Hypervelocity Impact Initiation of Explosive Transfer Lines

NASA Technical Reports Server (NTRS)

Bjorkman, Michael D.; Christiansen, Eric L.

2012-01-01

The Gemini, Apollo and Space Shuttle spacecraft utilized explosive transfer lines (ETL) in a number of applications. In each case the ETL was located behind substantial structure and the risk of impact initiation by micrometeoroids and orbital debris was negligible. A current NASA program is considering an ETL to synchronize the actuation of pyrobolts to release 12 capture latches in a contingency. The space constraints require placing the ETL 50 mm below the 1 mm thick 2024-T72 Whipple shield. The proximity of the ETL to the thin shield prompted analysts at NASA to perform a scoping analysis with a finite-difference hydrocode to calculate impact parameters that would initiate the ETL. The results suggest testing is required and a 12 shot test program with surplused Shuttle ETL is scheduled for February 2012 at the NASA White Sands Test Facility. Explosive initiation models are essential to the analysis and one exists in the CTH library for HNS I, but not the HNS II used in the Shuttle 2.5 gr/ft rigid shielded mild detonating cord (SMDC). HNS II is less sensitive than HNS I so it is anticipated that these results using the HNS I model are conservative. Until the hypervelocity impact test results are available, the only check on the analysis was comparison with the Shuttle qualification test result that a 22 long bullet would not initiate the SMDC. This result was reproduced by the hydrocode simulation. Simulations of the direct impact of a 7 km/s aluminum ball, impacting at 0 degree angle of incidence, onto the SMDC resulted in a 1.5 mm diameter ball initiating the SMDC and 1.0 mm ball failing to initiate it. Where one 1.0 mm ball could not initiate the SMDC, a cluster of six 1.0 mm diameter aluminum balls striking simultaneously could. Thus the impact parameters that will result in initiating SMDC located behind a Whipple shield will depend on how well the shield fragments the projectile and spreads the fragments. An end-to-end simulation of the impact of an aluminum ball onto a Whipple shield covering SMDC is problematic due to the hydrocode fracture models. Regardless, two simulations were performed resulting in a 5 mm ball initiating the SMDC and a 4 mm ball failing to initiate the SMDC.

Exploration of Digital Circuits and Transistor-Level Testing in the DARPA TRUST Program

DTIC Science & Technology

2015-03-01

Transmission lines will be simulated by placing long metal wiring between two inverters . The metal wiring will be changed with each simulation to detect (if...though this could potentially cause a fabricated device to fail. Transmission lines were simulated by creating metal wiring between two inverters ...34 4.1 Initial Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 4.1.1 Inverter

Interactive Graphics Simulator: Design, Development, and Effectiveness/Cost Evaluation. Final Report.

ERIC Educational Resources Information Center

Pieper, William J.; And Others

This study was initiated to design, develop, implement, and evaluate a videodisc-based simulator system, the Interactive Graphics Simulator (IGS) for 6883 Converter Flight Control Test Station training at Lowry Air Force Base, Colorado. The simulator provided a means for performing task analysis online, developing simulations from the task…

High Fidelity Thermal Simulators for Non-Nuclear Testing: Analysis and Initial Results

NASA Technical Reports Server (NTRS)

Bragg-Sitton, Shannon M.; Dickens, Ricky; Dixon, David

2007-01-01

Non-nuclear testing can be a valuable tool in the development of a space nuclear power system, providing system characterization data and allowing one to work through various fabrication, assembly and integration issues without the cost and time associated with a full ground nuclear test. In a non-nuclear test bed, electric heaters are used to simulate the heat from nuclear fuel. Testing with non-optimized heater elements allows one to assess thermal, heat transfer, and stress related attributes of a given system, but fails to demonstrate the dynamic response that would be present in an integrated, fueled reactor system. High fidelity thermal simulators that match both the static and the dynamic fuel pin performance that would be observed in an operating, fueled nuclear reactor can vastly increase the value of non-nuclear test results. With optimized simulators, the integration of thermal hydraulic hardware tests with simulated neutronie response provides a bridge between electrically heated testing and fueled nuclear testing, providing a better assessment of system integration issues, characterization of integrated system response times and response characteristics, and assessment of potential design improvements' at a relatively small fiscal investment. Initial conceptual thermal simulator designs are determined by simple one-dimensional analysis at a single axial location and at steady state conditions; feasible concepts are then input into a detailed three-dimensional model for comparison to expected fuel pin performance. Static and dynamic fuel pin performance for a proposed reactor design is determined using SINDA/FLUINT thermal analysis software, and comparison is made between the expected nuclear performance and the performance of conceptual thermal simulator designs. Through a series of iterative analyses, a conceptual high fidelity design can developed. Test results presented in this paper correspond to a "first cut" simulator design for a potential liquid metal (NaK) cooled reactor design that could be applied for Lunar surface power. Proposed refinements to this simulator design are also presented.

High Fidelity, Fuel-Like Thermal Simulators for Non-Nuclear Testing: Analysis and Initial Test Results

NASA Technical Reports Server (NTRS)

Bragg-Sitton, Shannon M.; Dickens, Ricky; Dixon, David; Kapernick, Richard

2007-01-01

Non-nuclear testing can be a valuable tool in the development of a space nuclear power system, providing system characterization data and allowing one to work through various fabrication, assembly and integration issues without the cost and time associated with a full ground nuclear test. In a non-nuclear test bed, electric heaters are used to simulate the heat from nuclear fuel. Testing with non-optimized heater elements allows one to assess thermal, heat transfer. and stress related attributes of a given system, but fails to demonstrate the dynamic response that would be present in an integrated, fueled reactor system. High fidelity thermal simulators that match both the static and the dynamic fuel pin performance that would be observed in an operating, fueled nuclear reactor can vastly increase the value of non-nuclear test results. With optimized simulators, the integration of thermal hydraulic hardware tests with simulated neutronic response provides a bridge between electrically heated testing and fueled nuclear testing. By implementing a neutronic response model to simulate the dynamic response that would be expected in a fueled reactor system, one can better understand system integration issues, characterize integrated system response times and response characteristics and assess potential design improvements at relatively small fiscal investment. Initial conceptual thermal simulator designs are determined by simple one-dimensional analysis at a single axial location and at steady state conditions; feasible concepts are then input into a detailed three-dimensional model for comparison to expected fuel pin performance. Static and dynamic fuel pin performance for a proposed reactor design is determined using SINDA/FLUINT thermal analysis software, and comparison is made between the expected nuclear performance and the performance of conceptual thermal simulator designs. Through a series of iterative analyses, a conceptual high fidelity design is developed: this is followed by engineering design, fabrication, and testing to validate the overall design process. Test results presented in this paper correspond to a "first cut" simulator design for a potential liquid metal (NaK) cooled reactor design that could be applied for Lunar surface power. Proposed refinements to this simulator design are also presented.

Advanced Initiatives in Medical Simulation, 3rd Annual Conference to Create Awareness of Medical Simulation

DTIC Science & Technology

2006-06-30

Mexico suggested bringing together government agencies, academics, and industry representatives with an interest in medical simulation to identify ways...test, take online continuing medical education (CME) courses on electronic fetal monitoring and shoulder dystocia , and complete a physician

The High Energy Lightning Simulator (HELS) Test Facility for Testing Explosive Items

DTIC Science & Technology

1996-08-01

Center, Redstone Arsenal, AL Thomas E. Roy and David W. Bagwell AMTEC Corporation, Huntsville, AL ABSTRACT Details of the High Energy Lightning...simulated lightning testing of inerted missiles and inerted explosive items containing electrically initiated explosive trains is to determine the...penetrate the safety cages, which are electrically conductive and grounded, without loss of current. This transmission system consists of six large

Qualification of CASMO5 / SIMULATE-3K against the SPERT-III E-core cold start-up experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grandi, G.; Moberg, L.

SIMULATE-3K is a three-dimensional kinetic code applicable to LWR Reactivity Initiated Accidents. S3K has been used to calculate several international recognized benchmarks. However, the feedback models in the benchmark exercises are different from the feedback models that SIMULATE-3K uses for LWR reactors. For this reason, it is worth comparing the SIMULATE-3K capabilities for Reactivity Initiated Accidents against kinetic experiments. The Special Power Excursion Reactor Test III was a pressurized-water, nuclear-research facility constructed to analyze the reactor kinetic behavior under initial conditions similar to those of commercial LWRs. The SPERT III E-core resembles a PWR in terms of fuel type, moderator,more » coolant flow rate, and system pressure. The initial test conditions (power, core flow, system pressure, core inlet temperature) are representative of cold start-up, hot start-up, hot standby, and hot full power. The qualification of S3K against the SPERT III E-core measurements is an ongoing work at Studsvik. In this paper, the results for the 30 cold start-up tests are presented. The results show good agreement with the experiments for the reactivity initiated accident main parameters: peak power, energy release and compensated reactivity. Predicted and measured peak powers differ at most by 13%. Measured and predicted reactivity compensations at the time of the peak power differ less than 0.01 $. Predicted and measured energy release differ at most by 13%. All differences are within the experimental uncertainty. (authors)« less

2010 Joint Chemical Biological Radiological Nuclear (CBRN) Conference and Exhibition (BRIEFING CHARTS)

DTIC Science & Technology

2010-06-24

control Defensive Test Chamber • Certified for Chem-Bio simulants • Man-in-simulant (MIST) testing Bang Box • Explosive material synthesis and testing...Explosive material synthesis and testing Bang Box –Peroxide Explosives Properties – HMTD, TATP, DADP –Peroxide Explosives as Initiators –TATP... Synthesis –HMTD Synthesis –RDX Synthesis –ANFO Mixture Mustang VILLAGE Approved for public release; distribution is unlimited. • Hotel, Post Office

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simonen, F.A.; Johnson, K.I.; Liebetrau, A.M.

The VISA-II (Vessel Integrity Simulation Analysis code was originally developed as part of the NRC staff evaluation of pressurized thermal shock. VISA-II uses Monte Carlo simulation to evaluate the failure probability of a pressurized water reactor (PWR) pressure vessel subjected to a pressure and thermal transient specified by the user. Linear elastic fracture mechanics methods are used to model crack initiation and propagation. Parameters for initial crack size and location, copper content, initial reference temperature of the nil-ductility transition, fluence, crack-initiation fracture toughness, and arrest fracture toughness are treated as random variables. This report documents an upgraded version of themore » original VISA code as described in NUREG/CR-3384. Improvements include a treatment of cladding effects, a more general simulation of flaw size, shape and location, a simulation of inservice inspection, an updated simulation of the reference temperature of the nil-ductility transition, and treatment of vessels with multiple welds and initial flaws. The code has been extensively tested and verified and is written in FORTRAN for ease of installation on different computers. 38 refs., 25 figs.« less

Twenty Years On!: Updating the IEA BESTEST Building Thermal Fabric Test Cases for ASHRAE Standard 140

DOE Office of Scientific and Technical Information (OSTI.GOV)

Judkoff, R.; Neymark, J.

2013-07-01

ANSI/ASHRAE Standard 140, Standard Method of Test for the Evaluation of Building Energy Analysis Computer Programs applies the IEA BESTEST building thermal fabric test cases and example simulation results originally published in 1995. These software accuracy test cases and their example simulation results, which comprise the first test suite adapted for the initial 2001 version of Standard 140, are approaching their 20th anniversary. In response to the evolution of the state of the art in building thermal fabric modeling since the test cases and example simulation results were developed, work is commencing to update the normative test specification and themore » informative example results.« less

Twenty Years On!: Updating the IEA BESTEST Building Thermal Fabric Test Cases for ASHRAE Standard 140: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Judkoff, R.; Neymark, J.

2013-07-01

ANSI/ASHRAE Standard 140, Standard Method of Test for the Evaluation of Building Energy Analysis Computer Programs applies the IEA BESTEST building thermal fabric test cases and example simulation results originally published in 1995. These software accuracy test cases and their example simulation results, which comprise the first test suite adapted for the initial 2001 version of Standard 140, are approaching their 20th anniversary. In response to the evolution of the state of the art in building thermal fabric modeling since the test cases and example simulation results were developed, work is commencing to update the normative test specification and themore » informative example results.« less

Simulation study of the carbon dioxide enhanced oil recovery pilot test in the Griffithsville Field, Lincoln County, West Virginia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brummert, A.C.

1990-09-01

A carbon dioxide pilot test was conducted in the Griffithsville Field, Lincoln County, West Virginia, on a 90-acre tract containing nine 10-acre, normal, five-spot patterns arranged in a 3 {times} 3 matrix. This post-flood simulation study evaluates the initial pressure buildup phase of water injection, the carbon dioxide injection phase, and the chase water injection phase. Core data, geophysical well logs, fluid property data, well test data, and injection/production histories were used in setting up the data input record for the reservoir simulator. The reservoir simulator was IMEX, a four-component, black-oil reservoir simulator. 23 refs., 15 figs., 3 tabs.

Development and Application of a Portable Health Algorithms Test System

NASA Technical Reports Server (NTRS)

Melcher, Kevin J.; Fulton, Christopher E.; Maul, William A.; Sowers, T. Shane

2007-01-01

This paper describes the development and initial demonstration of a Portable Health Algorithms Test (PHALT) System that is being developed by researchers at the NASA Glenn Research Center (GRC). The PHALT System was conceived as a means of evolving the maturity and credibility of algorithms developed to assess the health of aerospace systems. Comprising an integrated hardware-software environment, the PHALT System allows systems health management algorithms to be developed in a graphical programming environment; to be tested and refined using system simulation or test data playback; and finally, to be evaluated in a real-time hardware-in-the-loop mode with a live test article. In this paper, PHALT System development is described through the presentation of a functional architecture, followed by the selection and integration of hardware and software. Also described is an initial real-time hardware-in-the-loop demonstration that used sensor data qualification algorithms to diagnose and isolate simulated sensor failures in a prototype Power Distribution Unit test-bed. Success of the initial demonstration is highlighted by the correct detection of all sensor failures and the absence of any real-time constraint violations.

Simulation of Fatigue Crack Initiation at Corrosion Pits With EDM Notches

NASA Technical Reports Server (NTRS)

Smith, Stephen W.; Newman, John A.; Piascik, Robert S.

2003-01-01

Uniaxial fatigue tests were conducted to compare the fatigue life of laboratory produced corrosion pits, similar to those observed in the shuttle main landing gear wheel bolt-hole, and an electro-discharged-machined (EDM) flaw. EDM Jaws are used to simulate corrosion pits during shuttle wheel (dynamometer) testing. The aluminum alloy, (AA 7050) laboratory fatigue tests were conducted to simulate the local stress level contained in the wheel bolt-hole. Under this high local stress condition, the EDM notch produced a fatigue life similar to test specimens containing corrosion pits of similar size. Based on the laboratory fatigue test results, the EDM Jaw (semi-circular disc shaped) produces a local stress state similar to corrosion pits and can be used to simulate a corrosion pit during the shuttle wheel dynamometer tests.

Tests of Halon 1301 test gas simulants

NASA Astrophysics Data System (ADS)

Carhart, H. W.; Leonard, J. T.; Dinenno, P. J.; Starchville, M. D.; Forssell, E. W.; Wong, J. T.

1989-02-01

All new and retrofit installations of Halon 1301 (CBrF3) total flooding fire protection systems in shipboard machinery spaces require full acceptance discharge test. It is desirable to use a suitable simulant test gas in these tests in view of current and future regulation of Halon 1301. Sulfur hexafluoride, SF6, and chlorodifluromethane R-22, were identified as candidate simulants on the basis of their similarity in physical properties to Halon 1301. These two candidates were then evaluated on the basis of leakage from an enclosure. SF6 was determined to be an excellent simulant for Halon 1301 when considering leakage from an enclosure. Further testing of SF6 and R-22 is planned for other important aspects of Halon 1301 systems, i.e., flow hydraulics, initial mixing.

Small Wind Research Turbine: Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corbus, D.; Meadors, M.

2005-10-01

The Small Wind Research Turbine (SWRT) project was initiated to provide reliable test data for model validation of furling wind turbines and to help understand small wind turbine loads. This report will familiarize the user with the scope of the SWRT test and support the use of these data. In addition to describing all the testing details and results, the report presents an analysis of the test data and compares the SWRT test data to simulation results from the FAST aeroelastic simulation model.

Improved fourth-year medical student clinical decision-making performance as a resuscitation team leader after a simulation-based curriculum.

PubMed

Ten Eyck, Raymond P; Tews, Matthew; Ballester, John M; Hamilton, Glenn C

2010-06-01

To determine the impact of simulation-based instruction on student performance in the role of emergency department resuscitation team leader. A randomized, single-blinded, controlled study using an intention to treat analysis. Eighty-three fourth-year medical students enrolled in an emergency medicine clerkship were randomly allocated to two groups differing only by instructional format. Each student individually completed an initial simulation case, followed by a standardized curriculum of eight cases in either group simulation or case-based group discussion format before a second individual simulation case. A remote coinvestigator measured eight objective performance end points using digital recordings of all individual simulation cases. McNemar chi2, Pearson correlation, repeated measures multivariate analysis of variance, and follow-up analysis of variance were used for statistical evaluation. Sixty-eight students (82%) completed both initial and follow-up individual simulations. Eight students were lost from the simulation group and seven from the discussion group. The mean postintervention case performance was significantly better for the students allocated to simulation instruction compared with the group discussion students for four outcomes including a decrease in mean time to (1) order an intravenous line; (2) initiate cardiac monitoring; (3) order initial laboratory tests; and (4) initiate blood pressure monitoring. Paired comparisons of each student's initial and follow-up simulations demonstrated significant improvement in the same four areas, in mean time to order an abdominal radiograph and in obtaining an allergy history. A single simulation-based teaching session significantly improved student performance as a team leader. Additional simulation sessions provided further improvement compared with instruction provided in case-based group discussion format.

Simulation optimization of the cathode deposit growth in a coaxial electrolyzer-refiner

NASA Astrophysics Data System (ADS)

Smirnov, G. B.; Fokin, A. A.; Markina, S. E.; Vakhitov, A. I.

2015-08-01

The results of simulation of the cathode deposit growth in a coaxial electrolyzer-refiner are presented. The sizes of the initial cathode matrix are optimized. The data obtained by simulation and full-scale tests of the precipitation of platinum from a salt melt are compared.

Advanced Control Design for Wind Turbines; Part I: Control Design, Implementation, and Initial Tests

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wright, A. D.; Fingersh, L. J.

The purpose of this report is to give wind turbine engineers information and examples of the design, testing through simulation, field implementation, and field testing of advanced wind turbine controls.

Report on the First Jacksboro MMLS Tests

DOT National Transportation Integrated Search

1999-12-01

This report outlines the two accelerated pavement tests completed in Jacksboro, Texas, using the 1/3-scale Model Mobile Load Simulator (MMLS3).The MMLS3 tests were initially commissioned to investigate the stripping phenomenon evident under conventio...

A seat cushion to provide realistic acceleration cues for aircraft simulators

NASA Technical Reports Server (NTRS)

Ashworth, B. R.

1976-01-01

A seat cushion to provide acceleration cues for aircraft simulator pilots was built, performance tested, and evaluated. The four cell seat, using a thin air cushion with highly responsive pressure control, attempts to reproduce the same events which occur in an aircraft seat under acceleration loading. The pressure controller provides seat cushion responses which are considered adequate for current high performance aircraft simulations. The initial tests of the seat cushions have resulted in excellent pilot opinion of the cushion's ability to provide realistic and useful cues to the simulator pilot.

Space Communications and Navigation (SCaN) Network Simulation Tool Development and Its Use Cases

NASA Technical Reports Server (NTRS)

Jennings, Esther; Borgen, Richard; Nguyen, Sam; Segui, John; Stoenescu, Tudor; Wang, Shin-Ywan; Woo, Simon; Barritt, Brian; Chevalier, Christine; Eddy, Wesley

2009-01-01

In this work, we focus on the development of a simulation tool to assist in analysis of current and future (proposed) network architectures for NASA. Specifically, the Space Communications and Navigation (SCaN) Network is being architected as an integrated set of new assets and a federation of upgraded legacy systems. The SCaN architecture for the initial missions for returning humans to the moon and beyond will include the Space Network (SN) and the Near-Earth Network (NEN). In addition to SCaN, the initial mission scenario involves a Crew Exploration Vehicle (CEV), the International Space Station (ISS) and NASA Integrated Services Network (NISN). We call the tool being developed the SCaN Network Integration and Engineering (SCaN NI&E) Simulator. The intended uses of such a simulator are: (1) to characterize performance of particular protocols and configurations in mission planning phases; (2) to optimize system configurations by testing a larger parameter space than may be feasible in either production networks or an emulated environment; (3) to test solutions in order to find issues/risks before committing more significant resources needed to produce real hardware or flight software systems. We describe two use cases of the tool: (1) standalone simulation of CEV to ISS baseline scenario to determine network performance, (2) participation in Distributed Simulation Integration Laboratory (DSIL) tests to perform function testing and verify interface and interoperability of geographically dispersed simulations/emulations.

First Steps towards an Interactive Real-Time Hazard Management Simulation

ERIC Educational Resources Information Center

Gemmell, Alastair M. D.; Finlayson, Ian G.; Marston, Philip G.

2010-01-01

This paper reports on the construction and initial testing of a computer-based interactive flood hazard management simulation, designed for undergraduates taking an applied geomorphology course. Details of the authoring interface utilized to create the simulation are presented. Students act as the managers of civil defence utilities in a fictional…

Initial conditions for cosmological N-body simulations of the scalar sector of theories of Newtonian, Relativistic and Modified Gravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valkenburg, Wessel; Hu, Bin, E-mail: valkenburg@lorentz.leidenuniv.nl, E-mail: hu@lorentz.leidenuniv.nl

2015-09-01

We present a description for setting initial particle displacements and field values for simulations of arbitrary metric theories of gravity, for perfect and imperfect fluids with arbitrary characteristics. We extend the Zel'dovich Approximation to nontrivial theories of gravity, and show how scale dependence implies curved particle paths, even in the entirely linear regime of perturbations. For a viable choice of Effective Field Theory of Modified Gravity, initial conditions set at high redshifts are affected at the level of up to 5% at Mpc scales, which exemplifies the importance of going beyond Λ-Cold Dark Matter initial conditions for modifications of gravitymore » outside of the quasi-static approximation. In addition, we show initial conditions for a simulation where a scalar modification of gravity is modelled in a Lagrangian particle-like description. Our description paves the way for simulations and mock galaxy catalogs under theories of gravity beyond the standard model, crucial for progress towards precision tests of gravity and cosmology.« less

Simulations of Convection Zone Flows and Measurements from Multiple Viewing Angles

NASA Technical Reports Server (NTRS)

Duvall, Thomas L.; Hanasoge, Shravan

2011-01-01

A deep-focusing time-distance measurement technique has been applied to linear acoustic simulations of a solar interior perturbed by convective flows. The simulations are for the full sphere for r/R greater than 0.2. From these it is straightforward to simulate the observations from different viewing angles and to test how multiple viewing angles enhance detectibility. Some initial results will be presented.

Development of Ground Test System For RKX-200EB

NASA Astrophysics Data System (ADS)

Yudhi Irwanto, Herma

2018-04-01

After being postponed for seven years, the development of RKX-200EB now restarts by initiating a ground test, preceding the real flight test. The series of the development starts from simulation test using the real vehicle and its components, focusing on a flight sequence test using hardware in the loop simulation. The result of the simulation shows that the autonomous control system in development is able to control the X tail fin vehicle, since take off using booster, separating booster-sustainer, making flight maneuver using sustainer with average cruise speed of 1000 km/h, and doing bank to maneuver up to ±40 deg heading to the target. The simulation result also shows that the presence of sustainer in vehicle control can expand the distance range by 162% (12.6 km) from its ballistic range using only a booster.

Environmentally Benign Battlefield Effects Black Smoke Simulator

DTIC Science & Technology

2006-11-01

tested and results Fuel Oxidizer Color of Smoke Density of Smoke Sugar (Sucrose) KNO3 Grey Medium Dextrin KNO3 Grey Thin Microcrystalline...design. 3.5 Initial Prototype Scale Fiberboard Testing Several quality black smoke formulations were identified in the small pellet testing to

Initial Stage Reference Search : Driver Simulators to Test Shared Controls, Limited Autonomy Vehicle Systems

DOT National Transportation Integrated Search

2015-09-01

This literature review and reference scanning focuses on the use of driver simulators for semiautonomous (or shared control) vehicle systems (2012present), including related research from other modes of transportation (e.g., rail or aviation). Foc...

Tradeoffs in Acceleration and Initialization of Superparameterized Global Atmospheric Models for MJO and Climate Science

NASA Astrophysics Data System (ADS)

Pritchard, M. S.; Bretherton, C. S.; DeMott, C. A.

2014-12-01

New trade-offs are discussed in the cloud superparameterization approach to explicitly representing deep convection in global climate models. Intrinsic predictability tests show that the memory of cloud-resolving-scale organization is not critical for producing desired modes of organized convection such as the Madden-Julian Oscillation (MJO). This has implications for the feasibility of data assimilation and real-world initialization for superparameterized weather forecasting. Climate simulation sensitivity tests demonstrate that 400% acceleration of cloud superparameterization is possible by restricting the 32-128 km scale regime without deteriorating the realism of the simulated MJO but the number of cloud resolving model grid columns is discovered to constrain the efficiency of vertical mixing, with consequences for the simulated liquid cloud climatology. Tuning opportunities for next generation accelerated superparameterized climate models are discussed.

Advanced thermal energy management: A thermal test bed and heat pipe simulation

NASA Technical Reports Server (NTRS)

Barile, Ronald G.

1986-01-01

Work initiated on a common-module thermal test simulation was continued, and a second project on heat pipe simulation was begun. The test bed, constructed from surplus Skylab equipment, was modeled and solved for various thermal load and flow conditions. Low thermal load caused the radiator fluid, Coolanol 25, to thicken due to its temperature avoided by using a regenerator-heat-exchanger. Other possible solutions modeled include a radiator heater and shunting heat from the central thermal bus to the radiator. Also, module air temperature can become excessive with high avionics load. A second preoject concerning advanced heat pipe concepts was initiated. A program was written which calculates fluid physical properties, liquid and vapor pressure in the evaporator and condenser, fluid flow rates, and thermal flux. The program is directed to evaluating newer heat pipe wicks and geometries, especially water in an artery surrounded by six vapor channels. Effects of temperature, groove and slot dimensions, and wick properties are reported.

FPGA Based Reconfigurable ATM Switch Test Bed

NASA Technical Reports Server (NTRS)

Chu, Pong P.; Jones, Robert E.

1998-01-01

Various issues associated with "FPGA Based Reconfigurable ATM Switch Test Bed" are presented in viewgraph form. Specific topics include: 1) Network performance evaluation; 2) traditional approaches; 3) software simulation; 4) hardware emulation; 5) test bed highlights; 6) design environment; 7) test bed architecture; 8) abstract sheared-memory switch; 9) detailed switch diagram; 10) traffic generator; 11) data collection circuit and user interface; 12) initial results; and 13) the following conclusions: Advances in FPGA make hardware emulation feasible for performance evaluation, hardware emulation can provide several orders of magnitude speed-up over software simulation; due to the complexity of hardware synthesis process, development in emulation is much more difficult than simulation and requires knowledge in both networks and digital design.

Grain boundary damage evolution and SCC initiation of cold-worked alloy 690 in simulated PWR primary water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhai, Ziqing; Toloczko, Mychailo B.; Kruska, Karen

Long-term grain boundary (GB) damage evolution and stress corrosion crack initiation in alloy 690 are being investigated by constant load tensile testing in high-temperature, simulated PWR primary water. Six commercial alloy 690 heats are being tested in various cold work conditions loaded at their yield stress. This paper reviews the basic test approach and detailed characterizations performed on selected specimens after an exposure time of ~1 year. Intergranular crack nucleation was observed under constant stress in certain highly cold-worked (CW) alloy 690 heats and was found to be associated with the formation of GB cavities. Somewhat surprisingly, the heats mostmore » susceptible to cavity formation and crack nucleation were thermally treated materials with most uniform coverage of small GB carbides. Microstructure, % cold work and applied stress comparisons are made among the alloy 690 heats to better understand the factors influencing GB cavity formation and crack initiation.« less

DCT Trigger in a High-Resolution Test Platform for the Detection of Very Inclined Showers in Pierre Auger Surface Detectors

NASA Astrophysics Data System (ADS)

Szadkowski, Zbigniew; Wiedeński, Michał

2017-06-01

We present first results from a trigger based on the discrete cosine transform (DCT) operating in new front-end boards with a Cyclone V E field-programmable gate array (FPGA) deployed in seven test surface detectors in the Pierre Auger Test Array. The patterns of the ADC traces generated by very inclined showers (arriving at 70° to 90° from the vertical) were obtained from the Auger database and from the CORSIKA simulation package supported by the Auger OffLine event reconstruction platform that gives predicted digitized signal profiles. Simulations for many values of the initial cosmic ray angle of arrival, the shower initialization depth in the atmosphere, the type of particle, and its initial energy gave a boundary on the DCT coefficients used for the online pattern recognition in the FPGA. Preliminary results validated the approach used. We recorded several showers triggered by the DCT for 120 Msamples/s and 160 Msamples/s.

Adaptive Multi-Layer LMS Controller Design and Application to Active Vibration Suppression on a Truss and Proposed Impact Analysis Technique

DTIC Science & Technology

2001-06-01

Setup and Initiation ........................................................ 83 2. Simulation 1 (19 Hz, Y-axis of Node 18, Piezo #2...175 INITIAL DISTRIBUTION LIST ................................................................................... 187 ix...system for the sake of testing and simplicity. The Adaptive Multi-Layered LMS Controller was developed one piece at a time. After initial experimental

Precursor Evolution and Stress Corrosion Cracking Initiation of Cold-Worked Alloy 690 in Simulated Pressurized Water Reactor Primary Water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhai, Ziqing; Toloczko, Mychailo; Kruska, Karen

Stress corrosion crack initiation of two thermally-treated, cold-worked (CW) alloy 690 (UNS N06690) materials was investigated in 360oC simulated PWR primary water using constant load tensile (CLT) tests and blunt notch compact tension (BNCT) tests equipped with direct current potential drop (DCPD) for in-situ detection of cracking. SCC initiation was not detected by DCPD for either the 21% or 31%CW CLT specimens loaded at their yield stress after ~9,220 hours, however intergranular (IG) precursor damage and isolated surface cracks were observed on the specimens. The two 31%CW BNCT specimens loaded at moderate stress intensity after several cyclic loading ramps showedmore » DCPD-indicated crack initiation after 10,400 hours of exposure at constant stress intensity, which was resulted from significant growth of IG cracks. The 21%CW BNCT specimens only exhibited isolated small IG surface cracks and showed no apparent DCPD change throughout the test. Post-test cross-section examinations revealed many grain boundary (GB) nano-cavities in the bulk of all the CLT and BNCT specimens particularly for the 31%CW materials. Cavities were also found along GBs extending to the surface suggesting an important role in crack nucleation. This paper provides an overview of the evolution of GB cavities and discusses their effects on crack initiation in CW alloy 690.« less

The use of NASA GEOS Global Analysis in MM5/WRF Initialization: Current Studies and Future Applications

NASA Technical Reports Server (NTRS)

Pu, Zhao-Xia; Tao, Wei-Kuo

2004-01-01

An effort has been made at NASA/GSFC to use the Goddard Earth Observing system (GEOS) global analysis in generating the initial and boundary conditions for MM5/WRF simulation. This linkage between GEOS global analysis and MM5/WRF models has made possible for a few useful applications. As one of the sample studies, a series of MM5 simulations were conducted to test the sensitivity of initial and boundary conditions to MM5 simulated precipitation over the eastern; USA. Global analyses horn different operational centers (e.g., NCEP, ECMWF, I U ASA/GSFCj were used to provide first guess field and boundary conditions for MM5. Numerical simulations were performed for one- week period over the eastern coast areas of USA. the distribution and quantities of MM5 simulated precipitation were compared. Results will be presented in the workshop. In addition,other applications from recent and future studies will also be addressed.

Two-fluid 2.5D code for simulations of small scale magnetic fields in the lower solar atmosphere

NASA Astrophysics Data System (ADS)

Piantschitsch, Isabell; Amerstorfer, Ute; Thalmann, Julia Katharina; Hanslmeier, Arnold; Lemmerer, Birgit

2015-08-01

Our aim is to investigate magnetic reconnection as a result of the time evolution of magnetic flux tubes in the solar chromosphere. A new numerical two-fluid code was developed, which will perform a 2.5D simulation of the dynamics from the upper convection zone up to the transition region. The code is based on the Total Variation Diminishing Lax-Friedrichs method and includes the effects of ion-neutral collisions, ionisation/recombination, thermal/resistive diffusivity as well as collisional/resistive heating. What is innovative about our newly developed code is the inclusion of a two-fluid model in combination with the use of analytically constructed vertically open magnetic flux tubes, which are used as initial conditions for our simulation. First magnetohydrodynamic (MHD) tests have already shown good agreement with known results of numerical MHD test problems like e.g. the Orszag-Tang vortex test, the Current Sheet test or the Spherical Blast Wave test. Furthermore, the single-fluid approach will also be applied to the initial conditions, in order to compare the different rates of magnetic reconnection in both codes, the two-fluid code and the single-fluid one.

Numerical simulation of Composition B high explosive charge desensitization in gap test assembly after loading by precursor wave

NASA Astrophysics Data System (ADS)

Balagansky, I. A.; Stepanov, A. A.

2016-03-01

Results of numerical research into the desensitization of high explosive charges in water gap test-based experimental assemblies are presented. The experimental data are discussed, and the analysis using ANSYS AUTODYN 14.5 is provided. The desensitization phenomenon is well reproduced in numerical simulation using the JWL EOS and the Lee-Tarver kinetic equation for modeling of the initiation of heterogeneous high explosives with as well as without shock front waves. The analysis of the wave processes occurring during the initiation of the acceptor HE charge has been carried out. Peculiarities of the wave processes in the water gap test assemblies, which can influence the results of sensitivity measurement, have been studied. In particular, it has been established that precursor waves in the walls of the gap test assemblies can influence the detonation transmission distance.

Testing and Analytical Modeling for Purging Process of a Cryogenic Line

NASA Technical Reports Server (NTRS)

Hedayat, A.; Mazurkivich, P. V.; Nelson, M. A.; Majumdar, A. K.

2015-01-01

To gain confidence in developing analytical models of the purging process for the cryogenic main propulsion systems of upper stage, two test series were conducted. Test article, a 3.35m long with the diameter of 20 cm incline line, was filled with liquid (LH2)or gaseous hydrogen (GH2) and then purged with gaseous helium (GHe). Total of 10 tests were conducted. Influences of GHe flow rates and initial temperatures were evaluated. Generalized Fluid System Simulation Program (GFSSP), an in-house general-purpose fluid system analyzer, was utilized to model and simulate selective tests.

A New High-Speed Oil-Free Turbine Engine Rotordynamic Simulator Test Rig

NASA Technical Reports Server (NTRS)

Howard, Samuel A.

2007-01-01

A new test rig has been developed for simulating high-speed turbomachinery rotor systems using Oil-Free foil air bearing technology. Foil air bearings have been used in turbomachinery, primarily air cycle machines, for the past four decades to eliminate the need for oil lubrication. The goal of applying this bearing technology to other classes of turbomachinery has prompted the fabrication of this test rig. The facility gives bearing designers the capability to test potential bearing designs with shafts that simulate the rotating components of a target machine without the high cost of building "make-and-break" hardware. The data collected from this rig can be used to make design changes to the shaft and bearings in subsequent design iterations. This paper describes the new test rig and demonstrates its capabilities through the initial run with a simulated shaft system.

Simulations of the Richtmyer-Meshkov Instability in a two-shock vertical shock tube

NASA Astrophysics Data System (ADS)

Ferguson, Kevin; Olson, Britton; Jacobs, Jeffrey

2017-11-01

Simulations of the Richtmyer-Meshkov Instability (RMI) in a new two-shock vertical shock tube configuration are presented. The simulations are performed using the ARES code at Lawrence-Livermore National Laboratory (LLNL). Two M=1.2 shock waves travel in opposing directions and impact an initially stationary interface formed by sulfur hexaflouride (SF6) and air. The delay between the two shocks is controlled to achieve a prescribed temporal separation in shock wave arrival time. Initial interface perturbations and diffusion profiles are generated in keeping with previously gathered experimental data. The effect of varying the inter-shock delay and initial perturbation structure on instability growth and mixing parameters is examined. Information on the design, construction, and testing of a new two-shock vertical shock tube are also presented.

Quality improvement utilizing in-situ simulation for a dual-hospital pediatric code response team.

PubMed

Yager, Phoebe; Collins, Corey; Blais, Carlene; O'Connor, Kathy; Donovan, Patricia; Martinez, Maureen; Cummings, Brian; Hartnick, Christopher; Noviski, Natan

2016-09-01

Given the rarity of in-hospital pediatric emergency events, identification of gaps and inefficiencies in the code response can be difficult. In-situ, simulation-based medical education programs can identify unrecognized systems-based challenges. We hypothesized that developing an in-situ, simulation-based pediatric emergency response program would identify latent inefficiencies in a complex, dual-hospital pediatric code response system and allow rapid intervention testing to improve performance before implementation at an institutional level. Pediatric leadership from two hospitals with a shared pediatric code response team employed the Institute for Healthcare Improvement's (IHI) Breakthrough Model for Collaborative Improvement to design a program consisting of Plan-Do-Study-Act cycles occurring in a simulated environment. The objectives of the program were to 1) identify inefficiencies in our pediatric code response; 2) correlate to current workflow; 3) employ an iterative process to test quality improvement interventions in a safe environment; and 4) measure performance before actual implementation at the institutional level. Twelve dual-hospital, in-situ, simulated, pediatric emergencies occurred over one year. The initial simulated event allowed identification of inefficiencies including delayed provider response, delayed initiation of cardiopulmonary resuscitation (CPR), and delayed vascular access. These gaps were linked to process issues including unreliable code pager activation, slow elevator response, and lack of responder familiarity with layout and contents of code cart. From first to last simulation with multiple simulated process improvements, code response time for secondary providers coming from the second hospital decreased from 29 to 7 min, time to CPR initiation decreased from 90 to 15 s, and vascular access obtainment decreased from 15 to 3 min. Some of these simulated process improvements were adopted into the institutional response while others continue to be trended over time for evidence that observed changes represent a true new state of control. Utilizing the IHI's Breakthrough Model, we developed a simulation-based program to 1) successfully identify gaps and inefficiencies in a complex, dual-hospital, pediatric code response system and 2) provide an environment in which to safely test quality improvement interventions before institutional dissemination. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Simulations for the Assessment of Counselling Skills.

ERIC Educational Resources Information Center

Smit, Gertrude N.; van der Molen, Henk T.

1996-01-01

A Dutch undergraduate course in professional counseling skills uses simulation to test students' ability to conduct an initial client interview, using standardized case histories. A study investigated the effectiveness of the method with 160 course participants, 77 non-participants, and 12 professional counselors and found it useful for…

Investigation of thermolytic hydrogen generation rate of tank farm simulated and actual waste

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martino, C.; Newell, D.; Woodham, W.

To support resolution of Potential Inadequacies in the Safety Analysis for the Savannah River Site (SRS) Tank Farm, Savannah River National Laboratory conducted research to determine the thermolytic hydrogen generation rate (HGR) with simulated and actual waste. Gas chromatography methods were developed and used with air-purged flow systems to quantify hydrogen generation from heated simulated and actual waste at rates applicable to the Tank Farm Documented Safety Analysis (DSA). Initial simulant tests with a simple salt solution plus sodium glycolate demonstrated the behavior of the test apparatus by replicating known HGR kinetics. Additional simulant tests with the simple salt solutionmore » excluding organics apart from contaminants provided measurement of the detection and quantification limits for the apparatus with respect to hydrogen generation. Testing included a measurement of HGR on actual SRS tank waste from Tank 38. A final series of measurements examined HGR for a simulant with the most common SRS Tank Farm organics at temperatures up to 140 °C. The following conclusions result from this testing.« less

Comparison of a 3-D DEM simulation with MRI data

NASA Astrophysics Data System (ADS)

Ng, Tang-Tat; Wang, Changming

2001-04-01

This paper presents a comparison of a granular material studied experimentally and numerically. Simple shear tests were performed inside the magnetic core of magnetic resonance imaging (MRI) equipment. Spherical pharmaceutical pills were used as the granular material, with each pill's centre location determined by MRI. These centre locations in the initial assembly were then used as the initial configuration in the numerical simulation using the discrete element method. The contact properties between pharmaceutical pills used in the numerical simulation were obtained experimentally. The numerical predication was compared with experimental data at both macroscopic and microscopic levels. Good agreement was found at both levels.

Optimal timing of viral load monitoring during pregnancy to predict viraemia at delivery in HIV-infected women initiating ART in South Africa: a simulation study.

PubMed

Lesosky, Maia; Glass, Tracy; Mukonda, Elton; Hsiao, Nei-Yuan; Abrams, Elaine J; Myer, Landon

2017-11-01

HIV viral load (VL) monitoring is a central tool to evaluate ART effectiveness and transmission risk. There is a global movement to expand VL monitoring following recent recommendations from the World Health Organization (WHO), but there has been little research into VL monitoring in pregnant women. We investigated one important question in this area: when and how frequently VL should be monitored in women initiating ART during pregnancy to predict VL at the time of delivery in a simulated South African population. We developed a mathematical model simulating VL from conception through delivery using VL data from the Maternal and Child Health - Antiretroviral Therapy (MCH-ART) cohort. VL was modelled based on three major compartments: pre-ART VL, viral decay immediately after ART initiation and viral maintenance (including viral suppression and viraemic episodes). Using this simulation, we examined the performance of various VL monitoring schema in predicting elevated VL at delivery. If WHO guidelines for non-pregnant adults were used, the majority of HIV-infected pregnant women (69%) would not receive a VL test during pregnancy. Most models that based VL monitoring in pregnancy on the time elapsed since ART initiation (regardless of gestation) performed poorly (sensitivity <50%); models that based VL measures in pregnancy on the woman's gestation (regardless of time on ART) appeared to perform better overall (sensitivity >60%). Across all permutations, inclusion of pre-ART VL values had a negligible impact on predictive performance (improving test sensitivity and specificity <6%). Performance of VL monitoring in predicting VL at delivery generally improved at later gestations, with the best performing option a single VL measure at 36 weeks' gestation. Development and evaluation of a novel simulation model suggests that strategies to measure VL relative to gestational age may be more useful than strategies relative to duration on ART, in women initiating ART during pregnancy, supporting better integration of maternal and HIV health services. Testing turnaround times require careful consideration, and point-of-care VL testing may be the best approach for measuring VL at delivery. Broadening the scope of this simulation model in the light of current scale up of VL monitoring in high burden countries is important. © 2017 The Authors. Journal of the International AIDS Society published by John Wiley & sons Ltd on behalf of the International AIDS Society.

