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Sample records for simulated critical loads

  1. Evaluation of cognitive load and emotional states during multidisciplinary critical care simulation sessions.

    Science.gov (United States)

    Pawar, Swapnil; Jacques, Theresa; Deshpande, Kush; Pusapati, Raju; Meguerdichian, Michael J

    2018-04-01

    The simulation in critical care setting involves a heterogeneous group of participants with varied background and experience. Measuring the impacts of simulation on emotional state and cognitive load in this setting is not often performed. The feasibility of such measurement in the critical care setting needs further exploration. Medical and nursing staff with varying levels of experience from a tertiary intensive care unit participated in a standardised clinical simulation scenario. The emotional state of each participant was assessed before and after completion of the scenario using a validated eight-item scale containing bipolar oppositional descriptors of emotion. The cognitive load of each participant was assessed after the completion of the scenario using a validated subjective rating tool. A total of 103 medical and nursing staff participated in the study. The participants felt more relaxed (-0.28±1.15 vs 0.14±1, Pcognitive load for all participants was 6.67±1.41. There was no significant difference in the cognitive loads among medical staff versus nursing staff (6.61±2.3 vs 6.62±1.7; P>0.05). A well-designed complex high fidelity critical care simulation scenario can be evaluated to identify the relative cognitive load of the participants' experience and their emotional state. The movement of learners emotionally from a more negative state to a positive state suggests that simulation can be an effective tool for improved knowledge transfer and offers more opportunity for dynamic thinking.

  2. Simulation of Mechanical Behavior and Damage of a Large Composite Wind Turbine Blade under Critical Loads

    Science.gov (United States)

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

    2018-04-01

    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.

  3. Empirical and simulated critical loads for nitrogen deposition in California mixed conifer forests

    International Nuclear Information System (INIS)

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

    2008-01-01

    Empirical critical loads (CL) for N deposition were determined from changes in epiphytic lichen communities, elevated NO 3 - 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 -1 is expected to protect all components of the forest ecosystem from the adverse effects of N deposition. Much of the western Sierra Nevada is above the lichen-based CL, showing significant changes in lichen indicator groups. The empirical N deposition threshold and that simulated by the DayCent model for enhanced NO 3 - leaching were 17 kg N ha -1 year -1 . DayCent estimated that elevated NO 3 - leaching in the San Bernardino Mountains began in the late 1950s. Critical values for litter C:N (34.1), ponderosa pine foliar N (1.1%), and N concentrations (1.0%) in the lichen Letharia vulpina ((L.) Hue) are indicative of CL exceedance. - Critical loads for N deposition effects on lichens, trees and nitrate leaching provide benchmarks for protecting California forests

  4. Empirical and simulated critical loads for nitrogen deposition in California mixed conifer forests

    Energy Technology Data Exchange (ETDEWEB)

    Fenn, M.E. [USDA Forest Service, Pacific Southwest Research Station, 4955 Canyon Crest Drive, Riverside, CA 92507 (United States)], E-mail: mfenn@fs.fed.us; Jovan, S. [USDA Forest Service, Pacific Northwest Research Station, 620 SW Main, Suite 400, Portland, OR 97205 (United States); Yuan, F. [Department of Hydrology and Water Resources, University of Arizona, Tucson, AZ 85721 (United States); Geiser, L. [USDA Forest Service, Pacific Northwest Air Resource Management Program, PO Box 1148, Corvallis, OR 97339 (United States); Meixner, T. [Department of Hydrology and Water Resources, University of Arizona, Tucson, AZ 85721 (United States); Gimeno, B.S. [Ecotoxicology of Air Pollution, CIEMAT (ed. 70), Avda. Complutense 22, 28040 Madrid (Spain)

    2008-10-15

    Empirical critical loads (CL) for N deposition were determined from changes in epiphytic lichen communities, elevated NO{sub 3}{sup -} 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{sup -1} year{sup -1} is expected to protect all components of the forest ecosystem from the adverse effects of N deposition. Much of the western Sierra Nevada is above the lichen-based CL, showing significant changes in lichen indicator groups. The empirical N deposition threshold and that simulated by the DayCent model for enhanced NO{sub 3}{sup -}leaching were 17 kg N ha{sup -1} year{sup -1}. DayCent estimated that elevated NO{sub 3}{sup -} leaching in the San Bernardino Mountains began in the late 1950s. Critical values for litter C:N (34.1), ponderosa pine foliar N (1.1%), and N concentrations (1.0%) in the lichen Letharia vulpina ((L.) Hue) are indicative of CL exceedance. - Critical loads for N deposition effects on lichens, trees and nitrate leaching provide benchmarks for protecting California forests.

  5. Critical Axial Load

    Directory of Open Access Journals (Sweden)

    Walt Wells

    2008-01-01

    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.

  6. LOADING SIMULATION PROGRAM C

    Science.gov (United States)

    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

  7. LOADING SIMULATION PROGRAM C

    Data.gov (United States)

    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...

  8. Critical loads - assessment of uncertainty

    Energy Technology Data Exchange (ETDEWEB)

    Barkman, A.

    1998-10-01

    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

  9. Nitrogen critical loads using biodiversity-related critical limits

    International Nuclear Information System (INIS)

    Posch, Maximilian; Aherne, Julian; Hettelingh, Jean-Paul

    2011-01-01

    Critical loads are widely used in the effects-based assessment of emission reduction policies. While the impacts of acidification have diminished, there is increasing concern regarding the effects of nitrogen deposition on terrestrial ecosystems. In this context much attention has been focussed on empirical critical loads as well as simulations with linked geochemistry-vegetation models. Surprisingly little attention has been paid to adapt the widely used simple mass balance approach. This approach has the well-established benefit of easy regional applicability, while incorporating specified critical chemical criteria to protect specified receptors. As plant occurrence/biodiversity is related to both the nutrient and acidity status of an ecosystem, a single abiotic factor (chemical criterion) is not sufficient. Rather than an upper limit for deposition (i.e., critical load), linked nutrient nitrogen and acidity chemical criteria for plant occurrence result in an 'optimal' nitrogen and sulphur deposition envelope. - Highlights: → Mass balance critical load approaches for nutrient nitrogen remain useful. → Biodiversity-related limits are related to nutrient and acidity status. → Nutrient and acidity chemical criteria lead to optimal deposition envelopes. → Optimal loads support effects-based emission reduction policies. - Biodiversity-related critical limits lead to optimal nitrogen and sulphur deposition envelopes for plant species or species compositions.

  10. The concept of target and critical loads

    International Nuclear Information System (INIS)

    Grigal, D.F.

    1991-09-01

    Target and critical loads were initially developed for assessment and control of acidic deposition, but are being considered for other air pollutants such as ozone and air-borne toxic compounds. These loads are based on thresholds, with damage assumed to occur above some defined level of deposition. Many of the historically proposed targets for acidic deposition were based on arbitrary interpretations of data. The concept of critical loads has recently separated from that of target loads. A critical load is the amount of pollutant deposition, determined by technical analysis, above which there is a specific deleterious ecological effect. A target load is the deposition, determined by political agreement, above which unacceptable ecological damage occurs; it may be greater than the critical load because of political or economic considerations, or less to conservatively account for uncertainty in the estimation of the critical load. Recent definitions of critical loads include recognition that each kind of ecosystem and effect may require a different load. Geographic regions contain a mosaic of aquatic and terrestrial resources. If precise knowledge leads to different critical loads for each system, then how is the regional target load established? For better or worse, target and critical loads are likely to be used to regulate air pollutants. The philosophy of their establishment as thresholds, their quantitative validity, and their application in regulation all require careful examination. 36 refs., 3 figs

  11. Research of Impact Load in Large Electrohydraulic Load Simulator

    Directory of Open Access Journals (Sweden)

    Yongguang Liu

    2014-01-01

    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.

  12. Results of the critical experiments concerning OTTO loading at the critical HTR-test facility KAHTER

    International Nuclear Information System (INIS)

    Drueke, V.; Litzow, W.; Paul, N.

    1982-12-01

    Critical experiments concerning OTTO loading are described. In the KAHTER facility an OTTO loading has been simulated, therefore the original KAHTER assembly was reconstructed. The determination of critical masses and reactivity worths of control rods and of additional absorber rods in the top reflector and in the upper cavity was of main interest for comparison with reactor following calculations. Besides this, reaction rates in different energy regions were measured in the upper part of the core, in the cavity and top reflector. (orig.) [de

  13. Criticality conditions of heterogeneous energetic materials under shock loading

    Science.gov (United States)

    Nassar, Anas; Rai, Nirmal Kumar; Sen, Oishik; Udaykumar, H. S.

    2017-06-01

    Shock interaction with the microstructural heterogeneities of energetic materials can lead to the formation of locally heated regions known as hot spots. These hot spots are the potential sites where chemical reaction may be initiated. However, the ability of a hot spot to initiate chemical reaction depends on its size, shape and strength (temperature). Previous study by Tarver et al. has shown that there exists a critical size and temperature for a given shape (spherical, cylindrical, and planar) of the hot spot above which reaction initiation is imminent. Tarver et al. assumed a constant temperature variation in the hot spot. However, the meso-scale simulations show that the temperature distribution within a hot spot formed from processes such as void collapse is seldom constant. Also, the shape of a hot spot can be arbitrary. This work is an attempt towards development of a critical hot spot curve which is a function of loading strength, duration and void morphology. To achieve the aforementioned goal, mesoscale simulations are conducted on porous HMX material. The process is repeated for different loading conditions and void sizes. The hot spots formed in the process are examined for criticality depending on whether they will ignite or not. The metamodel is used to obtain criticality curves and is compared with the critical hot spot curve of Tarver et al.

  14. Peak load-impulse characterization of critical pulse loads in structural dynamics

    International Nuclear Information System (INIS)

    Abrahamson, G.R.; Lindberg, H.E.

    1975-01-01

    In presenting the characterization scheme, some general features are described first. A detailed analysis is given for the rigid-plastic system of one degree of freedom to illustrate the calculation of critical load curves in terms of peak load and impulse. This is followed by the presentation of critical load curves for uniformly loaded rigid-plastic beams and plates and for dynamic buckling of cylindrical shells under uniform lateral loads. The peak load-impulse characterization of critical pulse loads is compared with the dynamic load factor characterization, and some aspects of the history of the peak load-pulse scheme are presented. (orig./HP) [de

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

    DEFF Research Database (Denmark)

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

    2009-01-01

    . 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.......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...... 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...

  16. Simulation of Stochastic Loads for Fatigue Experiments

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Brincker, Rune

    1989-01-01

    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......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...... 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. Simulation of Stochastic Loads for Fatigue Experiments

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Brincker, Rune

    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 is results in a simulation speed at about 3000 load cycles per......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...... 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...

  18. Modelling and Simulation of Wave Loads

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Thoft-Christensen, Palle

    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......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...

  19. Modelling and Simulation of Wave Loads

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Thoft-Christensen, Palle

    1985-01-01

    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......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...

  20. Methods for monitoring the initial load to critical in the fast test reactor

    International Nuclear Information System (INIS)

    Johnson, D.L.

    1975-08-01

    Conventional symmetric fuel loadings for the initial loading to critical of the Fast Test Reactor (FTR) are predicted to be more time consuming than asymmetric or trisector loadings. Potentially significant time savings can be realized by the latter, since adequate intermediate assessments of neutron multiplication can be made periodically without control rod reconnection in all trisectors. Experimental simulation of both loading schemes was carried out in the Reverse Approach to Critical (RAC) experiments in the Fast Test Reactor-Engineering Mockup Critical facility. Analyses of these experiments indicated that conventional source multiplication methods can be applied for monitoring either a symmetric or asymmetric fuel loading scheme equally well provided that detection efficiency corrections are employed. Methods for refining predictions of reactivity and count rates for the stages in a load to critical were also investigated. (auth)

  1. Critical traffic loading for the design of prestressed concrete bridge

    International Nuclear Information System (INIS)

    Hassan, M.I.U.

    2009-01-01

    A study has been carried out to determine critical traffic loadings for the design of bridge superstructures. The prestressed concrete girder bridge already constructed in Lahore is selected for the analysis as an example. Standard traffic loadings according to AASHTO (American Association of State Highway and Transportation Officials) and Pakistan Highway Standards are used for this purpose. These include (1) HL-93 Truck, (2) Lane and (3) Tandem Loadings in addition to (4) Military tank loading, (5) Class-A, (6) Class-B and (7) Class-AA loading, (8) NLC (National Logistic Cell) and (9) Volvo truck loadings. Bridge superstructure including transom beam is analyzed Using ASD and LRFD (Load and Resistance Factor Design) provisions of AASHTO specifications. For the analysis, two longer and shorter spans are selected. This includes the analysis of bridge deck; interior and exterior girder; a typical transom beam and a pier. Dead and live loading determination is carried out using both computer aided and manual calculations. Evaluation of traffic loadings is done for all the bridge components to find out the critical loading. HL-93 loading comes out to be the most critical loading and where this loading is not critical in case of bridge decks; a factor of 1.15 is introduced to make it equivalent with HL-93 -Ioading. SAP-2000 (Structural Engineering Services of Pakistan) and MS-Excel is employed for analysis of bridge superstructure subjected to this loading. Internal forces are obtained for the structural elements of the bridge for all traffic loadings mentioned. It is concluded that HL-93 loading can be used for the design of prestressed concrete girder bridge. Bridge design authorities like NHA (National Highway Authority) and different cities development authorities are using different standard traffic loadings. A number of suggestions are made from the results of the research work related to traffic loadings and method of design. These recommendations may be

  2. Mapping critical loads in Europe in the framework of the UN/CEE

    International Nuclear Information System (INIS)

    Hettelingh, J.P.

    1993-01-01

    Critical loads for acidity, sulphur and nitrogen have been computed and geographically mapped in Europe. Critical loads are compared to actual deposition of acidity and of sulphur. Results show that parts of central and north-west Europe receive 20 times or more acidity than the ecosystems' critical loads, thus affecting the long-term sustainability. The Regional Acidification INformation and Simulation model (RAINS) is used to assess 2 scenarios of emission reduction. The first scenario describes currently applied reductions whereas the second assesses the application of maximum feasible reductions to SO 2 and NO x . The latter scenario significantly reduces the area of Europe where critical loads are exceeded. In general, it is shown that a pan-european policy is of highest necessity for obtaining an efficient reduction of acidic emissions throughout Europe. For France, in particular, it is concluded that the excess of critical loads for acidity is largely due to ammonia

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

    African Journals Online (AJOL)

    user

    3.1 Maximum range selection of input and output variables: ..... Wong K. P., Li A., and Law M.Y., “ Advanced Constrained Genetic Algorithm Load Flow Method”, IEE Proc. ... Dr. Parimal Acharjee passed B.E.E. from North Bengal University ...

  4. Preliminary simulation studies of accelerator cavity loading

    International Nuclear Information System (INIS)

    Faehl, R.J.

    1980-06-01

    Two-dimensional simulations of loading effects in a 350 MHz accelerator cavity have been performed. Electron currents of 1-10 kA have been accelerated in 5 MV/m fields. Higher order cavity modes induced by the beam may lead to emittance growth. Operation in an autoaccelerator mode has been studied

  5. Time domain simulations of beam-loading

    International Nuclear Information System (INIS)

    Koscielniak, S.

    1989-09-01

    We present the results of computer simulations of high current beam loading in a proton storage ring. The model integrates the differential equation for gap voltage, and iterates the difference equations for particle longitudinal motion. The effects of cavity fields on the bunch shape and of the fundamental component of the beam on the cavity are treated in a self-consistent manner. The simulation model is applied to verify the dipole-quadrupole hybrid Robinson instability criterion, which differs from the dipole-mode criterion

  6. Loading relativistic Maxwell distributions in particle simulations

    International Nuclear Information System (INIS)

    Zenitani, Seiji

    2015-01-01

    Numerical algorithms to load relativistic Maxwell distributions in particle-in-cell (PIC) and Monte-Carlo simulations are presented. For stationary relativistic Maxwellian, the inverse transform method and the Sobol algorithm are reviewed. To boost particles to obtain relativistic shifted-Maxwellian, two rejection methods are proposed in a physically transparent manner. Their acceptance efficiencies are ≈50% for generic cases and 100% for symmetric distributions. They can be combined with arbitrary base algorithms

  7. Loading relativistic Maxwell distributions in particle simulations

    Energy Technology Data Exchange (ETDEWEB)

    Zenitani, Seiji, E-mail: seiji.zenitani@nao.ac.jp [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

    2015-04-15

    Numerical algorithms to load relativistic Maxwell distributions in particle-in-cell (PIC) and Monte-Carlo simulations are presented. For stationary relativistic Maxwellian, the inverse transform method and the Sobol algorithm are reviewed. To boost particles to obtain relativistic shifted-Maxwellian, two rejection methods are proposed in a physically transparent manner. Their acceptance efficiencies are ≈50% for generic cases and 100% for symmetric distributions. They can be combined with arbitrary base algorithms.

  8. Loading relativistic Maxwell distributions in particle simulations

    Science.gov (United States)

    Zenitani, S.

    2015-12-01

    In order to study energetic plasma phenomena by using particle-in-cell (PIC) and Monte-Carlo simulations, we need to deal with relativistic velocity distributions in these simulations. However, numerical algorithms to deal with relativistic distributions are not well known. In this contribution, we overview basic algorithms to load relativistic Maxwell distributions in PIC and Monte-Carlo simulations. For stationary relativistic Maxwellian, the inverse transform method and the Sobol algorithm are reviewed. To boost particles to obtain relativistic shifted-Maxwellian, two rejection methods are newly proposed in a physically transparent manner. Their acceptance efficiencies are 􏰅50% for generic cases and 100% for symmetric distributions. They can be combined with arbitrary base algorithms.

  9. Potential nitrogen critical loads for northern Great Plains grassland vegetation

    Science.gov (United States)

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

    2015-01-01

    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

  10. Insensitivity of proportional fairness in critically loaded bandwidth sharing networks

    NARCIS (Netherlands)

    Vlasiou, M.; Zhang, J.; Zwart, B.

    2014-01-01

    Proportional fairness is a popular service allocation mechanism to describe and analyze the performance of data networks at flow level. Recently, several authors have shown that the invariant distribution of such networks admits a product form distribution under critical loading. Assuming

  11. Critical loads for vegetation. Definition, use and limits

    International Nuclear Information System (INIS)

    Thimonier, A.; Dupouey, J.L.

    1993-01-01

    Vegetation is a key compartment of ecosystems. It contains a large part of the biodiversity at the species level. For the evaluation of critical loads, we have to separate different receptors: lower plants (algae, fungi, lichens and mosses) and vascular plants. Trees must be distinguished due to their economic value. We analyze the different changes that pollution produces on vegetation: the state of health of individuals, changes in the biology and genetics at the population level, changes in the biodiversity or the specific composition at the community level. Calculation of critical loads is based on observational or experimental studies, in more or less controlled environments. However, they cannot yet be obtained through models of vegetation changes. Some results have been acquired at the European level, mainly for critical loads for nitrogen, but these results have come mostly from Northern Europe. Moreover, only heathlands and acidic forests have been studied in depth. Critical loads for a lot of environment types are still unknown. Lower plants and interactions between vegetation and animals need more investigation

  12. Application of the critical loads approach in South Africa

    CSIR Research Space (South Africa)

    Van Tienhoven, AM

    1995-12-01

    Full Text Available , South Africa. Abstract. South Africa is the most industrialised country in southern Africa and stands at some risk from negative pollution i apa~ To the authors' knowledge, this paper presents the first attempt toapply the critical loads approach...

  13. 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.

    2004-01-01

    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

  14. 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.

    1995-01-01

    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

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    solution tended to be related to less favourable nutritional status. Context Forests have been exposed to elevated atmospheric deposition of acidifying and eutrophying sulphur and nitrogen compounds for decades. Critical loads have been identified, below which damage due to acidification and eutrophication...... 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....

  16. Eutrophic lichens respond to multiple forms of N: implications for critical levels and critical loads research

    Science.gov (United States)

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

    2012-01-01

    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...

  17. 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.

    2015-01-01

    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

  18. A second simulated criticality accident dosimetry experiment

    CERN Document Server

    Adams, N

    1973-01-01

    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...

  19. 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

    2002-01-01

    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

  20. Identification of critical equipment and determination of operational limits in helium refrigerators under pulsed heat load

    Science.gov (United States)

    Dutta, Rohan; Ghosh, Parthasarathi; Chowdhury, Kanchan

    2014-01-01

    Large-scale helium refrigerators are subjected to pulsed heat load from tokamaks. As these plants are designed for constant heat loads, operation under such varying load may lead to instability in plants thereby tripping the operation of different equipment. To understand the behavior of the plant subjected to pulsed heat load, an existing plant of 120 W at 4.2 K and another large-scale plant of 18 kW at 4.2 K have been analyzed using a commercial process simulator Aspen Hysys®. A similar heat load characteristic has been applied in both quasi steady state and dynamic analysis to determine critical stages and equipment of these plants from operational point of view. It has been found that the coldest part of both the cycles consisting JT-stage and its preceding reverse Brayton stage are the most affected stages of the cycles. Further analysis of the above stages and constituting equipment revealed limits of operation with respect to variation of return stream flow rate resulted from such heat load variations. The observations on the outcome of the analysis can be used for devising techniques for steady operation of the plants subjected to pulsed heat load.

  1. Structural Flight Loads Simulation Capability. Volume I.

    Science.gov (United States)

    1980-11-01

    actuators. Load cells sense the resulting loads and give the console operator a positive readout of the loads being applied. The operator’s console...qialn StesSa We Elmn 57. .......... C ’D D .... .. .-- --- -.. ... . ..114 .. ETF’ ’IFEFI,--EIJT :_I’F3L- EL4 ?O cl l c...3.20. (concluded). 127 ra E j214 CbC ob) C-H ea) 4p U) ’-4 r4 128 EL4 UA f r c www aw r. 0 ag 0 . 0 mo > 4-) 0 .4-) en 010 44 1*5 1 I .IA U * . a) Z

  2. Calculation and mapping of critical loads in Europe: Status report 1993

    International Nuclear Information System (INIS)

    Downing, R.J.; Hettelingh, J.P.; De Smet, P.A.M.

    1993-01-01

    The work of the RIVM Coordination Center for Effects (CCE) and National Focal Centers (NFCs) for Mapping over the past two years is summarized. The primary task of the critical loads mapping program during this period was to compute and map critical loads of sulphur in Europe. Efforts were undertaken to enhance the scientific foundations and policy relevance of the critical load program, and to foster consensus among producers and users of this information by means of three workshops. The applied calculation methods are described, as well as the resulting critical loads maps, based upon the outcomes of the workshops. Chapter 2 contains the most recent maps (May 1993) of the critical load of acidity as well as the critical load of sulphur and critical sulphur deposition, which are derived from the critical load of acidity. The chapter also contains maps of the sulphur deposition in Europe in 1980 and 1990, and the resulting exceedances. In chapter 3 the methods and equations used to derive the maps of critical loads and exceedances of acidity and sulphur are described with emphasis on the advances in the calculation methods used since the first European critical loads maps were produced in 1991. In chapter 4 the methods to be used to compute and map critical loads in the future are presented. In chapter 5 an overview of the data inputs is given, and the methods of data handling performed by the CCE to produce the current European maps of critical loads. In chapter 6 the results of an uncertainty analysis is described, which was performed on the critical loads computation methodology to assess the reliability of the computation results and the importance of the various input variables. Chapter 7 provides some conclusions and recommendations resulting from the critical load mapping activities. In Appendix 1 the reports of the can be found, with additional maps of critical loads and background variables in Appendix 2. 15 figs., 11 tabs., 156 refs

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

    Directory of Open Access Journals (Sweden)

    Pawel Wysmulski

    2017-09-01

    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.

  4. Simulated annealing approach for solving economic load dispatch ...

    African Journals Online (AJOL)

    user

    thermodynamics to solve economic load dispatch (ELD) problems. ... evolutionary programming algorithm has been successfully applied for solving the ... concept behind the simulated annealing (SA) optimization is discussed in Section 3.

  5. Measuring cognitive load: performance, mental effort and simulation task complexity.

    Science.gov (United States)

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

    2015-08-01

    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 load among novices engaged in simulation-based learning. These measures can be used to track 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.

  6. New approaches to provide ride-through for critical loads in electric power distribution systems

    Science.gov (United States)

    Montero-Hernandez, Oscar C.

    2001-07-01

    The extensive use of electronic circuits has enabled modernization, automation, miniaturization, high quality, low cost, and other achievements regarding electric loads in the last decades. However, modern electronic circuits and systems are extremely sensitive to disturbances from the electric power supply. In fact, the rate at which these disturbances happen is considerable as has been documented in recent years. In response to the power quality concerns presented previously, this dissertation is proposing new approaches to provide ride-through for critical loads during voltage disturbances with emphasis on voltage sags. In this dissertation, a new approach based on an AC-DC-AC system is proposed to provide ride-through for critical loads connected in buildings and/or an industrial system. In this approach, a three-phase IGBT inverter with a built in Dc-link voltage regulator is suitably controlled along with static by-pass switches to provide continuous power to critical loads. During a disturbance, the input utility source is disconnected and the power from the inverter is connected to the load. The remaining voltage in the AC supply is converted to DC and compensated before being applied to the inverter and the load. After detecting normal utility conditions, power from the utility is restored to the critical load. In order to achieve an extended ride-through capability a second approach is introduced. In this case, the Dc-link voltage regulator is performed by a DC-DC Buck-Boost converter. This new approach has the capability to mitigate voltage variations below and above the nominal value. In the third approach presented in this dissertation, a three-phase AC to AC boost converter is investigated. This converter provides a boosting action for the utility input voltages, right before they are applied to the load. The proposed Pulse Width Modulation (PWM) control strategy ensures independent control of each phase and compensates for both single-phase or poly

  7. COTRANSA simulation of Chinshan unit one generator load rejection test

    International Nuclear Information System (INIS)

    Wu, C.H.

    1984-01-01

    A simulation of the plant behavior during a BWR generator load rejection transient using Exxon Nuclear Company's COTRANSA code is presented in this paper. The results are compared to measurements obtained by Taiwan Power Company during a generator load rejection transient, initiated at full power condition, which was one of the Chinshan Unit 1 initial cycle startup tests. Good agreement between the COTRANSA predicted and the measured values, indicates that the COTRANSA code can simulate this transient satisfactorily

  8. Optimized Loading for Particle-in-cell Gyrokinetic Simulations

    International Nuclear Information System (INIS)

    Lewandowski, J.L.V.

    2004-01-01

    The problem of particle loading in particle-in-cell gyrokinetic simulations is addressed using a quadratic optimization algorithm. Optimized loading in configuration space dramatically reduces the short wavelength modes in the electrostatic potential that are partly responsible for the non-conservation of total energy; further, the long wavelength modes are resolved with good accuracy. As a result, the conservation of energy for the optimized loading is much better that the conservation of energy for the random loading. The method is valid for any geometry and can be coupled to optimization algorithms in velocity space

  9. Simulation of load traffic and steeped speed control of conveyor

    Science.gov (United States)

    Reutov, A. A.

    2017-10-01

    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.

  10. Cognitive load predicts point-of-care ultrasound simulator performance.

    Science.gov (United States)

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

    2018-02-01

    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.

  11. Application for position and load reference generation of a simulated ...

    African Journals Online (AJOL)

    Application for position and load reference generation of a simulated ... generation for a motor stand simulating a mechatronic chain, in this case a three degree of ... in position as the robot joint actuators coupled with three controlled in torque, ...

  12. 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.

    2013-01-01

    In analyzing stochastic dynamic systems, analysis of the system uncertainty due to randomness in the loads plays a crucial role. Typically time series of the stochastic loads are simulated using traditional random phase method. This approach combined with fast Fourier transform algorithm makes...... 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...

  13. 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)

    1997-12-31

    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

  14. Wind Simulation for Extreme and Fatigue Loads

    DEFF Research Database (Denmark)

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

    2003-01-01

    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...... 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......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...

  15. 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)

    2015-11-30

    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.

  16. A dynamic modelling approach for estimating critical loads of nitrogen based on plant community changes under a changing climate

    International Nuclear Information System (INIS)

    Belyazid, Salim; Kurz, Dani; Braun, Sabine; Sverdrup, Harald; Rihm, Beat; Hettelingh, Jean-Paul

    2011-01-01

    A dynamic model of forest ecosystems was used to investigate the effects of climate change, atmospheric deposition and harvest intensity on 48 forest sites in Sweden (n = 16) and Switzerland (n = 32). The model was used to investigate the feasibility of deriving critical loads for nitrogen (N) deposition based on changes in plant community composition. The simulations show that climate and atmospheric deposition have comparably important effects on N mobilization in the soil, as climate triggers the release of organically bound nitrogen stored in the soil during the elevated deposition period. Climate has the most important effect on plant community composition, underlining the fact that this cannot be ignored in future simulations of vegetation dynamics. Harvest intensity has comparatively little effect on the plant community in the long term, while it may be detrimental in the short term following cutting. This study shows: that critical loads of N deposition can be estimated using the plant community as an indicator; that future climatic changes must be taken into account; and that the definition of the reference deposition is critical for the outcome of this estimate. - Research highlights: → Plant community changes can be used to estimate critical loads of nitrogen. → Climate change is decisive for future changes of geochemistry and plant communities. → Climate change cannot be ignored in estimates of critical loads. → The model ForSAFE-Veg was successfully used to set critical loads of nitrogen. - Plant community composition can be used in dynamic modelling to estimate critical loads of nitrogen deposition, provided the appropriate reference deposition, future climate and target plant communities are defined.

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

    African Journals Online (AJOL)

    HP

    Considering the widespread use of this type of structure and the critical role it ... proposed by the model for the critical buckling load of self- supporting lattice tower, whose equivalent solid beam- ... stiffness, both material and geometric, [5, 6].

  18. Heat load material studies: Simulated tokamak disruptions

    International Nuclear Information System (INIS)

    Gahl, J.M.; McDonald, J.M.; Zakharov, A.; Tserevitinov, S.; Barabash, V.; Guseva, M.

    1991-01-01

    It is clear that an improved understanding of the effects of tokamak disruptions on plasma facing component materials is needed for the ITER program. very large energy fluxes are predicted to be deposited in ITER and could be very damaging to the machine. During 1991, Sandia National Laboratories and the University of New Mexico conducted cooperative tokamak disruption simulation experiments at several Soviet facilities. These facilities were located at the Efremov Institute in Leningrad, the Kurchatov Atomic Energy Institute (Troisk and Moscow) and the Institute for Physical Chemistry of the Soviet Adademy of Sciences in Moscow. Erosion of graphite from plasma stream impact is seen to be much less than that observed with laser or electron beams with similar energy fluxes. This, along with other data obtained, seem to suggest that the ''vapor shielding'' effect is a very important phenomenon in the study of graphite erosion during tokamak disruption

  19. Numerical simulation of wire array load implosion on Yang accelerator

    International Nuclear Information System (INIS)

    Zhao Hailong; Deng Jianjun; Wang Qiang; Zou Wenkang; Wang Ganghua

    2012-01-01

    Based on the ZORK model describing the Saturn facility, a zero dimensional load model of the wire array Z-pinch on Yang accelerator is designed using Pspice to simulate the implosion process. Comparisons between the calculated results and experimental data prove the load model to be correct. The applicability and shortcomings of the load model are presented. One-dimensional magnetohydrodynamic calculations are performed by using the current curve obtained from calculated results of experiment Yang 1050#. and the parameters such as implosion time and radiation X-ray power are obtained. (authors)

  20. Comparing CTH simulations and experiments on explosively loaded rings

    Science.gov (United States)

    Braithwaite, C. H.; Aydelotte, Brady; Collins, Adam; Thadhani, Naresh; Williamson, David Martin

    2012-03-01

    A series of experiments were conducted on explosively loaded metallic rings for the purpose of studying fragmentation. In addition to the collection of fragments for analysis, the radial velocity of the expanding ring was measured with photon Doppler velocimetry (PDV) and the arrangement was imaged using high speed photography. Both the ring material and the material used as the explosive container were altered and the results compared with simulations performed in CTH. Good agreement was found between the simulations and the experiments. The maximum radial velocity attained was approximately 380 m/s, which was achieved through loading with a 5g PETN based charge.

  1. 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

    2016-01-01

    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...

  2. Critical loads as a policy tool for protecting ecosystems from the effects of air pollutants

    Science.gov (United States)

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

    2008-01-01

    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...

  3. Estimates of critical acid loads and exceedances for forest soils across the conterminous United States

    Science.gov (United States)

    Steven G. McNulty; Erika C. Cohen; Jennifer A. Moore Myers; Timothy J. Sullivan; Harbin Li

    2007-01-01

    Concern regarding the impacts of continued nitrogen and sulfur deposition on ecosystem health has prompted the development of critical acid load assessments for forest soils. A critical acid load is a quantitative estimate of exposure to one or more pollutants at or above which harmful acidification-related effects on sensitive elements of the environment occur. A...

  4. A conceptual framework: redifining forests soil's critical acid loads under a changing climate

    Science.gov (United States)

    Steven G. McNulty; Johnny L. Boggs

    2010-01-01

    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...

  5. Emotion, cognitive load and learning outcomes during simulation training.

    Science.gov (United States)

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

    2012-11-01

    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

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

    Science.gov (United States)

    Yu, K.; Samulyak, R.; Yonehara, K.; Freemire, B.

    2018-01-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Yu, K. [Brookhaven National Lab. (BNL), Upton, NY (United States). Computational Science Initiative; Samulyak, R. [Brookhaven National Lab. (BNL), Upton, NY (United States). Computational Science Initiative; Stony Brook Univ., NY (United States). Dept. of Applied Mathematics and Statistics; Yonehara, K. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Freemire, B. [Northern Illinois Univ., DeKalb, IL (United States)

    2018-01-11

    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 also been performed in the range of parameters typical for practical muon cooling channels.

  8. Machine Learning of the Reactor Core Loading Pattern Critical Parameters

    Directory of Open Access Journals (Sweden)

    Krešimir Trontl

    2008-01-01

    Full Text Available The usual approach to loading pattern optimization involves high degree of engineering judgment, a set of heuristic rules, an optimization algorithm, and a computer code used for evaluating proposed loading patterns. The speed of the optimization process is highly dependent on the computer code used for the evaluation. In this paper, we investigate the applicability of a machine learning model which could be used for fast loading pattern evaluation. We employ a recently introduced machine learning technique, support vector regression (SVR, which is a data driven, kernel based, nonlinear modeling paradigm, in which model parameters are automatically determined by solving a quadratic optimization problem. The main objective of the work reported in this paper was to evaluate the possibility of applying SVR method for reactor core loading pattern modeling. We illustrate the performance of the solution and discuss its applicability, that is, complexity, speed, and accuracy.

  9. Machine Learning of the Reactor Core Loading Pattern Critical Parameters

    International Nuclear Information System (INIS)

    Trontl, K.; Pevec, D.; Smuc, T.

    2008-01-01

    The usual approach to loading pattern optimization involves high degree of engineering judgment, a set of heuristic rules, an optimization algorithm, and a computer code used for evaluating proposed loading patterns. The speed of the optimization process is highly dependent on the computer code used for the evaluation. In this paper, we investigate the applicability of a machine learning model which could be used for fast loading pattern evaluation. We employ a recently introduced machine learning technique, support vector regression (SVR), which is a data driven, kernel based, nonlinear modeling paradigm, in which model parameters are automatically determined by solving a quadratic optimization problem. The main objective of the work reported in this paper was to evaluate the possibility of applying SVR method for reactor core loading pattern modeling. We illustrate the performance of the solution and discuss its applicability, that is, complexity, speed, and accuracy

  10. Static load simulation of steering knuckle for a formula student race car

    Science.gov (United States)

    Saputro, Bagus Aulia; Ubaidillah, Triono, Dicky Agus; Pratama, Dzaky Roja; Cahyono, Sukmaji Indro; Imaduddin, Fitrian

    2018-02-01

    This research aims to determine the stress distribution which occurs on the steering knuckle and to define its safety factor number. Steering knuckle is the most critical part of a car's steering system. Steering knuckle supports the tie rod, brake caliper, and the wheels to provide stability. Steering knuckle withstands the load which given on the front wheels and functions as the wheel's axis. Balljoint and king support the rotation of the suspension arm. When the car is in idle position, knuckle hold the weight of the car, it gets braking force when it's braking and cornering. Knuckle is designed to have the strength that could withstand load and to have a good safety factor value. Knuckle is designed using Fusion software then simulated using Fusion simulation software with a static load, moment braking force, and cornering force as the loads in this simulation. The simulation works in ideal condition. The result of this simulation is satisfying. This simulation produces a maximum displacement of 0.01281mm, the maximum shear stress is 3.707 MPa on the stub hole, and the safety factor is 5.24. The material used for this product is mild steel AISI 1018.

  11. [Mapping Critical Loads of Heavy Metals for Soil Based on Different Environmental Effects].

    Science.gov (United States)

    Shi, Ya-xing; Wu, Shao-hua; Zhou, Sheng-lu; Wang, Chun-hui; Chen, Hao

    2015-12-01

    China's rapid development of industrialization and urbanization causes the growing problem of heavy metal pollution of soil, threatening environment and human health. Therefore, prevention and management of heavy metal pollution become particularly important. Critical loads of heavy metals are an important management tool that can be utilized to prevent the occurrence of heavy metal pollution. Our study was based on three cases: status balance, water environmental effects and health risks. We used the steady-state mass balance equation to calculate the critical loads of Cd, Cu, Pb, Zn at different effect levels and analyze the values and spatial variation of critical loads. In addition, we used the annual input fluxes of heavy metals of the agro-ecosystem in the Yangtze River delta and China to estimate the proportion of area with exceedance of critical loads. The results demonstrated that the critical load value of Cd was the minimum, and the values of Cu and Zn were lager. There were spatial differences among the critical loads of four elements in the study area, lower critical loads areas mainly occurred in woodland and high value areas distributed in the east and southwest of the study area, while median values and the medium high areas mainly occurred in farmland. Comparing the input fluxes of heavy metals, we found that Pb and Zn in more than 90% of the area exceeded the critical loads under different environmental effects in the study area. The critical load exceedance of Cd mainly occurred under the status balance and the water environmental effect, while Cu under the status balance and water environmental effect with a higher proportion of exceeded areas. Critical loads of heavy metals at different effect levels in this study could serve as a reference from effective control of the emissions of heavy metals and to prevent the occurrence of heavy metal pollution.

  12. Prediction calculation of HTR-10 fuel loading for the first criticality

    International Nuclear Information System (INIS)

    Jing Xingqing; Yang Yongwei; Gu Yuxiang; Shan Wenzhi

    2001-01-01

    The 10 MW high temperature gas cooled reactor (HTR-10) was built at Institute of Nuclear Energy Technology, Tsinghua University, and the first criticality was attained in Dec. 2000. The high temperature gas cooled reactor physics simulation code VSOP was used for the prediction of the fuel loading for HTR-10 first criticality. The number of fuel element and graphite element was predicted to provide reference for the first criticality experiment. The prediction calculations toke into account the factors including the double heterogeneity of the fuel element, buckling feedback for the spectrum calculation, the effect of the mixture of the graphite and the fuel element, and the correction of the diffusion coefficients near the upper cavity based on the transport theory. The effects of impurities in the fuel and the graphite element in the core and those in the reflector graphite on the reactivity of the reactor were considered in detail. The first criticality experiment showed that the predicted values and the experiment results were in good agreement with little relative error less than 1%, which means the prediction was successful

  13. SIMULATED CHARACTERISTICS OF PATCH ANTENNA LOADED WITH SRRs

    OpenAIRE

    Debasis Mishra; G. Arun Kumar; D. R. Poddar; R. K. Mishra

    2010-01-01

    This article investigates, from electromagnetic simulation, the effects on gain and efficiency of a patch antenna loaded with split ring resonators. It is observed that it leads to lowering of resonant frequency; some mismatch resulting in a slight degradation of the impedance bandwidth and improvement of gain and efficiency.

  14. FEM simulation of static loading test of the Omega beam

    Science.gov (United States)

    Bílý, Petr; Kohoutková, Alena; Jedlinský, Petr

    2017-09-01

    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.

  15. Machine learning of the reactor core loading pattern critical parameters

    International Nuclear Information System (INIS)

    Trontl, K.; Pevec, D.; Smuc, T.

    2007-01-01

    The usual approach to loading pattern optimization involves high degree of engineering judgment, a set of heuristic rules, an optimization algorithm and a computer code used for evaluating proposed loading patterns. The speed of the optimization process is highly dependent on the computer code used for the evaluation. In this paper we investigate the applicability of a machine learning model which could be used for fast loading pattern evaluation. We employed a recently introduced machine learning technique, Support Vector Regression (SVR), which has a strong theoretical background in statistical learning theory. Superior empirical performance of the method has been reported on difficult regression problems in different fields of science and technology. SVR is a data driven, kernel based, nonlinear modelling paradigm, in which model parameters are automatically determined by solving a quadratic optimization problem. The main objective of the work reported in this paper was to evaluate the possibility of applying SVR method for reactor core loading pattern modelling. The starting set of experimental data for training and testing of the machine learning algorithm was obtained using a two-dimensional diffusion theory reactor physics computer code. We illustrate the performance of the solution and discuss its applicability, i.e., complexity, speed and accuracy, with a projection to a more realistic scenario involving machine learning from the results of more accurate and time consuming three-dimensional core modelling code. (author)

  16. Systems modeling and simulation applications for critical care medicine

    Science.gov (United States)

    2012-01-01

    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

  17. Systems modeling and simulation applications for critical care medicine.

    Science.gov (United States)

    Dong, Yue; Chbat, Nicolas W; Gupta, Ashish; Hadzikadic, Mirsad; Gajic, Ognjen

    2012-06-15

    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.

  18. Electromagnetic simulations of simple models of ferrite loaded kickers

    CERN Document Server

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

    2010-01-01

    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.

  19. Critical loads of nitrogen deposition and critical levels of atmospheric ammonia for semi-natural Mediterranean evergreen woodlands

    Directory of Open Access Journals (Sweden)

    P. Pinho

    2012-03-01

    Full Text Available Nitrogen (N has emerged in recent years as a key factor associated with global changes, with impacts on biodiversity, ecosystems functioning and human health. In order to ameliorate the effects of excessive N, safety thresholds such as critical loads (deposition fluxes and levels (concentrations can be established. Few studies have assessed these thresholds for semi-natural Mediterranean ecosystems. Our objective was therefore to determine the critical loads of N deposition and long-term critical levels of atmospheric ammonia for semi-natural Mediterranean evergreen woodlands. We have considered changes in epiphytic lichen communities, one of the most sensitive comunity indicators of excessive N in the atmosphere. Based on a classification of lichen species according to their tolerance to N we grouped species into response functional groups, which we used as a tool to determine the critical loads and levels. This was done for a Mediterranean climate in evergreen cork-oak woodlands, based on the relation between lichen functional diversity and modelled N deposition for critical loads and measured annual atmospheric ammonia concentrations for critical levels, evaluated downwind from a reduced N source (a cattle barn. Modelling the highly significant relationship between lichen functional groups and annual atmospheric ammonia concentration showed the critical level to be below 1.9 μg m−3, in agreement with recent studies for other ecosystems. Modelling the highly significant relationship between lichen functional groups and N deposition showed that the critical load was lower than 26 kg (N ha−1 yr−1, which is within the upper range established for other semi-natural ecosystems. Taking into account the high sensitivity of lichen communities to excessive N, these values should aid development of policies to protect Mediterranean woodlands from the initial effects of excessive N.

  20. Power analysis and simulation of a vehicle under combined loads

    International Nuclear Information System (INIS)

    Khayyam, H.; Kouzani, A.Z.; Khoshmanesh, K.; Hu, E.

    2008-01-01

    Reducing fuel consumption in vehicles offers many obvious economic benefits, and also helps reduce air pollution emission levels. Mechanical engineers and automotive researches have continuously searched for ways to optimize fuel consumption in vehicles. This paper presented an analytical model of fuel consumption (AMFC) in an effort to coordinate the driving power and manage the overall fuel consumption for an internal combustion engine vehicle. The model calculated the different loads applied on the vehicle, such as road-slope, road-friction, wind-drag, accessories, and mechanical losses. It also solved the combustion equation of the engine under different working conditions including various fuel compositions, excess airs and air inlet temperatures. The model then determined the contribution of each load to signify the energy distribution and power flows of the vehicle. In order to assess the model's sensitivity to different loads, the following four simulations were conducted: flat-windless, flat-windy, sloppy-windless, sloppy-windy. The average fuel consumption for the four simulations was presented. The paper outlined the specification of the vehicle and environment as well as the simulation methodology. The model, algorithm, slope simulation, and drive strategy were presented. It was concluded that the power consumption significantly increased where the slope friction came into play and that the model has the potential to assist in vehicle energy management. 16 refs., 4 tabs., 14 figs

  1. Development of training simulator based on critical assemblies test bench

    International Nuclear Information System (INIS)

    Narozhnyi, A.T.; Vorontsov, S.V.; Golubeva, O.A.; Dyudyaev, A.M.; Il'in, V.I.; Kuvshinov, M.I.; Panin, A.V.; Peshekhonov, D.P.

