2. Verification of turbine and governor model of hydro generator unit for the purpose of load frequency control system simulation

    Directory of Open Access Journals (Sweden)

    Džepčeski Dane


    Full Text Available In this paper, verification of power plant component models is performed by evaluating the deviations between simulation results and test results of the component under study. The obtained deviations of the simulation results from the test results, as well as the acceptability of its value for a particular model and purpose, are determined in the process of verification. In this paper, the test results, the model and the verification procedure are presented. The basis for the model synthesis and verification are the test results derived from measurements conducted with the aim of deriving the operational performance of hydro unit R2 in PSP 'Bajina Bašta' connected to the load frequency control system.

  3. Numerical Simulation of Output Response of PVDF Sensor Attached on a Cantilever Beam Subjected to Impact Loading

    Directory of Open Access Journals (Sweden)

    Cao Vu Dung


    Full Text Available Polyvinylidene Flouride (PVDF is a film-type polymer that has been used as sensors and actuators in various applications due to its mechanical toughness, flexibility, and low density. A PVDF sensor typically covers an area of the host structure over which mechanical stress/strain is averaged and converted to electrical energy. This study investigates the fundamental “stress-averaging” mechanism for dynamic strain sensing in the in-plane mode. A numerical simulation was conducted to simulate the “stress-averaging” mechanism of a PVDF sensor attached on a cantilever beam subjected to an impact loading, taking into account the contribution of piezoelectricity, the cantilever beam’s modal properties, and electronic signal conditioning. Impact tests and FEM analysis were also carried out to verify the numerical simulation results. The results of impact tests indicate the excellent capability of the attached PVDF sensor in capturing the fundamental natural frequencies of the cantilever beam. There is a good agreement between the PVDF sensor’s output voltage predicted by the numerical simulation and that obtained in the impact tests. Parametric studies were conducted to investigate the effects of sensor size and sensor position and it is shown that a larger sensor tends to generate higher output voltage than a smaller one at the same location. However, the effect of sensor location seems to be more significant for larger sensors due to the cancelling problem. Overall, PVDF sensors exhibit excellent sensing capability for in-plane dynamic strain induced by impact loading.

  4. Assessment of long-term knowledge retention following single-day simulation training for uncommon but critical obstetrical events. (United States)

    Vadnais, Mary A; Dodge, Laura E; Awtrey, Christopher S; Ricciotti, Hope A; Golen, Toni H; Hacker, Michele R


    The objectives were to determine (i) whether simulation training results in short-term and long-term improvement in the management of uncommon but critical obstetrical events and (ii) to determine whether there was additional benefit from annual exposure to the workshop. Physicians completed a pretest to measure knowledge and confidence in the management of eclampsia, shoulder dystocia, postpartum hemorrhage and vacuum-assisted vaginal delivery. They then attended a simulation workshop and immediately completed a posttest. Residents completed the same posttests 4 and 12 months later, and attending physicians completed the posttest at 12 months. Physicians participated in the same simulation workshop 1 year later and then completed a final posttest. Scores were compared using paired t-tests. Physicians demonstrated improved knowledge and comfort immediately after simulation. Residents maintained this improvement at 1 year. Attending physicians remained more comfortable managing these scenarios up to 1 year later; however, knowledge retention diminished with time. Repeating the simulation after 1 year brought additional improvement to physicians. Simulation training can result in short-term and contribute to long-term improvement in objective measures of knowledge and comfort level in managing uncommon but critical obstetrical events. Repeat exposure to simulation training after 1 year can yield additional benefits.

  5. Radiographic Analysis of Simulated First Dorsal Interosseous and Opponens Pollicis Loading Upon Thumb CMC Joint Subluxation: A Cadaver Study. (United States)

    Adams, Julie E; O'Brien, Virginia; Magnusson, Erik; Rosenstein, Benjamin; Nuckley, David J


    Therapy programs to treat thumb carpometacarpal (CMC) arthritis may engage selective activation and reeducation of thenar muscles, particularly the first dorsal interosseous (FDI) and opponens pollicis (OP) to reduce subluxation of the joint. We describe the effect of simulated selective activation of the FDI and OP muscles upon radiographic subluxation of the thumb CMC joint. In a cadaver model of CMC subluxation, loads were applied to the FDI, the OP, and then concomitantly at 0%, 25%, 50%, 75%, and 100% maximal loads and radial subluxation of the joint and reduction in subluxation was measured. Selective activation of the OP, alone, improved the subluxation ratio (SR) in a dose-dependent manner. Selective activation of FDI, alone, demonstrated minimal effects on SR. Concomitant activation of OP and FDI improved the SR across all loading states, and activation of 75% and greater, when compared with FDI activation alone, resulted in a statistically significant improvement in SR to within 10% of the presubluxed joint. Concomitant activation of the FDI and OP acts to reduce subluxation of the thumb CMC joint in a dose-dependent fashion. The OP is likely the predominant reducing force. Hand therapy programs that focus on selective strengthening programs likely function in part to encourage patients to activate the easily palpable and easily understood FDI. Concomitant coactivation of the OP may be the major reducing force to elicit clinical and radiographic reduction of subluxation, improved thumb positioning, and reduction of pain and arthritic symptoms.

  6. A comparison of educational strategies for the acquisition of nursing student’s performance and critical thinking: simulation-based training vs. integrated training (simulation and critical thinking strategies

    Directory of Open Access Journals (Sweden)

    Nahid Zarifsanaiey


    Full Text Available Abstract Background There is a need to change the focus of nursing education from traditional teacher-centered training programs to student-centered active methods. The integration of the two active learning techniques will improve the effectiveness of training programs. The objective of this study is to compare the effects of the integrated training (simulation and critical thinking strategies and simulation-based training on the performance level and critical thinking ability of nursing students. Methods The present quasi-experimental study was performed in 2014 on 40 students who were studying practical nursing principles and skills course in the first half of the academic year in Shiraz University of Medical Sciences. Students were randomly divided into control (n = 20 and experimental (n = 20 groups. After training students through simulation and integrated education (simulation and critical thinking strategies, the students' critical thinking ability and performance were evaluated via the use of California Critical Thinking Ability Questionnaire B (CCTST and Objective Structured Clinical Examination (OSCE comprising 10 stations, respectively. The external reliability of the California Critical Thinking questionnaire was reported by Case be between 0.78 and 0.80 and the validity of OSCE was approved by 5 members of the faculty. Furthermore, by using Split Half method (the correlation between odd and even stations, the reliability of the test was approved with correlation coefficient of 0.66. Data were analyzed using t-test and Mann–Whitney test. A significance level of 0.05 was considered to be statistically significant. Results The mean scores of the experimental group performance level were higher than the mean score of the control group performance level. This difference was statistically significant and students in the experimental group in OSCE stations had significantly higher performance than the control group (P <0

  7. Iterative load-balancing method with multigrid level relaxation for particle simulation with short-range interactions (United States)

    Furuichi, Mikito; Nishiura, Daisuke


    We developed dynamic load-balancing algorithms for Particle Simulation Methods (PSM) involving short-range interactions, such as Smoothed Particle Hydrodynamics (SPH), Moving Particle Semi-implicit method (MPS), and Discrete Element method (DEM). These are needed to handle billions of particles modeled in large distributed-memory computer systems. Our method utilizes flexible orthogonal domain decomposition, allowing the sub-domain boundaries in the column to be different for each row. The imbalances in the execution time between parallel logical processes are treated as a nonlinear residual. Load-balancing is achieved by minimizing the residual within the framework of an iterative nonlinear solver, combined with a multigrid technique in the local smoother. Our iterative method is suitable for adjusting the sub-domain frequently by monitoring the performance of each computational process because it is computationally cheaper in terms of communication and memory costs than non-iterative methods. Numerical tests demonstrated the ability of our approach to handle workload imbalances arising from a non-uniform particle distribution, differences in particle types, or heterogeneous computer architecture which was difficult with previously proposed methods. We analyzed the parallel efficiency and scalability of our method using Earth simulator and K-computer supercomputer systems.

  8. Measuring cognitive load during simulation-based psychomotor skills training: sensitivity of secondary-task performance and subjective ratings. (United States)

    Haji, Faizal A; Khan, Rabia; Regehr, Glenn; Drake, James; de Ribaupierre, Sandrine; Dubrowski, Adam


    As interest in applying cognitive load theory (CLT) to the study and design of pedagogic and technological approaches in healthcare simulation grows, suitable measures of cognitive load (CL) are needed. Here, we report a two-phased study investigating the sensitivity of subjective ratings of mental effort (SRME) and secondary-task performance (signal detection rate, SDR and recognition reaction time, RRT) as measures of CL. In phase 1 of the study, novice learners and expert surgeons attempted a visual-monitoring task under two conditions: single-task (monitoring a virtual patient's heart-rate) and dual-task (tying surgical knots on a bench-top simulator while monitoring the virtual patient's heart-rate). Novices demonstrated higher mental effort and inferior secondary-task performance on the dual-task compared to experts (RRT 1.76 vs. 0.73, p = 0.012; SDR 0.27 vs. 0.97, p instructional design research are discussed.

  9. Recent Research and Applications of Numerical Simulation for Dynamic Response of Long-Span Bridges Subjected to Multiple Loads

    Directory of Open Access Journals (Sweden)

    Zhiwei Chen


    Full Text Available Many long-span bridges have been built throughout the world in recent years but they are often subject to multiple types of dynamic loads, especially those located in wind-prone regions and carrying both trains and road vehicles. To ensure the safety and functionality of these bridges, dynamic responses of long-span bridges are often required for bridge assessment. Given that there are several limitations for the assessment based on field measurement of dynamic responses, a promising approach is based on numerical simulation technologies. This paper provides a detailed review of key issues involved in dynamic response analysis of long-span multiload bridges based on numerical simulation technologies, including dynamic interactions between running trains and bridge, between running road vehicles and bridge, and between wind and bridge, and in the wind-vehicle-bridge coupled system. Then a comprehensive review is conducted for engineering applications of newly developed numerical simulation technologies to safety assessment of long-span bridges, such as assessment of fatigue damage and assessment under extreme events. Finally, the existing problems and promising research efforts for the numerical simulation technologies and their applications to assessment of long-span multiload bridges are explored.

  10. Cognitive load in distributed and massed practice in virtual reality mastoidectomy simulation

    DEFF Research Database (Denmark)

    Andersen, Steven Arild Wuyts; Mikkelsen, Peter Trier; Konge, Lars


    -integrated tutoring on CL in virtual reality (VR) mastoidectomy simulation. STUDY DESIGN: Prospective trial. METHODS: Forty novice medical students performed 12 repeated virtual mastoidectomy procedures in the Visible Ear Simulator: 21 completed distributed practice with practice blocks spaced in time and 19....... RESULTS: The mean reaction time increased by 37% during the procedure compared with baseline, demonstrating that the procedure placed substantial cognitive demands. Repeated practice significantly lowered CL in the distributed practice group but not in massed practice group. In addition, CL was found...... to be further increased by 10.3% in the later and more complex stages of the procedure. The simulator-integrated tutor function did not have an impact on CL. CONCLUSION: Distributed practice decreased CL in repeated VR mastoidectomy training more consistently than was seen in massed practice. This suggests...

  11. Computer Simulation and Experimental Study of Deformation in a Radial Tire under Different Static Loads Using Finite Element Method

    Directory of Open Access Journals (Sweden)

    Mir Hamid Reza Ghoreishy


    Full Text Available This research work is devoted to the simulation of a steel-belted radial tire under different static loads. The nonlinear finite element calculations were performed using the MSC.MARC code, installed on a computer system equipped with a parallel processing technology. Hybrid elements in conjunction with two hyperelastic models, namely Marlow and Yeoh, and rebar layer implemented in surface elements were used for the modeling of rubbery and reinforcing parts, respectively. Linear elastic material models were also used for the modeling of the reinforcing elements including steel cord in belts, polyester cord in carcass and nylon cord in cap ply section. Two-dimensional axisymmetric elements were used for the modeling of rim-mounting and inflation and three-dimensional models were developed for the application of the radial, tangential, lateral and torsional loads. Different finite element models were developed, in which both linear and quadratic elements were used in conjunction with different mesh densities in order to find the optimum finite element model. Based on the results of the load deflection (displacement data, the tire stiffness under radial, tangential, lateral and torsional loads were calculated and compared with their corresponding experimentally measured values. The comparison was verified by the accuracy of the measured radial stiffness. However, due to the neglecting of the stiffness in shear and bending modes in cord-rubber composites, modeled with rebar layer methodology, the difference between computed values and real data are not small enough so that a more robust material models and element formulation are required to be developed.

  12. Posterior Tibial Slope Angle Correlates With Peak Sagittal and Frontal Plane Knee Joint Loading During Robotic Simulations of Athletic Tasks. (United States)

    Bates, Nathaniel A; Nesbitt, Rebecca J; Shearn, Jason T; Myer, Gregory D; Hewett, Timothy E


    Tibial slope angle is a nonmodifiable risk factor for anterior cruciate ligament (ACL) injury. However, the mechanical role of varying tibial slopes during athletic tasks has yet to be clinically quantified. To examine the influence of posterior tibial slope on knee joint loading during controlled, in vitro simulation of the knee joint articulations during athletic tasks. Descriptive laboratory study. A 6 degree of freedom robotic manipulator positionally maneuvered cadaveric knee joints from 12 unique specimens with varying tibial slopes (range, -7.7° to 7.7°) through drop vertical jump and sidestep cutting tasks that were derived from 3-dimensional in vivo motion recordings. Internal knee joint torques and forces were recorded throughout simulation and were linearly correlated with tibial slope. The mean (±SD) posterior tibial slope angle was 2.2° ± 4.3° in the lateral compartment and 2.3° ± 3.3° in the medial compartment. For simulated drop vertical jumps, lateral compartment tibial slope angle expressed moderate, direct correlations with peak internally generated knee adduction (r = 0.60-0.65), flexion (r = 0.64-0.66), lateral (r = 0.57-0.69), and external rotation torques (r = 0.47-0.72) as well as inverse correlations with peak abduction (r = -0.42 to -0.61) and internal rotation torques (r = -0.39 to -0.79). Only frontal plane torques were correlated during sidestep cutting simulations. For simulated drop vertical jumps, medial compartment tibial slope angle expressed moderate, direct correlations with peak internally generated knee flexion torque (r = 0.64-0.69) and lateral knee force (r = 0.55-0.74) as well as inverse correlations with peak external torque (r = -0.34 to -0.67) and medial knee force (r = -0.58 to -0.59). These moderate correlations were also present during simulated sidestep cutting. The investigation supported the theory that increased posterior tibial slope would lead to greater magnitude knee joint moments, specifically

  13. New iterative load balancing scheme with multi-grid level relaxation technique toward a large scale geodynamical granular simulation (United States)

    Furuichi, M.; Nishiura, D.