A Self-Alignment Algorithm for SINS Based on Gravitational Apparent Motion and Sensor Data Denoising

PubMed Central

Liu, Yiting; Xu, Xiaosu; Liu, Xixiang; Yao, Yiqing; Wu, Liang; Sun, Jin

2015-01-01

Initial alignment is always a key topic and difficult to achieve in an inertial navigation system (INS). In this paper a novel self-initial alignment algorithm is proposed using gravitational apparent motion vectors at three different moments and vector-operation. Simulation and analysis showed that this method easily suffers from the random noise contained in accelerometer measurements which are used to construct apparent motion directly. Aiming to resolve this problem, an online sensor data denoising method based on a Kalman filter is proposed and a novel reconstruction method for apparent motion is designed to avoid the collinearity among vectors participating in the alignment solution. Simulation, turntable tests and vehicle tests indicate that the proposed alignment algorithm can fulfill initial alignment of strapdown INS (SINS) under both static and swinging conditions. The accuracy can either reach or approach the theoretical values determined by sensor precision under static or swinging conditions. PMID:25923932

Simulation and Analysis of Converging Shock Wave Test Problems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramsey, Scott D.; Shashkov, Mikhail J.

2012-06-21

Results and analysis pertaining to the simulation of the Guderley converging shock wave test problem (and associated code verification hydrodynamics test problems involving converging shock waves) in the LANL ASC radiation-hydrodynamics code xRAGE are presented. One-dimensional (1D) spherical and two-dimensional (2D) axi-symmetric geometric setups are utilized and evaluated in this study, as is an instantiation of the xRAGE adaptive mesh refinement capability. For the 2D simulations, a 'Surrogate Guderley' test problem is developed and used to obviate subtleties inherent to the true Guderley solution's initialization on a square grid, while still maintaining a high degree of fidelity to the originalmore » problem, and minimally straining the general credibility of associated analysis and conclusions.« less

MAGI: many-component galaxy initializer

NASA Astrophysics Data System (ADS)

Miki, Yohei; Umemura, Masayuki

2018-04-01

Providing initial conditions is an essential procedure for numerical simulations of galaxies. The initial conditions for idealized individual galaxies in N-body simulations should resemble observed galaxies and be dynamically stable for time-scales much longer than their characteristic dynamical times. However, generating a galaxy model ab initio as a system in dynamical equilibrium is a difficult task, since a galaxy contains several components, including a bulge, disc, and halo. Moreover, it is desirable that the initial-condition generator be fast and easy to use. We have now developed an initial-condition generator for galactic N-body simulations that satisfies these requirements. The developed generator adopts a distribution-function-based method, and it supports various kinds of density models, including custom-tabulated inputs and the presence of more than one disc. We tested the dynamical stability of systems generated by our code, representing early- and late-type galaxies, with N = 2097 152 and 8388 608 particles, respectively, and we found that the model galaxies maintain their initial distributions for at least 1 Gyr. The execution times required to generate the two models were 8.5 and 221.7 seconds, respectively, which is negligible compared to typical execution times for N-body simulations. The code is provided as open-source software and is publicly and freely available at https://bitbucket.org/ymiki/magi.

Hysteresis in simulations of malaria transmission

NASA Astrophysics Data System (ADS)

Yamana, Teresa K.; Qiu, Xin; Eltahir, Elfatih A. B.

2017-10-01

Malaria transmission is a complex system and in many parts of the world is closely related to climate conditions. However, studies on environmental determinants of malaria generally consider only concurrent climate conditions and ignore the historical or initial conditions of the system. Here, we demonstrate the concept of hysteresis in malaria transmission, defined as non-uniqueness of the relationship between malaria prevalence and concurrent climate conditions. We show the dependence of simulated malaria transmission on initial prevalence and the initial level of human immunity in the population. Using realistic time series of environmental variables, we quantify the effect of hysteresis in a modeled population. In a set of numerical experiments using HYDREMATS, a field-tested mechanistic model of malaria transmission, the simulated maximum malaria prevalence depends on both the initial prevalence and the initial level of human immunity in the population. We found the effects of initial conditions to be of comparable magnitude to the effects of interannual variability in environmental conditions in determining malaria prevalence. The memory associated with this hysteresis effect is longer in high transmission settings than in low transmission settings. Our results show that efforts to simulate and forecast malaria transmission must consider the exposure history of a location as well as the concurrent environmental drivers.

ADVANCED UTILITY SIMULATION MODEL, REPORT OF SENSITIVITY TESTING, CALIBRATION, AND MODEL OUTPUT COMPARISONS (VERSION 3.0) TAPE

EPA Science Inventory

The report is one of 11 in a series describing the initial development of the Advanced Utility Simulation Model (AUSM) by the Universities Research Group on Energy (URGE) and its continued development by the Science Applications International Corporation (SAIC) research team. The...

Validation of an Active Gear, Flexible Aircraft Take-off and Landing analysis (AGFATL)

NASA Technical Reports Server (NTRS)

Mcgehee, J. R.

1984-01-01

The results of an analytical investigation using a computer program for active gear, flexible aircraft take off and landing analysis (AGFATL) are compared with experimental data from shaker tests, drop tests, and simulated landing tests to validate the AGFATL computer program. Comparison of experimental and analytical responses for both passive and active gears indicates good agreement for shaker tests and drop tests. For the simulated landing tests, the passive and active gears were influenced by large strut binding friction forces. The inclusion of these undefined forces in the analytical simulations was difficult, and consequently only fair to good agreement was obtained. An assessment of the results from the investigation indicates that the AGFATL computer program is a valid tool for the study and initial design of series hydraulic active control landing gear systems.

Liquid oxygen (LO2) propellant conditioning concept testing

NASA Technical Reports Server (NTRS)

Perry, Gretchen L. E.; Orth, Michael S.; Mehta, Gopal K.

1993-01-01

Testing of a simplified LO2 propellant conditioning concept for future expendable launch vehicles is discussed. Four different concepts are being investigated: no-bleed, low-bleed, use of a recirculation line, and He bubbling. A full-scale test article, which is a facsimile of a propellant feed duct with an attached section to simulate heat input from an LO2 turbopump, is to be tested at the Cold Flow Facility of the Marshall Space Flight Center West Test Area. Work to date includes: design and fabrication of the test article, design of the test facility and initial fabrication, development of a test matrix and test procedures, initial predictions of test output, and heat leak calibration and heat exchanger tests on the test articles.

A randomised controlled trial of extended immersion in multi-method continuing simulation to prepare senior medical students for practice as junior doctors

PubMed Central

2014-01-01

Background Many commencing junior doctors worldwide feel ill-prepared to deal with their new responsibilities, particularly prescribing. Simulation has been widely utilised in medical education, but the use of extended multi-method simulation to emulate the junior doctor experience has rarely been reported. Methods A randomised controlled trial compared students who underwent two, week-long, extended simulations, several months apart (Intervention), with students who attended related workshops and seminars alone (Control), for a range of outcome measures. Results Eighty-four third year students in a graduate-entry medical program were randomised, and 82 completed the study. At the end of the first week, Intervention students scored a mean of 75% on a prescribing test, compared with 70% for Control students (P = 0.02) and Intervention teams initiated cardiac compressions a mean of 29.1 seconds into a resuscitation test scenario, compared with 70.1 seconds for Control teams (P < 0.01). At the beginning of the second week, an average of nine months later, a significant difference was maintained in relation to the prescribing test only (78% vs 70%, P < 0.01). At the end of the second week, significant Intervention vs Control differences were seen on knowledge and reasoning tests, a further prescribing test (71% vs 63% [P < 0.01]) and a paediatric resuscitation scenario test (252 seconds to initiation of fluid resuscitation vs 339 seconds [P = 0.05]). Conclusions The study demonstrated long-term retention of improved prescribing skills, and an immediate effect on knowledge acquisition, reasoning and resuscitation skills, from contextualising learning activities through extended multi-method simulation. PMID:24886098

Pilot-in-the-Loop CFD Method Development

DTIC Science & Technology

2014-06-16

CFD analysis. Coupled simulations will be run at PSU on the COCOA -4 cluster, a high performance computing cluster. The CRUNCH CFD software has...been installed on the COCOA -4 servers and initial software tests are being conducted. Initial efforts will use the Generic Frigate Shape SFS-2 to

Finite Element Simulation of Three Full-Scale Crash Tests for Cessna 172 Aircraft

NASA Technical Reports Server (NTRS)

Mason, Brian H.; Warren, Jerry E., Jr.

2017-01-01

The NASA Emergency Locator Transmitter Survivability and Reliability (ELT-SAR) project was initiated in 2013 to assess the crash performance standards for the next generation of emergency locator transmitter (ELT) systems. Three Cessna 172 aircraft were acquired to perform crash testing at NASA Langley Research Center's Landing and Impact Research Facility. Full-scale crash tests were conducted in the summer of 2015 and each test article was subjected to severe, but survivable, impact conditions including a flare-to-stall during emergency landing, and two controlled-flight-into-terrain scenarios. Full-scale finite element analyses were performed using a commercial explicit solver, ABAQUS. The first test simulated impacting a concrete surface represented analytically by a rigid plane. Tests 2 and 3 simulated impacting a dirt surface represented analytically by an Eulerian grid of brick elements using a Mohr-Coulomb material model. The objective of this paper is to summarize the test and analysis results for the three full-scale crash tests. Simulation models of the airframe which correlate well with the tests are needed for future studies of alternate ELT mounting configurations.

Distributed Simulation as a modelling tool for the development of a simulation-based training programme for cardiovascular specialties.

PubMed

Kelay, Tanika; Chan, Kah Leong; Ako, Emmanuel; Yasin, Mohammad; Costopoulos, Charis; Gold, Matthew; Kneebone, Roger K; Malik, Iqbal S; Bello, Fernando

2017-01-01

Distributed Simulation is the concept of portable, high-fidelity immersive simulation. Here, it is used for the development of a simulation-based training programme for cardiovascular specialities. We present an evidence base for how accessible, portable and self-contained simulated environments can be effectively utilised for the modelling, development and testing of a complex training framework and assessment methodology. Iterative user feedback through mixed-methods evaluation techniques resulted in the implementation of the training programme. Four phases were involved in the development of our immersive simulation-based training programme: ( 1) initial conceptual stage for mapping structural criteria and parameters of the simulation training framework and scenario development ( n  = 16), (2) training facility design using Distributed Simulation , (3) test cases with clinicians ( n  = 8) and collaborative design, where evaluation and user feedback involved a mixed-methods approach featuring (a) quantitative surveys to evaluate the realism and perceived educational relevance of the simulation format and framework for training and (b) qualitative semi-structured interviews to capture detailed feedback including changes and scope for development. Refinements were made iteratively to the simulation framework based on user feedback, resulting in (4) transition towards implementation of the simulation training framework, involving consistent quantitative evaluation techniques for clinicians ( n  = 62). For comparative purposes, clinicians' initial quantitative mean evaluation scores for realism of the simulation training framework, realism of the training facility and relevance for training ( n  = 8) are presented longitudinally, alongside feedback throughout the development stages from concept to delivery, including the implementation stage ( n  = 62). Initially, mean evaluation scores fluctuated from low to average, rising incrementally. This corresponded with the qualitative component, which augmented the quantitative findings; trainees' user feedback was used to perform iterative refinements to the simulation design and components (collaborative design), resulting in higher mean evaluation scores leading up to the implementation phase. Through application of innovative Distributed Simulation techniques, collaborative design, and consistent evaluation techniques from conceptual, development, and implementation stages, fully immersive simulation techniques for cardiovascular specialities are achievable and have the potential to be implemented more broadly.

Development of the CELSS emulator at NASA. Johnson Space Center

NASA Technical Reports Server (NTRS)

Cullingford, Hatice S.

1990-01-01

The Closed Ecological Life Support System (CELSS) Emulator is under development. It will be used to investigate computer simulations of integrated CELSS operations involving humans, plants, and process machinery. Described here is Version 1.0 of the CELSS Emulator that was initiated in 1988 on the Johnson Space Center (JSC) Multi Purpose Applications Console Test Bed as the simulation framework. The run model of the simulation system now contains a CELSS model called BLSS. The CELSS simulator empowers us to generate model data sets, store libraries of results for further analysis, and also display plots of model variables as a function of time. The progress of the project is presented with sample test runs and simulation display pages.

Flight testing and simulation of an F-15 airplane using throttles for flight control

NASA Technical Reports Server (NTRS)

Burcham, Frank W., Jr.; Maine, Trindel; Wolf, Thomas

1992-01-01

Flight tests and simulation studies using the throttles of an F-15 airplane for emergency flight control have been conducted at the NASA Dryden Flight Research Facility. The airplane and the simulation are capable of extended up-and-away flight, using only throttles for flight path control. Initial simulation results showed that runway landings using manual throttles-only control were difficult, but possible with practice. Manual approaches flown in the airplane were much more difficult, indicating a significant discrepancy between flight and simulation. Analysis of flight data and development of improved simulation models that resolve the discrepancy are discussed. An augmented throttle-only control system that controls bank angle and flight path with appropriate feedback parameters has also been developed, evaluated in simulations, and is planned for flight in the F-15.

Nuclear Thermal Rocket Element Environmental Simulator (NTREES) Upgrade Activities

NASA Technical Reports Server (NTRS)

Emrich, William J. Jr.; Moran, Robert P.; Pearson, J. Boise

2012-01-01

To support the on-going nuclear thermal propulsion effort, a state-of-the-art non nuclear experimental test setup has been constructed to evaluate the performance characteristics of candidate fuel element materials and geometries in representative environments. The facility to perform this testing is referred to as the Nuclear Thermal Rocket Element Environment Simulator (NTREES). This device can simulate the environmental conditions (minus the radiation) to which nuclear rocket fuel components will be subjected during reactor operation. Test articles mounted in the simulator are inductively heated in such a manner so as to accurately reproduce the temperatures and heat fluxes which would normally occur as a result of nuclear fission and would be exposed to flowing hydrogen. Initial testing of a somewhat prototypical fuel element has been successfully performed in NTREES and the facility has now been shutdown to allow for an extensive reconfiguration of the facility which will result in a significant upgrade in its capabilities

Development and mechanical properties of construction materials from lunar simulants

NASA Technical Reports Server (NTRS)

Desai, Chandra S.

1990-01-01

The development of construction materials such as concrete from lunar soils without the use of water requires a different methodology than that used for conventional terrestrial concrete. Currently, this research involves two aspects: (1) liquefaction of lunar simulants with various additives in a furnace so as to produce a construction material like an intermediate ceramic; and (2) cyclic loading of simulant with different initial vacuums and densities with respect to the theoretical maximum densities (TMD). In both cases, bending, triaxial compression, extension, and hydrostatic tests will be performed to define the stress-strain strength response of the resulting materials. In the case of the intermediate ceramic, bending and available multiaxial test devices will be used, while for the compacted case, tests will be performed directly in the new device. The tests will be performed by simulating in situ confining conditions. A preliminary review of high-purity metal is also conducted.

Heave-pitch-roll analysis and testing of air cushion landing systems

NASA Technical Reports Server (NTRS)

Boghani, A. B.; Captain, K. M.; Wormley, D. N.

1978-01-01

The analytical tools (analysis and computer simulation) needed to explain and predict the dynamic operation of air cushion landing systems (ACLS) is described. The following tasks were performed: the development of improved analytical models for the fan and the trunk; formulation of a heave pitch roll analysis for the complete ACLS; development of a general purpose computer simulation to evaluate landing and taxi performance of an ACLS equipped aircraft; and the verification and refinement of the analysis by comparison with test data obtained through lab testing of a prototype cushion. Demonstration of simulation capabilities through typical landing and taxi simulation of an ACLS aircraft are given. Initial results show that fan dynamics have a major effect on system performance. Comparison with lab test data (zero forward speed) indicates that the analysis can predict most of the key static and dynamic parameters (pressure, deflection, acceleration, etc.) within a margin of a 10 to 25 percent.

A method for validation of finite element forming simulation on basis of a pointwise comparison of distance and curvature

NASA Astrophysics Data System (ADS)

Dörr, Dominik; Joppich, Tobias; Schirmaier, Fabian; Mosthaf, Tobias; Kärger, Luise; Henning, Frank

2016-10-01

Thermoforming of continuously fiber reinforced thermoplastics (CFRTP) is ideally suited to thin walled and complex shaped products. By means of forming simulation, an initial validation of the producibility of a specific geometry, an optimization of the forming process and the prediction of fiber-reorientation due to forming is possible. Nevertheless, applied methods need to be validated. Therefor a method is presented, which enables the calculation of error measures for the mismatch between simulation results and experimental tests, based on measurements with a conventional coordinate measuring device. As a quantitative measure, describing the curvature is provided, the presented method is also suitable for numerical or experimental sensitivity studies on wrinkling behavior. The applied methods for forming simulation, implemented in Abaqus explicit, are presented and applied to a generic geometry. The same geometry is tested experimentally and simulation and test results are compared by the proposed validation method.

Analysis of the OPERA 15-pin experiment with SABRE-2P. [LMFBR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rose, S.D.; Carbajo, J.J.

The OPERA (Out-of-Pile Expulsion and Reentry Apparatus) experiment simulates the initial phase of a pump coastdown without scram of a liquid-metal fast breeder reactor, specifically the Fast Flux Test Facility. The test section is a 15-pin 60/sup 0/ triangular sector designed to simulate a full-size 61-pin hexagonal bundle. A previous study indicates this to be an adequate simulation. In this paper, experimental results from the OPERA 15-pin experiment performed at ANL in 1982 are compared to analytical calculations obtained with the SABRE-2P code at ORNL.

Benchmark tests for a Formula SAE Student car prototyping

NASA Astrophysics Data System (ADS)

Mariasiu, Florin

2011-12-01

Aerodynamic characteristics of a vehicle are important elements in its design and construction. A low drag coefficient brings significant fuel savings and increased engine power efficiency. In designing and developing vehicles trough computer simulation process to determine the vehicles aerodynamic characteristics are using dedicated CFD (Computer Fluid Dynamics) software packages. However, the results obtained by this faster and cheaper method, are validated by experiments in wind tunnels tests, which are expensive and were complex testing equipment are used in relatively high costs. Therefore, the emergence and development of new low-cost testing methods to validate CFD simulation results would bring great economic benefits for auto vehicles prototyping process. This paper presents the initial development process of a Formula SAE Student race-car prototype using CFD simulation and also present a measurement system based on low-cost sensors through which CFD simulation results were experimentally validated. CFD software package used for simulation was Solid Works with the FloXpress add-on and experimental measurement system was built using four piezoresistive force sensors FlexiForce type.

Nuclear Thermal Rocket Element Environmental Simulator (NTREES) Phase II Upgrade Activities

NASA Technical Reports Server (NTRS)

Emrich, William J.; Moran, Robert P.; Pearson, J. Bose

2013-01-01

To support the on-going nuclear thermal propulsion effort, a state-of-the-art non nuclear experimental test setup has been constructed to evaluate the performance characteristics of candidate fuel element materials and geometries in representative environments. The facility to perform this testing is referred to as the Nuclear Thermal Rocket Element Environment Simulator (NTREES). This device can simulate the environmental conditions (minus the radiation) to which nuclear rocket fuel components will be subjected during reactor operation. Test articles mounted in the simulator are inductively heated in such a manner so as to accurately reproduce the temperatures and heat fluxes which would normally occur as a result of nuclear fission and would be exposed to flowing hydrogen. Initial testing of a somewhat prototypical fuel element has been successfully performed in NTREES and the facility has now been shutdown to allow for an extensive reconfiguration of the facility which will result in a significant upgrade in its capabilities. Keywords: Nuclear Thermal Propulsion, Simulator

Series-Bosch Technology for Oxygen Recovery During Lunar or Martian Surface Missions

NASA Technical Reports Server (NTRS)

Abney, Morgan B.; Mansell, J. Matthew; Rabenberg, Ellen; Stanley, Christine M.; Edmunson, Jennifer; Alleman, James E.; Chen, Kevin; Dumez, Sam

2014-01-01

Long-duration surface missions to the Moon or Mars will require life support systems that maximize resource recovery to minimize resupply from Earth. To address this need, NASA previously proposed a Series-Bosch (S-Bosch) oxygen recovery system, based on the Bosch process, which can theoretically recover 100% of the oxygen from metabolic carbon dioxide. Bosch processes have the added benefits of the potential to recover oxygen from atmospheric carbon dioxide and the use of regolith materials as catalysts, thereby eliminating the need for catalyst resupply from Earth. In 2012, NASA completed an initial design for an S-Bosch development test stand that incorporates two catalytic reactors in series including a Reverse Water-Gas Shift (RWGS) Reactor and a Carbon Formation Reactor (CFR). In 2013, fabrication of system components, with the exception of a CFR, and assembly of the test stand was initiated. Stand-alone testing of the RWGS reactor was completed to compare performance with design models. Continued testing of Lunar and Martian regolith simulants provided sufficient data to design a CFR intended to utilize these materials as catalysts. Finally, a study was conducted to explore the possibility of producing bricks from spent regolith catalysts. The results of initial demonstration testing of the RWGS reactor, results of continued catalyst performance testing of regolith simulants, and results of brick material properties testing are reported. Additionally, design considerations for a regolith-based CFR are discussed.

Series-Bosch Technology for Oxygen Recovery During Lunar or Martian Surface Missions

NASA Technical Reports Server (NTRS)

Abney, Morgan B.; Mansell, James M.; Stanley, Christine; Edmunson, Jennifer; Dumez, Samuel; Chen, Kevin; Alleman, James E.

2014-01-01

Long-duration surface missions to the Moon or Mars will require life support systems that maximize resource recovery to minimize resupply from Earth. To address this need, NASA previously proposed a Series-Bosch (S-Bosch) oxygen recovery system, based on the Bosch process, which can theoretically recover 100% of the oxygen from metabolic carbon dioxide. Bosch processes have the added benefits of the potential to recover oxygen from atmospheric carbon dioxide and the use of regolith materials as catalysts, thereby eliminating the need for catalyst resupply from Earth. In 2012, NASA completed an initial design for an S-Bosch development test stand that incorporates two catalytic reactors in series including a Reverse Water-Gas Shift (RWGS) Reactor and a Carbon Formation Reactor (CFR). In 2013, fabrication of system components, with the exception of a CFR, and assembly of the test stand was initiated. Stand-alone testing of the RWGS reactor was completed to compare performance with design models. Continued testing of Lunar and Martian regolith simulants provided sufficient data to design a CFR intended to utilize these materials as catalysts. Finally, a study was conducted to explore the possibility of producing bricks from spend regolith catalysts. The results of initial demonstration testing of the RWGS reactor, results of continued catalyst performance testing of regolith simulants, and results of brick material properties testing are reported. Additionally, design considerations for a regolith-based CFR are discussed.

EMISSIONS FROM BURNING CABINET MAKING SCRAPS

EPA Science Inventory

The report gives results of an initial determination of differences in missions when burning ordinary cordwood compared to kitchen cabinet making scraps. he tests were performed in an instrumented woodstove testing laboratory on a stove that simulated units observed in use at a k...

Validation and Simulation of Ares I Scale Model Acoustic Test - 2 - Simulations at 5 Foot Elevation for Evaluation of Launch Mount Effects

NASA Technical Reports Server (NTRS)

Strutzenberg, Louise L.; Putman, Gabriel C.

2011-01-01

The Ares I Scale Model Acoustics Test (ASMAT) is a series of live-fire tests of scaled rocket motors meant to simulate the conditions of the Ares I launch configuration. These tests have provided a well documented set of high fidelity measurements useful for validation including data taken over a range of test conditions and containing phenomena like Ignition Over-Pressure and water suppression of acoustics. Expanding from initial simulations of the ASMAT setup in a held down configuration, simulations have been performed using the Loci/CHEM computational fluid dynamics software for ASMAT tests of the vehicle at 5 ft. elevation (100 ft. real vehicle elevation) with worst case drift in the direction of the launch tower. These tests have been performed without water suppression and have compared the acoustic emissions for launch structures with and without launch mounts. In addition, simulation results have also been compared to acoustic and imagery data collected from similar live-fire tests to assess the accuracy of the simulations. Simulations have shown a marked change in the pattern of emissions after removal of the launch mount with a reduction in the overall acoustic environment experienced by the vehicle and the formation of highly directed acoustic waves moving across the platform deck. Comparisons of simulation results to live-fire test data showed good amplitude and temporal correlation and imagery comparisons over the visible and infrared wavelengths showed qualitative capture of all plume and pressure wave evolution features.

Methodological approaches to conducting pilot and proof tests on reverse-osmosis systems: Results of comparative studies

NASA Astrophysics Data System (ADS)

Panteleev, A. A.; Bobinkin, V. V.; Larionov, S. Yu.; Ryabchikov, B. E.; Smirnov, V. B.; Shapovalov, D. A.

2017-10-01

When designing large-scale water-treatment plants based on reverse-osmosis systems, it is proposed to conduct experimental-industrial or pilot tests for validated simulation of the operation of the equipment. It is shown that such tests allow establishing efficient operating conditions and characteristics of the plant under design. It is proposed to conduct pilot tests of the reverse-osmosis systems on pilot membrane plants (PMPs) and test membrane plants (TMPs). The results of a comparative experimental study of pilot and test membrane plants are exemplified by simulating the operating parameters of the membrane elements of an industrial plant. It is concluded that the reliability of the data obtained on the TMP may not be sufficient to design industrial water-treatment plants, while the PMPs are capable of providing reliable data that can be used for full-scale simulation of the operation of industrial reverse-osmosis systems. The test membrane plants allow simulation of the operating conditions of individual industrial plant systems; therefore, potential areas of their application are shown. A method for numerical calculation and experimental determination of the true selectivity and the salt passage are proposed. An expression has been derived that describes the functional dependence between the observed and true salt passage. The results of the experiments conducted on a test membrane plant to determine the true value of the salt passage of a reverse-osmosis membrane are exemplified by magnesium sulfate solution at different initial operating parameters. It is shown that the initial content of a particular solution component has a significant effect on the change in the true salt passage of the membrane.

Progressive Damage Analyses of Skin/Stringer Debonding

NASA Technical Reports Server (NTRS)

Daville, Carlos G.; Camanho, Pedro P.; deMoura, Marcelo F.

2004-01-01

The debonding of skin/stringer constructions is analyzed using a step-by-step simulation of material degradation based on strain softening decohesion elements and a ply degradation procedure. Decohesion elements with mixed-mode capability are placed at the interface between the skin and the flange to simulate the initiation and propagation of the delamination. In addition, the initiation and accumulation of fiber failure and matrix damage is modeled using Hashin-type failure criteria and their corresponding material degradation schedules. The debonding predictions using simplified three-dimensional models correlate well with test results.

Engineering sciences area and module performance and failure analysis area

NASA Technical Reports Server (NTRS)

Ross, R. G., Jr.; Runkle, L. D.

1982-01-01

Photovoltaic-array/power-conditioner interface studies are updated. An experiment conducted to evaluate different operating-point strategies, such as constant voltage and pilot cells, and to determine array energy losses when the array is operated off the maximum power points is described. Initial results over a test period of three and a half weeks showed a 2% energy loss when the array is operated at a fixed voltage. Degraded-array studies conducted at NE RES that used a range of simulated common types of degraded I-V curves are reviewed. The instrumentation installed at the JPL field-test site to obtain the irradiance data was described. Experiments using an optical filter to adjust the spectral irradiance of the large-area pulsed solar simulator (LAPSS) to AM1.5 are described. Residential-array research activity is reviewed. Voltage isolation test results are described. Experiments performed on one type of module to determine the relationship between leakage current and temperature are reviewed. An encapsulated-cell testing approach is explained. The test program, data reduction methods, and initial results of long-duration module testing are described.

Testing and Analytical Modeling for Purging Process of a Cryogenic Line

NASA Technical Reports Server (NTRS)

Hedayat, A.; Mazurkivich, P. V.; Nelson, M. A.; Majumdar, A. K.

2015-01-01

To gain confidence in developing analytical models of the purging process for the cryogenic main propulsion systems of upper stage, two test series were conducted. The test article, a 3.35 m long with the diameter of 20 cm incline line, was filled with liquid or gaseous hydrogen and then purged with gaseous helium (GHe). Total of 10 tests were conducted. The influences of GHe flow rates and initial temperatures were evaluated. The Generalized Fluid System Simulation Program (GFSSP), an in-house general-purpose fluid system analyzer computer program, was utilized to model and simulate selective tests. The test procedures, modeling descriptions, and the results are presented in the following sections.

Testing and Analytical Modeling for Purging Process of a Cryogenic Line

NASA Technical Reports Server (NTRS)

Hedayat, A.; Mazurkivich, P. V.; Nelson, M. A.; Majumdar, A. K.

2013-01-01

To gain confidence in developing analytical models of the purging process for the cryogenic main propulsion systems of upper stage, two test series were conducted. The test article, a 3.35 m long with the diameter of 20 cm incline line, was filled with liquid or gaseous hydrogen and then purged with gaseous helium (GHe). Total of 10 tests were conducted. The influences of GHe flow rates and initial temperatures were evaluated. The Generalized Fluid System Simulation Program (GFSSP), an in-house general-purpose fluid system analyzer computer program, was utilized to model and simulate selective tests. The test procedures, modeling descriptions, and the results are presented in the following sections.

Testing and modeling of PBX-9591 shock initiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lam, Kim; Foley, Timothy; Novak, Alan

2010-01-01

This paper describes an ongoing effort to develop a detonation sensitivity test for PBX-9501 that is suitable for studying pristine and damaged HE. The approach involves testing and comparing the sensitivities of HE pressed to various densities and those of pre-damaged samples with similar porosities. The ultimate objectives are to understand the response of pre-damaged HE to shock impacts and to develop practical computational models for use in system analysis codes for HE safety studies. Computer simulation with the CTH shock physics code is used to aid the experimental design and analyze the test results. In the calculations, initiation andmore » growth or failure of detonation are modeled with the empirical HVRB model. The historical LANL SSGT and LSGT were reviewed and it was determined that a new, modified gap test be developed to satisfy the current requirements. In the new test, the donor/spacer/acceptor assembly is placed in a holder that is designed to work with fixtures for pre-damaging the acceptor sample. CTH simulations were made of the gap test with PBX-9501 samples pressed to three different densities. The calculated sensitivities were validated by test observations. The agreement between the computed and experimental critical gap thicknesses, ranging from 9 to 21 mm under various test conditions, is well within 1 mm. These results show that the numerical modeling is a valuable complement to the experimental efforts in studying and understanding shock initiation of PBX-9501.« less

Novel approach for beacon formation through simulated turbulence: initial lab-test results

NASA Astrophysics Data System (ADS)

Khizhnyak, A.; Markov, V.; Tomov, I.; Wu, F.

2010-02-01

In this paper we report the results of the analysis and experimental modeling of the target-in-the-loop (TIL) approach that is used to form a localized beacon for a laser beam propagating through turbulent atmosphere. The analogy between the TIL system and the laser cavity has been used here to simulate the process shaping the laser beacon on a remote image-resolved target with rough surface. The TIL breadboard was integrated and used for laboratory modeling of the proposed approach. This breadboard allowed to simulate the TIL arrangement with a rough-surface target and laser beam propagation through the turbulent atmospheric layer. Here we present the initial results of the performed studies.

Customer Communication Document

NASA Technical Reports Server (NTRS)

2009-01-01

This procedure communicates to the Customers of the Automation, Robotics and Simulation Division (AR&SD) Dynamics Systems Test Branch (DSTB) how to obtain services of the Six-Degrees-Of-Freedom Dynamic Test System (SDTS). The scope includes the major communication documents between the SDTS and its Customer. It established the initial communication and contact points as well as provides the initial documentation in electronic media for the customer. Contact the SDTS Manager (SM) for the names of numbers of the current contact points.

Novel Transparent Urinary Tract Simulator Improves Teaching of Urological Operation Skills at a Single Institution.

PubMed

Zhong, Xiao; Wang, Pingxian; Feng, Jiayu; Hu, Wengang; Huang, Chibing

2015-01-01

This randomized controlled study compared a novel transparent urinary tract simulator with the traditional opaque urinary tract simulator as an aid for efficiently teaching urological surgical procedures. Senior medical students were tested on their understanding of urological theory before and after lectures concerning urinary system disease. The students received operative training using the transparent urinary tract simulator (experimental group, n = 80) or the J3311 opaque plastic urinary tract simulator (control, n = 80), specifically in catheterization and retrograde double-J stent implantation. The operative training was followed by a skills test and student satisfaction survey. The test scores for theory were similar between the two groups, before and after training. Students in the experimental group performed significantly better than those in the control group on the procedural skills test, and also had significantly better self-directed learning skills, analytical skills, and greater motivation to learn. During the initial step of training, the novel transparent urinary tract simulator significantly improved the efficiency of teaching urological procedural skills compared with the traditional opaque device. © 2015 S. Karger AG, Basel.

Hot Spot Initiation Patterns in Shocked Explosives and Propellants Recorded by Thermal Film.

DTIC Science & Technology

1980-12-02

8 PropellantsVRA-23andALTU-16 . . . . . ........ .. 9 PBXN - 106 Simulant . . . . . .. . . . . . . . . . . . . . 9 CONCLUSIONS...Enlargement (120X) Showing Crater Pattern With Charred Rim Produced By Fracture of Glass Beads in PBXN - 106 Simulant . . . . . 21 12 Model of Crater...explosives and high energy propellants as well as with an explo- sive ( PBXN - 106 ) simulant. The results of these tests are reported below. PRESSED TNT. Figure

Flight test of a propulsion controlled aircraft system on the NASA F-15 airplane

NASA Technical Reports Server (NTRS)

Burcham, Frank W., Jr.; Maine, Trindel A.

1995-01-01

Flight tests of the propulsion controlled aircraft (PCA) system on the NASA F-15 airplane evolved as a result of a long series of simulation and flight tests. Initially, the simulation results were very optimistic. Early flight tests showed that manual throttles-only control was much more difficult than the simulation, and a flight investigation was flown to acquire data to resolve this discrepancy. The PCA system designed and developed by MDA evolved as these discrepancies were found and resolved, requiring redesign of the PCA software and modification of the flight test plan. Small throttle step inputs were flown to provide data for analysis, simulation update, and control logic modification. The PCA flight tests quickly revealed less than desired performance, but the extensive flexibility built into the flight PCA software allowed rapid evaluation of alternate gains, filters, and control logic, and within 2 weeks, the PCA system was functioning well. The initial objective of achieving adequate control for up-and-away flying and approaches was satisfied, and the option to continue to actual landings was achieved. After the PCA landings were accomplished, other PCA features were added, and additional maneuvers beyond those originally planned were flown. The PCA system was used to recover from extreme upset conditions, descend, and make approaches to landing. A heading mode was added, and a single engine plus rudder PCA mode was also added and flown. The PCA flight envelope was expanded far beyond that originally designed for. Guest pilots from the USAF, USN, NASA, and the contractor also flew the PCA system and were favorably impressed.

Should tsunami simulations include a nonzero initial horizontal velocity?

NASA Astrophysics Data System (ADS)

Lotto, Gabriel C.; Nava, Gabriel; Dunham, Eric M.

2017-08-01

Tsunami propagation in the open ocean is most commonly modeled by solving the shallow water wave equations. These equations require initial conditions on sea surface height and depth-averaged horizontal particle velocity or, equivalently, horizontal momentum. While most modelers assume that initial velocity is zero, Y.T. Song and collaborators have argued for nonzero initial velocity, claiming that horizontal displacement of a sloping seafloor imparts significant horizontal momentum to the ocean. They show examples in which this effect increases the resulting tsunami height by a factor of two or more relative to models in which initial velocity is zero. We test this claim with a "full-physics" integrated dynamic rupture and tsunami model that couples the elastic response of the Earth to the linearized acoustic-gravitational response of a compressible ocean with gravity; the model self-consistently accounts for seismic waves in the solid Earth, acoustic waves in the ocean, and tsunamis (with dispersion at short wavelengths). Full-physics simulations of subduction zone megathrust ruptures and tsunamis in geometries with a sloping seafloor confirm that substantial horizontal momentum is imparted to the ocean. However, almost all of that initial momentum is carried away by ocean acoustic waves, with negligible momentum imparted to the tsunami. We also compare tsunami propagation in each simulation to that predicted by an equivalent shallow water wave simulation with varying assumptions regarding initial velocity. We find that the initial horizontal velocity conditions proposed by Song and collaborators consistently overestimate the tsunami amplitude and predict an inconsistent wave profile. Finally, we determine tsunami initial conditions that are rigorously consistent with our full-physics simulations by isolating the tsunami waves from ocean acoustic and seismic waves at some final time, and backpropagating the tsunami waves to their initial state by solving the adjoint problem. The resulting initial conditions have negligible horizontal velocity.[Figure not available: see fulltext.

Three Dimensional Constraint Effects on the Estimated (Delta)CTOD during the Numerical Simulation of Different Fatigue Threshold Testing Techniques

NASA Technical Reports Server (NTRS)

Seshadri, Banavara R.; Smith, Stephen W.

2007-01-01

Variation in constraint through the thickness of a specimen effects the cyclic crack-tip-opening displacement (DELTA CTOD). DELTA CTOD is a valuable measure of crack growth behavior, indicating closure development, constraint variations and load history effects. Fatigue loading with a continual load reduction was used to simulate the load history associated with fatigue crack growth threshold measurements. The constraint effect on the estimated DELTA CTOD is studied by carrying out three-dimensional elastic-plastic finite element simulations. The analysis involves numerical simulation of different standard fatigue threshold test schemes to determine how each test scheme affects DELTA CTOD. The American Society for Testing and Materials (ASTM) prescribes standard load reduction procedures for threshold testing using either the constant stress ratio (R) or constant maximum stress intensity (K(sub max)) methods. Different specimen types defined in the standard, namely the compact tension, C(T), and middle cracked tension, M(T), specimens were used in this simulation. The threshold simulations were conducted with different initial K(sub max) values to study its effect on estimated DELTA CTOD. During each simulation, the DELTA CTOD was estimated at every load increment during the load reduction procedure. Previous numerical simulation results indicate that the constant R load reduction method generates a plastic wake resulting in remote crack closure during unloading. Upon reloading, this remote contact location was observed to remain in contact well after the crack tip was fully open. The final region to open is located at the point at which the load reduction was initiated and at the free surface of the specimen. However, simulations carried out using the constant Kmax load reduction procedure did not indicate remote crack closure. Previous analysis results using various starting K(sub max) values and different load reduction rates have indicated DELTA CTOD is independent of specimen size. A study of the effect of specimen thickness and geometry on the measured DELTA CTOD for various load reduction procedures and its implication in the estimation of fatigue crack growth threshold values is discussed.

Application of Simulated Reactivity Feedback in Nonnuclear Testing of a Direct-Drive Gas-Cooled Reactor

NASA Technical Reports Server (NTRS)

Bragg-Sitton, S. M.; Webster, K. L.

2007-01-01

Nonnuclear testing can be a valuable tool in the development of an in-space nuclear power or propulsion system. In a nonnuclear test facility, electric heaters are used to simulate heat from nuclear fuel. Standard testing allows one to fully assess thermal, heat transfer, and stress related attributes of a given system but fails to demonstrate the dynamic response that would be present in an integrated, fueled reactor system. The integration of thermal hydraulic hardware tests with simulated neutronic response provides a bridge between electrically heated testing and full nuclear testing. By implementing a neutronic response model to simulate the dynamic response that would be expected in a fueled reactor system, one can better understand system integration issues, characterize integrated system response times and response and response characteristics, and assess potential design improvements with a relatively small fiscal investment. Initial system dynamic response testing was demonstrated on the integrated SAFE 100a heat pipe cooled, electrically heated reactor and heat exchanger hardware. This Technical Memorandum discusses the status of the planned dynamic test methodology for implementation in the direct-drive gas-cooled reactor testing and assesses the additional instrumentation needed to implement high-fidelity dynamic testing.

Cell module and fuel conditioner

NASA Technical Reports Server (NTRS)

Hoover, D. Q., Jr.

1980-01-01

Measurements of stack height changes with temperature and cell material characteristics were made. Stack 559 was assembled and components were fabricated for 560, 561, and 562. Stack 425 was transferred from the parallel DOE program and installed in the OS/IES simulation loop for mechanical and electrical testing. Construction and preliminary checkout of the 2 kW test facility was completed and design and procurement of the 8 kW test facility was initiated. The fuel conditioning subsystem design continued to evolve and the state points for the current design were calculated at full and part load conditions. Steam reforming catalyst activity tests were essentially completed and aging tests and CO shift converter tests were initiated.

Particle acceleration in solar active regions being in the state of self-organized criticality.

NASA Astrophysics Data System (ADS)

Vlahos, Loukas

We review the recent observational results on flare initiation and particle acceleration in solar active regions. Elaborating a statistical approach to describe the spatiotemporally intermittent electric field structures formed inside a flaring solar active region, we investigate the efficiency of such structures in accelerating charged particles (electrons and protons). The large-scale magnetic configuration in the solar atmosphere responds to the strong turbulent flows that convey perturbations across the active region by initiating avalanche-type processes. The resulting unstable structures correspond to small-scale dissipation regions hosting strong electric fields. Previous research on particle acceleration in strongly turbulent plasmas provides a general framework for addressing such a problem. This framework combines various electromagnetic field configurations obtained by magnetohydrodynamical (MHD) or cellular automata (CA) simulations, or by employing a statistical description of the field’s strength and configuration with test particle simulations. We work on data-driven 3D magnetic field extrapolations, based on a self-organized criticality models (SOC). A relativistic test-particle simulation traces each particle’s guiding center within these configurations. Using the simulated particle-energy distributions we test our results against observations, in the framework of the collisional thick target model (CTTM) of solar hard X-ray (HXR) emission and compare our results with the current observations.

The NASA Lewis integrated propulsion and flight control simulator

NASA Technical Reports Server (NTRS)

Bright, Michelle M.; Simon, Donald L.

1991-01-01

A new flight simulation facility was developed at NASA-Lewis. The purpose of this flight simulator is to allow integrated propulsion control and flight control algorithm development and evaluation in real time. As a preliminary check of the simulator facility capabilities and correct integration of its components, the control design and physics models for a short take-off and vertical landing fighter aircraft model were shown, with their associated system integration and architecture, pilot vehicle interfaces, and display symbology. The initial testing and evaluation results show that this fixed based flight simulator can provide real time feedback and display of both airframe and propulsion variables for validation of integrated flight and propulsion control systems. Additionally, through the use of this flight simulator, various control design methodologies and cockpit mechanizations can be tested and evaluated in a real time environment.