    2007-01-01

    When preparing critical mass experiment, multiplying system (MS) parts are assembled manually. This work is connected with maximum professional risk to personnel. Personnel training and keeping the skill of working experts is the important factor of nuclear safety maintenance. For this purpose authors develop a training simulator based on functioning critical assemblies test bench (CATB), allowing simulation of the MS assemblage using training mockups made of inert materials. The control program traces the current status of MS under simulation. A change in the assembly neutron physical parameters is mapped in readings of the regular devices. The simulator information support is provided by the computer database on physical characteristics of typical MS components The work in the training mode ensures complete simulation of real MS assemblage on the critical test bench. It makes it possible to elaborate the procedures related to CATB operation in a standard mode safely and effectively and simulate possible abnormal situations. (author)

  2. Numerical Simulation of the Kinetic Critical Nucleus

    OpenAIRE

    Sanada, Masaaki; Nishioka, Kazumi; Okada, Masahumi; Maksimov, Igor, L.

    1997-01-01

    Our main interest is to see whether the number density indicates a peak at the kinetically stable critical nucleus due to its kinetical stability. We have numerically calculated the time evolution of the number densities of clusters in the case of water vapor nucleation. We employ the condition in which the difference between the size of the thermodynamic crtitical nucleus and that of the kinetic one is appreciable. The results show that the peak does not appear in the number densities of clu...

  3. The asymptotic variance of departures in critically loaded queues

    NARCIS (Netherlands)

    Al Hanbali, Ahmad; Mandjes, M.R.H.; Nazarathy, Y.; Whitt, W.

    2011-01-01

    We consider the asymptotic variance of the departure counting process D(t) of the GI/G/1 queue; D(t) denotes the number of departures up to time t. We focus on the case where the system load ϱ equals 1, and prove that the asymptotic variance rate satisfies limt→∞varD(t) / t = λ(1 - 2 / π)(ca2 +

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

    DEFF Research Database (Denmark)

    Larsen, Torben J.; Aagaard Madsen, Helge

    2013-01-01

    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...... 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...... Turbines (HAWT’s), are discussed regarding the application to VAWT’s. Further on a small section regarding aerodynamic flow in curved motion is included....

  5. Fast core prediction simulator for load follow control

    International Nuclear Information System (INIS)

    Yim, Man Sung; Lee, Sang Hoon; Lee, Un Chul

    1990-01-01

    An operator-assisting system for the reactor core control under power changing operating condition was developed. The system is consisted of core simulator routine and Xenon and Iodine initial condition generation routine. The initial condition generation routine, without exactly knowing the core status, is capable of providing accurate number densities and axial offset conditions of Xenon and Iodine after several hours of predictor- corrector calculations using the plant instrumentation signals of power level and power axial offset. The core simulator routine, even with the two node core model, gives equivalently accurate results as the one-dimensional model for the core behaviour simulation under power changing condition and can provide proper control strategies for load follow operation. The core simulator can also be used by the operator to develop remedial actions to restore the distorted power distribution by using its prediction capability

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

    NARCIS (Netherlands)

    Kalz, Marco

    2014-01-01

    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.

  7. Determination of the critical plane and durability estimation for a multiaxial cyclic loading

    Science.gov (United States)

    Burago, N. G.; Nikitin, A. D.; Nikitin, I. S.; Yakushev, V. L.

    2018-03-01

    An analytical procedure is proposed to determine the critical plane orientation according to the Findley criterion for the multiaxial cyclic loading. The cases of in-phase and anti-phase cyclic loading are considered. Calculations of the stress state are carried out for the system of the gas turbine engine compressor disk and blades for flight loading cycles. The formulas obtained are used for estimations of the fatigue durability of this essential element of structure.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-08-01

    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.

  9. Fundamental simulations of transverse load effects on Nb3Sn strands using finite element analysis

    Science.gov (United States)

    Wang, T.; Chiesa, L.; Takayasu, M.

    2012-06-01

    A 2D finite element elasto-plastic analysis with various property values of the materials in composite Nb3Sn wires has been conducted to simulate the transverse compression effect on a single strand and a 3-strand cable as basic elements of a Cable-in-Conduit Conductor (CICC). The simulation results have been compared with previously reported experimental results. A parametric study of the stress-strain characteristics of copper at 4 K was considered. The simulation results showed that wire and cable deformations due to the transverse load are very sensitive to the elasto-plastic material properties of copper and bronze. In a triplet it is found that the strain distributions inside the superconducting strand are very different along its axis, that is, for a configuration in which two strands lined in parallel to the transverse load direction shows much higher internal strain than other configurations under the same transverse load. The simulation results agree with the reported experimental results indicating a low Young's modulus for Nb3Sn wires under transverse compression. The simulation also supports the reported contact mechanics model for critical current degradation.

  10. Investigating the critical slowing down of QCD simulations

    International Nuclear Information System (INIS)

    Schaefer, Stefan

    2009-12-01

    Simulations of QCD are known to suffer from serious critical slowing down towards the continuum limit. This is particularly prominent in the topological charge. We investigate the severeness of the problem in the range of lattice spacings used in contemporary simulations and propose a method to give more reliable error estimates. (orig.)

  11. 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.

    2018-01-01

    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.

  12. Computer modeling of road bridge for simulation moving load

    Directory of Open Access Journals (Sweden)

    Miličić Ilija M.

    2016-01-01

    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. .

  13. Air pollution and impact on eco-systems. Load concept/critical level and its consequences

    International Nuclear Information System (INIS)

    Elichegaray, C.

    1993-01-01

    Critical loads and critical levels respectively can be defined as the deposition value, or the concentration of pollutants in the atmosphere, above which adverse effects on receptors such as plants, ecosystems, materials may occur. Important research is currently being developed on critical loads and levels in the framework of the Geneva convention on transboundary air pollution. Several binding protocols have been elaborated between the european countries, the Canada, and the USA, to reduce their emissions of sulphur, nitrogen oxides, volatile organic compounds. This article describes the critical loads and levels approach, and the way by which this concept is now used for the revision of the sulphur protocol. (author). 6 refs., 5 figs., 4 tabs

  14. Microcrack propagation under multiaxial loading - experiment and simulation

    International Nuclear Information System (INIS)

    Poetter, K.; Suhartono, A.; Yousefi, F.; Zenner, H.; Duewel, V.; Schram, A.

    2000-01-01

    The accuracy of lifetime prediction for technical components subjected to cyclic loading is still not satisfying. One essential reason for the deviation between the results of the lifetime calculation and experimental results is that it is not yet possible to generate a model capable to describe the microstructural damage process which occurs in the tested material and to integrate this model in the calculation. All of the present research results recognize that the growth of microcracks is significantly influenced by the microstructure of the material. In order to take into account the influence of the microstructure on the damage process a simulation model is suggested in this paper which considers the local stress state in addition to the random nature of the material structure in the form of grain boundaries and slip systems. The results generated by means of the simulation model are compared and verified with those experiences obtained from multiaxial fatigue testing of the investigated aluminum material. For this purpose the surfaces of the tested specimens are carefully observed to discover and analyze microcracks which are classified according to their number, length, and orientation. Moreover the mechanisms of crack initiation and propagation are major points of interest for the comparison of theoretical and experimental results. The developed computer software is suitable to simulate the microcrack initiation, the propagation and coalescence of microcracks as well as the transition of stage I cracks to stage II cracks for uniaxial and multiaxial loading. Results obtained from the simulation model could be verified with the experiment. The future aim to be emphasized is the utilization of the parameter investigations carried out with the computer simulation model in order to improve the lifetime prediction. (orig.)

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

    Directory of Open Access Journals (Sweden)

    Shaun A. WATMOUGH

    2010-08-01

    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.

  16. Simulation of load-sharing in standalone distributed generation system

    Science.gov (United States)

    Ajewole, Titus O.; Craven, Robert P. M.; Kayode, Olakunle; Babalola, Olufisayo S.

    2018-05-01

    This paper presents a study on load-sharing among the component generating units of a multi-source electric microgrid that is operated as an autonomous ac supply-mode system. Emerging trend in power system development permits deployment of microgrids for standalone or stand-by applications, thereby requiring active- and reactive power sharing among the discrete generating units contained in hybrid-source microgrids. In this study, therefore, a laboratory-scale model of a microgrid energized with three renewable energy-based sources is employed as a simulation platform to investigate power sharing among the power-generating units. Each source is represented by a source emulator that captures the real operational characteristics of the mimicked generating unit and, with implementation of real-life weather data and load profiles on the model; the sharing of the load among the generating units is investigated. There is a proportionate generation of power by the three source emulators, with their frequencies perfectly synchronized at the point of common coupling as a result of balance flow of power among them. This hybrid topology of renewable energy-based microgrid could therefore be seamlessly adapted into national energy mix by the indigenous electric utility providers in Nigeria.

  17. Loading Deformation Characteristic Simulation Study of Engineering Vehicle Refurbished Tire

    Science.gov (United States)

    Qiang, Wang; Xiaojie, Qi; Zhao, Yang; Yunlong, Wang; Guotian, Wang; Degang, Lv

    2018-05-01

    The paper constructed engineering vehicle refurbished tire computer geometry model, mechanics model, contact model, finite element analysis model, did simulation study on load-deformation property of engineering vehicle refurbished tire by comparing with that of the new and the same type tire, got load-deformation of engineering vehicle refurbished tire under the working condition of static state and ground contact. The analysis result shows that change rules of radial-direction deformation and side-direction deformation of engineering vehicle refurbished tire are close to that of the new tire, radial-direction and side-direction deformation value is a little less than that of the new tire. When air inflation pressure was certain, radial-direction deformation linear rule of engineer vehicle refurbished tire would increase with load adding, however, side-direction deformation showed linear change rule, when air inflation pressure was low; and it would show increase of non-linear change rule, when air inflation pressure was very high.

  18. SUPERCOMPUTER SIMULATION OF CRITICAL PHENOMENA IN COMPLEX SOCIAL SYSTEMS

    Directory of Open Access Journals (Sweden)

    Petrus M.A. Sloot

    2014-09-01

    Full Text Available The paper describes a problem of computer simulation of critical phenomena in complex social systems on a petascale computing systems in frames of complex networks approach. The three-layer system of nested models of complex networks is proposed including aggregated analytical model to identify critical phenomena, detailed model of individualized network dynamics and model to adjust a topological structure of a complex network. The scalable parallel algorithm covering all layers of complex networks simulation is proposed. Performance of the algorithm is studied on different supercomputing systems. The issues of software and information infrastructure of complex networks simulation are discussed including organization of distributed calculations, crawling the data in social networks and results visualization. The applications of developed methods and technologies are considered including simulation of criminal networks disruption, fast rumors spreading in social networks, evolution of financial networks and epidemics spreading.

  19. Fuzzy Simulation-Optimization Model for Waste Load Allocation

    Directory of Open Access Journals (Sweden)

    Motahhare Saadatpour

    2006-01-01

    Full Text Available This paper present simulation-optimization models for waste load allocation from multiple point sources which include uncertainty due to vagueness of the parameters and goals. This model employs fuzzy sets with appropriate membership functions to deal with uncertainties due to vagueness. The fuzzy waste load allocation model (FWLAM incorporate QUAL2E as a water quality simulation model and Genetic Algorithm (GA as an optimization tool to find the optimal combination of the fraction removal level to the dischargers and pollution control agency (PCA. Penalty functions are employed to control the violations in the system.  The results demonstrate that the goal of PCA to achieve the best water quality and the goal of the dischargers to use the full assimilative capacity of the river have not been satisfied completely and a compromise solution between these goals is provided. This fuzzy optimization model with genetic algorithm has been used for a hypothetical problem. Results demonstrate a very suitable convergence of proposed optimization algorithm to the global optima.

  20. The scratch test - Different critical load determination techniques. [adhesive strength of thin hard coatings

    Science.gov (United States)

    Sekler, J.; Hintermann, H. E.; Steinmann, P. A.

    1988-01-01

    Different critical load determination techniques such as microscopy, acoustic emission, normal, tangential, and lateral forces used for scratch test evaluation of complex or multilayer coatings are investigated. The applicability of the scratch test to newly developed coating techniques, systems, and applications is discussed. Among the methods based on the use of a physical measurement, acoustic emission detection is the most effective. The dynamics ratio between the signals below and above the critical load for the acoustic emission (much greater than 100) is well above that obtained with the normal, tangential, and lateral forces. The present commercial instruments are limited in load application performance. A scratch tester able to apply accurate loads as low as 0.01 N would probably overcome most of the actual limitations and would be expected to extend the scratch testing technique to different application fields such as optics and microelectronics.

  1. Suppression of the initial transient in Monte Carlo criticality simulations

    International Nuclear Information System (INIS)

    Richet, Y.

    2006-12-01

    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)

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

    Directory of Open Access Journals (Sweden)

    Hans-Dieter Nagel

    2001-01-01

    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.

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

    NARCIS (Netherlands)

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

    2013-01-01

    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

  4. 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.

    1996-01-01

    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.

  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

    2010-09-15

    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. Critical slowing down and error analysis in lattice QCD simulations

    International Nuclear Information System (INIS)

    Schaefer, Stefan; Sommer, Rainer; Virotta, Francesco

    2010-09-01

    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.)

  7. Claire, a simulation and testing tool for critical softwares

    International Nuclear Information System (INIS)

    Gassino, J.; Henry, J.Y.

    1996-01-01

    The CEA and IPSN (Institute of Nuclear Protection and Safety) needs concerning the testing of critical softwares, have led to the development of the CLAIRE tool which is able to test the softwares without modification. This tool allows to graphically model the system and its environment and to include components into the model which observe and do not modify the behaviour of the system to be tested. The executable codes are integrated in the model. The tool uses target machine simulators (microprocessors). The technique used (the event simulation) allows to associate actions with events such as the execution of an instruction, the access to a variable etc.. The simulation results are exploited using graphic, states research and test cover measurement tools. In particular, this tool can give help to the evaluation of critical softwares with pre-existing components. (J.S.)

  8. Simulation of cracks in tungsten under ITER specific heat loads

    International Nuclear Information System (INIS)

    Peschany, S.

    2006-01-01

    The problem of high tritium retention in co-deposited carbon layers on the walls of ITER vacuum chamber motivates investigation of materials for the divertor armour others than carbon fibre composite (CFC). Tungsten is most probable material for CFC replacement as the divertor armour because of high vaporisation temperature and heat conductivity. In the modern ITER design tungsten is a reference material for the divertor cover, except for the separatrix strike point armoured with CFC. As divertor armour, tungsten should withstand severe heat loads at off-normal ITER events like disruptions, ELMs and vertical displacement events. Experiments on tungsten heating with plasma streams and e-beams have shown an intense crack formation at the surface of irradiated sample [ V.I. Tereshin, A.N. Bandura, O.V. Byrka et al. Repetitive plasma loads typical for ITER type-I ELMs: Simulation at QSPA Kh-50.PLASMA 2005. ed. By Sadowski M.J., AIP Conference Proceedings, American Institute of Physics, 2006, V 812, p. 128-135., J. Linke. Private communications.]. The reason for tungsten cracking under severe heat loads is thermo stress. It appears as due to temperature gradient in solid tungsten as in resolidified layer after cooling down. Both thermo stresses are of the same value, but the gradiental stress is compressive and the stress in the resolidified layer is tensile. The last one is most dangerous for crack formation and it was investigated in this work. The thermo stress in tungsten that develops during cooling from the melting temperature down to room temperature is ∼ 8-16 GPa. Tensile strength of tungsten is much lower, < 1 GPa at room temperature, and at high temperatures it drops at least for one order of magnitude. As a consequence, various cracks of different characteristic scales appear at the heated surface of the resolidified layer. For simulation of the cracks in tungsten the numeric code PEGASUS-3D [Pestchanyi and I. Landman. Improvement of the CFC structure to

  9. Autonomous Cryogenics Loading Operations Simulation Software: Knowledgebase Autonomous Test Engineer

    Science.gov (United States)

    Wehner, Walter S., Jr.

    2013-01-01

    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).

  10. LMFBR subassembly response to simulated local pressure loadings

    International Nuclear Information System (INIS)

    Marciniak, T.J.; Ash, J.E.; Marchertas, A.H.; Cagliostro, D.J.

    1976-01-01

    The structural response of liquid metal fast breeder reactor (LMFBR) subassemblies to local accidental events is of interest in assessing the safety of such systems. Problems to be resolved include failure propagation modes from pin to pin and from subassembly to subassembly. Factors which must be considered include: (a) the geometry of the structure, (b) uncertainty of the pressure-energy source, (c) uncertainty of materials properties under reactor operating conditions, and (d) the difficulty in performing in-pile or out-of-pile experiments which would simulate the above conditions. The main effort in evaluating the subassembly response has been centered around the development of appropriate analyses based on the finite element technique. Analysis has been extended to include not only the subassembly duct structure itself, but also the fluid environment, both within subassemblies and between them. These models and codes have been devised to cover a wide range of accident loading conditions, and can treat various materials as their properties become known. The effort described here is centered mainly around an experimental effort aimed at verfying, modifying or extending the models used in treating subassembly damage propagation. To verify the finite element codes under development, a series of out-of-pile room temperature experiments has been performed on LMFBR-type subassembly ducts under various loading conditions. (Auth.)

  11. Effect of ventilation rate and board loading on formaldehyde concentration : a critical review of the literature

    Science.gov (United States)

    George E. Myers

    1984-01-01

    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....

  12. Estimation of critical loads for radiocaesium in Fennoscandia and Northwest Russia

    International Nuclear Information System (INIS)

    Howard, B.J.; Wright, S.M.; Barnett, C.L.; Skuterud, L.; Strand, P.

    2002-01-01

    The application of the critical loads methodology for radioactive contamination of Arctic and sub-arctic ecosystems, where natural and semi-natural food products are important components of the diet of many people, is proposed and discussed. The critical load is herein defined as the amount of radionuclide deposition necessary to produce radionuclide activity concentrations in food products exceeding intervention limits. The high transfer of radiocaesium to reindeer meat gives this product the lowest critical load, even though the intervention limit is relatively high compared with other products. Ecological half-lives of radiocaesium in natural and semi-natural products are often very long, and it is therefore important to take account of contamination already present in the event of an accident affecting areas where such products are important. In particular, the long ecological half-life for radiocaesium in moose meat means that the critical load is highly sensitive to prior deposition. An example of the potential application of the method for emergency preparedness is given for the Chernobyl accident

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

    Energy Technology Data Exchange (ETDEWEB)

    Floeysand, I; Loebersli, E [eds.

    1996-01-01

    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.

  14. 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

    2004-01-01

    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 loads) voor cadmium en lood in

  15. Updated assessment of critical loads of lead and cadmium for European forest soils

    NARCIS (Netherlands)

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

    2002-01-01

    At its 20th session the Working Group on Effects (WGE) of the Convention on Long-range Transboundary Air Pollution of the United Nations Economic Commission for Europe (UNECECLRTAP), noted the need to further develop and test the methodology for mapping critical loads for cadmium and lead. To this

  16. Lichen-based critical loads for atmospheric nitrogen deposition in Western Oregon and Washington forests, USA

    Science.gov (United States)

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

    2010-01-01

    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,...

  17. Application of static critical load models for acidity to high mountain lakes in Europe

    Czech Academy of Sciences Publication Activity Database

    Curtis, C. J.; Barbieri, A.; Camarero, L.; Gabathuler, M.; Galas, J.; Hanselmann, K.; Kopáček, Jiří; Mosello, R.; Nickus, U.; Rose, N.; Stuchlík, E.; Thies, H.; Ventura, M.; Wright, R.

    2002-01-01

    Roč. 2, č. 2 (2002), s. 115-126 ISSN 1567-7230 Grant - others:EU(XE) MOLAR ENV4-CT95-0007; EU(XE) Environment and Climate Programme Keywords : acid deposition * critical loads Subject RIV: DJ - Water Pollution ; Quality

  18. 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)

    1996-09-01

    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)

  19. Effects of nitrogen deposition and empirical nitrogen critical loads for ecoregions of the United States

    Science.gov (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.

    2011-01-01

    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

  20. Determination of the critical micelle concentration in simulations of surfactant systems.

    Science.gov (United States)

    Santos, Andrew P; Panagiotopoulos, Athanassios Z

    2016-01-28

    Alternative methods for determining the critical micelle concentration (cmc) are investigated using canonical and grand canonical Monte Carlo simulations of a lattice surfactant model. A common measure of the cmc is the "free" (unassociated) surfactant concentration in the presence of micellar aggregates. Many prior simulations of micellizing systems have observed a decrease in the free surfactant concentration with overall surfactant loading for both ionic and nonionic surfactants, contrary to theoretical expectations from mass-action models of aggregation. In the present study, we investigate a simple lattice nonionic surfactant model in implicit solvent, for which highly reproducible simulations are possible in both the canonical (NVT) and grand canonical (μVT) ensembles. We confirm the previously observed decrease of free surfactant concentration at higher overall loadings and propose an algorithm for the precise calculation of the excluded volume and effective concentration of unassociated surfactant molecules in the accessible volume of the solution. We find that the cmc can be obtained by correcting the free surfactant concentration for volume exclusion effects resulting from the presence of micellar aggregates. We also develop an improved method for determination of the cmc based on the maximum in curvature for the osmotic pressure curve determined from μVT simulations. Excellent agreement in cmc and other micellar properties between NVT and μVT simulations of different system sizes is observed. The methodological developments in this work are broadly applicable to simulations of aggregating systems using any type of surfactant model (atomistic/coarse grained) or solvent description (explicit/implicit).

  1. Simulated and Virtual Science Laboratory Experiments: Improving Critical Thinking and Higher-Order Learning Skills

    Science.gov (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.

  2. Mapping critical loads of nitrogen deposition for aquatic ecosystems in the Rocky Mountains, USA

    International Nuclear Information System (INIS)

    Nanus, Leora; Clow, David W.; Saros, Jasmine E.; Stephens, Verlin C.; Campbell, Donald H.

    2012-01-01

    Spatially explicit estimates of critical loads of nitrogen (N) deposition (CL Ndep ) for nutrient enrichment in aquatic ecosystems were developed for the Rocky Mountains, USA, using a geostatistical approach. The lowest CL Ndep estimates ( −1 yr −1 ) occurred in high-elevation basins with steep slopes, sparse vegetation, and abundance of exposed bedrock and talus. These areas often correspond with areas of high N deposition (>3 kg N ha −1 yr −1 ), resulting in CL Ndep exceedances ≥1.5 ± 1 kg N ha −1 yr −1 . CL Ndep and CL Ndep exceedances exhibit substantial spatial variability related to basin characteristics and are highly sensitive to the NO 3 − threshold at which ecological effects are thought to occur. Based on an NO 3 − threshold of 0.5 μmol L −1 , N deposition exceeds CL Ndep in 21 ± 8% of the study area; thus, broad areas of the Rocky Mountains may be impacted by excess N deposition, with greatest impacts at high elevations. - Highlights: ► Critical loads maps for nutrient enrichment effects of nitrogen deposition. ► Critical load estimates show spatial variability related to basin characteristics. ► Critical loads are sensitive to the nitrate threshold value for ecological effects. ► Broad areas of the Rocky Mountains may be impacted by excess nitrogen deposition. - Critical loads maps for nutrient enrichment effects of nitrogen deposition show that broad areas of the Rocky Mountains may be impacted by excess nitrogen deposition.

  3. The impact of occupational load carriage on carrier mobility: a critical review of the literature.

    Science.gov (United States)

    Carlton, Simon D; Orr, Robin M

    2014-01-01

    Military personnel and firefighters are required to carry occupational loads and complete tasks in hostile and unpredictable environments where a lack of mobility may risk lives. This review critically examines the literature investigating the impacts of load carriage on the mobility of these specialist personnel. Several literature databases, reference lists, and subject matter experts were employed to identify relevant studies. Studies meeting the inclusion criteria were critiqued using the Downs and Black protocol. Inter-rater agreement was determined by Cohen's κ. Twelve original research studies, which included male and female participants from military and firefighting occupations, were critiqued (κ = .81). A review of these papers found that as the carried load weight increased, carrier mobility during aerobic tasks (like road marching) and anaerobic tasks (like obstacle course negotiation) decreased. As such, it can be concluded that the load carried by some specialist personnel may increase their occupational risk by reducing their mobility.

  4. 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

    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...... 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...

  5. Load/resource matching for period-of-record computer simulation

    International Nuclear Information System (INIS)

    Lindsey, E.D. Jr.; Robbins, G.E. III

    1991-01-01

    The Southwestern Power Administration (Southwestern), an agency of the Department of Energy, is responsible for marketing the power and energy produced at Federal hydroelectric power projects developed by the U.S. Army Corps of Engineers in the southwestern United States. This paper reports that in order to maximize benefits from limited resources, to evaluate proposed changes in the operation of existing projects, and to determine the feasibility and marketability of proposed new projects, Southwestern utilizes a period-of-record computer simulation model created in the 1960's. Southwestern is constructing a new computer simulation model to take advantage of changes in computers, policy, and procedures. Within all hydroelectric power reservoir systems, the ability of the resources to match the load demand is critical and presents complex problems. Therefore, the method used to compare available energy resources to energy load demands is a very important aspect of the new model. Southwestern has developed an innovative method which compares a resource duration curve with a load duration curve, adjusting the resource duration curve to make the most efficient use of the available resources

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

    International Nuclear Information System (INIS)

    McNulty, Steven G.; Boggs, Johnny L.

    2010-01-01

    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

    Science.gov (United States)

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

    2017-08-01

    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. Phase-field model simulation of ferroelectric/antiferroelectric materials microstructure evolution under multiphysics loading

    Science.gov (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

  9. Critical current degradation in superconducting niobium-titanium alloys in external magnetic fields under loading

    International Nuclear Information System (INIS)

    Bojko, V.S.; Lazareva, M.B.; Starodubov, Ya.D.; Chernyj, O.V.; Gorbatenko, V.M.

    1992-01-01

    The effect of external magnetic fields on the stress at which the critical current starts to degrade (the degradation threshold σ 0 e ) under mechanical loads in superconducting Nb-Ti alloys is studied and a possible mechanism of realization of the effect observed is proposed.It is assumed that additional stresses on the transformation dislocation from the external magnetic fields are beneficial for the growth of martensite inclusions whose superconducting parameters (critical current density j k and critical temperature T k ) are lower then those in the initial material.The degradation threshold is studied experimentally in external magnetic fields H up to 7 T.The linear dependence σ 0 e (H) is observed.It is shown that external magnetic fields play an important role in the critical current degradation at the starting stages of deformation.This fact supports the assumption that the degradation of superconducting parameters under loading are due to the phenomenon of superelasticity,i.e. a reversible load-induced change in the martensite inclusions sizes rather than the reversible mechanical twinning.The results obtained are thought to be important to estimating superconducting solenoid stability in a wide range of magnetic fields

  10. Limitations of subjective cognitive load measures in simulation-based procedural training.

    Science.gov (United States)

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

    2015-08-01

    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

  11. Performance of a cognitive load inventory during simulated handoffs: Evidence for validity.

    Science.gov (United States)

    Young, John Q; Boscardin, Christy K; van Dijk, Savannah M; Abdullah, Ruqayyah; Irby, David M; Sewell, Justin L; Ten Cate, Olle; O'Sullivan, Patricia S

    2016-01-01

    Advancing patient safety during handoffs remains a public health priority. The application of cognitive load theory offers promise, but is currently limited by the inability to measure cognitive load types. To develop and collect validity evidence for a revised self-report inventory that measures cognitive load types during a handoff. Based on prior published work, input from experts in cognitive load theory and handoffs, and a think-aloud exercise with residents, a revised Cognitive Load Inventory for Handoffs was developed. The Cognitive Load Inventory for Handoffs has items for intrinsic, extraneous, and germane load. Students who were second- and sixth-year students recruited from a Dutch medical school participated in four simulated handoffs (two simple and two complex cases). At the end of each handoff, study participants completed the Cognitive Load Inventory for Handoffs, Paas' Cognitive Load Scale, and one global rating item for intrinsic load, extraneous load, and germane load, respectively. Factor and correlational analyses were performed to collect evidence for validity. Confirmatory factor analysis yielded a single factor that combined intrinsic and germane loads. The extraneous load items performed poorly and were removed from the model. The score from the combined intrinsic and germane load items associated, as predicted by cognitive load theory, with a commonly used measure of overall cognitive load (Pearson's r = 0.83, p load during handoffs may be measured via a self-report measure. Additional work is required to develop an adequate measure of extraneous load.

  12. Action simulation plays a critical role in deceptive action recognition.

    Science.gov (United States)

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

    2013-01-09

    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 the ability to recognize deceptive body movements. We recorded motor-evoked potentials during a faked-action discrimination (FAD) task: participants watched videos of actors lifting a cube and judged whether the actors were trying to deceive them concerning the real weight of the cube. Seeing faked actions facilitated the observers' motor system more than truthful actions in a body-part-specific manner, suggesting that motor resonance was sensitive to deceptive movements. Furthermore, we found that TMS virtual lesion to the anterior node of the action observation network, namely the left inferior frontal cortex (IFC), reduced perceptual sensitivity in the FAD task. In contrast, no change in FAD task performance was found after virtual lesions to the left temporoparietal junction (control site). Moreover, virtual lesion to the IFC failed to affect performance in a difficulty-matched spatial-control task that did not require processing of spatiotemporal (acceleration) and configurational (limb displacement) features of seen actions, which are critical to detecting deceptive intent in the actions of others. These findings indicate that the human IFC is critical for recognizing deceptive body movements and suggest that FAD relies on the simulation of subtle changes in action kinematics within the motor system.

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

    International Nuclear Information System (INIS)

    Virotta, Francesco

    2012-01-01

    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 τ exp (a)∝a -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)τ 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 f =2 simulations using the Kaon decay constant f 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.

  14. A novel reformulation of the Theory of Critical Distances to design notched metals against dynamic loading

    International Nuclear Information System (INIS)

    Yin, T.; Tyas, A.; Plekhov, O.; Terekhina, A.; Susmel, L.

    2015-01-01

    Highlights: • The proposed method is successful in estimating dynamic strength of metals. • The critical distance varies as the loading/strain/displacement rate increases. • The reference strength varies as the loading/strain/displacement rate increases. • This method is recommended to be used with safety factors larger than 1.25. - Abstract: In the present study the linear-elastic Theory of Critical Distances (TCD) is reformulated to make it suitable for predicting the strength of notched metallic materials subjected to dynamic loading. The accuracy and reliability of the proposed reformulation of the TCD was checked against a number of experimental results generated by testing, under different loading/strain rates, notched cylindrical samples of aluminium alloy 6063-T5, titanium alloy Ti–6Al–4V, aluminium alloy AlMg6, and an AlMn alloy. To further validate the proposed design method also different data sets taken from the literature were considered. Such an extensive validation exercise allowed us to prove that the proposed reformulation of the TCD is successful in predicting the dynamic strength of notched metallic materials, this approach proving to be capable of estimates falling within an error interval of ±20%. Such a high level of accuracy is certainly remarkable, especially in light of the fact that it was reached without the need for explicitly modelling the stress vs. strain dynamic behaviour of the investigated ductile metals

  15. Vegetation community change points suggest that critical loads of nutrient nitrogen may be too high

    Science.gov (United States)

    Wilkins, Kayla; Aherne, Julian; Bleasdale, Andy

    2016-12-01

    It is widely accepted that elevated nitrogen deposition can have detrimental effects on semi-natural ecosystems, including changes to plant diversity. Empirical critical loads of nutrient nitrogen have been recommended to protect many sensitive European habitats from significant harmful effects. In this study, we used Threshold Indicator Taxa Analysis (TITAN) to investigate shifts in vegetation communities along an atmospheric nitrogen deposition gradient for twenty-two semi-natural habitat types (as described under Annex I of the European Union Habitats Directive) in Ireland. Significant changes in vegetation community, i.e., change points, were determined for twelve habitats, with seven habitats showing a decrease in the number of positive indicator species. Community-level change points indicated a decrease in species abundance along a nitrogen deposition gradient ranging from 3.9 to 15.3 kg N ha-1 yr-1, which were significantly lower than recommended critical loads (Wilcoxon signed-rank test; V = 6, p < 0.05). These results suggest that lower critical loads of empirical nutrient nitrogen deposition may be required to protect many European habitats. Changes to vegetation communities may mean a loss of sensitive indicator species and potentially rare species in these habitats, highlighting how emission reductions policies set under the National Emissions Ceilings Directive may be directly linked to meeting the goal set out under the European Union's Biodiversity Strategy of "halting the loss of biodiversity" across Europe by 2020.

  16. Effects and empirical critical loads of Nitrogen for ecoregions of the United States

    Science.gov (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.

    2015-01-01

    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.

  17. 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)

    2017-01-24

    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.

  18. Small-scale multi-axial hybrid simulation of a shear-critical reinforced concrete frame

    Science.gov (United States)

    Sadeghian, Vahid; Kwon, Oh-Sung; Vecchio, Frank

    2017-10-01

    This study presents a numerical multi-scale simulation framework which is extended to accommodate hybrid simulation (numerical-experimental integration). The framework is enhanced with a standardized data exchange format and connected to a generalized controller interface program which facilitates communication with various types of laboratory equipment and testing configurations. A small-scale experimental program was conducted using a six degree-of-freedom hydraulic testing equipment to verify the proposed framework and provide additional data for small-scale testing of shearcritical reinforced concrete structures. The specimens were tested in a multi-axial hybrid simulation manner under a reversed cyclic loading condition simulating earthquake forces. The physical models were 1/3.23-scale representations of a beam and two columns. A mixed-type modelling technique was employed to analyze the remainder of the structures. The hybrid simulation results were compared against those obtained from a large-scale test and finite element analyses. The study found that if precautions are taken in preparing model materials and if the shear-related mechanisms are accurately considered in the numerical model, small-scale hybrid simulations can adequately simulate the behaviour of shear-critical structures. Although the findings of the study are promising, to draw general conclusions additional test data are required.

  19. Surface water acidification and critical loads: exploring the F-factor

    Directory of Open Access Journals (Sweden)

    K. Bishop

    2009-11-01

    Full Text Available As acid deposition decreases, uncertainties in methods for calculating critical loads become more important when judgements have to be made about whether or not further emission reductions are needed. An important aspect of one type of model that has been used to calculate surface water critical loads is the empirical F-factor which estimates the degree to which acid deposition is neutralised before it reaches a lake at any particular point in time relative to the pre-industrial, steady-state water chemistry conditions.

    In this paper we will examine how well the empirical F-functions are able to estimate pre-industrial lake chemistry as lake chemistry changes during different phases of acidification and recovery. To accomplish this, we use the dynamic, process-oriented biogeochemical model SAFE to generate a plausible time series of annual runoff chemistry for ca. 140 Swedish catchments between 1800 and 2100. These annual hydrochemistry data are then used to generate empirical F-factors that are compared to the "actual" F-factor seen in the SAFE data for each lake and year in the time series. The dynamics of the F-factor as catchments acidify, and then recover are not widely recognised.

    Our results suggest that the F-factor approach worked best during the acidification phase when soil processes buffer incoming acidity. However, the empirical functions for estimating F from contemporary lake chemistry are not well suited to the recovery phase when the F-factor turns negative due to recovery processes in the soil. This happens when acid deposition has depleted the soil store of BC, and then acid deposition declines, reducing the leaching of base cations to levels below those in the pre-industrial era. An estimate of critical load from water chemistry during recovery and empirical F functions would therefore result in critical loads that are too low. Therefore, the empirical estimates of the F-factor are a significant source of

  20. 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

    2004-01-01

    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

  1. Theoretical assessment of a proposal for the simplified determination of critical loads of elastic shells

    International Nuclear Information System (INIS)

    Malmberg, T.

    1986-08-01

    Within the context of the stability analysis of the cryostat of a fusion reactor the question was raised whether or not the rather lengthy conventional stability analysis can be circumvented by applying a simplified strategy based on common linear Finite Element computer programs. This strategy involves the static linear deformation analysis of the structure with and without imperfections. For some simple stability problems this approach has been shown to be successful. The purpose of this study is to derive a general proof of the validity of this approach for thin shells with arbitrary geometry under hydrostatic pressure or dead loading along the boundary. This general assessment involves two types of analyses: 1) A general stability analysis for thin shells; this is based on a simple nonlinear shell theory and a stability criterion in form of the neutral (indifferent) equilibrium condition. This result is taken as reference solution. 2) A general linear deformation analysis for thin imperfect shells and the definition of a suitable scalar parameter (β-parameter) which should represent the reciprocal of the critical load factor. It is shown that the simplified strategy (=β-parameter approach'') generally is not capable to predict the actual critical load factor irrespective whether there is a hydrostatic pressure loading or dead loading along the edge of the shell. This general result is in contrast to the observations made for some simple stability problems. Nevertheless, the results of this study do not exclude the possibility that the simplified strategy will give reasonable approximate solutions at least for a restricted class of stability problems. (orig./HP) [de

  2. Si-coated single-walled carbon nanotubes under axial loads: An atomistic simulation study

    International Nuclear Information System (INIS)

    Song Haiyang; Zha Xinwei

    2007-01-01

    The mechanical properties of the Si-coated imperfect (5, 5) single-walled carbon nanotube (SWCNT), the imperfect (5, 5) SWCNT and several perfect armchair SWCNTs under axial loads were investigated using molecular dynamics simulation. The interactions between atoms were modeled using the empirical Tersoff potential and the Tersoff-Brenner potential coupled with the Lennard-Jones potential. We get Young's modulus of the defective (5, 5) nanotube with and without the Si coating under axial tension 1107.92 and 1076.02 GPa, respectively. The results also show that the structure failure of the Si-coated imperfect (5, 5) SWCNT under axial compression occurs at a slightly higher strain than for the perfect (5, 5) SWCNT. Therefore, we can confirm the protective effect of Si as a coating material for defective SWCNTs. We also obtain the critical buckling strains of perfect SWCNTs

  3. Review on modeling and simulation of interdependent critical infrastructure systems

    International Nuclear Information System (INIS)

    Ouyang, Min

    2014-01-01

    Modern societies are becoming increasingly dependent on critical infrastructure systems (CISs) to provide essential services that support economic prosperity, governance, and quality of life. These systems are not alone but interdependent at multiple levels to enhance their overall performance. However, recent worldwide events such as the 9/11 terrorist attack, Gulf Coast hurricanes, the Chile and Japanese earthquakes, and even heat waves have highlighted that interdependencies among CISs increase the potential for cascading failures and amplify the impact of both large and small scale initial failures into events of catastrophic proportions. To better understand CISs to support planning, maintenance and emergency decision making, modeling and simulation of interdependencies across CISs has recently become a key field of study. This paper reviews the studies in the field and broadly groups the existing modeling and simulation approaches into six types: empirical approaches, agent based approaches, system dynamics based approaches, economic theory based approaches, network based approaches, and others. Different studies for each type of the approaches are categorized and reviewed in terms of fundamental principles, such as research focus, modeling rationale, and the analysis method, while different types of approaches are further compared according to several criteria, such as the notion of resilience. Finally, this paper offers future research directions and identifies critical challenges in the field. - Highlights: • Modeling approaches on interdependent critical infrastructure systems are reviewed. • I mainly review empirical, agent-based, system-dynamics, economic, network approaches. • Studies by each approach are sorted out in terms of fundamental principles. • Different approaches are further compared with resilience as the main criterion

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

    Energy Technology Data Exchange (ETDEWEB)

    Virotta, Francesco

    2012-02-21

    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.

  5. Determination of the critical micelle concentration in simulations of surfactant systems

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Andrew P.; Panagiotopoulos, Athanassios Z., E-mail: azp@princeton.edu [Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544 (United States)

    2016-01-28

    Alternative methods for determining the critical micelle concentration (cmc) are investigated using canonical and grand canonical Monte Carlo simulations of a lattice surfactant model. A common measure of the cmc is the “free” (unassociated) surfactant concentration in the presence of micellar aggregates. Many prior simulations of micellizing systems have observed a decrease in the free surfactant concentration with overall surfactant loading for both ionic and nonionic surfactants, contrary to theoretical expectations from mass-action models of aggregation. In the present study, we investigate a simple lattice nonionic surfactant model in implicit solvent, for which highly reproducible simulations are possible in both the canonical (NVT) and grand canonical (μVT) ensembles. We confirm the previously observed decrease of free surfactant concentration at higher overall loadings and propose an algorithm for the precise calculation of the excluded volume and effective concentration of unassociated surfactant molecules in the accessible volume of the solution. We find that the cmc can be obtained by correcting the free surfactant concentration for volume exclusion effects resulting from the presence of micellar aggregates. We also develop an improved method for determination of the cmc based on the maximum in curvature for the osmotic pressure curve determined from μVT simulations. Excellent agreement in cmc and other micellar properties between NVT and μVT simulations of different system sizes is observed. The methodological developments in this work are broadly applicable to simulations of aggregating systems using any type of surfactant model (atomistic/coarse grained) or solvent description (explicit/implicit)

  6. Determination of the critical micelle concentration in simulations of surfactant systems

    International Nuclear Information System (INIS)

    Santos, Andrew P.; Panagiotopoulos, Athanassios Z.

    2016-01-01

    Alternative methods for determining the critical micelle concentration (cmc) are investigated using canonical and grand canonical Monte Carlo simulations of a lattice surfactant model. A common measure of the cmc is the “free” (unassociated) surfactant concentration in the presence of micellar aggregates. Many prior simulations of micellizing systems have observed a decrease in the free surfactant concentration with overall surfactant loading for both ionic and nonionic surfactants, contrary to theoretical expectations from mass-action models of aggregation. In the present study, we investigate a simple lattice nonionic surfactant model in implicit solvent, for which highly reproducible simulations are possible in both the canonical (NVT) and grand canonical (μVT) ensembles. We confirm the previously observed decrease of free surfactant concentration at higher overall loadings and propose an algorithm for the precise calculation of the excluded volume and effective concentration of unassociated surfactant molecules in the accessible volume of the solution. We find that the cmc can be obtained by correcting the free surfactant concentration for volume exclusion effects resulting from the presence of micellar aggregates. We also develop an improved method for determination of the cmc based on the maximum in curvature for the osmotic pressure curve determined from μVT simulations. Excellent agreement in cmc and other micellar properties between NVT and μVT simulations of different system sizes is observed. The methodological developments in this work are broadly applicable to simulations of aggregating systems using any type of surfactant model (atomistic/coarse grained) or solvent description (explicit/implicit)

  7. Fast assessment of the critical principal stress direction for multiple separated multiaxial loadings

    Directory of Open Access Journals (Sweden)

    M. Cova

    2015-07-01

    Full Text Available The critical plane calculation for multiaxial damage assessment is often a demanding task, particularly for large FEM models of real components. Anyway, in actual engineering requests, sometime, it is possible to take advantage of the specific properties of the investigated case. This paper deals with the problem of a mechanical component loaded by multiple, but “time-separated”, multiaxial external loads. The specific material damage is dependent from the max principal stress variation with a significant mean stress sensitivity too. A specifically fitted procedure was developed for a fast computation, at each node of a large FEM model, of the direction undergoing the maximum fatigue damage; the procedure is defined according to an effective stress definition based on the max principal stress amplitude and mean value. The procedure is presented in a general form, applicable to the similar cases.

  8. Evaluation of nuclear characteristics of minor actinide loaded core. Analyses of BFS-69 and BFS-66-2 critical experiments

    International Nuclear Information System (INIS)

    Hazama, Taira; Sato, Wakaei

    2010-09-01

    Collaboration with Russian Institute of Physics and Power Engineering named 'Investigation of neutronic-physical characteristics and their change when introducing large quantity of neptunium (Np) at different BFS critical assemblies' has been accomplished. This is the second report of the collaboration to describe experimental information and analysis results on BFS-69 and BFS-66-2 critical experiments. In the experiments, various nuclear characteristics were measured in 2 kinds of cores with/without Np loading of about 8 kg. JAEA's standard analysis results were presented with four kinds of nuclear data (JENDL-3.2, JENDL-3.3, JENDL/AC-2008, and ENDF/BVII). Analytical results show: 1) An overestimation trend has been observed in BFS-69 criticality results, especially with JENDL-3.3 and JENDL/AC-2008. The difference from ENDF/B-II having better results mainly lies in the average cosine of the scattering angle around 1 MeV. 2) A small discrepancy exists in BFS-69 Na void reactivity results with the three JENDL nuclear data. The difference from ENDF/B-II mainly lies in scattering cross sections of sodium around 1 MeV and fission cross section of 239 Pu around 1 keV. 3) The analysis results simulate measured Np effects on nuclear characteristics within experimental errors. (author)

  9. On Input Vector Representation for the SVR model of Reactor Core Loading Pattern Critical Parameters

    International Nuclear Information System (INIS)

    Trontl, K.; Pevec, D.; Smuc, T.