    The complex dynamics of granular system is an essential part of natural processes such as crystal rich magma flow, accretion prism formation or tsunami sedimentation. Numerical modeling with Discrete Element Method (DEM) is an effective approach for understanding granular dynamics especially when the contact between particles induces strongly non-linear rheology (e.g. DEM-CFD simulation for magma reservoir [Bergantz, Nature geo, 2015, Furuichi and Nishiura, G-cubed, 2014]). In Moving Lagrangian particle methods like DEM, a large number of particles is required to obtain an accurate solution. Therefore, an efficient parallelization of the code is important to handle huge particles system on HPC. However, since particles move around during the simulation, the workload between the different MPI processes becomes imbalance when using static sub-domains. To overcome this limitation, we present a new dynamic load balancing algorithms applicable to particle simulation methods such as DEM and Smoothed Particle Hydrodynamics (SPH) [Furuichi and Nishiura submitted to Comput. Phys. Comm.]. Our method utilizes flexible orthogonal domain decomposition in which the domain is divided into columns, each of which independently defines rectangle sub-domains by rows. We regard the difference of the executed time between neighbor logical processes as the residual of nonlinear problem of the domain change. The load balancing is attained by minimizing the residual within the framework of the iterative non-linear solver combined with the multi-grid level technique for the local relaxation. Scalability tests attest that the algorithm demonstrates close-to-optimal strong and weak scalability on the K-computer and the Earth Simulator. This result holds for even as well as uneven particle distribution, including different types of particles and heterogeneous computer architecture. We performed a DEM simulation with over 2 billion particles for demonstrating the proposed scheme. The

  14. Dynamic delamination buckling in composite laminates under impact loading: Computational simulation (United States)

    Grady, Joseph E.; Chamis, Christos C.; Aiello, Robert A.


    A unique dynamic delamination buckling and delamination propagation analysis capability has been developed and incorporated into a finite element computer program. This capability consists of the following: (1) a modification of the direct time integration solution sequence which provides a new analysis algorithm that can be used to predict delamination buckling in a laminate subjected to dynamic loading, and (2) a new method of modeling the composite laminate using plate bending elements and multipoint constraints. This computer program is used to predict both impact induced buckling in composite laminates with initial delaminations and the strain energy release rate due to extension of the delamination. It is shown that delaminations near the outer surface of a laminate are susceptible to local buckling and buckling-induced delamination propagation when the laminate is subjected to transverse impact loading. The capability now exists to predict the time at which the onset of dynamic delamination buckling occurs, the dynamic buckling mode shape, and the dynamic delamination strain energy release rate.

  15. Dynamic delamination buckling in composite laminates under impact loading - Computational simulation (United States)

    Grady, Joseph E.; Chamis, Christos C.; Aiello, Robert A.


    A unique dynamic delamination buckling and delamination propagation analysis capability has been developed and incorporated into a finite element computer program. This capability consists of the following: (1) a modification of the direct time integration solution sequence which provides a new analysis algorithm that can be used to predict delamination buckling in a laminate subjected to dynamic loading, and (2) a new method of modeling the composite laminate using plate bending elements and multipoint constraints. This computer program is used to predict both impact induced buckling in composite laminates with initial delaminations and the strain energy release rate due to extension of the delamination. It is shown that delaminations near the outer surface of a laminate are susceptible to local buckling and buckling-induced delamination propagation when the laminate is subjected to transverse impact loading. The capability now exists to predict the time at which the onset of dynamic delamination buckling occurs, the dynamic buckling mode shape, and the dynamic delamination strain energy release rate.

  16. Computer simulation of yielding supports under static and short-term dynamic load

    Directory of Open Access Journals (Sweden)

    Kumpyak Oleg


    Full Text Available Dynamic impacts that became frequent lately cause large human and economic losses, and their prevention methods are not always effective and reasonable. The given research aims at studying the way of enhancing explosion safety of building structures by means of yielding supports. The paper presents results of numerical studies of strength and deformation property of yielding supports in the shape of annular tubes under static and short-term dynamic loading. The degree of influence of yielding supports was assessed taking into account three peculiar stages of deformation: elastic; elasto-plastic; and elasto-plastic with hardening. The methodology for numerical studies performance was described using finite element analysis with program software Ansys Mechanical v17.2. It was established that rigidity of yielding supports influences significantly their stress-strain state. The research determined that with the increase in deformable elements rigidity dependence between load and deformation of the support in elastic and plastic stages have linear character. Significant reduction of the dynamic response and increase in deformation time of yielding supports were observed due to increasing the plastic component. Therefore, it allows assuming on possibility of their application as supporting units in RC beams.

  17. Quality of computerized blast load simulation for non-linear dynamic ...

    African Journals Online (AJOL)

    Simulation has been carried out using a general-purpose, commercial software system and a special-purpose, blast-specific software product to assess and compare the quality of response prediction of such computational models. Nonlinear dynamic analysis has been performed using a three-dimensional model of a ...

  18. quality of computerized blast load simulation for non-linear dynamic

    African Journals Online (AJOL)


    2005. Simulation has been carried out using a general-purpose, commercial software system and a special-purpose, blast-specific software product to assess and compare the quality of response prediction of such computational models. Nonlinear dynamic analysis has been performed using a three-dimensional model of.

  19. Development of a teicoplanin loading regimen that rapidly achieves target serum concentrations in critically ill patients with severe infections. (United States)

    Nakamura, Atsuo; Takasu, Osamu; Sakai, Yoshiro; Sakamoto, Teruo; Yamashita, Norio; Mori, Shinjiro; Morita, Toshio; Nabeta, Masakazu; Hirayu, Nobuhisa; Yoshiyama, Naomasa; Moroki, Mariko; Tashiro, Keita; Kannae, Mikinori


    We performed high-dose loading (12 mg/kg every 12 h for 48 h; 4 doses total) of teicoplanin (TEIC) in patients with severe methicillin-resistant Staphylococcus aureus (MRSA) infections, with the goal of achieving target serum concentration (TEICc) ≥ 15 mg/l within 48 h of starting administration. The safety and effectiveness of the fixed, early-stage administration method were evaluated across a range of kidney dysfunction severity levels. TEIC high-dose loading was administered to 106 patients with MRSA infection from February 2010 to February 2013. After high-dose loading, maintenance doses based on therapeutic drug monitoring (TDM) of TEICc were administered via 30-min intravenous drips, every 24 h. Subjects were divided into 4 groups based on kidney function and renal replacement therapy (RRT) status for safety and effectiveness evaluation: group 1 (G1) did not undergo RRT and exhibited creatinine clearance (Ccr; ml/min/m(2)) >50, group 2 (G2) exhibited Ccr ≤ 50, group 3 (G3) underwent continuous RRT (CRRT), and group 4 (G4) underwent intermittent RRT (IRRT). TEICc was measured after 24, 48, 72, and 144 h, immediately before TEIC administration. Target TEICc was reached in all groups, and bacteriological effectiveness and utility were high in G1, G2, and G3. The maximum TEICc (≥ 28.0 mg/l) and serum albumin (≤ 1.84 g/dl) were associated with organ toxicity. Fixed high-dose loading of TEIC achieved the target therapeutic range (≥ 15 mg/l) within 48 h of the start of administration regardless of kidney dysfunction, and exhibited sufficient utility. Copyright © 2015 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  20. Observed Temperature Effects on Hourly Residential Electric LoadReduction in Response to an Experimental Critical Peak PricingTariff

    Energy Technology Data Exchange (ETDEWEB)

    Herter, Karen B.; McAuliffe, Patrick K.; Rosenfeld, Arthur H.


    The goal of this investigation was to characterize themanual and automated response of residential customers to high-price"critical" events dispatched under critical peak pricing tariffs testedin the 2003-2004 California Statewide Pricing Pilot. The 15-monthexperimental tariff gave customers a discounted two-price time-of-userate on 430 days in exchange for 27 critical days, during which the peakperiod price (2 p.m. to 7 p.m.) was increased to about three times thenormal time-of-use peak price. We calculated response by five-degreetemperature bins as the difference between peak usage on normal andcritical weekdays. Results indicatedthat manual response to criticalperiods reached -0.23 kW per home (-13 percent) in hot weather(95-104.9oF), -0.03 kW per home (-4 percent) in mild weather (60-94.9oF),and -0.07 kW per home (-9 percent) during cold weather (50-59.9oF).Separately, we analyzed response enhanced by programmable communicatingthermostats in high-use homes with air-conditioning. Between 90oF and94.9oF, the response of this group reached -0.56 kW per home (-25percent) for five-hour critical periods and -0.89 kW/home (-41 percent)for two-hour critical periods.

  1. The EU-strategy against soil acidification. Concept of the critical load; Die EU-Strategie gegen Bodenversauerung. Konzept der kritischen Belastung

    Energy Technology Data Exchange (ETDEWEB)

    Trautwein, W.P.


    The development of so-called `novel forest damages` is considered to be - at least partly - a result of the impact of certain air pollutants such as sulphur and nitrogen oxides; these precipitate as acid rain and acidify the soil, thus damaging sensitive ecosystems, e.g. forests. To combat acidification, the EU Commission has produced a Community strategy, which is based on the concept of critical loads. The DGMK report 548 deals with this concept of critical loads and with the measures to combat soil acidifiction. It explains that critical loads are not damage thresholds, but environmental standards, and deviation does not necessarily required any action. It demonstrates, why the reduction of sulphur dioxide emissions, formed during the utilization of fluid fuels, is not a cost-effective measures. It proposes continued implementation of agreed plans for emission reduction, before additional legislative steps are considered. This report contains information to June 1998 inclusive. (orig.) [Deutsch] Die Entstehung der sogenannten `neuartigen Waldschaeden` fuehrt man zum Teil auf die Einwirkung gewisser Luftschadstoffe wie Schwefel- und Stickoxide zurueck, die als saurer Regen auf die Erde niedergehen und zu einer Versauerung des Bodens und damit zu einer Schaedigung empfindlicher Oekosysteme wie der Waelder fuehren koennen. Die EU-Kommission hat eine Strategie der EU zur Bekaempfung dieser Versauerung entwickelt, die auf dem Konzept der kritischen Belastungen beruht. Der DGMK-Bericht 548 setzt sich mit diesem Konzept der kritischen Belastungen sowie mit den Massnahmen zur Bekaempfung der Bodenversauerung auseinander. Er erlaeutert, dass kritische Belastungen keinen Schwellenwert, sondern einen Umweltstandard darstellen, aus dessen Ueberschreitung nicht zwingend ein Handlungsbedarf abgeleitet werden kann. Er erlaeutert ferner, warum vor allem die Reduktion der Schwefeldioxidemissionen, die beim Einsatz fluessiger Kraft- und Brennstoffe entstehen, keine

  2. Critical loads of acid deposition for wilderness lakes in the sierra nevada (california) estimated by the steady-state water chemistry model


    Shaw, GD; Cisneros, R; Schweizer, D; Sickman, JO; Fenn, ME


    Major ion chemistry (2000-2009) from 208 lakes (342 sample dates and 600 samples) in class I and II wilderness areas of the Sierra Nevada was used in the Steady-State Water Chemistry (SSWC) model to estimate critical loads for acid deposition and investigate the current vulnerability of high elevation lakes to acid deposition. The majority of the lakes were dilute (mean specific conductance=8.0 ?S cm?1) and characterized by low acid neutralizing capacity (ANC; mean= 56.8 ?eq L?1). Two variant...

  3. Extended end-plate connection subjected to monotonic loading: Experimental analysis and FEM simulation (United States)

    Mureşan, Ioana Cristina; Bâlc, Roxana


    This paper presents an experimental investigation of a statically monotonic loaded extended end-plate connection, with preloaded high strength bolts, that was carried out at Laboratory of Faculty of Civil Engineering from Cluj-Napoca. A finite element model using the software package Abaqus [1] was developed in parallel. In order to calibrate the numerical model, the results were analyzed on the basis of moment-rotation curves, stress distribution state and the failure mode of connection. Then, a study was conducted on the numerical model by using a high strength steel (HSS) and changing the stiffness and strength characteristics of some elements. Validation of the numerical modeling was performed against the experimental results and it can be seen that good agreements exist in general.

  4. Taurus II Stage Test Simulations: Using Large-Scale CFD Simulations to Provide Critical Insight into Plume Induced Environments During Design (United States)

    Struzenberg, L. L.; West, J. S.


    This paper describes the use of targeted Loci/CHEM CFD simulations to evaluate the effects of a dual-engine first-stage hot-fire test on an evolving integrated launch pad/test article design. This effort was undertaken as a part of the NESC Independent Assessment of the Taurus II Stage Test Series. The underlying conceptual model included development of a series of computational models and simulations to analyze the plume induced environments on the pad, facility structures and test article. A pathfinder simulation was first developed, capable of providing quick-turn around evaluation of plume impingement pressures on the flame deflector. Results from this simulation were available in time to provide data for an ongoing structural assessment of the deflector. The resulting recommendation was available in a timely manner and was incorporated into construction schedule for the new launch stand under construction at Wallops Flight Facility. A series of Reynolds-Averaged Navier-Stokes (RANS) quasi-steady simulations representative of various key elements of the test profile was performed to identify potential concerns with the test configuration and test profile. As required, unsteady Hybrid-RANS/LES simulations were performed, to provide additional insight into critical aspects of the test sequence. Modifications to the test-specific hardware and facility structures thermal protection as well as modifications to the planned hot-fire test profile were implemented based on these simulation results.

  5. A Simulation of Information Load and Its Affect on Tactical Decision Making (United States)


    26 IV. THE COHEN, MARCH AND OLSEN MODEL : THE GARBAGE CAN ------------------------------------- 33 V. INFORMATION: ITS NATURE...theorists. ll The Cohen, March , and Olsen " Garbage Can" model will be presented in Charter ?/. It will be presented with an explanation which permits an...Cohen, March , and Olsen for use in the " Garbage Can" model and its accompanying simulation, including: 42 1. Unsegmented participation: This structure

  6. The effect of implementing cognitive load theory-based design principles in virtual reality simulation training of surgical skills: a randomized controlled trial. (United States)

    Andersen, Steven Arild Wuyts; Mikkelsen, Peter Trier; Konge, Lars; Cayé-Thomasen, Per; Sørensen, Mads Sølvsten


    Cognitive overload can inhibit learning, and cognitive load theory-based instructional design principles can be used to optimize learning situations. This study aims to investigate the effect of implementing cognitive load theory-based design principles in virtual reality simulation training of mastoidectomy. Eighteen novice medical students received 1 h of self-directed virtual reality simulation training of the mastoidectomy procedure randomized for standard instructions (control) or cognitive load theory-based instructions with a worked example followed by a problem completion exercise (intervention). Participants then completed two post-training virtual procedures for assessment and comparison. Cognitive load during the post-training procedures was estimated by reaction time testing on an integrated secondary task. Final-product analysis by two blinded expert raters was used to assess the virtual mastoidectomy performances. Participants in the intervention group had a significantly increased cognitive load during the post-training procedures compared with the control group (52 vs. 41 %, p  = 0.02). This was also reflected in the final-product performance: the intervention group had a significantly lower final-product score than the control group (13.0 vs. 15.4, p  Increased cognitive load when part tasks needed to be integrated in the post-training procedures could be a possible explanation for this. Other instructional designs and methods are needed to lower the cognitive load and improve the performance in virtual reality surgical simulation training of novices.