Accuracy of MHD simulations: Effects of simulation initialization in GUMICS-4

NASA Astrophysics Data System (ADS)

Lakka, Antti; Pulkkinen, Tuija; Dimmock, Andrew; Osmane, Adnane; Palmroth, Minna; Honkonen, Ilja

2016-04-01

We conducted a study aimed at revealing how different global magnetohydrodynamic (MHD) simulation initialization methods affect the dynamics in different parts of the Earth's magnetosphere-ionosphere system. While such magnetosphere-ionosphere coupling codes have been used for more than two decades, their testing still requires significant work to identify the optimal numerical representation of the physical processes. We used the Grand Unified Magnetosphere-Ionosphere Coupling Simulation (GUMICS-4), the only European global MHD simulation being developed by the Finnish Meteorological Institute. GUMICS-4 was put to a test that included two stages: 1) a 10 day Omni data interval was simulated and the results were validated by comparing both the bow shock and the magnetopause spatial positions predicted by the simulation to actual measurements and 2) the validated 10 day simulation run was used as a reference in a comparison of five 3 + 12 hour (3 hour synthetic initialisation + 12 hour actual simulation) simulation runs. The 12 hour input was not only identical in each simulation case but it also represented a subset of the 10 day input thus enabling quantifying the effects of different synthetic initialisations on the magnetosphere-ionosphere system. The used synthetic initialisation data sets were created using stepwise, linear and sinusoidal functions. Switching the used input from the synthetic to real Omni data was immediate. The results show that the magnetosphere forms in each case within an hour after the switch to real data. However, local dissimilarities are found in the magnetospheric dynamics after formation depending on the used initialisation method. This is evident especially in the inner parts of the lobe.

Assessment of statistical education in Indonesia: Preliminary results and initiation to simulation-based inference

NASA Astrophysics Data System (ADS)

Saputra, K. V. I.; Cahyadi, L.; Sembiring, U. A.

2018-01-01

Start in this paper, we assess our traditional elementary statistics education and also we introduce elementary statistics with simulation-based inference. To assess our statistical class, we adapt the well-known CAOS (Comprehensive Assessment of Outcomes in Statistics) test that serves as an external measure to assess the student’s basic statistical literacy. This test generally represents as an accepted measure of statistical literacy. We also introduce a new teaching method on elementary statistics class. Different from the traditional elementary statistics course, we will introduce a simulation-based inference method to conduct hypothesis testing. From the literature, it has shown that this new teaching method works very well in increasing student’s understanding of statistics.

On random field Completely Automated Public Turing Test to Tell Computers and Humans Apart generation.

PubMed

Kouritzin, Michael A; Newton, Fraser; Wu, Biao

2013-04-01

Herein, we propose generating CAPTCHAs through random field simulation and give a novel, effective and efficient algorithm to do so. Indeed, we demonstrate that sufficient information about word tests for easy human recognition is contained in the site marginal probabilities and the site-to-nearby-site covariances and that these quantities can be embedded directly into certain conditional probabilities, designed for effective simulation. The CAPTCHAs are then partial random realizations of the random CAPTCHA word. We start with an initial random field (e.g., randomly scattered letter pieces) and use Gibbs resampling to re-simulate portions of the field repeatedly using these conditional probabilities until the word becomes human-readable. The residual randomness from the initial random field together with the random implementation of the CAPTCHA word provide significant resistance to attack. This results in a CAPTCHA, which is unrecognizable to modern optical character recognition but is recognized about 95% of the time in a human readability study.

Ignition-and-Growth Modeling of NASA Standard Detonator and a Linear Shaped Charge

NASA Technical Reports Server (NTRS)

Oguz, Sirri

2010-01-01

The main objective of this study is to quantitatively investigate the ignition and shock sensitivity of NASA Standard Detonator (NSD) and the shock wave propagation of a linear shaped charge (LSC) after being shocked by NSD flyer plate. This combined explosive train was modeled as a coupled Arbitrary Lagrangian-Eulerian (ALE) model with LS-DYNA hydro code. An ignition-and-growth (I&G) reactive model based on unreacted and reacted Jones-Wilkins-Lee (JWL) equations of state was used to simulate the shock initiation. Various NSD-to-LSC stand-off distances were analyzed to calculate the shock initiation (or failure to initiate) and detonation wave propagation along the shaped charge. Simulation results were verified by experimental data which included VISAR tests for NSD flyer plate velocity measurement and an aluminum target severance test for LSC performance verification. Parameters used for the analysis were obtained from various published data or by using CHEETAH thermo-chemical code.

Stream-water storage in the ocean using an impermeable membrane

NASA Astrophysics Data System (ADS)

Murabayashi, E. T.; Asuka, M.; Yamada, R.; Fok, Y. S.; Gee, H. K.

1983-05-01

The conceptual feasibility of storing fresh water in the ocean was investigated using a plastic membrane as the reservoir liner. In the initial phase, two physical hydraulic models were constructed to test the concept. The first was a water-filled, glass-sided box to observe the movement and reaction of the membrane to various simulated effects of currents, waves, and sediment deposition. The second was a 1:400-scale model (6.7 x 6.1 m) of West Loch, Pearl Harbor (a potential field application site), with 1:24 vertical exaggeration for similitude. The curtain method was used because it can enclose a large water body. The effect of wind, waves, tides, and currents on the curtain were simulated and the reactions observed. Although modeling is a useful tool for investigating initial concepts, its direct field application is limited because of scaling. Curtains, floating reservoirs, and bags were constructed of polyethylene sheets and deployed. All worked well after modifications were made following initial testing.

Development of the CELSS Emulator at NASA JSC

NASA Technical Reports Server (NTRS)

Cullingford, Hatice S.

1989-01-01

The Controlled Ecological Life Support System (CELSS) Emulator is under development at the NASA Johnson Space Center (JSC) with the purpose to investigate computer simulations of integrated CELSS operations involving humans, plants, and process machinery. This paper describes Version 1.0 of the CELSS Emulator that was initiated in 1988 on the JSC Multi Purpose Applications Console Test Bed as the simulation framework. The run module of the simulation system now contains a CELSS model called BLSS. The CELSS Emulator makes it possible to generate model data sets, store libraries of results for further analysis, and also display plots of model variables as a function of time. The progress of the project is presented with sample test runs and simulation display pages.

Scale refinement and initial evaluation of a behavioral health function measurement tool for work disability evaluation.

PubMed

Marfeo, Elizabeth E; Ni, Pengsheng; Haley, Stephen M; Bogusz, Kara; Meterko, Mark; McDonough, Christine M; Chan, Leighton; Rasch, Elizabeth K; Brandt, Diane E; Jette, Alan M

2013-09-01

To use item response theory (IRT) data simulations to construct and perform initial psychometric testing of a newly developed instrument, the Social Security Administration Behavioral Health Function (SSA-BH) instrument, that aims to assess behavioral health functioning relevant to the context of work. Cross-sectional survey followed by IRT calibration data simulations. Community. Sample of individuals applying for Social Security Administration disability benefits: claimants (n=1015) and a normative comparative sample of U.S. adults (n=1000). None. SSA-BH measurement instrument. IRT analyses supported the unidimensionality of 4 SSA-BH scales: mood and emotions (35 items), self-efficacy (23 items), social interactions (6 items), and behavioral control (15 items). All SSA-BH scales demonstrated strong psychometric properties including reliability, accuracy, and breadth of coverage. High correlations of the simulated 5- or 10-item computer adaptive tests with the full item bank indicated robust ability of the computer adaptive testing approach to comprehensively characterize behavioral health function along 4 distinct dimensions. Initial testing and evaluation of the SSA-BH instrument demonstrated good accuracy, reliability, and content coverage along all 4 scales. Behavioral function profiles of Social Security Administration claimants were generated and compared with age- and sex-matched norms along 4 scales: mood and emotions, behavioral control, social interactions, and self-efficacy. Using the computer adaptive test-based approach offers the ability to collect standardized, comprehensive functional information about claimants in an efficient way, which may prove useful in the context of the Social Security Administration's work disability programs. Copyright © 2013 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Extraction-Separation Performance and Dynamic Modeling of Orion Test Vehicles with Adams Simulation: 3rd Edition

NASA Technical Reports Server (NTRS)

Varela, Jose G.; Reddy, Satish; Moeller, Enrique; Anderson, Keith

2017-01-01

NASA's Orion Capsule Parachute Assembly System (CPAS) Project is now in the qualification phase of testing, and the Adams simulation has continued to evolve to model the complex dynamics experienced during the test article extraction and separation phases of flight. The ability to initiate tests near the upper altitude limit of the Orion parachute deployment envelope requires extractions from the aircraft at 35,000 ft-MSL. Engineering development phase testing of the Parachute Test Vehicle (PTV) carried by the Carriage Platform Separation System (CPSS) at altitude resulted in test support equipment hardware failures due to increased energy caused by higher true airspeeds. As a result, hardware modifications became a necessity requiring ground static testing of the textile components to be conducted and a new ground dynamic test of the extraction system to be devised. Force-displacement curves from static tests were incorporated into the Adams simulations, allowing prediction of loads, velocities and margins encountered during both flight and ground dynamic tests. The Adams simulation was then further refined by fine tuning the damping terms to match the peak loads recorded in the ground dynamic tests. The failure observed in flight testing was successfully replicated in ground testing and true safety margins of the textile components were revealed. A multi-loop energy modulator was then incorporated into the system level Adams simulation model and the effect on improving test margins be properly evaluated leading to high confidence ground verification testing of the final design solution.

Initial testing of a variable-stroke Stirling engine

NASA Technical Reports Server (NTRS)

Thieme, L. G.

1985-01-01

In support of the U.S. Department of Energy's Stirling Engine Highway Vehicle Systems Program, NASA Lewis Research Center is evaluating variable-stroke control for Stirling engines. The engine being tested is the Advenco Stirling engine; this engine was manufactured by Philips Research Laboratories of the Netherlands and uses a variable-angle swash-plate drive to achieve variable stroke operation. The engine is described, initial steady-state test data taken at Lewis are presented, a major drive system failure and subsequent modifications are described. Computer simulation results are presented to show potential part-load efficiency gains with variable-stroke control.

Simulating video-assisted thoracoscopic lobectomy: a virtual reality cognitive task simulation.

PubMed

Solomon, Brian; Bizekis, Costas; Dellis, Sophia L; Donington, Jessica S; Oliker, Aaron; Balsam, Leora B; Zervos, Michael; Galloway, Aubrey C; Pass, Harvey; Grossi, Eugene A

2011-01-01

Current video-assisted thoracoscopic surgery training models rely on animals or mannequins to teach procedural skills. These approaches lack inherent teaching/testing capability and are limited by cost, anatomic variations, and single use. In response, we hypothesized that video-assisted thoracoscopic surgery right upper lobe resection could be simulated in a virtual reality environment with commercial software. An anatomy explorer (Maya [Autodesk Inc, San Rafael, Calif] models of the chest and hilar structures) and simulation engine were adapted. Design goals included freedom of port placement, incorporation of well-known anatomic variants, teaching and testing modes, haptic feedback for the dissection, ability to perform the anatomic divisions, and a portable platform. Preexisting commercial models did not provide sufficient surgical detail, and extensive modeling modifications were required. Video-assisted thoracoscopic surgery right upper lobe resection simulation is initiated with a random vein and artery variation. The trainee proceeds in a teaching or testing mode. A knowledge database currently includes 13 anatomic identifications and 20 high-yield lung cancer learning points. The "patient" is presented in the left lateral decubitus position. After initial camera port placement, the endoscopic view is displayed and the thoracoscope is manipulated via the haptic device. The thoracoscope port can be relocated; additional ports are placed using an external "operating room" view. Unrestricted endoscopic exploration of the thorax is allowed. An endo-dissector tool allows for hilar dissection, and a virtual stapling device divides structures. The trainee's performance is reported. A virtual reality cognitive task simulation can overcome the deficiencies of existing training models. Performance scoring is being validated as we assess this simulator for cognitive and technical surgical education. Copyright © 2011. Published by Mosby, Inc.

Parabolic Flights with Single-Engine Aerobatic Aircraft: Flight Profile and a Computer Simulator for its Optimization

NASA Astrophysics Data System (ADS)

Brigos, Miguel; Perez-Poch, Antoni; Alpiste, Francesc; Torner, Jordi; González Alonso, Daniel Ventura

2014-11-01

We report the results of residual acceleration obtained from initial tests of parabolic flights (more than 100 hours) performed with a small single-engine aerobatic aircraft (CAP10B), and propose a method that improves these figures. Such aircraft have proved capable of providing researchers with periods of up to 8 seconds of reduced gravity in the cockpit, with a gravity quality in the range of 0.1 g 0, where g 0 is the gravitational acceleration of the Earth. Such parabolas may be of interest to experimenters in the reduced gravity field, when this range of reduced gravity is acceptable for the experiment undertaken. They have also proven to be useful for motivational and educational campaigns. Furthermore, these flights may be of interest to researchers as a test-bed for obtaining a proof-of-concept for subsequent access to parabolic flights with larger aircraft or other microgravity platforms. The limited cost of the operations with these small aircraft allows us to perform them as part of a non-commercial joint venture between the Universitat Politècnica de Catalunya - BarcelonaTech (UPC), the Barcelona cluster BAIE and the Aeroclub Barcelona-Sabadell. Any improvements in the length and quality of reduced gravity would increase the capabilities of these small aircraft. To that end, we have developed a method based on a simulator for training aerobatic pilots. The simulation is performed with the CAD software for mechanical design Solidworks Motion{circledR }, which is widely distributed in industry and in universities. It specifically simulates the parabolic flight manoeuvre for our small aircraft and enables us to improve different aspects of the manoeuvre. The simulator is first validated with experimental data from the test flights. We have conducted an initial intensive period of specific pilot training with the aid of the simulator output. After such initial simulation-aided training, results show that the reduced gravity quality has significantly improved from 0.1 g 0 to 0.05 g 0. We conclude that single-engine aerobatic aircraft are capable of conducting small hypogravity experiments with the limitations described in the paper.

Fast two-position initial alignment for SINS using velocity plus angular rate measurements

NASA Astrophysics Data System (ADS)

Chang, Guobin

2015-10-01

An improved two-position initial alignment model for strapdown inertial navigation system is proposed. In addition to the velocity, angular rates are incorporated as measurements. The measurement equations in full three channels are derived in both navigation and body frames and the latter of which is found to be preferred. The cross-correlation between the process and the measurement noises is analyzed and addressed in the Kalman filter. The incorporation of the angular rates, without introducing additional device or external signal, speeds up the convergence of estimating the attitudes, especially the heading. In the simulation study, different algorithms are tested with different initial errors, and the advantages of the proposed method compared to the conventional one are validated by the simulation results.

Potential, velocity, and density fields from sparse and noisy redshift-distance samples - Method

NASA Technical Reports Server (NTRS)

Dekel, Avishai; Bertschinger, Edmund; Faber, Sandra M.

1990-01-01

A method for recovering the three-dimensional potential, velocity, and density fields from large-scale redshift-distance samples is described. Galaxies are taken as tracers of the velocity field, not of the mass. The density field and the initial conditions are calculated using an iterative procedure that applies the no-vorticity assumption at an initial time and uses the Zel'dovich approximation to relate initial and final positions of particles on a grid. The method is tested using a cosmological N-body simulation 'observed' at the positions of real galaxies in a redshift-distance sample, taking into account their distance measurement errors. Malmquist bias and other systematic and statistical errors are extensively explored using both analytical techniques and Monte Carlo simulations.

Modeling and simulation for space medicine operations: preliminary requirements considered

NASA Technical Reports Server (NTRS)

Dawson, D. L.; Billica, R. D.; McDonald, P. V.

2001-01-01

The NASA Space Medicine program is now developing plans for more extensive use of high-fidelity medical simulation systems. The use of simulation is seen as means to more effectively use the limited time available for astronaut medical training. Training systems should be adaptable for use in a variety of training environments, including classrooms or laboratories, space vehicle mockups, analog environments, and in microgravity. Modeling and simulation can also provide the space medicine development program a mechanism for evaluation of other medical technologies under operationally realistic conditions. Systems and procedures need preflight verification with ground-based testing. Traditionally, component testing has been accomplished, but practical means for "human in the loop" verification of patient care systems have been lacking. Medical modeling and simulation technology offer potential means to accomplish such validation work. Initial considerations in the development of functional requirements and design standards for simulation systems for space medicine are discussed.

Requirements for Modeling and Simulation for Space Medicine Operations: Preliminary Considerations

NASA Technical Reports Server (NTRS)

Dawson, David L.; Billica, Roger D.; Logan, James; McDonald, P. Vernon

2001-01-01

The NASA Space Medicine program is now developing plans for more extensive use of high-fidelity medical Simulation systems. The use of simulation is seen as means to more effectively use the limited time available for astronaut medical training. Training systems should be adaptable for use in a variety of training environments, including classrooms or laboratories, space vehicle mockups, analog environments, and in microgravity. Modeling and simulation can also provide the space medicine development program a mechanism for evaluation of other medical technologies under operationally realistic conditions. Systems and procedures need preflight verification with ground-based testing. Traditionally, component testing has been accomplished, but practical means for "human in the loop" verification of patient care systems have been lacking. Medical modeling and simulation technology offer potential means to accomplish such validation work. Initial considerations in the development of functional requirements and design standards for simulation systems for space medicine are discussed.

Evaluation of dispersion strengthened nickel-base alloy heat shields for space shuttle application

NASA Technical Reports Server (NTRS)

Johnson, R., Jr.; Killpatrick, D. H.

1976-01-01

The results obtained in a program to evaluate dispersion-strengthened nickel-base alloys for use in a metallic radiative thermal protection system operating at surface temperatures to 1477 K for the space shuttle were presented. Vehicle environments having critical effects on the thermal protection system are defined; TD Ni-20Cr characteristics of material used in the current study are compared with previous results; cyclic load, temperature, and pressure effects on sheet material residual strength are investigated; the effects of braze reinforcement in improving the efficiency of spotwelded joints are evaluated; parametric studies of metallic radiative thermal protection systems are reported; and the design, instrumentation, and testing of full scale subsize heat shield panels in two configurations are described. Initial tests of full scale subsize panels included simulated meteoroid impact tests, simulated entry flight aerodynamic heating, programmed differential pressure loads and temperatures simulating mission conditions, and acoustic tests simulating sound levels experienced during boost flight.

Measuring the Process and Quality of Informed Consent for Clinical Research: Development and Testing

PubMed Central

Cohn, Elizabeth Gross; Jia, Haomiao; Smith, Winifred Chapman; Erwin, Katherine; Larson, Elaine L.

2013-01-01

Purpose/Objectives To develop and assess the reliability and validity of an observational instrument, the Process and Quality of Informed Consent (P-QIC). Design A pilot study of the psychometrics of a tool designed to measure the quality and process of the informed consent encounter in clinical research. The study used professionally filmed, simulated consent encounters designed to vary in process and quality. Setting A major urban teaching hospital in the northeastern region of the United States. Sample 63 students enrolled in health-related programs participated in psychometric testing, 16 students participated in test-retest reliability, and 5 investigator-participant dyads were observed for the actual consent encounters. Methods For reliability and validity testing, students watched and rated videotaped simulations of four consent encounters intentionally varied in process and content and rated them with the proposed instrument. Test-retest reliability was established by raters watching the videotaped simulations twice. Inter-rater reliability was demonstrated by two simultaneous but independent raters observing an actual consent encounter. Main Research Variables The essential elements of information and communication for informed consent. Findings The initial testing of the P-QIC demonstrated reliable and valid psychometric properties in both the simulated standardized consent encounters and actual consent encounters in the hospital setting. Conclusions The P-QIC is an easy-to-use observational tool that provides a quick assessment of the areas of strength and areas that need improvement in a consent encounter. It can be used in the initial trainings of new investigators or consent administrators and in ongoing programs of improvement for informed consent. Implications for Nursing The development of a validated observational instrument will allow investigators to assess the consent process more accurately and evaluate strategies designed to improve it. PMID:21708532

Intraindividual variability in basic reaction time predicts middle-aged and older pilots' flight simulator performance.

PubMed

Kennedy, Quinn; Taylor, Joy; Heraldez, Daniel; Noda, Art; Lazzeroni, Laura C; Yesavage, Jerome

2013-07-01

Intraindividual variability (IIV) is negatively associated with cognitive test performance and is positively associated with age and some neurological disorders. We aimed to extend these findings to a real-world task, flight simulator performance. We hypothesized that IIV predicts poorer initial flight performance and increased rate of decline in performance among middle-aged and older pilots. Two-hundred and thirty-six pilots (40-69 years) completed annual assessments comprising a cognitive battery and two 75-min simulated flights in a flight simulator. Basic and complex IIV composite variables were created from measures of basic reaction time and shifting and divided attention tasks. Flight simulator performance was characterized by an overall summary score and scores on communication, emergencies, approach, and traffic avoidance components. Although basic IIV did not predict rate of decline in flight performance, it had a negative association with initial performance for most flight measures. After taking into account processing speed, basic IIV explained an additional 8%-12% of the negative age effect on initial flight performance. IIV plays an important role in real-world tasks and is another aspect of cognition that underlies age-related differences in cognitive performance.

Intraindividual Variability in Basic Reaction Time Predicts Middle-Aged and Older Pilots’ Flight Simulator Performance

PubMed Central

2013-01-01

Objectives. Intraindividual variability (IIV) is negatively associated with cognitive test performance and is positively associated with age and some neurological disorders. We aimed to extend these findings to a real-world task, flight simulator performance. We hypothesized that IIV predicts poorer initial flight performance and increased rate of decline in performance among middle-aged and older pilots. Method. Two-hundred and thirty-six pilots (40–69 years) completed annual assessments comprising a cognitive battery and two 75-min simulated flights in a flight simulator. Basic and complex IIV composite variables were created from measures of basic reaction time and shifting and divided attention tasks. Flight simulator performance was characterized by an overall summary score and scores on communication, emergencies, approach, and traffic avoidance components. Results. Although basic IIV did not predict rate of decline in flight performance, it had a negative association with initial performance for most flight measures. After taking into account processing speed, basic IIV explained an additional 8%–12% of the negative age effect on initial flight performance. Discussion. IIV plays an important role in real-world tasks and is another aspect of cognition that underlies age-related differences in cognitive performance. PMID:23052365

The Effect of Surface Patterning on Corrosion Resistance of Biomedical Devices

NASA Astrophysics Data System (ADS)

Guo, Mengnan; Toloei, Alisina; Rotermund, Harm H.

2016-10-01

In this study, two styles of surface topographies have been created on stainless steel wires to test their corrosion resistance as simulated implanted biomedical devices. Grade 316 LVM stainless steel wire was initially polished to G1500 surface finish before treatment to produce the two different topographies: 1. Unidirectional roughness was created using SiC papers and 2. Various patterns were created with specific hole diameter and inter-hole spacing using focused ion beam (FIB). In order to simulate the environment of implanted biomedical devices, a three-electrode electrochemical cell with 0.9% (by mass) NaCl solution has been used to test the corrosion resistance of the samples by potentiodynamic polarization test method. SEM and EDS analyzed the appearance and chemical composition of different elements including oxygen on the surface. The potential of stable pitting, time related to the initiation of the stable pitting, and the highest corrosion current associated with stable pitting have been compared for samples with the two styles of topography. It was found that surfaces with patterns have a relatively higher pitting potential and it takes longer time to initiate stable pitting than the surface without any patterns.

Alignment and Initial Operation of an Advanced Solar Simulator

NASA Technical Reports Server (NTRS)

Jaworske, Donald A.; Jefferies, Kent S.; Mason, Lee S.

1996-01-01

A solar simulator utilizing nine 30-kW xenon arc lamps was built to provide radiant power for testing a solar dynamic space power system in a thermal vacuum environment. The advanced solar simulator achieved the following values specific to the solar dynamic system: (1) a subtense angle of 1 deg; (2) the ability to vary solar simulator intensity up to 1.7 kW/sq m; (3) a beam diameter of 4.8 m; and (4) uniformity of illumination on the order of +/-10%. The flexibility of the solar simulator design allows for other potential uses of the facility.

A validated non-linear Kelvin-Helmholtz benchmark for numerical hydrodynamics

NASA Astrophysics Data System (ADS)

Lecoanet, D.; McCourt, M.; Quataert, E.; Burns, K. J.; Vasil, G. M.; Oishi, J. S.; Brown, B. P.; Stone, J. M.; O'Leary, R. M.

2016-02-01

The non-linear evolution of the Kelvin-Helmholtz instability is a popular test for code verification. To date, most Kelvin-Helmholtz problems discussed in the literature are ill-posed: they do not converge to any single solution with increasing resolution. This precludes comparisons among different codes and severely limits the utility of the Kelvin-Helmholtz instability as a test problem. The lack of a reference solution has led various authors to assert the accuracy of their simulations based on ad hoc proxies, e.g. the existence of small-scale structures. This paper proposes well-posed two-dimensional Kelvin-Helmholtz problems with smooth initial conditions and explicit diffusion. We show that in many cases numerical errors/noise can seed spurious small-scale structure in Kelvin-Helmholtz problems. We demonstrate convergence to a reference solution using both ATHENA, a Godunov code, and DEDALUS, a pseudo-spectral code. Problems with constant initial density throughout the domain are relatively straightforward for both codes. However, problems with an initial density jump (which are the norm in astrophysical systems) exhibit rich behaviour and are more computationally challenging. In the latter case, ATHENA simulations are prone to an instability of the inner rolled-up vortex; this instability is seeded by grid-scale errors introduced by the algorithm, and disappears as resolution increases. Both ATHENA and DEDALUS exhibit late-time chaos. Inviscid simulations are riddled with extremely vigorous secondary instabilities which induce more mixing than simulations with explicit diffusion. Our results highlight the importance of running well-posed test problems with demonstrated convergence to a reference solution. To facilitate future comparisons, we include as supplementary material the resolved, converged solutions to the Kelvin-Helmholtz problems in this paper in machine-readable form.

Numerical sedimentation particle-size analysis using the Discrete Element Method

NASA Astrophysics Data System (ADS)

Bravo, R.; Pérez-Aparicio, J. L.; Gómez-Hernández, J. J.

2015-12-01

Sedimentation tests are widely used to determine the particle size distribution of a granular sample. In this work, the Discrete Element Method interacts with the simulation of flow using the well known one-way-coupling method, a computationally affordable approach for the time-consuming numerical simulation of the hydrometer, buoyancy and pipette sedimentation tests. These tests are used in the laboratory to determine the particle-size distribution of fine-grained aggregates. Five samples with different particle-size distributions are modeled by about six million rigid spheres projected on two-dimensions, with diameters ranging from 2.5 ×10-6 m to 70 ×10-6 m, forming a water suspension in a sedimentation cylinder. DEM simulates the particle's movement considering laminar flow interactions of buoyant, drag and lubrication forces. The simulation provides the temporal/spatial distributions of densities and concentrations of the suspension. The numerical simulations cannot replace the laboratory tests since they need the final granulometry as initial data, but, as the results show, these simulations can identify the strong and weak points of each method and eventually recommend useful variations and draw conclusions on their validity, aspects very difficult to achieve in the laboratory.

Evaluation Program for Secondary Spacecraft Cells: Initial Evaluation Tests of General Electric Company 6.0 Ampere Hour Nickel Cadmium Spacecraft Cells for the Dynamic Explorer Satellite Program

NASA Technical Reports Server (NTRS)

Harkness, J. D.

1980-01-01

Evaluation tests of 10 nickel cadmium cells are described. Although pressures were greater than what normally was exhibited by General Electric cells in the past, it is recommended that these cells be placed on life test simulating the predicted Dynamic Explorer flight profiles.

The NASA Langley building solar project and the supporting Lewis solar technology program

NASA Technical Reports Server (NTRS)

Ragsdale, R. G.; Namkoong, D.

1974-01-01

A solar energy technology program is described that includes solar collector testing in an indoor solar simulator facility and in an outdoor test facility, property measurements of solar panel coatings, and operation of a laboratory-scale solar model system test facility. Early results from simulator tests indicate that non-selective coatings behave more nearly in accord with predicted performance than do selective coatings. Initial experiments on the decay rate of thermally stratified hot water in a storage tank have been run. Results suggest that where high temperature water is required, excess solar energy collected by a building solar system should be stored overnight in the form of chilled water rather than hot water.

Seasonal thermal energy storage in aquifers: Mathematical modeling studies in 1979

NASA Technical Reports Server (NTRS)

Tsang, C. F.

1980-01-01

A numerical model of water and heat flow in geologic media was developed, verified, and tested. The hydraulic parameters (transmittivity and storativity) and the location of a linear hydrologic barrier were simulated and compared with results from field experiments involving two injection-storage-recovery cycles. For both cycles, the initial simulated and observed temperatures agree (55c).

Initial Simulations of RF Waves in Hot Plasmas Using the FullWave Code

NASA Astrophysics Data System (ADS)

Zhao, Liangji; Svidzinski, Vladimir; Spencer, Andrew; Kim, Jin-Soo

2017-10-01

FullWave is a simulation tool that models RF fields in hot inhomogeneous magnetized plasmas. The wave equations with linearized hot plasma dielectric response are solved in configuration space on adaptive cloud of computational points. The nonlocal hot plasma dielectric response is formulated by calculating the plasma conductivity kernel based on the solution of the linearized Vlasov equation in inhomogeneous magnetic field. In an rf field, the hot plasma dielectric response is limited to the distance of a few particles' Larmor radii, near the magnetic field line passing through the test point. The localization of the hot plasma dielectric response results in a sparse matrix of the problem thus significantly reduces the size of the problem and makes the simulations faster. We will present the initial results of modeling of rf waves using the Fullwave code, including calculation of nonlocal conductivity kernel in 2D Tokamak geometry; the interpolation of conductivity kernel from test points to adaptive cloud of computational points; and the results of self-consistent simulations of 2D rf fields using calculated hot plasma conductivity kernel in a tokamak plasma with reduced parameters. Work supported by the US DOE ``SBIR program.

Direct Coexistence Methods to Determine the Solubility of Salts in Water from Numerical Simulations. Test Case NaCl.

PubMed

Manzanilla-Granados, Héctor M; Saint-Martín, Humberto; Fuentes-Azcatl, Raúl; Alejandre, José

2015-07-02

The solubility of NaCl, an equilibrium between a saturated solution of ions and a solid with a crystalline structure, was obtained from molecular dynamics simulations using the SPC/E and TIP4P-Ew water models. Four initial setups on supersaturated systems were tested on sodium chloride (NaCl) solutions to determine the equilibrium conditions and computational performance: (1) an ionic solution confined between two crystal plates of periodic NaCl, (2) a solution with all the ions initially distributed randomly, (3) a nanocrystal immersed in pure water, and (4) a nanocrystal immersed in an ionic solution. In some cases, the equilibration of the system can take several microseconds. The results from this work showed that the solubility of NaCl was the same, within simulation error, for the four setups, and in agreement with previously reported values from simulations with the setup (1). The system of a nanocrystal immersed in supersaturated solution was found to equilibrate faster than others. In agreement with laser-Doppler droplet measurements, at equilibrium with the solution the crystals in all the setups had a slight positive charge.

SP-100 initial startup and restart control strategy

NASA Astrophysics Data System (ADS)

Halfen, Frank J.; Wong, Kwok K.; Switick, Dennis M.; Shukla, Jaikaran N.

Startup control strategies for SP-100 are described. Revised control and operating strategies are discussed which have been developed and tested using the SP-100 dynamic simulation model Aries-GFS (Generic Flight System).

Effect of Abdominal Loading Location on Liver Motion: Experimental Assessment using Ultrafast Ultrasound Imaging and Simulation with a Human Body Model.

PubMed

Le Ruyet, Anicet; Berthet, Fabien; Rongiéras, Frédéric; Beillas, Philippe

2016-11-01

A protocol based on ultrafast ultrasound imaging was applied to study the in situ motion of the liver while the abdomen was subjected to compressive loading at 3 m/s by a hemispherical impactor or a seatbelt. The loading was applied to various locations between the lower abdomen and the mid thorax while feature points inside the liver were followed on the ultrasound movie (2000 frames per second). Based on tests performed on five post mortem human surrogates (including four tested in the current study), trends were found between the loading location and feature point trajectory parameters such as the initial angle of motion or the peak displacement in the direction of impact. The impactor tests were then simulated using the GHBMC M50 human body model that was globally scaled to the dimensions of each surrogate. Some of the experimental trends observed could be reproduced in the simulations (e.g. initial angle) while others differed more widely (e.g. final caudal motion). The causes for the discrepancies need to be further investigated. The liver strain energy density predicted by the model was also widely affected by the impact location. Experimental and simulation results both highlight the importance of the liver position with respect to the impactor when studying its response in situ.

Evaluation of Fracture Initiation in the Mannesmann Piercing Process

NASA Astrophysics Data System (ADS)

Fanini, S.; Ghiotti, A.; Bruschi, S.

2007-04-01

One of the challenging objectives in studying the Mannesmann piercing process is to predict the fracture initiation, known as "Mannesmann effect", in order to design and optimize the working parameters of the piercing process. The objective of the paper is to investigate the workability of a tube steel tested in the same conditions of the Mannesman piercing process. The stress and strain states as well as temperature fields arising during the process are identified through numerical simulations. The hot tensile test is chosen for fundamental studies on fracture initiation, as a tensile state of stress in the centre of the billet in the first stages of the piercing process before the plug arrival seems to be one of the main causes of the crack initiation. The material constants of energy-based models implemented in FEM codes are calculated and numerical results are compared with non-plug piercing tests carried out on the industrial plant.

System Engineering Strategy for Distributed Multi-Purpose Simulation Architectures

NASA Technical Reports Server (NTRS)

Bhula, Dlilpkumar; Kurt, Cindy Marie; Luty, Roger

2007-01-01

This paper describes the system engineering approach used to develop distributed multi-purpose simulations. The multi-purpose simulation architecture focuses on user needs, operations, flexibility, cost and maintenance. This approach was used to develop an International Space Station (ISS) simulator, which is called the International Space Station Integrated Simulation (ISIS)1. The ISIS runs unmodified ISS flight software, system models, and the astronaut command and control interface in an open system design that allows for rapid integration of multiple ISS models. The initial intent of ISIS was to provide a distributed system that allows access to ISS flight software and models for the creation, test, and validation of crew and ground controller procedures. This capability reduces the cost and scheduling issues associated with utilizing standalone simulators in fixed locations, and facilitates discovering unknowns and errors earlier in the development lifecycle. Since its inception, the flexible architecture of the ISIS has allowed its purpose to evolve to include ground operator system and display training, flight software modification testing, and as a realistic test bed for Exploration automation technology research and development.

[Evaluation of the impact and efficiency of high-fidelity simulation for neonatal resuscitation in midwifery education].

PubMed

Coyer, C; Gascoin, G; Sentilhes, L; Savagner, C; Berton, J; Beringue, F

2014-09-01

Prompt initiation of appropriate neonatal resuscitation skills is critical for the neonate experiencing difficulty transitioning to extra-uterine life. Expertise in neonatal resuscitation is essential for personnel involved in the care of newborns, above all for midwives who are sometimes alone to initiate the first resuscitation. The use of simulation training is considered to be an indispensable tool to address these challenges, not only in continuing education but also in midwifery education. The aim of this study was to evaluate the impact and efficiency of high-fidelity simulation for neonatal resuscitation in midwifery education. This was a prospective monocentric study conducted in the Angers university hospital between October and December 2012 and included two groups of midwifery students (n=40) who received high-fidelity simulation as part of their basic midwifery education. Participants' perceptions of the knowledge, skills, and confidence gained following training in high-fidelity simulation for neonatal resuscitation were determined using a pre-/post-test questionnaire design completed during the training and also several months after the course, as well as after the students had begun working. A satisfaction survey to evaluate this training was also completed at the same time. With a good participation rate (67.5%), the survey showed a high degree of satisfaction among the participants. This training was described as facilitating their hire in one third of cases. A significant increase in self-assessment of skills scores was observed between the pre-test and post-test (P<0.001), the pre-test and the distance test (P<0.001), and the post-test and distance test (P=0.007). Although a decrease in the median score was observed on the knowledge questionnaire given as a post-test, this median remained significantly higher than that obtained on the pre-test (P=0.03). The significant improvement in knowledge during the session and its preservation after a few months confirmed the efficacy of this teaching method. The simulation training increased the participants' perceptions of their knowledge, skills, and confidence in conducting neonatal resuscitation. These preliminary results are very encouraging and argue in favor of generalizing this teaching method. However, this training could be more profitable if it was proposed earlier in the midwifery curriculum and organized with a multidisciplinary team (pediatric and anesthesia residents). Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Testing Instrument for Flight-Simulator Displays

NASA Technical Reports Server (NTRS)

Haines, Richard F.

1987-01-01

Displays for flight-training simulators rapidly aligned with aid of integrated optical instrument. Calibrations and tests such as aligning boresight of display with respect to user's eyes, checking and adjusting display horizon, checking image sharpness, measuring illuminance of displayed scenes, and measuring distance of optical focus of scene performed with single unit. New instrument combines all measurement devices in single, compact, integrated unit. Requires just one initial setup. Employs laser and produces narrow, collimated beam for greater measurement accuracy. Uses only one moving part, double right prism, to position laser beam.

Pilot interaction with automated airborne decision making systems

NASA Technical Reports Server (NTRS)

Rouse, W. B.; Hammer, J. M.; Mitchell, C. M.; Morris, N. M.; Lewis, C. M.; Yoon, W. C.

1985-01-01

Progress was made in the three following areas. In the rule-based modeling area, two papers related to identification and significane testing of rule-based models were presented. In the area of operator aiding, research focused on aiding operators in novel failure situations; a discrete control modeling approach to aiding PLANT operators was developed; and a set of guidelines were developed for implementing automation. In the area of flight simulator hardware and software, the hardware will be completed within two months and initial simulation software will then be integrated and tested.

Verifying Safeguards Declarations with INDEPTH: A Sensitivity Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grogan, Brandon R; Richards, Scott

2017-01-01

A series of ORIGEN calculations were used to simulate the irradiation and decay of a number of spent fuel assemblies. These simulations focused on variations in the irradiation history that achieved the same terminal burnup through a different set of cycle histories. Simulated NDA measurements were generated for each test case from the ORIGEN data. These simulated measurement types included relative gammas, absolute gammas, absolute gammas plus neutrons, and concentrations of a set of six isotopes commonly measured by NDA. The INDEPTH code was used to reconstruct the initial enrichment, cooling time, and burnup for each irradiation using each simulatedmore » measurement type. The results were then compared to the initial ORIGEN inputs to quantify the size of the errors induced by the variations in cycle histories. Errors were compared based on the underlying changes to the cycle history, as well as the data types used for the reconstructions.« less

Development and application of dynamic simulations of a subsonic wind tunnel

NASA Technical Reports Server (NTRS)

Szuch, J. R.; Cole, G. L.; Seidel, R. C.; Arpasi, D. J.

1986-01-01

Efforts are currently underway at NASA Lewis to improve and expand ground test facilities and to develop supporting technologies to meet anticipated aeropropulsion research needs. Many of these efforts have been focused on a proposed rehabilitation of the Altitude Wind Tunnel (AWT). In order to insure a technically sound design, an AWT modeling program (both analytical and physical) was initiated to provide input to the AWT final design process. This paper describes the approach taken to develop analytical, dynamic computer simulations of the AWT, and the use of these simulations as test-beds for: (1) predicting the dynamic response characteristics of the AWT, and (2) evaluating proposed AWT control concepts. Plans for developing a portable, real-time simulator for the AWT facility are also described.

Geometry and Simulation Results for a Gas Turbine Representative of the Energy Efficient Engine (EEE)

NASA Technical Reports Server (NTRS)

Claus, Russell W.; Beach, Tim; Turner, Mark; Hendricks, Eric S.

2015-01-01

This paper describes the geometry and simulation results of a gas-turbine engine based on the original EEE engine developed in the 1980s. While the EEE engine was never in production, the technology developed during the program underpins many of the current generation of gas turbine engines. This geometry is being explored as a potential multi-stage turbomachinery test case that may be used to develop technology for virtual full-engine simulation. Simulation results were used to test the validity of each component geometry representation. Results are compared to a zero-dimensional engine model developed from experimental data. The geometry is captured in a series of Initial Graphical Exchange Specification (IGES) files and is available on a supplemental DVD to this report.

Pretest analysis document for Test S-FS-7

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hall, D.G.

This report documents the pretest calculations completed for Semiscale Test S-FS-7. This test will simulate a transient initiated by a 14.3% break in a steam generator bottom feedwater line downstream of the check valve. The initial conditions represent normal operating conditions for a C-E System 80 nuclear power plant. Predictions of transients resulting from feedwater line breaks in these plants have indicated that significant primary system overpressurization may occur. The results of a RELAP5/MOD2/CY21 code calculation indicate that the test objectives for Test S-FS-7 can be achieved. The primary system overpressurization will occur but pose no threat to personnel ormore » to plant integrity. 3 refs., 15 figs., 5 tabs.« less

Pretest analysis document for Test S-FS-11

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hall, D.G.; Shaw, R.A.

This report documents the pretest calculations completed for Semiscale Test S-FS-11. This test will simulate a transient initiated by a 50% break in a steam generator bottom feedwater line downstream of the check valve. The initial conditions represents normal operating conditions for a C-E System 80 nuclear plant. Prediction of transients resulting from feedwater line breaks in these plants have indicated that significant primary system overpressurization may occur. The results of a RELAP5/MOD2/CY21 code calculation indicate that the test objectives for Test S-FS-11 can be achieved. The primary system overpressurization will occur but pose no threat to personnel or plantmore » integrity. 3 refs., 15 figs., 5 tabs.« less

Initial Testing of the Stainless Steel NaK-Cooled Circuit (SNaKC)

NASA Technical Reports Server (NTRS)

Garber, Anne; Godfroy, Thomas

2007-01-01

An actively pumped alkali metal flow circuit, designed and fabricated at the NASA Marshall Space Flight Center, is currently undergoing testing in the Early Flight Fission Test Facility (EFF-TF). Sodium potassium (NaK) was selected as the primary coolant. Basic circuit components include: simulated reactor core, NaK to gas heat exchanger, electromagnetic liquid metal pump, liquid metal flowmeter, load/drain reservoir, expansion reservoir, test section, and instrumentation. Operation of the circuit is based around the 37-pin partial-array core (pin and flow path dimensions are the same as those in a full core), designed to operate at 33 kWt. This presentation addresses the construction, fill and initial testing of the Stainless Steel NaK-Cooled Circuit (SNaKC).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parkin, E. R.; Bicknell, G. V., E-mail: parkin@mso.anu.edu.au

Global three-dimensional magnetohydrodynamic (MHD) simulations of turbulent accretion disks are presented which start from fully equilibrium initial conditions in which the magnetic forces are accounted for and the induction equation is satisfied. The local linear theory of the magnetorotational instability (MRI) is used as a predictor of the growth of magnetic field perturbations in the global simulations. The linear growth estimates and global simulations diverge when nonlinear motions-perhaps triggered by the onset of turbulence-upset the velocity perturbations used to excite the MRI. The saturated state is found to be independent of the initially excited MRI mode, showing that once themore » disk has expelled the initially net flux field and settled into quasi-periodic oscillations in the toroidal magnetic flux, the dynamo cycle regulates the global saturation stress level. Furthermore, time-averaged measures of converged turbulence, such as the ratio of magnetic energies, are found to be in agreement with previous works. In particular, the globally averaged stress normalized to the gas pressure <{alpha}{sub P}>bar = 0.034, with notably higher values achieved for simulations with higher azimuthal resolution. Supplementary tests are performed using different numerical algorithms and resolutions. Convergence with resolution during the initial linear MRI growth phase is found for 23-35 cells per scale height (in the vertical direction).« less

Docking simulation analysis of range data requirements for the orbital maneuvering vehicle

NASA Technical Reports Server (NTRS)

Micheal, J. D.; Vinz, F. L.