    2008-01-01

    Determination and optimization of reactor core loading pattern is an important factor in nuclear power plant operation. The goal is to minimize the amount of enriched uranium (fresh fuel) and burnable absorbers placed in the core, while maintaining nuclear power plant operational and safety characteristics. The usual approach to loading pattern optimization involves high degree of engineering judgment, a set of heuristic rules, an optimization algorithm and a computer code used for evaluating proposed loading patterns. The speed of the optimization process is highly dependent on the computer code used for the evaluation. Recently, we proposed a new method for fast loading pattern evaluation based on general robust regression model relying on the state of the art research in the field of machine learning. We employed Support Vector Regression (SVR) technique. SVR is a supervised learning method in which model parameters are automatically determined by solving a quadratic optimization problem. The preliminary tests revealed a good potential of the SVR method application for fast and accurate reactor core loading pattern evaluation. However, some aspects of model development are still unresolved. The main objective of the work reported in this paper was to conduct additional tests and analyses required for full clarification of the SVR applicability for loading pattern evaluation. We focused our attention on the parameters defining input vector, primarily its structure and complexity, and parameters defining kernel functions. All the tests were conducted on the NPP Krsko reactor core, using MCRAC code for the calculation of reactor core loading pattern critical parameters. The tested input vector structures did not influence the accuracy of the models suggesting that the initially tested input vector, consisted of the number of IFBAs and the k-inf at the beginning of the cycle, is adequate. The influence of kernel function specific parameters (σ for RBF kernel

  10. Initial particle loadings for a nonuniform simulation plasma in a magnetic field

    International Nuclear Information System (INIS)

    Naitou, Hiroshi; Kamimura, Tetsuo; Tokuda, Sinji.

    1978-09-01

    Improved methods for initially loading particles in a magnetized simulation plasma with nonuniform density and temperature distributions are proposed. In the usual guiding center loading (GCL), a charge separation coming from finite Larmor radius effects remains due to the difference between the guiding center density and the actual density. The modified guiding center loading (MGCL) presented here eliminates the electric field so generated and can be used for arbitrary density and temperature profiles. Some applications of these methods to actual simulations are given for comparison. The significance of these methods of initial particle loadings is also discussed. (author)

  11. Optimizing Cognitive Load for Learning from Computer-Based Science Simulations

    Science.gov (United States)

    Lee, Hyunjeong; Plass, Jan L.; Homer, Bruce D.

    2006-01-01

    How can cognitive load in visual displays of computer simulations be optimized? Middle-school chemistry students (N = 257) learned with a simulation of the ideal gas law. Visual complexity was manipulated by separating the display of the simulations in two screens (low complexity) or presenting all information on one screen (high complexity). The…

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

    Directory of Open Access Journals (Sweden)

    E. E. Bridcut

    2004-01-01

    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

  13. Asymmetric fluid criticality. II. Finite-size scaling for simulations.

    Science.gov (United States)

    Kim, Young C; Fisher, Michael E

    2003-10-01

    The vapor-liquid critical behavior of intrinsically asymmetric fluids is studied in finite systems of linear dimensions L focusing on periodic boundary conditions, as appropriate for simulations. The recently propounded "complete" thermodynamic (L--> infinity) scaling theory incorporating pressure mixing in the scaling fields as well as corrections to scaling [Phys. Rev. E 67, 061506 (2003)] is extended to finite L, initially in a grand canonical representation. The theory allows for a Yang-Yang anomaly in which, when L--> infinity, the second temperature derivative (d2musigma/dT2) of the chemical potential along the phase boundary musigmaT diverges when T-->Tc-. The finite-size behavior of various special critical loci in the temperature-density or (T,rho) plane, in particular, the k-inflection susceptibility loci and the Q-maximal loci--derived from QL(T,L) is identical with 2L/L where m is identical with rho-L--is carefully elucidated and shown to be of value in estimating Tc and rhoc. Concrete illustrations are presented for the hard-core square-well fluid and for the restricted primitive model electrolyte including an estimate of the correlation exponent nu that confirms Ising-type character. The treatment is extended to the canonical representation where further complications appear.

  14. Numerical simulation of wind loads on solar panels

    Science.gov (United States)

    Su, Kao-Chun; Chung, Kung-Ming; Hsu, Shu-Tsung

    2018-05-01

    Solar panels mounted on the roof of a building or ground are often vulnerable to strong wind loads. This study aims to investigate wind loads on solar panels using computational fluid dynamic (CFD). The results show good agreement with wind tunnel data, e.g. the streamwise distribution of mean surface pressure coefficient of a solar panel. Wind uplift for solar panels with four aspect ratios is evaluated. The effect of inclined angle and clearance (or height) of a solar panel is addressed. It is found that wind uplift of a solar panel increases when there is an increase in inclined angle and the clearance above ground shows an opposite effect.

  15. Simulating tokamak PFC performance using simultaneous dual beam particle loading with pulsed heat loading

    Science.gov (United States)

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

    2017-10-01

    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.

  16. 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)

    2014-10-01

    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.

  17. Lichen-based critical loads for atmospheric nitrogen deposition in Western Oregon and Washington Forests, USA

    Energy Technology Data Exchange (ETDEWEB)

    Geiser, Linda H., E-mail: lgeiser@fs.fed.u [US Forest Service Pacific Northwest Region Air Resource Management Program, Siuslaw National Forest, PO Box 1148, Corvallis, OR 97339 (United States); Jovan, Sarah E. [US Forest Service Forest Inventory and Analysis Program, Pacific Northwest Research Station, 620 SW Main St, Suite 400, Portland, OR 97205 (United States); Glavich, Doug A. [US Forest Service Pacific Northwest Region Air Resource Management Program, Siuslaw National Forest, PO Box 1148, Corvallis, OR 97339 (United States); Porter, Matthew K. [Laboratory for Atmospheric Research, Washington State University, Pullman, WA 99164 (United States)

    2010-07-15

    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{sup -1} y{sup -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. - Lichen-based critical loads for N deposition in western Oregon and Washington forests ranged from 3 to 9 kg ha{sup -1} y{sup -1}, increasing with mean annual precipitation.

  18. Two Coupled Queues with Vastly Different Arrival Rates: Critical Loading Case

    Directory of Open Access Journals (Sweden)

    Charles Knessl

    2011-01-01

    Full Text Available We consider two coupled queues with a generalized processor sharing service discipline. The second queue has a much smaller Poisson arrival rate than the first queue, while the customer service times are of comparable magnitude. The processor sharing server devotes most of its resources to the first queue, except when it is empty. The fraction of resources devoted to the second queue is small, of the same order as the ratio of the arrival rates. We assume that the primary queue is heavily loaded and that the secondary queue is critically loaded. If we let the small arrival rate to the secondary queue be O(ε, where 0≤ε≪1, then in this asymptotic limit the number of customers in the first queue will be large, of order O(ε-1, while that in the second queue will be somewhat smaller, of order O(ε-1/2. We obtain a two-dimensional diffusion approximation for this model and explicitly solve for the joint steady state probability distribution of the numbers of customers in the two queues. This work complements that in (Morrison, 2010, which the second queue was assumed to be heavily or lightly loaded, leading to mean queue lengths that were O(ε-1 or O(1, respectively.

  19. Simulation of a curved flume bed-load experiment

    NARCIS (Netherlands)

    Talmon, A.M.

    1988-01-01

    The mathematical model for river bend morphology, as developed by Olesen, for bed-load transport is discussed, by comparing the results with some new experimental data. The model consists of a two-dimensional depth-averaged flow model together with a sediment balance and can be used to compute the

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

    DEFF Research Database (Denmark)

    Keller, Thomas; Lamandé, Mathieu; Arvidsson, Johan

    The load transfer within agricultural soil is typically modelled on the basis of the theory of stress transmission in elastic media, usually in the semi-empirical form that includes the “concentration factor” (v). Measurements of stress in soil are needed to evaluate model calculations, but may...

  1. Benzo[a]pyrene in urban environments of eastern Moscow: pollution levels and critical loads

    Science.gov (United States)

    Kasimov, Nikolay S.; Kosheleva, Natalia E.; Nikiforova, Elena M.; Vlasov, Dmitry V.

    2017-02-01

    Polycyclic aromatic hydrocarbons (PAHs), particularly benzo[a]pyrene (BaP), are toxic compounds emitted from various anthropogenic sources. Understanding the BaP concentrations, dynamics and decomposition in soil is required to assess the critical loads of BaP in urban environments. This study is the first attempt to evaluate all major input and output components of benzo[a]pyrene (BaP) balance and to calculate the permissible load on the urban environment in different land-use zones in the Eastern district of Moscow. BaP contamination of the snow cover in the Eastern district of Moscow was related to daily BaP fallout from the atmosphere. In 2010, the mean content of the pollutant in the snow dust was 1942 ng g-1, whereas the average intensity of its fallout was 7.13 ng m-2 per day. Across the territory, BaP winter fallout intensities varied from 0.3 to 1100 ng m-2 per day. The average BaP content in the surface (0-10 cm) soil horizons was 409 ng g-1, which is 83 times higher than the local background value and 20 times higher than the maximum permissible concentration (MPC) accepted in Russia. The variations in soil and snow BaP concentrations among different land-use zones were examined. A significant contribution of BaP from the atmosphere to urban soils was identified. Based on the measurements of BaP atmospheric fallout and BaP reserves in the soils, the critical loads of BaP for the land-use zones in the Eastern district were calculated for different values of degradation intensity and different exposure times. It was established that at an annual degradation intensity of 1-10 %, ecologically safe BaP levels in the soils of all land-use zones, excluding the agricultural zone, will only be reached after many decades or centuries.

  2. Quality of computerized blast load simulation for non-linear dynamic ...

    African Journals Online (AJOL)

    Quality of computerized blast load simulation for non-linear dynamic response ... commercial software system and a special-purpose, blast-specific software product to ... depend both on the analysis model of choice and the stand-off distances.

  3. CFD simulations of wind loads on a container ship : Validation and impact of geometrical simplifactions

    NARCIS (Netherlands)

    Janssen, W.D.; Blocken, B.J.E.; van Wijhe, H.J.

    2017-01-01

    Due to the increasing windage area of container ships, wind loads are playing a more important role in navigating the ship at open sea and especially through harbor areas. This paper presents 3D steady RANS CFD simulations of wind loads on a container ship, validation with wind-tunnel measurements

  4. Influence of the heater material on the critical heat load at boiling of liquids on surfaces with different sizes

    Science.gov (United States)

    Anokhina, E. V.

    2010-05-01

    Data on critical heat loads q cr for the saturated and unsaturated pool boiling of water and ethanol under atmospheric pressure are reported. It is found experimentally that the critical heat load does not necessarily coincide with the heat load causing burnout of the heater, which should be taken into account. The absolute values of q cr for the boiling of water and ethanol on copper surfaces 65, 80, 100, 120, and 200 μm in diameter; tungsten surface 100 μm in diameter; and nichrome surface 100 μm in diameter are obtained experimentally.

  5. Simulation model of load balancing in distributed computing systems

    Science.gov (United States)

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

    2017-02-01

    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.

  6. Susceptibility of forests in the northeastern USA to nitrogen and sulfur deposition: critical load exceedance and forest health

    Science.gov (United States)

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

    2013-01-01

    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...

  7. Measuring cognitive load: mixed results from a handover simulation for medical students.

    Science.gov (United States)

    Young, John Q; Irby, David M; Barilla-LaBarca, Maria-Louise; Ten Cate, Olle; O'Sullivan, Patricia S

    2016-02-01

    The application of cognitive load theory to workplace-based activities such as patient handovers is hindered by the absence of a measure of the different load types. This exploratory study tests a method for measuring cognitive load during handovers. The authors developed the Cognitive Load Inventory for Handoffs (CLI4H) with items for intrinsic, extraneous, and germane load. Medical students completed the measure after participating in a simulated handover. Exploratory factor and correlation analyses were performed to collect evidence for validity. Results yielded a two-factor solution for intrinsic and germane load that explained 50 % of the variance. The extraneous load items performed poorly and were removed from the model. The score for intrinsic load correlated with the Paas Cognitive Load scale (r = 0.31, p = 0.004) and was lower for students with more prior handover training (p = 0.036). Intrinsic load did not, however, correlate with performance. Germane load did not correlate with the Paas Cognitive Load scale but did correlate as expected with performance (r = 0.30, p = 0.005) and was lower for those students with more prior handover training (p = 0.03). The CLI4H yielded mixed results with some evidence for validity of the score from the intrinsic load items. The extraneous load items performed poorly and the use of only a single item for germane load limits conclusions. The instrument requires further development and testing. Study results and limitations provide guidance to future efforts to measure cognitive load during workplace-based activities, such as handovers.

  8. Determination and Distribution of Critical Loads: Application to the Forest Soils in the Autonomous Region of Madrid

    International Nuclear Information System (INIS)

    Sousa, M.; Schmid, T.; Rabago, I.

    2000-01-01

    The critical loads of acidity and sulphur have been determined for forest soils within the north and northwest 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

  9. Simulating the Camp David Negotiations: A Problem-Solving Tool in Critical Pedagogy

    Science.gov (United States)

    McMahon, Sean F.; Miller, Chris

    2013-01-01

    This article reflects critically on simulations. Building on the authors' experience simulating the Palestinian-Israeli-American Camp David negotiations of 2000, they argue that simulations are useful pedagogical tools that encourage creative--but not critical--thinking and constructivist learning. However, they can also have the deleterious…

  10. Electric vehicles as flexible loads – A simulation approach using empirical mobility data

    International Nuclear Information System (INIS)

    Metz, Michael; Doetsch, Christian

    2012-01-01

    Due to the rapid increase of wind and photovoltaic generation, flexible storage applications become more important. Electric vehicles are supposed as one option to fill the gap between a fixed energy demand and a stochastic feed in from fluctuating energy sources. But the charging loads will also affect the grid load, since the transport sector contributes considerably to the total energy consumption today. This study examines the conflicting relationship between user mobility and grid support and introduces an approach to simulate large vehicle fleets on the basis of individual driving profiles. 9744 driving profiles from the German mobility panel were used within this examination. 958 were classified as potential early adopters for electric vehicles. Those vehicles could provide grid support in 81% of the time, when charging spots are available at home and at work. We simulated the charging loads under the restrictions of the individual mobility for the scenario 2030. Uncoordinated charging will increase the load fluctuations, whereas coordinated charging loads allow load shifting without limiting the mobility. The additional electricity demand is moderate over the next two decades. -- Highlights: ► We processed and analyzed 9744 driving profiles from a German mobility study. ► We simulated 3 concepts for a charging control, resulting in different load profiles. ► Additional energy demand of electric vehicles is moderate over the next two decades. ► Uncoordinated charging will increase the total peak load, coordinated charging can balance fluctuations.

  11. Air permeability for a concrete shear wall after a damaging seismic load simulation cycle

    International Nuclear Information System (INIS)

    Girrens, S.P.; Farrar, C.R.

    1991-01-01

    A study was initiated to estimate air leakage, driven by wind-generated pressure gradients, from a seismically damaged concrete structure. This paper describes an experiment performed to measure the air permeability in a reinforced concrete shear wall, both before and after simulated seismic loading. Static load-cycle testing was used to simulate earthquake loading. Permeability measurements were made by pressurizing one side of the shear wall above atmospheric conditions and recording the transient-pressure decay. Air permeability measurements made on the shear wall before loading fell within the range of values for concrete permeability published in the literature. As long as the structure exhibited linear load-displacement response, no variation in the air permeability was detected. However, experimental results indicate that the air permeability in the shear wall increased by a factor of 40 after the wall had been damaged (cracked)

  12. Comparison of coupled and uncoupled load simulations on a jacket support structure

    DEFF Research Database (Denmark)

    Haselbach, Philipp Ulrich; Natarajan, Anand; Jiwinangun, Randi Gusto

    2013-01-01

    In this article, a comparison of the moments and forces at the joints of a jacket structure is made between fully coupled aerohydroelastic simulations in HAWC2 and uncoupled load predictions in the finite element software Abaqus. The jacket sub structure is modelled in moderate deep waters of 50m...... structure similar to the Upwind reference jacket is developed in the Abaqus environment, to which is added the transition piece and tower. The aeroelastic loads determined in normal operating conditions of the turbine is integrated and centralized as nodal forces and moments acting at the tower top...... in Abaqus. The fully coupled simulation is implemented and performed in HAWC2. In the uncoupled case, the loads (wave loads and tower base loads) are analysed by an implicit structural Finite Element Analysis (Abaqus 6.11-1). A subroutine is used as a preprocessor generating a beam element model and linking...

  13. Numerical simulation of void growth under dynamic loading

    International Nuclear Information System (INIS)

    Iqbal, A.

    1996-01-01

    Following a brief general review of developments in material behavior under high strain rates, a cylindrical cell surrounding a spherical void in OFHC copper is numerically simulated by Zerri-Armstrong model. This simulation results show that the plastic deformation tends to be concentrated in the vicinity of voids either in the axial or transverse direction depending upon the stress state. This event is associated with the accelerated void through accompanying coalescence causing ductile fracture. A3-node triangular mesh generation code used as input for finite element code is developed by a 'Central Generation' technique. (author)

  14. Combining Ecosystem Service and Critical Load Concepts for Resource Management and Public Policy

    Directory of Open Access Journals (Sweden)

    Timothy J. Sullivan

    2012-11-01

    Full Text Available Land management and natural resource public policy decision-making in the United States can benefit from two resource damage/recovery concepts: ecosystem service (ES and critical load (CL. The purpose of this paper is to suggest an integrated approach to the application of ES and CL principles for public land management and natural resource policy decision-making. One well known example that is appropriate for ES and CL evaluation is examined here: the acidification of soil and drainage water by atmospheric deposition of acidifying sulfur and nitrogen compounds. A conceptual framework illustrates how the ES and CL approaches can be combined in a way that enhances the strengths of each. This framework will aid in the process of translating ES and CL principles into land management and natural resource policy decision-making by documenting the impacts of pollution on environmental goods and services that benefit humans.

  15. Mapping critical loads of nitrogen deposition for aquatic ecosystems in the Rocky Mountains, USA

    Science.gov (United States)

    Nanus, Leora; Clow, David W.; Saros, Jasmine E.; Stephens, Verlin C.; Campbell, Donald H.

    2012-01-01

    Spatially explicit estimates of critical loads of nitrogen (N) deposition (CLNdep) for nutrient enrichment in aquatic ecosystems were developed for the Rocky Mountains, USA, using a geostatistical approach. The lowest CLNdep estimates (-1 yr-1) occurred in high-elevation basins with steep slopes, sparse vegetation, and abundance of exposed bedrock and talus. These areas often correspond with areas of high N deposition (>3 kg N ha-1 yr-1), resulting in CLNdep exceedances ≥1.5 ± 1 kg N ha-1 yr-1. CLNdep and CLNdep exceedances exhibit substantial spatial variability related to basin characteristics and are highly sensitive to the NO3- threshold at which ecological effects are thought to occur. Based on an NO3- threshold of 0.5 μmol L-1, N deposition exceeds CLNdep in 21 ± 8% of the study area; thus, broad areas of the Rocky Mountains may be impacted by excess N deposition, with greatest impacts at high elevations.

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

    DEFF Research Database (Denmark)

    Dimitrov, Nikolay Krasimirov; Natarajan, Anand

    2017-01-01

    We demonstrate a method for incorporating wind velocity measurements from multiple-point scanning lidars into threedimensional wind turbulence time series serving as input to wind turbine load simulations. Simulated lidar scanning patterns are implemented by imposing constraints on randomly gener...

  17. The Effect of Computer Simulations on Acquisition of Knowledge and Cognitive Load: A Gender Perspective

    Science.gov (United States)

    Kaheru, Sam J.; Kriek, Jeanne

    2016-01-01

    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…

  18. Study on the Flare Load Estimation of the Deethanizer using Dynamic Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Park, Kyungtae; Won, Wangyun [GS EC, Seoul (Korea, Republic of); Shin, Dongil [Myongji University, Yongin (Korea, Republic of)

    2014-10-15

    A flare system is a very important system that crucially affects on the process safety in chemical plants. If a flare system is designed too small, it cannot prevent catastrophic accidents of a chemical plant. On the other hand, if a flare system is designed too large, it will waste resources. Therefore, reasonable relief load estimation has been a crucial issue in the industry. American Petroleum Institute (API) suggests basic guidelines for relief load estimation, and a lot of engineering companies have developed their own relief load estimation methods that use an unbalanced heat and material method. However, these methods have to involve lots of conservative assumptions that lead to an overestimation of relief loads. In this study, the new design procedure for a flare system based on dynamic simulation was proposed in order to avoid the overestimation of relief loads. The relief load of a deethanizer process was tested to verify the performance of the proposed design procedure.

  19. 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)

    2008-09-15

    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.

  20. Hydrodynamic simulations of microjetting from shock-loaded grooves

    Science.gov (United States)

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

    2017-01-01

    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.

  1. Blast Load Simulator Experiments for Computational Model Validation: Report 2

    Science.gov (United States)

    2017-02-01

    simulations of these explosive events and their effects . These codes are continuously improving, but still require validation against experimental data to...contents of this report are not to be used for advertising , publication, or promotional purposes. Citation of trade names does not constitute an...12 Figure 18. Ninety-five percent confidence intervals on measured peak pressure. ............................ 14 Figure 19. Ninety-five percent

  2. Coarse-grained simulation of a real-time process control network under peak load

    International Nuclear Information System (INIS)

    George, A.D.; Clapp, N.E. Jr.

    1992-01-01

    This paper presents a simulation study on the real-time process control network proposed for the new ANS reactor system at ORNL. A background discussion is provided on networks, modeling, and simulation, followed by an overview of the ANS process control network, its three peak-load models, and the results of a series of coarse-grained simulation studies carried out on these models using implementations of 802.3, 802.4, and 802.5 standard local area networks

  3. Loading pattern optimization by multi-objective simulated annealing with screening technique

    International Nuclear Information System (INIS)

    Tong, K. P.; Hyun, C. L.; Hyung, K. J.; Chang, H. K.

    2006-01-01

    This paper presents a new multi-objective function which is made up of the main objective term as well as penalty terms related to the constraints. All the terms are represented in the same functional form and the coefficient of each term is normalized so that each term has equal weighting in the subsequent simulated annealing optimization calculations. The screening technique introduced in the previous work is also adopted in order to save computer time in 3-D neutronics evaluation of trial loading patterns. For numerical test of the new multi-objective function in the loading pattern optimization, the optimum loading patterns for the initial and the cycle 7 reload PWR core of Yonggwang Unit 4 are calculated by the simulated annealing algorithm with screening technique. A total of 10 optimum loading patterns are obtained for the initial core through 10 independent simulated annealing optimization runs. For the cycle 7 reload core one optimum loading pattern has been obtained from a single simulated annealing optimization run. More SA optimization runs will be conducted to optimum loading patterns for the cycle 7 reload core and results will be presented in the further work. (authors)

  4. Temporal pattern of emotions and cognitive load during simulation training and debriefing.

    Science.gov (United States)

    Fraser, Kristin; McLaughlin, Kevin

    2018-04-24

    In the simulated clinical environment, there is a perceived benefit to the emotional activation experienced by learners; however, potential harm of excessive and/or negative emotions has also been hypothesized. An improved understanding of the emotional experiences of learners during each phase of the simulation session will inform instructional design. In this observational study, we asked 174 first-year medical students about their emotional state upon arrival to the simulation lab (t1). They were then trained on a standard simulation scenario, after which they rated their emotional state and perceived cognitive load (t2). After debriefing, we then asked them to again rate their emotions and cognitive load (t3). Students reported that their experience of tranquility (a positive and low-arousal state) dropped from pre-scenario (t1) to post-scenario (t2), and returned to baseline levels after debriefing (t3), from 0.69 (0.87) to 0.14 (0.78) to 0.62 (0.78). Post scenario cognitive load was rated to be moderately high at 6.62 (1.12) and scores increased after debriefing to 6.90 (1.05) d = 0.26, p Cognitive load was associated with the simultaneous measures of emotions at both t2 and t3. Participant emotions are significantly altered through the experience of medical simulation and emotions are associated with subjective ratings of cognitive load.

  5. Equivalent circuit simulation of HPEM-induced transient responses at nonlinear loads

    Directory of Open Access Journals (Sweden)

    M. Kotzev

    2017-09-01

    Full Text Available In this paper the equivalent circuit modeling of a nonlinearly loaded loop antenna and its transient responses to HPEM field excitations are investigated. For the circuit modeling the general strategy to characterize the nonlinearly loaded antenna by a linear and a nonlinear circuit part is pursued. The linear circuit part can be determined by standard methods of antenna theory and numerical field computation. The modeling of the nonlinear circuit part requires realistic circuit models of the nonlinear loads that are given by Schottky diodes. Combining both parts, appropriate circuit models are obtained and analyzed by means of a standard SPICE circuit simulator. It is the main result that in this way full-wave simulation results can be reproduced. Furthermore it is clearly seen that the equivalent circuit modeling offers considerable advantages with respect to computation speed and also leads to improved physical insights regarding the coupling between HPEM field excitation and nonlinearly loaded loop antenna.

  6. Assessing Fatigue and Ultimate Load Uncertainty in Floating Offshore Wind Turbines Due to Varying Simulation Length

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, G.; Lackner, M.; Haid, L.; Matha, D.; Jonkman, J.; Robertson, A.

    2013-07-01

    With the push towards siting wind turbines farther offshore due to higher wind quality and less visibility, floating offshore wind turbines, which can be located in deep water, are becoming an economically attractive option. The International Electrotechnical Commission's (IEC) 61400-3 design standard covers fixed-bottom offshore wind turbines, but there are a number of new research questions that need to be answered to modify these standards so that they are applicable to floating wind turbines. One issue is the appropriate simulation length needed for floating turbines. This paper will discuss the results from a study assessing the impact of simulation length on the ultimate and fatigue loads of the structure, and will address uncertainties associated with changing the simulation length for the analyzed floating platform. Recommendations of required simulation length based on load uncertainty will be made and compared to current simulation length requirements.

  7. Cyclic loading of simulated fault gouge to large strains

    Science.gov (United States)

    Jones, Lucile M.

    1980-04-01

    As part of a study of the mechanics of simulated fault gouge, deformation of Kayenta Sandstone (24% initial porosity) was observed in triaxial stress tests through several stress cycles. Between 50- and 300-MPa effective pressure the specimens deformed stably without stress drops and with deformation occurring throughout the sample. At 400-MPa effective pressure the specimens underwent strain softening with the deformation occurring along one plane. However, the difference in behavior seems to be due to the density variation at different pressures rather than to the difference in pressure. After peak stress was reached in each cycle, the samples dilated such that the volumetric strain and the linear strain maintained a constant ratio (approximately 0.1) at all pressures. The behavior was independent of the number of stress cycles to linear strains up to 90% and was in general agreement with laws of soil behavior derived from experiments conducted at low pressure (below 5 MPa).

  8. Development of Electronic Load Controllers for Free-Piston Stirling Convertors Aided by Stirling Simulation Model

    Science.gov (United States)

    Regan, Timothy F.

    2004-01-01

    The free-piston Stirling convertor end-to-end modeling effort at the NASA Glenn Research Center has produced a software-based test bed in which free-piston Stirling convertors can be simulated and evaluated. The simulation model includes all the components of the convertor: the Stirling cycle engine, heat source, linear alternator, controller, and load. So far, it has been used in evaluating the performance of electronic controller designs. Three different controller design concepts were simulated using the model: 1) Controllers with parasitic direct current loading. 2) Controllers with parasitic alternating current loading. 3) Controllers that maintain a reference current. The free-piston Stirling convertor is an electromechanical device that operates at resonance. It is the function of the electronic load controller to ensure that the electrical load seen by the machine is always great enough to keep the amplitude of the piston and alternator oscillation at the rated value. This is done by regulating the load on the output bus. The controller monitors the instantaneous voltage, regulating it by switching loads called parasitic loads onto the bus whenever the bus voltage is too high and removing them whenever the voltage is too low. In the first type of controller, the monitor-ing and switching are done on the direct-current (dc) bus. In the second type, the alternating current bus is used. The model allows designers to test a controller concept before investing time in hardware. The simulation code used to develop the model also offers detailed models of digital and analog electronic components so that the resulting designs are realistic enough to translate directly into hardware circuits.

  9. Unsteady hydraulic simulation of the cavitating part load vortex rope in Francis turbines

    Science.gov (United States)

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

    2017-04-01

    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.

  10. Static and dynamic load-balancing strategies for parallel reservoir simulation

    International Nuclear Information System (INIS)

    Anguille, L.; Killough, J.E.; Li, T.M.C.; Toepfer, J.L.

    1995-01-01

    Accurate simulation of the complex phenomena that occur in flow in porous media can tax even the most powerful serial computers. Emergence of new parallel computer architectures as a future efficient tool in reservoir simulation may overcome this difficulty. Unfortunately, major problems remain to be solved before using parallel computers commercially: production serial programs must be rewritten to be efficient in parallel environments and load balancing methods must be explored to evenly distribute the workload on each processor during the simulation. This study implements both a static load-balancing algorithm and a receiver-initiated dynamic load-sharing algorithm to achieve high parallel efficiencies on both the IBM SP2 and Intel IPSC/860 parallel computers. Significant speedup improvement was recorded for both methods. Further optimization of these algorithms yielded a technique with efficiencies as high as 90% and 70% on 8 and 32 nodes, respectively. The increased performance was the result of the minimization of message-passing overhead

  11. Empowering Critical Thinking Skills with Computerized Patient Simulators

    Science.gov (United States)

    Farrar, Francisca Cisneros; Suggs, Leslie

    2010-01-01

    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…

  12. Load-adaptive bone remodeling simulations reveal osteoporotic microstructural and mechanical changes in whole human vertebrae.

    Science.gov (United States)

    Badilatti, Sandro D; Christen, Patrik; Parkinson, Ian; Müller, Ralph

    2016-12-08

    Osteoporosis is a major medical burden and its impact is expected to increase in our aging society. It is associated with low bone density and microstructural deterioration. Treatments are available, but the critical factor is to define individuals at risk from osteoporotic fractures. Computational simulations investigating not only changes in net bone tissue volume, but also changes in its microstructure where osteoporotic deterioration occur might help to better predict the risk of fractures. In this study, bone remodeling simulations with a mechanical feedback loop were used to predict microstructural changes due to osteoporosis and their impact on bone fragility from 50 to 80 years of age. Starting from homeostatic bone remodeling of a group of seven, mixed sex whole vertebrae, five mechanostat models mimicking different biological alterations associated with osteoporosis were developed, leading to imbalanced bone formation and resorption with a total net loss of bone tissue. A model with reduced bone formation rate and cell sensitivity led to the best match of morphometric indices compared to literature data and was chosen to predict postmenopausal osteoporotic bone loss in the whole group. Thirty years of osteoporotic bone loss were predicted with changes in morphometric indices in agreement with experimental measurements, and only showing major deviations in trabecular number and trabecular separation. In particular, although being optimized to match to the morphometric indices alone, the predicted bone loss revealed realistic changes on the organ level and on biomechanical competence. While the osteoporotic bone was able to maintain the mechanical stability to a great extent, higher fragility towards error loads was found for the osteoporotic bones. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Critical thinking skills in nursing students: comparison of simulation-based performance with metrics

    Science.gov (United States)

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

    2018-01-01

    Aim This paper is a report of an examination of the relationship between metrics of critical thinking skills and performance in simulated clinical scenarios. Background Paper and pencil assessments are commonly used to assess critical thinking but may not reflect simulated performance. Methods 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. Results 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 video-taped 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). Conclusion 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

  14. Critical thinking skills in nursing students: comparison of simulation-based performance with metrics.

    Science.gov (United States)

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

    2010-10-01

    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

  15. Study on the reactivity behavior partially loaded reactor cores using SIMULATE-3

    International Nuclear Information System (INIS)

    Holzer, Robert; Zeitz, Andreas; Grimminger, Werner; Lubczyk, Tobias

    2009-01-01

    The reactor core design for the NPP Gundremmingen unit B and C is performed since several years using the validated 3D reactor core calculation program SIMULATE-3. The authors describe a special application of the program to study the reactivity for different partial core loadings. Based on the comparison with results of the program CASMO-4 the program SIMULATE-3 was validated for the calculation of partially loaded reactor cores. For the planned reactor operation in NPP Gundremmingen using new MOX fuel elements the reactivity behavior was studied with respect to the KTA-Code requirements.

  16. Expected load spectra of prototype Francis turbines in low-load operation using numerical simulations and site measurements

    Science.gov (United States)

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

    2017-04-01

    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.

  17. Critical acceleration of finite temperature SU(2) gauge simulations

    International Nuclear Information System (INIS)

    Ben-Av, R.; Marcu, M.; Hamburg Univ.; Solomon, S.

    1991-04-01

    We present a cluster algorithm that strongly reduces critical slowing down for the SU(2) gauge theory on one time slice. The idea that underlies the new algorithm is to perform efficient flips for the signs of Polyakov loops. Ergodicity is ensured by combining it with a standard local algorithm. We show how to quantify critical slowing down for such a mixed algorithm. At the finite temperature transition, the dynamical critical exponent z is ≅0.5, whereas for the purely local algoirthm z ≅ 2. (orig.)

  18. Effects of running with backpack loads during simulated gravitational transitions: Improvements in postural control

    Science.gov (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.

  19. Cognitive load, emotion, and performance in high-fidelity simulation among beginning nursing students: a pilot study.

    Science.gov (United States)

    Schlairet, Maura C; Schlairet, Timothy James; Sauls, Denise H; Bellflowers, Lois

    2015-03-01

    Establishing the impact of the high-fidelity simulation environment on student performance, as well as identifying factors that could predict learning, would refine simulation outcome expectations among educators. The purpose of this quasi-experimental pilot study was to explore the impact of simulation on emotion and cognitive load among beginning nursing students. Forty baccalaureate nursing students participated in teaching simulations, rated their emotional state and cognitive load, and completed evaluation simulations. Two principal components of emotion were identified representing the pleasant activation and pleasant deactivation components of affect. Mean rating of cognitive load following simulation was high. Linear regression identiffed slight but statistically nonsignificant positive associations between principal components of emotion and cognitive load. Logistic regression identified a negative but statistically nonsignificant effect of cognitive load on assessment performance. Among lower ability students, a more pronounced effect of cognitive load on assessment performance was observed; this also was statistically non-significant. Copyright 2015, SLACK Incorporated.

  20. Critical undrained shear strength of sand-silt mixtures under monotonic loading

    Directory of Open Access Journals (Sweden)

    Mohamed Bensoula

    2014-07-01

    Full Text Available This study uses experimental triaxial tests with monotonic loading to develop empirical relationships to estimate undrained critical shear strength. The effect of the fines content on undrained shear strength is analyzed for different density states. The parametric analysis indicates that, based on the soil void ratio and fine content properties, the undrained critical shear strength first increases and then decreases as the proportion of fines increases, which demonstrates the influence of fine content on a soil’s vulnerability to liquefaction. A series of monotonic undrained triaxial tests were performed on reconstituted saturated sand-silt mixtures. Beyond 30% fines content, a fraction of the silt participates in the soil’s skeleton chain force. In this context, the concept of the equivalent intergranular void ratio may be an appropriate parameter to express the critical shear strength of the studied soil. This parameter is able to control the undrained shear strength of non-plastic silt and sand mixtures with different densities.   Resumen Este estudio utiliza evaluaciones experimentales triaxiales con cargas repetitivas para desarrollar relaciones empíricas y estimar la tensión crítica de corte bajo condiciones no drenadas. El efecto de contenido de finos en la tensión de corte sin drenar se analizó en diferentes estados de densidad. El análisis paramétrico indica que, basado en la porosidad del suelo y las propiedades del material de finos, la tensión de corte sin drenar primero se incrementa y luego decrece mientras la proporción de finos aumenta, lo que demuestra la influencia de contenido de finos en la vulnerabilidad del suelo a la licuación. Una serie de las evaluaciones se realizó en  mezclas rehidratadas y saturadas de arena y cieno. Más allá del 30 % de los contenidos finos, una fracción del cieno hace parte principal de la cadena de fuerza del suelo. En este contexto, el concepto de porosidad equivalente

  1. CFD simulation of estimating critical shear stress for cleaning flat ...

    Indian Academy of Sciences (India)

    Sumit Kawale

    2017-11-22

    Nov 22, 2017 ... Jet impingement; wall shear stress; cleaning of flat plate; turbulence model; critical shear stress; ... On comparing the theoretical predictions with wall shear ... distance and Reynolds number on peak value of local shear stress ...

  2. Optimizing load transfer in multiwall nanotubes through interwall coupling: Theory and simulation

    International Nuclear Information System (INIS)

    Byrne, E.M.; Letertre, A.; McCarthy, M.A.; Curtin, W.A.; Xia, Z.

    2010-01-01

    An analytical model is developed to determine the length scales over which load is transferred from outer to inner walls of multiwall carbon nanotubes (MWCNTs) as a function of the amount of bonding between walls. The model predicts that the characteristic length for load transfer scales as l∼t√(E/μ-bar), where t is the CNT wall spacing, E is the effective wall Young's modulus, and μ-bar is the average interwall shear modulus due to interwall coupling. Molecular dynamics simulations for MWCNTs with up to six walls, and with interwall coupling achieved by interwall sp 3 bonding at various densities, provide data against which the model is tested. For interwall bonding having a uniform axial distribution, the analytic and simulation models agree well, showing that continuum mechanics concepts apply down to the atomic scale in this problem. The simulation models show, however, that load transfer is sensitive to natural statistical fluctuations in the spatial distribution of the interwall bonding between pairs of walls, and such fluctuations generally increase the net load transfer length needed to fully load an MWCNT. Optimal load transfer is achieved when bonding is uniformly distributed axially, and all interwall regions have the same shear stiffness, implying a linear decrease in the number of interwall bonds with distance from the outer wall. Optimal load transfer into an n-wall MWCNT is shown to occur over a length of ∼1.5nl. The model can be used to design MWCNTs for structural materials, and to interpret load transfer characteristics deduced from experiments on individual MWCNTs.

  3. Impact of Hypobarism During Simulated Transport on Critical Care Air Transport Team Performance

    Science.gov (United States)

    2017-04-26

    AFRL-SA-WP-SR-2017-0008 Impact of Hypobarism During Simulated Transport on Critical Care Air Transport Team Performance Dina...July 2014 – November 2016 4. TITLE AND SUBTITLE Impact of Hypobarism During Simulated Transport on Critical Care Air Transport Team Performance 5a...During Critical Care Air Transport Team Advanced Course validation, three-member teams consisting of a physician, nurse, and respiratory therapist

  4. Critical phosphorus loading of different types of shallow lakes and the consequences for management estimated with the ecosystem model PCLake

    NARCIS (Netherlands)

    Janse, J.H.; De Senerpont Domis, L.N.; Scheffer, M.; Lijklema, L.; Klinge, M.; Mooij, W.M.; Van Liere, L.

    2008-01-01

    Shallow lakes typically can be in one of two contrasting states: a clear state with submerged macrophytes or a turbid state dominated by phytoplankton. Eutrophication may cause a switch from the clear to the turbid state, if the phosphorus loading exceeds a critical value. Recovery of the clear

  5. Simulation of control performance under house load transients for nuclear power plant

    International Nuclear Information System (INIS)

    Liao Zhongyue; Wang Yuanlong; Tang Yuyuan; Liu Jiong

    1999-01-01

    The CATIA2 code is used to simulate the extreme normal transients--house load transients of Qinshan Phase II 600 MW nuclear power plant. The simulating results show that all of the reactor main parameters are operating in the allowable ranges, the reactor system is stable, and the control characteristics of the nuclear power plant is satisfactory. They are also good in agreement with Framatome's results

  6. Nuclear criticality safety: general. 4. The CASTOR X/32S Method of Covering mis-loading Concerns

    International Nuclear Information System (INIS)

    Lancaster, Dale B.; Rombough, Charles T.; Diersch, Rudolf; Spilker, Harry

    2001-01-01

    In the United States, most cask licenses do not directly consider mis-loading. If the enrichment limit for a shipping cask is high and the reactivity control is inherent in the cask, the reactivity effect of a mis-load is small. However, in large-capacity casks, such as the CASTOR X/32S, the effect can be much larger. The U.S. Department of Energy Topical Report on Actinide- Only Burnup Credit takes the position that a fuel assembly mis-load does need to be analyzed since there are multiple independent checks, and thus, the double-contingency principle is met. Unfortunately, 11 assemblies were mis-loaded at Palisades. This event has caused the U.S. Nuclear Regulatory Commission (NRC) to ask for more detail on prevention of mis-loading. In the summer of 1999, Palisades loaded 11 assemblies, which did not comply with the loading requirements for their VSC-24 cask. The cask requires 5 yr of cooling, and these 11 assemblies had just a little more than 4 yr of cooling. The mis-loading did not result in an unsafe condition but in an un-reviewed condition. This mis-loading was not identified until November 2000 during a review related to an NRC information notice. The loading plan for the cask was incorrect. The engineering review of the loading plan missed the error. The operators had loaded the cask consistent with the loading plan. The cask loading was then confirmed by comparing to the loading plan. The loading plan was in error since the engineer assumed that the entire region of fuel was discharged at the same time. The 11 assemblies of concern were reinserted in the reactor, and the engineer and the reviewer did not check for this. The reactor records for all the assemblies were correct but apparently were not checked by the engineer who created the loading plan. To prevent a mis-load criticality event, the following steps will be required for the CASTOR X/32S storage and transport cask: 1. A loading plan will be prepared for each cask loaded. This plan will be

  7. Development of Fast-Running Simulation Methodology Using Neural Networks for Load Follow Operation

    International Nuclear Information System (INIS)

    Seong, Seung-Hwan; Park, Heui-Youn; Kim, Dong-Hoon; Suh, Yong-Suk; Hur, Seop; Koo, In-Soo; Lee, Un-Chul; Jang, Jin-Wook; Shin, Yong-Chul

    2002-01-01

    A new fast-running analytic model has been developed for analyzing the load follow operation. The new model was based on the neural network theory, which has the capability of modeling the input/output relationships of a nonlinear system. The new model is made up of two error back-propagation neural networks and procedures to calculate core parameters, such as the distributions and density of xenon in a quasi-steady-state core like load follow operation. One neural network is designed to retrieve the axial offset of power distribution, and the other is for reactivity corresponding to a given core condition. The training data sets for learning the neural networks in the new model are generated with a three-dimensional nodal code and, also, the measured data of the first-day test of load follow operation. Using the new model, the simulation results of the 5-day load follow test in a pressurized water reactor show a good agreement between the simulation data and the actual measured data. Required computing time for simulating a load follow operation is comparable to that of a fast-running lumped model. Moreover, the new model does not require additional engineering factors to compensate for the difference between the actual measurements and analysis results because the neural network has the inherent learning capability of neural networks to new situations

  8. Simulation of reinforced concrete short shear wall subjected to cyclic loading

    International Nuclear Information System (INIS)

    Parulekar, Y.M.; Reddy, G.R.; Vaze, K.K.; Pegon, P.; Wenzel, H.