  7. Combination of inquiry learning model and computer simulation to improve mastery concept and the correlation with critical thinking skills (CTS) (United States)

    Nugraha, Muhamad Gina; Kaniawati, Ida; Rusdiana, Dadi; Kirana, Kartika Hajar


    Among the purposes of physics learning at high school is to master the physics concepts and cultivate scientific attitude (including critical attitude), develop inductive and deductive reasoning skills. According to Ennis et al., inductive and deductive reasoning skills are part of critical thinking. Based on preliminary studies, both of the competence are lack achieved, it is seen from student learning outcomes is low and learning processes that are not conducive to cultivate critical thinking (teacher-centered learning). One of learning model that predicted can increase mastery concepts and train CTS is inquiry learning model aided computer simulations. In this model, students were given the opportunity to be actively involved in the experiment and also get a good explanation with the computer simulations. From research with randomized control group pretest-posttest design, we found that the inquiry learning model aided computer simulations can significantly improve students' mastery concepts than the conventional (teacher-centered) method. With inquiry learning model aided computer simulations, 20% of students have high CTS, 63.3% were medium and 16.7% were low. CTS greatly contribute to the students' mastery concept with a correlation coefficient of 0.697 and quite contribute to the enhancement mastery concept with a correlation coefficient of 0.603.

  8. Prospective randomized crossover study of simulation vs. didactics for teaching medical students the assessment and management of critically ill patients. (United States)

    McCoy, Christopher Eric; Menchine, Michael; Anderson, Craig; Kollen, Robert; Langdorf, Mark I; Lotfipour, Shahram


    Simulation (SIM) allows medical students to manage high-risk/low-frequency cases in an environment without patient risk. However, evidence for the efficacy of SIM-based training remains limited. To compare SIM-based training to traditional didactic lecture (LEC) for teaching medical students to assess and manage critically ill patients with myocardial infarction (MI) and anaphylaxis. Prospective, randomized, non-blinded crossover study of 28 fourth-year medical students. Students were oriented to the human patient simulator, then randomized to SIM or LEC between August and December 2007. The SIM group learned to manage MI using SIM training and the LEC group learned via PowerPoint lecture. All subjects' assessment and management skills were then evaluated during a simulation session of MI. During a second instruction session, the students crossed over and were taught anaphylaxis using the opposite modality and similar assessments were conducted. Completion of critical actions for each case were scored, converted to percentages, and analyzed via signed rank test. Of 28 subjects, 27 performed better when trained with SIM compared with LEC (p didactic lecture for teaching fourth-year medical students to assess and manage simulated critically ill MI and anaphylaxis patients. Copyright © 2011 Elsevier Inc. All rights reserved.

  9. Numerical simulation of wave propagation and snow failure from explosive loading

    CERN Document Server

    Sidler, Rolf; Dual, Jürg; Schweizer, Jürg


    Avalanche control by explosion is a widely applied method to minimize the avalanche risk to infrastructure in snow-covered mountain areas. However, the mechanisms involved leading from an explosion to the release of an avalanche are not well understood. Here we test the hypothesis that weak layers fail due to the stress caused by propagating acoustic waves. The underlying mechanism is that the stress induced by the acoustic waves exceeds the strength of the snow layers. We compare field measurements to a numerical simulation of acoustic wave propagation in a porous material. The simulation consists of an acoustic domain for the air above the snowpack and a poroelastic domain for the dry snowpack. The two domains are connected by a wave field decomposition and open pore boundary conditions. Empirical relations are used to derive a porous model of the snowpack from density profiles of the field experiment. Biot's equations are solved in the poroelastic domain to obtain simulated accelerations in the snowpack an...

  10. Circuit simulations of the use of explosive formed fuses to obtain high voltage pulses for high impedance loads

    Energy Technology Data Exchange (ETDEWEB)

    Degnan, J.H.; Kiuttu, G.F.; Turchi, P.J. [Air Force Research Labs., Kirtland AFB, NM (United States). Phillips Research Site; Graham, J.D. [Maxwell Technologies, Inc., Albuquerque, NM (United States); Goforth, J.H.; Oona, H.; Lopez, E.A. [Los Alamos National Lab., NM (United States)


    Explosive Formed Fuses (EFF`s) use conducting elements that are deformed by explosive pressure (typically, against dielectric dies). This causes the fuse geometry to change, so that the conducting element cross section decreases. This enables a higher ratio of current conduction to current interrupt time than for normal fuses, and it enables more control of when current interruption occurs. In combination with a suitable output closing switch, EFF`s can be used to obtain several hundred kilovolt voltage pulses from inductive stores to drive several ohm loads. With proper choices of inductive store, EFF geometry and material, and output closing switch features, such a voltage pulse can be approximately flat topped for microsecond duration, and have a small fraction of microsecond risetime. The authors present theoretical analysis and circuit simulations which illustrate this, using scaled empirical EFF parameters, for inductive stores in the 1 Weber flux, several hundred nanohenry range. The circuit simulations were done using Microcap-4, with user defined elements. These simulations were done with static inductive stores, and with explosive magnetic flux compression generators driving inductive stores.

  11. Analysis and Testing of Load Characteristics for Rotary-Percussive Drilling of Lunar Rock Simulant with a Lunar Regolith Coring Bit

    Directory of Open Access Journals (Sweden)

    Peng Li


    Full Text Available Based on an optimized lunar regolith coring bit (LRCB configuration, the load characteristics of rotary-percussive drilling of lunar rock simulant in a laboratory environment are analyzed to determine the effects of the drilling parameters (the rotational velocity, the penetration rate, and the percussion frequency on the drilling load. The process of rotary drilling into lunar rock using an LRCB is modeled as an interaction between an elemental blade and the rock. The rock’s fracture mechanism during different stages of the percussive mechanism is analyzed to create a load forecasting model for the cutting and percussive fracturing of rock using an elemental blade. Finally, a model of the load on the LRCB is obtained from the analytic equation for the bit’s cutting blade distribution; experimental verification of the rotary-impact load characteristics for lunar rock simulant with different parameters is performed. The results show that the penetrations per revolution (PPR are the primary parameter influencing the drilling load. When the PPR are fixed, increasing the percussion frequency reduces the drilling load on the rock. Additionally, the variation pattern of the drilling load of the bit is in agreement with that predicted by the theoretical model. This provides a research basis for subsequent optimization of the drilling procedure and online recognition of the drilling process.

  12. Spatial electric load forecasting

    CERN Document Server

    Willis, H Lee


    Spatial Electric Load Forecasting Consumer Demand for Power and ReliabilityCoincidence and Load BehaviorLoad Curve and End-Use ModelingWeather and Electric LoadWeather Design Criteria and Forecast NormalizationSpatial Load Growth BehaviorSpatial Forecast Accuracy and Error MeasuresTrending MethodsSimulation Method: Basic ConceptsA Detailed Look at the Simulation MethodBasics of Computerized SimulationAnalytical Building Blocks for Spatial SimulationAdvanced Elements of Computerized SimulationHybrid Trending-Simulation MethodsAdvanced

  13. Biomechanical modeling and load-carrying simulation of lower limb exoskeleton. (United States)

    Zhu, Yanhe; Zhang, Guoan; Zhang, Chao; Liu, Gangfeng; Zhao, Jie


    This paper introduces novel modern equipment-a lower extremity exoskeleton, which can implement the mutual complement and the interaction between human intelligence and the robot's mechanical strength. In order to provide a reference for the exoskeleton structure and the drive unit, the human biomechanics were modeled and analyzed by LifeModeler and Adams software to derive each joint kinematic parameter. The control was designed to implement the zero-force interaction between human and exoskeleton. Furthermore, simulations were performed to verify the control and assist effect. In conclusion, the system scheme of lower extremity exoskeleton is demonstrated to be feasible.

  14. Particle-in-cell simulations of the critical ionization velocity effect in finite size clouds (United States)

    Moghaddam-Taaheri, E.; Lu, G.; Goertz, C. K.; Nishikawa, K. - I.


    The critical ionization velocity (CIV) mechanism in a finite size cloud is studied with a series of electrostatic particle-in-cell simulations. It is observed that an initial seed ionization, produced by non-CIV mechanisms, generates a cross-field ion beam which excites a modified beam-plasma instability (MBPI) with frequency in the range of the lower hybrid frequency. The excited waves accelerate electrons along the magnetic field up to the ion drift energy that exceeds the ionization energy of the neutral atoms. The heated electrons in turn enhance the ion beam by electron-neutral impact ionization, which establishes a positive feedback loop in maintaining the CIV process. It is also found that the efficiency of the CIV mechanism depends on the finite size of the gas cloud in the following ways: (1) Along the ambient magnetic field the finite size of the cloud, L (sub parallel), restricts the growth of the fastest growing mode, with a wavelength lambda (sub m parallel), of the MBPI. The parallel electron heating at wave saturation scales approximately as (L (sub parallel)/lambda (sub m parallel)) (exp 1/2); (2) Momentum coupling between the cloud and the ambient plasma via the Alfven waves occurs as a result of the finite size of the cloud in the direction perpendicular to both the ambient magnetic field and the neutral drift. This reduces exponentially with time the relative drift between the ambient plasma and the neutrals. The timescale is inversely proportional to the Alfven velocity. (3) The transvers e charge separation field across the cloud was found to result in the modulation of the beam velocity which reduces the parallel heating of electrons and increases the transverse acceleration of electrons. (4) Some energetic electrons are lost from the cloud along the magnetic field at a rate characterized by the acoustic velocity, instead of the electron thermal velocity. The loss of energetic electrons from the cloud seems to be larger in the direction of

  15. Steady-state and dynamic evaluation of the electric propulsion system test bed vehicle on a road load simulator (United States)

    Dustin, M. O.


    The propulsion system of the Lewis Research Center's electric propulsion system test bed vehicle was tested on the road load simulator under the DOE Electric and Hybrid Vehicle Program. This propulsion system, consisting of a series-wound dc motor controlled by an infinitely variable SCR chopper and an 84-V battery pack, is typical of those used in electric vehicles made in 1976. Steady-state tests were conducted over a wide range of differential output torques and vehicle speeds. Efficiencies of all of the components were determined. Effects of temperature and voltage variations on the motor and the effect of voltage changes on the controller were examined. Energy consumption and energy efficiency for the system were determined over the B and C driving schedules of the SAE J227a test procedure.

  16. Atmospheric influences on water quality: a simulation of nutrient loading for the Pearl River Basin, USA. (United States)

    Joyner, Timothy Andrew; Rohli, Robert V


    Knowledge of water quality conditions is essential in assessing the health of riverine ecosystems. The goal of this study is to determine the degree to which water quality variables are related to precipitation and air temperature conditions for a segment of the Pearl River Basin near Bogalusa, LA, USA. The AQUATOX ecological fate simulation model is used to estimate daily total nitrogen, total phosphorus, and dissolved oxygen concentrations over a 2-year period. Daily modeled output for each variable was calibrated against reliably measured data to assess the accuracy. Observed data were plotted against simulated data for controlled and perturbed models for validation, and stepwise multiple regression analysis was used to quantify the relationships between the water quality and meteorological variables. Results suggest that daily dissolved oxygen is significantly negatively correlated to concurrent daily mean air temperature with a total explained variance of 0.679 (p water quality in the Pearl Basin. Therefore, environmental planners should expect that future climatic changes are likely to alter water quality.

  17. CFD simulation on critical heat flux of flow boiling in IVR-ERVC of a nuclear reactor

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiang, E-mail: [State Nuclear Power Technology Research & Development Center, South Area, Future Science and Technology Park, Chang Ping District, Beijing 102209 (China); Hu, Teng [State Nuclear Power Technology Research & Development Center, South Area, Future Science and Technology Park, Chang Ping District, Beijing 102209 (China); Chen, Deqi, E-mail: [Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Chongqing University, 400044 (China); Zhong, Yunke; Gao, Hong [Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Chongqing University, 400044 (China)


    Highlights: • CFD simulation on CHF of boiling two-phase flow in ERVC is proposed. • CFD simulation result of CHF agrees well with that of experimental result. • The characteristics of boiling two-phase flow and boiling crisis are analyzed. - Abstract: The effectiveness of in-vessel retention (IVR) by external reactor vessel cooling (ERVC) strongly depends on the critical heat flux (CHF). As long as the local CHF does not exceed the local heat flux, the lower head of the pressure vessel can be cooled sufficiently to prevent from failure. In this paper, a CFD simulation is carried out to investigate the CHF of ERVC. This simulation is performed by a CFD code fluent couple with a boiling model by UDF (User-Defined Function). The experimental CHF of ERVC obtained by State Nuclear Power Technology Research and Development Center (SNPTRD) is used to validate this CFD simulation, and it is found that the simulation result agrees well with the experimental result. Based on the CFD simulation, detailed analysis focusing on the pressure distribution, velocity distribution, void fraction distribution, heating wall temperature distribution are proposed in this paper.

  18. The Simulation Calculations And Dielectric Characteristics Investigation of a Hybrid Dielectric-Iris-Loaded Travelling Accelerating Structure

    CERN Document Server

    Wu, C F


    Mafia code has been used to calculate the RF properties versus the geometric parameters and dielectric permittivity of the X-band (f=9.37 GHz) hybrid dielectric-iris-loaded travelling accelerating structure. The simulation results show that when the range of the permittivity is about 5–9 and the geometric parameters are optimized, the new structure may have lower ratio (about 1) of peak surface electric field at the iris to axial accelerating electric field , while r, Q, r/Q of the new structure being comparable to iris-loaded accelerating structure. The experimental investigation of the permittivity of the dielectric (ceramic)has been made by using the cavity perturbation technique. The results show that the permittivity of the ceramic is about 5.8 at the X-band and its stability is good.The above results will be applied to the design of the new accelerating structure, which may be a potential candidate of high gradient Linear accelerator.