1985-01-01

The results of an initial study are reported assess the controllability of the Orbital Maneuvering Vehicle (OMV) for terminal closure and docking are reported. The vehicle characteristics used in this study are those of the Marshall Space Flight Center (MSFC) baseline OMV which were published with the request for proposals for preliminary design of this vehicle. This simulation was conducted at MSFC using the Target Motion Simulator. The study focused on the OMV manual mode capability to accommodate both stabilized and tumbling target engagements with varying complements of range and range rate data displayed to the OMV operator. Four trained test subjects performed over 400 simulated orbital dockings during this study. A firm requirement for radar during the terminal closure and dock phase of the OMV mission was not established by these simulations. Fifteen pound thrusters recommended in the MSFC baseline design were found to be advantageous for initial rate matching maneuvers with unstabilized targets; however, lower thrust levels were desirable for making the final docking maneuvers.

Uniaxial low cycle fatigue behavior for pre-corroded 16MND5 bainitic steel in simulated pressurized water reactor environment

NASA Astrophysics Data System (ADS)

Chen, Xu; Ren, Bin; Yu, Dunji; Xu, Bin; Zhang, Zhe; Chen, Gang

2018-06-01

The effects of uniaxial tension properties and low cycle fatigue behavior of 16MND5 bainitic steel cylinder pre-corroded in simulated pressurized water reactor (PWR) were investigated by fatigue at room temperature in air and immersion test system, scanning electron microscopy (SEM), energy disperse spectroscopy (EDS). The experimental results indicated that the corrosion fatigue lives of 16MND5 specimen were significantly affected by the strain amplitude and simulated PWR environments. The compositions of corrosion products were complexly formed in simulated PWR environments. The porous corrosion surface of pre-corroded materials tended to generate pits as a result of promoting contact area to the fresh metal, which promoted crack initiation. For original materials, the fatigue cracks initiated at inclusions imbedded in the micro-cracks. Moreover, the simulated PWR environments degraded the mechanical properties and low cycle fatigue behavior of 16MND5 specimens remarkably. Pre-corrosion of 16MND5 specimen mainly affected the plastic term of the Coffin-Manson equation.

Coupling model of aerobic waste degradation considering temperature, initial moisture content and air injection volume.

PubMed

Ma, Jun; Liu, Lei; Ge, Sai; Xue, Qiang; Li, Jiangshan; Wan, Yong; Hui, Xinminnan

2018-03-01

A quantitative description of aerobic waste degradation is important in evaluating landfill waste stability and economic management. This research aimed to develop a coupling model to predict the degree of aerobic waste degradation. On the basis of the first-order kinetic equation and the law of conservation of mass, we first developed the coupling model of aerobic waste degradation that considered temperature, initial moisture content and air injection volume to simulate and predict the chemical oxygen demand in the leachate. Three different laboratory experiments on aerobic waste degradation were simulated to test the model applicability. Parameter sensitivity analyses were conducted to evaluate the reliability of parameters. The coupling model can simulate aerobic waste degradation, and the obtained simulation agreed with the corresponding results of the experiment. Comparison of the experiment and simulation demonstrated that the coupling model is a new approach to predict aerobic waste degradation and can be considered as the basis for selecting the economic air injection volume and appropriate management in the future.

Development of the simulation system {open_quotes}IMPACT{close_quotes} for analysis of nuclear power plant severe accidents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Naitoh, Masanori; Ujita, Hiroshi; Nagumo, Hiroichi

1997-07-01

The Nuclear Power Engineering Corporation (NUPEC) has initiated a long-term program to develop the simulation system {open_quotes}IMPACT{close_quotes} for analysis of hypothetical severe accidents in nuclear power plants. IMPACT employs advanced methods of physical modeling and numerical computation, and can simulate a wide spectrum of senarios ranging from normal operation to hypothetical, beyond-design-basis-accident events. Designed as a large-scale system of interconnected, hierarchical modules, IMPACT`s distinguishing features include mechanistic models based on first principles and high speed simulation on parallel processing computers. The present plan is a ten-year program starting from 1993, consisting of the initial one-year of preparatory work followed bymore » three technical phases: Phase-1 for development of a prototype system; Phase-2 for completion of the simulation system, incorporating new achievements from basic studies; and Phase-3 for refinement through extensive verification and validation against test results and available real plant data.« less

Reliance on Simulation in Initial Entry Rifle Marksmanship Training and Future Directions for Simulation

DTIC Science & Technology

2016-11-01

Engagement Simulation Training, and a day of dry -fire. The comparison was conducted during training with iron sights. On the two criterion measures, the...other five days of training consisted of two days of Engagement Skills Trainer (EST) 2000 training, one day of dry -fire, and two days of live-fire...0 / RM1 Preliminary Marksmanship Training Same as Baseline 1 / RM2 EST 2000 (grouping/zeroing) Test-D Drills 2 / RM3 Dry -Fire Training 25m Live-Fire

Identification of the Initial Transient in Discrete-Event Simulation Output Using the Kalman Filter

DTIC Science & Technology

1992-12-01

output vector is obtained from each simulation observation. For example, consider a simulation of a medical clinic that has three types of patients and...determined. The variance of the output P- is derived using Equations (34), (46) and (47): ynt= AVv +,Zn = ± + Hx(tn) + v(t.) (53) = / + ý(t.) + V(tn...residuals fail the hypothesis test approximately 100cl percent of the trials . However, during the transient phase, the data’s relationship in time should be

Laser-induced damage of intrinsic and extrinsic defects by picosecond pulses on multilayer dielectric coatings for petawatt-class lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Negres, Raluca A.; Carr, Christopher W.; Laurence, Ted A.

2016-08-01

Here, we describe a damage testing system and its use in investigating laser-induced optical damage initiated by both intrinsic and extrinsic precursors on multilayer dielectric coatings suitable for use in high-energy, large-aperture petawatt-class lasers. We employ small-area damage test methodologies to evaluate the intrinsic damage resistance of various coatings as a function of deposition methods and coating materials under simulated use conditions. In addition, we demonstrate that damage initiation by raster scanning at lower fluences and growth threshold testing are required to probe the density of extrinsic defects, which will limit large-aperture optics performance.

Electrochemical Testing of Ni-Cr-Mo-Gd Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

T. E. Lister; R. E. Mizia; H. Tian

2005-10-01

The waste package site recommendation design specified a boron-containing stainless steel, Neutronit 976/978, for fabrication of the internal baskets that will be used as a corrosion-resistant neutron-absorbing material. Recent corrosion test results gave higher-than-expected corrosion rates for this material. The material callout for these components has been changed to a Ni-Cr-Mo-Gd alloy (ASTM-B 932-04, UNS N06464) that is being developed at the Idaho National Laboratory. This report discusses the results of initial corrosion testing of this material in simulated in-package environments that could contact the fuel baskets after breach of the waste package outer barrier. The corrosion test matrix wasmore » executed using the potentiodynamic and potentiostatic electrochemical test techniques. The alloy performance shows low rates of general corrosion after initial removal of a gadolinium-rich second phase that intersects the surface. The high halide-containing test solutions exhibited greater tendencies toward initiation of crevice corrosion.« less

Degradation of fifteen emerging contaminants at microg L(-1) initial concentrations by mild solar photo-Fenton in MWTP effluents.

PubMed

Klamerth, N; Rizzo, L; Malato, S; Maldonado, Manuel I; Agüera, A; Fernández-Alba, A R

2010-01-01

The degradation of 15 emerging contaminants (ECs) at low concentrations in simulated and real effluent of municipal wastewater treatment plant with photo-Fenton at unchanged pH and Fe=5 mg L(-1) in a pilot-scale solar CPC reactor was studied. The degradation of those 15 compounds (Acetaminophen, Antipyrine, Atrazine, Caffeine, Carbamazepine, Diclofenac, Flumequine, Hydroxybiphenyl, Ibuprofen, Isoproturon, Ketorolac, Ofloxacin, Progesterone, Sulfamethoxazole and Triclosan), each with an initial concentration of 100 microg L(-1), was found to depend on the presence of CO(3)(2-) and HCO(3)(-) (hydroxyl radicals scavengers) and on the type of water (simulated water, simulated effluent wastewater and real effluent wastewater), but is relatively independent of pH, the type of acid used for release of hydroxyl radicals scavengers and the initial H(2)O(2) concentration used. Toxicity tests with Vibrio fisheri showed that degradation of the compounds in real effluent wastewater led to toxicity increase. (c) 2009 Elsevier Ltd. All rights reserved.

A Hardware-in-the-Loop Simulation Platform for the Verification and Validation of Safety Control Systems

NASA Astrophysics Data System (ADS)

Rankin, Drew J.; Jiang, Jin

2011-04-01

Verification and validation (V&V) of safety control system quality and performance is required prior to installing control system hardware within nuclear power plants (NPPs). Thus, the objective of the hardware-in-the-loop (HIL) platform introduced in this paper is to verify the functionality of these safety control systems. The developed platform provides a flexible simulated testing environment which enables synchronized coupling between the real and simulated world. Within the platform, National Instruments (NI) data acquisition (DAQ) hardware provides an interface between a programmable electronic system under test (SUT) and a simulation computer. Further, NI LabVIEW resides on this remote DAQ workstation for signal conversion and routing between Ethernet and standard industrial signals as well as for user interface. The platform is applied to the testing of a simplified implementation of Canadian Deuterium Uranium (CANDU) shutdown system no. 1 (SDS1) which monitors only the steam generator level of the simulated NPP. CANDU NPP simulation is performed on a Darlington NPP desktop training simulator provided by Ontario Power Generation (OPG). Simplified SDS1 logic is implemented on an Invensys Tricon v9 programmable logic controller (PLC) to test the performance of both the safety controller and the implemented logic. Prior to HIL simulation, platform availability of over 95% is achieved for the configuration used during the V&V of the PLC. Comparison of HIL simulation results to benchmark simulations shows good operational performance of the PLC following a postulated initiating event (PIE).

Collision Avoidance for Airport Traffic Concept Evaluation

NASA Technical Reports Server (NTRS)

Jones, Denise R.; Prinzel, Lawrence J., III; Otero, Sharon D.; Barker, Glover D.

2009-01-01

An initial Collision Avoidance for Airport Traffic (CAAT) concept for the Terminal Maneuvering Area (TMA) was evaluated in a simulation study at the National Aeronautics and Space Administration (NASA) Langley Research Center. CAAT is being designed to enhance surface situation awareness and provide cockpit alerts of potential conflicts during runway, taxi, and low altitude air-to-air operations. The purpose of the study was to evaluate the initial concept for an aircraft-based method of conflict detection and resolution (CD&R) in the TMA focusing on conflict detection algorithms and alerting display concepts. This paper gives an overview of the CD&R concept, simulation study, and test results.

Algorithm for loading shot noise microbunching in multi-dimensional, free-electron laser simulation codes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fawley, William M.

We discuss the underlying reasoning behind and the details of the numerical algorithm used in the GINGER free-electron laser(FEL) simulation code to load the initial shot noise microbunching on the electron beam. In particular, we point out that there are some additional subtleties which must be followed for multi-dimensional codes which are not necessary for one-dimensional formulations. Moreover, requiring that the higher harmonics of the microbunching also be properly initialized with the correct statistics leads to additional complexities. We present some numerical results including the predicted incoherent, spontaneous emission as tests of the shot noise algorithm's correctness.

Mesoscale Modeling, Forecasting and Remote Sensing Research.

DTIC Science & Technology

remote sensing , cyclonic scale diagnostic studies and mesoscale numerical modeling and forecasting are summarized. Mechanisms involved in the release of potential instability are discussed and simulated quantitatively, giving particular attention to the convective formulation. The basic mesoscale model is documented including the equations, boundary condition, finite differences and initialization through an idealized frontal zone. Results of tests including a three dimensional test with real data, tests of convective/mesoscale interaction and tests with a detailed

Thermal Vacuum Facility for Testing Thermal Protection Systems

NASA Technical Reports Server (NTRS)

Daryabeigi, Kamran; Knutson, Jeffrey R.; Sikora, Joseph G.

2002-01-01

A thermal vacuum facility for testing launch vehicle thermal protection systems by subjecting them to transient thermal conditions simulating re-entry aerodynamic heating is described. Re-entry heating is simulated by controlling the test specimen surface temperature and the environmental pressure in the chamber. Design requirements for simulating re-entry conditions are briefly described. A description of the thermal vacuum facility, the quartz lamp array and the control system is provided. The facility was evaluated by subjecting an 18 by 36 in. Inconel honeycomb panel to a typical re-entry pressure and surface temperature profile. For most of the test duration, the average difference between the measured and desired pressures was 1.6% of reading with a standard deviation of +/- 7.4%, while the average difference between measured and desired temperatures was 7.6% of reading with a standard deviation of +/- 6.5%. The temperature non-uniformity across the panel was 12% during the initial heating phase (t less than 500 sec.), and less than 2% during the remainder of the test.

Initial Development of a Quadcopter Simulation Environment for Auralization

NASA Technical Reports Server (NTRS)

Christian, Andrew; Lawrence, Joseph

2016-01-01

This paper describes a recently created computer simulation of quadcopter flight dynamics for the NASA DELIVER project. The goal of this effort is to produce a simulation that includes a number of physical effects that are not usually found in other dynamics simulations (e.g., those used for flight controller development). These effects will be shown to have a significant impact on the fidelity of auralizations - entirely synthetic time-domain predictions of sound - based on this simulation when compared to a recording. High-fidelity auralizations are an important precursor to human subject tests that seek to understand the impact of vehicle configurations on noise and annoyance.

Orion Parachute Riser Cutter Development

NASA Technical Reports Server (NTRS)

Oguz, Sirri; Salazar, Frank

2011-01-01

This paper presents the tests and analytical approach used on the development of a steel riser cutter for the CEV Parachute Assembly System (CPAS) used on the Orion crew module. Figure 1 shows the riser cutter and the steel riser bundle which consists of six individual cables. Due to the highly compressed schedule, initial unavailability of the riser material and the Orion Forward Bay mechanical constraints, JSC primarily relied on a combination of internal ballistics analysis and LS-DYNA simulation for this project. Various one dimensional internal ballistics codes that use standard equation of state and conservation of energy have commonly used in the development of CAD devices for initial first order estimates and as an enhancement to the test program. While these codes are very accurate for propellant performance prediction, they usually lack a fully defined kinematic model for dynamic predictions. A simple piston device can easily and accurately be modeled using an equation of motion. However, the accuracy of analytical models is greatly reduced on more complicated devices with complex external loads, nonlinear trajectories or unique unlocking features. A 3D finite element model of CAD device with all critical features included can vastly improve the analytical ballistic predictions when it is used as a supplement to the ballistic code. During this project, LS-DYNA structural 3D model was used to predict the riser resisting load that was needed for the ballistic code. A Lagrangian model with eroding elements shown in Figure 2 was used for the blade, steel riser and the anvil. The riser material failure strain was fine tuned by matching the dent depth on the anvil with the actual test data. LS-DYNA model was also utilized to optimize the blade tip design for the most efficient cut. In parallel, the propellant type and the amount were determined by using CADPROG internal ballistics code. Initial test results showed a good match with LS-DYNA and CADPROG simulations. Final paper will present a detailed roadmap from initial ballistic modeling and LS-DYNA simulation to the performance testing. Blade shape optimization study will also be presented.

Should tsunami models use a nonzero initial condition for horizontal velocity?

NASA Astrophysics Data System (ADS)

Nava, G.; Lotto, G. C.; Dunham, E. M.

2017-12-01

Tsunami propagation in the open ocean is most commonly modeled by solving the shallow water wave equations. These equations require two initial conditions: one on sea surface height and another on depth-averaged horizontal particle velocity or, equivalently, horizontal momentum. While most modelers assume that initial velocity is zero, Y.T. Song and collaborators have argued for nonzero initial velocity, claiming that horizontal displacement of a sloping seafloor imparts significant horizontal momentum to the ocean. They show examples in which this effect increases the resulting tsunami height by a factor of two or more relative to models in which initial velocity is zero. We test this claim with a "full-physics" integrated dynamic rupture and tsunami model that couples the elastic response of the Earth to the linearized acoustic-gravitational response of a compressible ocean with gravity; the model self-consistently accounts for seismic waves in the solid Earth, acoustic waves in the ocean, and tsunamis (with dispersion at short wavelengths). We run several full-physics simulations of subduction zone megathrust ruptures and tsunamis in geometries with a sloping seafloor, using both idealized structures and a more realistic Tohoku structure. Substantial horizontal momentum is imparted to the ocean, but almost all momentum is carried away in the form of ocean acoustic waves. We compare tsunami propagation in each full-physics simulation to that predicted by an equivalent shallow water wave simulation with varying assumptions regarding initial conditions. We find that the initial horizontal velocity conditions proposed by Song and collaborators consistently overestimate the tsunami amplitude and predict an inconsistent wave profile. Finally, we determine tsunami initial conditions that are rigorously consistent with our full-physics simulations by isolating the tsunami waves (from ocean acoustic and seismic waves) at some final time, and backpropagating the tsunami waves to their initial state by solving the adjoint problem. The resulting initial conditions have negligible horizontal velocity.

Effect of initial delamination on Mode 1 and Mode 2 interlaminar fracture toughness and fatigue fracture threshold

NASA Technical Reports Server (NTRS)

Murri, Gretchen Bostaph; Martin, Roderick H.

1991-01-01

Static and fatigue double-cantilever beam (DCB) and end-notch flexure (ENF) tests were conducted to determine the effect of the simulated initial delamination in interlaminar fracture toughness, G(sub c), and fatigue fracture threshold, G(sub th). Unidirectional, 24-ply specimens of S2/SP250 glass/epoxy were tested using Kapton inserts of four different thickness - 13, 25, 75, and 130 microns, at the midplane at one end, or with tension or shear precracks, to simulate an initial delamination. To determine G(sub c), the fatigue fracture threshold below which no delamination growth would occur in less than 1 x 10(exp 6) cycles, fatigue tests were conducted by cyclically loading specimens until delamination growth was detected. Consistent values of model 1 fracture toughness, G(sub Ic), were measured from DCB specimens with inserts of thickness 75 microns or thinner, or with shear precracks. The fatigue DCB tests gave similar values of G(sub Ith) for the 13, 25, and 75 microns specimens. Results for the shear precracked specimens were significantly lower that for specimens without precracks. Results for both the static and fatigue ENF tests showed that measured G(IIc) and G(IIth) values decreased with decreasing insert thickness, so that no limiting thickness could be determined. Results for specimens with inserts of 75 microns or thicker were significantly higher than the results for precracked specimens or specimens with 13 or 25 microns inserts.

Performance Evaluation of an Actuator Dust Seal for Lunar Operation

NASA Technical Reports Server (NTRS)

Delgado, Irebert R.; Gaier, James R.; Handschuh, Michael; Panko, Scott; Sechkar, Ed

2013-01-01

Exploration of extraterrestrial surfaces (e.g. moon, Mars, asteroid) will require durable space mechanisms that will survive potentially dusty surface conditions in addition to the hard vacuum and extreme temperatures of space. Baseline tests with lunar simulant were recently completed at NASA GRC on a new Low-Temperature Mechanism (LTM) dust seal for space actuator application. Following are top-level findings of the tests completed to date in vacuum using NU-LHT-2M lunar-highlands simulant. A complete set of findings are found in the conclusions section.Tests were run at approximately 10-7 torr with unidirectional rotational speed of 39 RPM.Initial break-in runs were performed at atmospheric conditions with no simulant. During the break-in runs, the maximum torque observed was 16.7 lbf-in. while the maximum seal outer diameter temperature was 103F. Only 0.4 milligrams of NU-LHT-2M simulant passed through the sealshaft interface in the first 511,000 cycles while under vacuum despite a chip on the secondary sealing surface.Approximately 650,000 of a planned 1,000,000 cycles were completed in vacuum with NU-LHT-2M simulant.Upon test disassembly NU-LHT-2M was found on the secondary sealing surface.

Quality measures for the management of hydrocephalus: concepts, simulations, and preliminary field-testing.

PubMed

Barton, Spencer E; Campbell, Jeffrey W; Piatt, Joseph H

2013-04-01

The authors define and examine the properties of 2 new, practice-based quality measures for the management of hydrocephalus. The Surgical Activity Rate (SAR) is defined as the number of definitive operations for the treatment of hydrocephalus performed in a neurosurgical practice over the course of a year, divided by the number of patients with hydrocephalus seen in follow-up during that year. The Revision Quotient (RQ) is defined as the number of definitive revision operations performed in a neurosurgical practice in the course of a year, divided by the number of definitive initial operations during that year for patients with newly diagnosed hydrocephalus. Using published actuarial shunt survival data, the authors conducted Monte Carlo simulations of a pediatric neurosurgical practice to illustrate the properties and interpretations of the SAR and RQ. They used data from the Kids' Inpatient Database (KID) for 2009 to calculate RQs for hospitals accounting for more than 10 admissions coded for initial CSF shunt insertions. During the initial growth phase of a simulated neurosurgical practice, the SAR approached its steady-state value much earlier than the RQ. Both measures were sensitive to doubling or halving of monthly failure rates. In the 2009 KID, 117 hospitals reported more than 10 initial shunt insertions. The weighted mean (± standard deviation) RQ for these hospitals was 1.79 ± 0.69. Among hospitals performing 50 or more initial shunt insertions, the RQ ranged between 0.71 and 3.65. The SAR and RQ have attractive qualitative features as practice-based quality measures. The RQ, at least, exhibits clinically meaningful interhospital variation as applied to CSF shunt surgery. The SAR and RQ merit prospective field-testing as measures of quality in the management of childhood hydrocephalus.

Microstructural Effects on SCC Initiation PWR Primary Water Cold-Worked Alloy 600

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhai, Ziqing; Toloczko, Mychailo B.; Bruemmer, Stephen M.

SCC initiation behavior of one mill annealed alloy 600 plate heat was investigated in simulated PWR primary water under constant load at yield stress with in-situ direct current potential drop (DCPD) monitoring for crack initiation. Twelve specimens were tested at similar cold work levels among which three showed much shorter SCC initiation times (<400 hrs) than the others (>1200 hrs). Post-test examinations revealed that these three specimens all feature an inhomogeneous microstructure where the primary crack always nucleated along the boundary of large elongated grains protruding normally into the gauge. In contrast, such microstructure was either not observed or didmore » not extend deep enough into the gauge in the other specimens exhibiting ~3-6X longer initiation times. In order to better understand the role of this microstructural inhomogeneity in SCC initiation, high-resolution microscopy was performed to compare carbide morphology and strain distribution between the long grains and normal grains, and their potential effects on SCC initiation are discussed in this paper.« less

Simulator study of the stall departure characteristics of a light general aviation airplane with and without a wing-leading-edge modification

NASA Technical Reports Server (NTRS)

Riley, D. R.

1985-01-01

A six-degree-of-freedom nonlinear simulation was developed for a two-place, single-engine, low-wing general aviation airplane for the stall and initial departure regions of flight. Two configurations, one with and one without an outboard wing-leading-edge modification, were modeled. The math models developed are presented simulation predictions and flight-test data for validation purposes and simulation results for the two configurations for various maneuvers and power settings are compared to show the beneficial influence of adding the wing-leading-edge modification.

Resource Prospector Propulsion Cold Flow Test

NASA Technical Reports Server (NTRS)

Williams, Hunter; Pederson, Kevin; Dervan, Melanie; Holt, Kimberly; Jernigan, Frankie; Trinh, Huu; Flores, Sam

2014-01-01

For the past year, NASA Marshall Space Flight Center and Johnson Space Center have been working on a government version of a lunar lander design for the Resource Prospector Mission. A propulsion cold flow test system, representing an early flight design of the propulsion system, has been fabricated. The primary objective of the cold flow test is to simulate the Resource Prospector propulsion system operation through water flow testing and obtain data for anchoring analytical models. This effort will also provide an opportunity to develop a propulsion system mockup to examine hardware integration to a flight structure. This paper will report the work progress of the propulsion cold flow test system development and test preparation. At the time this paper is written, the initial waterhammer testing is underway. The initial assessment of the test data suggests that the results are as expected and have a similar trend with the pretest prediction. The test results will be reported in a future conference.

Molecular simulation study of cavity-generated instabilities in the superheated Lennard-Jones liquid

NASA Astrophysics Data System (ADS)

Torabi, Korosh; Corti, David S.

2010-10-01

Previous equilibrium-based density-functional theory (DFT) analyses of cavity formation in the pure component superheated Lennard-Jones (LJ) liquid [S. Punnathanam and D. S. Corti, J. Chem. Phys. 119, 10224 (2003); M. J. Uline and D. S. Corti, Phys. Rev. Lett. 99, 076102 (2007)] revealed that a thermodynamic limit of stability appears in which no liquidlike density profile can develop for cavity radii greater than some critical size (being a function of temperature and bulk density). The existence of these stability limits was also verified using isothermal-isobaric Monte Carlo (MC) simulations. To test the possible relevance of these limits of stability to a dynamically evolving system, one that may be important for homogeneous bubble nucleation, we perform isothermal-isobaric molecular dynamics (MD) simulations in which cavities of different sizes are placed within the superheated LJ liquid. When the impermeable boundary utilized to generate a cavity is removed, the MD simulations show that the cavity collapses and the overall density of the system remains liquidlike, i.e., the system is stable, when the initial cavity radius is below some certain value. On the other hand, when the initial radius is large enough, the cavity expands and the overall density of the system rapidly decreases toward vaporlike densities, i.e., the system is unstable. Unlike the DFT predictions, however, the transition between stability and instability is not infinitely sharp. The fraction of initial configurations that generate an instability (or a phase separation) increases from zero to unity as the initial cavity radius increases over a relatively narrow range of values, which spans the predicted stability limit obtained from equilibrium MC simulations. The simulation results presented here provide initial evidence that the equilibrium-based stability limits predicted in the previous DFT and MC simulation studies may play some role, yet to be fully determined, in the homogeneous nucleation and growth of embryos within metastable fluids.

The influence of Monte Carlo source parameters on detector design and dose perturbation in small field dosimetry

NASA Astrophysics Data System (ADS)

Charles, P. H.; Crowe, S. B.; Kairn, T.; Knight, R.; Hill, B.; Kenny, J.; Langton, C. M.; Trapp, J. V.

2014-03-01

To obtain accurate Monte Carlo simulations of small radiation fields, it is important model the initial source parameters (electron energy and spot size) accurately. However recent studies have shown that small field dosimetry correction factors are insensitive to these parameters. The aim of this work is to extend this concept to test if these parameters affect dose perturbations in general, which is important for detector design and calculating perturbation correction factors. The EGSnrc C++ user code cavity was used for all simulations. Varying amounts of air between 0 and 2 mm were deliberately introduced upstream to a diode and the dose perturbation caused by the air was quantified. These simulations were then repeated using a range of initial electron energies (5.5 to 7.0 MeV) and electron spot sizes (0.7 to 2.2 FWHM). The resultant dose perturbations were large. For example 2 mm of air caused a dose reduction of up to 31% when simulated with a 6 mm field size. However these values did not vary by more than 2 % when simulated across the full range of source parameters tested. If a detector is modified by the introduction of air, one can be confident that the response of the detector will be the same across all similar linear accelerators and the Monte Carlo modelling of each machine is not required.

A New Tribological Test for Candidate Brush Seal Materials Evaluation

NASA Technical Reports Server (NTRS)

Fellenstein, James A.; Dellacorte, Christopher

1994-01-01

A new tribological test for candidate brush seal materials evaluation has been developed. The sliding contact between the brush seal wires and their mating counterface journal is simulated by testing a small tuft of wire against the outside diameter of a high speed rotating shaft. The test configuration is similar to a standard block on ring geometry. The new tester provides the capability to measure both the friction and wear of candidate wire and counterface materials under controlled loading conditions in the gram to kilogram range. A wide test condition latitude of speeds (1 to 27 m/s), temperatures (25 to 700 C), and loads (0.5 to 10 N) enables the simulation of many of the important tribological parameters found in turbine engine brush seals. This paper describes the new test rig and specimen configuration and presents initial data for candidate seal materials comparing tuft test results and wear surface morphology to field tested seal components.

Using Numerical Modeling to Simulate Space Capsule Ground Landings

NASA Technical Reports Server (NTRS)

Heymsfield, Ernie; Fasanella, Edwin L.

2009-01-01

Experimental work is being conducted at the National Aeronautics and Space Administration s (NASA) Langley Research Center (LaRC) to investigate ground landing capabilities of the Orion crew exploration vehicle (CEV). The Orion capsule is NASA s replacement for the Space Shuttle. The Orion capsule will service the International Space Station and be used for future space missions to the Moon and to Mars. To evaluate the feasibility of Orion ground landings, a series of capsule impact tests are being performed at the NASA Langley Landing and Impact Research Facility (LandIR). The experimental results derived at LandIR provide means to validate and calibrate nonlinear dynamic finite element models, which are also being developed during this study. Because of the high cost and time involvement intrinsic to full-scale testing, numerical simulations are favored over experimental work. Subsequent to a numerical model validated by actual test responses, impact simulations will be conducted to study multiple impact scenarios not practical to test. Twenty-one swing tests using the LandIR gantry were conducted during the June 07 through October 07 time period to evaluate the Orion s impact response. Results for two capsule initial pitch angles, 0deg and -15deg , along with their computer simulations using LS-DYNA are presented in this article. A soil-vehicle friction coefficient of 0.45 was determined by comparing the test stopping distance with computer simulations. In addition, soil modeling accuracy is presented by comparing vertical penetrometer impact tests with computer simulations for the soil model used during the swing tests.

Design of Bi-Directional Hydrofoils for Tidal Current Turbines

NASA Astrophysics Data System (ADS)

Nedyalkov, Ivaylo; Wosnik, Martin

2015-11-01

Tidal Current Turbines operate in flows which reverse direction. Bi-directional hydrofoils have rotational symmetry and allow such turbines to operate without the need for pitch or yaw control, decreasing the initial and maintenance costs. A numerical test-bed was developed to automate the simulations of hydrofoils in OpenFOAM and was utilized to simulate the flow over eleven classes of hydrofoils comprising a total of 700 foil shapes at different angles of attack. For promising candidate foil shapes physical models of 75 mm chord and 150 mm span were fabricated and tested in the University of New Hampshire High-Speed Cavitation Tunnel (HiCaT). The experimental results were compared to the simulations for model validation. The numerical test-bed successfully generated simulations for a wide range of foil shapes, although, as expected, the k - ω - SST turbulence model employed here was not adequate for some of the foils and for large angles of attack at which separation occurred. An optimization algorithm is currently being coupled with the numerical test-bed and additional turbulence models will be implemented in the future.

Initial CGE Model Results Summary Exogenous and Endogenous Variables Tests

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edwards, Brian Keith; Boero, Riccardo; Rivera, Michael Kelly

The following discussion presents initial results of tests of the most recent version of the National Infrastructure Simulation and Analysis Center Dynamic Computable General Equilibrium (CGE) model developed by Los Alamos National Laboratory (LANL). The intent of this is to test and assess the model’s behavioral properties. The test evaluated whether the predicted impacts are reasonable from a qualitative perspective. This issue is whether the predicted change, be it an increase or decrease in other model variables, is consistent with prior economic intuition and expectations about the predicted change. One of the purposes of this effort is to determine whethermore » model changes are needed in order to improve its behavior qualitatively and quantitatively.« less

A study to define an in-flight dynamics measurement and data applications program for space shuttle payloads

NASA Technical Reports Server (NTRS)

Rader, W. P.; Barrett, S.; Payne, K. R.

1975-01-01

Data measurement and interpretation techniques were defined for application to the first few space shuttle flights, so that the dynamic environment could be sufficiently well established to be used to reduce the cost of future payloads through more efficient design and environmental test techniques. It was concluded that: (1) initial payloads must be given comprehensive instrumentation coverage to obtain detailed definition of acoustics, vibration, and interface loads, (2) analytical models of selected initial payloads must be developed and verified by modal surveys and flight measurements, (3) acoustic tests should be performed on initial payloads to establish realistic test criteria for components and experiments in order to minimize unrealistic failures and retest requirements, (4) permanent data banks should be set up to establish statistical confidence in the data to be used, (5) a more unified design/test specification philosophy is needed, (6) additional work is needed to establish a practical testing technique for simulation of vehicle transients.

2-kW Solar Dynamic Space Power System Tested in Lewis' Thermal Vacuum Facility

NASA Technical Reports Server (NTRS)

1995-01-01

Working together, a NASA/industry team successfully operated and tested a complete solar dynamic space power system in a large thermal vacuum facility with a simulated sun. This NASA Lewis Research Center facility, known as Tank 6 in building 301, accurately simulates the temperatures, high vacuum, and solar flux encountered in low-Earth orbit. The solar dynamic space power system shown in the photo in the Lewis facility, includes the solar concentrator and the solar receiver with thermal energy storage integrated with the power conversion unit. Initial testing in December 1994 resulted in the world's first operation of an integrated solar dynamic system in a relevant environment.

Stress corrosion crack initiation of alloy 600 in PWR primary water

DOE PAGES

Zhai, Ziqing; Toloczko, Mychailo B.; Olszta, Matthew J.; ...

2017-04-27

Stress corrosion crack (SCC) initiation of three mill-annealed alloy 600 heats in simulated pressurized water reactor primary water has been investigated using constant load tests equipped with in-situ direct current potential drop (DCPD) measurement capabilities. SCC initiation times were greatly reduced by a small amount of cold work. Shallow intergranular attack and/or cracks were found on most high-energy grain boundaries intersecting the surface with only a small fraction evolving into larger cracks and intergranular SCC growth. Crack depth profiles were measured and related to DCPD-detected initiation response. Lastly, we discuss processes controlling the SCC initiation in mill-annealed alloy 600.

Stress corrosion crack initiation of alloy 600 in PWR primary water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhai, Ziqing; Toloczko, Mychailo B.; Olszta, Matthew J.

Stress corrosion crack (SCC) initiation of three mill-annealed alloy 600 heats in simulated pressurized water reactor primary water has been investigated using constant load tests equipped with in-situ direct current potential drop (DCPD) measurement capabilities. SCC initiation times were greatly reduced by a small amount of cold work. Shallow intergranular attack and/or cracks were found on most high-energy grain boundaries intersecting the surface with only a small fraction evolving into larger cracks and intergranular SCC growth. Crack depth profiles were measured and related to DCPD-detected initiation response. Lastly, we discuss processes controlling the SCC initiation in mill-annealed alloy 600.

The Mission Planning Lab: A Visualization and Analysis Tool

NASA Technical Reports Server (NTRS)

Daugherty, Sarah C.; Cervantes, Benjamin W.

2009-01-01

Simulation and visualization are powerful decision making tools that are time-saving and cost-effective. Space missions pose testing and e valuation challenges that can be overcome through modeling, simulatio n, and visualization of mission parameters. The National Aeronautics and Space Administration?s (NASA) Wallops Flight Facility (WFF) capi talizes on the benefits of modeling, simulation, and visualization to ols through a project initiative called The Mission Planning Lab (MPL ).

A Novel Method to Simulate the Progression of Collagen Degeneration of Cartilage in the Knee: Data from the Osteoarthritis Initiative

NASA Astrophysics Data System (ADS)

Mononen, Mika E.; Tanska, Petri; Isaksson, Hanna; Korhonen, Rami K.

2016-02-01

We present a novel algorithm combined with computational modeling to simulate the development of knee osteoarthritis. The degeneration algorithm was based on excessive and cumulatively accumulated stresses within knee joint cartilage during physiological gait loading. In the algorithm, the collagen network stiffness of cartilage was reduced iteratively if excessive maximum principal stresses were observed. The developed algorithm was tested and validated against experimental baseline and 4-year follow-up Kellgren-Lawrence grades, indicating different levels of cartilage degeneration at the tibiofemoral contact region. Test groups consisted of normal weight and obese subjects with the same gender and similar age and height without osteoarthritic changes. The algorithm accurately simulated cartilage degeneration as compared to the Kellgren-Lawrence findings in the subject group with excess weight, while the healthy subject group’s joint remained intact. Furthermore, the developed algorithm followed the experimentally found trend of cartilage degeneration in the obese group (R2 = 0.95, p < 0.05 experiments vs. model), in which the rapid degeneration immediately after initiation of osteoarthritis (0-2 years, p < 0.001) was followed by a slow or negligible degeneration (2-4 years, p > 0.05). The proposed algorithm revealed a great potential to objectively simulate the progression of knee osteoarthritis.

Pretest analysis document for Test S-FS-6

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shaw, R.A.; Hall, D.G.

This report documents the pretest analyses completed for Semiscale Test S-FS-6. This test will simulate a transient initiated by a 100% break in a steam generator bottom feedwater line downstream of the check valve. The initial conditions represent normal operating conditions for a C-E System 80 nuclear power plant. Predictions of transients resulting from feedwater line breaks in these plants have indicated that significant primary system overpressurization may occur. The enclosed analyses include a RELAP5/MOD2/CY21 code calculation and preliminary results from a facility hot, integrated test which was conducted to near S-FS-6 specifications. The results of these analyses indicate thatmore » the test objectives for Test S-FS-6 can be achieved. The primary system overpressurization will pose no threat to personnel or plant integrity.« less

An Engineering Methodology for Implementing and Testing VLSI (Very Large Scale Integrated) Circuits

DTIC Science & Technology

1989-03-01

the pad frame and associated routing, conducted additional testing. and submitted the finished design effort to MOSIS for manufacturing. Throughout...register bank TSTCON Allows the XNOR circuitry to enter the TEST register bank PADIN Test signal to check operation of the input pad VCC Power connection...MOSSIM II simulation program. but the design offered little observability within the circuit. The initial design used 35 pins of a 40 pin pad frame

Evaluation of approaches focused on modelling of organic carbon stocks using the RothC model

NASA Astrophysics Data System (ADS)

Koco, Štefan; Skalský, Rastislav; Makovníková, Jarmila; Tarasovičová, Zuzana; Barančíková, Gabriela

2014-05-01

The aim of current efforts in the European area is the protection of soil organic matter, which is included in all relevant documents related to the protection of soil. The use of modelling of organic carbon stocks for anticipated climate change, respectively for land management can significantly help in short and long-term forecasting of the state of soil organic matter. RothC model can be applied in the time period of several years to centuries and has been tested in long-term experiments within a large range of soil types and climatic conditions in Europe. For the initialization of the RothC model, knowledge about the carbon pool sizes is essential. Pool size characterization can be obtained from equilibrium model runs, but this approach is time consuming and tedious, especially for larger scale simulations. Due to this complexity we search for new possibilities how to simplify and accelerate this process. The paper presents a comparison of two approaches for SOC stocks modelling in the same area. The modelling has been carried out on the basis of unique input of land use, management and soil data for each simulation unit separately. We modeled 1617 simulation units of 1x1 km grid on the territory of agroclimatic region Žitný ostrov in the southwest of Slovakia. The first approach represents the creation of groups of simulation units based on the evaluation of results for simulation unit with similar input values. The groups were created after the testing and validation of modelling results for individual simulation units with results of modelling the average values of inputs for the whole group. Tests of equilibrium model for interval in the range 5 t.ha-1 from initial SOC stock showed minimal differences in results comparing with result for average value of whole interval. Management inputs data from plant residues and farmyard manure for modelling of carbon turnover were also the same for more simulation units. Combining these groups (intervals of initial SOC stock, groups of plant residues inputs, groups of farmyard manure inputs), we created 661 simulation groups. Within the group, for all simulation units we used average values of inputs. Export of input data and modelling has been carried out manually in the graphic environment of RothC 26.3 v2.0 application for each group separately. SOC stocks were modeled for 661 groups of simulation units. For the second possibility we used RothC 26.3 version for DOS. The inputs for modelling were exported using VBA scripts in the environment of MS Access program. Equilibrium modelling for more variations of plant residues inputs was performed. Subsequently we selected the nearest value of total pool size to the real initial SOC stock value. All simulation units (1617) were automatically modeled by means of the predefined Batch File. The comparison of two methods of modelling showed spatial differentiation of results mainly with the increasing time of modelling period. In the time sequence, from initial period we mark the increasing the number of simulation units with differences in SOC stocks according to selected approaches. Observed differences suggest that the results of modelling obtained by inputs generalization should be taken into account with a certain degree of reserve. At large scales simulations it is more appropriate to use the DOS version of RothC 26.3 model which allows automated modelling. This reduces the time needed for model operation, without the necessity to look for the possibilities of minimizing the simulated units. Key words Soil organic carbon stock, modelling, RothC 26.3, agricultural soils, Slovakia Acknowledgements This work was supported by the Slovak Research and Development Agency under the contract No. APVV-0580-10 and APVV-0131-11.

Experimental performance of an ablative material as an external insulator for a hypersonic research aircraft

NASA Technical Reports Server (NTRS)

Puster, R. L.; Chapman, A. J.

1977-01-01

An ablative material composed of silica-filled elastomeric silicone was tested to evaluate its thermal and structural performance as an external insulator, or heat shield, for a hypersonic research aircraft. The material was also tested to determine whether it would form a durable char layer when initially heated and thereafter function primarily as an insulator with little further pyrolysis or char removal. Aerothermal tests were representative of nominal Mach 6 cruise conditions of the aircraft, and additional tests were representative of Mach 8 cruise and interference heating conditions. Radiant heating tests were used to simulate the complete nominal Mach 6 surface-temperature history. The silica char that formed during aerothermal tests was not durable. The char experienced a general and preferential surface recession, with the primary mechanism for char removal being erosion. Tests revealed that radiant heating is not a valid technique for simulating aerodynamic heating of the material.

The Impact of TRMM on Mesoscale Model Simulation of Super Typhoon Paka

NASA Technical Reports Server (NTRS)

Tao, W.-K.; Jia, Y.; Halverson, J.; Hou, A.; Olson, W.; Rodgers, E.; Simpson, J.