    2014-01-01

    Highlights: • Prediction of the capacity of squat shear wall using tests and analysis. • Modification of model of concrete in the softening part. • Pushover analysis using softened truss theory and FE analysis is performed. • Modified concrete model gives reasonable accurate peak load and displacement. • The ductility, ultimate load and also crack pattern can be accurately predicted. - Abstract: This paper addresses the strength and deformation capacity of stiff squat shear wall subjected to monotonic and pseudo-static cyclic loading using experiments and analysis. Reinforced concrete squat shear walls offer great potential for lateral load resistance and the failure mode of these shear walls is brittle shear mode. Shear strength of these shear walls depend strongly on softening of concrete struts in principal compression direction due to principal tension in other direction. In this work simulation of the behavior of a squat shear wall is accurately predicted by finite element modeling by incorporating the appropriate softening model in the program. Modification of model of concrete in the softening part is suggested and reduction factor given by Vecchio et al. (1994) is used in the model. The accuracy of modeling is confirmed by comparing the simulated response with experimental one. The crack pattern generated from the 3D model is compared with that obtained from experiments. The load deflection for monotonic loads is also obtained using softened truss theory and compared with experimental one

  9. Study on simulation methods of atrium building cooling load in hot and humid regions

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Yiqun; Li, Yuming; Huang, Zhizhong [Institute of Building Performance and Technology, Sino-German College of Applied Sciences, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Wu, Gang [Weldtech Technology (Shanghai) Co. Ltd. (China)

    2010-10-15

    In recent years, highly glazed atria are popular because of their architectural aesthetics and advantage of introducing daylight into inside. However, cooling load estimation of such atrium buildings is difficult due to complex thermal phenomena that occur in the atrium space. The study aims to find out a simplified method of estimating cooling loads through simulations for various types of atria in hot and humid regions. Atrium buildings are divided into different types. For every type of atrium buildings, both CFD and energy models are developed. A standard method versus the simplified one is proposed to simulate cooling load of atria in EnergyPlus based on different room air temperature patterns as a result from CFD simulation. It incorporates CFD results as input into non-dimensional height room air models in EnergyPlus, and the simulation results are defined as a baseline model in order to compare with the results from the simplified method for every category of atrium buildings. In order to further validate the simplified method an actual atrium office building is tested on site in a typical summer day and measured results are compared with simulation results using the simplified methods. Finally, appropriate methods of simulating different types of atrium buildings are proposed. (author)

  10. STRESS LOADING SIMULATION OF HYDRO-MECHANICAL TRANSMISSION OF DUMP TRUCK

    Directory of Open Access Journals (Sweden)

    S. A. Sidorov

    2006-01-01

    Full Text Available The Transmission model and software package to investigate stress loading of a hydromechanical transmission of a dump truck have been developed. The given software package allows to model stress loading of transmission gears in taking-off and acceleration modes at various road resistance, positions of an engine control pedal and initial revolutions of an engine crankshaft, various laws of friction clutch switching and some other parameters that permit to reveal a rate of various operational mode influence on stress loading of a dump truck transmission. An equivalence of the developed software is proved by the comparison of the experimentally obtained stress loading process of the hydro-mechanical transmission of a BelAZ- 7555 dump truck with the results of the simulation 

  11. Erosion simulation of first wall beryllium armour under ITER transient heat loads

    Science.gov (United States)

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

    2009-04-01

    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.

  12. Erosion simulation of first wall beryllium armour under ITER transient heat loads

    Energy Technology Data Exchange (ETDEWEB)

    Bazylev, B. [Forschungszentrum Karlsruhe, IHM, P.O. Box 3640, 76021 Karlsruhe (Germany)], E-mail: bazylev@ihm.fzk.de; Janeschitz, G. [Forschungszentrum Karlsruhe, Fusion, P.O. Box 3640, 76021 Karlsruhe (Germany); Landman, I.; Pestchanyi, S. [Forschungszentrum Karlsruhe, IHM, P.O. Box 3640, 76021 Karlsruhe (Germany); Loarte, A. [ITER Organisation, Cadarache, 13108 Saint Paul Lez Durance Cedex (France)

    2009-04-30

    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. Erosion simulation of first wall beryllium armour under ITER transient heat loads

    International Nuclear Information System (INIS)

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

    2009-01-01

    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.

  14. Intraoperative Noise Increases Perceived Task Load and Fatigue in Anesthesiology Residents: A Simulation-Based Study.

    Science.gov (United States)

    McNeer, Richard R; Bennett, Christopher L; Dudaryk, Roman

    2016-02-01

    Operating rooms are identified as being one of the noisiest of clinical environments, and intraoperative noise is associated with adverse effects on staff and patient safety. Simulation-based experiments would offer controllable and safe venues for investigating this noise problem. However, realistic simulation of the clinical auditory environment is rare in current simulators. Therefore, we retrofitted our operating room simulator to be able to produce immersive auditory simulations with the use of typical sound sources encountered during surgeries. Then, we tested the hypothesis that anesthesia residents would perceive greater task load and fatigue while being given simulated lunch breaks in noisy environments rather than in quiet ones. As a secondary objective, we proposed and tested the plausibility of a novel psychometric instrument for the assessment of stress. In this simulation-based, randomized, repeated-measures, crossover study, 2 validated psychometric survey instruments, the NASA Task Load Index (NASA-TLX), composed of 6 items, and the Swedish Occupational Fatigue Inventory (SOFI), composed of 5 items, were used to assess perceived task load and fatigue, respectively, in first-year anesthesia residents. Residents completed the psychometric instruments after being given lunch breaks in quiet and noisy intraoperative environments (soundscapes). The effects of soundscape grouping on the psychometric instruments and their comprising items were analyzed with a split-plot analysis. A model for a new psychometric instrument for measuring stress that combines the NASA-TLX and SOFI instruments was proposed, and a factor analysis was performed on the collected data to determine the model's plausibility. Twenty residents participated in this study. Multivariate analysis of variance showed an effect of soundscape grouping on the combined NASA-TLX and SOFI instrument items (P = 0.003) and the comparisons of univariate item reached significance for the NASA Temporal

  15. DIESIS : An Interoperable European Federated Simulation Network for Critical Infrastructures

    NARCIS (Netherlands)

    Rome, E.; Bologna, S.; Gelenbe, E.; Luiijf, H.A.M.; Masucci, V.

    2009-01-01

    Critical Infrastructures (CI) that are vital for a society and an economy, such as telecommunication systems, energy supply systems, transport systems and others, are getting more and more complex. Dependencies emerge in various ways, due to the use of information and communication technologies,

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

    Directory of Open Access Journals (Sweden)

    Isaac WONG

    2010-08-01

    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.

  17. Experimental critical loadings and control rod worths in LWR-PROTEUS configurations compared with MCNPX results

    International Nuclear Information System (INIS)

    Plaschy, M.; Murphy, M.; Jatuff, F.; Seiler, R.; Chawla, R.

    2006-01-01

    The PROTEUS research reactor at the Paul Scherrer Inst. (PSI) has been operating since the sixties and has already permitted, due to its high flexibility, investigation of a large range of very different nuclear systems. Currently, the ongoing experimental programme is called LWR-PROTEUS. This programme was started in 1997 and concerns large-scale investigations of advanced light water reactors (LWR) fuels. Until now, the different LWR-PROTEUS phases have permitted to study more than fifteen different configurations, each of them having to be demonstrated to be operationally safe, in particular, for the Swiss safety authorities. In this context, recent developments of the PSI computer capabilities have made possible the use of full-scale SD-heterogeneous MCNPX models to calculate accurately different safety related parameters (e.g. the critical driver loading and the shutdown rod worth). The current paper presents the MCNPX predictions of these operational characteristics for seven different LWR-PROTEUS configurations using a large number of nuclear data libraries. More specifically, this significant benchmarking exercise is based on the ENDF/B6v2, ENDF/B6v8, JEF2.2, JEFF3.0, JENDL3.2, and JENDL3.3 libraries. The results highlight certain library specific trends in the prediction of the multiplication factor k eff (e.g. the systematically larger reactivity calculated with JEF2.2 and the smaller reactivity associated with JEFF3.0). They also confirm the satisfactory determination of reactivity variations by all calculational schemes, for instance, due to the introduction of a safety rod pair, these calculations having been compared with experiments. (authors)

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

    KAUST Repository

    Yucel, Abdulkadir C.; Sheng, Weitian; Zhou, Chenming; Liu, Yang Z.; Bagci, Hakan; Michielssen, Eric

    2018-01-01

    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

  19. Simulation of wind loads on facades - Out in the wind; Simulation von Windlasten auf Fassaden. Vom Winde umstroemt

    Energy Technology Data Exchange (ETDEWEB)

    Menti, U.-P.; Pluess, I.

    2007-07-01

    This illustrated article discusses the wind loads experienced by buildings at exposed locations and, in particular, the correct design of their facades. The various numerical methods such as computational fluid dynamics (CFD) available for this purpose are introduced and explained. The validation of the models is discussed and the simulation of wind loads on the new revolving restaurant on the Hohe Kasten mountain in eastern Switzerland is looked at. Here winds with speeds of up to 250 km/h from various directions can be expected. Illustrations are provided of the results obtained. Practical results obtained from the simulations such as the design of the building's facades and the correct placing of air vents are presented and discussed.

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

    Directory of Open Access Journals (Sweden)

    Wang Chao

    2016-03-01

    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.

  1. Improving Middle School Students’ Critical Thinking Skills Through Reading Infusion-Loaded Discovery Learning Model in the Science Instruction

    Science.gov (United States)

    Nuryakin; Riandi

    2017-02-01

    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.

  2. Utilizing a Simulation Exercise to Illustrate Critical Inventory Management Concepts

    Science.gov (United States)

    Umble, Elisabeth; Umble, Michael

    2013-01-01

    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…

  3. Language Simulations: The Blending Space for Writing and Critical Thinking

    Science.gov (United States)

    Kovalik, Doina L.; Kovalik, Ludovic M.

    2007-01-01

    This article describes a language simulation involving six distinct phases: an in-class quick response, a card game, individual research, a classroom debate, a debriefing session, and an argumentative essay. An analysis of student artifacts--quick-response writings and final essays, respectively, both addressing the definition of liberty in a…

  4. Power load limits of the WENDELSTEIN 7-X target elements-comparison of experimental results and design values for power loads up to the critical heat flux

    International Nuclear Information System (INIS)

    Greuner, H; Boeswirth, B; Boscary, J; Leuprecht, A; Plankensteiner, A

    2007-01-01

    The power load limits of the WENDELSTEIN7-X divertor target elements were experimentally evaluated with heat loads considerably exceeding the expected operating conditions. The water-cooled elements are designed for steady-state heat flux of 10 MW m -2 and to remove a power load up to 100 kW. The elements must allow a limited operation time at 12 MW m -2 steady-state and should not fail for short pulses of up to 15 MW m -2 for cooling conditions in the subcooled nucleate boiling regime. In the framework of the qualification phase, pre-series target elements were loaded up to 24 MW m -2 without loss of CFC tiles. A critical heat flux at the target of 31 MW m -2 was achieved. The paper discusses the results of the tests performed at the high heat flux test facility GLADIS. The experimental results compared to transient nonlinear fine element method (FEM) calculations confirm a high thermal safety margin of the target design sufficient for plasma operation in W7-X

  5. Effect of cognitive load on speech prosody in aviation: Evidence from military simulator flights.

    Science.gov (United States)

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

    2011-01-01

    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.

  6. Finite Element Simulation of Medium-Range Blast Loading Using LS-DYNA

    Directory of Open Access Journals (Sweden)

    Yuzhen Han

    2015-01-01

    Full Text Available This study investigated the Finite Element simulation of blast loading using LS-DYNA. The objective is to identify approaches to reduce the requirement of computation effort while maintaining reasonable accuracy, focusing on blast loading scheme, element size, and its relationship with scale of explosion. The study made use of the recently developed blast loading scheme in LS-DYNA, which removes the necessity to model the explosive in the numerical models but still maintains the advantages of nonlinear fluid-structure interaction. It was found that the blast loading technique could significantly reduce the computation effort. It was also found that the initial density of air in the numerical model could be purposely increased to partially compensate the error induced by the use of relatively large air elements. Using the numerical approach, free air blast above a scaled distance of 0.4 m/kg1/3 was properly simulated, and the fluid-structure interaction at the same location could be properly duplicated using proper Arbitrary Lagrangian Eulerian (ALE coupling scheme. The study also showed that centrifuge technique, which has been successfully employed in model tests to investigate the blast effects, may be used when simulating the effect of medium- to large-scale explosion at small scaled distance.

  7. 10^{7}-A load-current B-dot monitor: Simulations, design, and performance

    Directory of Open Access Journals (Sweden)

    D. V. Rose

    2010-04-01

    Full Text Available A B-dot monitor that measures the current 6 cm from the axis of dynamic loads fielded on 10^{7}-A multiterawatt pulsed-power accelerators has been developed. The monitor improves upon the multimegampere load-current gauge described in Phys. Rev. ST Accel. Beams 11, 100401 (2008PRABFM1098-440210.1103/PhysRevSTAB.11.100401. The design of the improved monitor was developed using three-dimensional particle-in-cell simulations that model vacuum electron flow in the transmission line near the monitor. The simulations include important geometric features of the B-dot probe and model the deposition of electron energy within the probe. The simulations show that the improved design reduces by as much as a factor of 5 the electron energy deposition to the interior of the monitor. Data taken on accelerator shots demonstrate that the improved monitor works as well as the original monitor on shots with low-impedance loads, and delivers superior performance on higher-impedance-load shots.

  8. Simulation of pore pressure accumulation under cyclic loading using Finite Volume Method

    DEFF Research Database (Denmark)

    Tang, Tian; Hededal, Ole

    2014-01-01

    This paper presents a finite volume implementation of a porous, nonlinear soil model capable of simulating pore pressure accumulation under cyclic loading. The mathematical formulations are based on modified Biot’s coupled theory by substituting the original elastic constitutive model...... with an advanced elastoplastic model suitable for describing monotonic as well as cyclic loading conditions. The finite volume method is applied to discretize these formulations. The resulting set of coupled nonlinear algebraic equations are then solved by a ’segregated’ solution procedure. An efficient return...

  9. Efficient graph-based dynamic load-balancing for parallel large-scale agent-based traffic simulation

    NARCIS (Netherlands)

    Xu, Y.; Cai, W.; Aydt, H.; Lees, M.; Tolk, A.; Diallo, S.Y.; Ryzhov, I.O.; Yilmaz, L.; Buckley, S.; Miller, J.A.

    2014-01-01

    One of the issues of parallelizing large-scale agent-based traffic simulations is partitioning and load-balancing. Traffic simulations are dynamic applications where the distribution of workload in the spatial domain constantly changes. Dynamic load-balancing at run-time has shown better efficiency

  10. Molecular Simulations of Cyclic Loading Behavior of Carbon Nanotubes Using the Atomistic Finite Element Method

    Directory of Open Access Journals (Sweden)

    Jianfeng Wang

    2009-01-01

    Full Text Available The potential applications of carbon nanotubes (CNT in many engineered bionanomaterials and electromechanical devices have imposed an urgent need on the understanding of the fatigue behavior and mechanism of CNT under cyclic loading conditions. To date, however, very little work has been done in this field. This paper presents the results of a theoretical study on the behavior of CNT subject to cyclic tensile and compressive loads using quasi-static molecular simulations. The Atomistic Finite Element Method (AFEM has been applied in the study. It is shown that CNT exhibited extreme cyclic loading resistance with yielding strain and strength becoming constant within limited number of loading cycles. Viscoelastic behavior including nonlinear elasticity, hysteresis, preconditioning (stress softening, and large strain have been observed. Chiral symmetry was found to have appreciable effects on the cyclic loading behavior of CNT. Mechanisms of the observed behavior have been revealed by close examination of the intrinsic geometric and mechanical features of tube structure. It was shown that the accumulated residual defect-free morphological deformation was the primary mechanism responsible for the cyclic failure of CNT, while the bond rotating and stretching experienced during loading/unloading played a dominant role on the strength, strain and modulus behavior of CNT.

  11. 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

    2016-09-01

    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.

  12. Simulation of fatigue damage in ferroelectric polycrystals under mechanical/electrical loading

    Science.gov (United States)

    Kozinov, S.; Kuna, M.

    2018-07-01

    The reliability of smart-structures made of ferroelectric ceramics is essentially reduced by the formation of cracks under the action of external electrical and/or mechanical loading. In the current research a numerical model for low-cycle fatigue in ferroelectric mesostructures is proposed. In the finite element simulations a combination of two user element routines is utilized. The first one is used to model a micromechanical ferroelectric domain switching behavior inside the grains. The second one is used to simulate fatigue damage of grain boundaries by a cohesive zone model (EMCCZM) based on an electromechanical cyclic traction-separation law (TSL). For numerical simulations a scanning electron microscope image of the ceramic's grain structure was digitalized and meshed. The response of this mesostructure to cyclic electrical or mechanical loading is systematically analyzed. As a result of the simulations, the distribution of electric potential, field, displacement and polarization as well as mechanical stresses and deformations inside the grains are obtained. At the grain boundaries, the formation and evolution of damage are analyzed until final failure and induced degradation of electric permittivity. It is found that the proposed model correctly mimics polycrystalline behavior during poling processes and progressive damage under cyclic electromechanical loading. To the authors' knowledge, it is the first model and numerical analysis of ferroelectric polycrystals taking into account both domain reorientation and cohesive modeling of intergranular fracture. It can help to understand failure mechanisms taking place in ferroelectrics during fatigue processes.

  13. Numerical simulation of thermal loading produced by shaped high power laser onto engine parts

    International Nuclear Information System (INIS)

    Song Hongwei; Li Shaoxia; Zhang Ling; Yu Gang; Zhou Liang; Tan Jiansong

    2010-01-01

    Recently a new method for simulating the thermal loading on pistons of diesel engines was reported. The spatially shaped high power laser is employed as the heat source, and some preliminary experimental and numerical work was carried out. In this paper, a further effort was made to extend this simulation method to some other important engine parts such as cylinder heads. The incident Gaussian beam was transformed into concentric multi-circular patterns of specific intensity distributions, with the aid of diffractive optical elements (DOEs). By incorporating the appropriate repetitive laser pulses, the designed transient temperature fields and thermal loadings in the engine parts could be simulated. Thermal-structural numerical models for pistons and cylinder heads were built to predict the transient temperature and thermal stress. The models were also employed to find the optimal intensity distributions of the transformed laser beam that could produce the target transient temperature fields. Comparison of experimental and numerical results demonstrated that this systematic approach is effective in simulating the thermal loading on the engine parts.

  14. Decoupled simulations of offshore wind turbines with reduced rotor loads and aerodynamic damping

    Directory of Open Access Journals (Sweden)

    S. Schafhirt

    2018-02-01

    Full Text Available Decoupled load simulations are a computationally efficient method to perform a dynamic analysis of an offshore wind turbine. Modelling the dynamic interactions between rotor and support structure, especially the damping caused by the rotating rotor, is of importance, since it influences the structural response significantly and has a major impact on estimating fatigue lifetime. Linear damping is usually used for this purpose, but experimentally and analytically derived formulas to calculate an aerodynamic damping ratio often show discrepancies to measurement and simulation data. In this study decoupled simulation methods with reduced and full rotor loads are compared to an integrated simulation. The accuracy of decoupled methods is evaluated and an optimization is performed to obtain aerodynamic damping ratios for different wind speeds that provide the best results with respect to variance and equivalent fatigue loads at distinct output locations. Results show that aerodynamic damping is not linear, but it is possible to match desired output using decoupled models. Moreover, damping ratios obtained from the empirical study suggest that aerodynamic damping increases for higher wind speeds.

  15. A PFC3D-based numerical simulation of cutting load for lunar rock simulant and experimental validation

    Science.gov (United States)

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

    2017-05-01

    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.

  16. Acid deposition and assessment of its critical load for the environmental health of waterbodies in a subtropical watershed, China

    Science.gov (United States)

    Jia, Junjie; Gao, Yang

    2017-12-01

    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.

  17. Simulated front crawl swimming performance related to critical speed and critical power.

    Science.gov (United States)

    Toussaint, H M; Wakayoshi, K; Hollander, A P; Ogita, F

    1998-01-01

    Competitive pool swimming events range in distance from 50 to 1500 m. Given the difference in performance times (+/- 23-1000 s), the contribution of the aerobic and anaerobic energy systems changes considerably with race distance. In training practice the regression line between swimming distance and time (Distance = critical velocity x time + anaerobic swimming capacity) is used to determine the individual capacity of the aerobic and anaerobic metabolic pathways. Although there is confidence that critical velocity and anaerobic swimming capacity are fitness measures that separate aerobic and anaerobic components, a firm theoretical basis for the interpretation of these results does not exist. The purpose of this study was to evaluate the critical power concept and anaerobic swimming capacity as measures of the aerobic and anaerobic capacity using a modeling approach. A systems model was developed that relates the mechanics and energetics involved in front crawl swimming performance. From actual swimming flume measurements, the time dependent aerobic and anaerobic energy release was modeled. Data derived from the literature were used to relate the energy cost of front crawl swimming to swimming velocity. A balance should exist between the energy cost to swim a distance in a certain time and the concomitant aerobic and anaerobic energy release. The ensuing model was used to predict performance times over a range of distances (50-1500 m) and to calculate the regression line between swimming distance and time. Using a sensitivity analysis, it was demonstrated that the critical velocity is indicative for the capacity of the aerobic energy system. Estimates of the anaerobic swimming capacity, however, were influenced by variations in both anaerobic and aerobic energy release. Therefore, it was concluded that the anaerobic swimming capacity does not provide a reliable estimate of the anaerobic capacity.

  18. Accurate and precise determination of critical properties from Gibbs ensemble Monte Carlo simulations

    International Nuclear Information System (INIS)

    Dinpajooh, Mohammadhasan; Bai, Peng; Allan, Douglas A.; Siepmann, J. Ilja

    2015-01-01

    Since the seminal paper by Panagiotopoulos [Mol. Phys. 61, 813 (1997)], the Gibbs ensemble Monte Carlo (GEMC) method has been the most popular particle-based simulation approach for the computation of vapor–liquid phase equilibria. However, the validity of GEMC simulations in the near-critical region has been questioned because rigorous finite-size scaling approaches cannot be applied to simulations with fluctuating volume. Valleau [Mol. Simul. 29, 627 (2003)] has argued that GEMC simulations would lead to a spurious overestimation of the critical temperature. More recently, Patel et al. [J. Chem. Phys. 134, 024101 (2011)] opined that the use of analytical tail corrections would be problematic in the near-critical region. To address these issues, we perform extensive GEMC simulations for Lennard-Jones particles in the near-critical region varying the system size, the overall system density, and the cutoff distance. For a system with N = 5500 particles, potential truncation at 8σ and analytical tail corrections, an extrapolation of GEMC simulation data at temperatures in the range from 1.27 to 1.305 yields T c = 1.3128 ± 0.0016, ρ c = 0.316 ± 0.004, and p c = 0.1274 ± 0.0013 in excellent agreement with the thermodynamic limit determined by Potoff and Panagiotopoulos [J. Chem. Phys. 109, 10914 (1998)] using grand canonical Monte Carlo simulations and finite-size scaling. Critical properties estimated using GEMC simulations with different overall system densities (0.296 ≤ ρ t ≤ 0.336) agree to within the statistical uncertainties. For simulations with tail corrections, data obtained using r cut = 3.5σ yield T c and p c that are higher by 0.2% and 1.4% than simulations with r cut = 5 and 8σ but still with overlapping 95% confidence intervals. In contrast, GEMC simulations with a truncated and shifted potential show that r cut = 8σ is insufficient to obtain accurate results. Additional GEMC simulations for hard-core square-well particles with various

  19. Colistin Population Pharmacokinetics after Application of a Loading Dose of 9 MU Colistin Methanesulfonate in Critically Ill Patients

    OpenAIRE

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

    2015-01-01

    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 ...

  20. Inter-annual variations in water yield to lakes in northeastern Alberta: implications for estimating critical loads of acidity

    Directory of Open Access Journals (Sweden)

    Roderick HAZEWINKEL

    2010-08-01

    Full Text Available Stable isotopes of water were applied to estimate water yield to fifty lakes in northeastern Alberta as part of an acid sensitivity study underway since 2002 in the Athabasca Oil Sands Region (AOSR. Herein, we apply site-specific water yields for each lake to calculate critical loads of acidity using water chemistry data and a steady-state water chemistry model. The main goal of this research was to improve site-specific critical load estimates and to understand the sensitivity to hydrologic variability across a Boreal Plains region under significant oil sands development pressure. Overall, catchment water yields were found to vary significantly over the seven year monitoring period, with distinct variations among lakes and between different regions, overprinted by inter-annual climate-driven shifts. Analysis of critical load estimates based on site-specific water yields suggests that caution must be applied to establish hydrologic conditions and define extremes at specific sites in order to protect more sensitive ecosystems. In general, lakes with low (high water yield tended to be more (less acid sensitive but were typically less (more affected by interannual hydrological variations. While it has been customary to use long-term water yields to define a static critical load for lakes, we find that spatial and temporal variability in water yield may limit effectiveness of this type of assessment in areas of the Boreal Plain characterized by heterogeneous runoff and without a long-term lake-gauging network. Implications for predicting acidification risk are discussed for the AOSR.

  1. Application of quasi-steady-state plasma streams for simulation of ITER transient heat loads

    International Nuclear Information System (INIS)

    Bandura, A.N.; Chebotarev, V.V.; Garkusha, I.E.; Makhlaj, V.A.; Marchenko, A.K.; Solyakov, D.G.; Tereshin, V.I.; Trubchaninov, S.A.; Tsarenko, A.V.; Landman, I.

    2004-01-01

    The paper presents experimental investigations of energy characteristics of the plasma streams generated with quasi-steady-state plasma accelerator QSPA Kh-50 and adjustment of plasma parameters from the point of view its applicability for simulation of transient plasma heat loads expected for ITER disruptions and type I ELMs. Possibility of generation of high-power magnetized plasma streams with ion impact energy up to 0.6 keV, pulse length of 0.25 ms and heat loads varied in wide range from 0.5 to 30 MJ/m 2 has been demonstrated and some features of plasma interaction with tungsten targets in dependence on plasma heat loads are discussed. (author)

  2. Efficient approach to simulate EM loads on massive structures in ITER machine

    Energy Technology Data Exchange (ETDEWEB)

    Alekseev, A. [ITER Organization, Route de Vinon sur Verdon, 13115 St. Paul-Lez-Durance (France); Andreeva, Z.; Belov, A.; Belyakov, V.; Filatov, O. [D.V. Efremov Scientific Research Institute, 196641 St. Petersburg (Russian Federation); Gribov, Yu.; Ioki, K. [ITER Organization, Route de Vinon sur Verdon, 13115 St. Paul-Lez-Durance (France); Kukhtin, V.; Labusov, A.; Lamzin, E.; Lyublin, B.; Malkov, A.; Mazul, I. [D.V. Efremov Scientific Research Institute, 196641 St. Petersburg (Russian Federation); Rozov, V.; Sugihara, M. [ITER Organization, Route de Vinon sur Verdon, 13115 St. Paul-Lez-Durance (France); Sychevsky, S., E-mail: sytch@sintez.niiefa.spb.su [D.V. Efremov Scientific Research Institute, 196641 St. Petersburg (Russian Federation)

    2013-10-15

    Highlights: ► A modelling technique to predict EM loads in ITER conducting structures is presented. ► The technique provides low computational cost and parallel computations. ► Detailed models were built for the system “vacuum vessel, cryostat, thermal shields”. ► EM loads on massive in-vessel structures were simulated with the use of local models. ► A flexible combination of models enables desired accuracy of load distributions. -- Abstract: Operation of the ITER machine is associated with high electromagnetic (EM) loads. An essential contributor to EM loads is eddy currents induced in passive conductive structures. Reasoning from the ITER construction, a modelling technique has been developed and applied in computations to efficiently predict anticipated loads. The technique allows us to avoid building a global 3D finite-element (FE) model that requires meshing of the conducting structures and their vacuum environment into 3D solid elements that leads to high computational cost. The key features of the proposed technique are: (i) the use of an existing shell model for the system “vacuum vessel (VV), cryostat, and thermal shields (TS)” implementing the magnetic shell approach. A solution is obtained in terms of a single-component, in this case, vector electric potential taken within the conducting shells of the “VV + cryostat + TS” system. (ii) EM loads on in-vessel conducting structures are simulated with the use of local FE models. The local models use either the 3D solid body or shell approximations. Reasoning from the simulation efficiency, the local boundary conditions are put with respect to the total field or an external field. The use of an integral-differential formulation and special procedures ensures smooth and accurate simulated distributions of fields from current sources of any geometry. The local FE models have been developed and applied for EM analyses of a variety of the ITER components including the diagnostic systems

  3. Erosion simulation of first wall beryllium armour under ITER transient heat loads

    Energy Technology Data Exchange (ETDEWEB)

    Bazylev, B.; Janeschitz, G. [Forschungszentrum Karlsruhe GmbH, FZK, Karlsruhe (Germany); Landman, I.; Pestchanyi, S. [FZK-Forschungszentrum Karlsruhe, Association Euratom-FZK, Technik und Umwelt, Karlsruhe (Germany); Loarte, A. [EFDA Close Support Unit Garching, Garching bei Munchen(Germany)

    2007-07-01

    Full text of publication follows: Operation of ITER at high fusion gain is assumed to be the H-mode. A characteristic feature of this regime is the transient release of energy from the confined plasma onto divertor and the first wall by multiple ELMs (about 10{sup 4} ELMs per ITER discharge), which can play a determining role in the erosion rate and lifetime of these components. It is expected that about 50-70 % of the ELM energy releases onto divertor armour and the rest is dumped onto the First Wall (FW) armour. The expected energy heat loads on the ITER divertor and FW during Type I ELM are in range 0.5 - 4 MJ/m{sup 2} in timescales of 0.3-0.6 ms. In case of the ITER disruptions the material evaporated from the divertor expands into the SOL and generates significant radiation heating of the FW armour up to several GW/m2 during a few milliseconds that can also lead to the its melting and noticeable damage. Beryllium macro-brush armour (Be-brushes) is foreseen as plasma FW facing component (PFC) in ITER. During the intense transient events in ITER the surface melting, melt motion, melt splashing and evaporation are seen as the main mechanisms of Be-erosion. The expected erosion of the ITER plasma facing components under transient energy loads can be properly estimated by numerical simulations using the codes MEMOS and PHEMOBRID validated against experimental data obtained at the plasma gun facilities QSPA-T, MK-200UG and QSPA-Kh50 that provide a way to simulate the energy loads expected in ITER in laboratory experiments. The numerical simulations were carried out for the expected ITER ELMs for the heat loads in the range 0.5 - 3.0 MJ/m{sup 2} and the timescale up 0.6 ms and ITER disruptions for the heat loads in the range 2 - 13 MJ/m{sup 2} in timescales of 1-5 ms. Radiation heat loads at the FW armour from the vapour expanded into the SOL were calculated using the codes FOREV-2 and TOKES for both ITER ELM and ITER disruption scenarios. Melt layer damage of the Be

  4. Erosion simulation of first wall beryllium armour under ITER transient heat loads

    International Nuclear Information System (INIS)

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

    2007-01-01

    Full text of publication follows: Operation of ITER at high fusion gain is assumed to be the H-mode. A characteristic feature of this regime is the transient release of energy from the confined plasma onto divertor and the first wall by multiple ELMs (about 10 4 ELMs per ITER discharge), which can play a determining role in the erosion rate and lifetime of these components. It is expected that about 50-70 % of the ELM energy releases onto divertor armour and the rest is dumped onto the First Wall (FW) armour. The expected energy heat loads on the ITER divertor and FW during Type I ELM are in range 0.5 - 4 MJ/m 2 in timescales of 0.3-0.6 ms. In case of the ITER disruptions the material evaporated from the divertor expands into the SOL and generates significant radiation heating of the FW armour up to several GW/m2 during a few milliseconds that can also lead to the its melting and noticeable damage. Beryllium macro-brush armour (Be-brushes) is foreseen as plasma FW facing component (PFC) in ITER. During the intense transient events in ITER the surface melting, melt motion, melt splashing and evaporation are seen as the main mechanisms of Be-erosion. The expected erosion of the ITER plasma facing components under transient energy loads can be properly estimated by numerical simulations using the codes MEMOS and PHEMOBRID validated against experimental data obtained at the plasma gun facilities QSPA-T, MK-200UG and QSPA-Kh50 that provide a way to simulate the energy loads expected in ITER in laboratory experiments. The numerical simulations were carried out for the expected ITER ELMs for the heat loads in the range 0.5 - 3.0 MJ/m 2 and the timescale up 0.6 ms and ITER disruptions for the heat loads in the range 2 - 13 MJ/m 2 in timescales of 1-5 ms. Radiation heat loads at the FW armour from the vapour expanded into the SOL were calculated using the codes FOREV-2 and TOKES for both ITER ELM and ITER disruption scenarios. Melt layer damage of the Be FW macro

  5. Ramifications of structural deformations on collapse loads of critically cracked pipe bends under in-plane bending and internal pressure

    Energy Technology Data Exchange (ETDEWEB)

    Sasidharan, Sumesh; Arunachalam, Veerappan; Subramaniam, Shanmugam [Dept. of Mechanical Engineering, National Institute of Technology, Tiruchirappalli (India)

    2017-02-15

    Finite-element analysis based on elastic-perfectly plastic material was conducted to examine the influence of structural deformations on collapse loads of circumferential through-wall critically cracked 90 .deg. pipe bends undergoing in-plane closing bending and internal pressure. The critical crack is defined for a through-wall circumferential crack at the extrados with a subtended angle below which there is no weakening effect on collapse moment of elbows subjected to in-plane closing bending. Elliptical and semioval cross sections were postulated at the bend regions and compared. Twice-elastic-slope method was utilized to obtain the collapse loads. Structural deformations, namely, ovality and thinning, were each varied from 0% to 20% in steps of 5% and the normalized internal pressure was varied from 0.2 to 0.6. Results indicate that elliptic cross sections were suitable for pipe ratios 5 and 10, whereas for pipe ratio 20, semioval cross sections gave satisfactory solutions. The effect of ovality on collapse loads is significant, although it cancelled out at a certain value of applied internal pressure. Thinning had a negligible effect on collapse loads of bends with crack geometries considered.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kolm, J; Vlaheli, A

    1996-10-01

    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

  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).

    Science.gov (United States)

    Zarifsanaiey, Nahid; Amini, Mitra; Saadat, Farideh

    2016-11-16

    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 B.to 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 critical thinking did not increase before and after the

  8. 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

    2018-01-01

    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.

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

    Science.gov (United States)

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

    2018-01-07

    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.

  10. Load-Unload Response Ratio and Accelerating Moment/Energy Release Critical Region Scaling and Earthquake Prediction

    Science.gov (United States)

    Yin, X. C.; Mora, P.; Peng, K.; Wang, Y. C.; Weatherley, D.

    The main idea of the Load-Unload Response Ratio (LURR) is that when a system is stable, its response to loading corresponds to its response to unloading, whereas when the system is approaching an unstable state, the response to loading and unloading becomes quite different. High LURR values and observations of Accelerating Moment/Energy Release (AMR/AER) prior to large earthquakes have led different research groups to suggest intermediate-term earthquake prediction is possible and imply that the LURR and AMR/AER observations may have a similar physical origin. To study this possibility, we conducted a retrospective examination of several Australian and Chinese earthquakes with magnitudes ranging from 5.0 to 7.9, including Australia's deadly Newcastle earthquake and the devastating Tangshan earthquake. Both LURR values and best-fit power-law time-to-failure functions were computed using data within a range of distances from the epicenter. Like the best-fit power-law fits in AMR/AER, the LURR value was optimal using data within a certain epicentral distance implying a critical region for LURR. Furthermore, LURR critical region size scales with mainshock magnitude and is similar to the AMR/AER critical region size. These results suggest a common physical origin for both the AMR/AER and LURR observations. Further research may provide clues that yield an understanding of this mechanism and help lead to a solid foundation for intermediate-term earthquake prediction.

  11. Investigation on pitch system loads by means of an integral multi body simulation approach

    Science.gov (United States)

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

    2016-09-01

    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.

  12. Experimental assessment of air permeability in a concrete shear wall subjected to simulated seismic loading

    International Nuclear Information System (INIS)

    Girrens, S.P.; Farrar, C.R.

    1991-07-01

    A safety concern for the proposed Special Nuclear Materials Laboratory (SNML) facility at the Los Alamos National Laboratory was air leakage from the facility if it were to experience a design basis earthquake event. To address this concern, a study was initiated to estimate air leakage, driven by wind-generated pressure gradients, from a seismically damaged concrete structure. This report describes a prototype experiment developed and performed to measure the air permeability in a reinforced concrete shear wall, both before and after simulated seismic loading. A shear wall test structure was fabricated with standard 4000-psi concrete mix. Static load-cycle testing was used to simulate earthquake loading. Permeability measurements were made by pressurizing one side of the shear wall above atmospheric conditions and recording the transient pressure decay. As long as the structure exhibited linear load displacement response, no variation in the air permeability was detected. However, experimental results indicate that the air permeability in the shear wall increased by a factor of 40 after the wall had been damaged (cracked). 17 figs., 8 tabs

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

    Directory of Open Access Journals (Sweden)

    Demić Miroslav D.

    2016-01-01

    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.

  14. The effect of distributed virtual reality simulation training on cognitive load during subsequent dissection training.

    Science.gov (United States)

    Andersen, Steven Arild Wuyts; Konge, Lars; Sørensen, Mads Sølvsten

    2018-05-07

    Complex tasks such as surgical procedures can induce excessive cognitive load (CL), which can have a negative effect on learning, especially for novices. To investigate if repeated and distributed virtual reality (VR) simulation practice induces a lower CL and higher performance in subsequent cadaveric dissection training. In a prospective, controlled cohort study, 37 residents in otorhinolaryngology received VR simulation training either as additional distributed practice prior to course participation (intervention) (9 participants) or as standard practice during the course (control) (28 participants). Cognitive load was estimated as the relative change in secondary-task reaction time during VR simulation and cadaveric procedures. Structured distributed VR simulation practice resulted in lower mean reaction times (32% vs. 47% for the intervention and control group, respectively, p training. Repeated and distributed VR simulation causes a lower CL to be induced when the learning situation is increased in complexity. A suggested mechanism is the formation of mental schemas and reduction of the intrinsic CL. This has potential implications for surgical skills training and suggests that structured, distributed training be systematically implemented in surgical training curricula.

  15. Validity of Cognitive Load Measures in Simulation-Based Training: A Systematic Review.

    Science.gov (United States)

    Naismith, Laura M; Cavalcanti, Rodrigo B

    2015-11-01

    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.

  16. Time Accurate Unsteady Pressure Loads Simulated for the Space Launch System at a Wind Tunnel Condition

    Science.gov (United States)

    Alter, Stephen J.; Brauckmann, Gregory J.; Kleb, Bil; Streett, Craig L; Glass, Christopher E.; Schuster, David M.

    2015-01-01

    Using the Fully Unstructured Three-Dimensional (FUN3D) computational fluid dynamics code, an unsteady, time-accurate flow field about a Space Launch System configuration was simulated at a transonic wind tunnel condition (Mach = 0.9). Delayed detached eddy simulation combined with Reynolds Averaged Naiver-Stokes and a Spallart-Almaras turbulence model were employed for the simulation. Second order accurate time evolution scheme was used to simulate the flow field, with a minimum of 0.2 seconds of simulated time to as much as 1.4 seconds. Data was collected at 480 pressure taps at locations, 139 of which matched a 3% wind tunnel model, tested in the Transonic Dynamic Tunnel (TDT) facility at NASA Langley Research Center. Comparisons between computation and experiment showed agreement within 5% in terms of location for peak RMS levels, and 20% for frequency and magnitude of power spectral densities. Grid resolution and time step sensitivity studies were performed to identify methods for improved accuracy comparisons to wind tunnel data. With limited computational resources, accurate trends for reduced vibratory loads on the vehicle were observed. Exploratory methods such as determining minimized computed errors based on CFL number and sub-iterations, as well as evaluating frequency content of the unsteady pressures and evaluation of oscillatory shock structures were used in this study to enhance computational efficiency and solution accuracy. These techniques enabled development of a set of best practices, for the evaluation of future flight vehicle designs in terms of vibratory loads.

  17. Numerical simulation of deformation and failure processes of a complex technical object under impact loading

    Science.gov (United States)

    Kraus, E. I.; Shabalin, I. I.; Shabalin, T. I.

    2018-04-01

    The main points of development of numerical tools for simulation of deformation and failure of complex technical objects under nonstationary conditions of extreme loading are presented. The possibility of extending the dynamic method for construction of difference grids to the 3D case is shown. A 3D realization of discrete-continuum approach to the deformation and failure of complex technical objects is carried out. The efficiency of the existing software package for 3D modelling is shown.

  18. Computer simulation of model cohesive powders: Plastic consolidation, structural changes and elasticity under isotropic loads

    OpenAIRE

    Gilabert, Francisco; Roux, Jean-Noël; Castellanos, Antonio

    2008-01-01

    International audience; The quasistatic behavior of a simple 2D model of a cohesive powder under isotropic loads is investigated by Discrete Element simulations. The loose packing states, as studied in a previous paper, undergo important structural changes under growing confining pressure P, while solid fraction \\Phi irreversibly increases by large amounts. The system state goes through three stages, with different forms of the plastic consolidation curve \\Phi(P*), under growing reduced press...

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

    OpenAIRE

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

    2015-01-01

    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...

  20. Mechanical Properties of a Unidirectional Basalt-Fiber-Reinforced Plastic Under a Loading Simulating Operation Conditions

    Science.gov (United States)

    Lobanov, D. S.; Slovikov, S. V.

    2017-01-01

    The results of experimental investigations of unidirectional composites based on basalt fibers and different marks of epoxy resins are presented. Uniaxial tensile tests were carried out using a specimen fixation technique simulating the operation conditions of structures. The mechanical properties of the basalt-fiber-reinforced plastics (BFRPs) were determined. The diagrams of loading and deformation of BFRP specimens were obtain. The formulations of the composites with the highest mechanical properties were revealed.

  1. Critical current simulation in granular superconductors above the percolation threshold

    Science.gov (United States)

    Riedinger, Roland

    1992-02-01

    In the phase-coherent regime without applied external magnetic field, the critical superconducting current is limited by intragranular junctions which behave like Josephson junctions. We study the percolation aspects specific to lattices of such junctions and/or the mixing of superconductor with normal grains by averaging over configurations. We illustrate on 2 and 3 dimensional examples. The power laws valid near the percolation threshold are valid well above it, in two and three dimensions. We discuss the other models limiting the superconducting current, the vortex creep and superconducting order parameter fluctuations. Dans la limite de champ magnétique nul et de cohérence de phase du paramètre d'ordre supraconducteur, le courant supraconducteur maximal dans un réseau est limité par les jonctions intergranulaires qui se comportent comme des jonctions Josephson. Nous analysons les problèmes de percolation spécifiques aux réseaux de jonctions et du mélange de grains normaux et supraconducteurs. Nous donnons des exemples bidimensionnels et tridimensionnels ; après moyenne sur les configurations et analyse en taille finie, nous montrons que les lois de puissance valables au voisinage du seuil de percolation s'étendent sur un grand domaine au-delà du seuil de percolation, à deux et trois dimensions. Nous discutons les autres modèles limitant le courant supraconducteur, ancrage de vortex et fluctuations du paramètre d'ordre.

  2. Decision-Making in Critical Limb Ischemia: A Markov Simulation.

    Science.gov (United States)

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

    2017-11-01

    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.

  3. Numerical simulation of trans-critical carbon dioxide (R744) flow through short tube orifices

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Valladares, O. [Centro de Investigacion en Energia de la Universidad Nacional Autonoma de Mexico, Privada Xochicalco S/N, Apdo. Postal 34, 62580 Temixco, Morelos (Mexico)

    2006-02-01

    A detailed one-dimensional numerical simulation of the fluid-dynamic behaviour of short tube orifices expansion devices working with trans-critical carbon dioxide (CO{sub 2} or R744) has been developed. The discretized governing equations are coupled using an implicit step by step method. A special treatment has been implemented in order to consider transitions (subcooled liquid region and equilibrium two-phase region). The numerical model allows analysis of aspects such as geometry, different working conditions, critical or non-critical flow conditions, etc. Comparison of the numerical simulation with experimental data presented in the technical literature will be shown in the present article. (author)

  4. Molecular dynamics simulation of a binary mixture near the lower critical point

    Energy Technology Data Exchange (ETDEWEB)

    Pousaneh, Faezeh; Edholm, Olle, E-mail: oed@kth.se [Theoretical Biological Physics, Department of Theoretical Physics, Royal Institute of Technology (KTH), AlbaNova University Center, SE-106 91 Stockholm (Sweden); Maciołek, Anna [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland); Max-Planck-Institut für Intelligente Systeme, Heisenbergstrasse 3, D-70569 Stuttgart (Germany)

    2016-07-07

    2,6-lutidine molecules mix with water at high and low temperatures but in a wide intermediate temperature range a 2,6-lutidine/water mixture exhibits a miscibility gap. We constructed and validated an atomistic model for 2,6-lutidine and performed molecular dynamics simulations of 2,6-lutidine/water mixture at different temperatures. We determined the part of demixing curve with the lower critical point. The lower critical point extracted from our data is located close to the experimental one. The estimates for critical exponents obtained from our simulations are in a good agreement with the values corresponding to the 3D Ising universality class.

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

    Directory of Open Access Journals (Sweden)

    V. S. Grishin

    2016-01-01

    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.

  6. Argos: Residential end-use simulation model for load management strategy analysis

    International Nuclear Information System (INIS)

    Capasso, A.; Lamedica, R.; Prudenzi, A.