  19. Numerical simulation of large-scale bed load particle tracer advection-dispersion in rivers with free bars (United States)

    Iwasaki, Toshiki; Nelson, Jonathan M.; Shimizu, Yasuyuki; Parker, Gary


    Asymptotic characteristics of the transport of bed load tracer particles in rivers have been described by advection-dispersion equations. Here we perform numerical simulations designed to study the role of free bars, and more specifically single-row alternate bars, on streamwise tracer particle dispersion. In treating the conservation of tracer particle mass, we use two alternative formulations for the Exner equation of sediment mass conservation: the flux-based formulation, in which bed elevation varies with the divergence of the bed load transport rate, and the entrainment-based formulation, in which bed elevation changes with the net deposition rate. Under the condition of no net bed aggradation/degradation, a 1-D flux-based deterministic model that does not describe free bars yields no streamwise dispersion. The entrainment-based 1-D formulation, on the other hand, models stochasticity via the probability density function (PDF) of particle step length, and as a result does show tracer dispersion. When the formulation is generalized to 2-D to include free alternate bars, however, both models yield almost identical asymptotic advection-dispersion characteristics, in which streamwise dispersion is dominated by randomness inherent in free bar morphodynamics. This randomness can result in a heavy-tailed PDF of waiting time. In addition, migrating bars may constrain the travel distance through temporary burial, causing a thin-tailed PDF of travel distance. The superdiffusive character of streamwise particle dispersion predicted by the model is attributable to the interaction of these two effects.

  20. Simulation Study of Inertial Micro-Switch as Influenced by Squeeze-Film Damping and Applied Acceleration Load

    Directory of Open Access Journals (Sweden)

    Yingchun Peng


    Full Text Available Squeeze-film damping and acceleration load are two major issues in the design of inertial micro-switches. In order to deeply and systematically study these two issues, this paper proposes a typical vertically-driven inertial micro-switch, wherein the air and electrode gaps were chosen to design the required damping ratio and threshold value, respectively. The switch was modeled by ANSYS Workbench, and the simulation program was optimized for computational accuracy and speed. Transient analysis was employed to investigate the relationship between the damping ratio, acceleration load, and the natural frequency, and the dynamic properties (including contact bounce, contact time, response time, and threshold acceleration of the switch. The results can be used as a guide in the design of inertial micro-switches to meet various application requirements. For example, increasing the damping ratio can prolong the contact time of the switch activated by short acceleration duration or reduce the contact bounce of the switch activated by long acceleration duration; the threshold value is immune to variations in the damping effect and acceleration duration when the switch is quasi-statically operated; the anti-jamming capability of the switch can be improved by designing the sensing frequency of the switch to be higher than the acceleration duration but much lower than the other order frequencies of the switch.

  1. Atomistic computer simulations on multi-loaded PAMAM dendrimers: a comparison of amine- and hydroxyl-terminated dendrimers (United States)

    Badalkhani-Khamseh, Farideh; Ebrahim-Habibi, Azadeh; Hadipour, Nasser L.


    Poly(amidoamine) (PAMAM) dendrimers have been extensively studied as delivery vectors in biomedical applications. A limited number of molecular dynamics (MD) simulation studies have investigated the effect of surface chemistry on therapeutic molecules loading, with the aim of providing insights for biocompatibility improvement and increase in drug loading capacity of PAMAM dendrimers. In this work, fully atomistic MD simulations were employed to study the association of 5-Fluorouracil (5-FU) with amine (NH2)- and hydroxyl (OH)-terminated PAMAM dendrimers of generations 3 and 4 (G3 and G4). MD results show a 1:12, 1:1, 1:27, and 1:4 stoichiometry, respectively, for G3NH2-FU, G3OH-FU, G4NH2-FU, and G4OH-FU complexes, which is in good agreement with the isothermal titration calorimetry results. The results obtained showed that NH2-terminated dendrimers assume segmented open structures with large cavities and more drug molecules can encapsulate inside the dendritic cavities of amine terminated dendrimers. However, OH-terminated have a densely packed structure and therefore, 5-FU drug molecules are more stable to locate close to the surface of the dendrimers. Intermolecular hydrogen bonding analysis showed that 5-FU drug molecules have more tendency to form hydrogen bonds with terminal monomers of OH-terminated dendrimers, while in NH2-terminated these occur both in the inner region and the surface. Furthermore, MM-PBSA analysis revealed that van der Waals and electrostatic energies are both important to stabilize the complexes. We found that drug molecules are distributed uniformly inside the amine and hydroxyl terminated dendrimers and therefore, both dendrimers are promising candidates as drug delivery systems for 5-FU drug molecules.

  2. A full-scale PC-based load-flow simulator for a training of the electric power systems` dispatching personnel

    Energy Technology Data Exchange (ETDEWEB)

    Tarasov, V.I.; Novokshonov, O.G. [State Technical Univ., Irkutsk (Russian Federation)


    The simulator, described in the paper, is a complex pseudo-dynamic simulator, which realizes all functions both of the load-flow and the operational switching simulators and is designed for teaching, training and checking the skills and knowledge of a dispatching personnel of electric power systems and electric nets. The simulator uses a full-scale power system mathematical model, which is described by a system of non-linear equations in the form of the node power matches. System frequency, node voltage moduli and node voltage angles are regarded as variables. The simulator takes into account frequency changes and actions of all protection devices. It also controls the acceptability for voltage levels, the transmission power transfer, and the current loads of all system elements. 8 refs

  3. Comparative study on deformation and mechanical behavior of corroded pipe: Part I–Numerical simulation and experimental investigation under impact load

    Directory of Open Access Journals (Sweden)

    Dong-Man Ryu


    Full Text Available Experiments and a numerical simulation were conducted to investigate the deformation and impact behavior of a corroded pipe, as corrosion, fatigue, and collision phenomena frequently occur in subsea pipelines. This study focuses on the deformation of the corrosion region and the variation of the geometry of the pipe under impact loading. The experiments for the impact behavior of the corroded pipe were performed using an impact test apparatus to validate the results of the simulation. In addition, during the simulation, material tests were performed, and the results were applied to the simulation. The ABAQUS explicit finite element analysis program was used to perform numerical simulations for the parametric study, as well as experiment scenarios, to investigate the effects of defects under impact loading. In addition, the modified ASME B31.8 code formula was proposed to define the damage range for the dented pipe.

  4. Experiment and Simulation Study on the Special Phase Behavior of Huachang Near-Critical Condensate Gas Reservoir Fluid

    Directory of Open Access Journals (Sweden)

    Dali Hou


    Full Text Available Due to the special phase behavior of near-critical fluid, the development approaches of near-critical condensate gas and near-critical volatile oil reservoirs differ from conventional oil and gas reservoirs. In the near-critical region, slightly reduced pressure may result in considerable change in gas and liquid composition since a large amount of gas or retrograde condensate liquid is generated. It is of significance to gain insight into the composition variation of near-critical reservoir during the depletion development. In our study, we performed a series of PVT experiments on a real near-critical gas condensate reservoir fluid. In addition to the experimental studies, a commercial simulator combined with the PREOS model was utilized to study retrograde condensate characteristics and reevaporation mechanism of condensate oil with CO2 injection based on vapor-liquid phase equilibrium thermodynamic theory. The research shows that when reservoir pressure drops below a certain pressure, the variation of retrograde condensate liquid saturation of the residual reservoir fluid exhibits the phase behavior of volatile oil.

  5. Application of a Loading Dose of Colistin Methanesulfonate in Critically Ill Patients: Population Pharmacokinetics, Protein Binding, and Prediction of Bacterial Kill (United States)

    Karaiskos, Ilias; Plachouras, Diamantis; Karvanen, Matti; Pontikis, Konstantinos; Jansson, Britt; Papadomichelakis, Evangelos; Antoniadou, Anastasia; Giamarellou, Helen; Armaganidis, Apostolos; Cars, Otto; Friberg, Lena E.


    A previous pharmacokinetic study on dosing of colistin methanesulfonate (CMS) at 240 mg (3 million units [MU]) every 8 h indicated that colistin has a long half-life, resulting in insufficient concentrations for the first 12 to 48 h after initiation of treatment. A loading dose would therefore be beneficial. The aim of this study was to evaluate CMS and colistin pharmacokinetics following a 480-mg (6-MU) loading dose in critically ill patients and to explore the bacterial kill following the use of different dosing regimens obtained by predictions from a pharmacokinetic-pharmacodynamic model developed from an in vitro study on Pseudomonas aeruginosa. The unbound fractions of colistin A and colistin B were determined using equilibrium dialysis and considered in the predictions. Ten critically ill patients (6 males; mean age, 54 years; mean creatinine clearance, 82 ml/min) with infections caused by multidrug-resistant Gram-negative bacteria were enrolled in the study. The pharmacokinetic data collected after the first and eighth doses were analyzed simultaneously with the data from the previous study (total, 28 patients) in the NONMEM program. For CMS, a two-compartment model best described the pharmacokinetics, and the half-lives of the two phases were estimated to be 0.026 and 2.2 h, respectively. For colistin, a one-compartment model was sufficient and the estimated half-life was 18.5 h. The unbound fractions of colistin in the patients were 26 to 41% at clinical concentrations. Colistin A, but not colistin B, had a concentration-dependent binding. The predictions suggested that the time to 3-log-unit bacterial kill for a 480-mg loading dose was reduced to half of that for the dose of 240 mg. PMID:22615285

  6. Simulation in Medical Education: Focus on Anesthesiology and Critical Care Medicine

    Directory of Open Access Journals (Sweden)

    D. John Doyle


    Full Text Available Simulation refers to the artificial representation of a complex real-world process with sufficient fidelity to achieve a particular objective, usually for the purposes of training or performance testing. While simulation has been important from early times (as in the rehearsal of animal hunting activities or preparing for warfare, the needs of World War II greatly accelerated simulation technology for use in flight training. With the available of inexpensive computer technology in recent years, simulation technology has blossomed again, especially in the field of medicine, where applications range from scientific modeling to clinical performance appraisal in the setting of crisis management.

  7. Simulation of the Radiative Impact of High Dust Loading during a Dust Storm in March 2012 (United States)

    Puthan Purakkal, J.; Kalenderski, S.; Stenchikov, G. L.


    We investigated a severe dust storm that developed over vast areas of the Middle East on 18-19 March 2012 and affected Saudi Arabia, Sudan, Egypt, Jordan, United Arab Emirates, Bahrain, Qatar, Oman, Kuwait, Iraq, Iran, Israel, and Pakistan. The visible aerosol optical depth recorded by the AERONET station on the KAUST campus (22.30o N 39.10o E) during the storm reached 4.5, exceeding the average level by an order of magnitude. To quantify the effects of the dust on atmospheric radiation and dynamics, we analyzed available ground-based and satellite observations and conducted numerical simulations using a fully coupled meteorology-chemistry-aerosol model (WRF-Chem). The model was able to reproduce the spatial and temporal patterns of the aerosol optical depths (AOD) observed by airborne and ground-based instruments. The major dust sources included river valleys of lower Tigris and Euphrates in Iraq, desert areas in Kuwait, Iran, United Arab Emirates, central Arabia including Rub' al Khali, An Nafud, and Ad Dahna, as well as the Red Sea coast of the Arabian Peninsula. The total amount of dust generated across the entire domain during the period of the simulation reached 93.76 Mt; 73.04 Mt of dust was deposited within the domain; 6.56 Mt of dust sunk in the adjacent sea waters, including 1.20 Mt that sedimented into the Red Sea. The model predicted a well-mixed boundary layer expanding up to 3.5 km in the afternoon. Some dust plumes were seen above the Planetary Boundary layer. In our simulations, mineral dust heated the lower atmosphere with a maximum heating rate of 9 K/day. The dust storm reduced the downwelling shortwave radiation at the surface to a maximum daily average value of -134 Wm-2 and the daily averaged long-wave forcing at the surface increased to 43 Wm-2. The combined short-wave cooling and long-wave warming effects of dust aerosols caused significant reduction in the surface air temperature -6.7 K at 1200 UTC on 19 March 2013.

  8. Influence of hydraulic loading rate, simulated storm events and seasonality on the treatment performance of an experimental three-stage hybrid constructed wetland system


    Ávila Martín, Cristina; García Serrano, Joan; Garfi, Marianna


    An experimental hybrid system based on an anaerobic reactor followed by three stages of different constructed wetland configurations was evaluated when operating under a high hydraulic loading rate (HLR = 0.27 m d-1, considering the area of the VF beds) for one year, which corresponds to four times the nominal hydraulic loading rate, with the purpose of reducing the specific area required. Moreover, in order to assess its buffer capacity, a major storm event was simulated by increasing the HL...

  9. Loads in the design of flight vehicles

    Directory of Open Access Journals (Sweden)

    Simion TĂTARU


    Full Text Available The calculation of flight loads is a critical part of air vehicle design. On the other hand, the prediction of accurate loads is a sophisticated and complex process that requires skilled and experienced engineers. They must integrate results from wind tunnel tests, computer simulations, historical data and empirical formulations into a number of loads cases that provide a realistic assessment of the flight vehicle’s environment. Under these conditions, the vehicle must satisfy requirements imposed by regulatory agencies as part of the vehicle certification process.Loads and boundary conditions can be associated to either the finite element model or the underlying geometry. By associating loads and boundary conditions to the geometry the finite element model mesh and elements can be modified without redefining and applying the loads to the model. Loads and boundary conditions are associated to the model geometry by default.

  10. Effects of Using Human Patient Simulator (HPS?) versus a CD-ROM on Cognition and Critical Thinking


    Johnson, Don; Flagg, Amanda; Dremsa, Theresa L.


    Background: Very little prospective randomized experimental research exists on the use of simu­lation as a teaching method, and no studies have compared the two strategies of using the HPS? and a CD-ROM. In addition, no researchers have investigated the effects of simulation on various levels of cognition, specifically lower-level and higher-level cognition or critical thinking. Objectives: A prospective pretest-posttest experimental mixed design (within and between) was used to determine if...

  11. Numerical simulation of aerothermal loads in hypersonic engine inlets due to shock impingement (United States)

    Ramakrishnan, R.


    The effect of shock impingement on an axial corner simulating the inlet of a hypersonic vehicle engine is modeled using a finite-difference procedure. A three-dimensional dynamic grid adaptation procedure is utilized to move the grids to regions with strong flow gradients. The adaptation procedure uses a grid relocation stencil that is valid at both the interior and boundary points of the finite-difference grid. A linear combination of spatial derivatives of specific flow variables, calculated with finite-element interpolation functions, are used as adaptation measures. This computational procedure is used to study laminar and turbulent Mach 6 flows in the axial corner. The description of flow physics and qualitative measures of heat transfer distributions on cowl and strut surfaces obtained from the analysis are compared with experimental observations. Conclusions are drawn regarding the capability of the numerical scheme for enhanced modeling of high-speed compressible flows.

  12. Numerical simulation of progressive debonding in fiber reinforced composite under transverse loading

    DEFF Research Database (Denmark)

    Kushch, V.; Shmegera, S.V.; Brøndsted, Povl


    The finite element model of progressive debonding in fiber reinforced composite is developed based on the cohesive-zone model of interface. An interface crack nucleation, onset and growth have been studied in detail for a single fiber and comparison is made with the linear fracture mechanics model....... Then, the effect on debonding progress of local stress redistribution due to interaction between the fibers was studied in the framework of two-inclusion model. Simulation of progressive debonding in fiber reinforced composite using the many-fiber models of composite has been performed. It has been...... shown that the developed model provides detailed analysis of the progressive debonding phenomenon including the interface crack cluster formation, overall stiffness reduction and induced anisotropy of the effective elastic moduli of composite....