1999-01-01

Tropical cyclone Paka formed during the first week of December 1997 and underwent three periods of rapid intensification over the following two weeks. During one of these periods, which initiated early on December 10, Paka's Dvorak-measured windspeed increased from 23 to 60 m/s over a 48-hr period. On December 18, during the last rapid deepening episode, Paka became a supertyphoon with a maximum wind speed of about 80 m/s. In this study, the Penn State/NCAR Mesoscale Model (MM5) with improved physics (i.e., cloud microphysics, radiation, land-soil-vegetation-surface processes, and TOGA COARE flux scheme) and a multiple level nesting technique (135, 45 and 15 km horizontal resolution) will be used to simulate supertyphoon Paka. We performed two runs initialized with Goddard Earth Observing System (GEOS) data sets. The first GEOS data set does not incorporate either TRMM (tropical rainfall measuring mission satellite) or SSM/I (sensor microwave imager) observed rainfall fields into the GEOS's assimilation system while the second one does. Preliminary results show that the MM5 simulated surface pressure deepened by more than 25 mb (45 km resolution domain) in the run initialized with the GEOS data set incorporating TRMM and SSM/I derived rainfall, compared to the one initialized without. However, the track and precipitation patterns are quite similar between the runs. In our presentation, we will show the impact of TRMM rainfall upon the MM5 simulation of Paka at various horizontal resolutions. We will also examine the physical processes associated with initial explosive development by comparing MM5 simulated rainfall and latent heat release. In addition, budget (vorticity, PV, momentum and heat) calculations and sensitivity tests will be performed to examine the upper-tropospheric and SST mechanisms responsible for the explosive development of Paka.

Development and initial test of the University of Wisconsin global isentropic-sigma model

NASA Technical Reports Server (NTRS)

Zapotocny, Tom H.; Johnson, Donald R.; Reames, Fred M.

1994-01-01

The description of a global version of the University of Wisconsin (UW) hybrid isentropic-sigma (theta-sigma) model and the results from an initial numerical weather prediction experiment are presented in this paper. The main objectives of this initial test are to (1) discuss theta-sigma model development and computer requirements, (2) demonstrate the ability of the UW theta-sigma model for global numerical weather prediction using realistic orography and parameterized physical processes, and (3) compare the transport of an inert trace constituent against a nominally 'identical' sigma coordinate model. Initial and verifying data for the 5-day simulations presented in this work were supplied by the Goddard Earth Observing System (GEOS-1) data assimilation system. The time period studied is 1-6 February 1985. This validation experiment demonstrates that the global UW theta-sigma model produces a realistic 5-day simulation of the mass and momentum distributions when compared to both the identical sigma model and GEOS-1 verification. Root-mean-square errors demonstrate that the theta-sigma model is slightly more accurate than the nominally identical sigma model with respect to standard synoptic variables. Of particular importance, the UW theta-sigma model displays a distinct advantage over the conventional sigma model with respect to the prognostic simulation of inert trace constituent transport in amplifying baroclinic waves of the extratropics. This is especially true in the upper troposphere and stratosphere where the spatial integrity and conservation of an inert trace constituent is severely compromised in the sigma model compared to the theta-sigma model.

Experimental and analytical studies of advanced air cushion landing systems

NASA Technical Reports Server (NTRS)

Lee, E. G. S.; Boghani, A. B.; Captain, K. M.; Rutishauser, H. J.; Farley, H. L.; Fish, R. B.; Jeffcoat, R. L.

1981-01-01

Several concepts are developed for air cushion landing systems (ACLS) which have the potential for improving performance characteristics (roll stiffness, heave damping, and trunk flutter), and reducing fabrication cost and complexity. After an initial screening, the following five concepts were evaluated in detail: damped trunk, filled trunk, compartmented trunk, segmented trunk, and roll feedback control. The evaluation was based on tests performed on scale models. An ACLS dynamic simulation developed earlier is updated so that it can be used to predict the performance of full-scale ACLS incorporating these refinements. The simulation was validated through scale-model tests. A full-scale ACLS based on the segmented trunk concept was fabricated and installed on the NASA ACLS test vehicle, where it is used to support advanced system development. A geometrically-scaled model (one third full scale) of the NASA test vehicle was fabricated and tested. This model, evaluated by means of a series of static and dynamic tests, is used to investigate scaling relationships between reduced and full-scale models. The analytical model developed earlier is applied to simulate both the one third scale and the full scale response.

Development of a Test Facility for Air Revitalization Technology Evaluation

NASA Technical Reports Server (NTRS)

Lu, Sao-Dung; Lin, Amy; Campbell, Melissa; Smith, Frederick; Curley, Su

2007-01-01

Development of new air revitalization system (ARS) technology can initially be performed in a subscale laboratory environment, but in order to advance the maturity level, the technology must be tested in an end-to-end integrated environment. The Air Revitalization Technology Evaluation Facility (ARTEF) at the NASA Johnson Space Center serves as a ground test bed for evaluating emerging ARS technologies in an environment representative of spacecraft atmospheres. At the center of the ARTEF is a hypobaric chamber which serves as a sealed atmospheric chamber for closed loop testing. A Human Metabolic Simulator (HMS) was custom-built to simulate the consumption of oxygen, and production of carbon dioxide, moisture and heat of up to eight persons. A multitude of gas analyzers and dew point sensors are used to monitor the chamber atmosphere upstream and downstream of a test article. A robust vacuum system is needed to simulate the vacuum of space. A reliable data acquisition and control system is required to connect all the subsystems together. This paper presents the capabilities of the integrated test facility and some of the issues encountered during the integration.

Compression of thick laminated composite beams with initial impact-like damage

NASA Technical Reports Server (NTRS)

Breivik, N. L.; Guerdal, Z.; Griffin, O. H., Jr.

1992-01-01

While the study of compression after impact of laminated composites has been under consideration for many years, the complexity of the damage initiated by low velocity impact has not lent itself to simple predictive models for compression strength. The damage modes due to non-penetrating, low velocity impact by large diameter objects can be simulated using quasi-static three-point bending. The resulting damage modes are less coupled and more easily characterized than actual impact damage modes. This study includes the compression testing of specimens with well documented initial damage states obtained from three-point bend testing. Compression strengths and failure modes were obtained for quasi-isotropic stacking sequences from 0.24 to 1.1 inches thick with both grouped and interspersed ply stacking. Initial damage prior to compression testing was divided into four classifications based on the type, extent, and location of the damage. These classifications are multiple through-thickness delaminations, isolated delamination, damage near the surface, and matrix cracks. Specimens from each classification were compared to specimens tested without initial damage in order to determine the effects of the initial damage on the final compression strength and failure modes. A finite element analysis was used to aid in the understanding and explanation of the experimental results.

MSFC Three Point Docking Mechanism design review

NASA Technical Reports Server (NTRS)

Schaefer, Otto; Ambrosio, Anthony

1992-01-01

In the next few decades, we will be launching expensive satellites and space platforms that will require recovery for economic reasons, because of initial malfunction, servicing, repairs, or out of a concern for post lifetime debris removal. The planned availability of a Three Point Docking Mechanism (TPDM) is a positive step towards an operational satellite retrieval infrastructure. This study effort supports NASA/MSFC engineering work in developing an automated docking capability. The work was performed by the Grumman Space & Electronics Group as a concept evaluation/test for the Tumbling Satellite Retrieval Kit. Simulation of a TPDM capture was performed in Grumman's Large Amplitude Space Simulator (LASS) using mockups of both parts (the mechanism and payload). Similar TPDM simulation activities and more extensive hardware testing was performed at NASA/MSFC in the Flight Robotics Laboratory and Space Station/Space Operations Mechanism Test Bed (6-DOF Facility).

Aerodynamic design and optimization of high altitude environment simulation system based on CFD

NASA Astrophysics Data System (ADS)

Ma, Pingchang; Yan, Lutao; Li, Hong

2017-05-01

High altitude environment simulation system (HAES) is built to provide a true flight environment for subsonic vehicles, with low density, high speed, and short time characteristics. Normally, wind tunnel experiments are based on similar principal, such as parameters of Re or Ma, in order to shorten test product size. However, the test products in HAES are trim size, so more attention is put on the true flight environment simulation. It includes real flight environment pressure, destiny and real flight velocity, and its type velocity is Ma=0.8. In this paper, the aerodynamic design of HAES is introduced and its rationality is explained according to CFD calculation based on Fluent. Besides, the initial pressure of vacuum tank in HAES is optimized, which is not only to meet the economic requirements, but also to decrease the effect of additional stress on the test product in the process of the establishment of the target flow field.

Characterizing Fracturing of Clay-Rich Lower Watrous Rock: From Laboratory Experiments to Nonlocal Damage-Based Simulations

NASA Astrophysics Data System (ADS)

Guy, N.; Seyedi, D. M.; Hild, F.

2018-06-01

The work presented herein aims at characterizing and modeling fracturing (i.e., initiation and propagation of cracks) in a clay-rich rock. The analysis is based on two experimental campaigns. The first one relies on a probabilistic analysis of crack initiation considering Brazilian and three-point flexural tests. The second one involves digital image correlation to characterize crack propagation. A nonlocal damage model based on stress regularization is used for the simulations. Two thresholds both based on regularized stress fields are considered. They are determined from the experimental campaigns performed on Lower Watrous rock. The results obtained with the proposed approach are favorably compared with the experimental results.

Initial state with shear in peripheral heavy ion collisions

NASA Astrophysics Data System (ADS)

Magas, V. K.; Gordillo, J.; Strottman, D.; Xie, Y. L.; Csernai, L. P.

2018-06-01

In the present work we propose a new way of constructing the initial state for further hydrodynamic simulation of relativistic heavy ion collisions based on Bjorken-like solution applied streak by streak in the transverse plane. Previous fluid dynamical calculations in Cartesian coordinates with an initial state based on a streak by streak Yang-Mills field led for peripheral higher energy collisions to large angular momentum, initial shear flow and significant local vorticity. Recent experiments verified the existence of this vorticity via the resulting polarization of emitted Λ and Λ ¯ particles. At the same time parton cascade models indicated the existence of more compact initial state configurations, which we are going to simulate in our approach. The proposed model satisfies all the conservation laws, including conservation of a strong initial angular momentum, which is present in noncentral collisions. As a consequence of this large initial angular momentum we observe the rotation of the whole system as well as the fluid shear in the initial state, which leads to large flow vorticity. Another advantage of the proposed model is that the initial state can be given in both [t,x,y,z] and [τ ,x ,y ,η ] coordinates and thus can be tested by all 3+1D hydrodynamical codes which exist in the field.

CORBASec Used to Secure Distributed Aerospace Propulsion Simulations

NASA Technical Reports Server (NTRS)

Blaser, Tammy M.

2003-01-01

The NASA Glenn Research Center and its industry partners are developing a Common Object Request Broker (CORBA) Security (CORBASec) test bed to secure their distributed aerospace propulsion simulations. Glenn has been working with its aerospace propulsion industry partners to deploy the Numerical Propulsion System Simulation (NPSS) object-based technology. NPSS is a program focused on reducing the cost and time in developing aerospace propulsion engines. It was developed by Glenn and is being managed by the NASA Ames Research Center as the lead center reporting directly to NASA Headquarters' Aerospace Technology Enterprise. Glenn is an active domain member of the Object Management Group: an open membership, not-for-profit consortium that produces and manages computer industry specifications (i.e., CORBA) for interoperable enterprise applications. When NPSS is deployed, it will assemble a distributed aerospace propulsion simulation scenario from proprietary analytical CORBA servers and execute them with security afforded by the CORBASec implementation. The NPSS CORBASec test bed was initially developed with the TPBroker Security Service product (Hitachi Computer Products (America), Inc., Waltham, MA) using the Object Request Broker (ORB), which is based on the TPBroker Basic Object Adaptor, and using NPSS software across different firewall products. The test bed has been migrated to the Portable Object Adaptor architecture using the Hitachi Security Service product based on the VisiBroker 4.x ORB (Borland, Scotts Valley, CA) and on the Orbix 2000 ORB (Dublin, Ireland, with U.S. headquarters in Waltham, MA). Glenn, GE Aircraft Engines, and Pratt & Whitney Aircraft are the initial industry partners contributing to the NPSS CORBASec test bed. The test bed uses Security SecurID (RSA Security Inc., Bedford, MA) two-factor token-based authentication together with Hitachi Security Service digital-certificate-based authentication to validate the various NPSS users. The test bed is expected to demonstrate NPSS CORBASec-specific policy functionality, confirm adequate performance, and validate the required Internet configuration in a distributed collaborative aerospace propulsion environment.

Evaluation of filter fabrics for use in silt fences.

DOT National Transportation Integrated Search

1980-01-01

The study reported was initiated to develop tests simulating field conditions that could be used to develop information for the formulation of specifications for use in purchasing filter fabrics to be used to construct silt fences. Fifteen fabrics we...

International Energy Agency Ocean Energy Systems Task 10 Wave Energy Converter Modeling Verification and Validation: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wendt, Fabian F; Yu, Yi-Hsiang; Nielsen, Kim

This is the first joint reference paper for the Ocean Energy Systems (OES) Task 10 Wave Energy Converter modeling verification and validation group. The group is established under the OES Energy Technology Network program under the International Energy Agency. OES was founded in 2001 and Task 10 was proposed by Bob Thresher (National Renewable Energy Laboratory) in 2015 and approved by the OES Executive Committee EXCO in 2016. The kickoff workshop took place in September 2016, wherein the initial baseline task was defined. Experience from similar offshore wind validation/verification projects (OC3-OC5 conducted within the International Energy Agency Wind Task 30)more » [1], [2] showed that a simple test case would help the initial cooperation to present results in a comparable way. A heaving sphere was chosen as the first test case. The team of project participants simulated different numerical experiments, such as heave decay tests and regular and irregular wave cases. The simulation results are presented and discussed in this paper.« less

Shuttle avionics software development trials: Tribulations and successes, the backup flight system

NASA Technical Reports Server (NTRS)

Chevers, E. S.

1985-01-01

The development and verification of the Backup Flight System software (BFS) is discussed. The approach taken for the BFS was to develop a very simple and straightforward software program and then test it in every conceivable manner. The result was a program that contained approximately 12,000 full words including ground checkout and the built in test program for the computer. To perform verification, a series of tests was defined using the actual flight type hardware and simulated flight conditions. Then simulated flights were flown and detailed performance analysis was conducted. The intent of most BFS tests was to demonstrate that a stable flightpath could be obtained after engagement from an anomalous initial condition. The extention of the BFS to meet the requirements of the orbital flight test phase is also described.

Towards inverse modeling of turbidity currents: The inverse lock-exchange problem

NASA Astrophysics Data System (ADS)

Lesshafft, Lutz; Meiburg, Eckart; Kneller, Ben; Marsden, Alison

2011-04-01

A new approach is introduced for turbidite modeling, leveraging the potential of computational fluid dynamics methods to simulate the flow processes that led to turbidite formation. The practical use of numerical flow simulation for the purpose of turbidite modeling so far is hindered by the need to specify parameters and initial flow conditions that are a priori unknown. The present study proposes a method to determine optimal simulation parameters via an automated optimization process. An iterative procedure matches deposit predictions from successive flow simulations against available localized reference data, as in practice may be obtained from well logs, and aims at convergence towards the best-fit scenario. The final result is a prediction of the entire deposit thickness and local grain size distribution. The optimization strategy is based on a derivative-free, surrogate-based technique. Direct numerical simulations are performed to compute the flow dynamics. A proof of concept is successfully conducted for the simple test case of a two-dimensional lock-exchange turbidity current. The optimization approach is demonstrated to accurately retrieve the initial conditions used in a reference calculation.

Blast from pressurized carbon dioxide released into a vented atmospheric chamber

NASA Astrophysics Data System (ADS)

Hansen, P. M.; Gaathaug, A. V.; Bjerketvedt, D.; Vaagsaether, K.

2018-03-01

This study describes the blast from pressurized carbon dioxide (CO2) released from a high-pressure reservoir into an openly vented atmospheric chamber. Small-scale experiments with pure vapor and liquid/vapor mixtures were conducted and compared with simulations. A motivation was to investigate the effects of vent size and liquid content on the peak overpressure and impulse response in the atmospheric chamber. The comparison of vapor-phase CO2 test results with simulations showed good agreement. This numerical code described single-phase gas dynamics inside a closed chamber, but did not model any phase transitions. Hence, the simulations described a vapor-only test into an unvented chamber. Nevertheless, the simulations reproduced the incident shock wave, the shock reflections, and the jet release inside the atmospheric chamber. The rapid phase transition did not contribute to the initial shock strength in the current test geometry. The evaporation rate was too low to contribute to the measured peak overpressure that was in the range of 15-20 kPa. The simulation results produced a calculated peak overpressure of 12 kPa. The liquid tests showed a significantly higher impulse compared to tests with pure vapor. Reducing the vent opening from 0.1 to 0.01 m2 resulted in a slightly higher impulse calculated at 100 ms. The influence of the vent area on the calculated impulse was significant in the vapor-phase tests, but not so clear in the liquid/vapor mixture tests.

Utilization of VAS satellite data in the initialization of an oceanic cyclogenesis simulation

NASA Technical Reports Server (NTRS)

Douglas, Sharon G.; Warner, Thomas T.

1987-01-01

A series of experiments was performed to test various methods of incorporating Visible Infrared Spin Scan Radiometer Atmospheric Sounder (VAS)-sounding data into the initial conditions of the Penn State University/National Center for Atmospheric mesoscale model. The VAS data for this ocean-cyclogenesis case consist of 110 irregularly distributed temperature and humidity soundings located over the North Pacific Ocean and apply at approximately 1200 GMT November 10, 1981. Various methods of utilizing VAS data in the initial condition of a mesoscale model were evaluated.

Utilization of VAS satellite data in the initialization of an oceanic-cyclogenesis simulation

NASA Technical Reports Server (NTRS)

Douglas, Sharon G.; Warner, Thomas T.

1986-01-01

A series of experiments was performed to test various method of incorporating Visible Infrared Spin Scan Radiometer Atmospheric Sounder (VAS)-sounding data into the initial conditions of the Penn State University/National Center for Atmospheric mesoscale model. The VAS data for this ocean-cyclogenesis case consist of 110 irregularly distributed temperature and humidity soundings located over the North Pacific Ocean and apply at approximately 1200 GMT 10 November 1981. Various methods of utilizing VAS data in the initial condition of a mesoscale model were evaluated.

Filter Media Tests Under Simulated Martian Atmospheric Conditions

NASA Technical Reports Server (NTRS)

Agui, Juan H.

2016-01-01

Human exploration of Mars will require the optimal utilization of planetary resources. One of its abundant resources is the Martian atmosphere that can be harvested through filtration and chemical processes that purify and separate it into its gaseous and elemental constituents. Effective filtration needs to be part of the suite of resource utilization technologies. A unique testing platform is being used which provides the relevant operational and instrumental capabilities to test articles under the proper simulated Martian conditions. A series of tests were conducted to assess the performance of filter media. Light sheet imaging of the particle flow provided a means of detecting and quantifying particle concentrations to determine capturing efficiencies. The media's efficiency was also evaluated by gravimetric means through a by-layer filter media configuration. These tests will help to establish techniques and methods for measuring capturing efficiency and arrestance of conventional fibrous filter media. This paper will describe initial test results on different filter media.

EO/IR scene generation open source initiative for real-time hardware-in-the-loop and all-digital simulation

NASA Astrophysics Data System (ADS)

Morris, Joseph W.; Lowry, Mac; Boren, Brett; Towers, James B.; Trimble, Darian E.; Bunfield, Dennis H.

2011-06-01

The US Army Aviation and Missile Research, Development and Engineering Center (AMRDEC) and the Redstone Test Center (RTC) has formed the Scene Generation Development Center (SGDC) to support the Department of Defense (DoD) open source EO/IR Scene Generation initiative for real-time hardware-in-the-loop and all-digital simulation. Various branches of the DoD have invested significant resources in the development of advanced scene and target signature generation codes. The SGDC goal is to maintain unlimited government rights and controlled access to government open source scene generation and signature codes. In addition, the SGDC provides development support to a multi-service community of test and evaluation (T&E) users, developers, and integrators in a collaborative environment. The SGDC has leveraged the DoD Defense Information Systems Agency (DISA) ProjectForge (https://Project.Forge.mil) which provides a collaborative development and distribution environment for the DoD community. The SGDC will develop and maintain several codes for tactical and strategic simulation, such as the Joint Signature Image Generator (JSIG), the Multi-spectral Advanced Volumetric Real-time Imaging Compositor (MAVRIC), and Office of the Secretary of Defense (OSD) Test and Evaluation Science and Technology (T&E/S&T) thermal modeling and atmospherics packages, such as EOView, CHARM, and STAR. Other utility packages included are the ContinuumCore for real-time messaging and data management and IGStudio for run-time visualization and scenario generation.

Space telescope neutral buoyancy simulations: The first two years

NASA Technical Reports Server (NTRS)

Sanders, F. G.

1982-01-01

Neutral Buoyancy simulations which were conducted to validate the crew systems interface as it relates to space telescope on-orbit maintenance and contingency operations is discussed. The initial concept validation tests using low fidelity mockups is described. The entire spectrum of proposed space telescope refurbishment and selected contingencies using upgraded mockups which reflect flight hardware are reported. Findings which may be applicable to future efforts of a similar nature are presented.

Optimization of High-Dimensional Functions through Hypercube Evaluation

PubMed Central

Abiyev, Rahib H.; Tunay, Mustafa

2015-01-01

A novel learning algorithm for solving global numerical optimization problems is proposed. The proposed learning algorithm is intense stochastic search method which is based on evaluation and optimization of a hypercube and is called the hypercube optimization (HO) algorithm. The HO algorithm comprises the initialization and evaluation process, displacement-shrink process, and searching space process. The initialization and evaluation process initializes initial solution and evaluates the solutions in given hypercube. The displacement-shrink process determines displacement and evaluates objective functions using new points, and the search area process determines next hypercube using certain rules and evaluates the new solutions. The algorithms for these processes have been designed and presented in the paper. The designed HO algorithm is tested on specific benchmark functions. The simulations of HO algorithm have been performed for optimization of functions of 1000-, 5000-, or even 10000 dimensions. The comparative simulation results with other approaches demonstrate that the proposed algorithm is a potential candidate for optimization of both low and high dimensional functions. PMID:26339237

Occulting focal plane masks for Terrestrial Planet Finder Coronagraph: design, fabrication, simulations and test results

NASA Technical Reports Server (NTRS)

Balasubramanian, Kunjithapatham; Hoppe, Daniel J.; Halverson, Peter G.; Wilson, Daniel W.; Echternach, Pierre M.; Shi, Fang; Lowman, Andrew E.; Niessner, Albert F.; Trauger, John T.; Shaklan, Stuart B.

2005-01-01

Occulting focal plane masks for the Terrestrial Planet Finder Coronagraph (TPF-C) could be designed with continuous gray scale profile of the occulting pattern such as 1-sinc2 on a suitable material or with micron-scale binary transparent and opaque structures of metallic pattern on glass. We have designed, fabricated and tested both kinds of masks. The fundamental characteristics of such masks and initial test results from the High Contrast Imaging Test bed (HCIT) at JPL are presented.

Performance characteristics of an electric vehicle lead-acid battery pack at elevated temperatures

NASA Technical Reports Server (NTRS)

Chapman, P.

1982-01-01

Discharge testing data electric car battery pack over initial electrolyte temperature variations between 27 and 55 C are presented. The tests were conducted under laboratory conditions and then compared to detailed electric vehicle simulation models. Battery discharge capacity increased with temperature for constant current discharges, and battery energy capacity increased with temperature for constant power discharges. Dynamometer tests of the electric test vehicle showed an increase in range of 25% for the higher electrolyte temperature.

Pretest Plan for a Quarter Scale AFT Segment of the SRB Filament Wound Case in the NSWC Hydroballistics Facility. [space shuttle boosters

NASA Technical Reports Server (NTRS)

Adoue, J. A.

1984-01-01

In support of preflight design loads definition, preliminary water impact scale model are being conducted of space shuttle rocket boosters. The model to be used as well as the instrumentation, test facilities, and test procedures are described for water impact tests being conducted at test conditions to simulate full-scale initial impact at vertical velocities from 65 to 85 ft/sec. zero horizontal velocity, and angles of 0,5, and 10 degrees.

Effect of micro-topography and undrained shear strength on soil erosion

NASA Astrophysics Data System (ADS)

Todisco, Francesca; Vergni, Lorenzo; Vinci, Alessandra; Torri, Dino

2017-04-01

An experiment to evaluate the effect of the pre-event soil surface conditions on the dynamics of the interrill erosion process was performed at the Masse experimental station (Italy) in a replicated 1mx1m plot, located in a 16% slope in a silt-clay-loam soil equipped with a nozzle-type rainfall simulator. Two experiments was performed, each experiment started from a just ploughed bare surface and included 3 simulations (I, II and III in the first experiment and IV, V and VI in the second experiment) carried out in the range of few days. A 30 min pre-wetting phase ensures almost constant initial soil moisture (mean=31%, CV=5%) and bulk density (mean=1.3 g/cm3, CV=3%). Rainfall intensity was maintained constant (mean=67mm/h, CV=2.7%). The independent variables were the initial soil surface conditions that, progressively modified by the rainfall runoff process, were different for the three subsequent simulations. The soil surface initial and final micro-topography and undrained shear strength, T, were monitored through photogrammetric surveys (with I-Phone 6plus) and Torvane test (with pocket-torvane, obliged shear surface at 0.5 cm from soil surface, plate diameter 5 cm, 0.2186 full scale complete revolution 360°, test done on saturated soil surface, with water standing at the surface). Runoff, Q, runoff coefficient, Qr, soil loss, SL and sediment concentration, C, were measured every 5 min. The particle size distribution were also determined. During the simulations Q increases monotonically with typically concave trend. Almost similar consideration can be made for the other variables. A higher frequency of the roughness, RR, (i.e. vertical distance between the surface and a reference horizontal plane, obtained by removing the slope effect) lower than a fixed amount, was measured at the final than the initial step of each simulation and within the single experiment between successive simulations. Therefore, the roughness decreases along with the Q, SL and C increase. In general in the simulations equidistant from the plowing (I-IV, II-V, III-VI) the dynamic of Q, SL and C relative to the second experiment are slightly above that of the first experiment. Actually it is observed that although the frequency distributions of the initial RR of the first simulation of each experiment (I and IV) almost overlap, a higher frequency of the RR lower than a fixed amount was measured in the second experiment (the RR-V >RR-II and the RR-VI>RR-III). Higher T values were often measured at the final than the initial step of each simulation due to sealing and crusting processes associated with the surface smoothness. These and other results open interesting scenarios in the study of the dynamics of the erosion process with particular reference to the relationship between the characteristics of the soil surface and the climatic and hydrological forcing both at event and intra-event time scale. In addition, some results offer discussion points relative to the dynamics of the soil erodibility, showing that the concentration behavior cannot be fully explained by the runoff dynamics.

Visuospatial and psychomotor aptitude predicts endovascular performance of inexperienced individuals on a virtual reality simulator.

PubMed

Van Herzeele, Isabelle; O'Donoghue, Kevin G L; Aggarwal, Rajesh; Vermassen, Frank; Darzi, Ara; Cheshire, Nicholas J W

2010-04-01

This study evaluated virtual reality (VR) simulation for endovascular training of medical students to determine whether innate perceptual, visuospatial, and psychomotor aptitude (VSA) can predict initial and plateau phase of technical endovascular skills acquisition. Twenty medical students received didactic and endovascular training on a commercially available VR simulator. Each student treated a series of 10 identical noncomplex renal artery stenoses endovascularly. The simulator recorded performance data instantly and objectively. An experienced interventionalist rated the performance at the initial and final sessions using generic (out of 40) and procedure-specific (out of 30) rating scales. VSA were tested with fine motor dexterity (FMD, Perdue Pegboard), psychomotor ability (minimally invasive virtual reality surgical trainer [MIST-VR]), image recall (Rey-Osterrieth), and organizational aptitude (map-planning). VSA performance scores were correlated with the assessment parameters of endovascular skills at commencement and completion of training. Medical students exhibited statistically significant learning curves from the initial to the plateau performance for contrast usage (medians, 28 vs 17 mL, P < .001), total procedure time (2120 vs 867 seconds, P < .001), and fluoroscopy time (993 vs. 507 seconds, P < .001). Scores on generic and procedure-specific rating scales improved significantly (10 vs 25, P < .001; 8 vs 17 P < .001). Significant correlations were noted for FMD with initial and plateau sessions for fluoroscopy time (r(s) = -0.564, P = .010; r(s) = -.449, P = .047). FMD correlated with procedure-specific scores at the initial session (r(s) = .607, P = .006). Image recall correlated with generic skills at the end of training (r(s) = .587, P = .006). Simulator-based training in endovascular skills improved performance in medical students. There were significant correlations between initial endovascular skill and fine motor dexterity as well as with image recall at end of the training period. In addition to current recruitment strategies, VSA may be a useful tool for predictive validity studies.

Intermanual transfer in training with an upper-limb myoelectric prosthesis simulator: a mechanistic, randomized, pretest-posttest study.

PubMed

Romkema, Sietske; Bongers, Raoul M; van der Sluis, Corry K

2013-01-01

Intermanual transfer may improve prosthetic handling and acceptance if used in training soon after an amputation. The purpose of this study was to determine whether intermanual transfer effects can be detected after training with a myoelectric upper-limb prosthesis simulator. A mechanistic, randomized, pretest-posttest design was used. A total of 48 right-handed participants (25 women, 23 men) who were able-bodied were randomly assigned to an experimental group or a control group. The experimental group performed a training program of 5 days' duration using the prosthesis simulator. To determine the improvement in skill, a test was administered before, immediately after, and 6 days after training. The control group only performed the tests. Training was performed with the unaffected arm, and tests were performed with the affected arm (the affected arm simulating an amputated limb). Half of the participants were tested with the dominant arm and half with the nondominant arm. Initiation time was defined as the time from starting signal until start of the movement, movement time was defined as the time from the beginning of the movement until completion of the task, and force control was defined as the maximal applied force on a deformable object. The movement time decreased significantly more in the experimental group (F₂,₉₂=7.42, P=.001, η²(G)=.028) when compared with the control group. This finding is indicative of faster handling of the prosthesis. No statistically significant differences were found between groups with regard to initiation time and force control. We did not find a difference in intermanual transfer between the dominant and nondominant arms. The training utilized participants who were able-bodied in a laboratory setting and focused only on transradial amputations. Intermanual transfer was present in the affected arm after training the unaffected arm with a myoelectric prosthesis simulator, and this effect did not depend on laterality. This effect may improve rehabilitation of patients with an upper-limb amputation.

Advancements in Chinese Geomagnetism and Aeronomy during the Last Thirty Years,

DTIC Science & Technology

1981-02-09

movements of charged particles in geomagnetic fields and neutral line magnetic fields and they vigorously initiated simulated tests. References (120-121... telluric prospecting and related probems; (6) Magnetic prospecting and interpretation of data; (7) Some research on geomagnetic instruments; (8

Development and mechanical properties of structural materials from lunar simulants

NASA Technical Reports Server (NTRS)

Desai, Chandra S.; Girdner, K.; Saadatmanesh, H.; Allen, T.

1991-01-01

Development of the technologies for manufacture of structural and construction materials on the Moon, utilizing local lunar soil (regolith), without the use of water, is an important element for habitats and explorations in space. Here, it is vital that the mechanical behavior such as strength and flexural properties, fracture toughness, ductility and deformation characteristics be defined toward establishment of the ranges of engineering applications of the materials developed. The objective is to describe the research results in two areas for the above goal: (1) liquefaction of lunar simulant (at about 100 C) with different additives (fibers, powders, etc.); and (2) development and use of a new triaxial test device in which lunar simulants are first compressed under cycles of loading, and then tested with different vacuums and initial confining or in situ stress.

Mixing Enhancement by Tabs in Round Supersonic Jets

NASA Technical Reports Server (NTRS)

Seiner, John M.; Grosch, C. E.

1998-01-01

The objective of this study was to analyze jet plume mass flow entrainment rates associated with the introduction of counter-rotating streamwise vorticity by prism shaped devices (tabs) located at the lip of the nozzle. We have examined the resulting mixing process through coordinated experimental tests and numerical simulations of the supersonic flow from a model axisymmetric nozzle. In the numerical simulations, the total induced vorticity was held constant while varying the distribution of counter-rotating vorticity around the nozzle lip training edge. In the experiment, the number of tabs applied was varied while holding the total projected area constant. Evaluations were also conducted on initial vortex strength. The results of this work show that the initial growth rate of the jet shear layer is increasingly enhanced as more tabs are added, but that the lowest tab count results in the largest entrained mass flow. The numerical simulations confirm these results.

A model of cardiopulmonary bypass staged training integrating technical and non-technical skills dedicated to cardiac trainees.

PubMed

Fouilloux, V; Doguet, F; Kotsakis, A; Dubrowski, A; Berdah, S

2015-03-01

To develop a standardized simulation-based curriculum to teach medical knowledge and technical, communication and critical thinking skills necessary to initiate and wean from cardiopulmonary bypass (CPB) to junior cardiac trainees (CTs) in France. Performance on post-curricular tests was compared between CTs who participated in the new curriculum to those who did not. The simulation-based curriculum was developed by content and education experts. Simulations sequentially taught the skills necessary for initiating and weaning from CPB as well as managing crises by adding fidelity and complexity to scenarios. Nine CTs were randomly assigned to the new curriculum (n=5) or the traditional curriculum (n=4). Skills were assessed using tests of medical knowledge and technical, communication (GRS) and critical thinking (SCT) skills. A two-sample Wilcoxon rank-sum test compared average scores between the two groups. Alpha of 0.05 was set to indicate statistically significant differences. The resutls revealed that CTs in the new curriculum significantly outperformed CTs in the traditional curriculum on technical (18.2 vs 14.8, p=0.05) and communication (3.5 vs 2.2, p=0.013) skills. There was no significant difference between CTs in the new curriculum in the Script Concordance Test (16.5 vs 14.8, p=0.141) and knowledge tests (26.9 vs 24.6, p=0.14) compared to CTs in the traditional curriculum. Our new curriculum teaches communication and technical skills necessary for CPB. The results of this pilot study are encouraging and relevant. They give grounds for future research with a larger panel of trainees. Based on the current distribution of scores, a sample size of 12 CTs per group should yield significant results for all tests. © The Author(s) 2014.

A Discrete Event Simulation Model to Assess the Economic Value of a Hypothetical Pharmacogenomics Test for Statin-Induced Myopathy in Patients Initiating a Statin in Secondary Cardiovascular Prevention.

PubMed

Mitchell, Dominic; Guertin, Jason R; Dubois, Anick; Dubé, Marie-Pierre; Tardif, Jean-Claude; Iliza, Ange Christelle; Fanton-Aita, Fiorella; Matteau, Alexis; LeLorier, Jacques

2018-04-01

Statin (HMG-CoA reductase inhibitor) therapy is the mainstay dyslipidemia treatment and reduces the risk of a cardiovascular (CV) event (CVE) by up to 35%. However, adherence to statin therapy is poor. One reason patients discontinue statin therapy is musculoskeletal pain and the associated risk of rhabdomyolysis. Research is ongoing to develop a pharmacogenomics (PGx) test for statin-induced myopathy as an alternative to the current diagnosis method, which relies on creatine kinase levels. The potential economic value of a PGx test for statin-induced myopathy is unknown. We developed a lifetime discrete event simulation (DES) model for patients 65 years of age initiating a statin after a first CVE consisting of either an acute myocardial infarction (AMI) or a stroke. The model evaluates the potential economic value of a hypothetical PGx test for diagnosing statin-induced myopathy. We have assessed the model over the spectrum of test sensitivity and specificity parameters. Our model showed that a strategy with a perfect PGx test had an incremental cost-utility ratio of 4273 Canadian dollars ($Can) per quality-adjusted life year (QALY). The probabilistic sensitivity analysis shows that when the payer willingness-to-pay per QALY reaches $Can12,000, the PGx strategy is favored in 90% of the model simulations. We found that a strategy favoring patients staying on statin therapy is cost effective even if patients maintained on statin are at risk of rhabdomyolysis. Our results are explained by the fact that statins are highly effective in reducing the CV risk in patients at high CV risk, and this benefit largely outweighs the risk of rhabdomyolysis.

Numerical investigation for formability of aluminum 6016 alloy under non-isothermal warm forming process

NASA Astrophysics Data System (ADS)

Hu, P.; Dai, M. H.; Ying, L.; Shi, D. Y.; Zhao, K. M.; Lu, J. D.

2013-05-01

The warm forming technology of aluminum alloy has attracted attention from worldwide automotive engineering sector in recent years, with which the complex geometry parts can be realized at elevated temperature. A non-isothermal warm forming process for the heat treatable aluminum can quickly carry out its application on traditional production line by adding a furnace to heat up the aluminum alloy sheet. The 6000 aluminum alloy was investigated by numerical simulation and experiment using the Nakajima test model in this paper. A modified Fields-Backofen model was introduced into numerical simulation process to describe the thermo-mechanical flow behavior of a 6000 series aluminum alloy. The experimental data was obtained by conducting thermal-mechanical uniaxial tensile experiment in temperatures range of 25˜400°C to guarantee the numerical simulation more accurate. The numerical simulation was implemented with LS_DYNA software in terms of coupled dynamic explicit method for investigating the effect of initial forming temperature and the Binder Holder Force (BHF), which are critical process parameters in non-isothermal warm forming. The results showed that the optimal initial forming temperature range was 300°C˜350°C. By means of conducting numerical simulation in deep drawing box model, the forming window of BHF and temperature around the optimal initial forming temperature (275°, 300° and 325°) are investigated, which can provide guidance to actual experiment.

The value of confirmatory testing in early infant HIV diagnosis programmes in South Africa: A cost-effectiveness analysis.

PubMed

Dunning, Lorna; Francke, Jordan A; Mallampati, Divya; MacLean, Rachel L; Penazzato, Martina; Hou, Taige; Myer, Landon; Abrams, Elaine J; Walensky, Rochelle P; Leroy, Valériane; Freedberg, Kenneth A; Ciaranello, Andrea

2017-11-01

The specificity of nucleic acid amplification tests (NAATs) used for early infant diagnosis (EID) of HIV infection is <100%, leading some HIV-uninfected infants to be incorrectly identified as HIV-infected. The World Health Organization recommends that infants undergo a second NAAT to confirm any positive test result, but implementation is limited. Our objective was to determine the impact and cost-effectiveness of confirmatory HIV testing for EID programmes in South Africa. Using the Cost-effectiveness of Preventing AIDS Complications (CEPAC)-Pediatric model, we simulated EID testing at age 6 weeks for HIV-exposed infants without and with confirmatory testing. We assumed a NAAT cost of US$25, NAAT specificity of 99.6%, NAAT sensitivity of 100% for infants infected in pregnancy or at least 4 weeks prior to testing, and a mother-to-child transmission (MTCT) rate at 12 months of 4.9%; we simulated guideline-concordant rates of testing uptake, result return, and antiretroviral therapy (ART) initiation (100%). After diagnosis, infants were linked to and retained in care for 10 years (false-positive) or lifelong (true-positive). All parameters were varied widely in sensitivity analyses. Outcomes included number of infants with false-positive diagnoses linked to ART per 1,000 ART initiations, life expectancy (LE, in years) and per-person lifetime HIV-related healthcare costs. Both without and with confirmatory testing, LE was 26.2 years for HIV-infected infants and 61.4 years for all HIV-exposed infants; clinical outcomes for truly infected infants did not differ by strategy. Without confirmatory testing, 128/1,000 ART initiations were false-positive diagnoses; with confirmatory testing, 1/1,000 ART initiations were false-positive diagnoses. Because confirmatory testing averted costly HIV care and ART in truly HIV-uninfected infants, it was cost-saving: total cost US$1,790/infant tested, compared to US$1,830/infant tested without confirmatory testing. Confirmatory testing remained cost-saving unless NAAT cost exceeded US$400 or the HIV-uninfected status of infants incorrectly identified as infected was ascertained and ART stopped within 3 months of starting. Limitations include uncertainty in the data used in the model, which we examined with sensitivity and uncertainty analyses. We also excluded clinical harms to HIV-uninfected infants incorrectly treated with ART after false-positive diagnosis (e.g., medication toxicities); including these outcomes would further increase the value of confirmatory testing. Without confirmatory testing, in settings with MTCT rates similar to that of South Africa, more than 10% of infants who initiate ART may reflect false-positive diagnoses. Confirmatory testing prevents inappropriate HIV diagnosis, is cost-saving, and should be adopted in all EID programmes.

The real and apparent convergence of N-body simulations of the dark matter structures: Is the Navarro-Frenk-White profile real?

NASA Astrophysics Data System (ADS)

Baushev, A. N.

2015-03-01

While N-body simulations suggest a cuspy profile in the centra of the dark matter halos of galaxies, the majority of astronomical observations favor a relatively soft cored density distribution of these regions. The routine method of testing the convergence of N-body simulations (in particular, the negligibility of two-body scattering effect) is to find the conditions under which formed structures is insensitive to numerical parameters. The results obtained with this approach suggest a surprisingly minor role of the particle collisions: the central density profile remains untouched and close to the Navarro-Frenk-White shape, even if the simulation time significantly exceeds the collisional relaxation time τr . In order to check the influence of the unphysical test body collisions we use the Fokker-Planck equation. It turns out that a profile ρ ∝r-β where β ≃ 1 is an attractor: the Fokker-Planck diffusion transforms any reasonable initial distribution into it in a time shorter than τr , and then the cuspy profile should survive much longer than τr , since the Fokker-Planck diffusion is self-compensated if β ≃ 1 . Thus the purely numerical effect of test body scattering may create a stable NFW-like pseudosolution. Moreover, its stability may be mistaken for the simulation convergence. We present analytical estimations for this potential bias effect and call for numerical tests. For that purpose, we suggest a simple test that can be performed as the simulation progresses and would indicate the magnitude of the collisional influence and the veracity of the simulation results.

Combining high performance simulation, data acquisition, and graphics display computers

NASA Technical Reports Server (NTRS)

Hickman, Robert J.

1989-01-01

Issues involved in the continuing development of an advanced simulation complex are discussed. This approach provides the capability to perform the majority of tests on advanced systems, non-destructively. The controlled test environments can be replicated to examine the response of the systems under test to alternative treatments of the system control design, or test the function and qualification of specific hardware. Field tests verify that the elements simulated in the laboratories are sufficient. The digital computer is hosted by a Digital Equipment Corp. MicroVAX computer with an Aptec Computer Systems Model 24 I/O computer performing the communication function. An Applied Dynamics International AD100 performs the high speed simulation computing and an Evans and Sutherland PS350 performs on-line graphics display. A Scientific Computer Systems SCS40 acts as a high performance FORTRAN program processor to support the complex, by generating numerous large files from programs coded in FORTRAN that are required for the real time processing. Four programming languages are involved in the process, FORTRAN, ADSIM, ADRIO, and STAPLE. FORTRAN is employed on the MicroVAX host to initialize and terminate the simulation runs on the system. The generation of the data files on the SCS40 also is performed with FORTRAN programs. ADSIM and ADIRO are used to program the processing elements of the AD100 and its IOCP processor. STAPLE is used to program the Aptec DIP and DIA processors.

PSL Icing Facility Upgrade Overview

NASA Technical Reports Server (NTRS)

Griffin, Thomas A.; Dicki, Dennis J.; Lizanich, Paul J.