    1992-01-01

    In recent years, load management (LM) strategies, aimed at the optimization of available energy resources, as well as, the reduction of investments for new power plants, have been applied worldwide in residential end-use assessments. However, the forecasting of LM strategy impacts on the residential sector is very complex because it is based on a preliminary evaluation of the customers' proclivity to adapt their load characteristics to utility aims. In order to reduce load analysis requirements, which are substantial due to the need for thorough statistical analyses, complex field tests and measurements, the availability of models taking into account customer behavioural aspects is of paramount importance. This paper illustrates a simulation model which allows the performance of numerical evaluations concerning the effectiveness of some LM strategies applied to a residential end-use area load profile as previously determined by the aggregation of the contributions of individual households. This model enabled the evaluation of the impact, on the load profile, of a time-of-day tariff such as that recently introduced in Italy

  7. Cognitive load in distributed and massed practice in virtual reality mastoidectomy simulation.

    Science.gov (United States)

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

    2016-02-01

    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.

  8. Cognitive Load in Mastoidectomy Skills Training: Virtual Reality Simulation and Traditional Dissection Compared.

    Science.gov (United States)

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

    2016-01-01

    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.

  9. Simulation experience enhances physical therapist student confidence in managing a patient in the critical care environment.

    Science.gov (United States)

    Ohtake, Patricia J; Lazarus, Marcilene; Schillo, Rebecca; Rosen, Michael

    2013-02-01

    Rehabilitation of patients in critical care environments improves functional outcomes. This finding has led to increased implementation of intensive care unit (ICU) rehabilitation programs, including early mobility, and an associated increased demand for physical therapists practicing in ICUs. Unfortunately, many physical therapists report being inadequately prepared to work in this high-risk environment. Simulation provides focused, deliberate practice in safe, controlled learning environments and may be a method to initiate academic preparation of physical therapists for ICU practice. The purpose of this study was to examine the effect of participation in simulation-based management of a patient with critical illness in an ICU setting on levels of confidence and satisfaction in physical therapist students. A one-group, pretest-posttest, quasi-experimental design was used. Physical therapist students (N=43) participated in a critical care simulation experience requiring technical (assessing bed mobility and pulmonary status), behavioral (patient and interprofessional communication), and cognitive (recognizing a patient status change and initiating appropriate responses) skill performance. Student confidence and satisfaction were surveyed before and after the simulation experience. Students' confidence in their technical, behavioral, and cognitive skill performance increased from "somewhat confident" to "confident" following the critical care simulation experience. Student satisfaction was highly positive, with strong agreement the simulation experience was valuable, reinforced course content, and was a useful educational tool. Limitations of the study were the small sample from one university and a control group was not included. Incorporating a simulated, interprofessional critical care experience into a required clinical course improved physical therapist student confidence in technical, behavioral, and cognitive performance measures and was associated with high

  10. Insights and issues with simulating terrestrial DOC loading of Arctic river networks.

    Science.gov (United States)

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

    2013-12-01

    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.

  11. Insights and issues with simulating terrestrial DOC loading of Arctic river networks

    Science.gov (United States)

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

    2013-01-01

    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.

  12. Dynamic load synthesis for shock numerical simulation in space structure design

    Science.gov (United States)

    Monti, Riccardo; Gasbarri, Paolo

    2017-08-01

    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.

  13. Reproducibility of the Internal Load and Performance-Based Responses to Simulated Amateur Boxing.

    Science.gov (United States)

    Thomson, Edward D; Lamb, Kevin L

    2017-12-01

    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.

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

    International Nuclear Information System (INIS)

    Sepehrinia, Kazem; Mohammadi, Aliasghar

    2016-01-01

    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.

  15. 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: amohammadi@sharif.edu

    2016-05-15

    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.

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

    Directory of Open Access Journals (Sweden)

    Mohamed Badr

    2017-03-01

    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.

  17. Event-based scenario manager for multibody dynamics simulation of heavy load lifting operations in shipyards

    Directory of Open Access Journals (Sweden)

    Sol Ha

    2016-01-01

    Full Text Available This paper suggests an event-based scenario manager capable of creating and editing a scenario for shipbuilding process simulation based on multibody dynamics. To configure various situation in shipyards and easily connect with multibody dynamics, the proposed method has two main concepts: an Actor and an Action List. The Actor represents the anatomic unit of action in the multibody dynamics and can be connected to a specific component of the dynamics kernel such as the body and joint. The user can make a scenario up by combining the actors. The Action List contains information for arranging and executing the actors. Since the shipbuilding process is a kind of event-based sequence, all simulation models were configured using Discrete EVent System Specification (DEVS formalism. The proposed method was applied to simulations of various operations in shipyards such as lifting and erection of a block and heavy load lifting operation using multiple cranes.

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

    International Nuclear Information System (INIS)

    Wang, Haitao; Han, En-Hou

    2017-01-01

    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.

  19. 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)

    2017-04-15

    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.

  20. Simulation, Experimental and Analitical Study of Deflection at End Curved Beam Affected by Single Concentrated Load

    Directory of Open Access Journals (Sweden)

    Dewa Ngakan Ketut Putra Negara

    2012-11-01

    Full Text Available Deflection has an important role in order to design structure or machine component, beside consideration of stresscalculation. This is due to although stress is still smaller then stress allowed by material strength, but probably happen thatdeflection exceeds limit allowed. That condition affects serious hazard on machine elements or structure due to it can affectof component deviate from its main function. One of element which is often experience of deflection is beam. Beams playsignificant roles in many engineering applications, including buildings, bridges, automobiles, and airplane structures. In thisresearch, material to be used was Steel ASTM 1060, with specimen in the form of curved beam. Physical condition of beamwas modeled use of BEAM3 2D. Variation of loads to be applied were W = 100, 150, 200, 250, 300, 350, 400, 450, 500, and550 gr in vertical direction. The result of simulation was verificated by analytical and experimental data. Evaluation wascarried out by statistical test (t-test. The result of simulation is categorized to be good if the result of simulation is samewith analytical and experimental data. The result of research shows that loading has a significant effect on the deflection.The higher load affect the higher of deflection Modeling use of BEAM3 2D gave good result of deflection. This is showedfrom t-test have done, where the result of simulation was same with analytical and experimental data. Other advantage ofsimulation was deflection result obtained was not limited only at the end of beam, but it can predict of deflection at eachnode or point desired

  1. Repeated scenario simulation to improve competency in critical care: a new approach for nursing education.

    Science.gov (United States)

    Abe, Yukie; Kawahara, Chikako; Yamashina, Akira; Tsuboi, Ryoji

    2013-01-01

    In Japan, nursing education is being reformed to improve nurses' competency. Interest in use of simulation-based education to increase nurses' competency is increasing. To examine the effectiveness of simulation-based education in improving competency of cardiovascular critical care nurses. A training program that consisted of lectures, training in cardiovascular procedures, and scenario simulations was conducted with 24 Japanese nurses working at a university hospital. Participants were allocated to 4 groups, each of which visited 4 zones and underwent scenario simulations that included debriefings during and after the simulations. In each zone, the scenario simulation was repeated and participants assessed their own technical skills by scoring their performance on a rubric. Before and after the simulations, participants also completed a survey that used the Teamwork Activity Inventory in Nursing Scale (TAINS) to assess their nontechnical skills. All the groups showed increased rubric scores after the second simulation compared with the rubric scores obtained after the first simulation, despite differences in the order in which the scenarios were presented. Furthermore, the survey revealed significant increases in scores on the teamwork scale for the following subscale items: "Attitudes of the superior" (P Job satisfaction" (P = .01), and "Confidence as a team member" (P = .004). Our new educational approach of using repeated scenario simulations and TAINS seemed not only to enhance individual nurses' technical skills in critical care nursing but also to improve their nontechnical skills somewhat.

  2. Surface deterioration of dental materials after simulated toothbrushing in relation to brushing time and load.

    Science.gov (United States)

    Heintze, S D; Forjanic, M; Ohmiti, K; Rousson, V

    2010-04-01

    (1) To evaluate the changes in surface roughness and gloss after simulated toothbrushing of 9 composite materials and 2 ceramic materials in relation to brushing time and load in vitro; (2) to assess the relationship between surface gloss and surface roughness. Eight flat specimens of composite materials (microfilled: Adoro, Filtek Supreme, Heliomolar; microhybrid: Four Seasons, Tetric EvoCeram; hybrid: Compoglass F, Targis, Tetric Ceram; macrohybrid: Grandio), two ceramic materials (IPS d.SIGN and IPS Empress polished) were fabricated according to the manufacturer's instructions and optimally polished with up to 4000 grit SiC. The specimens were subjected to a toothbrushing (TB) simulation device (Willytec) with rotating movements, toothpaste slurry and at three different loads (100g/250g/350g). At hourly intervals from 1h to 10h TB, mean surface roughness Ra was measured with an optical sensor and the surface gloss (Gl) with a glossmeter. Statistical analysis was performed for log-transformed Ra data applying two-way ANOVA to evaluate the interaction between load and material and load and brushing time. There was a significant interaction between material and load as well as between load and brushing time (pgloss was the parameter which discriminated best between the materials, followed by mean surface roughness Ra. There was a strong correlation between surface gloss and surface roughness for all the materials except the ceramics. The evaluation of the deterioration curves of individual specimens revealed a more or less synchronous course suspecting hinting specific external conditions and not showing the true variability in relation to the tested material. The surface roughness and gloss of dental materials changes with brushing time and load and thus results in different material rankings. Apart from Grandio, the hybrid composite resins were more prone to surface changes than microfilled composites. The deterioration potential of a composite material can be

  3. Proper Generalized Decomposition (PGD) for the numerical simulation of polycrystalline aggregates under cyclic loading

    Science.gov (United States)

    Nasri, Mohamed Aziz; Robert, Camille; Ammar, Amine; El Arem, Saber; Morel, Franck

    2018-02-01

    The numerical modelling of the behaviour of materials at the microstructural scale has been greatly developed over the last two decades. Unfortunately, conventional resolution methods cannot simulate polycrystalline aggregates beyond tens of loading cycles, and they do not remain quantitative due to the plasticity behaviour. This work presents the development of a numerical solver for the resolution of the Finite Element modelling of polycrystalline aggregates subjected to cyclic mechanical loading. The method is based on two concepts. The first one consists in maintaining a constant stiffness matrix. The second uses a time/space model reduction method. In order to analyse the applicability and the performance of the use of a space-time separated representation, the simulations are carried out on a three-dimensional polycrystalline aggregate under cyclic loading. Different numbers of elements per grain and two time increments per cycle are investigated. The results show a significant CPU time saving while maintaining good precision. Moreover, increasing the number of elements and the number of time increments per cycle, the model reduction method is faster than the standard solver.

  4. Predictive Simulations of Neuromuscular Coordination and Joint-Contact Loading in Human Gait.

    Science.gov (United States)

    Lin, Yi-Chung; Walter, Jonathan P; Pandy, Marcus G

    2018-04-18

    We implemented direct collocation on a full-body neuromusculoskeletal model to calculate muscle forces, ground reaction forces and knee contact loading simultaneously for one cycle of human gait. A data-tracking collocation problem was solved for walking at the normal speed to establish the practicality of incorporating a 3D model of articular contact and a model of foot-ground interaction explicitly in a dynamic optimization simulation. The data-tracking solution then was used as an initial guess to solve predictive collocation problems, where novel patterns of movement were generated for walking at slow and fast speeds, independent of experimental data. The data-tracking solutions accurately reproduced joint motion, ground forces and knee contact loads measured for two total knee arthroplasty patients walking at their preferred speeds. RMS errors in joint kinematics were joint kinematics, ground forces, knee contact loads and muscle activation patterns measured for slow and fast walking. The results demonstrate the feasibility of performing computationally-efficient, predictive, dynamic optimization simulations of movement using full-body, muscle-actuated models with realistic representations of joint function.

  5. Examining the effects of microstructure and loading on the shock initiation of HMX with mesoscale simulations

    Science.gov (United States)

    Springer, H. Keo; Tarver, Craig; Bastea, Sorin

    2015-06-01

    We perform reactive mesoscale simulations to study shock initiation in HMX over a range of pore morphologies and sizes, porosities, and loading conditions in order to improve our understanding of structure-performance relationships. These relationships are important because they guide the development of advanced macroscale models incorporating hot spot mechanisms and the optimization of novel energetic material microstructures. Mesoscale simulations are performed using the multiphysics hydrocode, ALE3D. Spherical, elliptical, polygonal, and crack-like pore geometries 0.1, 1, 10, and 100 microns in size and 2, 5, 10, and 14% porosity are explored. Loading conditions are realized with shock pressures of 6, 10, 20, 38, and 50 GPa. A Cheetah-based tabular model, including temperature-dependent heat capacity, is used for the unreacted and the product equation-of-state. Also, in-line Cheetah is used to probe chemical species evolution. The influence of microstructure and shock loading on shock-to-detonation-transition run distance, reaction rate and product gas species evolution are discussed. This work performed under the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344. This work is funded by the Joint DoD-DOE Munitions Program.

  6. Real-time simulation of aeroelastic rotor loads for horizontal axis wind turbines

    International Nuclear Information System (INIS)

    Marnett, M; Wellenberg, S; Schröder, W

    2014-01-01

    Wind turbine drivetrain research and test facilities with hardware-in-the-loop capabilities require a robust and accurate aeroelastic real-time rotor simulation environment. Recent simulation environments do not guarantee a computational response at real-time. Which is why a novel simulation tool has been developed. It resolves the physical time domain of the turbulent wind spectra and the operational response of the turbine at real-time conditions. Therefore, there is a trade-off between accuracy of the physical models and the computational costs. However, the study shows the possibility to preserve the necessary computational accuracy while simultaneously granting dynamic interaction with the aeroelastic rotor simulation environment. The achieved computational costs allow a complete aeroelastic rotor simulation at a resolution frequency of 100 Hz on standard computer platforms. Results obtained for the 5-MW reference wind turbine by the National Renewable Energy Laboratory (NREL) are discussed and compared to NREL's fatigue, aerodynamics, structures, and turbulence (FAST)- Code. The rotor loads show a convincing match. The novel simulation tool is applied to the wind turbine drivetrain test facility at the Center for Wind Power Drives (CWD), RWTH Aachen University to show the real-time hardware-in-the-loop capabilities

  7. Numerical simulation of the shot peening process under previous loading conditions

    International Nuclear Information System (INIS)

    Romero-Ángeles, B; Urriolagoitia-Sosa, G; Torres-San Miguel, C R; Molina-Ballinas, A; Benítez-García, H A; Vargas-Bustos, J A; Urriolagoitia-Calderón, G

    2015-01-01

    This research presents a numerical simulation of the shot peening process and determines the residual stress field induced into a component with a previous loading history. The importance of this analysis is based on the fact that mechanical elements under shot peening are also subjected to manufacturing processes, which convert raw material into finished product. However, material is not provided in a virgin state, it has a previous loading history caused by the manner it is fabricated. This condition could alter some beneficial aspects of the residual stress induced by shot peening and could accelerate the crack nucleation and propagation progression. Studies were performed in beams subjected to strain hardening in tension (5ε y ) before shot peening was applied. Latter results were then compared in a numerical assessment of an induced residual stress field by shot peening carried out in a component (beam) without any previous loading history. In this paper, it is clearly shown the detrimental or beneficial effect that previous loading history can bring to the mechanical component and how it can be controlled to improve the mechanical behavior of the material

  8. The Effect of Learning Styles, Critical Thinking Disposition, and Critical Thinking on Clinical Judgment in Senior Baccalaureate Nursing Students during Human Patient Simulation

    Science.gov (United States)

    McCormick, Kiyan

    2014-01-01

    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…

  9. Repetitive plasma loads typical for ITER Type-I ELMS; simulation in QSPA Kh-50

    International Nuclear Information System (INIS)

    Tereshin, V.I.; Bandura, A.N.; Byrka, O.V.; Chebotarev, V.V.; Garkusha, I.E.; Makhlaj, V.A.; Solyakov, D.G.; Tsarenko, A.V.; Landman, I.

    2005-01-01

    The power loads on current tokamaks associated with the Type I ELMs generally do not affect the lifetime of divertor elements. However, the ITER ELMs may lead to unacceptable lifetime; their loads are estimated as QELM(1-3) MJ/m 2 at t = 0.1-1 ms and the repetition frequency of an order of 1 Hz (∼ 400 ELMs during each ITER pulse). Such plasma energy loads expected for ITER ELMs are not achieved in existing tokamaks. Therefore powerful plasma accelerators are used at present for study of plasma-target interaction and for numerical models validation. Quasi-steady-state plasma accelerators (QSPA), which characterized by essentially longer duration of plasma stream generation in comparison with pulsed plasma guns, became especially attractive facilities for investigations of plasma-surface interaction in conditions of high heat loads simulating the ITER disruptions and ELMs. The paper presents experimental study of energy characteristics of the plasma streams generated with quasi-steady-state plasma accelerator QSPA Kh-50 and the main features of plasma interaction with material surfaces in dependence on plasma heat loads. The samples of pure sintered tungsten of EU trademark have been exposed to hydrogen plasma streams produced by the accelerator. To estimate the range of tolerable loads the effects of ELMs on the lifetime of plasma facing components have been experimentally simulated for large numbers of impacts with varying energy density. The experiments were performed with up to 450 pulses of the duration of 0.25 ms and the heat loads in the range of 0.5 - 1.2 MJ/m 2 . At this calorimetry (both at plasma stream and at the target surface), piezo-detectors as well as spectroscopy and interferometry measurements were applied to determine the impacting plasma parameters in different regimes of operation. A threshold character of morphological changes on the tungsten surface under the melting in respect to the pulses number is demonstrated. The number of initial

  10. Completion of UO2 pellets production and fuel rods load for the RA-8 critical facility

    International Nuclear Information System (INIS)

    Marajofsky, Adolfo; Perez, Lidia E.; Thern, Gerardo G.; Altamirano, Jorge S.; Benitez, Ana M.; Cardenas, Hugo R.; Becerra, Fabian A.; Perez, Aldo E.; Fuente, Mariano de la

    1999-01-01

    The Advanced Fuels Division produced fuel pellets of 235 U with 1.8% and 3.6% enrichment and Zry-4 cladding loads for the RA-8 reactor at Pilcaniyeu Technological Unit. For economical and availability reasons, the powder acquired was initially UO 2 with 3.4% enrichment in 235 U, therefore the 235 U powder with 1.8% enrichment was produced by mechanical mixture. The production of fuel pellets for both enrichments was carried out by cold pressing and sintering processes in reducing atmosphere. The load of Zry-4 claddings was performed manually. The production stages can be divided into setup, qualification and production. This production allows not only to fulfill satisfactorily the new fuel rods supply for the RA-8 reactor but also to count with a new equipment and skilled personnel as well as to meet quality and assurance control methods for future pilot-scale production and even new fuel elements production. (author)

  11. Erosion simulation of first wall beryllium armour after ITER transient heat loads and runaway electrons action

    Energy Technology Data Exchange (ETDEWEB)

    Bazylev, B., E-mail: boris.bazylev@kit.edu [Karlsruhe Institute of Technology, IHM, P.O. Box 3640, D-76021 Karlsruhe (Germany); Igitkhanov, Yu.; Landman, I.; Pestchanyi, S. [Karlsruhe Institute of Technology, IHM, P.O. Box 3640, D-76021 Karlsruhe (Germany); Loarte, A. [ITER Organisation, Cadarache, 13108 Saint Paul Lez Durance Cedex (France)

    2011-10-01

    Beryllium is foreseen as plasma facing armour for the first wall (FW) in 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) and runaway electrons impact 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, evaporation, and melt motion, which determine the life-time of the plasma facing components. The melt motion damages of Be macrobrush armour caused by the tangential friction force and the J x B forces are analyzed for bulk Be and different sizes of Be-brushes. The damage of the FW due to heat loads caused by runaway electrons is numerically simulated.

  12. Erosion simulation of first wall beryllium armour after ITER transient heat loads and runaway electrons action

    International Nuclear Information System (INIS)

    Bazylev, B.; Igitkhanov, Yu.; Landman, I.; Pestchanyi, S.; Loarte, A.

    2011-01-01

    Beryllium is foreseen as plasma facing armour for the first wall (FW) in 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) and runaway electrons impact 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, evaporation, and melt motion, which determine the life-time of the plasma facing components. The melt motion damages of Be macrobrush armour caused by the tangential friction force and the J x B forces are analyzed for bulk Be and different sizes of Be-brushes. The damage of the FW due to heat loads caused by runaway electrons is numerically simulated.

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

    DEFF Research Database (Denmark)

    Juul, Jonas; Paltved, Charlotte; Krogh, Kristian

    2014-01-01

    for content analysis4 and thematic analysis5. Medical experts and simulation faculty will design scenarios for in situ simulation training based on the analysis. Short-term observations using time logs will be performed along with interviews with key informants at the departments. Video data will be collected...... improve patient safety if coupled with training and organisational support2. Insight into the nature of reported critical incidents and adverse events can be used in writing in situ simulation scenarios and thus lead to interventions that enhance patient safety. The patient safety literature emphasises...... well-developed non-technical skills in preventing medical errors3. Furthermore, critical incidents and adverse events reporting systems comprise a knowledgebase to gain in-depth insights into patient safety issues. This study explores the use of critical incidents and adverse events reports to inform...

  14. Test methods and load simulation at roller test stand; Pruefmethoden und Lastsimulation auf Rollenpruefstaenden

    Energy Technology Data Exchange (ETDEWEB)

    Engelmann, Juergen [BMW AG, Muenchen (Germany); Koenig, Manfred [VISPIRON AG, Muenchen (Germany)

    2012-11-01

    The development of vehicles is a time expensive process and requires a worldwide mobility, since the vehicles are tested for different environmental conditions, which only occur in specified regions and within predefined seasonal periods. To become independent of weather conditions and the local and seasonal variation, it is necessary to shift particular tests to a climatic wind tunnel. Although this offers an ideal environment for precise and reproducible results, many tests need to be performed in order to acquire knowledge about the differences between real road investigations and wind tunnel experiments. It is the work of Method developers to properly transfer specified road tests to the test facility such that comparable results are obtained. These details will be discussed in the first chapter. An important aspect, within this objective, is the realistic simulation of drive resistance on the road by dynamometers. Therefore the different forces, contributing to the drive resistance on the road, are determined in order to simulate the realistic load on the vehicle drive train by the electric drive units of the dynamometers. To increase the accuracy of the load simulation, a special feature has been added to the dyno-control. This feature includes the influence of air-density on the drive resistance at a given environmental temperature, pressure and humidity. (orig.)

  15. Fluid-structure interaction dynamic simulation of spring-loaded pressure relief valves under seismic wave

    Science.gov (United States)

    Lv, Dongwei; Zhang, Jian; Yu, Xinhai

    2018-05-01

    In this paper, a fluid-structure interaction dynamic simulation method of spring-loaded pressure relief valve was established. The dynamic performances of the fluid regions and the stress and strain of the structure regions were calculated at the same time by accurately setting up the contact pairs between the solid parts and the coupling surfaces between the fluid regions and the structure regions. A two way fluid-structure interaction dynamic simulation of a simplified pressure relief valve model was carried out. The influence of vertical sinusoidal seismic waves on the performance of the pressure relief valve was preliminarily investigated by loading sine waves. Under vertical seismic waves, the pressure relief valve will flutter, and the reseating pressure was affected by the amplitude and frequency of the seismic waves. This simulation method of the pressure relief valve under vertical seismic waves can provide effective means for investigating the seismic performances of the valves, and make up for the shortcomings of the experiment.

  16. Numerical Simulation of Hysteretic Live Load Effect in a Soil-Steel Bridge

    Directory of Open Access Journals (Sweden)

    Sobótka Maciej

    2014-03-01

    Full Text Available The paper presents numerical simulation of hysteretic live load effect in a soil-steel bridge. The effect was originally identified experimentally by Machelski [1], [2]. The truck was crossing the bridge one way and the other in the full-scale test performed. At the same time, displacements and stress in the shell were measured. The major conclusion from the research was that the measured quantities formed hysteretic loops. A numerical simulation of that effect is addressed in the present work. The analysis was performed using Flac finite difference code. The methodology of solving the mechanical problems implemented in Flac enables us to solve the problem concerning a sequence of load and non-linear mechanical behaviour of the structure. The numerical model incorporates linear elastic constitutive relations for the soil backfill, for the steel shell and the sheet piles, being a flexible substructure for the shell. Contact zone between the shell and the soil backfill is assumed to reflect elastic-plastic constitutive model. Maximum shear stress in contact zone is limited by the Coulomb condition. The plastic flow rule is described by dilation angle ψ = 0. The obtained results of numerical analysis are in fair agreement with the experimental evidence. The primary finding from the performed simulation is that the slip in the interface can be considered an explanation of the hysteresis occurrence in the charts of displacement and stress in the shell.

  17. Heavy vehicle simulator (HVS) evaluation of load transfer efficiency and continuously reinforced concrete inlays on the N3 near Pietermartizburg

    CSIR Research Space (South Africa)

    Du Plessis, L

    2006-07-01

    Full Text Available The paper addresses two different heavy Vehicle Simulator (HVS) studies conducted on concrete: Load transfer through aggregate interlock and the use of dowels and the evaluation of the performance of an in-service continuously reinforced concrete...

  18. A hybrid load flow and event driven simulation approach to multi-state system reliability evaluation

    International Nuclear Information System (INIS)

    George-Williams, Hindolo; Patelli, Edoardo

    2016-01-01

    Structural complexity of systems, coupled with their multi-state characteristics, renders their reliability and availability evaluation difficult. Notwithstanding the emergence of various techniques dedicated to complex multi-state system analysis, simulation remains the only approach applicable to realistic systems. However, most simulation algorithms are either system specific or limited to simple systems since they require enumerating all possible system states, defining the cut-sets associated with each state and monitoring their occurrence. In addition to being extremely tedious for large complex systems, state enumeration and cut-set definition require a detailed understanding of the system's failure mechanism. In this paper, a simple and generally applicable simulation approach, enhanced for multi-state systems of any topology is presented. Here, each component is defined as a Semi-Markov stochastic process and via discrete-event simulation, the operation of the system is mimicked. The principles of flow conservation are invoked to determine flow across the system for every performance level change of its components using the interior-point algorithm. This eliminates the need for cut-set definition and overcomes the limitations of existing techniques. The methodology can also be exploited to account for effects of transmission efficiency and loading restrictions of components on system reliability and performance. The principles and algorithms developed are applied to two numerical examples to demonstrate their applicability. - Highlights: • A discrete event simulation model based on load flow principles. • Model does not require system path or cut sets. • Applicable to binary and multi-state systems of any topology. • Supports multiple output systems with competing demand. • Model is intuitive and generally applicable.

  19. Measuring Cognitive Load during Simulation-Based Psychomotor Skills Training: Sensitivity of Secondary-Task Performance and Subjective Ratings

    Science.gov (United States)

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

    2015-01-01

    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…

  20. Modeling and Simulation in the Army Intermediate Level Education Critical Thinking Curriculum

    Science.gov (United States)

    2015-06-12

    and bring me back to reality when I become too technical. These characteristics also apply to the MMAS board that guided me in researching this paper...curriculum 1 ProCon.org, “Critical Thinking Quote: Adrienne Rich ,” last updated August 8, 2013...ray-odierno/. 5 embraced visual learning to teach the millennial generation, to include using simulations to enhance understanding of critical

  1. Assessing Critical Thinking Outcomes of Dental Hygiene Students Utilizing Virtual Patient Simulation: A Mixed Methods Study.

    Science.gov (United States)

    Allaire, Joanna L

    2015-09-01

    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.

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

    Directory of Open Access Journals (Sweden)

    S. Pestchanyi

    2016-12-01

    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.

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

    DEFF Research Database (Denmark)

    2014-01-01

    , 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......, and is not easy to use nor easy installable. During the course of 2015 a library will be released with proper build, install and usage documentation. The version that is included in this repository was extensively used within the INDUFLAP project....

  4. The effect of human patient simulation on critical thinking and its predictors in prelicensure nursing students.

    Science.gov (United States)

    Shinnick, Mary Ann; Woo, Mary A

    2013-09-01

    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.

  5. A critical pressure based panel method for prediction of unsteady loading of marine propellers under cavitation

    International Nuclear Information System (INIS)

    Liu, P.; Bose, N.; Colbourne, B.

    2002-01-01

    A simple numerical procedure is established and implemented into a time domain panel method to predict hydrodynamic performance of marine propellers with sheet cavitation. This paper describes the numerical formulations and procedures to construct this integration. Predicted hydrodynamic loads were compared with both a previous numerical model and experimental measurements for a propeller in steady flow. The current method gives a substantial improvement in thrust and torque coefficient prediction over a previous numerical method at low cavitation numbers of less than 2.0, where severe cavitation occurs. Predicted pressure coefficient distributions are also presented. (author)

  6. Critical and subcritical parameters of the system simulating plutonium metal dissolution

    International Nuclear Information System (INIS)

    Vasilev, Yury Yu.; Ryazanov, Boris G.; Sviridov, Victor I.; Mozhayeva, Lubov I.

    2003-01-01

    Dissolution of plutonium metal was simulated using the Monte Carlo computer code to calculate criticality safety limits for the process. Calculations were made for the constant masses of plutonium charged to the dissolving vessel considering distribution of plutonium in metal and solution phases. Critical parameters and limits were calculated as a function of dissolving vessel volume and plutonium metal mass. 240 Pu content was assumed to be from 0% to 10% (mass). Critical parameters were evaluated for the system with a water reflector. Results of this paper may be used in the designing process equipment for plutonium metal dissolution. (author)

  7. Load management strategy for Particle-In-Cell simulations in high energy particle acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Beck, A., E-mail: beck@llr.in2p3.fr [Laboratoire Leprince-Ringuet, École polytechnique, CNRS-IN2P3, Palaiseau 91128 (France); Frederiksen, J.T. [Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 København Ø (Denmark); Dérouillat, J. [CEA, Maison de La Simulation, 91400 Saclay (France)

    2016-09-01

    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. In this paper, we compare the results given by different codes and point out algorithmic limitations both in terms of physical accuracy and computational performances. These limitations are illustrated in the context of electron laser wakefield acceleration (LWFA). The main limitation we identify in state-of-the-art Particle-In-Cell (PIC) codes is computational load imbalance. We propose an innovative algorithm to deal with this specific issue as well as milestones towards a modern, accurate high-performance PIC code for high energy particle acceleration.

  8. Numerical Simulation of Wave Propagation and Phase Transition of Tin under Shock-Wave Loading

    International Nuclear Information System (INIS)

    Hai-Feng, Song; Hai-Feng, Liu; Guang-Cai, Zhang; Yan-Hong, Zhao

    2009-01-01

    We undertake a numerical simulation of shock experiments on tin reported in the literature, by using a multiphase equation of state (MEOS) and a multiphase Steinberg Guinan (MSG) constitutive model for tin in the β, γ and liquid phases. In the MSG model, the Bauschinger effect is considered to better describe the unloading behavior. The phase diagram and Hugoniot of tin are calculated by MEOS, and they agree well with the experimental data. Combined with the MEOS and MSG models, hydrodynamic computer simulations are successful in reproducing the measured velocity profile of the shock wave experiment. Moreover, by analyzing the mass fraction contour as well as stress and temperature profiles of each phase for tin, we further discuss the complex behavior of tin under shock-wave loading. (condensed matter: structure, mechanical and thermal properties)

  9. Fatigue mechanisms in an austenitic steel under cyclic loading: Experiments and atomistic simulations

    Energy Technology Data Exchange (ETDEWEB)

    Soppa, E.A., E-mail: ewa.soppa@mpa.uni-stuttgart.de; Kohler, C., E-mail: christopher.kohler@mpa.uni-stuttgart.de; Roos, E., E-mail: eberhard.roos@mpa.uni-stuttgart.de

    2014-03-01

    Experimental investigations on the austenitic stainless steel X6CrNiNb18-10 (AISI – 347) and concomitant atomistic simulations of a FeNi nanocrystalline model system have been performed in order to understand the basic mechanisms of fatigue damage under cyclic loading. Using electron backscatter diffraction (EBSD) the influence of deformation induced martensitic transformation and NbC size distribution on the fatigue crack formation has been demonstrated. The martensite nucleates prevalently at grain boundaries, triple points and at the specimen free surface and forms small (∼1 µm sized) differently oriented grains. The atomistic simulations show the role of regions of a high density of stacking faults for the martensitic transformation.

  10. Experiment and simulation study on unidirectional carbon fiber composite component under dynamic 3 point bending loading

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Guowei; Sun, Qingping; Zeng, Danielle; Li, Dayong; Su, Xuming

    2018-04-10

    In current work, unidirectional (UD) carbon fiber composite hatsection component with two different layups are studied under dynamic 3 point bending loading. The experiments are performed at various impact velocities, and the effects of impactor velocity and layup on acceleration histories are compared. A macro model is established with LS-Dyna for more detailed study. The simulation results show that the delamination plays an important role during dynamic 3 point bending test. Based on the analysis with high speed camera, the sidewall of hatsection shows significant buckling rather than failure. Without considering the delamination, current material model cannot capture the post failure phenomenon correctly. The sidewall delamination is modeled by assumption of larger failure strain together with slim parameters, and the simulation results of different impact velocities and layups match the experimental results reasonable well.

  11. Criticality safety study of dry spent fuel cask loaded with increased enrichment fuel

    International Nuclear Information System (INIS)

    Bznuni, S.; Baghdasaryan, N.; Amirjanyan, A.

    2013-01-01

    Existing Dry Spent Fuel Casks (DSC) for transporting and storing of Armenian NPP fuel was licensed for WWER-440 fuel assemblies with 3.6% enrichment. Having in mind that ANPP introduced new fuel assemblies with increased enrichment (3.82 %) re-assessment of criticality safety analysis for DSC is required. Criticality safety analysis of DSC was performed by KENO-VI program using 238-GROUP ENDF/B-VII.0 LIBRARY (V7-238). Results of analysis showed that additional 8 borated racks for fuel assemblies should be included in the design of DSC. In addition feasibility study was performed to find out level of burnup-credit approach implementation to keep current design of DSC unchanged. Burnup-credit analysis was performed by STARBUCS program using axial burnup profiles from Armenian NPP neutronics analysis carried out by BIPR code. (authors)

  12. Improvement of the skeleton tables for calculation of the critical heat load

    International Nuclear Information System (INIS)

    Gotovskij, M.A.; Kvetnyj, M.A.

    2002-01-01

    Paper presents analysis of drawbacks of the skeleton tables of the critical heat flows applied in calculated heat and hydraulic codes. Paper demonstrates the necessity to take account of specific nature of mechanisms of dryout crisis, of boiling crisis at slow mass rates and the range of small underheatings up to temperature of saturation. Attention is drawn to necessity of detailed account of the natural limitations of the application field of the skeleton tables [ru

  13. Critical Loads of Atmospheric Nitrogen Deposition for Aquatic Ecosystems in Yosemite and Sequoia and Kings Canyon National Parks

    Science.gov (United States)

    Nanus, L.; Clow, D. W.; Sickman, J. O.

    2016-12-01

    High-elevation aquatic ecosystems in Yosemite (YOSE) and Sequoia and Kings Canyon (SEKI) National Parks are impacted by atmospheric nitrogen (N) deposition associated with local and regional air pollution. Documented effects include elevated surface water nitrate concentrations, increased algal productivity, and changes in diatom species assemblages. Annual wet inorganic N deposition maps, developed at 1-km resolution for YOSE and SEKI to quantify N deposition to sensitive high-elevation ecosystems, range from 1.0 to over 5.0 kg N ha-1 yr-1. Critical loads of N deposition for nutrient enrichment of aquatic ecosystems were quantified and mapped using a geostatistical approach, with N deposition, topography, vegetation, geology, and climate as potential explanatory variables. Multiple predictive models were created using various combinations of explanatory variables; this approach allowed us to better quantify uncertainty and more accurately identify the areas most sensitive to atmospherically deposited N. The lowest critical loads estimates and highest exceedances identified within YOSE and SEKI occurred in high-elevation basins with steep slopes, sparse vegetation, and areas of neoglacial till and talus. These results are consistent with previous analyses in the Rocky Mountains, and highlight the sensitivity of alpine ecosystems to atmospheric N deposition.

  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

    2017-01-01

    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. Static Load Test on Instrumented Pile – Field Data and Numerical Simulations

    Directory of Open Access Journals (Sweden)

    Krasiński Adam

    2017-09-01

    Full Text Available Static load tests on foundation piles are generally carried out in order to determine load – the displacement characteristic of the pile head. For standard (basic engineering practices this type of test usually provides enough information. However, the knowledge of force distribution along the pile core and its division into the friction along the shaft and the resistance under the base can be very useful. Such information can be obtained by strain gage pile instrumentation [1]. Significant investigations have been completed on this technology, proving its utility and correctness [8], [10], [12]. The results of static tests on instrumented piles are not easy to interpret. There are many factors and processes affecting the final outcome. In order to understand better the whole testing process and soil-structure behavior some investigations and numerical analyses were done. In the paper, real data from a field load test on instrumented piles is discussed and compared with numerical simulation of such a test in similar conditions. Differences and difficulties in the results interpretation with their possible reasons are discussed. Moreover, the authors used their own analytical solution for more reliable determination of force distribution along the pile. The work was presented at the XVII French-Polish Colloquium of Soil and Rock Mechanics, Łódź, 28–30 November 2016.

  16. Static Load Test on Instrumented Pile - Field Data and Numerical Simulations

    Science.gov (United States)

    Krasiński, Adam; Wiszniewski, Mateusz

    2017-09-01

    Static load tests on foundation piles are generally carried out in order to determine load - the displacement characteristic of the pile head. For standard (basic) engineering practices this type of test usually provides enough information. However, the knowledge of force distribution along the pile core and its division into the friction along the shaft and the resistance under the base can be very useful. Such information can be obtained by strain gage pile instrumentation [1]. Significant investigations have been completed on this technology, proving its utility and correctness [8], [10], [12]. The results of static tests on instrumented piles are not easy to interpret. There are many factors and processes affecting the final outcome. In order to understand better the whole testing process and soil-structure behavior some investigations and numerical analyses were done. In the paper, real data from a field load test on instrumented piles is discussed and compared with numerical simulation of such a test in similar conditions. Differences and difficulties in the results interpretation with their possible reasons are discussed. Moreover, the authors used their own analytical solution for more reliable determination of force distribution along the pile. The work was presented at the XVII French-Polish Colloquium of Soil and Rock Mechanics, Łódź, 28-30 November 2016.

  17. Numerical Simulation and Validation of a High Head Model Francis Turbine at Part Load Operating Condition

    Science.gov (United States)

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

    2017-07-01

    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.

  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.

    2015-01-01

    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

    Science.gov (United States)

    Battaile, Corbett; Owen, Steven; Moore, Nathan

    2017-06-01

    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. Effects of Zoledronate and Mechanical Loading during Simulated Weightlessness on Bone Structure and Mechanical Properties

    Science.gov (United States)

    Scott, R. T.; Nalavadi, M. O.; Shirazi-Fard, Y.; Castillo, A. B.; Alwood, J. S.

    2016-01-01

    ZOL not modulating trabecular thickness in CL + NAHU mice. In summary, our integrated model simulates the combination of weightlessness, exercise-induced mechanical strain, and anti-resorptive treatment that astronauts experience during space missions. Based on these results, we conclude that, at the structural and stiffness level, zoledronate treatment during simulated spaceflight does not impede the skeletal response to axial compression. In contrast to our hypothesis, our data show that zoledronate confers no additional mechanical or structural benefit beyond those gained from cyclical loading.

  1. Vibration of Bridges under the Passage of Vehicles Simulated as Moving Loads

    International Nuclear Information System (INIS)

    Ouchenane, M.; Lassoued, R.; Ouchenane, K.

    2011-01-01

    The dynamic behavior of bridges under the effect of moving loads simulating the vehicle moving along the bridge structure idealized by an Euler beam is analyzed. We will present the dynamic behavior of beams under the stress of moving loads (or masses) by the analytical and semi-analytical approaches. When the mass of the bridge structure is comparable to that of the vehicle, the mobile source requesting the bridge is simulated by a mass. In most practical cases, the mobile force used is due to the effects of the gravitational moving masses: . When the moving mass is small compared to the beam mass, the obtained solution under the effect of moving force is approximately correct for the solution obtained with the moving mass. Otherwise, the problem of the moving mass is imperative. To do this, we wrote a program in Matlab language which reflects the dynamic behavior of beams under the effect of moving charges, which gives the following results T he frequencies and modes of vibration, the dynamics deflection of the beam requested by moving force, the dynamic response (DAF: dynamic amplification factor) of the beam requested by a moving force, over the whole length of the beam, for all times and for different speeds. The numerical example that we look to see for study the dynamic behavior of this type of bridge under moving loads is that of a thin beam unamortised on simple support and length of 50m, under the solicitation of moving force and mass at a constant speed and varies from 0 to 100 m / s (M. A. Foda, 1997), depending on the relationship between the vehicle mass and the mass of the bridge that will allow us to see the contribution of the choice of modelling type on the total response and then the vibration of bridge, also we will study the effect of type of simulation of the load by moving force or mass on the dynamic amplification factor and comparing our results with those from the literature. (author)

  2. Nonlinear adaptive robust back stepping force control of hydraulic load simulator: Theory and experiments

    International Nuclear Information System (INIS)

    Yao, Jianyong; Jiao, Zongxia; Yao, Bin

    2014-01-01

    High performance robust force control of hydraulic load simulator with constant but unknown hydraulic parameters is considered. In contrast to the linear control based on hydraulic linearization equations, hydraulic inherent nonlinear properties and uncertainties make the conventional feedback proportional-integral-derivative (PID) control not yield to high performance requirements. Furthermore, the hydraulic system may be subjected to non-smooth and discontinuous nonlinearities due to the directional change of valve opening. In this paper, based on a nonlinear system model of hydraulic load simulator, a discontinuous projection-based nonlinear adaptive robust back stepping controller is developed with servo valve dynamics. The proposed controller constructs a novel stable adaptive controller and adaptation laws with additional pressure dynamic related unknown parameters, which can compensate for the system nonlinearities and uncertain parameters, meanwhile a well-designed robust controller is also synthesized to dominate the model uncertainties coming from both parametric uncertainties and uncertain nonlinearities including unmodeled and ignored system dynamics. The controller theoretically guarantee a prescribed transient performance and final tracking accuracy in presence of both parametric uncertainties and uncertain nonlinearities; while achieving asymptotic output tracking in the absence of unstructured uncertainties. The implementation issues are also discussed for controller simplification. Some comparative results are obtained to verify the high-performance nature of the proposed controller.

  3. Nonlinear adaptive robust back stepping force control of hydraulic load simulator: Theory and experiments

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Jianyong [Nanjing University of Science and Technology, Nanjing (China); Jiao, Zongxia [Beihang University, Beijing (China); Yao, Bin [Purdue University, West Lafayette (United States)

    2014-04-15

    High performance robust force control of hydraulic load simulator with constant but unknown hydraulic parameters is considered. In contrast to the linear control based on hydraulic linearization equations, hydraulic inherent nonlinear properties and uncertainties make the conventional feedback proportional-integral-derivative (PID) control not yield to high performance requirements. Furthermore, the hydraulic system may be subjected to non-smooth and discontinuous nonlinearities due to the directional change of valve opening. In this paper, based on a nonlinear system model of hydraulic load simulator, a discontinuous projection-based nonlinear adaptive robust back stepping controller is developed with servo valve dynamics. The proposed controller constructs a novel stable adaptive controller and adaptation laws with additional pressure dynamic related unknown parameters, which can compensate for the system nonlinearities and uncertain parameters, meanwhile a well-designed robust controller is also synthesized to dominate the model uncertainties coming from both parametric uncertainties and uncertain nonlinearities including unmodeled and ignored system dynamics. The controller theoretically guarantee a prescribed transient performance and final tracking accuracy in presence of both parametric uncertainties and uncertain nonlinearities; while achieving asymptotic output tracking in the absence of unstructured uncertainties. The implementation issues are also discussed for controller simplification. Some comparative results are obtained to verify the high-performance nature of the proposed controller.

  4. Physics Simulation Software for Autonomous Propellant Loading and Gas House Autonomous System Monitoring

    Science.gov (United States)

    Regalado Reyes, Bjorn Constant

    2015-01-01

    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. Time-Accurate Unsteady Pressure Loads Simulated for the Space Launch System at Wind Tunnel Conditions

    Science.gov (United States)

    Alter, Stephen J.; Brauckmann, Gregory J.; Kleb, William L.; Glass, Christopher E.; Streett, Craig L.; Schuster, David M.