  13. Simulation of performance of circular CFST columns under short-time and long-time load

    Directory of Open Access Journals (Sweden)

    Vatulia Glib


    Full Text Available The method of calculation of concrete-filled steel tubular (CFST columns with consideration of physical nonlinearity of materials, geometric nonlinearity of the confinement and the effect of the gain in strength of the core is considered. The method uses a step iteration algorithm, which involves analytical dependencies and the ultimate element simulation method. Allowance for creep of concrete is based on using the generalized kinetic long-term deformation curve and phenomenological deformation development equations. Creep of concrete is controlled through new structural factors that determine the structure of cement rock layers between sand and mortar grains between chip grains. The method is validated by comparing experimental results and theoretical data. The suggested method allowed to study the stress-strain and limit state of circular concrete-filled steel tubular columns, as well as to evaluate their effectiveness with account for the time factor.

  14. The impact of critical event checklists on medical management and teamwork during simulated crises in a surgical daycare facility. (United States)

    Everett, T C; Morgan, P J; Brydges, R; Kurrek, M; Tregunno, D; Cunningham, L; Chan, A; Forde, D; Tarshis, J


    Although the incidence of major adverse events in surgical daycare centres is low, these critical events may not be managed optimally due to the absence of resources that exist in larger hospitals. We aimed to study the impact of operating theatre critical event checklists on medical management and teamwork during whole-team operating theatre crisis simulations staged in a surgical daycare facility. We studied 56 simulation encounters (without and with a checklist available) divided between an initial session and then a retention session several months later. Medical management and teamwork were quantified via percentage adherence to key processes and the Team Emergency Assessment Measure, respectively. In the initial session, medical management was not improved by the presence of a checklist (56% without checklist vs. 62% with checklist; p = 0.50). In the retention session, teams performed significantly worse without the checklists (36% without checklist vs. 60% with checklist; p = 0.04). We did not observe a change in non-technical skills in the presence of a checklist in either the initial or retention sessions (68% without checklist vs. 69% with checklist (p = 0.94) and 69% without checklist vs. 65% with checklist (p = 0.36), respectively). Critical events checklists do not improve medical management or teamwork during simulated operating theatre crises in an ambulatory surgical daycare setting. © 2016 The Association of Anaesthetists of Great Britain and Ireland.

  15. Tuning hydrological models for ecological modeling - improving simulations of low flows critical to stream ecology

    DEFF Research Database (Denmark)

    Olsen, Martin; Troldborg, Lars; Boegh, Eva


    The consequences of using simulated discharge from a conventional hydrological model as input in stream physical habitat modelling was investigated using output from the Danish national hydrological model and a physical habitat model of three small streams. It was found that low flow simulation e...

  16. Numerical Simulation of Pulsation Flow in the Vapour Channel of Short Low Temperature Heat Pipes at High Heat Loads (United States)

    Seryakov, A. V.; Konkin, A. V.


    The results of the numerical simulation of pulsations in the Laval-liked vapour channel of short low-temperature range heat pipes (HPs) are presented. The numerical results confirmed the experimentally obtained increase of the frequency of pulsations in the vapour channel of short HPs with increasing overheat of the porous evaporator relative to the boiling point of the working fluid. The occurrence of pressure pulsations inside the vapour channel in a short HPs is a complex phenomenon associated with the boiling beginning in the capillary-porous evaporator at high heat loads, and appearance the excess amount of vapour above it, leading to the increase in pressure P to a value at which the boiling point TB of the working fluid becomes higher than the evaporator temperature Tev. Vapour clot spreads through the vapour channel and condense, and then a rarefaction wave return from condenser in the evaporator, the boiling in which is resumed and the next cycle of the pulsations is repeated. Numerical simulation was performed using finite element method implemented in the commercial program ANSYS Multiphisics 14.5 in the two-dimensional setting of axis symmetric moist vapour flow with third kind boundary conditions.

  17. A mathematical model of neuromuscular adaptation to resistance training and its application in a computer simulation of accommodating loads. (United States)

    Arandjelović, Ognjen


    A large corpus of data obtained by means of empirical study of neuromuscular adaptation is currently of limited use to athletes and their coaches. One of the reasons lies in the unclear direct practical utility of many individual trials. This paper introduces a mathematical model of adaptation to resistance training, which derives its elements from physiological fundamentals on the one side, and empirical findings on the other. The key element of the proposed model is what is here termed the athlete's capability profile. This is a generalization of length and velocity dependent force production characteristics of individual muscles, to an exercise with arbitrary biomechanics. The capability profile, a two-dimensional function over the capability plane, plays the central role in the proposed model of the training-adaptation feedback loop. Together with a dynamic model of resistance the capability profile is used in the model's predictive stage when exercise performance is simulated using a numerical approximation of differential equations of motion. Simulation results are used to infer the adaptational stimulus, which manifests itself through a fed back modification of the capability profile. It is shown how empirical evidence of exercise specificity can be formulated mathematically and integrated in this framework. A detailed description of the proposed model is followed by examples of its application-new insights into the effects of accommodating loading for powerlifting are demonstrated. This is followed by a discussion of the limitations of the proposed model and an overview of avenues for future work.

  18. Simulation With Debriefing and Guided Reflective Journaling to Stimulate Critical Thinking in Prelicensure Baccalaureate Degree Nursing Students. (United States)

    Padden-Denmead, Mary L; Scaffidi, Rose M; Kerley, Regina M; Farside, Amy Lee


    Simulation and guided reflective journaling have been identified as effective teaching and learning methods to develop critical thinking (CT) and clinical reasoning skills in nursing students. A descriptive correlational design was used to determine the relationship between CT and level of reflection using the Holistic Critical Thinking Skills Rubric (HCTSR) and the level of reflection on action assessment (LORAA), respectively, to evaluate 23 baccalaureate student-guided reflective journal entries after a simulation exercise with guided debriefing and after two subsequent clinical experiences. A statistically significant positive relationship (p < .01) was found between mean HCTSR and LORAA scores on all three journal entries, but no relationship to CT during simulation or on standardized test scores. The results also indicated support for use of the guided reflection after significant learning experiences. The LORAA and the HCTSR are effective measures of level of reflection and CT to evaluate learning from simulation and clinical experiences. [J Nurs Educ. 2016;55(11):645-650.]. Copyright 2016, SLACK Incorporated.

  19. Simulation of Model Force-Loading with Changing Its Position in the Wind Tunnel Test Section

    Directory of Open Access Journals (Sweden)

    V. T. Bui


    Full Text Available When planning and implementing an aerodynamic experiment, model sizes and its position in the test section of the wind tunnel (WT play very important role. The paper focuses on the value variations of the aerodynamic characteristics of a model through changing its position in the WT test section and on the attenuation of the velocity field disturbance in front of the model. Flow around aerodynamic model profile in the open test section of the low-speed WT T-500 is simulated at BMSTU Department SM3. The problem is solved in a two-dimensional case using the ANSYS Fluent package. The mathematical model of flow is based on the Reynolds equations closed by the SST turbulence model. The paper also presents the results of the experiment. Experiments conducted in WT T-500 well correlate with the calculated data and show the optimal position in the middle of the test section when conducting the weighing and drainage experiments. Disturbance of tunnel dynamic pressure (velocity head and flow upwash around the model profile and circular cylinder in the WT test section is analyzed. It was found that flow upstream from the front stagnation point on the body weakly depends on the Reynolds number and obtained results can be used to assess the level of disturbances in the flow around a model by incompressible airflow.

  20. An Impulse Based Substructuring approach for impact analysis and load case simulations (United States)

    Rixen, Daniel J.; van der Valk, Paul L. C.


    In the present paper we outline the basic theory of assembling substructures for which the dynamics are described as Impulse Response Functions. The assembly procedure computes the time response of a system by evaluating per substructure the convolution product between the Impulse Response Functions and the applied forces, including the interface forces that are computed to satisfy the interface compatibility. We call this approach the Impulse Based Substructuring method since it transposes to the time domain the Frequency Based Substructuring approach. In the Impulse Based Substructuring technique the Impulse Response Functions of the substructures can be gathered either from experimental tests using a hammer impact or from time-integration of numerical submodels. In this paper the implementation of the method is outlined for the case when the impulse responses of the substructures are computed numerically. A simple bar example is shown in order to illustrate the concept. The Impulse Based Substructuring allows fast evaluation of impact response of a structure when the impulse response of its components is known. It can thus be used to efficiently optimize designs of consumer products by including impact behavior at the early stage of the design, but also for performing substructured simulations of complex structures such as offshore wind turbines.

  1. Different effects of fluid loading with saline, gelatine, hydroxyethyl starch or albumin solutions on acid-base status in the critically ill. (United States)

    Spoelstra-de Man, Angélique M E; Smorenberg, Annemieke; Groeneveld, A B Johan


    Fluid administration in critically ill patients may affect acid-base balance. However, the effect of the fluid type used for resuscitation on acid-base balance remains controversial. We studied the effect of fluid resuscitation of normal saline and the colloids gelatine 4%, hydroxyethyl starch (HES) 6%, and albumin 5% on acid-base balance in 115 clinically hypovolemic critically ill patients during a 90 minute filling pressure-guided fluid challenge by a post-hoc analysis of a prospective randomized clinical trial. About 1700 mL was infused per patient in the saline and 1500 mL in each of the colloid groups (Pgelatine- and albumin-loaded patients, independent of lactate concentrations. In clinically hypovolemic, critically ill patients, fluid resuscitation by only 1500-1700 mL of normal saline, gelatine, HES or albumin, resulted in a small decrease in pH, irrespective of the type of fluid used. Therefore, a progressive metabolic acidosis, even with increased anion gap, should not be erroneously attributed to insufficient fluid resuscitation. ISRCTN Registry ISRCTN19023197.

  2. Critical solvent properties affecting the particle formation process and characteristics of celecoxib-loaded plga microparticles via spray-drying. (United States)

    Wan, Feng; Bohr, Adam; Maltesen, Morten Jonas; Bjerregaard, Simon; Foged, Camilla; Rantanen, Jukka; Yang, Mingshi


    It is imperative to understand the particle formation mechanisms when designing advanced nano/microparticulate drug delivery systems. We investigated how the solvent power and volatility influence the texture and surface chemistry of celecoxib-loaded poly (lactic-co-glycolic acid) (PLGA) microparticles prepared by spray-drying. Binary mixtures of acetone and methanol at different molar ratios were applied to dissolve celecoxib and PLGA prior to spray-drying. The resulting microparticles were characterized with respect to morphology, texture, surface chemistry, solid state properties and drug release profile. The evaporation profiles of the feed solutions were investigated using thermogravimetric analysis (TGA). Spherical PLGA microparticles were obtained, irrespectively of the solvent composition. The particle size and surface chemistry were highly dependent on the solvent power of the feed solution. An obvious burst release was observed for the microparticles prepared by the feed solutions with the highest amount of poor solvent for PLGA. TGA analysis revealed distinct drying kinetics for the binary mixtures. The particle formation process is mainly governed by the PLGA precipitation rate, which is solvent-dependent, and the migration rate of celecoxib molecules during drying. The texture and surface chemistry of the spray-dried PLGA microparticles can therefore be tailored by adjusting the solvent composition.

  3. Water Quality, Hydrology, and Simulated Response to Changes in Phosphorus Loading of Butternut Lake, Price and Ashland Counties, Wisconsin, with Special Emphasis on the Effects of Internal Phosphorus Loading in a Polymictic Lake (United States)

    Robertson, Dale M.; Rose, William J.


    63, 23, 9, 3, 1, and 1 percent, respectively. Because of the high internal phosphorus loading, the eutrophication models used in this study were unable to simulate the observed water-quality characteristics in the lake without incorporating this source of phosphorus. However, when internal loading of phosphorus was added to the BATHTUB model, it accurately simulated the average water-quality characteristics measured in MY 2003 and 2004. Model simulations demonstrated a relatively linear response between in-lake total phosphorus concentrations and external phosphorus loading; however, the changes in concentrations were smaller than the changes in external phosphorus loadings (about 25-40 percent of the change in phosphorus loading). Changes in chlorophyll a concentrations, the percentage of days with algal blooms, and Secchi depths were nonlinear and had a greater response to reductions in phosphorus loading than to increases in phosphorus loading. A 50-percent reduction in external phosphorus loading caused an 18-percent decrease in chlorophyll a concentrations, a 41-percent decrease in the percentage of days with algal blooms, and a 12-percent increase in Secchi depth. When the additional internal phosphorus loading was removed from model simulations, all of these constituents showed a much greater response to changes in external phosphorus loading. Because of Butternut Lake's morphometry, it is polymictic, which means it mixes frequently and does not develop stable thermal stratification throughout the summer. This characteristic makes it more vulnerable than dimictic lakes, which mix in spring and fall and develop stable thermal stratification during summer, to the high internal phosphorus loading that has resulted from historically high, nonnatural, external phosphorus loading. In polymictic lakes, the phosphorus released from the sediments is mixed into the upper part of the lake throughout summer. Once Butternut Lake became hypereutrophic (very p

  4. Basic critical care echocardiography: How many studies equate to competence? A pilot study using high fidelity echocardiography simulation. (United States)

    Bowcock, Emma M; Morris, Idunn S; Mclean, Anthony S; Orde, Sam R


    Assessment of competence in basic critical care echocardiography is complex. Competence relies on not only imaging accuracy but also interpretation and appropriate management decisions. The experience to achieve these skills, real-time, is likely more than required for imaging accuracy alone. We aimed to assess the feasibility of using simulation to assess number of studies required to attain competence in basic critical care echocardiography. This is a prospective pilot study recruiting trainees at various degrees of experience in basic critical care echocardiography using experts as reference standard. We used high fidelity simulation to assess speed and accuracy using total time taken, total position difference and total angle difference across the basic acoustic windows. Interpretation and clinical application skills were assessed using a clinical scenario. 'Cut-off' values for number of studies required for competence were estimated. Twenty-seven trainees and eight experts were included. The subcostal view was achieved quickest by trainees (median 23 s, IQR 19-37). Eighty-seven percent of trainees did not achieve accuracy across all views; 81% achieved accuracy with the parasternal long axis and the least accurate was the parasternal short axis (44% of trainees). Fewer studies were required to be considered competent with imaging acquisition compared with competence in correct interpretation and integration (15 vs. 40 vs. 50, respectively). The use of echocardiography simulation to determine competence in basic critical care echocardiography is feasible. Competence in image acquisition appears to be achieved with less experience than correct interpretation and correct management decisions. Further studies are required.