2014-01-01

The NASA Glenn Research Center Propulsion Systems Lab (PSL) was recently upgraded to perform engine inlet ice crystal testing in an altitude environment. The system installed 10 spray bars in the inlet plenum for ice crystal generation using 222 spray nozzles. As an altitude test chamber, the PSL is capable of simulating icing events at altitude in a groundtest facility. The system was designed to operate at altitudes from 4,000 to 40,000 ft at Mach numbers up to 0.8M and inlet total temperatures from -60 to +15 degF. This paper and presentation will be part of a series of presentations on PSL Icing and will cover the development of the icing capability through design, developmental testing, installation, initial calibration, and validation engine testing. Information will be presented on the design criteria and process, spray bar developmental testing at Cox and Co., system capabilities, and initial calibration and engine validation test. The PSL icing system was designed to provide NASA and the icing community with a facility that could be used for research studies of engine icing by duplicating in-flight events in a controlled ground-test facility. With the system and the altitude chamber we can produce flight conditions and cloud environments to simulate those encountered in flight. The icing system can be controlled to set various cloud uniformities, droplet median volumetric diameter (MVD), and icing water content (IWC) through a wide variety of conditions. The PSL chamber can set altitudes, Mach numbers, and temperatures of interest to the icing community and also has the instrumentation capability of measuring engine performance during icing testing. PSL last year completed the calibration and initial engine validation of the facility utilizing a Honeywell ALF502-R5 engine and has duplicated in-flight roll back conditions experienced during flight testing. This paper will summarize the modifications and buildup of the facility to accomplish these tests.

The effect of 'running-in' on the tribology and surface morphology of metal-on-metal Birmingham hip resurfacing device in simulator studies.

PubMed

Vassiliou, K; Elfick, A P D; Scholes, S C; Unsworth, A

2006-02-01

It is well documented that hard bearing combinations show a running-in phenomenon in vitro and there is also some evidence of this from retrieval studies. In order to investigate this phenomenon, five Birmingham hip resurfacing devices were tested in a hip wear simulator. One of these (joint 1) was also tested in a friction simulator before, during, and after the wear test and surface analysis was conducted throughout portions of the testing. The wear showed the classical running in with the wear rate falling from 1.84 mm3 per 10(6) cycles for the first 10(6) cycles of testing to 0.24 mm3 per 10(6) cycles over the final 2 x 10(6) cycles of testing. The friction tests suggested boundary lubrication initially, but at 1 x 10(6) cycles a mixed lubrication regime was evident. By 2 x 10(6) cycles the classical Stribeck curve had formed, indicating a considerable contribution from the fluid film at higher viscosities. This continued to be evident at both 3 x 10(6) and 5 x 10(6) cycles. The surface study complements these findings.

Early Results from Solar Dynamic Space Power System Testing

NASA Technical Reports Server (NTRS)

Shaltens, Richard K.; Mason, Lee S.

1996-01-01

A government/industry team designed, built and tested a 2-kWe solar dynamic space power system in a large thermal vacuum facility with a simulated Sun at the NASA Lewis Research Center. The Lewis facility provides an accurate simulation of temperatures, high vacuum and solar flux as encountered in low-Earth orbit. The solar dynamic system includes a Brayton power conversion unit integrated with a solar receiver which is designed to store energy for continuous power operation during the eclipse phase of the orbit. This paper reviews the goals and status of the Solar Dynamic Ground Test Demonstration project and describes the initial testing, including both operational and performance data. System testing to date has accumulated over 365 hours of power operation (ranging from 400 watts to 2.0-W(sub e)), including 187 simulated orbits, 16 ambient starts and 2 hot restarts. Data are shown for an orbital startup, transient and steady-state orbital operation and shutdown. System testing with varying insolation levels and operating speeds is discussed. The solar dynamic ground test demonstration is providing the experience and confidence toward a successful flight demonstration of the solar dynamic technologies on the Space Station Mir in 1997.

6DOF Testing of the SLS Inertial Navigation Unit

NASA Technical Reports Server (NTRS)

Geohagan, Kevin; Bernard, Bill; Oliver, T. Emerson; Leggett, Jared; Strickland, Dennis

2018-01-01

The Navigation System on the NASA Space Launch System (SLS) Block 1 vehicle performs initial alignment of the Inertial Navigation System (INS) navigation frame through gyrocompass alignment (GCA). Because the navigation architecture for the SLS Block 1 vehicle is a purely inertial system, the accuracy of the achieved orbit relative to mission requirements is very sensitive to initial alignment accuracy. The assessment of this sensitivity and many others via simulation is a part of the SLS Model-Based Design and Model-Based Requirements approach. As a part of the aforementioned, 6DOF Monte Carlo simulation is used in large part to develop and demonstrate verification of program requirements. To facilitate this and the GN&C flight software design process, an SLS-Program-controlled Design Math Model (DMM) of the SLS INS was developed by the SLS Navigation Team. The SLS INS model implements all of the key functions of the hardware-namely, GCA, inertial navigation, and FDIR (Fault Detection, Isolation, and Recovery)-in support of SLS GN&C design requirements verification. Despite the strong sensitivity to initial alignment, GCA accuracy requirements were not verified by test due to program cost and schedule constraints. Instead, the system relies upon assessments performed using the SLS INS model. In order to verify SLS program requirements by analysis, the SLS INS model is verified and validated against flight hardware. In lieu of direct testing of GCA accuracy in support of requirement verification, the SLS Navigation Team proposed and conducted an engineering test to, among other things, validate the GCA performance and overall behavior of the SLS INS model through comparison with test data. This paper will detail dynamic hardware testing of the SLS INS, conducted by the SLS Navigation Team at Marshall Space Flight Center's 6DOF Table Facility, in support of GCA performance characterization and INS model validation. A 6-DOF motion platform was used to produce 6DOF pad twist and sway dynamics while a simulated SLS flight computer communicated with the INS. Tests conducted include an evaluation of GCA algorithm robustness to increasingly dynamic pad environments, an examination of GCA algorithm stability and accuracy over long durations, and a long-duration static test to gather enough data for Allan Variance analysis. Test setup, execution, and data analysis will be discussed, including analysis performed in support of SLS INS model validation.

Forecasting of dissolved oxygen in the Guanting reservoir using an optimized NGBM (1,1) model.

PubMed

An, Yan; Zou, Zhihong; Zhao, Yanfei

2015-03-01

An optimized nonlinear grey Bernoulli model was proposed by using a particle swarm optimization algorithm to solve the parameter optimization problem. In addition, each item in the first-order accumulated generating sequence was set in turn as an initial condition to determine which alternative would yield the highest forecasting accuracy. To test the forecasting performance, the optimized models with different initial conditions were then used to simulate dissolved oxygen concentrations in the Guanting reservoir inlet and outlet (China). The empirical results show that the optimized model can remarkably improve forecasting accuracy, and the particle swarm optimization technique is a good tool to solve parameter optimization problems. What's more, the optimized model with an initial condition that performs well in in-sample simulation may not do as well as in out-of-sample forecasting. Copyright © 2015. Published by Elsevier B.V.

Velocity bias in the distribution of dark matter halos

NASA Astrophysics Data System (ADS)

Baldauf, Tobias; Desjacques, Vincent; Seljak, Uroš

2015-12-01

The standard formalism for the coevolution of halos and dark matter predicts that any initial halo velocity bias rapidly decays to zero. We argue that, when the purpose is to compute statistics like power spectra etc., the coupling in the momentum conservation equation for the biased tracers must be modified. Our new formulation predicts the constancy in time of any statistical halo velocity bias present in the initial conditions, in agreement with peak theory. We test this prediction by studying the evolution of a conserved halo population in N -body simulations. We establish that the initial simulated halo density and velocity statistics show distinct features of the peak model and, thus, deviate from the simple local Lagrangian bias. We demonstrate, for the first time, that the time evolution of their velocity is in tension with the rapid decay expected in the standard approach.

Effects of spine flexion and erector spinae maximal force on vertical squat jump height: a computational simulation study.

PubMed

Blache, Yoann; Monteil, Karine

2015-03-01

The purpose of this study was to evaluate the single and combined effects of initial spine flexion and maximal isometric force of the erector spinae on maximal vertical jump height during maximal squat jumping. Seven initial flexions of the 'thorax-head-arm' segment (between 20.1° and 71.6°) and five maximal isometric forces of the erector spinae (between 5600 and 8600 N) were tested. Thus, 35 squat jumps were simulated using a 2D simulation model of the musculoskeletal system. Vertical jump height varied at most about 0.094 and 0.021 m when the initial flexion of the 'thorax-head-arm' segment and the maximal force of the erector spinae were, respectively, maximal. These results were explained for the most part by the variation of total muscle work. The latter was mainly influenced by the work produced by the erector spinae which increased at most about 57 and 110 J when the initial flexion of the 'thorax-head-arm' segment and the maximal force of the erector spinae were, respectively, maximal. It was concluded that the increase in the initial flexion of the 'thorax-head-arm' segment and in the maximal isometric force of the erector spinae enables an increase in maximal vertical jump height during maximal squat jumping.

Realistic Testing of the Safe Affordable Fission Engine (SAFE-100) Thermal Simulator Using Fiber Bragg Gratings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stinson-Bagby, Kelly L.; Fielder, Robert S.; Van Dyke, Melissa K.

2004-02-04

The motivation for the reported research was to support NASA space nuclear power initiatives through the development of advanced fiber optic sensors for space-based nuclear power applications. Distributed high temperature measurements were made with 20 FBG temperature sensors installed in the SAFE-100 thermal simulator at the NASA Marshal Space Flight Center. Experiments were performed at temperatures approaching 800 deg. C and 1150 deg. C for characterization studies of the SAFE-100 core. Temperature profiles were successfully generated for the core during temperature increases and decreases. Related tests in the SAFE-100 successfully provided strain measurement data.

Computer Simulation and Modeling of CO2 Removal Systems for Exploration 2013-2014

NASA Technical Reports Server (NTRS)

Coker, R.; Knox, J.; Gomez, C.

2015-01-01

The Atmosphere Revitalization Recovery and Environmental Monitoring (ARREM) project was initiated in September of 2011 as part of the Advanced Exploration Systems (AES) program. Under the ARREM project and the follow-on Life Support Systems (LSS) project, testing of sub-scale and full-scale systems has been combined with multiphysics computer simulations for evaluation and optimization of subsystem approaches. In particular, this paper will describes the testing and 1-D modeling of the combined water desiccant and carbon dioxide sorbent subsystems of the carbon dioxide removal assembly (CDRA). The goal is a full system predictive model of CDRA to guide system optimization and development.

Computer simulation of solder joint failure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burchett, S.N.; Frear, D.R.; Rashid, M.M.

The thermomechanical fatigue failure of solder joints is increasingly becoming an important reliability issue for electronic packages. The purpose of this Laboratory Directed Research and Development (LDRD) project was to develop computational tools for simulating the behavior of solder joints under strain and temperature cycling, taking into account the microstructural heterogeneities that exist in as-solidified near eutectic Sn-Pb joints, as well as subsequent microstructural evolution. The authors present two computational constitutive models, a two-phase model and a single-phase model, that were developed to predict the behavior of near eutectic Sn-Pb solder joints under fatigue conditions. Unique metallurgical tests provide themore » fundamental input for the constitutive relations. The two-phase model mathematically predicts the heterogeneous coarsening behavior of near eutectic Sn-Pb solder. The finite element simulations with this model agree qualitatively with experimental thermomechanical fatigue tests. The simulations show that the presence of an initial heterogeneity in the solder microstructure could significantly degrade the fatigue lifetime. The single-phase model was developed to predict solder joint behavior using materials data for constitutive relation constants that could be determined through straightforward metallurgical experiments. Special thermomechanical fatigue tests were developed to give fundamental materials input to the models, and an in situ SEM thermomechanical fatigue test system was developed to characterize microstructural evolution and the mechanical behavior of solder joints during the test. A shear/torsion test sample was developed to impose strain in two different orientations. Materials constants were derived from these tests. The simulation results from the two-phase model showed good fit to the experimental test results.« less

Clinical utility of RT-PCR in assessing HER 2 gene expression versus traditional IHC and FISH in breast cancer patients.

PubMed

Suryavanshi, Moushumi; Mehta, Anurag; Jaipuria, Jiten; Kumar, Dushyant; Vishwakarma, Gayatri; Panigrahi, Manoj Kumar; Verma, Haristuti; Saifi, Mumtaz; Sharma, Sanjeev; Tandon, Simran; Doval, D C; Das, Bhudev C

2018-02-09

IHC and FISH are used for categorizing HER 2 status in breast cancer at the protein and DNA level, respectively. HER 2 expression at the RNA level is quantitative, cheaper, easier to standardize and free from interobserver variation. 115 consecutive patients were tested by IHC, FISH and RT-PCR (test cohort). Assuming FISH result to be the response variable, ROC curves for RT-PCR ratio were analyzed to label HER 2 negative, equivocal and positive cases as RT-PCR score 1, 2 and 3, respectively. Inter-relationships between RT-PCR, IHC and FISH were defined. 'Clinical benefit' of a test was defined as proportion of patients labeled unequivocally as HER 2 positive or negative. Population for 1 year was simulated constraint to previous reports of HER 2 positivity and IHC category distribution by a meta-analysis of previous studies that evaluated concordance between IHC and FISH to determine HER 2 status (simulation cohort). Four diagnostic pathways in the simulation cohort were defined-(1) initial IHC, followed by FISH (conventional pathway); (2) initial RT-PCR, followed by FISH; (3) initial IHC, followed by RT-PCR and then by FISH; (4) initial RT-PCR, followed by IHC and then by FISH. The clinical benefit of IHC and RT-PCR in the four pathways was analyzed and sensitivity analysis for incremental cost-effectiveness ratio and cost-benefit comapring RT-PCR against IHC, both as first-line tests and among those with IHC score 2 as a reflex second-line test was performed by the Monte Carlo technique. 115 patients comprised the study population. While none with IHC score of 0 or 1 was FISH positive for HER 2, all cases with IHC score of 3 were FISH positive. 43 cases were assigned IHC score of 2. Thus, 72 patients benefited from the initial IHC testing [clinical benefit 62.6%], with the overall concordance between IHC and FISH being 100% for those with IHC score of 0, 1 and 3 (conclusive IHC categories). For RT-PCR with 100% concordance, 15.7% (115-97 = 18) patients would have benefited from RT-PCR testing if it was used as a first-line test. If RT-PCR would have been used as a second-line test among those with IHC score 2 (n = 43), then only 6 patients would have been assigned a conclusive RT-PCR category (category 1 or 3) translating to a clinical benefit of 14% (6/43) as a second-line test. As a second-line test it had 51% probability to prove more cost-effective than the conventional pathway, provided the cost of RT-PCR was 0.4 times the cost of IHC. Also in a three-step pathway, RT-PCR upfront would have 56% probability of higher cost-benefit provided the cost of RT-PCR was 0.1 times the cost of IHC. RT-PCR results were found to be suboptimal to IHC in terms of discriminative ability and clinical benefit; thus, it is unlikely to replace IHC as a first-line test in the near future.

Mapping Nuclear Fallout Using the Weather Research & Forecasting (WRF) Model

DTIC Science & Technology

2012-09-01

relevant modules, originally designed to predict the settling of volcanic ash, such that a stabilized cloud of nuclear particulate is initialized...within the model. This modified code is then executed for various atmospheric test explosions and the results are qualitatively and quantitatively...HYSPLIT Simulation ....................................... 44  Figure 7. WRF Fallout Prediction for Test Shot George, 0.8 R/h at H+1

Experimental setup for investigation of two-phase (water-air) flows in a tube

NASA Astrophysics Data System (ADS)

Kazunin, D. V.; Lashkov, V. A.; Mashek, I. Ch.; Khoronzhuk, R. S.

2018-05-01

A special setup was designed and built at St. Petersburg State University for providing experimental research in flow dynamics of the of air-water mixtures in a pipeline. The test section of the setup allows simulating a wide range of flow regimes of a gas-liquid mixture. The parameters of the experimental setup are given; the initial test results are discussed.

The Stellar IMF from Isothermal MHD Turbulence

NASA Astrophysics Data System (ADS)

Haugbølle, Troels; Padoan, Paolo; Nordlund, Åke

2018-02-01

We address the turbulent fragmentation scenario for the origin of the stellar initial mass function (IMF), using a large set of numerical simulations of randomly driven supersonic MHD turbulence. The turbulent fragmentation model successfully predicts the main features of the observed stellar IMF assuming an isothermal equation of state without any stellar feedback. As a test of the model, we focus on the case of a magnetized isothermal gas, neglecting stellar feedback, while pursuing a large dynamic range in both space and timescales covering the full spectrum of stellar masses from brown dwarfs to massive stars. Our simulations represent a generic 4 pc region within a typical Galactic molecular cloud, with a mass of 3000 M ⊙ and an rms velocity 10 times the isothermal sound speed and 5 times the average Alfvén velocity, in agreement with observations. We achieve a maximum resolution of 50 au and a maximum duration of star formation of 4.0 Myr, forming up to a thousand sink particles whose mass distribution closely matches the observed stellar IMF. A large set of medium-size simulations is used to test the sink particle algorithm, while larger simulations are used to test the numerical convergence of the IMF and the dependence of the IMF turnover on physical parameters predicted by the turbulent fragmentation model. We find a clear trend toward numerical convergence and strong support for the model predictions, including the initial time evolution of the IMF. We conclude that the physics of isothermal MHD turbulence is sufficient to explain the origin of the IMF.

A Hardware-in-the-Loop Testbed for Spacecraft Formation Flying Applications

NASA Technical Reports Server (NTRS)

Leitner, Jesse; Bauer, Frank H. (Technical Monitor)

2001-01-01

The Formation Flying Test Bed (FFTB) at NASA Goddard Space Flight Center (GSFC) is being developed as a modular, hybrid dynamic simulation facility employed for end-to-end guidance, navigation, and control (GN&C) analysis and design for formation flying clusters and constellations of satellites. The FFTB will support critical hardware and software technology development to enable current and future missions for NASA, other government agencies, and external customers for a wide range of missions, particularly those involving distributed spacecraft operations. The initial capabilities of the FFTB are based upon an integration of high fidelity hardware and software simulation, emulation, and test platforms developed at GSFC in recent years; including a high-fidelity GPS simulator which has been a fundamental component of the Guidance, Navigation, and Control Center's GPS Test Facility. The FFTB will be continuously evolving over the next several years from a too[ with initial capabilities in GPS navigation hardware/software- in-the- loop analysis and closed loop GPS-based orbit control algorithm assessment to one with cross-link communications and relative navigation analysis and simulation capability. Eventually the FFT13 will provide full capability to support all aspects of multi-sensor, absolute and relative position determination and control, in all (attitude and orbit) degrees of freedom, as well as information management for satellite clusters and constellations. In this paper we focus on the architecture for the FFT13 as a general GN&C analysis environment for the spacecraft formation flying community inside and outside of NASA GSFC and we briefly reference some current and future activities which will drive the requirements and development.

Pretest and posttest calculations of Semiscale Test S-07-10D with the TRAC computer program. [PWR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duerre, K.H.; Cort, G.E.; Knight, T.D.

The Transient Reactor Analysis Code (TRAC) developed at the Los Alamos National Laboratory was used to predict the behavior of the small-break experiment designated Semiscale S-07-10D. This test simulates a 10 per cent communicative cold-leg break with delayed Emergency Core Coolant injection and blowdown of the broken-loop steam generator secondary. Both pretest calculations that incorporated measured initial conditions and posttest calculations that incorporated measured initial conditions and measured transient boundary conditions were completed. The posttest calculated parameters were generally between those obtained from pretest calculations and those from the test data. The results are strongly dependent on depressurization rate and,more » hence, on break flow.« less

Mechanical Characterization of the Iter Mock-Up Insulation after Reactor Irradiation

NASA Astrophysics Data System (ADS)

Prokopec, R.; Humer, K.; Fillunger, H.; Maix, R. K.; Weber, H. W.

2010-04-01

The ITER mock-up project was launched in order to demonstrate the feasibility of an industrial impregnation process using the new cyanate ester/epoxy blend. The mock-up simulates the TF winding pack cross section by a stainless steel structure with the same dimensions as the TF winding pack at a length of 1 m. It consists of 7 plates simulating the double pancakes, each of them is wrapped with glass fiber/Kapton sandwich tapes. After stacking the 7 plates, additional insulation layers are wrapped to simulate the ground insulation. This paper presents the results of the mechanical quality tests on the mock-up pancake insulation. Tensile and short beam shear specimens were cut from the plates extracted from the mock-up and tested at 77 K using a servo-hydraulic material testing device. All tests were repeated after reactor irradiation to a fast neutron fluence of 1×1022 m-2 (E>0.1 MeV). In order to simulate the pulsed operation of ITER, tension-tension fatigue measurements were performed in the load controlled mode. Initial results show a high mechanical strength as expected from the high number of thin glass fiber layers, and an excellent homogeneity of the material.

Test Guide for ADS-33E-PRF

DTIC Science & Technology

2008-07-01

8501A (Reference 2), and from the V/STOL specification MIL-F-83300 (Reference 3). ADS-33E-PRF contains intermeshed requirements on not only shoi -t- and...While final verification will in most cases require flight testing, initial checks can be performed through analysis and on ground-based simulators...they are difficult to test, or for some reason are deficient in one or more areas. In such cases one or more alternate criteria are presented where

A Testbed for Evaluating Lunar Habitat Autonomy Architectures

NASA Technical Reports Server (NTRS)

Lawler, Dennis G.

2008-01-01

A lunar outpost will involve a habitat with an integrated set of hardware and software that will maintain a safe environment for human activities. There is a desire for a paradigm shift whereby crew will be the primary mission operators, not ground controllers. There will also be significant periods when the outpost is uncrewed. This will require that significant automation software be resident in the habitat to maintain all system functions and respond to faults. JSC is developing a testbed to allow for early testing and evaluation of different autonomy architectures. This will allow evaluation of different software configurations in order to: 1) understand different operational concepts; 2) assess the impact of failures and perturbations on the system; and 3) mitigate software and hardware integration risks. The testbed will provide an environment in which habitat hardware simulations can interact with autonomous control software. Faults can be injected into the simulations and different mission scenarios can be scripted. The testbed allows for logging, replaying and re-initializing mission scenarios. An initial testbed configuration has been developed by combining an existing life support simulation and an existing simulation of the space station power distribution system. Results from this initial configuration will be presented along with suggested requirements and designs for the incremental development of a more sophisticated lunar habitat testbed.

Calibration and validation of a spar-type floating offshore wind turbine model using the FAST dynamic simulation tool

DOE PAGES

Browning, J. R.; Jonkman, J.; Robertson, A.; ...

2014-12-16

In this study, high-quality computer simulations are required when designing floating wind turbines because of the complex dynamic responses that are inherent with a high number of degrees of freedom and variable metocean conditions. In 2007, the FAST wind turbine simulation tool, developed and maintained by the U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory (NREL), was expanded to include capabilities that are suitable for modeling floating offshore wind turbines. In an effort to validate FAST and other offshore wind energy modeling tools, DOE funded the DeepCwind project that tested three prototype floating wind turbines at 1/50 th scalemore » in a wave basin, including a semisubmersible, a tension-leg platform, and a spar buoy. This paper describes the use of the results of the spar wave basin tests to calibrate and validate the FAST offshore floating simulation tool, and presents some initial results of simulated dynamic responses of the spar to several combinations of wind and sea states. Wave basin tests with the spar attached to a scale model of the NREL 5-megawatt reference wind turbine were performed at the Maritime Research Institute Netherlands under the DeepCwind project. This project included free-decay tests, tests with steady or turbulent wind and still water (both periodic and irregular waves with no wind), and combined wind/wave tests. The resulting data from the 1/50th model was scaled using Froude scaling to full size and used to calibrate and validate a full-size simulated model in FAST. Results of the model calibration and validation include successes, subtleties, and limitations of both wave basin testing and FAST modeling capabilities.« less

A wall interference assessment/correction system

NASA Technical Reports Server (NTRS)

Lo, Ching F.; Ulbrich, N.; Sickles, W. L.; Qian, Cathy X.

1992-01-01

A Wall Signature method, the Hackett method, has been selected to be adapted for the 12-ft Wind Tunnel wall interference assessment/correction (WIAC) system in the present phase. This method uses limited measurements of the static pressure at the wall, in conjunction with the solid wall boundary condition, to determine the strength and distribution of singularities representing the test article. The singularities are used in turn for estimating wall interferences at the model location. The Wall Signature method will be formulated for application to the unique geometry of the 12-ft Tunnel. The development and implementation of a working prototype will be completed, delivered and documented with a software manual. The WIAC code will be validated by conducting numerically simulated experiments rather than actual wind tunnel experiments. The simulations will be used to generate both free-air and confined wind-tunnel flow fields for each of the test articles over a range of test configurations. Specifically, the pressure signature at the test section wall will be computed for the tunnel case to provide the simulated 'measured' data. These data will serve as the input for the WIAC method-Wall Signature method. The performance of the WIAC method then may be evaluated by comparing the corrected parameters with those for the free-air simulation. Each set of wind tunnel/test article numerical simulations provides data to validate the WIAC method. A numerical wind tunnel test simulation is initiated to validate the WIAC methods developed in the project. In the present reported period, the blockage correction has been developed and implemented for a rectangular tunnel as well as the 12-ft Pressure Tunnel. An improved wall interference assessment and correction method for three-dimensional wind tunnel testing is presented in the appendix.

Correction of beam-beam effects in luminosity measurement in the forward region at CLIC

NASA Astrophysics Data System (ADS)

Lukić, S.; Božović-Jelisavčić, I.; Pandurović, M.; Smiljanić, I.

2013-05-01

Procedures for correcting the beam-beam effects in luminosity measurements at CLIC at 3 TeV center-of-mass energy are described and tested using Monte Carlo simulations. The angular counting loss due to the combined Beamstrahlung and initial-state radiation effects is corrected based on the reconstructed velocity of the collision frame of the Bhabha scattering. The distortion of the luminosity spectrum due to the initial-state radiation is corrected by deconvolution. At the end, the counting bias due to the finite calorimeter energy resolution is numerically corrected. To test the procedures, BHLUMI Bhabha event generator, and Guinea-Pig beam-beam simulation were used to generate the outgoing momenta of Bhabha particles in the bunch collisions at CLIC. The systematic effects of the beam-beam interaction on the luminosity measurement are corrected with precision of 1.4 permille in the upper 5% of the energy, and 2.7 permille in the range between 80 and 90% of the nominal center-of-mass energy.

Aircraft Maneuvers for the Evaluation of Flying Qualities and Agility. Volume 1. Maneuver Development Process and Initial Maneuver Set

DTIC Science & Technology

1993-08-01

subtitled "Simulation Data," consists of detailed infonrnation on the design parmneter variations tested, subsequent statistical analyses conducted...used with confidence during the design process. The data quality can be examined in various forms such as statistical analyses of measure of merit data...merit, such as time to capture or nmaximurn pitch rate, can be calculated from the simulation time history data. Statistical techniques are then used

Process-based modelling of NH3 exchange with grazed grasslands

NASA Astrophysics Data System (ADS)

Móring, Andrea; Vieno, Massimo; Doherty, Ruth M.; Milford, Celia; Nemitz, Eiko; Twigg, Marsailidh M.; Horváth, László; Sutton, Mark A.

2017-09-01

In this study the GAG model, a process-based ammonia (NH3) emission model for urine patches, was extended and applied for the field scale. The new model (GAG_field) was tested over two modelling periods, for which micrometeorological NH3 flux data were available. Acknowledging uncertainties in the measurements, the model was able to simulate the main features of the observed fluxes. The temporal evolution of the simulated NH3 exchange flux was found to be dominated by NH3 emission from the urine patches, offset by simultaneous NH3 deposition to areas of the field not affected by urine. The simulations show how NH3 fluxes over a grazed field in a given day can be affected by urine patches deposited several days earlier, linked to the interaction of volatilization processes with soil pH dynamics. Sensitivity analysis showed that GAG_field was more sensitive to soil buffering capacity (β), field capacity (θfc) and permanent wilting point (θpwp) than the patch-scale model. The reason for these different sensitivities is dual. Firstly, the difference originates from the different scales. Secondly, the difference can be explained by the different initial soil pH and physical properties, which determine the maximum volume of urine that can be stored in the NH3 source layer. It was found that in the case of urine patches with a higher initial soil pH and higher initial soil water content, the sensitivity of NH3 exchange to β was stronger. Also, in the case of a higher initial soil water content, NH3 exchange was more sensitive to the changes in θfc and θpwp. The sensitivity analysis showed that the nitrogen content of urine (cN) is associated with high uncertainty in the simulated fluxes. However, model experiments based on cN values randomized from an estimated statistical distribution indicated that this uncertainty is considerably smaller in practice. Finally, GAG_field was tested with a constant soil pH of 7.5. The variation of NH3 fluxes simulated in this way showed a good agreement with those from the simulations with the original approach, accounting for a dynamically changing soil pH. These results suggest a way for model simplification when GAG_field is applied later at regional scale.

A Novel Method to Simulate the Progression of Collagen Degeneration of Cartilage in the Knee: Data from the Osteoarthritis Initiative

PubMed Central

Mononen, Mika E.; Tanska, Petri; Isaksson, Hanna; Korhonen, Rami K.

2016-01-01

We present a novel algorithm combined with computational modeling to simulate the development of knee osteoarthritis. The degeneration algorithm was based on excessive and cumulatively accumulated stresses within knee joint cartilage during physiological gait loading. In the algorithm, the collagen network stiffness of cartilage was reduced iteratively if excessive maximum principal stresses were observed. The developed algorithm was tested and validated against experimental baseline and 4-year follow-up Kellgren-Lawrence grades, indicating different levels of cartilage degeneration at the tibiofemoral contact region. Test groups consisted of normal weight and obese subjects with the same gender and similar age and height without osteoarthritic changes. The algorithm accurately simulated cartilage degeneration as compared to the Kellgren-Lawrence findings in the subject group with excess weight, while the healthy subject group’s joint remained intact. Furthermore, the developed algorithm followed the experimentally found trend of cartilage degeneration in the obese group (R2 = 0.95, p < 0.05; experiments vs. model), in which the rapid degeneration immediately after initiation of osteoarthritis (0–2 years, p < 0.001) was followed by a slow or negligible degeneration (2–4 years, p > 0.05). The proposed algorithm revealed a great potential to objectively simulate the progression of knee osteoarthritis. PMID:26906749

Numerical Analysis of Mixed-Phase Icing Cloud Simulations in the NASA Propulsion Systems Laboratory

NASA Technical Reports Server (NTRS)

Bartkus, Tadas; Tsao, Jen-Ching; Struk, Peter; Van Zante, Judith

2017-01-01

This presentation describes the development of a numerical model that couples the thermal interaction between ice particles, water droplets, and the flowing gas of an icing wind tunnel for simulation of NASA Glenn Research Centers Propulsion Systems Laboratory (PSL). The ultimate goal of the model is to better understand the complex interactions between the test parameters and have greater confidence in the conditions at the test section of the PSL tunnel. The model attempts to explain the observed changes in test conditions by coupling the conservation of mass and energy equations for both the cloud particles and flowing gas mass. Model predictions were compared to measurements taken during May 2015 testing at PSL, where test conditions varied gas temperature, pressure, velocity and humidity levels, as well as the cloud total water content, particle initial temperature, and particle size distribution.

Numerical Analysis of Mixed-Phase Icing Cloud Simulations in the NASA Propulsion Systems Laboratory

NASA Technical Reports Server (NTRS)

Bartkus, Tadas P.; Tsao, Jen-Ching; Struk, Peter M.; Van Zante, Judith F.

2017-01-01

This paper describes the development of a numerical model that couples the thermal interaction between ice particles, water droplets, and the flowing gas of an icing wind tunnel for simulation of NASA Glenn Research Centers Propulsion Systems Laboratory (PSL). The ultimate goal of the model is to better understand the complex interactions between the test parameters and have greater confidence in the conditions at the test section of the PSL tunnel. The model attempts to explain the observed changes in test conditions by coupling the conservation of mass and energy equations for both the cloud particles and flowing gas mass. Model predictions were compared to measurements taken during May 2015 testing at PSL, where test conditions varied gas temperature, pressure, velocity and humidity levels, as well as the cloud total water content, particle initial temperature, and particle size distribution.

Kinetics of thermal and photo-initiated release of tris (1,3-dichloro-2-propyl) phosphate (TDCP) flame retardant from polyurethane foam materials.

PubMed

Ghanem, Raed A

2015-01-01

Kinetics of thermal and photo-initiated release of Tris (1.3-dichloro-2-propyl) phosphate (TDCP) from the polyurethane foam (PUF) materials were studied using a validated chromatographic method with linear calibration curve in the range of 0.03-400 μg mL(-1). Time dependence of TDCP leaching from foam samples was found to follow first-order kinetics; with rate constants directly dependent on ageing temperatures and intensity of UV radiation, rate constants for the thermally and photo initiated were 3.6 × 10(-3), 1.03 × 10(-2), 3.6 × 10(-2) and 3.94 × 10(-2) day(-1), respectively. Migration of TDCP from foam samples simulating skin or oral exposure were observed from all samples regardless of their ageing history, the presence of biological fluids found to enhance the migration rate. Oral exposure to foam material contains TDCP, which was simulated using the Head-over-Heels test, reveals that an average amount of ∼ 1.7% wt./wt. of the total amount of TDCP was found to leach into biological fluids, and it significantly increased to ∼ 6.0% wt./wt. due to ageing conditions. Direct contact between foam material and skin simulated by using the Contact Blotting test reveals that TDCP is transferred from both aged and un-aged samples at different rates, due to the presence of biological fluids; the transferred amount is increased with ageing conditions.

Research Capabilities for Oil-Free Turbomachinery Expanded by New Rotordynamic Simulator Facility

NASA Technical Reports Server (NTRS)

Howard, Samuel A.

2004-01-01

A new test rig has been developed for simulating high-speed turbomachinery shafting using Oil-Free foil air bearing technology. Foil air journal bearings are self-acting hydrodynamic bearings with a flexible inner sleeve surface using air as the lubricant. These bearings have been used in turbomachinery, primarily air cycle machines, for the past four decades to eliminate the need for oil lubrication. More recently, interest has been growing in applying foil bearings to aircraft gas turbine engines. They offer potential improvements in efficiency and power density, decreased maintenance costs, and other secondary benefits. The goal of applying foil air bearings to aircraft gas turbine engines prompted the fabrication of this test rig. The facility enables bearing designers to test potential bearing designs with shafts that simulate the rotating components of a target engine without the high cost of building actual flight hardware. The data collected from this rig can be used to make changes to the shaft and bearings in subsequent design iterations. The rest of this article describes the new test rig and demonstrates some of its capabilities with an initial simulated shaft system. The test rig has two support structures, each housing a foil air journal bearing. The structures are designed to accept any size foil journal bearing smaller than 63 mm (2.5 in.) in diameter. The bearing support structures are mounted to a 91- by 152-cm (3- by 5-ft) table and can be separated by as much as 122 cm (4 ft) and as little as 20 cm (8 in.) to accommodate a wide range of shaft sizes. In the initial configuration, a 9.5-cm (3.75-in.) impulse air turbine drives the test shaft. The impulse turbine, as well as virtually any number of "dummy" compressor and turbine disks, can be mounted on the shaft inboard or outboard of the bearings. This flexibility allows researchers to simulate various engine shaft configurations. The bearing support structures include a unique bearing mounting fixture that rotates to accommodate a laserbased alignment system. This can measure the misalignment of the bearing centers in each of 2 translational degrees of freedom and 2 rotational degrees of freedom. In the initial configuration, with roughly a 30.5-cm- (12-in.-) long shaft, two simulated aerocomponent disks, and two 50.8-cm (2-in.) foil journal bearings, the rig can operate at 65,000 rpm at room temperature. The test facility can measure shaft displacements in both the vertical and horizontal directions at each bearing location. Horizontal and vertical structural vibrations are monitored using accelerometers mounted on the bearing support structures. This information is used to determine system rotordynamic response, including critical speeds, mode shapes, orbit size and shape, and potentially the onset of instabilities. Bearing torque can be monitored as well to predict the power loss in the foil bearings. All of this information is fed back and forth between NASA and the foil bearing designers in an iterative fashion to converge on a final bearing and shaft design for a given engine application. In addition to its application development capabilities, the test rig offers several unique capabilities for basic bearing research. Using the laser alignment system mentioned earlier, the facility will be used to map foil air journal bearing performance. A known misalignment of increasing severity will be induced to determine the sensitivity of foil bearings to misalignment. Other future plans include oil-free integral starter generator testing and development, and dynamic load testing of foil journal bearings.

Dynamics of gas-driven eruptions: Experimental simulations using CO2-H2O-polymer system

NASA Astrophysics Data System (ADS)

Zhang, Youxue; Sturtevant, B.; Stolper, E. M.

1997-02-01

We report exploratory experiments simulating gas-driven eruptions using the CO2-H2O system at room temperature as an analog of natural eruptive systems. The experimental apparatus consists of a test cell and a large tank. Initially, up to 1.0 wt% of CO2 is dissolved in liquid water under a pressure of up to 735 kPa in the test cell. The experiment is initiated by suddenly reducing the pressure of the test cell to a typical tank pressure of 10 kPa. The following are the main results: (1) The style of the process depends on the decompression ratio. There is a threshold decompression ratio above which rapid eruption occurs. (2) During rapid eruption, there is always fragmentation at the liquid-vapor interface. Fragmentation may also occur in the flow interior. (3) Initially, the top of the erupting column ascends at a constant acceleration (instead of constant velocity). (4) Average bubble radius grows as t2/3. (5) When viscosity is 20 times that of pure water or greater, a static foam may be stable after expansion to 97% vesicularity. The experiments provide several insights into natural gas-driven eruptions, including (1) the interplay between bubble growth and ascent of the erupting column must be considered for realistic modeling of bubble growth during gas-driven eruptions, (2) buoyant rise of the bubbly magma is not necessary during an explosive volcanic eruption, and (3) CO2-driven limnic eruptions can be explosive. The violence increases with the initial CO2 content dissolved in water.

Simulation of a tethered microgravity robot pair and validation on a planar air bearing

NASA Astrophysics Data System (ADS)

Mantellato, R.; Lorenzini, E. C.; Sternberg, D.; Roascio, D.; Saenz-Otero, A.; Zachrau, H. J.

2017-09-01

A software model has been developed to simulate the on-orbit dynamics of a dual-mass tethered system where one or both of the tethered spacecraft are able to produce propulsive thrust. The software simulates translations and rotations of both spacecraft, with the visco-elastic tether being simulated as a lumped-mass model. Thanks to this last feature, tether longitudinal and lateral modes of vibration and tether tension can be accurately assessed. Also, the way the spacecraft motion responds to sudden tether tension spikes can be studied in detail. The code enables the simulation of different scenarios, including space tug missions for deorbit maneuvers in a debris mitigation context and general-purpose tethered formation flight missions. This study aims to validate the software through a representative test campaign performed with the MIT Synchronized Position Hold Engage and Reorient Experimental Satellites (SPHERES) planar air bearing system. Results obtained with the numerical simulator are compared with data from direct measurements in different testing setups. The studied cases take into account different initial conditions of the spacecraft velocities and relative attitudes, and thrust forces. Data analysis is presented comparing the results of the simulations with direct measurements of acceleration and Azimuth rate of the two bodies in the planar air bearing test facility using a Nylon tether. Plans for conducting a microgravity test campaign using the SPHERES satellites aboard the International Space Station are also being scheduled in the near future in order to further validate the simulation using data from the relevant operational environment of extended microgravity with full six degree of freedom (per body) motion.

Simulation-based assessment in anesthesiology: requirements for practical implementation.

PubMed

Boulet, John R; Murray, David J

2010-04-01

Simulations have taken a central role in the education and assessment of medical students, residents, and practicing physicians. The introduction of simulation-based assessments in anesthesiology, especially those used to establish various competencies, has demanded fairly rigorous studies concerning the psychometric properties of the scores. Most important, major efforts have been directed at identifying, and addressing, potential threats to the validity of simulation-based assessment scores. As a result, organizations that wish to incorporate simulation-based assessments into their evaluation practices can access information regarding effective test development practices, the selection of appropriate metrics, the minimization of measurement errors, and test score validation processes. The purpose of this article is to provide a broad overview of the use of simulation for measuring physician skills and competencies. For simulations used in anesthesiology, studies that describe advances in scenario development, the development of scoring rubrics, and the validation of assessment results are synthesized. Based on the summary of relevant research, psychometric requirements for practical implementation of simulation-based assessments in anesthesiology are forwarded. As technology expands, and simulation-based education and evaluation takes on a larger role in patient safety initiatives, the groundbreaking work conducted to date can serve as a model for those individuals and organizations that are responsible for developing, scoring, or validating simulation-based education and assessment programs in anesthesiology.

A Multi-Scale Method for Dynamics Simulation in Continuum Solvent Models I: Finite-Difference Algorithm for Navier-Stokes Equation.

PubMed

Xiao, Li; Cai, Qin; Li, Zhilin; Zhao, Hongkai; Luo, Ray

2014-11-25

A multi-scale framework is proposed for more realistic molecular dynamics simulations in continuum solvent models by coupling a molecular mechanics treatment of solute with a fluid mechanics treatment of solvent. This article reports our initial efforts to formulate the physical concepts necessary for coupling the two mechanics and develop a 3D numerical algorithm to simulate the solvent fluid via the Navier-Stokes equation. The numerical algorithm was validated with multiple test cases. The validation shows that the algorithm is effective and stable, with observed accuracy consistent with our design.

A Damage Model for the Simulation of Delamination in Advanced Composites under Variable-Mode Loading

NASA Technical Reports Server (NTRS)

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

2006-01-01

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

Quantifying Uncertainty in Model Predictions for the Pliocene (Plio-QUMP): Initial results

USGS Publications Warehouse

Pope, J.O.; Collins, M.; Haywood, A.M.; Dowsett, H.J.; Hunter, S.J.; Lunt, D.J.; Pickering, S.J.; Pound, M.J.

2011-01-01

Examination of the mid-Pliocene Warm Period (mPWP; ~. 3.3 to 3.0. Ma BP) provides an excellent opportunity to test the ability of climate models to reproduce warm climate states, thereby assessing our confidence in model predictions. To do this it is necessary to relate the uncertainty in model simulations of mPWP climate to uncertainties in projections of future climate change. The uncertainties introduced by the model can be estimated through the use of a Perturbed Physics Ensemble (PPE). Developing on the UK Met Office Quantifying Uncertainty in Model Predictions (QUMP) Project, this paper presents the results from an initial investigation using the end members of a PPE in a fully coupled atmosphere-ocean model (HadCM3) running with appropriate mPWP boundary conditions. Prior work has shown that the unperturbed version of HadCM3 may underestimate mPWP sea surface temperatures at higher latitudes. Initial results indicate that neither the low sensitivity nor the high sensitivity simulations produce unequivocally improved mPWP climatology relative to the standard. Whilst the high sensitivity simulation was able to reconcile up to 6 ??C of the data/model mismatch in sea surface temperatures in the high latitudes of the Northern Hemisphere (relative to the standard simulation), it did not produce a better prediction of global vegetation than the standard simulation. Overall the low sensitivity simulation was degraded compared to the standard and high sensitivity simulations in all aspects of the data/model comparison. The results have shown that a PPE has the potential to explore weaknesses in mPWP modelling simulations which have been identified by geological proxies, but that a 'best fit' simulation will more likely come from a full ensemble in which simulations that contain the strengths of the two end member simulations shown here are combined. ?? 2011 Elsevier B.V.