    2015-01-01

    A transonic flow field about a Space Launch System (SLS) configuration was simulated with the Fully Unstructured Three-Dimensional (FUN3D) computational fluid dynamics (CFD) code at wind tunnel conditions. Unsteady, time-accurate computations were performed using second-order Delayed Detached Eddy Simulation (DDES) for up to 1.5 physical seconds. The surface pressure time history was collected at 619 locations, 169 of which matched locations on a 2.5 percent wind tunnel model that was tested in the 11 ft. x 11 ft. test section of the NASA Ames Research Center's Unitary Plan Wind Tunnel. Comparisons between computation and experiment showed that the peak surface pressure RMS level occurs behind the forward attach hardware, and good agreement for frequency and power was obtained in this region. Computational domain, grid resolution, and time step sensitivity studies were performed. These included an investigation of pseudo-time sub-iteration convergence. Using these sensitivity studies and experimental data comparisons, a set of best practices to date have been established for FUN3D simulations for SLS launch vehicle analysis. To the author's knowledge, this is the first time DDES has been used in a systematic approach and establish simulation time needed, to analyze unsteady pressure loads on a space launch vehicle such as the NASA SLS.

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

    Directory of Open Access Journals (Sweden)

    Changbiao Wang

    2007-12-01

    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.

  7. 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

    2012-12-01

    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.

  8. Multilevel criticality computations in AREVA NP'S core simulation code artemis - 195

    International Nuclear Information System (INIS)

    Van Geemert, R.

    2010-01-01

    This paper discusses the multi-level critical boron iteration approach that is applied per default in AREVA NP's whole-core neutronics and thermal hydraulics core simulation program ARTEMIS. This multi-level approach is characterized by the projection of variational boron concentration adjustments to the coarser mesh levels in a multi-level re-balancing hierarchy that is associated with the nodal flux equations to be solved in steady-state core simulation. At each individual re-balancing mesh level, optimized variational criticality tuning formulas are applied. The latter drive the core model to a numerically highly accurate self-sustaining state (i.e. with the neutronic eigenvalue being 1 up to a very high numerical precision) by continuous adjustment of the boron concentration as a system-wide scalar criticality parameter. Due to the default application of this approach in ARTEMIS reactor cycle simulations, an accuracy of all critical boron concentration estimates better than 0.001 ppm is enabled for all burnup time steps in a computationally efficient way. This high accuracy is relevant for precision optimization in industrial core simulation as well as for enabling accurate reactivity perturbation assessments. The developed approach is presented from a numerical methodology point of view with an emphasis on the multi-grid aspect of the concept. Furthermore, an application-relevant verification is presented in terms of achieved coupled iteration convergence efficiency for an application-representative industrial core cycle computation. (authors)

  9. Feedback for Simulation-Based Procedural Skills Training: A Meta-Analysis and Critical Narrative Synthesis

    Science.gov (United States)

    Hatala, Rose; Cook, David A.; Zendejas, Benjamin; Hamstra, Stanley J.; Brydges, Ryan

    2014-01-01

    Although feedback has been identified as a key instructional feature in simulation based medical education (SBME), we remain uncertain as to the magnitude of its effectiveness and the mechanisms by which it may be effective. We employed a meta-analysis and critical narrative synthesis to examine the effectiveness of feedback for SBME procedural…

  10. Measurements and simulations for peak electrical load reduction in cooling dominated climate

    International Nuclear Information System (INIS)

    Sadineni, Suresh B.; Boehm, Robert F.

    2012-01-01

    Peak electric demand due to cooling load in the Desert Southwest region of the US has been an issue for the electrical energy suppliers. To address this issue, a consortium has been formed between the University of Nevada Las Vegas, Pulte Homes (home builder) and NV Energy (local utility) in order to reduce the peak load by more than 65%. The implemented strategies that were used to accomplish that goal consist of energy efficiency in homes, onsite electricity generation through roof integrated PV, direct load control, and battery storage at the substation level. The simulation models developed using building energy analysis software were validated against measured data. The electrical energy demand for the upgraded home during peak period (1:00–7:00 PM) decreased by approximately 37% and 9% compared to a code standard home of the same size, due to energy efficiency and PV generation, respectively. The total decrease in electrical demand due to energy efficiency and PV generation during the peak period is 46%. Additionally, a 2.2 °C increase in thermostat temperature from 23.9 °C to 26.1 °C between 4:00 PM and 7:00 PM has further decreased the average demand during the peak period by 69% of demand from a standard home. -- Highlights: ► A study to demonstrate peak load reductions of 65% at the substation. ► A new residential energy efficient community named Villa Trieste is being developed. ► The peak demand from the homes has decreased by 37% through energy efficiency. ► A 1.8 kWp system along with energy efficiency measures decreased peak by 46%.

  11. Simulation of the transient processes of load rejection under different accident conditions in a hydroelectric generating set

    Science.gov (United States)

    Guo, W. C.; Yang, J. D.; Chen, J. P.; Peng, Z. Y.; Zhang, Y.; Chen, C. C.

    2016-11-01

    Load rejection test is one of the essential tests that carried out before the hydroelectric generating set is put into operation formally. The test aims at inspecting the rationality of the design of the water diversion and power generation system of hydropower station, reliability of the equipment of generating set and the dynamic characteristics of hydroturbine governing system. Proceeding from different accident conditions of hydroelectric generating set, this paper presents the transient processes of load rejection corresponding to different accident conditions, and elaborates the characteristics of different types of load rejection. Then the numerical simulation method of different types of load rejection is established. An engineering project is calculated to verify the validity of the method. Finally, based on the numerical simulation results, the relationship among the different types of load rejection and their functions on the design of hydropower station and the operation of load rejection test are pointed out. The results indicate that: The load rejection caused by the accident within the hydroelectric generating set is realized by emergency distributing valve, and it is the basis of the optimization for the closing law of guide vane and the calculation of regulation and guarantee. The load rejection caused by the accident outside the hydroelectric generating set is realized by the governor. It is the most efficient measure to inspect the dynamic characteristics of hydro-turbine governing system, and its closure rate of guide vane set in the governor depends on the optimization result in the former type load rejection.

  12. Methods for Detecting Early Warnings of Critical Transitions in Time Series Illustrated Using Simulated Ecological Data

    Science.gov (United States)

    Dakos, Vasilis; Carpenter, Stephen R.; Brock, William A.; Ellison, Aaron M.; Guttal, Vishwesha; Ives, Anthony R.; Kéfi, Sonia; Livina, Valerie; Seekell, David A.; van Nes, Egbert H.; Scheffer, Marten

    2012-01-01

    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. PMID:22815897

  13. A CRITICAL STUDY AND COMPARISON OF MANUFACTURING SIMULATION SOFTWARES USING ANALYTIC HIERARCHY PROCESS

    Directory of Open Access Journals (Sweden)

    ASHU GUPTA

    2010-03-01

    Full Text Available In a period of continuous change in global business environment, organizations, large and small, are finding it increasingly difficult to deal with, and adjust to the demands for such change. Simulation is a powerful tool for allowing designers imagines new systems and enabling them to both quantify and observe behavior. Currently the market offers a variety of simulation software packages. Some are less expensive than others. Some are generic and can be used in a wide variety of application areas while others are more specific. Some have powerful features for modeling while others provide only basic features. Modeling approaches and strategies are different for different packages. Companies are seeking advice about the desirable features of software for manufacturing simulation, depending on the purpose of its use. Because of this, the importance of an adequate approach to simulation software evaluation and comparison is apparent. This paper presents a critical evaluation of four widely used manufacturing simulators: NX-IDEAS, Star-CD, Micro Saint Sharp and ProModel. Following a review of research into simulation software evaluation, an evaluation and comparison of the above simulators is performed. This paper illustrates and assesses the role the Analytic Hierarchy Process (AHP played in simulation software evaluation and selection. The main purpose of this evaluation and comparison is to discover the suitability of certain types of simulators for particular purposes.

  14. Eight critical factors in creating and implementing a successful simulation program.

    Science.gov (United States)

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

    2014-01-01

    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.

  15. Subchannel analysis of a critical power test, using simulated BWR 8x8 fuel assembly

    International Nuclear Information System (INIS)

    Mitsutake, T.; Terasaka, H.; Yoshimura, K.; Oishi, M.; Inoue, A.; Akiyama, M.

    1990-01-01

    Critical power predictions have been compared with the critical power test data obtained in simulated BWR 8x8 fuel rod assemblies. Two analytical methods for the critical power prediction in rod assemblies are used in the prediction, which are the subchannel analysis using the COBRA/BWR subchannel computer code with empirical critical heat flux (CHF) correlations and the liquid film dryout estimation using the CRIPP-3F 'multi-fluid' computer code. Improvements in both the analytical methods were made for spacer effect modeling, though they were specific for application to the current BWR rod assembly type. In general a reasonable agreement was obtained, though comparisons, between the prediction and the obtained test data. (orig.)

  16. Colistin Population Pharmacokinetics after Application of a Loading Dose of 9 MU Colistin Methanesulfonate in Critically Ill Patients.

    Science.gov (United States)

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

    2015-12-01

    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, http://dx.doi.org/10.1128/AAC.01361-08; 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, http://dx.doi.org/10.1128/AAC.06426-11; 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, http://dx.doi.org/10.1128/AAC.01733-10). 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, while

  17. Scaling up watershed model parameters--Flow and load simulations of the Edisto River Basin

    Science.gov (United States)

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

    2014-01-01

    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

  18. Evaluation of a new methodology to simulate damage and wear of polyethylene hip replacements subjected to edge loading in hip simulator testing.

    Science.gov (United States)

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

    2018-05-01

    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, 106B: 1456-1462, 2018. © 2017 Wiley Periodicals, Inc.

  19. The effects of pressure dependent constitutive model to simulate concrete structures failure under impact loads

    Science.gov (United States)

    Mokhatar, S. N.; Sonoda, Y.; Kamarudin, A. F.; Noh, M. S. Md; Tokumaru, S.

    2018-04-01

    The main objective of this paper is to explore the effect of confining pressure in the compression and tension zone by simulating the behaviour of reinforced concrete/mortar structures subjected to the impact load. The analysis comprises the numerical simulation of the influences of high mass low speed impact weight dropping on concrete structures, where the analyses are incorporated with meshless method namely as Smoothed Particle Hydrodynamics (SPH) method. The derivation of the plastic stiffness matrix of Drucker-Prager (DP) that extended from Von-Mises (VM) yield criteria to simulate the concrete behaviour were presented in this paper. In which, the displacements for concrete/mortar structures are assumed to be infinitesimal. Furthermore, the influence of the different material model of DP and VM that used numerically for concrete and mortar structures are also discussed. Validation upon existing experimental test results is carried out to investigate the effect of confining pressure, it is found that VM criterion causes unreal impact failure (flexural cracking) of concrete structures.

  20. An Intensive, Simulation-Based Communication Course for Pediatric Critical Care Medicine Fellows.

    Science.gov (United States)

    Johnson, Erin M; Hamilton, Melinda F; Watson, R Scott; Claxton, Rene; Barnett, Michael; Thompson, Ann E; Arnold, Robert

    2017-08-01

    Effective communication among providers, families, and patients is essential in critical care but is often inadequate in the PICU. To address the lack of communication education pediatric critical care medicine fellows receive, the Children's Hospital of Pittsburgh PICU developed a simulation-based communication course, Pediatric Critical Care Communication course. Pediatric critical care medicine trainees have limited prior training in communication and will have increased confidence in their communication skills after participating in the Pediatric Critical Care Communication course. Pediatric Critical Care Communication is a 3-day course taken once during fellowship featuring simulation with actors portraying family members. Off-site conference space as part of a pediatric critical care medicine educational curriculum. Pediatric Critical Care Medicine Fellows. Didactic sessions and interactive simulation scenarios. Prior to and after the course, fellows complete an anonymous survey asking about 1) prior instruction in communication, 2) preparedness for difficult conversations, 3) attitudes about end-of-life care, and 4) course satisfaction. We compared pre- and postcourse surveys using paired Student t test. Most of the 38 fellows who participated over 4 years had no prior communication training in conducting a care conference (70%), providing bad news (57%), or discussing end-of-life options (75%). Across all four iterations of the course, fellows after the course reported increased confidence across many topics of communication, including giving bad news, conducting a family conference, eliciting both a family's emotional reaction to their child's illness and their concerns at the end of a child's life, discussing a child's code status, and discussing religious issues. Specifically, fellows in 2014 reported significant increases in self-perceived preparedness to provide empathic communication to families regarding many aspects of discussing critical care, end

  1. Design of a Mobile Agent-Based Adaptive Communication Middleware for Federations of Critical Infrastructure Simulations

    Science.gov (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.

  2. Effective teamwork and communication mitigate task saturation in simulated critical care air transport team missions.

    Science.gov (United States)

    Davis, Bradley; Welch, Katherine; Walsh-Hart, Sharon; Hanseman, Dennis; Petro, Michael; Gerlach, Travis; Dorlac, Warren; Collins, Jocelyn; Pritts, Timothy

    2014-08-01

    Critical Care Air Transport Teams (CCATTs) are a critical component of the United States Air Force evacuation paradigm. This study was conducted to assess the incidence of task saturation in simulated CCATT missions and to determine if there are predictable performance domains. Sixteen CCATTs were studied over a 6-month period. Performance was scored using a tool assessing eight domains of performance. Teams were also assessed during critical events to determine the presence or absence of task saturation and its impact on patient care. Sixteen simulated missions were reviewed and 45 crisis events identified. Task saturation was present in 22/45 (49%) of crisis events. Scoring demonstrated that task saturation was associated with poor performance in teamwork (odds ratio [OR] = 1.96), communication (OR = 2.08), and mutual performance monitoring (OR = 1.9), but not maintenance of guidelines, task management, procedural skill, and equipment management. We analyzed the effect of task saturation on adverse patient outcomes during crisis events. Adverse outcomes occurred more often when teams were task saturated as compared to non-task-saturated teams (91% vs. 23%; RR 4.1, p < 0.0001). Task saturation is observed in simulated CCATT missions. Nontechnical skills correlate with task saturation. Task saturation is associated with worsening physiologic derangements in simulated patients. Reprint & Copyright © 2014 Association of Military Surgeons of the U.S.

  3. Modification and application of the ATHLET-SC code to trans-critical simulations

    International Nuclear Information System (INIS)

    Fu, S.-W.; Zhou, C.; Xu, Z.-H.; Liu, X.-J.; Yang, Y.-H.; Cheng, H.

    2011-01-01

    In the simulation of trans-critical transients of Supercritical water cooled reactor (SCWR), calculation will terminate because of the sudden change in void fraction across the critical point. To solve this problem, a pseudo two-phase method is proposed with a virtual region of latent heat at pseudo-critical temperatures. A smooth variation of void fraction can be realized by using liquid-field conservation equations at temperatures lower than the pseudo-critical temperature, and vapor-field conservation equations at temperatures higher than the pseudo-critical temperature. Using this method, the system code ATHLET is modified to ATHLET-SC mod 2 on the basic of the previous modified version ATHLET-SC by Shanghai Jiao Tong University. The results of tests are verified that the calculation error with the pseudo two-phase method for supercritical fluid is acceptable, when the virtual region of latent heat is kept small. Moreover, the ATHLET-SC mod 2 code is used to simulate the pressurization and depressurization process of a single flow channel with the pressure transition as well as blowdown process. The results indicate a good applicability of the modified code. (author)

  4. Analysis of ex-core detector response measured during nuclear ship Mutsu land-loaded core critical experiment

    International Nuclear Information System (INIS)

    Itagaki, M.; Abe, J.I.; Kuribayashi, K.

    1987-01-01

    There are some cases where the ex-core neutron detector response is dependent not only on the fission source distribution in a core but also on neutron absorption in the borated water reflector. For example, an unexpectedly large response variation was measured during the nuclear ship Mutsu land-loaded core critical experiment. This large response variation is caused largely by the boron concentration change associated with the change in control rod positioning during the experiment. The conventional Crump-Lee response calculation method has been modified to take into account this boron effect. The correction factor in regard to this effect has been estimated using the one-dimensional transport code ANISN. The detector response variations obtained by means of this new calculation procedure agree well with the measured values recorded during the experiment

  5. How to Secure UPS Operation And Supply of Safety Critical Load During Abnormal Conditions in Upstream Supply

    International Nuclear Information System (INIS)

    Andersen, Gert; Kissling, Silvan; Laaser, Joerg

    2015-01-01

    UPS system design margins are usually given by manufacturer, but the events in Forsmark showed that these margins are not sufficient to protect UPS equipment and secure supply to critical loads. To withstand such events, it is not enough just to define margins for particular equipment. The overall plant design including environmental influences must be taken into consideration. For extreme environmental conditions, a UPS must include protection which design is matching to the upstream plant equipment. Immunity against abnormal conditions can not be finally guaranteed by higher margins. A limitation that excludes such influences must be implemented into the design. This presentation discusses possibilities to specify design margins, for rectifiers and inverters based on GUTOR thyristor and IGBT technology. It shows protection features to resist and solutions to limit overvoltages. (authors)

  6. 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.

    1998-06-01

    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.

  7. Experimental simulation and analysis of off-normal heat loads accompanying plasma disruptions

    International Nuclear Information System (INIS)

    Laan, J.G. van der; Bakker, J.; Stad, R.C.L. van der; Klippel, H.T.

    1990-12-01

    The plasma disruption heat load is simulated experimentally using a pulsed laser beam with high energy density and short pulse duration (0.2-20 mm) covering a certain range of ITER design values. The present status of the laser heat flux test facility and new experimental tools are described. Spatial and time resolved profiles of the laser beam are given. Experimental results are presented including the variation of angle of incidence of the laser beam relative to the material surface. The nature and effects of the induced vapour plume are discussed. Materials studied are relevant to the ITER design. Experimental results are compared with numerical calculations. Some implications for the design of First Wall and Divertor of ITER are addressed. (author). 13 refs.; 5 figs

  8. Energy consumption program: A computer model simulating energy loads in buildings

    Science.gov (United States)

    Stoller, F. W.; Lansing, F. L.; Chai, V. W.; Higgins, S.

    1978-01-01

    The JPL energy consumption computer program developed as a useful tool in the on-going building modification studies in the DSN energy conservation project is described. The program simulates building heating and cooling loads and computes thermal and electric energy consumption and cost. The accuracy of computations are not sacrificed, however, since the results lie within + or - 10 percent margin compared to those read from energy meters. The program is carefully structured to reduce both user's time and running cost by asking minimum information from the user and reducing many internal time-consuming computational loops. Many unique features were added to handle two-level electronics control rooms not found in any other program.

  9. Time domain simulation of the response of geometrically nonlinear panels subjected to random loading

    Science.gov (United States)

    Moyer, E. Thomas, Jr.

    1988-01-01

    The response of composite panels subjected to random pressure loads large enough to cause geometrically nonlinear responses is studied. A time domain simulation is employed to solve the equations of motion. An adaptive time stepping algorithm is employed to minimize intermittent transients. A modified algorithm for the prediction of response spectral density is presented which predicts smooth spectral peaks for discrete time histories. Results are presented for a number of input pressure levels and damping coefficients. Response distributions are calculated and compared with the analytical solution of the Fokker-Planck equations. RMS response is reported as a function of input pressure level and damping coefficient. Spectral densities are calculated for a number of examples.

  10. Comparative thermal cyclic test of different beryllium grades previously subjected to simulated disruption loads

    International Nuclear Information System (INIS)

    Gervash, A.; Giniyatulin, R.; Mazul, I.

    1999-01-01

    Considering beryllium as plasma facing armour this paper presents recent results obtained in Russia. A special process of joining beryllium to a Cu-alloy material structure is described and recent results of thermal cycling tests of such joints are presented. Summarizing the results, the authors show that a Cu-alloy heat sink structure armoured with beryllium can survive high heat fluxes (≥10 MW/m 2 ) during 1000 heating/cooling cycles without serious damage to the armour material and its joint. The principal feasibility of thermal cycling of beryllium grades and their joints directly in the core of a nuclear reactor is demonstrated and the main results of this test are presented. The paper also describes the thermal cycling of different beryllium grades having cracks initiated by previously applied high heat loads simulating plasma disruptions. (orig.)

  11. Molecular dynamics simulation of shock-wave loading of copper and titanium

    Science.gov (United States)

    Bolesta, A. V.; Fomin, V. M.

    2017-10-01

    At extreme pressures and temperatures common materials form new dense phases with compacted atomic arrangements. By classical molecular dynamics simulation we observe that FCC copper undergo phase transformation to BCC structure. The transition occurs under shock wave loading at the pressures above 80 GPa and corresponding temperatures above 2000 K. We calculate phase diagram, show that at these pressures and low temperature FCC phase of copper is still stable and discuss the thermodynamic reason for phase transformation at high temperature shock wave regime. Titanium forms new hexagonal phase at high pressure as well. We calculate the structure of shock wave in titanium and observe that shock front splits in three parts: elastic, plastic and phase transformation. The possibility of using a phase transition behind a shock wave with further unloading for designing nanocrystalline materials with a reduced grain size is also shown.

  12. Numerical Simulation of Shock Response and Dynamic Fracture of a Concrete Dam Subjected to Impact Load

    Directory of Open Access Journals (Sweden)

    Lu Lu

    2016-01-01

    Full Text Available The shock response and dynamic fracture of concrete gravity dams under impact load are the key problems to evaluate the antiknock safety of the dam. This study aims at understanding the effects of impact shock on the elastic response and dynamic fracture of concrete gravity dams. Firstly, this paper uses acceleration records of a concrete gravity dam under impact to establish the correct way to determine the concrete gravity dam of the fundamental frequency and present cut sheets multi-degree-of-freedom dynamic modeling. Under strong impact loading, the constitutive relation of concrete gravity dam and the highest frequency of the impact are uncertain. So, the main advantage of this method is avoiding the use of elastic modulus in the calculation. The result indicates that the calculation method is a reliable computational method for concrete gravity dams subjected to impact. Subsequently, the failure process of dam models was numerically simulated based on ABAQUS commercial codes. Finally, this paper puts forward suggestions for future research based on the results of the analysis.

  13. Investigation via numerical simulation of limiting currents in the presence of dielectric loads

    International Nuclear Information System (INIS)

    Baedke, W. C.

    2009-01-01

    An investigation of the space-charge-limited currents for unneutralized relativistic particle beams drifting through a dielectrically loaded cylindrical conductor is presented. The first limiting current expression investigated assumes a uniform axial velocity profile, is commonly found in the literature, and has been applied to solid and annular beams with and without a dielectric present. The second limiting current expression investigated is self-consistent and is developed for annular beams in the presence of a dielectric load provided that the beams' inner and outer radii are less than the dielectric inner radius. Comparing both of these expressions to particle-in-cell simulations shows that the first expression under predicts the limiting current by no more than 20% and no less than 10% for all geometries and relativistic mass factors considered. It is also shown that the second expression over predicts the limiting current for all scenarios investigated by as much as 20% and in certain cases only a few percent. In addition, estimates for the accumulated charge densities at the vacuum-dielectric interface are presented and the possibility of breakdown within the dielectric is addressed.

  14. A novel modeling to predict the critical current behavior of Nb$_{3}$Sn PIT strand under transverse load based on a scaling law and Finite Element Analysis

    CERN Document Server

    Wang, Tiening; Takayasu, Makoto; Bordini, Bernardo

    2014-01-01

    Superconducting Nb$_{3}$Sn 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 ...

  15. RELAP5 simulations of critical break experiments in the RD-14 test facility

    Energy Technology Data Exchange (ETDEWEB)

    Kim, I-G; Cho, Y-J; Lee, S [Korea Inst. of Nuclear Safety, Taejon (Korea, Republic of)

    1996-12-31

    RELAP5/MOD3 simulations of critical break tests in the RD-14 facility, modelling a loss of coolant in a CANDU reactor, were compared to the experimental results, and to CATHENA simulations of the early stage of the test. The RELAP5/MOD3 predicted thermal hydraulic behaviour reasonably well, but some discrepancies were observed after emergency cooling injection (ECI). Pressure differences between headers govern flow through the heated sections, particularly after ECI, and there is much uncertainty in the header pressures; further work is therefore recommended. 6 refs., 3 figs.

  16. 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

    2016-04-01

    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.

  17. Francis-99: Transient CFD simulation of load changes and turbine shutdown in a model sized high-head Francis turbine

    International Nuclear Information System (INIS)

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

    2017-01-01

    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. (paper)

  18. Francis-99: Transient CFD simulation of load changes and turbine shutdown in a model sized high-head Francis turbine

    Science.gov (United States)

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

    2017-01-01

    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.

  19. Computer Simulations to Support Science Instruction and Learning: A critical review of the literature

    Science.gov (United States)

    Smetana, Lara Kathleen; Bell, Randy L.

    2012-06-01

    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.

  20. Simulation of the d.c. critical current in superconducting sintered ceramics

    International Nuclear Information System (INIS)

    Riedinger, R.; Habig, P.; Hlil, E.K.; Arnaud, M.; Boulesteix, C.

    1990-01-01

    The new superconducting high-T c sintered ceramics can be described in some case as a lattice of interconnected rods, in other cases as a more or less random packing of parallelepiped crystallites; their size is about a few microns. The d.c. critical current at zero voltage of such a material is not related to the critical current of the bulk material, but to its granular structure. Indeed, the critical current between two adjacent cells is governed by the critical current of the weak link between them; this link behaves within some limits as a Josephson junction, the critical current of which is known. For our present problem, the system can be modeled as a lattice of Josephson junctions. We present here results for the d.c. critical current at zero voltage of lattices of identical Josephson junctions in two dimensions. The influence of the finiteness of size of the sample is examined. The relationship with normal conductivity simulations and percolation is discussed

  1. Critical heat flux detection in rods simulating fuel elements by using dilation method

    International Nuclear Information System (INIS)

    Mesquita, A.Z.

    1993-01-01

    In out-reactor heat transfer experiments, fuel elements are often simulated by electrically heated rods. In order to prevent the heating rod from being damaged by burnout, when the critical heat flux occurs a safety system is provided which checks the axial thermal expansion of the rod. In case of sudden temperature increase, the corresponding elongation causes a fast interruption of the electrical power supply. The experiments presented here show that this method is more effective than one that uses thermocouples. (author)

  2. 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)

    2017-05-15

    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.

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

    International Nuclear Information System (INIS)

    Kim, Seongil; Choi, Sangmin

    2017-01-01

    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.

  4. Skinfold creep under load of caliper. Linear visco- and poroelastic model simulations.

    Science.gov (United States)

    Nowak, Joanna; Nowak, Bartosz; Kaczmarek, Mariusz

    2015-01-01

    This paper addresses the diagnostic idea proposed in [11] to measure the parameter called rate of creep of axillary fold of tissue using modified Harpenden skinfold caliper in order to distinguish normal and edematous tissue. Our simulations are intended to help understanding the creep phenomenon and creep rate parameter as a sensitive indicator of edema existence. The parametric analysis shows the tissue behavior under the external load as well as its sensitivity to changes of crucial hydro-mechanical tissue parameters, e.g., permeability or stiffness. The linear viscoelastic and poroelastic models of normal (single phase) and oedematous tissue (twophase: swelled tissue with excess of interstitial fluid) implemented in COMSOL Multiphysics environment are used. Simulations are performed within the range of small strains for a simplified fold geometry, material characterization and boundary conditions. The predicted creep is the result of viscosity (viscoelastic model) or pore fluid displacement (poroelastic model) in tissue. The tissue deformations, interstitial fluid pressure as well as interstitial fluid velocity are discussed in parametric analysis with respect to elasticity modulus, relaxation time or permeability of tissue. The creep rate determined within the models of tissue is compared and referred to the diagnostic idea in [11]. The results obtained from the two linear models of subcutaneous tissue indicate that the form of creep curve and the creep rate are sensitive to material parameters which characterize the tissue. However, the adopted modelling assumptions point to a limited applicability of the creep rate as the discriminant of oedema.

  5. A Multiinstitutional Simulation Boot Camp for Pediatric Cardiac Critical Care Nurse Practitioners.

    Science.gov (United States)

    Brown, Kristen M; Mudd, Shawna S; Hunt, Elizabeth A; Perretta, Julianne S; Shilkofski, Nicole A; Diddle, J Wesley; Yurasek, Gregory; Bembea, Melania; Duval-Arnould, Jordan; Nelson McMillan, Kristen

    2018-03-10

    Assess the effect of a simulation "boot camp" on the ability of pediatric nurse practitioners to identify and treat a low cardiac output state in postoperative patients with congenital heart disease. Additionally, assess the pediatric nurse practitioners' confidence and satisfaction with simulation training. Prospective pre/post interventional pilot study. University simulation center. Thirty acute care pediatric nurse practitioners from 13 academic medical centers in North America. We conducted an expert opinion survey to guide curriculum development. The curriculum included didactic sessions, case studies, and high-fidelity simulation-based on high-complexity cases, congenital heart disease benchmark procedures, and a mix of lesion-specific postoperative complications. To cover multiple, high-complexity cases, we implemented Rapid Cycle Deliberate Practice method of teaching for selected simulation scenarios using an expert driven checklist. Knowledge was assessed with a pre-/posttest format (maximum score, 100%). A paired-sample t test showed a statistically significant increase in the posttest scores (mean [SD], pre test, 36.8% [14.3%] vs post test, 56.0% [15.8%]; p simulation. Median time improved overall "time to task" across these scenarios. There was a significant increase in the proportion of clinically time-sensitive tasks completed within 5 minutes (pre, 60% [30/50] vs post, 86% [43/50]; p = 0.003] Confidence and satisfaction were evaluated with a validated tool ("Student Satisfaction and Self-Confidence in Learning"). Using a five-point Likert scale, the participants reported a high level of satisfaction (4.7 ± 0.30) and performance confidence (4.8 ± 0.31) with the simulation experience. Although simulation boot camps have been used effectively for training physicians and educating critical care providers, this was a novel approach to educating pediatric nurse practitioners from multiple academic centers. The course improved overall knowledge, and the

  6. A critical look at the kinetic parameter values used in simulating the thermoluminescence glow-curve

    Energy Technology Data Exchange (ETDEWEB)

    Sadek, A.M., E-mail: dr_amrsadek@hotmail.com [Ionizing Radiation Metrology Department, National Institute for Standards, El-Haram, Giza (Egypt); Kitis, G. [Nuclear Physics and Elementary Particles Physics Section, Physics Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Makedonia (Greece)

    2017-03-15

    Objections against utilizing the peak fitting method in computing the kinetics parameters of thermoluminescence (TL) glow-peaks were discussed previously in the literature. These objections came through testing the accuracy of the peak fitting by applying on simulated peaks. The results showed that in some cases the simulated peaks may have unusual geometrical properties and do not reflect the real properties of TL peaks. Thereby, estimating the accuracy of the peak fitting by applying on such peaks would be misleading. Two main reasons may lead to unrealistic simulated peaks; the improper selection of the simulation inputs, and performing the TL simulation process via the heating stage only. It has been proved that considering the irradiation and the relaxation stages in the simulation process is crucial. However, there are other cases in which the analytical methods were not able to reveal the real values of the simulated peaks. These cases were successfully resolved using analytical expressions derived from the one trap-one recombination (OTOR) level model and the non-interactive multiple trap system (NMTS) model. A general conclusion can be drawn that the accuracy of the peak fitting method is critically dependent on the TL analytical expressions utilized in this method. The failure of this method in estimating the TL kinetic parameters should be attributed to the TL model equation utilized in fitting process. - Highlights: • Objections against using the TL peak fitting method are discussed. • Improper selection of simulation inputs may lead to non realistic TL peaks. • Considering the irradiation and the relaxation stages in simulation is crucial. • TL expressions could not describe TL peaks with unrealistic geometrical properties. • The accuracy of the peak fitting method depends on the model used in the fitting.

  7. A critical review of simulation-based medical education research: 2003-2009.

    Science.gov (United States)

    McGaghie, William C; Issenberg, S Barry; Petrusa, Emil R; Scalese, Ross J

    2010-01-01

    This article reviews and critically evaluates historical and contemporary research on simulation-based medical education (SBME). It also presents and discusses 12 features and best practices of SBME that teachers should know in order to use medical simulation technology to maximum educational benefit. This qualitative synthesis of SBME research and scholarship was carried out in two stages. Firstly, we summarised the results of three SBME research reviews covering the years 1969-2003. Secondly, we performed a selective, critical review of SBME research and scholarship published during 2003-2009. The historical and contemporary research synthesis is reported to inform the medical education community about 12 features and best practices of SBME: (i) feedback; (ii) deliberate practice; (iii) curriculum integration; (iv) outcome measurement; (v) simulation fidelity; (vi) skill acquisition and maintenance; (vii) mastery learning; (viii) transfer to practice; (ix) team training; (x) high-stakes testing; (xi) instructor training, and (xii) educational and professional context. Each of these is discussed in the light of available evidence. The scientific quality of contemporary SBME research is much improved compared with the historical record. Development of and research into SBME have grown and matured over the past 40 years on substantive and methodological grounds. We believe the impact and educational utility of SBME are likely to increase in the future. More thematic programmes of research are needed. Simulation-based medical education is a complex service intervention that needs to be planned and practised with attention to organisational contexts.

  8. Simulation-based crisis resource management training for pediatric critical care medicine: a review for instructors.

    Science.gov (United States)

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

    2012-03-01

    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.

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

    KAUST Repository

    Yucel, Abdulkadir C.

    2018-02-05

    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.

  10. Application of Galerkin meshfree methods to nonlinear thermo-mechanical simulation of solids under extremely high pulsed loading

    International Nuclear Information System (INIS)

    Ibáñez, Daniel Iglesias; García Orden, Juan C.; Brañas, B.; Carmona, J.M.; Molla, J.

    2013-01-01

    Highlights: • The paper presents a novel application of meshfree methods, valid for its implementation on a multibody framework. • Coupled nonlinear thermo-mechanical formulation is detailed and described in the reference configuration, as this allows to compute the shape functions only once. • We show the conditions in which future information induces inefficiency. • Beam parameters are the only information needed to apply the thermal load. • The solution procedure takes charge of updating the volumetric heat rate as the body moves and deforms. -- Abstract: Beam facing elements of the International Fusion Materials Irradiation Facility (IFMIF) Linear Particle Accelerator prototype (LIPAc) must stop 5–40 MeV D + ions with a peak current of 125 mA. The duty cycle of the beam loading varies from 0.1% to 100% (CW), depending on the device, with the ions being stopped in the first hundreds microns of the beam facing material. For intermediate duty cycles up to CW, the thermal load can be considered a heat flux load on the boundary, but this approximation gets too conservative as the duty cycle is reduced because the thermal diffusion becomes more important. Instant heat flux produced by the beam can reach up to 3 GW/m 2 in elements such as the beam dump and slits during short times of hundredths of microseconds. In these cases, the accuracy of the volumetric heat generation is critical for obtaining realistic results. Meshfree Galerkin methods discretize a continuum using scattered nodes. As opposed to FEM, no predefined connectivity is needed between the nodes, so C ∞ (infinitely differentiable) locally supported shape functions can be used to approximate both the trial and the test functions. This feature makes these type of methods well suited for those problems where the domain experiences very large deformations or has high gradients of the state variables. Radial basis (RBF) and moving least squares (MLS) functions have been applied to the

  11. Tank 241-AZ-101 criticality assessment resulting from pump jet mixing: Sludge mixing simulation

    Energy Technology Data Exchange (ETDEWEB)

    Onishi, Y.; Recknagle, K.

    1997-04-01

    Tank 241-AZ-101 (AZ-101) is one of 28 double-shell tanks located in the AZ farm in the Hanford Site`s 200 East Area. The tank contains a significant quantity of fissile materials, including an estimated 9.782 kg of plutonium. Before beginning jet pump mixing for mitigative purposes, the operations must be evaluated to demonstrate that they will be subcritical under both normal and credible abnormal conditions. The main objective of this study was to address a concern about whether two 300-hp pumps with four rotating 18.3-m/s (60-ft/s) jets can concentrate plutonium in their pump housings during mixer pump operation and cause a criticality. The three-dimensional simulation was performed with the time-varying TEMPEST code to determine how much the pump jet mixing of Tank AZ-101 will concentrate plutonium in the pump housing. The AZ-101 model predicted that the total amount of plutonium within the pump housing peaks at 75 g at 10 simulation seconds and decreases to less than 10 g at four minutes. The plutonium concentration in the entire pump housing peaks at 0.60 g/L at 10 simulation seconds and is reduced to below 0.1 g/L after four minutes. Since the minimum critical concentration of plutonium is 2.6 g/L, and the minimum critical plutonium mass under idealized plutonium-water conditions is 520 g, these predicted maximums in the pump housing are much lower than the minimum plutonium conditions needed to reach a criticality level. The initial plutonium maximum of 1.88 g/L still results in safety factor of 4.3 in the pump housing during the pump jet mixing operation.

  12. Tank 241-AZ-101 criticality assessment resulting from pump jet mixing: Sludge mixing simulation

    International Nuclear Information System (INIS)

    Onishi, Y.; Recknagle, K.

    1997-04-01

    Tank 241-AZ-101 (AZ-101) is one of 28 double-shell tanks located in the AZ farm in the Hanford Site's 200 East Area. The tank contains a significant quantity of fissile materials, including an estimated 9.782 kg of plutonium. Before beginning jet pump mixing for mitigative purposes, the operations must be evaluated to demonstrate that they will be subcritical under both normal and credible abnormal conditions. The main objective of this study was to address a concern about whether two 300-hp pumps with four rotating 18.3-m/s (60-ft/s) jets can concentrate plutonium in their pump housings during mixer pump operation and cause a criticality. The three-dimensional simulation was performed with the time-varying TEMPEST code to determine how much the pump jet mixing of Tank AZ-101 will concentrate plutonium in the pump housing. The AZ-101 model predicted that the total amount of plutonium within the pump housing peaks at 75 g at 10 simulation seconds and decreases to less than 10 g at four minutes. The plutonium concentration in the entire pump housing peaks at 0.60 g/L at 10 simulation seconds and is reduced to below 0.1 g/L after four minutes. Since the minimum critical concentration of plutonium is 2.6 g/L, and the minimum critical plutonium mass under idealized plutonium-water conditions is 520 g, these predicted maximums in the pump housing are much lower than the minimum plutonium conditions needed to reach a criticality level. The initial plutonium maximum of 1.88 g/L still results in safety factor of 4.3 in the pump housing during the pump jet mixing operation

  13. Critical levels and loads of atmospheric pollutants for terrestrial and aquatic ecosystems. The emergence of a scientific concept. Application potentials and their limits

    International Nuclear Information System (INIS)

    Landmann, G.

    1993-01-01

    The 'critical loads and levels' are defined as the highest atmospheric deposition rate or concentration of a gaseous pollutant, respectively, that will not cause harmful effects on sensitive elements of an ecosystem. The recent emergence of the concept of critical loads and levels is described, from the first explicit mention in 1986 to the production of the first European maps in 1991. The difficulties linked to the definition of the concept and to its english-derived terminology are discussed. The main approaches used for assessing critical loads and levels are briefly described. Important research is developed under the auspices of the Convention of Geneva (Long Range Transboundary Air Pollution Transport, UN-ECE), arising from intensive studies which have been carried out on the effects of air pollution on terrestrial and aquatic ecosystems for the past ten or fifteen years. Current knowledge is summarized, as well as the remaining gaps (and questions) which hinder the calculation of the critical thresholds. Finally, beyond the fundamental relevance of this scientifically sound and easily understood concept, its limits are pointed out. In brief, the 'critical loads and levels' concept is attractive and motivating to many scientists: it implies to apply an integrated and finalized approach, favors the prospecting of poorly known ecosystems and regions, and represents an interesting interface with decision makers

  14. A Monte Carlo simulation on critical current distribution of bent-damaged multifilamentary Bi2223 composite tape

    International Nuclear Information System (INIS)

    Ochiai, S.; Okuda, H.; Fujimoto, M.; Shin, J.K.; Oh, S.S.; Ha, D.W.

    2011-01-01

    We simulate critical current distribution of bent-damaged Bi2223 composite tape. We use a Monte Carlo method and a damage evolution model for simulation. With the present simulation approach, experimental results are described well. Critical current distribution stems mainly from difference in damage evolution. It was attempted to reproduce the measured critical current (I c ) distributions of the Bi2223 composite tape bent by 0-0.833% by simulation. Simulation was carried out with a Monte Carlo method in combination with a model that correlates the critical current to damage evolution. Two variables that differ from specimen to specimen were input in the simulation. One was the damage strain parameter, with which the difference in extent of damage among specimens was expressed. Another was the original critical current (I c0 ) values at zero bending strain. With the present simulation approach, the measured distributions of critical current at various bending strains, and the measured variations of average and coefficient of variation of critical current values with increasing bending strain were reproduced well.

  15. Simulation Study on the Deflection Response of the 921A Steel thin plate under Explosive Impact Load

    Science.gov (United States)

    Zhang, Yu-Xiang; Chen, Fang; Han, Yan

    2018-03-01

    The Ship cabin would be subject to high-intensity shock wave load when it is attacked by anti-ship weapons, causing its side board damaged. The time course of the deflection of the thin plate made of 921A steel in different initial conditions under the impact load is researched by theoretical analysis and numerical simulation. According to the theory of elastic-plastic deformation of the thin plate, the dynamic response equation of the thin plate under the explosion impact load is established with the method of energy, and the theoretical calculation value is compared with the result from the simulation method. It proved that the theoretical calculation method has better reliability and accuracy in different boundary size.

  16. Load theory behind the wheel: an experimental application of a cognitive model to simulated driving

    OpenAIRE

    Murphy, Gillian

    2017-01-01

    Load Theory is a prominent model of selective attention first proposed over twenty years ago. Load Theory is supported by a great many experimental and neuroimaging studies. There is however, little evidence that Load Theory can be applied to real world attention, though it has great practical potential. Driving, as an everyday task where failures of attention can have profound consequences, stands to benefit from the understanding of selective attention that Load Theory provides. The aim of ...

  17. Effect of linear and non-linear blade modelling techniques on simulated fatigue and extreme loads using Bladed

    Science.gov (United States)

    Beardsell, Alec; Collier, William; Han, Tao

    2016-09-01

    There is a trend in the wind industry towards ever larger and more flexible turbine blades. Blade tip deflections in modern blades now commonly exceed 10% of blade length. Historically, the dynamic response of wind turbine blades has been analysed using linear models of blade deflection which include the assumption of small deflections. For modern flexible blades, this assumption is becoming less valid. In order to continue to simulate dynamic turbine performance accurately, routine use of non-linear models of blade deflection may be required. This can be achieved by representing the blade as a connected series of individual flexible linear bodies - referred to in this paper as the multi-part approach. In this paper, Bladed is used to compare load predictions using single-part and multi-part blade models for several turbines. The study examines the impact on fatigue and extreme loads and blade deflection through reduced sets of load calculations based on IEC 61400-1 ed. 3. Damage equivalent load changes of up to 16% and extreme load changes of up to 29% are observed at some turbine load locations. It is found that there is no general pattern in the loading differences observed between single-part and multi-part blade models. Rather, changes in fatigue and extreme loads with a multi-part blade model depend on the characteristics of the individual turbine and blade. Key underlying causes of damage equivalent load change are identified as differences in edgewise- torsional coupling between the multi-part and single-part models, and increased edgewise rotor mode damping in the multi-part model. Similarly, a causal link is identified between torsional blade dynamics and changes in ultimate load results.

  18. Two-phase simulations of the full load surge in Francis turbines

    Science.gov (United States)

    Wack, J.; Riedelbauch, S.

    2016-11-01

    At off-design conditions, Francis turbines experience cavitation which may reduce the power output and can cause severe damage in the machine. Certain conditions can cause self-excited oscillations of the vortex rope in the draft tube at full load operating point. For the presented work, two-phase simulations are carried out at model scale on a domain ranging from the inlet of the spiral case to the outlet of the draft tube. At different locations, wall pressure measurements are available and compared to the simulation results. Furthermore, the dynamics of the cavity volume in the draft tube cone and at the trailing edge of the runner blades are investigated by comparing with high speed visualization. To account for the selfexcited behaviour, proper boundary conditions need to be set. In this work, the focus lies on the treatment of the boundary condition at the inlet. In the first step, the dynamic behaviour of the cavity regions is investigated using a constant mass flow. Thereafter, oscillations of the total pressure and mass flow rate are prescribed using various frequencies and amplitudes. This methodology enables to examine the response of the cavity dynamics due to different excitations. It can be observed that setting a constant mass flow boundary condition is not suitable to account for the self-excited behaviour. Prescribing the total pressure has the result that the frequency of the vapour volume oscillation is the same as the frequency of the excitation signal. Contrary to that, for an excitation with a mass flow boundary condition, the response of the system is not equal to the excitation.

  19. Greenhouse-gas-induced climatic change: A critical appraisal of simulations and observations

    International Nuclear Information System (INIS)

    Schlesinger, M.E.