  5. Determination and Distribution of Critical Loads: Application to the Forest Soils in the Autonomous Region of Madrid; Determinacion y Distribucion de Cargas Criticas: Aplicacion a los Suelos forestales de la comunidad Autonoma de Madrid

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, M.; Schmid, T.; Rabago, I. [Ciemat, Madrid (Spain)


    The critical loads of acidity and sulphur have been determined for forest soils within the north and north-west of the Autonomous Region of Madrid. The SMB-CCE and SMB-PROFILE Steady state models have been applied using a 1 km x 1 km resolution. the forest ecosystems have been characterised according to the soil and forest type, slope and climatic data using a Geographic Information System. In order to estimate the critical loads, processes such as weathering rate of the parent material, atmospheric deposition, critical alkalinity leaching rate and nutrients absorbed by the vegetation have been considered. In general the forest soils present high critical load values for acidity and sulphur. The more sensitive zones are found in the north of the Sierra of Guadarrama. Independent of the applied methods, the results are associated to the types of soils where Leptosols have the lowest. Cambisoles and Regosoles intermediate and luvisoles the most elevated values. (Author) 40 refs.

  6. The effect of high-fidelity patient simulation on the critical thinking and clinical decision-making skills of new graduate nurses. (United States)

    Maneval, Rhonda; Fowler, Kimberly A; Kays, John A; Boyd, Tiffany M; Shuey, Jennifer; Harne-Britner, Sarah; Mastrine, Cynthia


    This study was conducted to determine whether the addition of high-fidelity patient simulation to new nurse orientation enhanced critical thinking and clinical decision-making skills. A pretest-posttest design was used to assess critical thinking and clinical decision-making skills in two groups of graduate nurses. Compared with the control group, the high-fidelity patient simulation group did not show significant improvement in mean critical thinking or clinical decision-making scores. When mean scores were analyzed, both groups showed an increase in critical thinking scores from pretest to posttest, with the high-fidelity patient simulation group showing greater gains in overall scores. However, neither group showed a statistically significant increase in mean test scores. The effect of high-fidelity patient simulation on critical thinking and clinical decision-making skills remains unclear. Copyright 2012, SLACK Incorporated.

  7. Simulation of Water Environmental Capacity and Pollution Load Reduction Using QUAL2K for Water Environmental Management (United States)

    Zhang, Ruibin; Qian, Xin; Yuan, Xingcheng; Ye, Rui; Xia, Bisheng; Wang, Yulei


    In recent years, water quality degradation associated with rapid socio-economic development in the Taihu Lake Basin, China, has attracted increasing attention from both the public and the Chinese government. The primary sources of pollution in Taihu Lake are its inflow rivers and their tributaries. Effective water environmental management strategies need to be implemented in these rivers to improve the water quality of Taihu Lake, and to ensure sustainable development in the region. The aim of this study was to provide a basis for water environmental management decision-making. In this study, the QUAL2K model for river and stream water quality was applied to predict the water quality and environmental capacity of the Hongqi River, which is a polluted tributary in the Taihu Lake Basin. The model parameters were calibrated by trial and error until the simulated results agreed well with the observed data. The calibrated QUAL2K model was used to calculate the water environmental capacity of the Hongqi River, and the water environmental capacities of CODCr NH3-N, TN, and TP were 17.51 t, 1.52 t, 2.74 t and 0.37 t, respectively. The results showed that the NH3-N, TN, and TP pollution loads of the studied river need to be reduced by 50.96%, 44.11%, and 22.92%, respectively to satisfy the water quality objectives. Thus, additional water pollution control measures are needed to control and reduce the pollution loads in the Hongqi River watershed. The method applied in this study should provide a basis for water environmental management decision-making. PMID:23222206

  8. Simulation of water environmental capacity and pollution load reduction using QUAL2K for water environmental management. (United States)

    Zhang, Ruibin; Qian, Xin; Yuan, Xingcheng; Ye, Rui; Xia, Bisheng; Wang, Yulei


    In recent years, water quality degradation associated with rapid socio-economic development in the Taihu Lake Basin, China, has attracted increasing attention from both the public and the Chinese government. The primary sources of pollution in Taihu Lake are its inflow rivers and their tributaries. Effective water environmental management strategies need to be implemented in these rivers to improve the water quality of Taihu Lake, and to ensure sustainable development in the region. The aim of this study was to provide a basis for water environmental management decision-making. In this study, the QUAL2K model for river and stream water quality was applied to predict the water quality and environmental capacity of the Hongqi River, which is a polluted tributary in the Taihu Lake Basin. The model parameters were calibrated by trial and error until the simulated results agreed well with the observed data. The calibrated QUAL2K model was used to calculate the water environmental capacity of the Hongqi River, and the water environmental capacities of COD(Cr) NH(3)-N, TN, and TP were 17.51 t, 1.52 t, 2.74 t and 0.37 t, respectively. The results showed that the NH(3)-N, TN, and TP pollution loads of the studied river need to be reduced by 50.96%, 44.11%, and 22.92%, respectively to satisfy the water quality objectives. Thus, additional water pollution control measures are needed to control and reduce the pollution loads in the Hongqi River watershed. The method applied in this study should provide a basis for water environmental management decision-making.

  9. Simulation of Water Environmental Capacity and Pollution Load Reduction Using QUAL2K for Water Environmental Management

    Directory of Open Access Journals (Sweden)

    Yulei Wang


    Full Text Available In recent years, water quality degradation associated with rapid socio-economic development in the Taihu Lake Basin, China, has attracted increasing attention from both the public and the Chinese government. The primary sources of pollution in Taihu Lake are its inflow rivers and their tributaries. Effective water environmental management strategies need to be implemented in these rivers to improve the water quality of Taihu Lake, and to ensure sustainable development in the region. The aim of this study was to provide a basis for water environmental management decision-making. In this study, the QUAL2K model for river and stream water quality was applied to predict the water quality and environmental capacity of the Hongqi River, which is a polluted tributary in the Taihu Lake Basin. The model parameters were calibrated by trial and error until the simulated results agreed well with the observed data. The calibrated QUAL2K model was used to calculate the water environmental capacity of the Hongqi River, and the water environmental capacities of CODCr NH3-N, TN, and TP were 17.51 t, 1.52 t, 2.74 t and 0.37 t, respectively. The results showed that the NH3-N, TN, and TP pollution loads of the studied river need to be reduced by 50.96%, 44.11%, and 22.92%, respectively to satisfy the water quality objectives. Thus, additional water pollution control measures are needed to control and reduce the pollution loads in the Hongqi River watershed. The method applied in this study should provide a basis for water environmental management decision-making.

  10. The Critical Role of the Routing Scheme in Simulating Peak River Discharge in Global Hydrological Models (United States)

    Zhao, Fang; Veldkamp, Ted I. E.; Frieler, Katja; Schewe, Jacob; Ostberg, Sebastian; Willner, Sven; Schauberger, Bernhard; Gosling, Simon N.; Schmied, Hannes Muller; Portmann, Felix T.; hide


    Global hydrological models (GHMs) have been applied to assess global flood hazards, but their capacity to capture the timing and amplitude of peak river discharge which is crucial in flood simulations has traditionally not been the focus of examination. Here we evaluate to what degree the choice of river routing scheme affects simulations of peak discharge and may help to provide better agreement with observations. To this end we use runoff and discharge simulations of nine GHMs forced by observational climate data (1971-2010) within the ISIMIP2a (Inter-Sectoral Impact Model Intercomparison Project phase 2a) project. The runoff simulations were used as input for the global river routing model CaMa-Flood (Catchment-based Macro-scale Floodplain). The simulated daily discharge was compared to the discharge generated by each GHM using its native river routing scheme. For each GHM both versions of simulated discharge were compared to monthly and daily discharge observations from 1701 GRDC (Global Runoff Data Centre) stations as a benchmark. CaMa-Flood routing shows a general reduction of peak river discharge and a delay of about two to three weeks in its occurrence, likely induced by the buffering capacity of floodplain reservoirs. For a majority of river basins, discharge produced by CaMa-Flood resulted in a better agreement with observations. In particular, maximum daily discharge was adjusted, with a multi-model averaged reduction in bias over about two-thirds of the analysed basin area. The increase in agreement was obtained in both managed and near-natural basins. Overall, this study demonstrates the importance of routing scheme choice in peak discharge simulation, where CaMa-Flood routing accounts for floodplain storage and backwater effects that are not represented in most GHMs. Our study provides important hints that an explicit parameterisation of these processes may be essential in future impact studies.

  11. How does variability in input load relate to the probability of critically delayed delivery in a simple Multipart Re-entrant Flow-line problem?

    DEFF Research Database (Denmark)

    Nielsen, Erland Hejn


    this embedded in a multi-part production set-up. Standard simulation methodology relies heavily on the Central Limit Theorem, but as powerful this statistical concept might be it has its pitfalls that as will be shown in this work it can be quite deceptive and consequently harmful. We will focus our discussion...... of the estimation of the probability of critically delayed delivery beyond a specified threshold value given a certain production batch size and try to establish a relation to certain parameters that can be linked to the degree of regularity of the arrival stream of parts to the job/flow-shop. This last aspect...

  12. Effects of Using Human Patient Simulator (HPS versus a CD-ROM on Cognition and Critical Thinking

    Directory of Open Access Journals (Sweden)

    Don Johnson, PhD


    Full Text Available Background: Very little prospective randomized experimental research exists on the use of simulation as a teaching method, and no studies have compared the two strategies of using the HPS and a CD-ROM. In addition, no researchers have investigated the effects of simulation on various levels of cognition, specifically lower-level and higher-level cognition or critical thinking.Objectives: A prospective pretest-posttest experimental mixed design (within and between was used to determine if there were statistically significant differences in HPS and CD-ROM educational strategies in lower-level, higher-level cognition and critical thinking.Results: A repeated measures multivariate analysis of variance (RMANOVA with LSD post-hoc tests were used to analyze the data. There were no significant differences between the HPS and CD-ROM groups on lower-level cognition scores. The HPS group did significantly better than the CD-ROM group on higher-level cognition and critical thinking scores.Conclusion: This study demonstrated that the choice of teaching strategies for lower-level cognition does not make a statistically significant difference in outcome. However, the HPS is superior to using CD-ROM and should be considered as the choice in teaching.

  13. Simulator-based crew resource management training for interhospital transfer of critically ill patients by a mobile ICU. (United States)

    Droogh, Joep M; Kruger, Hanneke L; Ligtenberg, Jack J M; Zijlstra, Jan G


    Transporting critically ill ICU patients by standard ambulances, with or without an accompanying physician, imposes safety risks. In 2007 the Dutch Ministry of Public Health required that all critically ill patients transferred between ICUs in different hospitals be transported by a mobile ICU (MICU). Since March 2009 a specially designed MICU and a retrieval team have served the region near University Medical Center Groningen, in the northeastern region of the Netherlands. The MICU transport program includes simulator-based crew resource management (CRM) training for the intensivists and ICU nurses, who, with the drivers, constitute the MICU crews. Training entails five pivotal aspects: (1) preparation, (2) teamwork, (3) new equipment, (4) mobility, and (5) safety. For example, the training accustoms participants to working in the narrow, moving ambulance and without benefit of additional manpower. The scenario-based team training, which takes about four hours, occurs in a training facility, with its reconstructed ICU, and then in the MICU itself. A "wireless" patient simulator that is able to mimic hemodynamic and respiratory patterns and to simulate lung and heart sounds is used. All scenarios can be adjusted to simulate medical, logistic, or technical problems. Since the start of MICU training in 2009, more than 70 training sessions, involving 100 team members, have been conducted. Quality issues identified include failure to anticipate possible problems (such as failing to ask for intubation of a respiratory-compromised patient at intake); late responses to alarms of the ventilator, perfusor pump, or monitor; and not anticipating a possible shortage of medication. Setting up and implementing simulator-based CRM training provides feasible and helpful preparation for an MICU team.

  14. A critical examination of the maximum velocity of shortening used in simulation models of human movement. (United States)

    Domire, Zachary J; Challis, John H


    The maximum velocity of shortening of a muscle is an important parameter in musculoskeletal models. The most commonly used values are derived from animal studies; however, these values are well above the values that have been reported for human muscle. The purpose of this study was to examine the sensitivity of simulations of maximum vertical jumping performance to the parameters describing the force-velocity properties of muscle. Simulations performed with parameters derived from animal studies were similar to measured jump heights from previous experimental studies. While simulations performed with parameters derived from human muscle were much lower than previously measured jump heights. If current measurements of maximum shortening velocity in human muscle are correct, a compensating error must exist. Of the possible compensating errors that could produce this discrepancy, it was concluded that reduced muscle fibre excursion is the most likely candidate.

  15. The critical role of the routing scheme in simulating peak river discharge in global hydrological models (United States)

    Zhao, Fang; Veldkamp, Ted I. E.; Frieler, Katja; Schewe, Jacob; Ostberg, Sebastian; Willner, Sven; Schauberger, Bernhard; Gosling, Simon N.; Müller Schmied, Hannes; Portmann, Felix T.; Leng, Gobias; Huang, Maoyi; Liu, Xingcai; Tang, Qiuhong; Hanasaki, Naota; Biemans, Hester; Gerten, Dieter; Satoh, Yusuke; Pokhrel, Yadu; Stacke, Tobias; Ciais, Philippe; Chang, Jinfeng; Ducharne, Agnes; Guimberteau, Matthieu; Wada, Yoshihide; Kim, Hyungjun; Yamazaki, Dai


    Global hydrological models (GHMs) have been applied to assess global flood hazards, but their capacity to capture the timing and amplitude of peak river discharge—which is crucial in flood simulations—has traditionally not been the focus of examination. Here we evaluate to what degree the choice of river routing scheme affects simulations of peak discharge and may help to provide better agreement with observations. To this end we use runoff and discharge simulations of nine GHMs forced by observational climate data (1971-2010) within the ISIMIP2a project. The runoff simulations were used as input for the global river routing model CaMa-Flood. The simulated daily discharge was compared to the discharge generated by each GHM using its native river routing scheme. For each GHM both versions of simulated discharge were compared to monthly and daily discharge observations from 1701 GRDC stations as a benchmark. CaMa-Flood routing shows a general reduction of peak river discharge and a delay of about two to three weeks in its occurrence, likely induced by the buffering capacity of floodplain reservoirs. For a majority of river basins, discharge produced by CaMa-Flood resulted in a better agreement with observations. In particular, maximum daily discharge was adjusted, with a multi-model averaged reduction in bias over about 2/3 of the analysed basin area. The increase in agreement was obtained in both managed and near-natural basins. Overall, this study demonstrates the importance of routing scheme choice in peak discharge simulation, where CaMa-Flood routing accounts for floodplain storage and backwater effects that are not represented in most GHMs. Our study provides important hints that an explicit parameterisation of these processes may be essential in future impact studies.