A microcontroller-based simulation of dural venous sinus injury for neurosurgical training.

PubMed

Cleary, Daniel R; Siler, Dominic A; Whitney, Nathaniel; Selden, Nathan R

2018-05-01

OBJECTIVE Surgical simulation has the potential to supplement and enhance traditional resident training. However, the high cost of equipment and limited number of available scenarios have inhibited wider integration of simulation in neurosurgical education. In this study the authors provide initial validation of a novel, low-cost simulation platform that recreates the stress of surgery using a combination of hands-on, model-based, and computer elements. Trainee skill was quantified using multiple time and performance measures. The simulation was initially validated using trainees at the start of their intern year. METHODS The simulation recreates intraoperative superior sagittal sinus injury complicated by air embolism. The simulator model consists of 2 components: a reusable base and a disposable craniotomy pack. The simulator software is flexible and modular to allow adjustments in difficulty or the creation of entirely new clinical scenarios. The reusable simulator base incorporates a powerful microcomputer and multiple sensors and actuators to provide continuous feedback to the software controller, which in turn adjusts both the screen output and physical elements of the model. The disposable craniotomy pack incorporates 3D-printed sections of model skull and brain, as well as artificial dura that incorporates a model sagittal sinus. RESULTS Twelve participants at the 2015 Western Region Society of Neurological Surgeons postgraduate year 1 resident course ("boot camp") provided informed consent and enrolled in a study testing the prototype device. Each trainee was required to successfully create a bilateral parasagittal craniotomy, repair a dural sinus tear, and recognize and correct an air embolus. Participant stress was measured using a heart rate wrist monitor. After participation, each resident completed a 13-question categorical survey. CONCLUSIONS All trainee participants experienced tachycardia during the simulation, although the point in the simulation at which they experienced tachycardia varied. Survey results indicated that participants agreed the simulation was realistic, created stress, and was a useful tool in training neurosurgical residents. This simulator represents a novel, low-cost approach for hands-on training that effectively teaches and tests residents without risk of patient injury.

Computer Modeling and Simulation of Bullet Impact to the Human Thorax

DTIC Science & Technology

2000-06-01

manufacturers into the design and assessment stag~e of their body armor systems. V50 36 testing as used by body armor manufacturers experimentally identifies a...was due to the use of numerical integration by the experimenters at AFIP to obtain the velocities and displacements. In order to set a standard for... numerical integration. As such, in the sternum velocity graph, the initial downward motion of the experimental results, dependent upon the initial negative

Care initiation area yields dramatic results.

PubMed

2009-03-01

The ED at Gaston Memorial Hospital in Gastonia, NC, has achieved dramatic results in key department metrics with a Care Initiation Area (CIA) and a physician in triage. Here's how the ED arrived at this winning solution: Leadership was trained in and implemented the Kaizen method, which eliminates redundant or inefficient process steps. Simulation software helped determine additional space needed by analyzing arrival patterns and other key data. After only two days of meetings, new ideas were implemented and tested.

Initial SVS Integrated Technology Evaluation Flight Test Requirements and Hardware Architecture

NASA Technical Reports Server (NTRS)

Harrison, Stella V.; Kramer, Lynda J.; Bailey, Randall E.; Jones, Denise R.; Young, Steven D.; Harrah, Steven D.; Arthur, Jarvis J.; Parrish, Russell V.

2003-01-01

This document presents the flight test requirements for the Initial Synthetic Vision Systems Integrated Technology Evaluation flight Test to be flown aboard NASA Langley's ARIES aircraft and the final hardware architecture implemented to meet these requirements. Part I of this document contains the hardware, software, simulator, and flight operations requirements for this light test as they were defined in August 2002. The contents of this section are the actual requirements document that was signed for this flight test. Part II of this document contains information pertaining to the hardware architecture that was realized to meet these requirements as presented to and approved by a Critical Design Review Panel prior to installation on the B-757 Airborne Research Integrated Experiments Systems (ARIES) airplane. This information includes a description of the equipment, block diagrams of the architecture, layouts of the workstations, and pictures of the actual installations.

Annual progress report on the NSRR experiments, (21)

NASA Astrophysics Data System (ADS)

1992-05-01

Fuel behavior studies under simulated reactivity-initiated accident (RIA) conditions have been performed in the Nuclear Safety Research Reactor (NSRR) since 1975. This report gives the results of experiments performed from April, 1989 through March, 1990 and discussions of them. A total of 41 tests were carried out during this period. The tests are distinguished into pre-irradiated fuel tests and fresh fuel tests; the former includes 2 JMTR pre-irradiated fuel tests, 2 PWR pre-irradiated fuel tests, and 2 BWR pre-irradiated fuel tests, and the latter includes 6 standard fuel tests (6 SP(center dot)CP scoping tests), 7 power and cooling condition parameter tests (4 flow shrouded fuel tests, 1 bundle simulation test, 1 fully water-filled vessel test, 1 high pressure/high temperature loop test), 12 special fuel tests (3 stainless steel clad fuel tests, 3 improved PWR fuel tests, 6 improved BWR fuel tests), 3 severe fuel damage tests (1 high temperature flooding test, 1 flooding behavior observation test, 1 debris coolability test), 3 fast breeder reactor fuel tests (2 moderator material characteristic measurement tests, 1 fuel behavior observation test), and 2 miscellaneous tests (2 preliminary tests for pre-irradiated fuel tests).

Evaluation Of Risk And Possible Mitigation Schemes For Previously Unidentified Hazards

NASA Technical Reports Server (NTRS)

Linzey, William; McCutchan, Micah; Traskos, Michael; Gilbrech, Richard; Cherney, Robert; Slenski, George; Thomas, Walter, III

2006-01-01

This report presents the results of arc track testing conducted to determine if such a transfer of power to un-energized wires is possible and/or likely during an arcing event, and to evaluate an array of protection schemes that may significantly reduce the possibility of such a transfer. The results of these experiments may be useful for determining the level of protection necessary to guard against spurious voltage and current being applied to safety critical circuits. It was not the purpose of these experiments to determine the probability of the initiation of an arc track event only if an initiation did occur could it cause the undesired event: an inadvertent thruster firing. The primary wire insulation used in the Orbiter is aromatic polyimide, or Kapton , a construction known to arc track under certain conditions [3]. Previous Boeing testing has shown that arc tracks can initiate in aromatic polyimide insulated 28 volts direct current (VDC) power circuits using more realistic techniques such as chafing with an aluminum blade (simulating the corner of an avionics box or lip of a wire tray), or vibration of an aluminum plate against a wire bundle [4]. Therefore, an arc initiation technique was chosen that provided a reliable and consistent technique of starting the arc and not a realistic simulation of a scenario on the vehicle. Once an arc is initiated, the current, power and propagation characteristics of the arc depend on the power source, wire gauge and insulation type, circuit protection and series resistance rather than type of initiation. The initiation method employed for these tests was applying an oil and graphite mixture to the ends of a powered twisted pair wire. The flight configuration of the heater circuits, the fuel/oxider (or ox) wire, and the RCS jet solenoid were modeled in the test configuration so that the behavior of these components during an arcing event could be studied. To determine if coil activation would occur with various protection wire schemes, 145 tests were conducted using various fuel/ox wire alternatives (shielded and unshielded) and/or different combinations of polytetrafuloroethylene (PTFE), Mystik tape and convoluted wraps to prevent unwanted coil activation. Test results were evaluated along with other pertinent data and information to develop a mitigation strategy for an inadvertent RCS firing. The SSP evaluated civilian aircraft wiring failures to search for aging trends in assessing the wire-short hazard. Appendix 2 applies Weibull statistical methods to the same data with a similar purpose.

A Free-flight Wind Tunnel for Aerodynamic Testing at Hypersonic Speeds

NASA Technical Reports Server (NTRS)

Seiff, Alvin

1954-01-01

The supersonic free-flight wind tunnel is a facility at the Ames Laboratory of the NACA in which aerodynamic test models are gun-launched at high speed and directed upstream through the test section of a supersonic wind tunnel. In this way, test Mach numbers up to 10 have been attained and indications are that still higher speeds will be realized. An advantage of this technique is that the air and model temperatures simulate those of flight through the atmosphere. Also the Reynolds numbers are high. Aerodynamic measurements are made from photographic observation of the model flight. Instruments and techniques have been developed for measuring the following aerodynamic properties: drag, initial lift-curve slope, initial pitching-moment-curve slope, center of pressure, skin friction, boundary-layer transition, damping in roll, and aileron effectiveness. (author)

Coupled thermal stress simulations of ductile tearing

DOE PAGES

Neilsen, Michael K.; Dion, Kristin

2016-03-01

Predictions for ductile tearing of a geometrically complex Ti-6Al-4V plate were generated using a Unified Creep Plasticity Damage model in fully coupled thermal stress simulations. Uniaxial tension and butterfly shear tests performed at displacement rates of 0.0254 and 25.4 mm/s were also simulated. Results from these simulations revealed that the material temperature increase due to plastic work can have a dramatic effect on material ductility predictions in materials that exhibit little strain hardening. Furthermore, this occurs because the temperature increase causes the apparent hardening of the material to decrease which leads to the initiation of deformation localization and subsequent ductilemore » tearing earlier in the loading process.« less

Predictive validity of driving-simulator assessments following traumatic brain injury: a preliminary study.

PubMed

Lew, Henry L; Poole, John H; Lee, Eun Ha; Jaffe, David L; Huang, Hsiu-Chen; Brodd, Edward

2005-03-01

To evaluate whether driving simulator and road test evaluations can predict long-term driving performance, we conducted a prospective study on 11 patients with moderate to severe traumatic brain injury. Sixteen healthy subjects were also tested to provide normative values on the simulator at baseline. At their initial evaluation (time-1), subjects' driving skills were measured during a 30-minute simulator trial using an automated 12-measure Simulator Performance Index (SPI), while a trained observer also rated their performance using a Driving Performance Inventory (DPI). In addition, patients were evaluated on the road by a certified driving evaluator. Ten months later (time-2), family members observed patients driving for at least 3 hours over 4 weeks and rated their driving performance using the DPI. At time-1, patients were significantly impaired on automated SPI measures of driving skill, including: speed and steering control, accidents, and vigilance to a divided-attention task. These simulator indices significantly predicted the following aspects of observed driving performance at time-2: handling of automobile controls, regulation of vehicle speed and direction, higher-order judgment and self-control, as well as a trend-level association with car accidents. Automated measures of simulator skill (SPI) were more sensitive and accurate than observational measures of simulator skill (DPI) in predicting actual driving performance. To our surprise, the road test results at time-1 showed no significant relation to driving performance at time-2. Simulator-based assessment of patients with brain injuries can provide ecologically valid measures that, in some cases, may be more sensitive than a traditional road test as predictors of long-term driving performance in the community.

The WRF-CMAQ Integrated On-Line Modeling System: Development, Testing, and Initial Applications

EPA Science Inventory

Traditionally, atmospheric chemistry-transport and meteorology models have been applied in an off-line paradigm, in which archived output on the dynamical state of the atmosphere simulated using the meteorology model is used to drive transport and chemistry calculations of atmos...

The LHCb Detector at the LHC

NASA Astrophysics Data System (ADS)

LHCb Collaboration; Alves, A. Augusto, Jr.; Filho, L. M. Andrade; Barbosa, A. F.; Bediaga, I.; Cernicchiaro, G.; Guerrer, G.; Lima, H. P., Jr.; Machado, A. A.; Magnin, J.; Marujo, F.; de Miranda, J. M.; Reis, A.; Santos, A.; Toledo, A.; Akiba, K.; Amato, S.; de Paula, B.; de Paula, L.; da Silva, T.; Gandelman, M.; Lopes, J. H.; Maréchal, B.; Moraes, D.; Polycarpo, E.; Rodrigues, F.; Ballansat, J.; Bastian, Y.; Boget, D.; DeBonis, I.; Coco, V.; David, P. Y.; Decamp, D.; Delebecque, P.; Drancourt, C.; Dumont-Dayot, N.; Girard, C.; Lieunard, B.; Minard, M. N.; Pietrzyk, B.; Rambure, T.; Rospabe, G.; T'Jampens, S.; Ajaltouni, Z.; Bohner, G.; Bonnefoy, R.; Borras, D.; Carloganu, C.; Chanal, H.; Conte, E.; Cornat, R.; Crouau, M.; Delage, E.; Deschamps, O.; Henrard, P.; Jacquet, P.; Lacan, C.; Laubser, J.; Lecoq, J.; Lefèvre, R.; Magne, M.; Martemiyanov, M.; Mercier, M.-L.; Monteil, S.; Niess, V.; Perret, P.; Reinmuth, G.; Robert, A.; Suchorski, S.; Arnaud, K.; Aslanides, E.; Babel, J.; Benchouk, C.; Cachemiche, J.-P.; Cogan, J.; Derue, F.; Dinkespiler, B.; Duval, P.-Y.; Garonne, V.; Favard, S.; LeGac, R.; Leon, F.; Leroy, O.; Liotard, P.-L.; Marin, F.; Menouni, M.; Ollive, P.; Poss, S.; Roche, A.; Sapunov, M.; Tocco, L.; Viaud, B.; Tsaregorodtsev, A.; Amhis, Y.; Barrand, G.; Barsuk, S.; Beigbeder, C.; Beneyton, R.; Breton, D.; Callot, O.; Charlet, D.; D'Almagne, B.; Duarte, O.; Fulda-Quenzer, F.; Jacholkowska, A.; Jean-Marie, B.; Lefrancois, J.; Machefert, F.; Robbe, P.; Schune, M.-H.; Tocut, V.; Videau, I.; Benayoun, M.; David, P.; DelBuono, L.; Gilles, G.; Domke, M.; Futterschneider, H.; Ilgner, Ch; Kapusta, P.; Kolander, M.; Krause, R.; Lieng, M.; Nedos, M.; Rudloff, K.; Schleich, S.; Schwierz, R.; Spaan, B.; Wacker, K.; Warda, K.; Agari, M.; Bauer, C.; Baumeister, D.; Bulian, N.; Fuchs, H. P.; Fallot-Burghardt, W.; Glebe, T.; Hofmann, W.; Knöpfle, K. T.; Löchner, S.; Ludwig, A.; Maciuc, F.; Sanchez Nieto, F.; Schmelling, M.; Schwingenheuer, B.; Sexauer, E.; Smale, N. J.; Trunk, U.; Voss, H.; Albrecht, J.; Bachmann, S.; Blouw, J.; Deissenroth, M.; Deppe, H.; Dreis, H. B.; Eisele, F.; Haas, T.; Hansmann-Menzemer, S.; Hennenberger, S.; Knopf, J.; Moch, M.; Perieanu, A.; Rabenecker, S.; Rausch, A.; Rummel, C.; Rusnyak, R.; Schiller, M.; Stange, U.; Uwer, U.; Walter, M.; Ziegler, R.; Avoni, G.; Balbi, G.; Bonifazi, F.; Bortolotti, D.; Carbone, A.; D'Antone, I.; Galli, D.; Gregori, D.; Lax, I.; Marconi, U.; Peco, G.; Vagnoni, V.; Valenti, G.; Vecchi, S.; Bonivento, W.; Cardini, A.; Cadeddu, S.; DeLeo, V.; Deplano, C.; Furcas, S.; Lai, A.; Oldeman, R.; Raspino, D.; Saitta, B.; Serra, N.; Baldini, W.; Brusa, S.; Chiozzi, S.; Cotta Ramusino, A.; Evangelisti, F.; Franconieri, A.; Germani, S.; Gianoli, A.; Guoming, L.; Landi, L.; Malaguti, R.; Padoan, C.; Pennini, C.; Savriè, M.; Squerzanti, S.; Zhao, T.; Zhu, M.; Bizzeti, A.; Graziani, G.; Lenti, M.; Lenzi, M.; Maletta, F.; Pennazzi, S.; Passaleva, G.; Veltri, M.; Alfonsi, M.; Anelli, M.; Balla, A.; Battisti, A.; Bencivenni, G.; Campana, P.; Carletti, M.; Ciambrone, P.; Corradi, G.; Dané, E.; Di Virgilio, A.; DeSimone, P.; Felici, G.; Forti, C.; Gatta, M.; Lanfranchi, G.; Murtas, F.; Pistilli, M.; Poli Lener, M.; Rosellini, R.; Santoni, M.; Saputi, A.; Sarti, A.; Sciubba, A.; Zossi, A.; Ameri, M.; Cuneo, S.; Fontanelli, F.; Gracco, V.; Miní, G.; Parodi, M.; Petrolini, A.; Sannino, M.; Vinci, A.; Alemi, M.; Arnaboldi, C.; Bellunato, T.; Calvi, M.; Chignoli, F.; DeLucia, A.; Galotta, G.; Mazza, R.; Matteuzzi, C.; Musy, M.; Negri, P.; Perego, D.; Pessina, G.; Auriemma, G.; Bocci, V.; Buccheri, A.; Chiodi, G.; Di Marco, S.; Iacoangeli, F.; Martellotti, G.; Nobrega, R.; Pelosi, A.; Penso, G.; Pinci, D.; Rinaldi, W.; Rossi, A.; Santacesaria, R.; Satriano, C.; Carboni, G.; Iannilli, M.; Massafferri Rodrigues, A.; Messi, R.; Paoluzzi, G.; Sabatino, G.; Santovetti, E.; Satta, A.; Amoraal, J.; van Apeldoorn, G.; Arink, R.; van Bakel, N.; Band, H.; Bauer, Th; Berkien, A.; van Beuzekom, M.; Bos, E.; Bron, Ch; Ceelie, L.; Doets, M.; van der Eijk, R.; Fransen, J.-P.; de Groen, P.; Gromov, V.; Hierck, R.; Homma, J.; Hommels, B.; Hoogland, W.; Jans, E.; Jansen, F.; Jansen, L.; Jaspers, M.; Kaan, B.; Koene, B.; Koopstra, J.; Kroes, F.; Kraan, M.; Langedijk, J.; Merk, M.; Mos, S.; Munneke, B.; Palacios, J.; Papadelis, A.; Pellegrino, A.; van Petten, O.; du Pree, T.; Roeland, E.; Ruckstuhl, W.; Schimmel, A.; Schuijlenburg, H.; Sluijk, T.; Spelt, J.; Stolte, J.; Terrier, H.; Tuning, N.; Van Lysebetten, A.; Vankov, P.; Verkooijen, J.; Verlaat, B.; Vink, W.; de Vries, H.; Wiggers, L.; Ybeles Smit, G.; Zaitsev, N.; Zupan, M.; Zwart, A.; van den Brand, J.; Bulten, H. J.; de Jong, M.; Ketel, T.; Klous, S.; Kos, J.; M'charek, B.; Mul, F.; Raven, G.; Simioni, E.; Cheng, J.; Dai, G.; Deng, Z.; Gao, Y.; Gong, G.; Gong, H.; He, J.; Hou, L.; Li, J.; Qian, W.; Shao, B.; Xue, T.; Yang, Z.; Zeng, M.; Muryn, B.; Ciba, K.; Oblakowska-Mucha, A.; Blocki, J.; Galuszka, K.; Hajduk, L.; Michalowski, J.; Natkaniec, Z.; Polok, G.; Stodulski, M.; Witek, M.; Brzozowski, K.; Chlopik, A.; Gawor, P.; Guzik, Z.; Nawrot, A.; Srednicki, A.; Syryczynski, K.; Szczekowski, M.; Anghel, D. V.; Cimpean, A.; Coca, C.; Constantin, F.; Cristian, P.; Dumitru, D. D.; Dumitru, D. T.; Giolu, G.; Kusko, C.; Magureanu, C.; Mihon, Gh; Orlandea, M.; Pavel, C.; Petrescu, R.; Popescu, S.; Preda, T.; Rosca, A.; Rusu, V. L.; Stoica, R.; Stoica, S.; Tarta, P. D.; Filippov, S.; Gavrilov, Yu; Golyshkin, L.; Gushchin, E.; Karavichev, O.; Klubakov, V.; Kravchuk, L.; Kutuzov, V.; Laptev, S.; Popov, S.; Aref'ev, A.; Bobchenko, B.; Dolgoshein, V.; Egorychev, V.; Golutvin, A.; Gushchin, O.; Konoplyannikov, A.; Korolko, I.; Kvaratskheliya, T.; Machikhiliyan, I.; Malyshev, S.; Mayatskaya, E.; Prokudin, M.; Rusinov, D.; Rusinov, V.; Shatalov, P.; Shchutska, L.; Tarkovskiy, E.; Tayduganov, A.; Voronchev, K.; Zhiryakova, O.; Bobrov, A.; Bondar, A.; Eidelman, S.; Kozlinsky, A.; Shekhtman, L.; Beloous, K. S.; Dzhelyadin, R. I.; Gelitsky, Yu V.; Gouz, Yu P.; Kachnov, K. G.; Kobelev, A. S.; Matveev, V. D.; Novikov, V. P.; Obraztsov, V. F.; Ostankov, A. P.; Romanovsky, V. I.; Rykalin, V. I.; Soldatov, A. P.; Soldatov, M. M.; Tchernov, E. N.; Yushchenko, O. P.; Bochin, B.; Bondar, N.; Fedorov, O.; Golovtsov, V.; Guets, S.; Kashchuk, A.; Lazarev, V.; Maev, O.; Neustroev, P.; Sagidova, N.; Spiridenkov, E.; Volkov, S.; Vorobyev, An; Vorobyov, A.; Aguilo, E.; Bota, S.; Calvo, M.; Comerma, A.; Cano, X.; Dieguez, A.; Herms, A.; Lopez, E.; Luengo, S.; Garra, J.; Garrido, Ll; Gascon, D.; Gaspar de Valenzuela, A.; Gonzalez, C.; Graciani, R.; Grauges, E.; Perez Calero, A.; Picatoste, E.; Riera, J.; Rosello, M.; Ruiz, H.; Vilasis, X.; Xirgu, X.; Adeva, B.; Cid Vidal, X.; MartÉnez Santos, D.; Esperante Pereira, D.; Fungueiriño Pazos, J. L.; Gallas Torreira, A.; Gómez, C. Lois; Pazos Alvarez, A.; Pérez Trigo, E.; Pló Casasús, M.; Rodriguez Cobo, C.; Rodríguez Pérez, P.; Saborido, J. J.; Seco, M.; Vazquez Regueiro, P.; Bartalini, P.; Bay, A.; Bettler, M.-O.; Blanc, F.; Borel, J.; Carron, B.; Currat, C.; Conti, G.; Dormond, O.; Ermoline, Y.; Fauland, P.; Fernandez, L.; Frei, R.; Gagliardi, G.; Gueissaz, N.; Haefeli, G.; Hicheur, A.; Jacoby, C.; Jalocha, P.; Jimenez-Otero, S.; Hertig, J.-P.; Knecht, M.; Legger, F.; Locatelli, L.; Moser, J.-R.; Needham, M.; Nicolas, L.; Perrin-Giacomin, A.; Perroud, J.-P.; Potterat, C.; Ronga, F.; Schneider, O.; Schietinger, T.; Steele, D.; Studer, L.; Tareb, M.; Tran, M. T.; van Hunen, J.; Vervink, K.; Villa, S.; Zwahlen, N.; Bernet, R.; Büchler, A.; Gassner, J.; Lehner, F.; Sakhelashvili, T.; Salzmann, C.; Sievers, P.; Steiner, S.; Steinkamp, O.; Straumann, U.; van Tilburg, J.; Vollhardt, A.; Volyanskyy, D.; Ziegler, M.; Dovbnya, A.; Ranyuk, Yu; Shapoval, I.; Borisova, M.; Iakovenko, V.; Kyva, V.; Kovalchuk, O.; Okhrimenko, O.; Pugatch, V.; Pylypchenko, Yu; Adinolfi, M.; Brook, N. H.; Head, R. D.; Imong, J. P.; Lessnoff, K. A.; Metlica, F. C. D.; Muir, A. J.; Rademacker, J. H.; Solomin, A.; Szczypka, P. M.; Barham, C.; Buszello, C.; Dickens, J.; Gibson, V.; Haines, S.; Harrison, K.; Jones, C. R.; Katvars, S.; Kerzel, U.; Lazzeroni, C.; Li, Y. Y.; Rogers, G.; Storey, J.; Skottowe, H.; Wotton, S. A.; Adye, T. J.; Densham, C. J.; Easo, S.; Franek, B.; Loveridge, P.; Morrow, D.; Morris, J. V.; Nandakumar, R.; Nardulli, J.; Papanestis, A.; Patrick, G. N.; Ricciardi, S.; Woodward, M. L.; Zhang, Z.; Chamonal, R. J. U.; Clark, P. J.; Clarke, P.; Eisenhardt, S.; Gilardi, N.; Khan, A.; Kim, Y. M.; Lambert, R.; Lawrence, J.; Main, A.; McCarron, J.; Mclean, C.; Muheim, F.; Osorio-Oliveros, A. F.; Playfer, S.; Styles, N.; Xie, Y.; Bates, A.; Carson, L.; da Cunha Marinho, F.; Doherty, F.; Eklund, L.; Gersabeck, M.; Haddad, L.; Macgregor, A. A.; Melone, J.; McEwan, F.; Petrie, D. M.; Paterson, S. K.; Parkes, C.; Pickford, A.; Rakotomiaramanana, B.; Rodrigues, E.; Saavedra, A. F.; Soler, F. J. P.; Szumlak, T.; Viret, S.; Allebone, L.; Awunor, O.; Back, J.; Barber, G.; Barnes, C.; Cameron, B.; Clark, D.; Clark, I.; Dornan, P.; Duane, A.; Eames, C.; Egede, U.; Girone, M.; Greenwood, S.; Hallam, R.; Hare, R.; Howard, A.; Jolly, S.; Kasey, V.; Khaleeq, M.; Koppenburg, P.; Miller, D.; Plackett, R.; Price, D.; Reece, W.; Savage, P.; Savidge, T.; Simmons, B.; Vidal-Sitjes, G.; Websdale, D.; Affolder, A.; Anderson, J. S.; Biagi, S. F.; Bowcock, T. J. V.; Carroll, J. L.; Casse, G.; Cooke, P.; Donleavy, S.; Dwyer, L.; Hennessy, K.; Huse, T.; Hutchcroft, D.; Jones, D.; Lockwood, M.; McCubbin, M.; McNulty, R.; Muskett, D.; Noor, A.; Patel, G. D.; Rinnert, K.; Shears, T.; Smith, N. A.; Southern, G.; Stavitski, I.; Sutcliffe, P.; Tobin, M.; Traynor, S. M.; Turner, P.; Whitley, M.; Wormald, M.; Wright, V.; Bibby, J. H.; Brisbane, S.; Brock, M.; Charles, M.; Cioffi, C.; Gligorov, V. V.; Handford, T.; Harnew, N.; Harris, F.; John, M. J. J.; Jones, M.; Libby, J.; Martin, L.; McArthur, I. A.; Muresan, R.; Newby, C.; Ottewell, B.; Powell, A.; Rotolo, N.; Senanayake, R. S.; Somerville, L.; Soroko, A.; Spradlin, P.; Sullivan, P.; Stokes-Rees, I.; Topp-Jorgensen, S.; Xing, F.; Wilkinson, G.; Artuso, M.; Belyaev, I.; Blusk, S.; Lefeuvre, G.; Menaa, N.; Menaa-Sia, R.; Mountain, R.; Skwarnicki, T.; Stone, S.; Wang, J. C.; Abadie, L.; Aglieri-Rinella, G.; Albrecht, E.; André, J.; Anelli, G.; Arnaud, N.; Augustinus, A.; Bal, F.; Barandela Pazos, M. C.; Barczyk, A.; Bargiotti, M.; Batista Lopes, J.; Behrendt, O.; Berni, S.; Binko, P.; Bobillier, V.; Braem, A.; Brarda, L.; Buytaert, J.; Camilleri, L.; Cambpell, M.; Castellani, G.; Cataneo, F.; Cattaneo, M.; Chadaj, B.; Charpentier, P.; Cherukuwada, S.; Chesi, E.; Christiansen, J.; Chytracek, R.; Clemencic, M.; Closier, J.; Collins, P.; Colrain, P.; Cooke, O.; Corajod, B.; Corti, G.; D'Ambrosio, C.; Damodaran, B.; David, C.; de Capua, S.; Decreuse, G.; Degaudenzi, H.; Dijkstra, H.; Droulez, J.-P.; Duarte Ramos, D.; Dufey, J. P.; Dumps, R.; Eckstein, D.; Ferro-Luzzi, M.; Fiedler, F.; Filthaut, F.; Flegel, W.; Forty, R.; Fournier, C.; Frank, M.; Frei, C.; Gaidioz, B.; Gaspar, C.; Gayde, J.-C.; Gavillet, P.; Go, A.; Gracia Abril, G.; Graulich, J.-S.; Giudici, P.-A.; Guirao Elias, A.; Guglielmini, P.; Gys, T.; Hahn, F.; Haider, S.; Harvey, J.; Hay, B.; Hernando Morata, J.-A.; Herranz Alvarez, J.; van Herwijnen, E.; Hilke, H. J.; von Holtey, G.; Hulsbergen, W.; Jacobsson, R.; Jamet, O.; Joram, C.; Jost, B.; Kanaya, N.; Knaster Refolio, J.; Koestner, S.; Koratzinos, M.; Kristic, R.; Lacarrère, D.; Lasseur, C.; Lastovicka, T.; Laub, M.; Liko, D.; Lippmann, C.; Lindner, R.; Losasso, M.; Maier, A.; Mair, K.; Maley, P.; Mato Vila, P.; Moine, G.; Morant, J.; Moritz, M.; Moscicki, J.; Muecke, M.; Mueller, H.; Nakada, T.; Neufeld, N.; Ocariz, J.; Padilla Aranda, C.; Parzefall, U.; Patel, M.; Pepe-Altarelli, M.; Piedigrossi, D.; Pivk, M.; Pokorski, W.; Ponce, S.; Ranjard, F.; Riegler, W.; Renaud, J.; Roiser, S.; Rossi, A.; Roy, L.; Ruf, T.; Ruffinoni, D.; Saladino, S.; Sambade Varela, A.; Santinelli, R.; Schmelling, S.; Schmidt, B.; Schneider, T.; Schöning, A.; Schopper, A.; Seguinot, J.; Snoeys, W.; Smith, A.; Smith, A. C.; Somogyi, P.; Stoica, R.; Tejessy, W.; Teubert, F.; Thomas, E.; Toledo Alarcon, J.; Ullaland, O.; Valassi, A.; Vannerem, P.; Veness, R.; Wicht, P.; Wiedner, D.; Witzeling, W.; Wright, A.; Wyllie, K.; Ypsilantis, T.

2008-08-01

The LHCb experiment is dedicated to precision measurements of CP violation and rare decays of B hadrons at the Large Hadron Collider (LHC) at CERN (Geneva). The initial configuration and expected performance of the detector and associated systems, as established by test beam measurements and simulation studies, is described.

Energy balance during underwater implosion of ductile metallic cylinders.

PubMed

Chamberlin, Ryan E; Guzas, Emily L; Ambrico, Joseph M

2014-11-01

Energy-based metrics are developed and applied to a numerical test case of implosion of an underwater pressure vessel. The energy metrics provide estimates of the initial energy in the system (potential energy), the energy released into the fluid as a pressure pulse, the energy absorbed by the imploding structure, and the energy absorbed by air trapped within the imploding structure. The primary test case considered is the implosion of an aluminum cylinder [diameter: 2.54 cm (1 in.), length: 27.46 cm (10.81 in.)] that collapses flat in a mode-2 shape with minimal fracture. The test case indicates that the structure absorbs the majority (92%) of the initial energy in the system. Consequently, the energy emitted as a pressure pulse into the fluid is a small fraction, approximately 5%, of the initial energy. The energy absorbed by the structure and the energy emitted into the fluid are calculated for additional simulations of underwater pressure vessel implosions. For all cases investigated, there is minimal fracture in the collapse, the structure absorbs more than 80% of the initial energy of the system, and the released pressure pulse carries away less than 6% of the initial energy.

Computer Simulation of Ejection Seat Performance and Preliminary Correlation with Empirical Data

DTIC Science & Technology

1980-04-01

L. . .. . 3 I r AFFDL-TR-79-31 50 TABLE OF CONTENTS SECTION PAGE I INTRODUCTION 1 1I SAFEST COMPUTER PROGRAM DESCRIPTION 8 III HITECH ...ZEARTH vs TIME 49E-I1A 53 34 ZEARTH vs XEARTH 49E-IIA 54 AFFDL-TR-79-3150 LIST OF TABLES TABLE PAGE 1 ACES II EVENT-TIME SEQUENCE 3 2 HITECH 49E-JlF...Initial Conditions 13 3 HITECH 49E-I1A Initial Conditions 14 4 HITECH Program Test Data Summary 15 5 SAFEST 49E-JIF Initial Conditions 20 6 SAFEST 49E-IIA

Peridynamic Applications for Orthotropic Materials

DTIC Science & Technology

2012-09-26

test and a vibration excitation of a laminated beam. An SEN (single edge notch) test of a 0° laminated plate was simulated by peridynamics and the...computational results matched very well with published experimental results. Fracture initiation and crack path of laminated plates with different fiber...Dwivedi [1] modeled the propagation of single-edge notch (SEN) in 0° laminated plate using cohesizve zone method. Xu [2] and Hu [3] proposed a two

Computer Programs for Prediction of Lightning Induced Voltages in Aircraft Electrical Circuits

DTIC Science & Technology

1975-04-01

8217-Mnnmn " ■*> i ■ : mmmmim*mmemmmMmmmmmam*t*ammi m ■■>■ ■ ,-,.->»^~—~—-. ■ - m^m Test techniques and equipment have been designed for subjecting com...are still on the drawing board, when there is as yet no aircraft on which to run tests . To fulfill this need, a program was initiated by the Air...aluated by full-scale simulated lightning tests of the external assemblies in question. Government specifications for some of these devices or

Stress corrosion crack initiation of alloy 600 in PWR primary water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhai, Ziqing; Toloczko, Mychailo B.; Olszta, Matthew J.

Stress corrosion crack (SCC) initiation of three mill-annealed (MA) alloy 600 heats in simulated pressurized water reactor primary water has been investigated using constant load tests equipped with in-situ direct current potential drop (DCPD) measurement capabilities. SCC initiation times were greatly reduced by a small amount of cold work. Shallow intergranular (IG) attack and/or cracks were found on most high-energy grain boundaries intersecting the surface with only a small fraction evolving into larger cracks and IGSCC growth. Crack depth profiles were measured and related to DCPD-detected initiation response. Processes controlling the SCC initiation in MA alloy 600 are discussed. INmore » PRESS, CORRECTED PROOF, 05/02/2017 - mfl« less

The Formation of the First Cosmic Structures and the Physics of the z ~ 20 Universe

NASA Astrophysics Data System (ADS)

O'Leary, Ryan M.; McQuinn, Matthew

2012-11-01

We perform a suite of cosmological simulations in the ΛCDM paradigm of the formation of the first structures in the universe prior to astrophysical reheating and reionization (15 <~ z < 200). These are the first simulations initialized in a manner that self-consistently accounts for the impact of pressure on the rate of growth of modes, temperature fluctuations in the gas, and the dark matter-baryon supersonic velocity difference. Even with these improvements, these are still difficult times to simulate accurately as the Jeans length of the cold intergalactic gas must be resolved while also capturing a representative sample of the universe. We explore the box size and resolution requirements to meet these competing objectives. Our simulations support the finding of recent studies that the dark matter-baryon velocity difference has a surprisingly large impact on the accretion of gas onto the first star-forming minihalos (which have masses of ~106 M ⊙). In fact, the halo gas is often significantly downwind of such halos and with lower densities in the simulations in which the baryons have a bulk flow with respect to the dark matter, modulating the formation of the first stars by the local value of this velocity difference. We also show that dynamical friction plays an important role in the nonlinear evolution of the dark matter-baryon differential velocity, acting to erase this velocity difference quickly in overdense gas, as well as sourcing visually apparent bow shocks and Mach cones throughout the universe. We use simulations with both the GADGET and Enzo cosmological codes to test the robustness of these conclusions. The comparison of these codes' simulations also provides a relatively controlled test of these codes themselves, allowing us to quantify some of the tradeoffs between the algorithms. For example, we find that particle coupling in GADGET between the gas and dark matter particles results in spurious growth that mimics nonlinear growth in the matter power spectrum for standard initial setups. This coupling is alleviated by using adaptive gravitational softening for the gas. In a companion paper, we use the simulations presented here to make detailed estimates for the impact of the dark matter-baryon velocity differential on redshifted 21 cm radiation. The initial conditions generator used in this study, CICSASS, can be publicly downloaded.

Impact of Simulation Training on Time to Initiation of Cardiopulmonary Resuscitation for First-Year Pediatrics Residents

PubMed Central

Ross, Joshua C.; Trainor, Jennifer L.; Eppich, Walter J.; Adler, Mark D.

2013-01-01

Background Pediatrics residents have few opportunities to perform cardiopulmonary resuscitation (CPR). Enhancing the quality of CPR is a key factor to improving outcomes for cardiopulmonary arrest in children and requires effective training strategies. Objective To evaluate the effectiveness of a simulation-based intervention to reduce first-year pediatrics residents' time for 3 critical actions in CPR: (1) call for help, (2) initiate bag-mask ventilation, and (3) initiate chest compressions. Methods A prospective study involving 31 first-year pediatrics residents at a children's hospital assigned to an early or late (control) intervention group. Residents underwent baseline assessment followed by repeat evaluations at 3 and 6 months. Time to critical actions was scored by video review. A 90-minute educational intervention focused on skill practice was conducted following baseline evaluation for the early-intervention group and following 3-month evaluation for the late-intervention group. Primary outcome was change in time to initiating the 3 critical actions. Change in time was analyzed by comparison of Kaplan-Meier curves, using the log-rank test. A 10% sample was timed by a second rater. Agreement was assessed using intraclass correlation (ICC). Results There was a statistically significant reduction in time for all 3 critical actions between baseline and 3-month evaluation in the early intervention group; this was not observed in the late (control) group. Rater agreement was excellent (ICC ≥ 0.99). Conclusions A simulation-based educational intervention significantly reduced time to initiation of CPR for first-year pediatrics residents. Simulation training facilitated acquisition of critical CPR skills that have the potential to impact patient outcome. PMID:24455010

Study of thermocline development inside a dual-media storage tank at the beginning of dynamic processes

NASA Astrophysics Data System (ADS)

Esence, Thibaut; Bayón, Rocío; Bruch, Arnaud; Rojas, Esther

2017-06-01

This work presents some of the experimental results obtained during a test campaign performed at the STONE facility of CEA-Grenoble in collaboration with CIEMAT-PSA supported by both the SFERA-II and the STAGE-STE project. This installation consists of a thermocline tank with thermal oil and rock/sand filler and the tests aimed to study the development of the temperature profile inside the tank at the beginning of charge/discharge processes. The investigation of how this profile is created and which is its dependence on the experimental parameters is crucial for predicting the behavior of a dual-media thermocline tank. Tests have been performed for dynamic processes from initial states with constant uniform temperature or with a thermal gradient already present due to a partial thermocline zone extraction in the former process. Tests at different fluid velocities and temperatures have been carried out as well, in order to evaluate the influence of operating conditions. When a dynamic process of charge or discharge is started, the development of the thermal front is very sharp and localized at tank top or bottom if initial tank temperature is uniform, whereas it is less pronounced if the test begins from a non-thermally uniform initial state. In terms of operating conditions, it has been observed that the development of the thermocline thermal front is independent not only of the fluid velocity but also of its temperatures, within the working ranges here considered. Due to these experimental results, it will be possible to improve simulation models for thermocline tanks and hence to predict their behavior more accurately, especially when they are implemented in annual simulations of CSP plants.

Factors affecting the simulated trajectory and intensification of Tropical Cyclone Yasi (2011)

NASA Astrophysics Data System (ADS)

Parker, Chelsea L.; Lynch, Amanda H.; Mooney, Priscilla A.

2017-09-01

This study investigates the sensitivity of the simulated trajectory, intensification, and forward speed of Tropical Cyclone Yasi to initial conditions, physical parameterizations, and sea surface temperatures. Yasi was a category 5 storm that made landfall in Queensland, Australia in February 2011. A series of simulations were performed using WRF-ARW v3.4.1 driven by ERA-Interim data at the lateral boundaries. To assess these simulations, a new simple skill score is devised to summarize the deviation from observed conditions at landfall. The results demonstrate the sensitivity to initial condition resolution and the need for a new initialization dataset. Ensemble testing of physics parameterizations revealed strong sensitivity to cumulus schemes, with a trade-off between trajectory and intensity accuracy. The Tiedtke scheme produces an accurate trajectory evolution and landfall location. The Kain Fritch scheme is associated with larger errors in trajectory due to a less active shallow convection over the ocean, leading to warmer temperatures at the 700 mb level and a stronger, more poleward steering flow. However, the Kain Fritsch scheme produces more accurate intensities and translation speeds. Tiedtke-derived intensities were weaker due to suppression of deep convection by active shallow convection. Accurate representation of the sea surface temperature through correcting a newly discovered SST lag in reanalysis data or increasing resolution of SST data can improve the simulation. Higher resolution increases relative vorticity and intensity. However, the sea surface boundary had a more pronounced effect on the simulation with the Tiedtke scheme due to its moisture convergence trigger and active shallow convection over the tropical ocean.

Effect of Particle Shape on Mechanical Behaviors of Rocks: A Numerical Study Using Clumped Particle Model

PubMed Central

Rong, Guan; Liu, Guang; Zhou, Chuang-bing

2013-01-01

Since rocks are aggregates of mineral particles, the effect of mineral microstructure on macroscopic mechanical behaviors of rocks is inneglectable. Rock samples of four different particle shapes are established in this study based on clumped particle model, and a sphericity index is used to quantify particle shape. Model parameters for simulation in PFC are obtained by triaxial compression test of quartz sandstone, and simulation of triaxial compression test is then conducted on four rock samples with different particle shapes. It is seen from the results that stress thresholds of rock samples such as crack initiation stress, crack damage stress, and peak stress decrease with the increasing of the sphericity index. The increase of sphericity leads to a drop of elastic modulus and a rise in Poisson ratio, while the decreasing sphericity usually results in the increase of cohesion and internal friction angle. Based on volume change of rock samples during simulation of triaxial compression test, variation of dilation angle with plastic strain is also studied. PMID:23997677

Effect of particle shape on mechanical behaviors of rocks: a numerical study using clumped particle model.