    1990-01-01

    This book is the culmination of a Workshop on Greenhouse-Gas-Induced Climatic Change: A Critical Appraisal of Simulations and Observations which was held at the University of Massachusetts, Amherst, during 8--12 May 1989. The objectives of the Workshop were to: (1) present and evaluate the current status of climate model simulations of greenhouse-gas-induced changes of both the equilibrium and nonequilibrium (transient) climates; (2) present and assess the current status of the observations of global and regional climates from the beginning of the industrial revolution to the present, circa 1850 to 1989; (3) present reconstructions of climatic change during the last millennium to determine the ''natural variability'' of climate on the intra-century time scale; (4) critically evaluate whether or not the climate has changes from circa 1850 to 1989; and (5) compare the observations with the model simulations to ascertain whether a greenhouse-gas-induced climatic change has occurred and, if not, to estimate when in the future such a climatic change will likely become detectable against the background of the ''natural variability.''

  20. A numerical simulation of metallic cylindrical sandwich shells subjected to air blast loading

    Directory of Open Access Journals (Sweden)

    Lin Jing

    Full Text Available The dynamic response of cylindrical sandwich shells with aluminum foam cores subjected to air blast loading was investigated numerically in this paper. According to KNR theory, the nonlinear compressibility of the air and finite shock conditions were taken into account in the finite element model. Numerical simulation results show that the compression strain, which plays a key role on energy absorption, increases approximately linearly with normalized impulse, and reduces with increasing relative density or the ratio of face-sheet thickness and core thickness. An increase of the impulse will delay the equalization of top and bottom face-sheet velocities of sandwich shell, but there is a maximum value in the studied bound. A limited study of weight optimization was carried out for sandwich shells with respect to the respective geometric parameters, including face-sheet thickness, core thickness and core relative density. These numerical results are of worth to theoretical prediction and engineering application of cellular metal sandwich structures.

  1. High temperature testing - a contribution to alloy development, alloy qualification and simulation of component Loading

    International Nuclear Information System (INIS)

    Scholz, A.; Schwienheer, M.; Mueller, F.; Linn, S.; Schein, M.; Walther, C.; Berger, C.

    2007-01-01

    In parallel to continued developments of steam and gas turbines as well as traffic engineering machines on the one hand, and marginal conditions like low specific fuel consumption and sufficient environment-friendliness on the other hand, the aim of improving the degree of efficiency by augmenting process parameters such as temperature and pressure is being followed. These efforts impact especially components of thermic machines and facilities subject to high thermal and mechanic exposure. Still largely unexplored is the interaction between microstructure characteristics determined through chemical composition, production processes and heat treatment, changes in the microstructure due to multiaxial load and the time-dependent deformation and stability resulting hereof. With regard to this background, improved methods of material properties determination, their modelling and transfer on the component enable to optimize wall thicknesses and degrees of efficiency. In the course of evaluation of static and cyclic material properties carried out also on faulty specimens, uncertainties occur which can originate from the testing process and analysis, as well as being influenced by the material itself and its process of production. Altogether, the demand for reliable determination of material properties and methods of scatterband treatment and their mathematical-statistical evaluation is in business. For simulation, consistent material datasets that describe the complex interaction between temperature, period of exposure and type of exposure are needed. Summarizing, the tasks dealt with qualify the entire process from production to the operational behaviour of components. (Abstract Copyright [2007], Wiley Periodicals, Inc.) [de

  2. Transient Simulation of Speed-No Load Conditions With An Open-Source Based C++ Code

    Science.gov (United States)

    Casartelli, E.; Mangani, L.; Romanelli, G.; Staubli, T.

    2014-03-01

    Modern reversible pump-turbines can start in turbine operation very quickly, i.e. within few minutes. Unfortunately no clear design rules for runners with a stable start-up are available, so that certain machines can present unstable characteristics which lead to oscillations in the hydraulic system during synchronization. The so-called S-shape, i.e. the unstable characteristic in turbine brake operation, is defined by the change of sign of the slope of the head curve. In order to assess and understand this kind of instabilities with CFD, fast and reliable methods are needed. Using a 360 degrees model including the complete machine from spiral casing to draft tube the capabilities of a newly developed in-house tool are presented. An ad-hoc simulation is performed from no-load conditions into the S-shape in transient mode and using moving-mesh capabilities, thus being able to capture the opening process of the wicket gates, for example like during start-up. Beside the presentation of the computational methodology, various phenomena encounterd are analyzed and discussed, comparing them with measured and previously computed data, in order to show the capabilities of the developed procedure. Insight in detected phenomena is also given for global data like frequencies of vortical structures and local flow patterns.

  3. Transient Simulation of Speed-No Load Conditions With An Open-Source Based C++ Code

    International Nuclear Information System (INIS)

    Casartelli, E; Mangani, L; Romanelli, G; Staubli, T

    2014-01-01

    Modern reversible pump-turbines can start in turbine operation very quickly, i.e. within few minutes. Unfortunately no clear design rules for runners with a stable start-up are available, so that certain machines can present unstable characteristics which lead to oscillations in the hydraulic system during synchronization. The so-called S-shape, i.e. the unstable characteristic in turbine brake operation, is defined by the change of sign of the slope of the head curve. In order to assess and understand this kind of instabilities with CFD, fast and reliable methods are needed. Using a 360 degrees model including the complete machine from spiral casing to draft tube the capabilities of a newly developed in-house tool are presented. An ad-hoc simulation is performed from no-load conditions into the S-shape in transient mode and using moving-mesh capabilities, thus being able to capture the opening process of the wicket gates, for example like during start-up. Beside the presentation of the computational methodology, various phenomena encounterd are analyzed and discussed, comparing them with measured and previously computed data, in order to show the capabilities of the developed procedure. Insight in detected phenomena is also given for global data like frequencies of vortical structures and local flow patterns

  4. Tests of an alternating current propulsion subsystem for electric vehicles on a road load simulator

    Science.gov (United States)

    Stenger, F. J.

    1982-12-01

    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.

  5. Calculations of critical micelle concentration by dissipative particle dynamics simulations: the role of chain rigidity.

    Science.gov (United States)

    Lee, Ming-Tsung; Vishnyakov, Aleksey; Neimark, Alexander V

    2013-09-05

    Micelle formation in surfactant solutions is a self-assembly process governed by complex interplay of solvent-mediated interactions between hydrophilic and hydrophobic groups, which are commonly called heads and tails. However, the head-tail repulsion is not the only factor affecting the micelle formation. For the first time, we present a systematic study of the effect of chain rigidity on critical micelle concentration and micelle size, which is performed with the dissipative particle dynamics simulation method. Rigidity of the coarse-grained surfactant molecule was controlled by the harmonic bonds set between the second-neighbor beads. Compared to flexible molecules with the nearest-neighbor bonds being the only type of bonded interactions, rigid molecules exhibited a lower critical micelle concentration and formed larger and better-defined micelles. By varying the strength of head-tail repulsion and the chain rigidity, we constructed two-dimensional diagrams presenting how the critical micelle concentration and aggregation number depend on these parameters. We found that the solutions of flexible and rigid molecules that exhibited approximately the same critical micelle concentration could differ substantially in the micelle size and shape depending on the chain rigidity. With the increase of surfactant concentration, primary micelles of more rigid molecules were found less keen to agglomeration and formation of nonspherical aggregates characteristic of flexible molecules.

  6. Simulation of transport critical current of Bi2223/Ag tape with ferromagnetic shielding

    Energy Technology Data Exchange (ETDEWEB)

    Gu, C. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Beijing 100084 (China)], E-mail: guchen@tsinghua.edu.cn; Alamgir, A.K.M. [Faculty of Engineering, Yokohama National University, 75-9 Tokiwadai, Hodogaya, ku, Yokohama (Japan); Qu, T.M. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Beijing 100084 (China); Key Laboratory for Advanced Materials Processing Technology, Ministry of Education (China); Han, Z. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Beijing 100084 (China)

    2008-09-15

    Ferromagnetic shielding (FS) was coated onto the surface of the Bi2223/Ag multi-filamentary tape. Transport critical current of the Bi2223/Ag multi-filamentary tape with a FS was systematically studied by numerical simulation. In the help of a finite element analysis (FEA) tool, we are able to understand how the FS alters the flux inside the superconductor region and thus increases and decreases the critical current density locally. The results show the open FS function both positively and negatively to the performance of the tape. An optimization process was proposed, aiming to reach a tradeoff between I{sub c} increasing and less usage of the ferromagnetic material. Three important shielding parameters, shielding width, shielding thickness, and shielding material were taken into account.

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

    CERN Document Server

    Rosato, Vittorio; Kyriakides, Elias; Rome, Erich

    2016-01-01

    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...

  8. Simulation of transport critical current of Bi2223/Ag tape with ferromagnetic shielding

    International Nuclear Information System (INIS)

    Gu, C.; Alamgir, A.K.M.; Qu, T.M.; Han, Z.

    2008-01-01

    Ferromagnetic shielding (FS) was coated onto the surface of the Bi2223/Ag multi-filamentary tape. Transport critical current of the Bi2223/Ag multi-filamentary tape with a FS was systematically studied by numerical simulation. In the help of a finite element analysis (FEA) tool, we are able to understand how the FS alters the flux inside the superconductor region and thus increases and decreases the critical current density locally. The results show the open FS function both positively and negatively to the performance of the tape. An optimization process was proposed, aiming to reach a tradeoff between I c increasing and less usage of the ferromagnetic material. Three important shielding parameters, shielding width, shielding thickness, and shielding material were taken into account

  9. Critical point of Nf=3 QCD from lattice simulations in the canonical ensemble

    International Nuclear Information System (INIS)

    Li Anyi; Alexandru, Andrei; Liu, Keh-Fei

    2011-01-01

    A canonical ensemble algorithm is employed to study the phase diagram of N f =3 QCD using lattice simulations. We lock in the desired quark number sector using an exact Fourier transform of the fermion determinant. We scan the phase space below T c and look for an S-shape structure in the chemical potential, which signals the coexistence phase of a first order phase transition in finite volume. Applying Maxwell construction, we determine the boundaries of the coexistence phase at three temperatures and extrapolate them to locate the critical point. Using an improved gauge action and improved Wilson fermions on lattices with a spatial extent of 1.8 fm and quark masses close to that of the strange, we find the critical point at T E =0.925(5)T c and baryon chemical potential μ B E =2.60(8)T c .

  10. FELIX - a computer code for simulation of criticality excursions in liquid fissile solutions

    International Nuclear Information System (INIS)

    Gmal, B.; Weber, J.

    1989-01-01

    Knowledge of characteristic parameters like evolved power fission yield during an accidental excursion is of essential importance to estimate possible radiological consequences and resulting safety hazards. The computer code 'FELIX' simulates excursion characteristics of aqueous critical assemblies: Starting out from given initial conditions the space-dependent neutron kinetic equations are solved in one-dimensional geometry. Power, fission yield, reactivity and temperature are calculated as a function of time. Reactivity-feedback includes density effects and radiolytic gas voids. Results from calculations are compared with CRAC-experiments. (orig.)

  11. Dynamical simulation of a linear sigma model near the critical point

    Energy Technology Data Exchange (ETDEWEB)

    Wesp, Christian; Meistrenko, Alex; Greiner, Carsten [Institut fuer Theoretische Physik, Goethe-Universitaet Frankfurt, Max-von-Laue-Strasse 1, D-60438 Frankfurt (Germany); Hees, Hendrik van [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Strasse 1, D-60438 Frankfurt (Germany)

    2014-07-01

    The intention of this study is the search for signatures of the chiral phase transition. To investigate the impact of fluctuations, e.g. of the baryon number, on the transition or a critical point, the linear sigma model is treated in a dynamical 3+1D numerical simulation. Chiral fields are approximated as classical fields, quarks are described by quasi particles in a Vlasov equation. Additional dynamic is implemented by quark-quark and quark-sigma-field interaction. For a consistent description of field-particle interactions, a new Monte-Carlo-Langevin-like formalism has been developed and is discussed.

  12. Manual for calculating critical loads of heavy metals for soils and surface waters; preliminary guidelines for environmental quality criteria, calculation methods and input data

    NARCIS (Netherlands)

    Vries, de W.; Bakker, D.J.

    1996-01-01

    Methodologies are described for calculating critical loads of lead, cadmium, copper, zinc, nickel, chromium and mercury for soils and surface waters. The aspects which are discussed are: selection of a computation model, determination of environmental-quality criteria for the metals, collection of

  13. Ecological ranges for the pH and NO3 of syntaxa: a new basis for the estimation of critical loads for acid and nitrogen deposition

    NARCIS (Netherlands)

    Wamelink, G.W.W.; Goedhart, P.W.; Malinowska, A.H.; Frissel, J.Y.; Wegman, R.M.A.; Slim, P.A.; Dobben, van H.F.

    2011-01-01

    Question: Can the abiotic ranges of syntaxonomic units (associations) in terms of pH and nitrate concentration be estimated and then in principle be used to estimate critical loads for acid and nitrogen deposition? Location: Europe. Methods: Using splines, abiotic ranges of syntaxonomic units were

  14. Critical Loads of Acid Deposition for Wilderness Lakes in the Sierra Nevada (California) Estimated by the Steady-State Water Chemistry Model

    Science.gov (United States)

    Glenn D. Shaw; Ricardo Cisneros; Donald Schweizer; James O. Sickman; Mark E. Fenn

    2014-01-01

    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 (...

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

    Directory of Open Access Journals (Sweden)

    Eric Dumonteil

    2017-09-01

    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.

  16. Simulation-based multidisciplinary team training decreases time to critical operations for trauma patients.

    Science.gov (United States)

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

    2018-05-01

    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.

  17. Subject-specific computer simulation model for determining elbow loading in one-handed tennis backhand groundstrokes.

    Science.gov (United States)

    King, Mark A; Glynn, Jonathan A; Mitchell, Sean R

    2011-11-01

    A subject-specific angle-driven computer model of a tennis player, combined with a forward dynamics, equipment-specific computer model of tennis ball-racket impacts, was developed to determine the effect of ball-racket impacts on loading at the elbow for one-handed backhand groundstrokes. Matching subject-specific computer simulations of a typical topspin/slice one-handed backhand groundstroke performed by an elite tennis player were done with root mean square differences between performance and matching simulations of elbow loading for a topspin and slice one-handed backhand groundstroke is relatively small. In this study, the relatively small differences in elbow loading may be due to comparable angle-time histories at the wrist and elbow joints with the major kinematic differences occurring at the shoulder. Using a subject-specific angle-driven computer model combined with a forward dynamics, equipment-specific computer model of tennis ball-racket impacts allows peak internal loading, net impulse, and shock due to ball-racket impact to be calculated which would not otherwise be possible without impractical invasive techniques. This study provides a basis for further investigation of the factors that may increase elbow loading during tennis strokes.

  18. Dynamic simulation of knee-joint loading during gait using force-feedback control and surrogate contact modelling.

    Science.gov (United States)

    Walter, Jonathan P; Pandy, Marcus G

    2017-10-01

    The aim of this study was to perform multi-body, muscle-driven, forward-dynamics simulations of human gait using a 6-degree-of-freedom (6-DOF) model of the knee in tandem with a surrogate model of articular contact and force control. A forward-dynamics simulation incorporating position, velocity and contact force-feedback control (FFC) was used to track full-body motion capture data recorded for multiple trials of level walking and stair descent performed by two individuals with instrumented knee implants. Tibiofemoral contact force errors for FFC were compared against those obtained from a standard computed muscle control algorithm (CMC) with a 6-DOF knee contact model (CMC6); CMC with a 1-DOF translating hinge-knee model (CMC1); and static optimization with a 1-DOF translating hinge-knee model (SO). Tibiofemoral joint loads predicted by FFC and CMC6 were comparable for level walking, however FFC produced more accurate results for stair descent. SO yielded reasonable predictions of joint contact loading for level walking but significant differences between model and experiment were observed for stair descent. CMC1 produced the least accurate predictions of tibiofemoral contact loads for both tasks. Our findings suggest that reliable estimates of knee-joint loading may be obtained by incorporating position, velocity and force-feedback control with a multi-DOF model of joint contact in a forward-dynamics simulation of gait. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

  19. Application of SELECT and SWAT models to simulate source load, fate, and transport of fecal bacteria in watersheds.

    Science.gov (United States)

    Ranatunga, T.

    2017-12-01

    Modeling of fate and transport of fecal bacteria in a watershed is 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 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 from SELECT model were input to the SWAT model, and simulate the bacteria transport through the land and in-stream. The calibrated SWAT model was then used to estimate the indicator bacteria in-stream concentrations for future years based on regional land use, population and household forecast (up to 2040). Based on the reductions required to meet the water quality standards in-stream, the corresponding required source load reductions were estimated.

  20. Psychomotor skills and cognitive load training on a virtual reality laparoscopic simulator for tubal surgery is effective.

    Science.gov (United States)

    Bharathan, Rasiah; Vali, Saaliha; Setchell, Thomas; Miskry, Tariq; Darzi, Ara; Aggarwal, Rajesh

    2013-07-01

    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

  1. The Pneumatic Actuators As Vertical Dynamic Load Simulators On Medium Weighted Wheel Suspension Mechanism

    Science.gov (United States)

    Ka'ka, Simon; Himran, Syukri; Renreng, Ilyas; Sutresman, Onny

    2018-02-01

    Almost all of road damage can be caused by dynamic loads of vehicles that fluctuate according to the type of vehicle that passes through. This study aims to calculate the vertical dynamic load of the vehicle actually occurs on road construction by the mechanism of vehicle wheel suspension. Pneumatic cylinders driven by pressurized air directly load the spring and shock absorber installed on the wheels of the vehicle. The load fluctuations of the medium weight categorized vehicles are determined by the regulation of the amount of pressurized air that enters into the pneumatic cylinder chamber, pushing the piston and connecting rods. The displacement that occurs during compression on the spring and shock absorber, is substituted into the equation of vehicle dynamic load while taking into account the spring stiffness constant, and the fluid or damper gas coefficient. The results show that the magnitude of the displacement when the compression force works has significant influences to the amount of vertical dynamic load of the vehicle that overlies the road construction. The presence of dynamic load of vehicles that fluctuates and repeats, also affects on the reduction of road ability to receive the load. Experimental results using pneumatic actuators instead of real dynamic vehicle loads illustrate the characteristics of the relationship between work pressure and dynamic load. If the working pressure of P2 (bar) is greater, the vertical dynamic load Ft (N) that overloads the road structure is also greater. The associate graphs show that the shock absorber has a greater ability to reduce dynamic load vertically that burden the road structure when compared with the ability of screw spring.

  2. SGEM Hot Off the Press: ultrasound during critical care simulation: a randomized crossover study.

    Science.gov (United States)

    McKenna, Paul; Thoma, Brent; Milne, Ken; Bond, Chris

    2017-01-01

    As part of the Canadian Journal of Emergency Medicine's (CJEM) developing social media strategy, 1 we are collaborating with the Skeptics' Guide to Emergency Medicine (SGEM) to summarize and critically appraise the current emergency medicine (EM) literature using evidence-based medicine principles. In the "Hot Off the Press" series, we select original research manuscripts published in CJEM to be featured on the SGEM website/podcast 2 and discussed by the study authors and the online EM community. A similar collaboration is underway between the SGEM and Academic Emergency Medicine. What follows is a summary of the selected article the immediate post-publication synthesis from the SGEM podcast, commentary by the first author, and the subsequent discussion from the SGEM blog and other social media. Through this series, we hope to enhance the value, accessibility, and application of important, clinically relevant EM research. In this, the third SGEM HOP hosted collaboratively with CJEM, we discuss Olszynski et al.'s randomized crossover study evaluating the use of ultrasound simulator devices during critical care simulation. 3.

  3. A critical review of simulation-based mastery learning with translational outcomes.

    Science.gov (United States)

    McGaghie, William C; Issenberg, Saul B; Barsuk, Jeffrey H; Wayne, Diane B

    2014-04-01

    This article has two objectives. Firstly, we critically review simulation-based mastery learning (SBML) research in medical education, evaluate its implementation and immediate results, and document measured downstream translational outcomes in terms of improved patient care practices, better patient outcomes and collateral effects. Secondly, we briefly address implementation science and its importance in the dissemination of innovations in medical education and health care. This is a qualitative synthesis of SBML with translational (T) science research reports spanning a period of 7 years (2006-2013). We use the 'critical review' approach proposed by Norman and Eva to synthesise findings from 23 medical education studies that employ the mastery learning model and measure downstream translational outcomes. Research in SBML in medical education has addressed a range of interpersonal and technical skills. Measured outcomes have been achieved in educational laboratories (T1), and as improved patient care practices (T2), patient outcomes (T3) and collateral effects (T4). Simulation-based mastery learning in medical education can produce downstream results. Such results derive from integrated education and health services research programmes that are thematic, sustained and cumulative. The new discipline of implementation science holds promise to explain why medical education innovations are adopted slowly and how to accelerate innovation dissemination. © 2014 John Wiley & Sons Ltd.

  4. The use of simulated rainfall to study the discharge process and the influence factors of urban surface runoff pollution loads.

    Science.gov (United States)

    Qinqin, Li; Qiao, Chen; Jiancai, Deng; Weiping, Hu

    2015-01-01

    An understanding of the characteristics of pollutants on impervious surfaces is essential to estimate pollution loads and to design methods to minimize the impacts of pollutants on the environment. In this study, simulated rainfall equipment was constructed to investigate the pollutant discharge process and the influence factors of urban surface runoff (USR). The results indicated that concentrations of total suspended solids (TSS), total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (COD) appeared to be higher in the early period and then decreased gradually with rainfall duration until finally stabilized. The capacity and particle size of surface dust, rainfall intensity and urban surface slopes affected runoff pollution loads to a variable extent. The loads of TP, TN and COD showed a positive relationship with the surface dust capacity, whereas the maximum TSS load appeared when the surface dust was 0.0317 g·cm⁻². Smaller particle sizes (pollution carrying capacity of runoff, leading to higher pollution loads. Knowledge of the influence factors could assist in the management of USR pollution loads.

  5. Simulation of Irregular Waves and Wave Induced Loads on Wind Power Plants in Shallow Water

    Energy Technology Data Exchange (ETDEWEB)

    Trumars, Jenny [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Water Environment Transport

    2004-05-01

    The essay gives a short introduction to waves and discusses the problem with non-linear waves in shallow water and how they effect an offshore wind energy converter. The focus is on the realisation of non-linear waves in the time domain from short-term statistics in the form of a variance density spectrum of the wave elevation. For this purpose the wave transformation from deep water to the near to shore site of a wind energy farm at Bockstigen has been calculated with the use of SWAN (Simulating Waves Near Shore). The result is a wave spectrum, which can be used as input to the realisation. The realisation of waves is done by perturbation theory to the first and second-order. The properties calculated are the wave elevation, water particle velocity and acceleration. The wave heights from the second order perturbation equations are higher than those from the first order perturbation equations. This is also the case for the water particle kinematics. The increase of variance is significant between the first order and the second order realisation. The calculated wave elevation exhibits non-linear features as the peaks become sharper and the troughs flatter. The resulting forces are calculated using Morison's equation. For second order force and base moment there is an increase in the maximum values. The force and base moment are largest approximately at the zero up and down crossing of the wave elevation. This indicates an inertia dominated wave load. So far the flexibility and the response of the structure have not been taken into account. They are, however, of vital importance. For verification of the wave model the results will later on be compared with measurements at Bockstigen off the coast of Gotland in the Baltic Sea.

  6. Burst wait time simulation of CALIBAN reactor at delayed super-critical state

    International Nuclear Information System (INIS)

    Humbert, P.; Authier, N.; Richard, B.; Grivot, P.; Casoli, P.

    2012-01-01

    In the past, the super prompt critical wait time probability distribution was measured on CALIBAN fast burst reactor [4]. Afterwards, these experiments were simulated with a very good agreement by solving the non-extinction probability equation [5]. Recently, the burst wait time probability distribution has been measured at CEA-Valduc on CALIBAN at different delayed super-critical states [6]. However, in the delayed super-critical case the non-extinction probability does not give access to the wait time distribution. In this case it is necessary to compute the time dependent evolution of the full neutron count number probability distribution. In this paper we present the point model deterministic method used to calculate the probability distribution of the wait time before a prescribed count level taking into account prompt neutrons and delayed neutron precursors. This method is based on the solution of the time dependent adjoint Kolmogorov master equations for the number of detections using the generating function methodology [8,9,10] and inverse discrete Fourier transforms. The obtained results are then compared to the measurements and Monte-Carlo calculations based on the algorithm presented in [7]. (authors)

  7. Burst wait time simulation of CALIBAN reactor at delayed super-critical state

    Energy Technology Data Exchange (ETDEWEB)

    Humbert, P. [Commissariat a l' Energie Atomique CEA, Centre de Bruyeres-le-Chatel, 91297 Arpajon (France); Authier, N.; Richard, B.; Grivot, P.; Casoli, P. [Commissariat a l' Energie Atomique CEA, Centre de Valduc, 21120 Is-sur-Tille (France)

    2012-07-01

    In the past, the super prompt critical wait time probability distribution was measured on CALIBAN fast burst reactor [4]. Afterwards, these experiments were simulated with a very good agreement by solving the non-extinction probability equation [5]. Recently, the burst wait time probability distribution has been measured at CEA-Valduc on CALIBAN at different delayed super-critical states [6]. However, in the delayed super-critical case the non-extinction probability does not give access to the wait time distribution. In this case it is necessary to compute the time dependent evolution of the full neutron count number probability distribution. In this paper we present the point model deterministic method used to calculate the probability distribution of the wait time before a prescribed count level taking into account prompt neutrons and delayed neutron precursors. This method is based on the solution of the time dependent adjoint Kolmogorov master equations for the number of detections using the generating function methodology [8,9,10] and inverse discrete Fourier transforms. The obtained results are then compared to the measurements and Monte-Carlo calculations based on the algorithm presented in [7]. (authors)

  8. The effect of simulation courseware on critical thinking in undergraduate nursing students: multi-site pre-post study.

    Science.gov (United States)

    Shin, Hyunsook; Ma, Hyunhee; Park, Jiyoung; Ji, Eun Sun; Kim, Dong Hee

    2015-04-01

    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

  9. The Effects of Moderate- and High-Fidelity Patient Simulator Use on Critical Thinking in Associate Degree Nursing Students

    Science.gov (United States)

    Vieck, Jana

    2013-01-01

    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…

  10. 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

    2002-01-01

    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

  11. Finite element simulation of pressure-loaded phase-field fractures

    NARCIS (Netherlands)

    Singh, N.; Verhoosel, C.V.; van Brummelen, E.H.

    2018-01-01

    A non-standard aspect of phase-field fracture formulations for pressurized cracks is the application of the pressure loading, due to the fact that a direct notion of the fracture surfaces is absent. In this work we study the possibility to apply the pressure loading through a traction boundary

  12. Horizontal loading test by whole model specimen simulating inner concrete structure of PWR type nuclear power plant

    International Nuclear Information System (INIS)

    Furuya, Noriyuki; Sekine, Masataka; Kimura, Kozo; Yamaguchi, Yoshihiro; Yamaguchi, Tsuneo; Takeda, Toshikazu

    1985-01-01

    The Nuclear Power Engineering Test Center has performed a horizontal loading test by a whole model specimen simulating the inner concrete structure of a PWR type nuclear power plant in order to investigate restoring force characteristics of reactor buildings. This report describes the results of examination of applicability to the test results of analysis methods based on elastic theory. The analysis results of elastic stiffness, concrete cracking load, rebar yielding loads and ultimate strength were compared with the test results. According to this examination, it is recognized that even these analysis methods based on elastic theory are comparatively effective for analysis of an inner concrete structure of fairly complex configuration, although there are limits of the scope of applicability. (author)

  13. Enabling the Distributed Generation Market of High Temperature Fuel Cell and Absorption Chiller Systems to Support Critical and Commercial Loads

    Science.gov (United States)

    DiMola, Ashley M.

    Buildings account for over 18% of the world's anthropogenic Greenhouse Gas (GHG) emissions. As a result, a technology that can offset GHG emissions associated with buildings has the potential to save over 9 Giga-tons of GHG emissions per year. High temperature fuel cell and absorption chiller (HTFC/AC) technology offers a relatively low-carbon option for meeting cooling and electric loads for buildings while producing almost no criteria pollutants. GHG emissions in the state of California would decrease by 7.48 million metric tons per year if every commercial building in the State used HTFC/AC technology to meet its power and cooling requirements. In order to realize the benefits of HTFC/AC technology on a wide scale, the distributed generation market needs to be exposed to the technology and informed of its economic viability and real-world potential. This work characterizes the economics associated with HTFC/AC technology using select scenarios that are representative of realistic applications. The financial impacts of various input factors are evaluated and the HTFC/AC simulations are compared to the economics of traditional building utilities. It is shown that, in addition to the emissions reductions derived from the systems, HTFC/AC technology is financially preferable in all of the scenarios evaluated. This work also presents the design of a showcase environment, centered on a beta-test application, that presents (1) system operating data gathered using a custom data acquisition module, and (2) HTFC/AC technology in a clear and approachable manner in order to serve the target audience of market stakeholders.

  14. Simulation of a load change stress in a powertrain through practical examples; Simulation des Lastwechselschlags im Antriebsstrang anhand von Praxisbeispielen

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Jun; Vorwerk, Christoph [Ford-Werke GmbH, Koeln (Germany); Stoecker, Andreas; Laschet, Andreas [ARLA Maschinentechnik GmbH, Wipperfuerth (Germany); Gunning, Kieron; Bharj, Tej [Ford Motor Company Ltd., Dunton (United Kingdom)

    2011-07-01

    This article compares impacts during load changes with the actual vehicle and test rig measurements. By the means of variant studies, the acoustic optimisation potential of the single components relating to the holistic system is highlighted, especially the acoustic phenomenon of the load change impacts. For a better understanding of the system and the measured phenomena as well as a demonstration of the potential optimisation possibilities a complex torsional vibration model of the analysed drivetrain was created. With the use of modern CAE tools early in the development stage, the refinement possibilities in terms of the NVH sensitivity of the drivetrain can be predicted and the subsequent solutions determined. (orig.)

  15. Variability of electricity load patterns and its effect on demand response: A critical peak pricing experiment on Korean commercial and industrial customers

    International Nuclear Information System (INIS)

    Jang, Dongsik; Eom, Jiyong; Jae Park, Min; Jeung Rho, Jae

    2016-01-01

    To the extent that demand response represents an intentional electricity usage adjustment to price changes or incentive payments, consumers who exhibit more-variable load patterns on normal days may be capable of altering their loads more significantly in response to dynamic pricing plans. This study investigates the variation in the pre-enrollment load patterns of Korean commercial and industrial electricity customers and their impact on event-day loads during a critical peak pricing experiment in the winter of 2013. Contrary to conventional approaches to profiling electricity loads, this study proposes a new clustering technique based on variability indices that collectively represent the potential demand–response resource that these customers would supply. Our analysis reveals that variability in pre-enrollment load patterns does indeed have great predictive power for estimating their impact on demand–response loads. Customers in relatively low-variability clusters provided limited or no response, whereas customers in relatively high-variability clusters consistently presented large load impacts, accounting for most of the program-level peak reductions. This study suggests that dynamic pricing programs themselves may not offer adequate motivation for meaningful adjustments in load patterns, particularly for customers in low-variability clusters. - Highlights: • A method of clustering customers by variability indices is developed. • Customers in high-variability clusters provide substantial peak reductions. • Low-variability clusters exhibit limited reductions. • For low-variability customers, alternative policy instruments is well advised. • A model of discerning customer's demand response potential is suggested.

  16. Design and simulation of Macro-Fiber composite based serrated microflap for wind turbine blade fatigue load reduction

    Science.gov (United States)

    Sun, Xiao; Dai, Qingli; Bilgen, Onur

    2018-05-01

    A Macro-Fiber Composite (MFC) based active serrated microflap is designed in this research for wind turbine blades. Its fatigue load reduction potential is evaluated in normal operating conditions. The force and displacement output of the MFC-based actuator are simulated using a bimorph beam model. The work done by the aerodynamic, centripetal and gravitational forces acting on the microflap were calculated to determine the required capacity of the MFC-based actuator. MFC-based actuators with a lever mechanical linkage are designed to achieve the required force and displacement to activate the microflap. A feedback control scheme is designed to control the microflap during operation. Through an aerodynamic-aeroelastic time marching simulation with the designed control scheme, the time responses of the wind turbine blades are obtained. The fatigue analysis shows that the serrated microflap can reduce the standard deviation of the blade root flapwise bending moment and the fatigue damage equivalent loads.

  17. Simulation of Nitrogen and Phosphorus Load Runoff by a GIS-based Distributed Model for Chikugo River Watershed

    Science.gov (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.

  18. Comparison of simulated and measured response of load rejection on A hydro power plant model with mixed mode nonlinear controller

    Energy Technology Data Exchange (ETDEWEB)

    Babunski, Darko; Tuneski, Atanasko; Zaev, Emil [Faculty of Mechanical Engineering, ' Ss. Cyril and Methodius' University, Skopje (Macedonia, The Former Yugoslav Republic of)

    2014-07-01

    Revised Hydro Power Plant model of the IEEE working group recommended converted to state space model is used for simulation of transient response of hydro turbine, and verification was made using measurements of transients from real Hydro Power Plant (HPP). Nonlinear mixed model controller was designed and implemented into complete HPP simulation model and compared with PID with real parameters used in HPP, and with adjusted PID parameters with consideration of smallest frequency error. Verification of performance of the model was made comparing model response with measured load rejection, which is worst case of HPP operation. (Author)

  19. 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

    2016-10-01

    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.

  20. Discrete meso-element simulation of the failure behavior of short-fiber composites under dynamic loading

    International Nuclear Information System (INIS)

    Liu Wenyan; Tang, Z.P.; Liu Yunxin

    2000-01-01

    In recent years, more attention has been paid to a better understanding of the failure behavior and mechanism of heterogeneous materials at the meso-scale level. In this paper, the crack initiation and development in epoxy composites reinforced with short steel fibers under dynamic loading were simulated and analyzed with the 2D Discrete Meso-Element Dynamic Method. Results show that the damage process depends greatly on the binding property between matrix and fibers

  1. Numerical Simulation of the Ground Response to the Tire Load Using Finite Element Method

    Science.gov (United States)

    Valaskova, Veronika; Vlcek, Jozef

    2017-10-01

    Response of the pavement to the excitation caused by the moving vehicle is one of the actual problems of the civil engineering practice. The load from the vehicle is transferred to the pavement structure through contact area of the tires. Experimental studies show nonuniform distribution of the pressure in the area. This non-uniformity is caused by the flexible nature and the shape of the tire and is influenced by the tire inflation. Several tire load patterns, including uniform distribution and point load, were involved in the numerical modelling using finite element method. Applied tire loads were based on the tire contact forces of the lorry Tatra 815. There were selected two procedures for the calculations. The first one was based on the simplification of the vehicle to the half-part model. The characteristics of the vehicle model were verified by the experiment and by the numerical model in the software ADINA, when vehicle behaviour during the ride was investigated. Second step involved application of the calculated contact forces for the front axle as the load on the multi-layered half space representing the pavement structure. This procedure was realized in the software Plaxis and considered various stress patterns for the load. The response of the ground to the vehicle load was then analyzed. Axisymmetric model was established for this procedure. The paper presents the results of the investigation of the contact pressure distribution and corresponding reaction of the pavement to various load distribution patterns. The results show differences in some calculated quantities for different load patterns, which need to be verified by the experimental way when also ground response should be observed.

  2. Finite-time adaptive sliding mode force control for electro-hydraulic load simulator based on improved GMS friction model

    Science.gov (United States)

    Kang, Shuo; Yan, Hao; Dong, Lijing; Li, Changchun

    2018-03-01

    This paper addresses the force tracking problem of electro-hydraulic load simulator under the influence of nonlinear friction and uncertain disturbance. A nonlinear system model combined with the improved generalized Maxwell-slip (GMS) friction model is firstly derived to describe the characteristics of load simulator system more accurately. Then, by using particle swarm optimization (PSO) algorithm ​combined with the system hysteresis characteristic analysis, the GMS friction parameters are identified. To compensate for nonlinear friction and uncertain disturbance, a finite-time adaptive sliding mode control method is proposed based on the accurate system model. This controller has the ability to ensure that the system state moves along the nonlinear sliding surface to steady state in a short time as well as good dynamic properties under the influence of parametric uncertainties and disturbance, which further improves the force loading accuracy and rapidity. At the end of this work, simulation and experimental results are employed to demonstrate the effectiveness of the proposed sliding mode control strategy.

  3. 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

    2015-01-01

    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...... bending moment at the blade root of a large wind turbine as a function of wind speed, turbulence and shear exponent in the presence of model uncertainty and non-stationary noise in the output. The extreme responses are obtained by two widely accepted numerical aero-servo-elastic simulators, FAST...

  4. Exploring the use of a deterministic adjoint flux calculation in criticality Monte Carlo simulations

    International Nuclear Information System (INIS)

    Jinaphanh, A.; Miss, J.; Richet, Y.; Martin, N.; Hebert, A.

    2011-01-01

    The paper presents a preliminary study on the use of a deterministic adjoint flux calculation to improve source convergence issues by reducing the number of iterations needed to reach the converged distribution in criticality Monte Carlo calculations. Slow source convergence in Monte Carlo eigenvalue calculations may lead to underestimate the effective multiplication factor or reaction rates. The convergence speed depends on the initial distribution and the dominance ratio. We propose using an adjoint flux estimation to modify the transition kernel according to the Importance Sampling technique. This adjoint flux is also used as the initial guess of the first generation distribution for the Monte Carlo simulation. Calculated Variance of a local estimator of current is being checked. (author)

  5. First-Year Residents Outperform Third-Year Residents after Simulation-Based Education in Critical Care Medicine

    Science.gov (United States)

    Singer, Benjamin D.; Corbridge, Thomas C.; Schroedl, Clara J.; Wilcox, Jane E.; Cohen, Elaine R.; McGaghie, William C.; Wayne, Diane B.

    2012-01-01

    Introduction Prior research shows that gaps exist in internal medicine residents’ critical care knowledge and skills. The purpose of this study was to compare the bedside critical care competency of first-year residents who received a simulation-based educational intervention plus clinical training to third-year residents who received clinical training alone. Methods During their first three months of residency, a group of first-year residents completed a simulation-based educational intervention. A group of traditionally-trained third-year residents who did not receive simulation-based training served as a comparison group. Both groups were evaluated using a 20-item clinical skills assessment at the bedside of a patient receiving mechanical ventilation at the end of their medical intensive care unit rotation. Scores on the skills assessment were compared between groups. Results Simulator-trained first-year residents (n=40) scored significantly higher compared to traditionally-trained third-year residents (n=27) on the bedside assessment, 91.3% (95% CI 88.2% to 94.3%) vs. 80.9% (95% CI 76.8% to 85.0%), P = simulation-based educational intervention demonstrated higher clinical competency than third-year residents who did not undergo simulation training. Critical care competency cannot be assumed after clinical ICU rotations; simulation-based curricula can help ensure residents are proficient to care for critically ill patients. PMID:23222546

  6. The influences of load mass changing on inverted pendulum stability based on simulation study

    Science.gov (United States)

    Pangaribuan, Timbang; Nasruddin, M. N.; Marlianto, Eddy; Sigiro, Mula

    2017-09-01

    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.

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

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher

    2011-01-01

    In the analysis of structures subjected to stationary stochastic load processes the mean out-crossing rate plays an important role as it can be used to determine the extreme value distribution of any response, usually assuming that the sequence of mean out-crossings can be modelled as a Poisson...... be scaled down to its actual value. In the present paper the usefulness of this approach is investigated, considering problems related to wave loads on marine structures. Here the load scale parameter is conveniently taken as the square of the significant wave height....... 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...

  8. The influence of anaesthetists' experience on workload, performance and visual attention during simulated critical incidents.

    Science.gov (United States)

    Schulz, Christian M; Schneider, Erich; Kohlbecher, Stefan; Hapfelmeier, Alexander; Heuser, Fabian; Wagner, Klaus J; Kochs, Eberhard F; Schneider, Gerhard

    2014-10-01

    Development of accurate Situation Awareness (SA) depends on experience and may be impaired during excessive workload. In order to gain adequate SA for decision making and performance, anaesthetists need to distribute visual attention effectively. Therefore, we hypothesized that in more experienced anaesthetists performance is better and increase of physiological workload is less during critical incidents. Additionally, we investigated the relation between physiological workload indicators and distribution of visual attention. In fifteen anaesthetists, the increase of pupil size and heart rate was assessed in course of a simulated critical incident. Simulator log files were used for performance assessment. An eye-tracking device (EyeSeeCam) provided data about the anaesthetists' distribution of visual attention. Performance was assessed as time until definitive treatment. T tests and multivariate generalized linear models (MANOVA) were used for retrospective statistical analysis. Mean pupil diameter increase was 8.1% (SD ± 4.3) in the less experienced and 15.8% (±10.4) in the more experienced subjects (p = 0.191). Mean heart rate increase was 10.2% (±6.7) and 10.5% (±8.3, p = 0.956), respectively. Performance did not depend on experience. Pupil diameter and heart rate increases were associated with a shift of visual attention from monitoring towards manual tasks (not significant). For the first time, the following four variables were assessed simultaneously: physiological workload indicators, performance, experience, and distribution of visual attention between "monitoring" and "manual" tasks. However, we were unable to detect significant interactions between these variables. This experimental model could prove valuable in the investigation of gaining and maintaining SA in the operation theatre.

  9. STRESS LOADING SIMULATION OF HYDRO-MECHANICAL TRANSMISSION OF DUMP TRUCK

    OpenAIRE

    S. A. Sidorov

    2006-01-01

    The Transmission model and software package to investigate stress loading of a hydromechanical transmission of a dump truck have been developed. The given software package allows to model stress loading of transmission gears in taking-off and acceleration modes at various road resistance, positions of an engine control pedal and initial revolutions of an engine crankshaft, various laws of friction clutch switching and some other parameters that permit to reveal a rate of various operational m...

  10. 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

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

    CSIR Research Space (South Africa)

    Duvenhage, B

    2008-05-01

    Full Text Available Simulations with a large number of model instances make use of parallel architectures to improve performance. When using such a parallel architecture a challenge is to effectively distribute the simulation objects across the processing platforms...

  12. Investigation on the Performance of UPQC-Q for Voltage Sag Mitigation and PQ Improvement at a Critical Load Point

    OpenAIRE

    Basu, Malabika; Das, S. P.; Dubey, Gopal

    2008-01-01

    The unified power quality conditioner (UPQC) is one of the major custom power solutions, which is capable of mitigating the effect of supply voltage sag at the load end or at the point of common coupling (PCC) in a distributed network. It also prevents the propagation of the load current harmonics to the utility and improves the input power factor of the load. The control of series compensator (SERC) of the UPQC is such that it injects voltage in quadrature advance to the supply current. Thus...

  13. Simulation study of the ionizing front in the critical ionization velocity phenomenon

    International Nuclear Information System (INIS)

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

    1988-01-01

    Simulations of the Critical Ionization Velocity (CIV) for a neutral gas cloud moving across the static magnetic field are made. We treat a low-β plasma and use a 2-1/2 D electrostatic code linked with our Plasma and Neutral Interaction Code (PANIC). Our study is focused on the understanding of the interface between the neutral gas cloud and the surrounding plasma where the strong interaction takes place. We assume the existence of some hot electrons in the ambient plasma to provide a seed ionization for CIV. When the ionization starts a sheath-like structure is formed at the surface of the neutral gas (Ionizing Front). In that region the crossfield component of the electric field causes the electron to E x B drift with a velocity of the order of the neutral gas velocity times the square root of the ion to electron mass ratio. Thus the kinetic energy of the drifting electrons can be large enough for electron impact ionization. In addition a diamagnetic drift of the electron occurs due to the number density and temperature inhomogeneity in the ionization front. These drift currents excite the lower-hybrid waves with the wave k-vectors almost perpendicular to the neutral flow and magnetic field again resulting in electron heating and additional ionization. The overall structure is studied by developing a simple analytic model as well as making simulation runs. (author)

  14. 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

    2004-08-01

    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

  15. Modeling of phosphorus loads in sugarcane in a low-relief landscape using ontology-based simulation.

    Science.gov (United States)

    Kwon, Ho-Young; Grunwald, Sabine; Beck, Howard W; Jung, Yunchul; Daroub, Samira H; Lang, Timothy A; Morgan, Kelly T

    2010-01-01

    Water flow and P dynamics in a low-relief landscape manipulated by extensive canal and ditch drainage systems were modeled utilizing an ontology-based simulation model. In the model, soil water flux and processes between three soil inorganic P pools (labile, active, and stable) and organic P are represented as database objects. And user-defined relationships among objects are used to automatically generate computer code (Java) for running the simulation of discharge and P loads. Our objectives were to develop ontology-based descriptions of soil P dynamics within sugarcane- (Saccharum officinarum L.) grown farm basins of the Everglades Agricultural Area (EAA) and to calibrate and validate such processes with water quality monitoring data collected at one farm basin (1244 ha). In the calibration phase (water year [WY] 99-00), observed discharge totaled 11,114 m3 ha(-1) and dissolved P 0.23 kg P ha(-1); and in the validation phase (WY 02-03), discharge was 10,397 m3 ha(-1) and dissolved P 0.11 kg P ha(-). During WY 99-00 the root mean square error (RMSE) for monthly discharge was 188 m3 ha(-1) and for monthly dissolved P 0.0077 kg P ha(-1); whereas during WY 02-03 the RMSE for monthly discharge was 195 m3 ha(-1) and monthly dissolved P 0.0022 kg P ha(-1). These results were confirmed by Nash-Sutcliffe Coefficient of 0.69 (calibration) and 0.81 (validation) comparing measured and simulated P loads. The good model performance suggests that our model has promise to simulate P dynamics, which may be useful as a management tool to reduce P loads in other similar low-relief areas.