    Directory of Open Access Journals (Sweden)

    A. Akhatova


    Full Text Available The aim of this paper is to consider one of the most traffic-loaded regions of Astana city(Kazakhstan and to determine the concentration of carbon-monoxide (CO in the airduring the peak hours. CFD analysis based on the SolidWorks-EFD platform was used tosimulate the dispersion of contaminants given the estimated emission rates and weatherconditions at the crossroad of Bogenbay Batyr and Zhenis Avenues in Astana.Turbulence prediction was based on k-ε model with wall functions. The governingequations were discretized using the finite volume method and a 2nd order spatialscheme. The mesh verification was based on 1% convergence criterion for a 50% ofmesh density increment; air pressure near the wall of a selected building was chosen asthe parameter to control the convergence. Numerical results are presented for prevailingconditions during all 4 seasons of the year, demonstrating that the highest levels of COare recorded in summer and reach the values up to 11.2 ppm which are still lower thanthe maximum level admitted for humans. Nevertheless, obtained results show thatAstana is gradually becoming a city that is likely to reach the critical levels of pollutantsin the nearest future if control measures are not taken with enough anticipation. As for afuture work, it is proposed to perform in-situ validation of specific scenarios to checkand support the results obtained with CFD and to develop then specific policies fortackling the problem before it becomes evident.

  17. Simulating an Impact of Road Network Improvements on the Performance of Transportation Systems under Critical Load: Agent-based Approach

    NARCIS (Netherlands)

    Milevich, D.; Melnikov, V.; Karbovskii, V.; Krzhizhanovskaya, V.


    In this paper, we analyze the impact of planned road network development on the dynamics of the automobile transportation system during the departure of visitors after the semifinal match of the 2018 FIFA World Cup, which will take place in the newly built stadium on Krestovsky Island. To perform

  18. The simulated effects of wastewater-management actions on the hydrologic system and nitrogen-loading rates to wells and ecological receptors, Popponesset Bay Watershed, Cape Cod, Massachusetts (United States)

    Walter, Donald A.


    The discharge of excess nitrogen into Popponesset Bay, an estuarine system on western Cape Cod, has resulted in eutrophication and the loss of eel grass habitat within the estuaries. Septic-system return flow in residential areas within the watershed is the primary source of nitrogen. Total Maximum Daily Loads (TMDLs) for nitrogen have been assigned to the six estuaries that compose the system, and local communities are in the process of implementing the TMDLs by the partial sewering, treatment, and disposal of treated wastewater at wastewater-treatment facilities (WTFs). Loads of waste-derived nitrogen from both current (1997–2001) and future sources can be estimated implicitly from parcel-scale water-use data and recharge areas delineated by a groundwater-flow model. These loads are referred to as “instantaneous” loads because it is assumed that the nitrogen from surface sources is delivered to receptors instantaneously and that there is no traveltime through the aquifer. The use of a solute-transport model to explicitly simulate the transport of mass through the aquifer from sources to receptors can improve implementation of TMDLs by (1) accounting for traveltime through the aquifer, (2) avoiding limitations associated with the estimation of loads from static recharge areas, (3) accounting more accurately for the effect of surface waters on nitrogen loads, and (4) determining the response of waste-derived nitrogen loads to potential wastewater-management actions. The load of nitrogen to Popponesset Bay on western Cape Cod, which was estimated by using current sources as input to a solute-transport model based on a steady-state flow model, is about 50 percent of the instantaneous load after about 7 years of transport (loads to estuary are equal to loads discharged from sources); this estimate is consistent with simulated advective traveltimes in the aquifer, which have a median of 5 years. Model-calculated loads originating from recharge areas reach 80

  19. Development of Viscoelastic Multi-Body Simulation and Impact Response Analysis of a Ballasted Railway Track under Cyclic Loading

    Directory of Open Access Journals (Sweden)

    Daisuke Nishiura


    Full Text Available Simulation of a large number of deformable bodies is often difficult because complex high-level modeling is required to address both multi-body contact and viscoelastic deformation. This necessitates the combined use of a discrete element method (DEM and a finite element method (FEM. In this study, a quadruple discrete element method (QDEM was developed for dynamic analysis of viscoelastic materials using a simpler algorithm compared to the standard FEM. QDEM easily incorporates the contact algorithm used in DEM. As the first step toward multi-body simulation, the fundamental performance of QDEM was investigated for viscoelastic analysis. The amplitude and frequency of cantilever elastic vibration were nearly equal to those obtained by the standard FEM. A comparison of creep recovery tests with an analytical solution showed good agreement between them. In addition, good correlation between the attenuation degree and the real physical viscosity was confirmed for viscoelastic vibration analysis. Therefore, the high accuracy of QDEM in the fundamental analysis of infinitesimal viscoelastic deformations was verified. Finally, the impact response of a ballast and sleeper under cyclic loading on a railway track was analyzed using QDEM as an application of deformable multi-body dynamics. The results showed that the vibration of the ballasted track was qualitatively in good agreement with the actual measurements. Moreover, the ballast layer with high friction reduced the ballasted track deterioration. This study suggests that QDEM, as an alternative to DEM and FEM, can provide deeper insights into the contact dynamics of a large number of deformable bodies.

  20. Checklist usage decreases critical task omissions when training residents to separate from simulated cardiopulmonary bypass. (United States)

    Petrik, Edward W; Ho, Dennis; Elahi, Maqsood; Ball, Timothy R; Hofkamp, Michael P; Wehbe-Janek, Hania; Culp, William C; Villamaria, Frank J


    Separation from cardiopulmonary bypass (CPB) requires multiple preparatory steps, during which mistakes, omissions, and human errors may occur. Checklists have been used extensively in aviation to improve performance of complex, multistep tasks. The aim of this study was to (1) develop a checklist using a modified Delphi process to identify essential steps necessary to prepare for separation from CPB, and (2) compare the frequency of completed items with and without the use of a checklist in simulation. It was hypothesized that the use of a checklist would reduce the number of omissions. High-fidelity simulation study. University-affiliated tertiary care facility. Seven cardiac anesthesiologists created a checklist using a modified Delphi process. Ten residents participated in 4 scenarios separating from CPB in simulation. Each scenario was performed first without a checklist and then again with a checklist. An observer graded participants' performance. A pre-separation checklist containing 9 tasks was created using the Delphi process. Without using this checklist, 4 tasks were completed in at least 75% of scenarios, and 8 tasks were completed at least 75% of the time when using the checklist. There was a significant improvement in completion of 5 of the 9 items (pchecklist of steps in preparing to separate from CPB. Using this checklist during simulation resulted in increased frequency of completing designated tasks in comparison to relying on memory alone. Checklists may reduce omission errors during complex periods of anesthesiologists' perioperative workflow. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Evaluation of the criticality of cracks in ice shelves using finite element simulations

    Directory of Open Access Journals (Sweden)

    C. Plate


    Full Text Available The ongoing disintegration of large ice shelf parts in Antarctica raise the need for a better understanding of the physical processes that trigger critical crack growth in ice shelves. Finite elements in combination with configurational forces facilitate the analysis of single surface fractures in ice under various boundary conditions and material parameters. The principles of linear elastic fracture mechanics are applied to show the strong influence of different depth dependent functions for the density and the Young's modulus on the stress intensity factor KI at the crack tip. Ice, for this purpose, is treated as an elastically compressible solid and the consequences of this choice in comparison to the predominant incompressible approaches are discussed. The computed stress intensity factors KI for dry and water filled cracks are compared to critical values KIc from measurements that can be found in literature.

  2. Overcoming the Critical Shortage of STEM - Prepared Secondary Students Through Modeling and Simulation (United States)

    Spencer, Thomas; Berry, Brandon


    In developing understanding of technological systems - modeling and simulation tools aid significantly in the learning and visualization processes. In design courses we sketch , extrude, shape, refine and animate with virtual tools in 3D. Final designs are built using a 3D printer. Aspiring architects create spaces with realistic materials and lighting schemes rendered on model surfaces to create breathtaking walk-throughs of virtual spaces. Digital Electronics students design systems that address real-world needs. Designs are simulated in virtual circuits to provide proof of concept before physical construction. This vastly increases students' ability to design and build complex systems. We find students using modeling and simulation in the learning process, assimilate information at a much faster pace and engage more deeply in learning. As Pre-Engineering educators within the Career and Technical Education program at our school division's Technology Academy our task is to help learners in their quest to develop deep understanding of complex technological systems in a variety of engineering disciplines. Today's young learners have vast opportunities to learn with tools that many of us only dreamed about a decade or so ago when we were engaged in engineering and other technical studies. Today's learner paints with a virtual brush - scenes that can aid significantly in the learning and visualization processes. Modeling and simulation systems have become the new standard tool set in the technical classroom [1-5]. Modeling and simulation systems are now applied as feedback loops in the learning environment. Much of the study of behavior change through the use of feedback loops can be attributed to Stanford Psychologist Alfred Bandura. "Drawing on several education experiments involving children, Bandura observed that giving individuals a clear goal and a means to evaluate their progress toward that goal greatly increased the likelihood that they would achieve it."

  3. Considering Face, Rights, and Goals: A Critical Review of Rapport Management in Facilitator-Guided Simulation Debriefing Approaches. (United States)

    Loo, May Eng; Krishnasamy, Charmaine; Lim, Wee Shiong


    The rapport between facilitators and learners contributes to a conducive learning environment during simulation debriefing, but a theory to guide rapport management (RM) is lacking. The RM model is a potentially relevant conceptual framework because it describes three interrelated components of rapport-face, rights, and goals-which, when threatened, affect the rapport between interactants. This critical review explores how studies in the simulation debriefing literature describing postevent facilitator-guided debriefing approaches can be viewed through the lens of the RM model. All 34 identified studies alluded to at least one component of rapport, with less than half alluding to all three. There is preliminary evidence that the management of all three components of rapport during debriefing may contribute to improving short-term learning outcomes. Future studies could explore how the RM model can be used to guide debriefing approaches in various contexts and clarify why or how these approaches work.

  4. A piloted simulator investigation of stability and control, display and crew-loading requirements for helicopter instrument approach. Part 1: Technical discussion and results (United States)

    Lebacqz, J. V.; Forrest, R. D.; Gerdes, R. M.


    A ground-simulation experiment was conducted to investigate the influence and interaction of flight-control system, fight-director display, and crew-loading situation on helicopter flying qualities during terminal area operations in instrument conditions. The experiment was conducted on the Flight Simulator for Advanced Aircraft at Ames Research Center. Six levels of control complexity, ranging from angular rate damping to velocity augmented longitudinal and vertical axes, were implemented on a representative helicopter model. The six levels of augmentation were examined with display variations consisting of raw elevation and azimuth data only, and of raw data plus one-, two-, and three-cue flight directors. Crew-loading situations simulated for the control-display combinations were dual-pilot operation (representative auxiliary tasks of navigation, communications, and decision-making). Four pilots performed a total of 150 evaluations of combinations of these parameters for a representative microwave landing system (MLS) approach task.

  5. What Controls Thermo-osmosis? Molecular Simulations Show the Critical Role of Interfacial Hydrodynamics (United States)

    Fu, Li; Merabia, Samy; Joly, Laurent


    Thermo-osmotic and related thermophoretic phenomena can be found in many situations from biology to colloid science, but the underlying molecular mechanisms remain largely unexplored. Using molecular dynamics simulations, we measure the thermo-osmosis coefficient by both mechanocaloric and thermo-osmotic routes, for different solid-liquid interfacial energies. The simulations reveal, in particular, the crucial role of nanoscale interfacial hydrodynamics. For nonwetting surfaces, thermo-osmotic transport is largely amplified by hydrodynamic slip at the interface. For wetting surfaces, the position of the hydrodynamic shear plane plays a key role in determining the amplitude and sign of the thermo-osmosis coefficient. Finally, we measure a giant thermo-osmotic response of the water-graphene interface, which we relate to the very low interfacial friction displayed by this system. These results open new perspectives for the design of efficient functional interfaces for, e.g., waste-heat harvesting.

  6. Large Eddy simulation of turbulent flow past a circular cylinder in the subcritical and critical regimes

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyongjun; Yang, Kyung-Soo [Inha University, Incheon (Korea, Republic of)


    Large Eddy simulation (LES) results of turbulent flow past a circular cylinder for the specified Reynolds numbers (Re = 63100, 126000, 252000) are presented. An immersed boundary method was employed to facilitate implementation of a circular cylinder in a Cartesian grid system. A dynamic subgrid-scale model, in which the model coefficient is dynamically determined by the current resolved flow field rather than assigned a prefixed constant, was implemented for accurate turbulence modeling. For better resolution near the cylinder surface and in the separated free-shear layers, a composite grid was used. Flow statistics including mean and rms values of force coefficients and Strouhal number of vortex shedding, are presented. Flow visualization using vorticity or Q contours are also shown. Our results are in better agreement with the MARIN measurements compared with RANS calculations reported in the previous ITTC workshop, confirming that LES is a more appropriate simulation methodology than a RANS approach to predict VIV for marine structures.

  7. Modeling and Simulation in the Army Intermediate Level Education Critical Thinking Curriculum (United States)


    in its history . As the battlefield continues to evolve, as enemies continue to blend into the population and continue to affect the world as actors...thinking lessons in the classroom environment. This area is approached in two ways. First, it was assumed that at some point in history , simulations...CHAPTER 4 ANALYSIS It is the mark of an educated mind to be able to entertain a thought without accepting it. — Aristotle Section I

  8. Development of a new simulation code for evaluation of criticality transients involving fissile solution boiling

    Energy Technology Data Exchange (ETDEWEB)

    Basoglu, Benan; Yamamoto, Toshihiro; Okuno, Hiroshi; Nomura, Yasushi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment


    In this work, we report on the development of a new computer code named TRACE for predicting the excursion characteristics of criticality excursions involving fissile solutions. TRACE employs point neutronics coupled with simple thermal-hydraulics. The temperature, the radiolytic gas effects, and the boiling phenomena are estimated using the transient heat conduction equation, a lumped-parameter energy model, and a simple boiling model, respectively. To evaluate the model, we compared our results with the results of CRAC experiments. The agreement in these comparisons is quite satisfactory. (author)

  9. Impact of air-abrasion on fracture load and failure type of veneered anterior Y-TZP crowns before and after chewing simulation. (United States)

    Stawarczyk, Bogna; Ozcan, Mutlu; Hallmann, Lubica; Roos, Malgorzata; Trottmann, Albert; Hämmerle, Christoph H F


    The purpose of this study was to determine the fracture load and failure types of veneered zirconia crowns that were air-abraded on either the veneering or cementation surface. Fracture loads were determined before and after chewing simulation. Standardized Y-TZP frameworks (n = 360) for canines were fabricated and divided into one control group (n = 72) and 12 test groups (n = 24). The test groups were air-abraded using alumina powder (10 s, 2 bar, distance: 10 mm) with particle size of 50 μm resp. 110 μm and veneered with one of the veneering ceramics: Triceram, Zirox, or VITA VM9. The crowns were cemented on their corresponding CoCr abutment. The initial fracture load was measured in one half of each group (n = 12), and the other half (n = 12) was subjected to chewing cycling. The data were analyzed using three-way and one-way ANOVA, a post-hoc Scheffé test, two sample Student's t-test, and Weibull statistics (p veneering ceramics (Triceram, VITA VM9) showed higher mean fracture load compared to control groups. After chewing simulation, air-abraded groups showed lower mean fracture load compared to control groups. Aging decreased the Weibull modulus of all tested groups, and air-abraded groups showed lower Weibull moduli compared to control groups. Copyright © 2012 Wiley Periodicals, Inc.