  16. MONOTONIC AND CYCLIC LOADING SIMULATION OF STRUCTURAL STEELWORK BEAM TO COLUMN BOLTED CONNECTIONS WITH CASTELLATED BEAM

    Directory of Open Access Journals (Sweden)

    SAEID ZAHEDI VAHID

    2013-08-01

    Full Text Available Recently steel extended end plate connections are commonly used in rigid steel frame due to its good ductility and ability for energy dissipation. This connection system is recommended to be widely used in special moment-resisting frame subjected to vertical monotonic and cyclic loads. However improper design of beam to column connection can leads to collapses and fatalities. Therefore extensive study of beam to column connection design must be carried out, particularly when the connection is exposed to cyclic loadings. This paper presents a Finite Element Analysis (FEA approach as an alternative method in studying the behavior of such connections. The performance of castellated beam-column end plate connections up to failure was investigated subjected to monotonic and cyclic loading in vertical and horizontal direction. The study was carried out through a finite element analysis using the multi-purpose software package LUSAS. The effect of arranging the geometry and location of openings were also been investigated.

  17. Experimental Simulation of Beryllium Armour Damage Under ITER-like Intense Transient Plasma Loads

    Energy Technology Data Exchange (ETDEWEB)

    Kupriyanov, I.; Basaleev, E.; Nikolaev, G.; Kurbatova, L., E-mail: igkupr@gmail.com [A.A. Bochvar High Technology Research Institute of Inorganic Material, Moscow (Russian Federation); Podkovyrov, V.; Zhitlukhin, A. [SRC RF TRINITI, Troitsk (Russian Federation); Khimchenko, L. L. [Project Centre of ITER, Moscow (Russian Federation)

    2012-09-15

    Full text: Beryllium will be used as a plasma facing material in the next generation of tokamaks such as ITER. During plasma operation in ITER, the plasma facing materials and components will be suffered by different kinds of loading which may affect their surface or their joint to the heat sink. In addition to quasi-stationary loadings which are caused by the normal cycling operation, the plasma facing components and materials may also be exposed to the intense short transient loads like disruptions, ELMs. All these events may lead to beryllium surface melting, cracking, evaporation and erosion. It is expected that the erosion of beryllium under transient plasma loads such as ELMs and disruptions will mainly determine a lifetime of ITER first wall. To obtain the experimental data for the evaluation of the beryllium armor lifetime and dust production under ITER-relevant transient loads, the advanced plasma gun QSPA-Be facility has been constructed in Bochvar Institute. This paper presents recent results of the experiments with Russian beryllium of TGP-56FW ITER grade. The mock-ups of a special design armored with two beryllium targets (80 x 80 x 10 mm{sup 3}) were tested by hydrogen plasma streams (5 cm in diameter) with pulse duration of 0.5 ms and heat load of 0.5 and 1.0 MJ/m{sup 2}. Experiments were performed at RT temperature. The evolution of surface microstructure and profile, cracks morphology and mass loss/gain under erosion process on the beryllium surface exposed to up to 250 shots will be presented and discussed. (author)

  18. 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)

    2007-05-15

    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.

  19. Simulation of reactor noise analysis measurement for light-water critical assembly TCA using MCNP-DSP

    International Nuclear Information System (INIS)

    Yamamoto, Toshihiro; Sakurai, Kiyoshi; Tonoike, Kotaro; Miyoshi, Yoshinori

    2001-01-01

    Reactor noise analysis methods using Monte Carlo technique have been proposed and developed in the field of nuclear criticality safety. The Monte Carlo simulation for noise analysis can be made by simulating physical phenomena in the course of neutron transport in a nuclear fuel as practically as possible. MCNP-DSP was developed by T. Valentine of ORNL for this purpose and it is a modified version of MCNP-4A. The authors applied this code to frequency analysis measurements performed in light-water critical assembly TCA. Prompt neutron generation times for critical and subcritical cores were measured by doing the frequency analysis of detector signals. The Monte Carlo simulations for these experiments were carried out using MCNP-DSP, and prompt neutron generation times were calculated. (author)

  20. A Load Balancing Scheme Using Federate Migration Based on Virtual Machines for Cloud Simulations

    Directory of Open Access Journals (Sweden)

    Xiao Song

    2015-01-01

    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.

  1. Treatment of compounds and alloys in radiation hydrodynamics simulations of ablative laser loading

    International Nuclear Information System (INIS)

    Swift, Damian C.; Gammel, J. Tinka; Clegg, Samuel M.

    2004-01-01

    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

  2. Sensitivity analysis of simulated SOA loadings using a variance-based statistical approach: SENSITIVITY ANALYSIS OF SOA

    Energy Technology Data Exchange (ETDEWEB)

    Shrivastava, Manish [Pacific Northwest National Laboratory, Richland Washington USA; Zhao, Chun [Pacific Northwest National Laboratory, Richland Washington USA; Easter, Richard C. [Pacific Northwest National Laboratory, Richland Washington USA; Qian, Yun [Pacific Northwest National Laboratory, Richland Washington USA; Zelenyuk, Alla [Pacific Northwest National Laboratory, Richland Washington USA; Fast, Jerome D. [Pacific Northwest National Laboratory, Richland Washington USA; Liu, Ying [Pacific Northwest National Laboratory, Richland Washington USA; Zhang, Qi [Department of Environmental Toxicology, University of California Davis, California USA; Guenther, Alex [Department of Earth System Science, University of California, Irvine California USA

    2016-04-08

    We investigate the sensitivity of secondary organic aerosol (SOA) loadings simulated by a regional chemical transport model to 7 selected tunable model parameters: 4 involving emissions of anthropogenic and biogenic volatile organic compounds, anthropogenic semi-volatile and intermediate volatility organics (SIVOCs), and NOx, 2 involving dry deposition of SOA precursor gases, and one involving particle-phase transformation of SOA to low volatility. We adopt a quasi-Monte Carlo sampling approach to effectively sample the high-dimensional parameter space, and perform a 250 member ensemble of simulations using a regional model, accounting for some of the latest advances in SOA treatments based on our recent work. We then conduct a variance-based sensitivity analysis using the generalized linear model method to study the responses of simulated SOA loadings to the tunable parameters. Analysis of SOA variance from all 250 simulations shows that the volatility transformation parameter, which controls whether particle-phase transformation of SOA from semi-volatile SOA to non-volatile is on or off, is the dominant contributor to variance of simulated surface-level daytime SOA (65% domain average contribution). We also split the simulations into 2 subsets of 125 each, depending on whether the volatility transformation is turned on/off. For each subset, the SOA variances are dominated by the parameters involving biogenic VOC and anthropogenic SIVOC emissions. Furthermore, biogenic VOC emissions have a larger contribution to SOA variance when the SOA transformation to non-volatile is on, while anthropogenic SIVOC emissions have a larger contribution when the transformation is off. NOx contributes less than 4.3% to SOA variance, and this low contribution is mainly attributed to dominance of intermediate to high NOx conditions throughout the simulated domain. The two parameters related to dry deposition of SOA precursor gases also have very low contributions to SOA variance

  3. Biotribological evaluation of artificial disc arthroplasty devices: influence of loading and kinematic patterns during in vitro wear simulation

    Science.gov (United States)

    Yue, James J.; Garcia, Rolando; Basson, Janet; Schwiesau, Jens; Fritz, Bernhard; Blömer, Wilhelm

    2008-01-01

    Wear simulation is an essential pre-clinical method to predict the mid- and long-term clinical wear behavior of newly introduced devices for total disc arthroplasty. The main requirement of a suitable method for spinal wear simulation has to be the ability to distinguish between design concepts and allow for a direct comparison of predicate devices. The objective of our study was to investigate the influence of loading and kinematic patterns based on two different protocols for spinal wear simulation (ISO/FDIS 18192-1 (2006) and ASTM F2423-05). In vitro wear simulation was performed with six activ® L lumbar artificial disc devices (Aesculap Tuttlingen, Germany). The applied kinematic pattern of movement was multidirectional for ISO (elliptic track) and unidirectional with a curvilinear shape for ASTM. Testing was done for 10 million cycles in the ISO loading mode and afterwards with the same specimens for 5 million cycles according to the ASTM protocol with a customized six-station servohydraulic spinal wear simulator (EndoLab Thansau, Germany). Gravimetrical and geometrical wear assessment, a slide track analysis correlated to an optical surface characterization, and an estimation of particle size and morphology were performed. The gravimetric wear rate for the first 10 million cycles was ISOinitial = 2.7 ± 0.3 mg/million cycles. During the ASTM test period (10–15 million cycles) a gravimetric wear rate of 0.14 ± 0.06 mg/million cycles was estimated. The wear rates between the ISO and ASTM driven simulations differ substantially (approximately 20-fold) and statistical analysis demonstrates a significant difference (p < 0.001) between the test groups. The main explanation of divergency between ISO and ASTM driven wear simulations is the multidirectional pattern of movement described in the ISO document resulting in a cross-shear stress on the polyethylene material. Due to previous retrieval observations, it seems to be very unlikely that a lumbar

  4. 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.

    1981-04-01

    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.

  5. 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

    2016-01-01

    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......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....... 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....

  6. 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

    2006-12-15

    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)

  7. 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

    1996-05-01

    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.

  8. Finite Element Simulation of Aluminium/GFRP Fibre Metal Laminate under Tensile Loading

    Science.gov (United States)

    Merzuki, M. N. M.; Rejab, M. R. M.; Romli, N. K.; Bachtiar, D.; Siregar, J.; Rani, M. F.; Salleh, Salwani Mohd

    2018-03-01

    The response of a fibre metal laminate (FML) model to the tensile loading is predicted through a computational approach. The FML consisted with layers of aluminum alloy and embedded with one layer of composite material, Glass fibre Reinforced Plastic (GFRP). The glass fibre and aluminium alloy 2024-0 was laminated by using thermoset epoxy. A compression moulding technique was used in the process of a FML fabrication. The aluminium has been roughen by a metal sanding method which to improve the bonding between the fibre and metal layer. The main objective of this paper is to determine the failure behaviour of the FML under the tensile loading. The responses on the FML under the tensile loading were numerically performed. The FML was modelled and analysed by using Abaqus/CAE 6.13 version. Based on the experimental and FE data of the tensile, the ultimate tensile stress is 120 MPa where delamination and fibre breakage happened. A numerical model was developed and agreed well with the experimental results. The laminate has an inelastic respond to increase the tensile loads which due to the plasticity of the aluminium layers.

  9. Road load simulation using the MF-Swift tire and OpenCRG road model

    NARCIS (Netherlands)

    Schmeitz, A.J.C.; Versteden, W.D.; Eguchi, T.

    2011-01-01

    On one hand automotive manufacturers are trying to reduce product development times, while on the other hand they are aiming to bring more products to the market. Since safely and reliability must always be guaranteed, they use CAE to achieve this. For calculating road loads accurately, the tire and

  10. Phosphorus and nitrogen loading depths in fluvial sediments following manure spill simulations

    Science.gov (United States)

    Manure spills that enter streams can devastate the aquatic ecosystem. The depth of nitrogen (N) and phosphorus (P) loading in fluvial sediments following a manure spill have not been documented. Thus, the objectives of this study were (i) to determine the depth of N and P contamination as a result o...

  11. Impact of Higher Fidelity Models on Simulation of Active Aerodynamic Load Control For Fatigue Damage Reduction

    NARCIS (Netherlands)

    Resor, B.; Wilson, D.; Berg, D.; Berg, J.; Barlas, T.; Van Wingerden, J.W.; Van Kuik, G.A.M.

    2010-01-01

    Active aerodynamic load control of wind turbine blades is being investigated by the wind energy research community and shows great promise, especially for reduction of turbine fatigue damage in blades and nearby components. For much of this work, full system aeroelastic codes have been used to

  12. 2D URANS simulation of aerodynamic loads on a pitching airfoil: Impact of computational parameters

    NARCIS (Netherlands)

    Geng, F.; Kalkman, I.M.; Suiker, A.S.J.; Blocken, B.J.E.

    2017-01-01

    A numerical study of aerodynamic loads on pitching airfoils using Computational Fluid Dynamics (CFD) is challenging due complicated airfoil-vortex interactions and the possible occurrence of dynamic stall. In the latter case the combination of boundary layer transitions and airfoil oscillations

  13. 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

    2012-01-01

    attenuates the reduction in regional blood volumes during a simulated hemorrhagic challenge imposed via lower-body negative pressure (LBNP). Seven subjects underwent 30 mmHg LBNP while normothermic, during passive heat stress (increased internal temperature ~1°C), and while continuing to be heated after...... 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...... to normothermic levels. While normothermic, LBNP reduced blood volume in all regions (torso: 22±8%; heart: 18±6%; spleen: 15±8%). During LBNP while heat stressed, the reductions in blood volume in each region were markedly greater when compared to LBNP while normothermic (torso: 73±2%; heart: 72±3%; spleen: 72...

  14. 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.

    2014-01-01

    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

  15. 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

    2016-01-01

    -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...

  16. IDENTIFICATION OF WIND LOAD APPLIED TO THREE-DIMENSIONAL STRUCTURES BY VIRTUE OF ITS SIMULATION IN THE WIND TUNNEL

    Directory of Open Access Journals (Sweden)

    Doroshenko Sergey Aleksandrovich

    2012-10-01

    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.

  17. Development of total maximum daily loads for bacteria impaired watershed using the comprehensive hydrology and water quality simulation model.

    Science.gov (United States)

    Kim, Sang M; Brannan, Kevin M; Zeckoski, Rebecca W; Benham, Brian L

    2014-01-01

    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.

  18. Cyclic fatigue resistance tests of Nickel-Titanium rotary files using simulated canal and weight loading conditions

    Directory of Open Access Journals (Sweden)

    Ok-In Cho

    2013-02-01

    Full Text Available Objectives This study compared the cyclic fatigue resistance of nickel-titanium (NiTi files obtained in a conventional test using a simulated canal with a newly developed method that allows the application of constant fatigue load conditions. Materials and Methods ProFile and K3 files of #25/.06, #30/.06, and #40/.04 were selected. Two types of testing devices were built to test their fatigue performance. The first (conventional device prescribed curvature inside a simulated canal (C-test, the second new device exerted a constant load (L-test whilst allowing any resulting curvature. Ten new instruments of each size and brand were tested with each device. The files were rotated until fracture and the number of cycles to failure (NCF was determined. The NCF were subjected to one-way ANOVA and Duncan's post-hoc test for each method. Spearman's rank correlation coefficient was computed to examine any association between methods. Results Spearman's rank correlation coefficient (ρ = -0.905 showed a significant negative correlation between methods. Groups with significant difference after the L-test divided into 4 clusters, whilst the C-test gave just 2 clusters. From the L-test, considering the negative correlation of NCF, K3 gave a significantly lower fatigue resistance than ProFile as in the C-test. K3 #30/.06 showed a lower fatigue resistance than K3 #25/.06, which was not found by the C-test. Variation in fatigue test methodology resulted in different cyclic fatigue resistance rankings for various NiTi files. Conclusions The new methodology standardized the load during fatigue testing, allowing determination fatigue behavior under constant load conditions.

  19. Effects of formulation variables on viability of L. casei loaded in whey protein-Ca alginate microparticles in simulated in vivo conditions

    OpenAIRE

    Smilkov, Katarina; Petrusevska Tozi, Lidija; Petreska Ivanovska, Tanja; Geskovski, Nikola; Petkovska, Rumenka; Glavas Dodov, Marija; Baceva, Katerina; Dimitrovski, Dejan; Mladenovska, Kristina

    2011-01-01

    The objective of this work was to assess the influence of formulation variables of L. casei loaded whey protein-Ca-alginate microparticles on probiotic survival under different conditions, representing simulated in vivo environment.

  20. 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

    2016-01-01

    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...

  1. Load sharing with a local thermal network fed by a microcogenerator: Thermo-economic optimization by means of dynamic simulations

    International Nuclear Information System (INIS)

    Angrisani, Giovanni; Canelli, Michele; Rosato, Antonio; Roselli, Carlo; Sasso, Maurizio; Sibilio, Sergio

    2014-01-01

    The cogeneration is the combined production of electric and/or mechanical and thermal energy starting by a single energy source; in particular in this paper the analysis will be focused on a cogeneration system with electric power lower than 15 kW (micro-cogeneration). The paper analyzes a system consisting of a natural gas-fired micro-cogeneration unit (MCHP), a heat storage and a peak boiler. The system provides thermal and electric energy to two end-users, the former is a tertiary building (office), where the generation system is located, and the latter is a residential building connected to the former through a district heating micro-grid. In order to analyze the influence of climatic conditions, two different geographical locations in Italy (Benevento and Milano) are considered, that are also characterized by different natural gas and electricity tariffs. Particular attention is paid to the choice of the users, in order to obtain more stable and continuous electric and thermal loads (load sharing approach) and to increase the operating hours per year of the MCHP unit. The operation of the MCHP is governed by a control system, aimed to optimize a thermo-economic objective function. The models representing the components, the thermo-economic objective function and the buildings have been implemented in a widely used commercial software for building simulations. The models are calibrated and validated through data obtained from experimental tests carried out in the laboratory of the University of Sannio (Benevento). The results of the simulations highlight the potential benefits of the thermal load sharing approach. In particular, this study shows that an MCHP unit connected by means of a thermal micro-grid to different users in “load sharing mode” can obtain a high number of operating hours as well as significant energy (Primary Energy Saving) and environmental (avoided CO 2 equivalent emissions) benefits with respect to an appropriate reference system

  2. ArcNLET: A GIS-based software to simulate groundwater nitrate load from septic systems to surface water bodies

    Science.gov (United States)

    Rios, J. Fernando; Ye, Ming; Wang, Liying; Lee, Paul Z.; Davis, Hal; Hicks, Rick

    2013-03-01

    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

  3. Modeling and simulation of stand-alone hybrid power system with fuzzy MPPT for remote load application

    Directory of Open Access Journals (Sweden)

    Bogaraj T.

    2015-09-01

    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.

  4. Notes From the Field: Secondary Task Precision for Cognitive Load Estimation During Virtual Reality Surgical Simulation Training.

    Science.gov (United States)

    Rasmussen, Sebastian R; Konge, Lars; Mikkelsen, Peter T; Sørensen, Mads S; Andersen, Steven A W

    2016-03-01

    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 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.

  5. Structural biomechanics of the craniomaxillofacial skeleton under maximal masticatory loading: Inferences and critical analysis based on a validated computational model.

    Science.gov (United States)

    Pakdel, Amir R; Whyne, Cari M; Fialkov, Jeffrey A

    2017-06-01

    The trend towards optimizing stabilization of the craniomaxillofacial skeleton (CMFS) with the minimum amount of fixation required to achieve union, and away from maximizing rigidity, requires a quantitative understanding of craniomaxillofacial biomechanics. This study uses computational modeling to quantify the structural biomechanics of the CMFS under maximal physiologic masticatory loading. Using an experimentally validated subject-specific finite element (FE) model of the CMFS, the patterns of stress and strain distribution as a result of physiological masticatory loading were calculated. The trajectories of the stresses were plotted to delineate compressive and tensile regimes over the entire CMFS volume. The lateral maxilla was found to be the primary vertical buttress under maximal bite force loading, with much smaller involvement of the naso-maxillary buttress. There was no evidence that the pterygo-maxillary region is a buttressing structure, counter to classical buttress theory. The stresses at the zygomatic sutures suggest that two-point fixation of zygomatic complex fractures may be sufficient for fixation under bite force loading. The current experimentally validated biomechanical FE model of the CMFS is a practical tool for in silico optimization of current practice techniques and may be used as a foundation for the development of design criteria for future technologies for the treatment of CMFS injury and disease. Copyright © 2017 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

  6. Efficient approach for simulating response of multi-body structure in reactor core subjected to seismic loading

    International Nuclear Information System (INIS)

    Zhang Hongkun; Cen Song; Wang Haitao; Cheng Huanyu

    2012-01-01

    An efficient 3D approach is proposed for simulating the complicated responses of the multi-body structure in reactor core under seismic loading. By utilizing the rigid-body and connector functions of the software Abaqus, the multi-body structure of the reactor core is simplified as a mass-point system interlinked by spring-dashpot connectors. And reasonable schemes are used for determining various connector coefficients. Furthermore, a scripting program is also complied for the 3D parametric modeling. Numerical examples show that, the proposed method can not only produce the results which satisfy the engineering requirements, but also improve the computational efficiency more than 100 times. (authors)

  7. Loading and fracture response of CFRP-to-steel adhesively bonded joints with thick adherents – Part II: Numerical simulation

    DEFF Research Database (Denmark)

    Anyfantis, Konstantinos; Tsouvalis, Nicholas G.

    2013-01-01

    This work is focused on the numerical simulation of experimentally tested single lap joints, based on cohesive zone modeling techniques. Seven cases have been considered for analysis. The models were built in a 3-dimensional finite element space. The adherents were modeled with continuum elements...... the developed peel, in-plane and out-of-plane shear stresses over the adhesive area. Thus, the global measured response of all cases was justified by examining the stress fields and their variation through the loading history. © 2012 Elsevier Ltd. All rights reserved....

  8. 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)

    2016-10-15

    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.

  9. Simulating the phosphorus fluid-liquid phase transition up to the critical point

    International Nuclear Information System (INIS)

    Ghiringhelli, Luca M; Meijer, Evert Jan

    2007-01-01

    We report a Car-Parrinello molecular dynamics study of the temperature dependence of the fluid-liquid phase transition in phosphorous, involving the transformation of a molecular fluid phase into a network-like phase. We employed density-functional theory (DFT) with a gradient-corrected functional (B-LYP) to describe the electronic structure and interatomic interactions and performed simulations in a constant pressure ensemble. We spanned a temperature interval ranging from 2500 to 3500 K. With increasing temperature, we found that the structural conversion from the molecular P 4 fluid into the network liquid occurs at decreasing pressures, consistent with experimental observations. At lower temperatures the transition is characterized by a sudden increase of density in the sample. The magnitude of the density change decreases with increasing temperature and vanishes at 3500 K. In the temperature range 3100-3500 K we found signals of near- and super-criticality. We identified local structural changes that serve as seeds triggering the overall structural transition

  10. The utility of bedside simulation for training in critical care obstetrics.

    Science.gov (United States)

    Sheen, Jean-Ju; Lee, Colleen; Goffman, Dena

    2018-02-01

    Over the last 2 decades, the maternal mortality ratio in the United States has doubled from 7.4/100,000 live births in 1986 to 14.5/100,000 today. Despite great advances in health care, increasing rates of maternal morbidity and mortality in the United States have prompted calls to action to reverse this disturbing trend. Assisted reproductive technology has allowed women to delay childbearing to more advanced ages, resulting in a greater number of pregnancies complicated by one or more of the diseases associated with aging, such as cardiovascular disease, cancer, type 2 diabetes, and hypertension. The obesity epidemic, increasing rates of chronic diseases affecting pregnancy, steadily rising cesarean delivery rate with resulting complications, and medical advances allowing women with rare, but serious diseases to conceive contribute to rising maternal morbidity and mortality rates. Obstetric critical care simulation training may result in improved multidisciplinary teamwork and patient outcomes; and fewer medical and communication errors. Copyright © 2018 Elsevier Inc. All rights reserved.

  11. Scaling up watershed model parameters: flow and load simulations of the Edisto River Basin, South Carolina, 2007-09

    Science.gov (United States)

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

    2014-01-01

    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.

  12. Numerical Simulation for the Soil-Pile-Structure Interaction under Seismic Loading

    Directory of Open Access Journals (Sweden)

    Lifeng Luan

    2015-01-01

    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.

  13. Constant load and constant displacement stress corrosion in simulated water reactor environments

    International Nuclear Information System (INIS)

    Lloyd, G.J.

    1987-02-01

    The stress corrosion behaviour of selected water reactor constructional materials, as determined by constant load or constant displacement test techniques, is reviewed. Experimental results obtained using a very wide range of conditions have been collected in a form for easy reference. A discussion is given of some apparent trends in these data. The possible reasons for these trends are considered together with a discussion of how the observed discrepancies may be resolved. (author)

  14. Simulation of Structures Exhibiting Instability Under Thermal-Mechanical Transient Loading

    Science.gov (United States)

    2015-08-25

    stiffness of the system becomes singular when the structure loses stability. The tangent stiffness matrix of the system can be obtained from Eqs. (7) and...L. Virgin , Vibration of axially loaded structures, Cambridge University Press, 2007. [4] A. Przekoo and S. A. Rizzi, Dynamic snap-through of thin...walled structures by a reduced-order model, AIAA Journal, 45 (10) (2007) 2510-2519. [5] Y. Chandra, I. Stanciulescu, L. N. Virgin , T. G. Eason, and S. M

  15. Sleep restriction and cognitive load affect performance on a simulated marksmanship task.

    Science.gov (United States)

    Smith, Carl D; Cooper, Adam D; Merullo, Donna J; Cohen, Bruce S; Heaton, Kristin J; Claro, Pedro J; Smith, Tracey

    2017-11-24

    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.

  16. Simulation of cyclic stress-strain relation under non proportional loading

    International Nuclear Information System (INIS)

    Chen, X.; Zhu, Q.X.; Abel, A.

    1995-01-01

    A series of cyclic constitutive experiments have been conducted on 42 Cr Mo steel on MTS809 machine under tension-torsional loading. Thin-walled tube specimen were used. Two kinds of cruciform strain path have been investigated. The paper suggests a simple method for the calculation of stable cyclic stress and strain values based on a modified endochronic constitutive theory by redefined intrinsic time scale. (author). 6 refs., 3 figs

  17. Thermal simulation of different construction types in six climatic regions on heating and cooling loads

    CSIR Research Space (South Africa)

    Kumirai, T

    2012-10-01

    Full Text Available reduces its heating and cooling loads the most. 3. Applying both roof and ceiling insulation should always be avoided. 4. Building insulation is an effective intervention in all climatic regions. 5. Slightly increasing the thermal mass of a wall... were designed to evaluate the following: ? Case A ? base case ? Case B ? insulated walls ? Case C ? insulated walls and insulated ceiling ? Case D ? insulated walls, insulated ceiling and roof ? Case E ? increased thermal mass wall and insulated...

  18. Molecular Dynamics Simulations for Loading-Dependent Diffusion of CO2, SO2, CH4, and Their Binary Mixtures in ZIF-10: The Role of Hydrogen Bond.

    Science.gov (United States)

    Li, Li; Yang, Deshuai; Fisher, Trevor R; Qiao, Qi; Yang, Zhen; Hu, Na; Chen, Xiangshu; Huang, Liangliang

    2017-10-24

    The loading-dependent diffusion behavior of CH 4 , CO 2 , SO 2 , and their binary mixtures in ZIF-10 has been investigated in detail by using classical molecular dynamics simulations. Our simulation results demonstrate that the self-diffusion coefficient D i of CH 4 molecules decreases sharply and monotonically with the loading while those of both CO 2 and SO 2 molecules initially display a slight increase at low uptakes and follow a slow decrease at high uptakes. Accordingly, the interaction energies between CH 4 molecules and ZIF-10 remain nearly constant regardless of the loading due to the absence of hydrogen bonds (HBs), while the interaction energies between CO 2 (or SO 2 ) and ZIF-10 decease rapidly with the loading, especially at small amounts of gas molecules. Such different loading-dependent diffusion and interaction mechanisms can be attributed to the relevant HB behavior between gas molecules and ZIF-10. At low loadings, both the number and strength of HBs between CO 2 (or SO 2 ) molecules and ZIF-10 decrease obviously as the loading increases, which is responsible for the slight increase of their diffusion coefficients. However, at high loadings, their HB strength increases with the loading. Similar loading-dependent phenomena of diffusion, interaction, and HB behavior can be observed for CH 4, CO 2 , and SO 2 binary mixtures in ZIF-10, only associated with some HB competition between CO 2 and SO 2 molecules in the case of the CO 2 /SO 2 mixture.

  19. Load bearing and stiffness tailored NiTi implants produced by additive manufacturing: a simulation study

    Science.gov (United States)

    Rahmanian, Rasool; Shayesteh Moghaddam, Narges; Haberland, Christoph; Dean, David; Miller, Michael; Elahinia, Mohammad

    2014-03-01

    Common metals for stable long-term implants (e.g. stainless steel, Titanium and Titanium alloys) are much stiffer than spongy cancellous and even stiffer than cortical bone. When bone and implant are loaded this stiffness mismatch results in stress shielding and as a consequence, degradation of surrounding bony structure can lead to disassociation of the implant. Due to its lower stiffness and high reversible deformability, which is associated with the superelastic behavior, NiTi is an attractive biomaterial for load bearing implants. However, the stiffness of austenitic Nitinol is closer to that of bone but still too high. Additive manufacturing provides, in addition to the fabrication of patient specific implants, the ability to solve the stiffness mismatch by adding engineered porosity to the implant. This in turn allows for the design of different stiffness profiles in one implant tailored to the physiological load conditions. This work covers a fundamental approach to bring this vision to reality. At first modeling of the mechanical behavior of different scaffold designs are presented as a proof of concept of stiffness tailoring. Based on these results different Nitinol scaffolds can be produced by additive manufacturing.

  20. Simulation of dynamic traffic loading based on accelerated pavement testing (APT)

    CSIR Research Space (South Africa)

    Steyn, WJvdM

    2004-03-01

    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....

  1. 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

    2016-04-01

    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.

  2. Assessment of long-term knowledge retention following single-day simulation training for uncommon but critical obstetrical events

    Science.gov (United States)

    Vadnais, Mary A.; Dodge, Laura E.; Awtrey, Christopher S.; Ricciotti, Hope A.; Golen, Toni H.; Hacker, Michele R.

    2013-01-01

    Objective 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. Methods 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. Results 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. Conclusion 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. PMID:22191668

  3. 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

    2016-11-01

    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 B.to 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

  4. Structure and short time degradation studies of sodium zirconium phosphate ceramics loaded with simulated fast breeder (FBR) waste

    Energy Technology Data Exchange (ETDEWEB)

    Ananthanarayanan, A., E-mail: arvinda@barc.gov.in [Process Development Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Ambashta, R.D., E-mail: aritu@barc.gov.in [Process Development Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Sudarsan, V. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Ajithkumar, T. [Applied Catalysis Unit, National Chemical Laboratory, Pune 411008 (India); Sen, D.; Mazumder, S. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Wattal, P.K. [Process Development Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2017-04-15

    Sodium zirconium phosphate (NZP) ceramics have been prepared using conventional sintering and hot isostatic pressing (HIP) routes. The structure of NZP ceramics, prepared using the HIP route, has been compared with conventionally sintered NZP using a combination of X-ray diffraction (XRD) and ({sup 31}P and {sup 23}Na) nuclear magnetic resonance (NMR) spectroscopy techniques. It is observed that NZP with no waste loading is aggressive toward the steel HIP-can during hot isostatic compaction and significant fraction of cations from the steel enter the ceramic material. Waste loaded NZP samples (10 wt% simulated FBR waste) show significantly low can-interaction and primary NZP phase is evident in this material. Upon exposure of can-interacted and waste loaded NZP to boiling water and steam, {sup 31}P NMR does not detect any major modifications in the network structure. However, the {sup 23}Na NMR spectra indicate migration of Na{sup +} ions from the surface and possible re-crystallization. This is corroborated by Small-Angle Neutron Scattering (SANS) data and Scanning Electron Microscopy (SEM) measurements carried out on these samples.

  5. Molecular dynamics simulations of diffusion and clustering along critical isotherms of medium-chain n-alkanes.

    Science.gov (United States)

    Mutoru, J W; Smith, W; O'Hern, C S; Firoozabadi, A

    2013-01-14

    Understanding the transport properties of molecular fluids in the critical region is important for a number of industrial and natural systems. In the literature, there are conflicting reports on the behavior of the self diffusion coefficient D(s) in the critical region of single-component molecular systems. For example, D(s) could decrease to zero, reach a maximum, or remain unchanged and finite at the critical point. Moreover, there is no molecular-scale understanding of the behavior of diffusion coefficients in molecular fluids in the critical regime. We perform extensive molecular dynamics simulations in the critical region of single-component fluids composed of medium-chain n-alkanes-n-pentane, n-decane, and n-dodecane-that interact via anisotropic united-atom potentials. For each system, we calculate D(s), and average molecular cluster sizes κ(cl) and numbers N(cl) at various cluster lifetimes τ, as a function of density ρ in the range 0.2ρ(c) ≤ ρ ≤ 2.0ρ(c) at the critical temperature T(c). We find that D(s) decreases with increasing ρ but remains finite at the critical point. Moreover, for any given τ critical point.

  6. Atmospheric dry and wet deposition of sulphur and nitrogen species and assessment of critical loads of acidic deposition exceedance in South Africa

    Directory of Open Access Journals (Sweden)

    Stuart J. Piketh

    2011-03-01

    Full Text Available We tested the hypothesis that acidic atmospheric pollution deposition, originating from the South African central industrial area, poses an environmental threat across a larger region within the dispersal footprint. A network of 37 passive monitoring sites to measure SO2 and NO2 was operated from August 2005 to September 2007. The area extended over the entire northern and eastern interior of South Africa. Monitoring locations were chosen to avoid direct impacts from local sources such as towns, mines and highways. Dry deposition rates of SO2 and NO2 were calculated from the measured concentrations. Concentrations of sulphur and nitrogen species in wet deposition from a previous study were used in conjunction with measured rainfall for the years 2006 and 2007 to estimate the wet deposition over the region. The calculated total (non-organic acidic deposition formed the basis for an assessment of exceedance of critical loads based on sensitivity of the regional soils. Regional soil sensitivity was determined by combining two major soil attributes available in the World Inventory of Soil Emission Potentials (International Soil Reference and Information Centre. Results indicate that certain parts of the central pollution source area on the South African Highveld have the potential for critical load exceedance, while limited areas downwind show lower levels of exceedance. Areas upwind and remote areas up and downwind, including forested areas of the Drakensberg escarpment, do not show any exceedance of the critical loads.

  7. 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.

    1998-10-01

    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

  8. A study on special test stand of automatic and manual descent control in presence of simulated g-load effect

    Science.gov (United States)

    Glazkov, Yury; Artjuchin, Yury; Astakhov, Alexander; Vas'kov, Alexander; Malyshev, Veniamin; Mitroshin, Edward; Glinsky, Valery; Moiseenko, Vasily; Makovlev, Vyacheslav

    The development of aircraft-type reusable space vehicles (RSV) involves the problem of complete compatibility of automatic, director and manual control. Task decision is complicated, in particular, due to considerable quantitative and qualitative changes of vehicle dynamic characteristics, little stability margins (and even of unstability) of the RSV, and stringent requirements to control accuracy at some flight phases. Besides, during control a pilot is affected by g-loads which hamper motor activity and deteriorate its accuracy, alter the functional status of the visual analyser, and influence higher nervous activity. A study of g-load effects on the control efficiency, especially in manual and director modes, is of primary importance. The main tools for study of a rational selection of manual and director vehicle control systems and as an aid in formulating recommendations for optimum crew-automatic control system interactions are special complex and functional flight simulator test stands. The proposed simulator stand includes a powerful digital computer complex combined with the control system of the centrifuge. The interior of a pilot's vehicle cabin is imitated. A situation image system, pyscho-physical monitoring system, physician, centrifuge operator, and instructor stations are linked with the test stand.

  9. Dendritic cells loaded with HeLa-derived exosomes simulate an antitumor immune response.

    Science.gov (United States)

    Ren, Guoping; Wang, Yanhong; Yuan, Shexia; Wang, Baolian

    2018-05-01

    The aim of the present study was to investigate the effect of loading dendritic cells (DCs) with HeLa-derived exosomes on cytotoxic T-lymphocyte (CTL) responses, and the cytotoxic effects of CTL responses on the HeLa cell line. Ultrafiltration centrifugation combined with sucrose density gradient ultracentrifugation was applied to isolate exosomes (HeLa-exo) from the supernatant of HeLa cells. Morphological features of HeLa-exo were identified by transmission electron microscopy (TEM), and the expression of cluster of differentiation (CD)63 was detected by western blotting. Next, monocytes were isolated from peripheral blood and cultured with the removal of adherent cells to induce DC proliferation. DCs were then phenotypically characterized by flow cytometry. Finally, MTT assays were performed to analyze the effects of DCs loaded with HeLa-exo on T cell proliferation and cytotoxicity assays to evaluate the effect of CTL responses on HeLa cells. TEM revealed that HeLa-exo exhibit typical cup-shaped morphology with a diameter range of 30-100 nm. It was also identified that the CD63 surface antigen is expressed on HeLa-exo. Furthermore, monocyte-derived DCs were able to express CD1a, suggesting that DC induction was a success. DCs exhibited hair-like protrusions and other typical dendritic cell morphology. Furthermore, DCs loaded with HeLa-exo could enhance CTL proliferation and the cytotoxic activity of CTLs compared with DCs without HeLa-exo (PHeLa-exo may promote T cell proliferation and induce CTL responses to inhibit the growth of cervical cancer cells in vitro .

  10. Simulation of peri-implant bone healing due to immediate loading in dental implant treatments.

    Science.gov (United States)

    Chou, Hsuan-Yu; Müftü, Sinan

    2013-03-15

    The goal of this work was to investigate the role of immediate loading on the peri-implant bone healing in dental implant treatments. A mechano-regulatory tissue differentiation model that takes into account the stimuli through the solid and the fluid components of the healing tissue, and the diffusion of pluripotent stem cells into the healing callus was used. A two-dimensional axisymmetric model consisting of a dental implant, the healing callus tissue and the host bone tissue was constructed for the finite element analysis. Poroelastic material properties were assigned to the healing callus and the bone tissue. The effects of micro-motion, healing callus size, and implant thread design on the length of the bone-to-implant contact (BIC) and the bone volume (BV) formed in the healing callus were investigated. In general, the analysis predicted formation of a continuous layer of soft tissue along the faces of the implant which are parallel to the loading direction. This was predicted to be correlated with the high levels of distortional strain transferred through the solid component of the stimulus. It was also predicted that the external threads on the implant, redistribute the interfacial load, thus help reduce the high distortional stimulus and also help the cells to differentiate to bone tissue. In addition, the region underneath the implant apex was predicted to experience high fluid stimulus that results in the development of soft tissue. The relationship between the variables considered in this study and the outcome measures, BV and BIC, was found to be highly nonlinear. A three-way analysis of variance (ANOVA) of the results was conducted and it showed that micro-motion presents the largest hindrance to bone formation during healing. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Recent research and applications of numerical simulation for dynamic response of long-span bridges subjected to multiple loads.

    Science.gov (United States)

    Chen, Zhiwei; Chen, Bo

    2014-01-01

    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.

  12. Computer simulation of Masurca critical and subcritical experiments. Muse-4 benchmark. Final report

    International Nuclear Information System (INIS)

    2006-01-01

    The efficient and safe management of spent fuel produced during the operation of commercial nuclear power plants is an important issue. In this context, partitioning and transmutation (P and T) of minor actinides and long-lived fission products can play an important role, significantly reducing the burden on geological repositories of nuclear waste and allowing their more effective use. Various systems, including existing reactors, fast reactors and advanced systems have been considered to optimise the transmutation scheme. Recently, many countries have shown interest in accelerator-driven systems (ADS) due to their potential for transmutation of minor actinides. Much R and D work is still required in order to demonstrate their desired capability as a whole system, and the current analysis methods and nuclear data for minor actinide burners are not as well established as those for conventionally-fuelled systems. Recognizing a need for code and data validation in this area, the Nuclear Science Committee of the OECD/NEA has organised various theoretical benchmarks on ADS burners. Many improvements and clarifications concerning nuclear data and calculation methods have been achieved. However, some significant discrepancies for important parameters are not fully understood and still require clarification. Therefore, this international benchmark based on MASURCA experiments, which were carried out under the auspices of the EC 5. Framework Programme, was launched in December 2001 in co-operation with the CEA (France) and CIEMAT (Spain). The benchmark model was oriented to compare simulation predictions based on available codes and nuclear data libraries with experimental data related to TRU transmutation, criticality constants and time evolution of the neutronic flux following source variation, within liquid metal fast subcritical systems. A total of 16 different institutions participated in this first experiment based benchmark, providing 34 solutions. The large number

  13. MCNP calculation of the critical H_3BO_3 concentrations for the first fuel loading into the reactor core of NPP MO-3-4 units

    International Nuclear Information System (INIS)

    Vrban, B.; Lueley, J.; Farkas, G.; Hascik, J.; Hinca, R.; Petriska, M.; Slugen, V.

    2012-01-01

    The purpose of the analysis was the determination of critical H_3BO_3 concentrations for the first fuel loading into the reactor core of MO34 units using 2"n"d generation fuel during the first start-up of new unit using calculation code MCNP 1.60. H_3BO_3 concentrations were computed for the given temperature of the primary circuit and position of the 6"t"h safety control rod group. Because of the very first start-up of these units, detailed analyses of active-core parameters are required by National Regulatory Authority and needed for safe operation of nuclear facility. (authors)

  14. 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

    2014-10-01

    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.

  15. Computer simulation of yielding supports under static and short-term dynamic load

    Directory of Open Access Journals (Sweden)

    Kumpyak Oleg

    2018-01-01

    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.

  16. Finite element simulation of low velocity impact loading on a sandwich composite

    Directory of Open Access Journals (Sweden)

    Vishwas M.

    2018-01-01

    Full Text Available 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, peak load developed, deformation and von Mises stress and strain, are analyzed using commercially available analysis software. The results confirm that sandwich composite with jute epoxy skin absorbs approximately 20% more energy than glass epoxy skin. The contact force developed in jute epoxy skin is approximately 2.3 times less when compared to glass epoxy skin. von Mises stress developed is less in case of jute epoxy. The sandwich with jute epoxy skin deforms approximately 1.6 times more than that of same geometry of sandwich with glass epoxy skin. Thus exhibiting its elastic nature and making it potential candidate for low velocity impact application.

  17. Numerical Simulation of the Layer-Bylayer Destruction of Cylindrical Shells Under Explosive Loading

    Science.gov (United States)

    Abrosimov, N. A.; Novoseltseva, N. A.

    2015-09-01

    A technique of numerical analysis of the influence of reinforcement structure on the nature of the dynamic response and the process of layer-by-layer destruction of layered fiberglass cylindrical shells under an axisymmetric internal explosive loading is elaborated. The kinematic model of deformation of the laminate package is based on a nonclassical theory of shells. The geometric dependences are based on simple quadratic relations of the nonlinear theory of elasticity. The relationship between the stress and strain tensors are established by using Hooke's law for orthotropic bodies with account of degradation of stiffness characteristics of the multilayer composite due to the local destruction of some its elementary layers. An energetically consistent system of dynamic equations for composite cylindrical shells is obtained by minimizing the functional of total energy of the shell as a three-dimensional body. The numerical method for solving the formulated initial boundary-value problem is based on an explicit variational-difference scheme. Results confirming the reliability of the method used to analyze the influence of reinforcement structure on the character of destruction and the bearing capacity of pulse-loaded cylindrical shells are presented.

  18. Posterior Tibial Slope Angle Correlates With Peak Sagittal and Frontal Plane Knee Joint Loading During Robotic Simulations of Athletic Tasks

    Science.gov (United States)

    Bates, Nathaniel A.; Nesbitt, Rebecca J.; Shearn, Jason T.; Myer, Gregory D.; Hewett, Timothy E.

    2017-01-01

    Background 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. Purpose 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. Study Design Descriptive laboratory study. Methods 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. Results The mean (6SD) 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), latera