  10. Integrated modeling approach using SELECT and SWAT models to simulate source loading and in-stream conditions of fecal indicator bacteria. (United States)

    Ranatunga, T.


    Modeling of fate and transport of fecal bacteria in a watershed is generally a processed based approach that considers releases from manure, point sources, and septic systems. Overland transport with water and sediments, infiltration into soils, transport in the vadose zone and groundwater, die-off and growth processes, and in-stream transport are considered as the other major processes in bacteria simulation. This presentation will discuss a simulation of fecal indicator bacteria (E.coli) source loading and in-stream conditions of a non-tidal watershed (Cedar Bayou Watershed) in South Central Texas using two models; Spatially Explicit Load Enrichment Calculation Tool (SELECT) and Soil and Water Assessment Tool (SWAT). Furthermore, it will discuss a probable approach of bacteria source load reduction in order to meet the water quality standards in the streams. The selected watershed is listed as having levels of fecal indicator bacteria that posed a risk for contact recreation and wading by the Texas Commission of Environmental Quality (TCEQ). The SELECT modeling approach was used in estimating the bacteria source loading from land categories. Major bacteria sources considered were, failing septic systems, discharges from wastewater treatment facilities, excreta from livestock (Cattle, Horses, Sheep and Goat), excreta from Wildlife (Feral Hogs, and Deer), Pet waste (mainly from Dogs), and runoff from urban surfaces. The estimated source loads were input to the SWAT model in order to simulate the transport through the land and in-stream conditions. The calibrated SWAT model was then used to estimate the indicator bacteria in-stream concentrations for future years based on H-GAC's regional land use, population and household projections (up to 2040). Based on the in-stream reductions required to meet the water quality standards, the corresponding required source load reductions were estimated.

  11. Biological Insights from a Simulation Model of the Critical FtsZ Accumulation Required for Prokaryotic Cell Division. (United States)

    Dow, Claire E; van den Berg, Hugo A; Roper, David I; Rodger, Alison


    A simulation model of prokaryotic Z-ring assembly, based on the observed behavior of FtsZ in vitro as well as on in vivo parameters, is used to integrate critical processes in cell division. According to the model, the cell's ability to divide depends on a "contraction parameter" (χ) that links the force of contraction to the dynamics of FtsZ. This parameter accurately predicts the outcome of division. Evaluating the GTP binding strength, the FtsZ polymerization rate, and the intrinsic GTP hydrolysis/dissociation activity, we find that inhibition of GTP-FtsZ binding is an inefficient antibacterial target. Furthermore, simulations indicate that the temperature sensitivity of the ftsZ84 mutation arises from the conversion of FtsZ to a dual-specificity NTPase. Finally, the sensitivity to temperature of the rate of ATP hydrolysis, over the critical temperature range, leads us to conclude that the ftsZ84 mutation affects the turnover rate of the Z-ring much less strongly than previously reported.

  12. The critical speed of the Deutsche Reichsbahn's class-05 steam locomotive; Berechnung der kritischen Geschwindigkeit mittels Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Eckstein, Johannes [Stuttgart Univ. (Germany). Inst. fuer Technische und Numerische Mechanik; Heer, Andreas [Bosch Engineering GmbH, Abstatt (Germany). Bremsregelsysteme; Meinke, Peter [IAT Ingenieurgesellschaft fuer Angewandte Technologie mbH, Gauting (Germany); Wiese, Christoph [Stuttgart Univ. (Germany). Inst. fuer Leistungselektronik und Elektrische Antriebe, Stuttgart


    Modern high-speed trains are equipped with running gear that has been optimised for lateral stability at normal operational speeds and the minimisation of phenomena such as hunting oscillations. What, however, was the situation when the new world railway speed record of 200.4 km/h was established on 11 May 1936 by a steam locomotive, 05 002, hauling a rake of four passenger coaches? In those days, nobody was in a position to calculate critical speeds. It has only been since we have had access to computers that it has been possible to establish critical speeds mathematically by running simulations (using programs like SIMPACK). The simulation's output has shown that, provided the tender was rigidly coupled to the locomotive, these two vehicles together would have had stable running properties up to approximately 245 km/h. Evidence has at last been produced to show that the record-breaking run of 200.5 km/h was not in any danger on account of excessive instability due to hunting oscillations. (orig.)

  13. The effects of using a human patient simulator compared to a CD-ROM in teaching critical thinking and performance. (United States)

    Johnson, Don; Johnson, Sabine


    Military healthcare personnel, including nurse anesthetists, must have the knowledge and skills to care for the extensive, severe injuries incurred on the battlefield. No studies have compared the 2 teaching strategies of using the human patient simulator (HPS) and a CD-ROM in caring for combat injuries relative to critical thinking and performance using nurse anesthesia participants. A prospective, pretest-posttest experimental, mixed design (within and between) was used to determine if there were statistically significant differences in HPS and CD-ROM educational strategies relative to caring for patients who have trauma. Two instruments were used: critical thinking, which consisted of multiple-choice questions; and a combat performance instrument that measured ability to care for patients. A repeated analysis of variance and a least significant difference post-hoc test were used to analyze the data. The HPS group performed better than the CD-ROM and control groups relative to performance (P=.000) but not on critical thinking (P=.239). There was no difference between the CD-ROM and control group (P=.171) on the combat performance instrument. In this study, the HPS method of instruction was a more effective method of teaching than the CD-ROM approach.

  14. Antibody humanization by molecular dynamics simulations-in-silico guided selection of critical backmutations. (United States)

    Margreitter, Christian; Mayrhofer, Patrick; Kunert, Renate; Oostenbrink, Chris


    Monoclonal antibodies represent the fastest growing class of biotherapeutic proteins. However, as they are often initially derived from rodent organisms, there is a severe risk of immunogenic reactions, hampering their applicability. The humanization of these antibodies remains a challenging task in the context of rational drug design. "Superhumanization" describes the direct transfer of the complementarity determining regions to a human germline framework, but this humanization approach often results in loss of binding affinity. In this study, we present a new approach for predicting promising backmutation sites using molecular dynamics simulations of the model antibody Ab2/3H6. The simulation method was developed in close conjunction with novel specificity experiments. Binding properties of mAb variants were evaluated directly from crude supernatants and confirmed using established binding affinity assays for purified antibodies. Our approach provides access to the dynamical features of the actual binding sites of an antibody, based solely on the antibody sequence. Thus we do not need structural data on the antibody-antigen complex and circumvent cumbersome methods to assess binding affinities. © 2016 The Authors Journal of Molecular Recognition Published by John Wiley & Sons Ltd. © 2016 The Authors Journal of Molecular Recognition Published by John Wiley & Sons Ltd.

  15. The Impact of Critical Thinking on Clinical Judgment During Simulation With Senior Nursing Students. (United States)

    Cazzell, Mary; Anderson, Mindi


    The study examined the impact of critical thinking (CT) on clinical judgment (CJ) during a pediatric Objective Structured Clinical Evaluation (OSCE) with 160 pre-licensure nursing students. Educators are called to transform teaching strategies to develop CJ but confusion exists over definitions. A descriptive correlational design was used to examine demographics and Tower of Hanoi (TOH) and Health Science Reasoning Test (HSRT) scores. CJ was measured by scores on the Lasater Clinical Judgment Rubric (LCJR) from videotaped OSCEs. Participants were: 86 percent female, 42 percent Caucasian, median 23 years, with 49 percent having health care experience. Students averaged seven moves over minimum on the TOH. Average scores were: HSRT 25/38 and LCJR 31/44. Statistically significant predictors of CJ were gender, ethnicity, HSRT deduction, and analysis; 11 CT variables accounted for 17 percent of LCJR scores. Educators need to utilize/develop innovative teaching strategies addressing CJ predictors.

  16. Toward an ontology framework supporting the integration of geographic information with modeling and simulation for critical infrastructure protection

    Energy Technology Data Exchange (ETDEWEB)

    Ambrosiano, John J [Los Alamos National Laboratory; Bent, Russell W [Los Alamos National Laboratory; Linger, Steve P [Los Alamos National Laboratory


    Protecting the nation's infrastructure from natural disasters, inadvertent failures, or intentional attacks is a major national security concern. Gauging the fragility of infrastructure assets, and understanding how interdependencies across critical infrastructures affect their behavior, is essential to predicting and mitigating cascading failures, as well as to planning for response and recovery. Modeling and simulation (M&S) is an indispensable part of characterizing this complex system of systems and anticipating its response to disruptions. Bringing together the necessary components to perform such analyses produces a wide-ranging and coarse-grained computational workflow that must be integrated with other analysis workflow elements. There are many points in both types of work flows in which geographic information (GI) services are required. The GIS community recognizes the essential contribution of GI in this problem domain as evidenced by past OGC initiatives. Typically such initiatives focus on the broader aspects of GI analysis workflows, leaving concepts crucial to integrating simulations within analysis workflows to that community. Our experience with large-scale modeling of interdependent critical infrastructures, and our recent participation in a DRS initiative concerning interoperability for this M&S domain, has led to high-level ontological concepts that we have begun to assemble into an architecture that spans both computational and 'world' views of the problem, and further recognizes the special requirements of simulations that go beyond common workflow ontologies. In this paper we present these ideas, and offer a high-level ontological framework that includes key geospatial concepts as special cases of a broader view.

  17. Three-Dimensional Electromagnetic Monte Carlo Particle-in-Cell Simulations of Critical Ionization Velocity Experiments in Space (United States)

    Wang, J.; Biasca, R.; Liewer, P. C.


    Although the existence of the critical ionization velocity (CIV) is known from laboratory experiments, no agreement has been reached as to whether CIV exists in the natural space environment. In this paper we move towards more realistic models of CIV and present the first fully three-dimensional, electromagnetic particle-in-cell Monte-Carlo collision (PIC-MCC) simulations of typical space-based CIV experiments. In our model, the released neutral gas is taken to be a spherical cloud traveling across a magnetized ambient plasma. Simulations are performed for neutral clouds with various sizes and densities. The effects of the cloud parameters on ionization yield, wave energy growth, electron heating, momentum coupling, and the three-dimensional structure of the newly ionized plasma are discussed. The simulations suggest that the quantitative characteristics of momentum transfers among the ion beam, neutral cloud, and plasma waves is the key indicator of whether CIV can occur in space. The missing factors in space-based CIV experiments may be the conditions necessary for a continuous enhancement of the beam ion momentum. For a typical shaped charge release experiment, favorable CIV conditions may exist only in a very narrow, intermediate spatial region some distance from the release point due to the effects of the cloud density and size. When CIV does occur, the newly ionized plasma from the cloud forms a very complex structure due to the combined forces from the geomagnetic field, the motion induced emf, and the polarization. Hence the detection of CIV also critically depends on the sensor location.

  18. Experimental and Simulated Investigations of Thin Polymer Substrates with an Indium Tin Oxide Coating under Fatigue Bending Loadings

    Directory of Open Access Journals (Sweden)

    Jiong-Shiun Hsu


    Full Text Available Stress-induced failure is a critical concern that influences the mechanical reliability of an indium tin oxide (ITO film deposited on a transparently flexible polyethylene terephthalate (PET substrate. In this study, a cycling bending mechanism was proposed and used to experimentally investigate the influences of compressive and tensile stresses on the mechanical stability of an ITO film deposited on PET substrates. The sheet resistance of the ITO film, optical transmittance of the ITO-coated PET substrates, and failure scheme within the ITO film were measured to evaluate the mechanical stability of the concerned thin films. The results indicated that compressive and tensile stresses generated distinct failure schemes within an ITO film and both led to increased sheet resistance and optical transmittance. In addition, tensile stress increased the sheet resistance of an ITO film more easily than compressive stress did. However, the influences of both compressive and tensile stress on increased optical transmittance were demonstrated to be highly similar. Increasing the thickness of a PET substrate resulted in increased sheet resistance and optical transmittance regardless of the presence of compressive or tensile stress. Moreover, J-Integral, a method based on strain energy, was used to estimate the interfacial adhesion strength of the ITO-PET film through the simulation approach enabled by a finite element analysis.

  19. Critical Experiments that Simulated Damp MOX Powders - Do They Meet the Need?

    Energy Technology Data Exchange (ETDEWEB)

    J. Blair Briggs; Dr. Ali Nouri; Dr. Claes Nordborg


    The OECD Nuclear Energy Agency (NEA) Working Party on Nuclear Criticality Safety (WPNCS) identified the MOX fuel manufacturing process as an area in which there is a need for additional integral benchmark data. The specific need focused on damp MOX powders. The WPNCS was ultimately asked by the NEA Nuclear Science Committee (NSC) to provide the framework for the selection and performance of new experiments that fill the identified need. A set of criteria was established to enable uniform comparison of experimental proposals with generic MOX application data. Criteria were established for five general characteristics: (1) neutronic parameters, (2) type of experiments, (3) financial aspects, (4) schedule, and (5) other considerations. Proposals were judged most importantly on their ability to match the neutronic parameters of predetermined MOX applications. The neutronic parameters that formed the basis for comparison included core average values (not local values) for flux, fission and capture rate; detailed balance data (fission and capture) for the main isotopes (Actinides, H and O); sensitivity coefficients to important nuclear reactions (fission, capture, elastic and inelastic scatter, nu-bar, mu-bar) for all uranium and plutonium isotopes, hydrogen, and oxygen; sensitivity profiles to the main nuclear reactions for uranium and plutonium isotopes; energy of average lethargy causing fission; and the average fission group energy. The focus of this paper is on the definition of the need; the neutronics criteria established to assess which, if any, of three proposed MOX experimental programs best meet the need; and the actual assessment of the proposed experimental programs.

  20. Combining simulation, instructor-produced videos, and online discussions to stimulate critical thinking in nursing students. (United States)

    Guhde, Jacqueline


    Combining the use of several different types of technology enables an instructor to develop teaching methods to address a specific problem area that students encounter and can greatly affect student learning. This article discusses a program that was developed that utilized SimMan, instructor-produced videos, and online discussion to stimulate critical thinking in beginning-level nursing students. The goal was to make the student aware of the importance of an initial thorough assessment of a client. This is especially difficult since new students are focused on learning the skills and have not had enough clinical experience to appreciate the importance of assessment. The first two videos show a nurse who makes a very incomplete assessment of the client and misses important observations. This leads to the patient (SimMan) going into respiratory distress. The third video demonstrates a complete assessment. The students viewed and discussed the first two videos online. After the third video, students posted their own reflections of this activity including what they learned and how this would change their behavior. The outcome showed an increased awareness of the importance of assessment. Instructors observed a change in behavior, which included early assessment of the client.