PubMed

Rong, Guan; Liu, Guang; Hou, Di; Zhou, Chuang-Bing

2013-01-01

Since rocks are aggregates of mineral particles, the effect of mineral microstructure on macroscopic mechanical behaviors of rocks is inneglectable. Rock samples of four different particle shapes are established in this study based on clumped particle model, and a sphericity index is used to quantify particle shape. Model parameters for simulation in PFC are obtained by triaxial compression test of quartz sandstone, and simulation of triaxial compression test is then conducted on four rock samples with different particle shapes. It is seen from the results that stress thresholds of rock samples such as crack initiation stress, crack damage stress, and peak stress decrease with the increasing of the sphericity index. The increase of sphericity leads to a drop of elastic modulus and a rise in Poisson ratio, while the decreasing sphericity usually results in the increase of cohesion and internal friction angle. Based on volume change of rock samples during simulation of triaxial compression test, variation of dilation angle with plastic strain is also studied.

Simulation of Watts Bar Unit 1 Initial Startup Tests with Continuous Energy Monte Carlo Methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Godfrey, Andrew T; Gehin, Jess C; Bekar, Kursat B

2014-01-01

The Consortium for Advanced Simulation of Light Water Reactors* is developing a collection of methods and software products known as VERA, the Virtual Environment for Reactor Applications. One component of the testing and validation plan for VERA is comparison of neutronics results to a set of continuous energy Monte Carlo solutions for a range of pressurized water reactor geometries using the SCALE component KENO-VI developed by Oak Ridge National Laboratory. Recent improvements in data, methods, and parallelism have enabled KENO, previously utilized predominately as a criticality safety code, to demonstrate excellent capability and performance for reactor physics applications. The highlymore » detailed and rigorous KENO solutions provide a reliable nu-meric reference for VERAneutronics and also demonstrate the most accurate predictions achievable by modeling and simulations tools for comparison to operating plant data. This paper demonstrates the performance of KENO-VI for the Watts Bar Unit 1 Cycle 1 zero power physics tests, including reactor criticality, control rod worths, and isothermal temperature coefficients.« less

Wake Numerical Simulation Based on the Park-Gauss Model and Considering Atmospheric Stability

NASA Astrophysics Data System (ADS)

Yang, Xiangsheng; Zhao, Ning; Tian, Linlin; Zhu, Jun

2016-06-01

In this paper, a new Park-Gauss model based on the assumption of the Park model and the Eddy-viscosity model is investigated to conduct the wake numerical simulation for solving a single wind turbine problem. The initial wake radius has been modified to improve the model’s numerical accuracy. Then the impact of the atmospheric stability based on the Park-Gauss model has been studied in the wake region. By the comparisons and the analyses of the test results, it turns out that the new Park-Gauss model could achieve better effects of the wind velocity simulation in the wake region. The wind velocity in the wake region recovers quickly under the unstable atmospheric condition provided the wind velocity is closest to the test result, and recovers slowly under stable atmospheric condition in case of the wind velocity is lower than the test result. Meanwhile, the wind velocity recovery falls in between the unstable and stable neutral atmospheric conditions.

Second Generation Crop Yield Models Review

NASA Technical Reports Server (NTRS)

Hodges, T. (Principal Investigator)

1982-01-01

Second generation yield models, including crop growth simulation models and plant process models, may be suitable for large area crop yield forecasting in the yield model development project. Subjective and objective criteria for model selection are defined and models which might be selected are reviewed. Models may be selected to provide submodels as input to other models; for further development and testing; or for immediate testing as forecasting tools. A plant process model may range in complexity from several dozen submodels simulating (1) energy, carbohydrates, and minerals; (2) change in biomass of various organs; and (3) initiation and development of plant organs, to a few submodels simulating key physiological processes. The most complex models cannot be used directly in large area forecasting but may provide submodels which can be simplified for inclusion into simpler plant process models. Both published and unpublished models which may be used for development or testing are reviewed. Several other models, currently under development, may become available at a later date.

A flight investigation of simulated data-link communications during single-pilot IFR flight. Volume 1: Experimental design and initial test

NASA Technical Reports Server (NTRS)

Parker, J. F., Jr.; Duffy, J. W.; Christensen, D. G.

1981-01-01

A Flight Data Console simulation of a digital communication link to replace the current voice communication system used in air traffic control (ATC) was developed. The study determined how a digital communications system reduces cockpit workload, improve, flight proficiency, and is acceptable to general aviation pilots. It is shown that instrument flight, including approach and landing, can be accomplished by using a digital data link system for ATC communication.

Magnetohydrodynamic Simulations of Black Hole Accretion Flows Using PATCHWORK, a Multi-Patch, multi-code approach

NASA Astrophysics Data System (ADS)

Avara, Mark J.; Noble, Scott; Shiokawa, Hotaka; Cheng, Roseanne; Campanelli, Manuela; Krolik, Julian H.

2017-08-01

A multi-patch approach to numerical simulations of black hole accretion flows allows one to robustly match numerical grid shape and equations solved to the natural structure of the physical system. For instance, a cartesian gridded patch can be used to cover coordinate singularities on a spherical-polar grid, increasing computational efficiency and better capturing the physical system through natural symmetries. We will present early tests, initial applications, and first results from the new MHD implementation of the PATCHWORK framework.

Study on underclad cracking in nuclear reactor vessel steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Horiya, T.; Takeda, T.; Yamato, K.

1985-02-01

Susceptibility to underclad cracking in nuclear reactor vessel steels, such as SA533 Grade B Class 1 and SA508 Class 2, was studied in detail. A convenient simulation test method using simulated HAZ specimens of small size has been developed for quantitative evaluation of susceptibility to underclad cracks. The method can predict precisely the cracking behavior in weldments of steels with relative low crack susceptibility. The effect of chemical compositions on susceptibility to the cracking was examined systematically using the developed simulation test method and the following index was obtained from the test results: U = 20(V) + 7(C) + 4(Mo)more » + (Cr) + (Cu) - 0.5(Mn) + 1.5 log(X) X = Al . . . Al/2N less than or equal to 1 X = 2N . . . Al/2N > 1 It was confirmed that the new index (U) is useful for the prediction of crack susceptibility of the nuclear vessel steels; i.e., no crack initiation is detected in weldments in the roller bend test for steels having U value below 0.90.« less

ELUCID—Exploring the Local Universe with the reConstructed Initial Density Field. II. Reconstruction Diagnostics, Applied to Numerical Halo Catalogs

NASA Astrophysics Data System (ADS)

Tweed, Dylan; Yang, Xiaohu; Wang, Huiyuan; Cui, Weiguang; Zhang, Youcai; Li, Shijie; Jing, Y. P.; Mo, H. J.

2017-05-01

The ELUCID project aims to build a series of realistic cosmological simulations that reproduce the spatial and mass distributions of the galaxies as observed in the Sloan Digital Sky Survey. This requires powerful reconstruction techniques to create constrained initial conditions (ICs). We test the reconstruction method by applying it to several N-body simulations. We use two medium-resolution simulations, which each produced three additional constrained N-body simulations. We compare the resulting friend-of-friend catalogs by using the particle indexes as tracers, and quantify the quality of the reconstruction by varying the main smoothing parameter. The cross-identification method we use proves to be efficient, and the results suggest that the most massive reconstructed halos are effectively traced from the same Lagrangian regions in the ICs. A preliminary time-dependence analysis indicates that high-mass-end halos converge only at a redshift close to the reconstruction redshift. This suggests that, for earlier snapshots, only collections of progenitors may be effectively cross-identified.

Mesoscale Simulations of a Florida Sea Breeze Using the PLACE Land Surface Model Coupled to a 1.5-Order Turbulence Parameterization

NASA Technical Reports Server (NTRS)

Lynn, Barry H.; Stauffer, David R.; Wetzel, Peter J.; Tao, Wei-Kuo; Perlin, Natal; Baker, R. David; Munoz, Ricardo; Boone, Aaron; Jia, Yiqin

1999-01-01

A sophisticated land-surface model, PLACE, the Parameterization for Land Atmospheric Convective Exchange, has been coupled to a 1.5-order turbulent kinetic energy (TKE) turbulence sub-model. Both have been incorporated into the Penn State/National Center for Atmospheric Research (PSU/NCAR) mesoscale model MM5. Such model improvements should have their greatest effect in conditions where surface contrasts dominate over dynamic processes, such as the simulation of warm-season, convective events. A validation study used the newly coupled model, MM5 TKE-PLACE, to simulate the evolution of Florida sea-breeze moist convection during the Convection and Precipitation Electrification Experiment (CaPE). Overall, eight simulations tested the sensitivity of the MM5 model to combinations of the new and default model physics, and initialization of soil moisture and temperature. The TKE-PLACE model produced more realistic surface sensible heat flux, lower biases for surface variables, more realistic rainfall, and cloud cover than the default model. Of the 8 simulations with different factors (i.e., model physics or initialization), TKE-PLACE compared very well when each simulation was ranked in terms of biases of the surface variables and rainfall, and percent and root mean square of cloud cover. A factor separation analysis showed that a successful simulation required the inclusion of a multi-layered, land surface soil vegetation model, realistic initial soil moisture, and higher order closure of the planetary boundary layer (PBL). These were needed to realistically model the effect of individual, joint, and synergistic contributions from the land surface and PBL on the CAPE sea-breeze, Lake Okeechobee lake breeze, and moist convection.

OpenSim as a preliminary kinematic testing platform for the development of total knee arthroplasty implants.

PubMed

Chan, Hao Yang; Walker, Peter S

2018-05-18

The design of a total knee replacement implant needs to take account the complex surfaces of the knee which it is replacing. Ensuring design performance of the implant requires in vitro testing of the implant. A considerable amount of time is required to produce components and evaluate them inside an experimental setting. Numerous adjustments in the design of an implant and testing each individual design can be time consuming and expensive. Our solution is to use the OpenSim simulation software to rapidly test multiple design configurations of implants. This study modeled a testing rig which characterized the motion and laxity of knee implants. Three different knee implant designs were used to test and validate the accuracy of the simulation: symmetrical, asymmetric, and anatomic. Kinematics were described as distances measured from the center of each femoral condyle to a plane intersecting the most posterior points of the tibial condyles between 0 and 135° of flexion with 15° increments. Excluding the initial flexion measurement (∼0°) results, the absolute differences between all experimental and simulation results (neutral path, anterior-posterior shear, internal-external torque) for the symmetric, asymmetric, and anatomical designs were 1.98 mm ± 1.15, 1.17 mm ± 0.89, and 1.24 mm ± 0.97, respectively. Considering all designs, the accuracy of the simulation across all tests was 1.46 mm ± 1.07. It was concluded that the results of the simulation were an acceptable representation of the testing rig and hence applicable as a design tool for new total knees. Copyright © 2018 Elsevier Ltd. All rights reserved.

Simulation of gait and gait initiation associated with body oscillating behavior in the gravity environment on the moon, mars and Phobos.

PubMed

Brenière, Y

2001-04-01

A double-inverted pendulum model of body oscillations in the frontal plane during stepping [Brenière and Ribreau (1998) Biol Cybern 79: 337-345] proposed an equivalent model for studying the body oscillating behavior induced by step frequency in the form of: (1) a kinetic body parameter, the natural body frequency (NBF), which contains gravity and which is invariable for humans, (2) a parametric function of frequency, whose parameter is the NBF, which explicates the amplitude ratio of center of mass to center of foot pressure oscillation, and (3) a function of frequency which simulates the equivalent torque necessary for the control of the head-arms-trunk segment oscillations. Here, this equivalent model is used to simulate the duration of gait initiation, i.e., the duration necessary to initiate and execute the first step of gait in subgravity, as well as to calculate the step frequencies that would impose the same minimum and maximum amplitudes of the oscillating responses of the body center of mass, whatever the gravity value. In particular, this simulation is tested under the subgravity conditions of the Moon, Mars, and Phobos, where gravity is 1/6, 3/8, and 1/1600 times that on the Earth, respectively. More generally, the simulation allows us to establish and discuss the conditions for gait adaptability that result from the biomechanical constraints particular to each gravity system.

Low-Speed Flight Dynamic Tests and Analysis of the Orion Crew Module Drogue Parachute System

NASA Technical Reports Server (NTRS)

Hahne, David E.; Fremaux, C. Michael

2008-01-01

A test of a dynamically scaled model of the NASA Orion Crew Module (CM) with drogue parachutes was conducted in the NASA-Langley 20-Foot Vertical Spin Tunnel. The primary test objective was to assess the ability of the Orion Crew Module drogue parachute system to adequately stabilize the CM and reduce angular rates at low subsonic Mach numbers. Two attachment locations were tested: the current design nominal and an alternate. Experimental results indicated that the alternate attachment location showed a somewhat greater tendency to attenuate initial roll rate and reduce roll rate oscillations than the nominal location. Comparison of the experimental data to a Program To Optimize Simulated Trajectories (POST II) simulation of the experiment yielded results for the nominal attachment point that indicate differences between the low-speed pitch and yaw damping derivatives in the aerodynamic database and the physical model. Comparisons for the alternate attachment location indicate that riser twist plays a significant role in determining roll rate attenuation characteristics. Reevaluating the impact of the alternate attachment points using a simulation modified to account for these results showed significantly reduced roll rate attenuation tendencies when compared to the original simulation. Based on this modified simulation the alternate attachment point does not appear to offer a significant increase in allowable roll rate over the nominal configuration.

Design of a Resistively Heated Thermal Hydraulic Simulator for Nuclear Rocket Reactor Cores

NASA Technical Reports Server (NTRS)

Litchford, Ron J.; Foote, John P.; Ramachandran, Narayanan; Wang, Ten-See; Anghaie, Samim

2007-01-01

A preliminary design study is presented for a non-nuclear test facility which uses ohmic heating to replicate the thermal hydraulic characteristics of solid core nuclear reactor fuel element passages. The basis for this testing capability is a recently commissioned nuclear thermal rocket environments simulator, which uses a high-power, multi-gas, wall-stabilized constricted arc-heater to produce high-temperature pressurized hydrogen flows representative of reactor core environments, excepting radiation effects. Initially, the baseline test fixture for this non-nuclear environments simulator was configured for long duration hot hydrogen exposure of small cylindrical material specimens as a low cost means of evaluating material compatibility. It became evident, however, that additional functionality enhancements were needed to permit a critical examination of thermal hydraulic effects in fuel element passages. Thus, a design configuration was conceived whereby a short tubular material specimen, representing a fuel element passage segment, is surrounded by a backside resistive tungsten heater element and mounted within a self-contained module that inserts directly into the baseline test fixture assembly. With this configuration, it becomes possible to create an inward directed radial thermal gradient within the tubular material specimen such that the wall-to-gas heat flux characteristics of a typical fuel element passage are effectively simulated. The results of a preliminary engineering study for this innovative concept are fully summarized, including high-fidelity multi-physics thermal hydraulic simulations and detailed design features.

Coupling lateral bending and shearing mechanisms to define knee injury criteria for pedestrian safety.

PubMed

Mo, Fuhao; Masson, Catherine; Cesari, Dominique; Arnoux, Pierre Jean

2013-01-01

In car-pedestrian accidents, lateral bending and shearing kinematics have been identified as principal injury mechanisms causing permanent disabilities and impairments to the knee joint. Regarding the combined lateral bending and shearing contributions of knee joint kinematics, developing a coupled knee injury criterion is necessary for improving vehicle countermeasures to mitigate pedestrian knee injuries. The advantages of both experimental tests and finite element (FE) simulations were combined to determine the reliable injury tolerances of the knee joint. First, 7 isolated lower limb tests from postmortem human subjects (PMHS) were reported, with dynamic loading at a velocity of 20 km/h. With the intention of replicating relevant injury mechanisms of vehicle-pedestrian impacts, the experimental tests were categorized into 3 groups by the impact locations on the tibia: the distal end to prioritize pure bending, the middle diaphysis to have combined bending and shearing effects, and the proximal end to acquire pure shearing. Then, the corresponding FE model was employed to provide an additional way to determine exact injury occurrences and develop a robust knee injury criterion by the variation in both the lateral bending and shearing contributions through a sensitivity analysis of impact locations. Considering the experimental test results and the subsequent sensitivity analysis of FE simulations, both the tolerances and patterns of knee joint injuries were determined to be influenced by impact locations due to various combined contributions of lateral bending and shearing. Both medial collateral ligament and cruciate ligament failures were noted as the onsets of knee injuries, namely, initial injuries. Finally, a new injury criterion categorized by initial injury patterns of knee joint was proposed by coupling lateral bending and shearing levels. The developed injury criterion correlated the combined joint kinematics to initial knee injuries based on subsegment tests and FE simulations conducted with a biofidelic lower limb model. This provides a valuable way of predicting the risk of knee injury associated with vehicle-pedestrian crashes and thereby represents a further step to promote the design of vehicle countermeasures for pedestrian safety.

Multiyear Plan for Validation of EnergyPlus Multi-Zone HVAC System Modeling using ORNL's Flexible Research Platform

DOE Office of Scientific and Technical Information (OSTI.GOV)

Im, Piljae; Bhandari, Mahabir S.; New, Joshua Ryan

This document describes the Oak Ridge National Laboratory (ORNL) multiyear experimental plan for validation and uncertainty characterization of whole-building energy simulation for a multi-zone research facility using a traditional rooftop unit (RTU) as a baseline heating, ventilating, and air conditioning (HVAC) system. The project’s overarching objective is to increase the accuracy of energy simulation tools by enabling empirical validation of key inputs and algorithms. Doing so is required to inform the design of increasingly integrated building systems and to enable accountability for performance gaps between design and operation of a building. The project will produce documented data sets that canmore » be used to validate key functionality in different energy simulation tools and to identify errors and inadequate assumptions in simulation engines so that developers can correct them. ASHRAE Standard 140, Method of Test for the Evaluation of Building Energy Analysis Computer Programs (ASHRAE 2004), currently consists primarily of tests to compare different simulation programs with one another. This project will generate sets of measured data to enable empirical validation, incorporate these test data sets in an extended version of Standard 140, and apply these tests to the Department of Energy’s (DOE) EnergyPlus software (EnergyPlus 2016) to initiate the correction of any significant deficiencies. The fitness-for-purpose of the key algorithms in EnergyPlus will be established and demonstrated, and vendors of other simulation programs will be able to demonstrate the validity of their products. The data set will be equally applicable to validation of other simulation engines as well.« less

Anti-corrosion activities of apen-class inhibitive drug on aluminium alloy in simulated chloride environment

NASA Astrophysics Data System (ADS)

Fayomi, O. S. I.; Anawe, PAL; Ayoola, A. A.; Joseph, O. O.

2018-05-01

In this study, aluminium material normally used in the underlie ship was immersed in simulated sodium chloride environment and its degradation properties was evaluated. Investigation of corrosion rate and mass weight loss through gravimetric tests measurements showed that less mass loss was recorded for tests in sodium chloride with 3-(2'-chloro-6' fluorophenyl) and lowest corrosion rate values were found at 10%. On the other hand, the mass loss deteriorated in all 3-(2'-chloro-6' fluorophenyl) with less uniform corrosion. The existence of chloride dissolved the interfacial surface layer resulting into pit initiation and growth. It is found that corrosion degradation of aluminum is dependent on chloride and inhibitive concentration.

Collection and analysis of wind data for the evaluation of Wildland-Urban Interface Fire Dynamics Simulator

NASA Astrophysics Data System (ADS)

Espina, Chad Edward Obedoza

The Wildland Urban-Interface Fire Dynamics Simulator (WFDS) is a computer code that is currently being developed by the National Institute of Standards and Technology (NIST). WFDS has the capability of simulating wildland fire behavior with prescribed elements such vegetative and structural fuel, topography, and weather conditions. In this initial stage of the research, support for the development of WFDS focuses on the evaluation of a wind flow simulation on a very complex, outdoor terrain. This effort is preceded by the fabrication, installation and testing of wind-sensing equipment. Foremost, wind data gathered from different sites using various instruments are compared and evaluated. The data gathered in the Trails community of Rancho Bernardo is then presented and compared to select WFDS simulations. Systems consisting of a wind vane and anemometer are currently installed in the Trails community of Rancho Bernardo. They were installed by Professor Fletcher J. Miller and me using a lift that is attached to a telescoping crane. These instruments will gather the wind data needed to show the behavioral patterns of winds influenced by the topography and obstructions such as trees and houses. They are currently installed on top of light posts. These light posts were picked based on the path of the fire influenced by the Santa Ana winds that ravaged the community in 2007. The data from these instruments were graphically represented using a Matlab code that was developed specifically for the data sets. The Matlab graphing utility plots wind speed and wind direction along with matching polar plots. Other main features also include the ability to set a time range and compare two sites in one plot. There are other wind instruments currently being tested and being analyzed to ensure correct data is being recorded. These instruments will also expand to a wider range the wind data-gathering capabilities vertically. A Sound Detecting and Ranging (SoDAR) unit gathers wind speed and direction from the sound waves, initially emitted by the SoDAR to the atmosphere, that are reflected by the air flow above the unit. Wind data has been compared to the SoDAR unit with data from instruments installed on a meteorological tower operated by the National Oceanic and Atmospheric Administration (NOAA) located in northern California. Two more SoDARs are currently in Texas where initially they were deployed 400 meters apart of each other at an airfield. Also in the same airfield, the wind instrument of an Unmanned Aerial Vehicle (UAV) SuperBat was tested and compared to the SoDARs. Lastly, a self-contained wind instrument (Wind Dart) on a UAV that was developed by the University of Colorado was tested. The instrument was used while attached to the UAV Spectra. A static test was also done in San Diego State University's low speed wind tunnel. The wind data comparison from the SoDAR and meteorological tower in Lodi, California showed close tracking to each other both in wind speed and direction. The comparison of the wind data gathered by the two SoDARs in Texas also showed close tracking to each other. As for the Wind Dart, the data gathered from the instrument and UAV Spectra are not conclusive enough to validate the abilities of the Wind Dart. The experimental procedure in testing the Wind Dart on a moving platform must be further developed. Before the aerial test of the Wind Dart, it was first tested at San Diego State University's low speed tunnel. The detected wind speed by the Wind Dart closely matches the prescribed wind speed of the wind tunnel. The data between the UAV SuperBat and SoDARs showed close tracking. Data collected by the Rancho Bernardo wind instruments shows cyclical wind patterns in the neighborhood. Initial evaluation of select WFDS simulations show data that mimics data gathered from the field.

Thermodynamics of reformulated automotive fuels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zudkevitch, D.; Murthy, A.K.S.; Gmehling, J.

1995-06-01

Two methods for predicting Reid vapor pressure (Rvp) and initial vapor emissions of reformulated gasoline blends that contain one or more oxygenated compounds show excellent agreement with experimental data. In the first method, method A, D-86 distillation data for gasoline blends are used for predicting Rvp from a simulation of the mini dry vapor pressure equivalent (Dvpe) experiment. The other method, method B, relies on analytical information (PIANO analyses) of the base gasoline and uses classical thermodynamics for simulating the same Rvp equivalent (Rvpe) mini experiment. Method B also predicts composition and other properties for the fuel`s initial vapor emission.more » Method B, although complex, is more useful in that is can predict properties of blends without a D-86 distillation. An important aspect of method B is its capability to predict composition of initial vapor emissions from gasoline blends. Thus, it offers a powerful tool to planners of gasoline blending. Method B uses theoretically sound formulas, rigorous thermodynamic routines and uses data and correlations of physical properties that are in the public domain. Results indicate that predictions made with both methods agree very well with experimental values of Dvpe. Computer simulation methods were programmed and tested.« less

3D registration of surfaces for change detection in medical images

NASA Astrophysics Data System (ADS)

Fisher, Elizabeth; van der Stelt, Paul F.; Dunn, Stanley M.

1997-04-01

Spatial registration of data sets is essential for quantifying changes that take place over time in cases where the position of a patient with respect to the sensor has been altered. Changes within the region of interest can be problematic for automatic methods of registration. This research addresses the problem of automatic 3D registration of surfaces derived from serial, single-modality images for the purpose of quantifying changes over time. The registration algorithm utilizes motion-invariant, curvature- based geometric properties to derive an approximation to an initial rigid transformation to align two image sets. Following the initial registration, changed portions of the surface are detected and excluded before refining the transformation parameters. The performance of the algorithm was tested using simulation experiments. To quantitatively assess the registration, random noise at various levels, known rigid motion transformations, and analytically-defined volume changes were applied to the initial surface data acquired from models of teeth. These simulation experiments demonstrated that the calculated transformation parameters were accurate to within 1.2 percent of the total applied rotation and 2.9 percent of the total applied translation, even at the highest applied noise levels and simulated wear values.

Impact of Heterogeneity on Vadose Zone Drainage During Pumping: Numerical Simulations of the Borden Aquifer

NASA Astrophysics Data System (ADS)

Bunn, M. I.; Jones, J.; Endres, A. L.

2009-05-01

Unconfined aquifers are in direct contact with the earth's surface; hence, they are an important focus in groundwater recharge and contaminant transport studies. While pumping tests have long been used to quantify aquifer properties, the contribution of drainage from the vadose zone during pumping has been the subject of debate for decades. In 2001, a highly detailed data set was collected during a seven-day pumping test in the unconfined aquifer at CFB Borden, Ontario (Bevan et al., 2005). The frequent observation of moisture content profiles during the test has initiated a closer examination of the vadose zone response to pumping. The moisture profiles collected during the test were obtained using a neutron probe. The neutron data depicts a capillary fringe thickness that increases with both proximity to the pumping well and duration of pumping. This capillary fringe extension results in delayed drainage that persists to the end of the seven-day test with the shape of the transition zone remaining constant (Bevan et al., 2005). Simulations of the pumping test were conducted using Hydrogeosphere (Therrien et al., 2006). Initial simulations were completed based on the conceptual model of a homogeneous and slightly anisotropic aquifer. The simulation results replicated the observed piezometric response, but were unable to produce any change in the thickness of the capillary fringe. It was hypothesized that the discrepancy between observations and simulation results may be the result of assumptions such as the homogeneity of the hydraulic conductivity field. In an effort to replicate this potential mechanism for the observed extension, the conceptual model was updated to better reflect the mildly heterogeneous hydraulic conductivity field of the Borden aquifer. Conductivity fields were generated using the statistical description of the Borden aquifer given by Sudicky (1986) with an adjusted mean log conductivity to better approximate the observed piezometric response. The inclusion of heterogeneity appears to have little effect on the hydraulic head drawdown, or the thickness of the capillary fringe. Heterogeneity does lead to delayed drainage in the drier portion of the vadose zone, where volumetric water content is less than 0.13 m3/m3. This effect is more pronounced with proximity to the pumping well, and is negligible at 15 m from the well. The amount of excess moisture in the vadose zone does not appear to be a function of pumping duration.

A Static Burst Test for Composite Flywheel Rotors

NASA Astrophysics Data System (ADS)

Hartl, Stefan; Schulz, Alexander; Sima, Harald; Koch, Thomas; Kaltenbacher, Manfred

2016-06-01

High efficient and safe flywheels are an interesting technology for decentralized energy storage. To ensure all safety aspects, a static test method for a controlled initiation of a burst event for composite flywheel rotors is presented with nearly the same stress distribution as in the dynamic case, rotating with maximum speed. In addition to failure prediction using different maximum stress criteria and a safety factor, a set of tensile and compressive tests is carried out to identify the parameters of the used carbon fiber reinforced plastics (CFRP) material. The static finite element (FE) simulation results of the flywheel static burst test (FSBT) compare well to the quasistatic FE-simulation results of the flywheel rotor using inertia loads. Furthermore, it is demonstrated that the presented method is a very good controllable and observable possibility to test a high speed flywheel energy storage system (FESS) rotor in a static way. Thereby, a much more expensive and dangerous dynamic spin up test with possible uncertainties can be substituted.

Simulating the Impact Response of Full-Scale Composite Airframe Structures

NASA Technical Reports Server (NTRS)

Fasanella, Edwin L.; Jackson, Karen E.; Littell, Justin D.; Seal, Michael D.

2012-01-01

NASA Langley Research Center obtained a composite helicopter cabin structure in 2010 from the US Army's Survivable Affordable Repairable Airframe Program (SARAP) that was fabricated by Sikorsky Aircraft Corporation. The cabin had been subjected to a vertical drop test in 2008 to evaluate a tilting roof concept to limit the intrusion of overhead masses into the fuselage cabin. Damage to the cabin test article was limited primarily to the roof. Consequently, the roof area was removed and the remaining structure was cut into test specimens including a large subfloor section and a forward framed fuselage section. In 2011, NASA and Sikorsky entered into a cooperative research agreement to study the impact responses of composite airframe structures and to evaluate the capabilities of the explicit transient dynamic finite element code, LS-DYNA®, to simulate these responses including damage initiation and progressive failure. Most of the test articles were manufactured of graphite unidirectional tape composite with a thermoplastic resin system. However, the framed fuselage section was constructed primarily of a plain weave graphite fabric material with a thermoset resin system. Test data were collected from accelerometers and full-field photogrammetry. The focus of this paper will be to document impact testing and simulation results for the longitudinal impact of the subfloor section and the vertical drop test of the forward framed fuselage section.

Simulation trainer for practicing emergent open thoracotomy procedures.

PubMed

Hamilton, Allan J; Prescher, Hannes; Biffar, David E; Poston, Robert S

2015-07-01

An emergent open thoracotomy (OT) is a high-risk, low-frequency procedure uniquely suited for simulation training. We developed a cost-effective Cardiothoracic (CT) Surgery trainer and assessed its potential for improving technical and interprofessional skills during an emergent simulated OT. We modified a commercially available mannequin torso with artificial tissue models to create a custom CT Surgery trainer. The trainer's feasibility for simulating emergent OT was tested using a multidisciplinary CT team in three consecutive in situ simulations. Five discretely observable milestones were identified as requisite steps in carrying out an emergent OT; namely (1) diagnosis and declaration of a code situation, (2) arrival of the code cart, (3) arrival of the thoracotomy tray, (4) initiation of the thoracotomy incision, and (5) defibrillation of a simulated heart. The time required for a team to achieve each discrete step was measured by an independent observer over the course of each OT simulation trial and compared. Over the course of the three OT simulation trials conducted in the coronary care unit, there was an average reduction of 29.5% (P < 0.05) in the times required to achieve the five critical milestones. The time required to complete the whole OT procedure improved by 7 min and 31 s from the initial to the final trial-an overall improvement of 40%. In our preliminary evaluation, the CT Surgery trainer appears to be useful for improving team performance during a simulated emergent bedside OT in the coronary care unit. Copyright © 2015 Elsevier Inc. All rights reserved.

Design and landing dynamic analysis of reusable landing leg for a near-space manned capsule

NASA Astrophysics Data System (ADS)

Yue, Shuai; Nie, Hong; Zhang, Ming; Wei, Xiaohui; Gan, Shengyong

2018-06-01

To improve the landing performance of a near-space manned capsule under various landing conditions, a novel landing system is designed that employs double chamber and single chamber dampers in the primary and auxiliary struts, respectively. A dynamic model of the landing system is established, and the damper parameters are determined by employing the design method. A single-leg drop test with different initial pitch angles is then conducted to compare and validate the simulation model. Based on the validated simulation model, seven critical landing conditions regarding nine crucial landing responses are found by combining the radial basis function (RBF) surrogate model and adaptive simulated annealing (ASA) optimization method. Subsequently, the adaptability of the landing system under critical landing conditions is analyzed. The results show that the simulation effectively results match the test results, which validates the accuracy of the dynamic model. In addition, all of the crucial responses under their corresponding critical landing conditions satisfy the design specifications, demonstrating the feasibility of the landing system.

Initial Operation and Shakedown of the Nuclear Thermal Rocket Element Environmental Simulator (NTREES)

NASA Technical Reports Server (NTRS)

Emrich, William J., Jr.

2014-01-01

To support the on-going nuclear thermal propulsion effort, a state-of-the-art non nuclear experimental test setup has been constructed to evaluate the performance characteristics of candidate fuel element materials and geometries in representative environments. The facility to perform this testing is referred to as the Nuclear Thermal Rocket Element Environment Simulator (NTREES). This device can simulate the environmental conditions (minus the radiation) to which nuclear rocket fuel components will be subjected during reactor operation. Prototypical fuel elements mounted in the simulator are inductively heated in such a manner so as to accurately reproduce the temperatures and heat fluxes which would normally occur as a result of nuclear fission in addition to being exposed to flowing hydrogen. Recent upgrades to NTREES now allow power levels 24 times greater than those achievable in the previous facility configuration. This higher power operation will allow near prototypical power densities and flows to finally be achieved in most prototypical fuel elements.

Simulations in site error estimation for direction finders

NASA Astrophysics Data System (ADS)

López, Raúl E.; Passi, Ranjit M.

1991-08-01

The performance of an algorithm for the recovery of site-specific errors of direction finder (DF) networks is tested under controlled simulated conditions. The simulations show that the algorithm has some inherent shortcomings for the recovery of site errors from the measured azimuth data. These limitations are fundamental to the problem of site error estimation using azimuth information. Several ways for resolving or ameliorating these basic complications are tested by means of simulations. From these it appears that for the effective implementation of the site error determination algorithm, one should design the networks with at least four DFs, improve the alignment of the antennas, and increase the gain of the DFs as much as it is compatible with other operational requirements. The use of a nonzero initial estimate of the site errors when working with data from networks of four or more DFs also improves the accuracy of the site error recovery. Even for networks of three DFs, reasonable site error corrections could be obtained if the antennas could be well aligned.

Material Model Evaluation of a Composite Honeycomb Energy Absorber

NASA Technical Reports Server (NTRS)

Jackson, Karen E.; Annett, Martin S.; Fasanella, Edwin L.; Polanco, Michael A.

2012-01-01

A study was conducted to evaluate four different material models in predicting the dynamic crushing response of solid-element-based models of a composite honeycomb energy absorber, designated the Deployable Energy Absorber (DEA). Dynamic crush tests of three DEA components were simulated using the nonlinear, explicit transient dynamic code, LS-DYNA . In addition, a full-scale crash test of an MD-500 helicopter, retrofitted with DEA blocks, was simulated. The four material models used to represent the DEA included: *MAT_CRUSHABLE_FOAM (Mat 63), *MAT_HONEYCOMB (Mat 26), *MAT_SIMPLIFIED_RUBBER/FOAM (Mat 181), and *MAT_TRANSVERSELY_ANISOTROPIC_CRUSHABLE_FOAM (Mat 142). Test-analysis calibration metrics included simple percentage error comparisons of initial peak acceleration, sustained crush stress, and peak compaction acceleration of the DEA components. In addition, the Roadside Safety Verification and Validation Program (RSVVP) was used to assess similarities and differences between the experimental and analytical curves for the full-scale crash test.

Orbiter aborts from boost: Presimulation report

NASA Technical Reports Server (NTRS)

Backman, H. D.; Brechka, K. G.

1972-01-01

A description of a hybrid simulation of the 040C orbiter aborting from boost to specified landing site is provided. The simulation starts when the abort is initiated and continues until a terminal energy state (associated with the selected landing site) is reached. At abort it is assumed that all SRM's are jettisoned with the external tank remaining with the orbiter. The simulation described has six degrees of freedom with the vehicle simulated as a rigid body. A conventional form of autopilot is provided to control engine gimbaling during powered flight. An ideal form of an autopilot is provided to test conventional autopilot function and provide pseudo RCS function during coasting flight. The simulation is proposed to provide means for studies of abort guidance function and to gain information concerning ability to control the abort trajectory.

Simulation of the XV-15 tilt rotor research aircraft

NASA Technical Reports Server (NTRS)

Churchill, G. B.; Dugan, D. C.

1982-01-01

The effective use of simulation from issuance of the request for proposal through conduct of a flight test program for the XV-15 Tilt Rotor Research Aircraft is discussed. From program inception, simulation complemented all phases of XV-15 development. The initial simulation evaluations during the source evaluation board proceedings contributed significantly to performance and stability and control evaluations. Eight subsequent simulation periods provided major contributions in the areas of control concepts; cockpit configuration; handling qualities; pilot workload; failure effects and recovery procedures; and flight boundary problems and recovery procedures. The fidelity of the simulation also made it a valuable pilot training aid, as well as a suitable tool for military and civil mission evaluations. Simulation also provided valuable design data for refinement of automatic flight control systems. Throughout the program, fidelity was a prime issue and resulted in unique data and methods for fidelity evaluation which are presented and discussed.

Simulating extreme environments: Ergonomic evaluation of Chinese pilot performance and heat stress tolerance.

PubMed

Li, Jing; Tian, Yinsheng; Ding, Li; Zou, Huijuan; Ren, Zhaosheng; Shi, Liyong; Feathers, David; Wang, Ning

2015-06-05

High-temperatures in the cockpit environment can adversely influence pilot behavior and performance. To investigate the impact of high thermal environments on Chinese pilot performance in a simulated cockpit environment. Ten subjects volunteered to participate in the tests under 40°C and 45°C high-temperature simulations in an environmentally controlled chamber. Measures such as grip strength, perception, dexterity, somatic sense reaction, and analytical reasoning were taken. The results were compared to the Combined Index of Heat Stress (CIHS). CIHS exceeded the heat stress safety limit after 45 min under 40°C, grip strength decreased by 12% and somatic perception became 2.89 times larger than the initial value. In the case of 45°C, CIHS exceeded the safety limit after only 20 min, while the grip strength decreased just by 3.2% and somatic perception increased to 4.36 times larger than the initial value. Reaction and finger dexterity were not statistically different from baseline measurements, but the error rate of analytical reasoning test rose remarkably. Somatic perception was the most sensitive index to high-temperature, followed by grip strength. Results of this paper may help to improve environmental control design of new fighter cockpit and for pilot physiology and cockpit environment ergonomics research for Chinese pilots.

Initial Cognitive Performance Predicts Longitudinal Aviator Performance

PubMed Central

Jo, Booil; Adamson, Maheen M.; Kennedy, Quinn; Noda, Art; Hernandez, Beatriz; Zeitzer, Jamie M.; Friedman, Leah F.; Fairchild, Kaci; Scanlon, Blake K.; Murphy, Greer M.; Taylor, Joy L.

2011-01-01

Objectives. The goal of the study was to improve prediction of longitudinal flight simulator performance by studying cognitive factors that may moderate the influence of chronological age. Method. We examined age-related change in aviation performance in aircraft pilots in relation to baseline cognitive ability measures and aviation expertise. Participants were aircraft pilots (N = 276) aged 40–77.9. Flight simulator performance and cognition were tested yearly; there were an average of 4.3 (± 2.7; range 1–13) data points per participant. Each participant was classified into one of the three levels of aviation expertise based on Federal Aviation Administration pilot proficiency ratings: least, moderate, or high expertise. Results. Addition of measures of cognitive processing speed and executive function to a model of age-related change in aviation performance significantly improved the model. Processing speed and executive function performance interacted such that the slowest rate of decline in flight simulator performance was found in aviators with the highest scores on tests of these abilities. Expertise was beneficial to pilots across the age range studied; however, expertise did not show evidence of reducing the effect of age. Discussion. These data suggest that longitudinal performance on an important real-world activity can be predicted by initial assessment of relevant cognitive abilities. PMID:21586627

Flow and fracture behavior of aluminum alloy 6082-T6 at different tensile strain rates and triaxialities.

PubMed

Chen, Xuanzhen; Peng, Yong; Peng, Shan; Yao, Song; Chen, Chao; Xu, Ping

2017-01-01

This study aims to investigate the flow and fracture behavior of aluminum alloy 6082-T6 (AA6082-T6) at different strain rates and triaxialities. Two groups of Charpy impact tests were carried out to further investigate its dynamic impact fracture property. A series of tensile tests and numerical simulations based on finite element analysis (FEA) were performed. Experimental data on smooth specimens under various strain rates ranging from 0.0001~3400 s-1 shows that AA6082-T6 is rather insensitive to strain rates in general. However, clear rate sensitivity was observed in the range of 0.001~1 s-1 while such a characteristic is counteracted by the adiabatic heating of specimens under high strain rates. A Johnson-Cook constitutive model was proposed based on tensile tests at different strain rates. In this study, the average stress triaxiality and equivalent plastic strain at facture obtained from numerical simulations were used for the calibration of J-C fracture model. Both of the J-C constitutive model and fracture model were employed in numerical simulations and the results was compared with experimental results. The calibrated J-C fracture model exhibits higher accuracy than the J-C fracture model obtained by the common method in predicting the fracture behavior of AA6082-T6. Finally, the Scanning Electron Microscope (SEM) of fractured specimens with different initial stress triaxialities were analyzed. The magnified fractographs indicate that high initial stress triaxiality likely results in dimple fracture.

Genus Topology of Structure in the Sloan Digital Sky Survey: Model Testing

NASA Astrophysics Data System (ADS)

Gott, J. Richard, III; Hambrick, D. Clay; Vogeley, Michael S.; Kim, Juhan; Park, Changbom; Choi, Yun-Young; Cen, Renyue; Ostriker, Jeremiah P.; Nagamine, Kentaro

2008-03-01

We measure the three-dimensional topology of large-scale structure in the Sloan Digital Sky Survey (SDSS). This allows the genus statistic to be measured with unprecedented statistical accuracy. The sample size is now sufficiently large to allow the topology to be an important tool for testing galaxy formation models. For comparison, we make mock SDSS samples using several state-of-the-art N-body simulations: the Millennium run of Springel et al. (10 billion particles), the Kim & Park CDM models (1.1 billion particles), and the Cen & Ostriker hydrodynamic code models (8.6 billion cell hydro mesh). Each of these simulations uses a different method for modeling galaxy formation. The SDSS data show a genus curve that is broadly characteristic of that produced by Gaussian random-phase initial conditions. Thus, the data strongly support the standard model of inflation where Gaussian random-phase initial conditions are produced by random quantum fluctuations in the early universe. But on top of this general shape there are measurable differences produced by nonlinear gravitational effects and biasing connected with galaxy formation. The N-body simulations have been tuned to reproduce the power spectrum and multiplicity function but not topology, so topology is an acid test for these models. The data show a "meatball" shift (only partly due to the Sloan Great Wall of galaxies) that differs at the 2.5 σ level from the results of the Millenium run and the Kim & Park dark halo models, even including the effects of cosmic variance.

Cr(VI)-contaminated groundwater remediation with simulated permeable reactive barrier (PRB) filled with natural pyrite as reactive material: Environmental factors and effectiveness.

PubMed

Liu, Yuanyuan; Mou, Haiyan; Chen, Liqun; Mirza, Zakaria A; Liu, Li

2015-11-15

Permeable reactive barriers (PRBs) are efficient technologies for in situ remediation of contaminated groundwater, the effectiveness of which greatly depends on the reactive media filled. Natural pyrite is an iron sulfide material with a very low content of iron and sulfur, and a mining waste which is a potential material for Cr(VI) immobilization. In this study, we conducted a series of batch tests to research the effects of typical environmental factors on Cr(VI) removal and also simulated PRB filled with natural pyrite to investigate its effectiveness, in order to find a both environmentally and economically fine method for groundwater remediation. Batch tests showed that pH had the significant impact on Cr(VI) removal with an apparently higher efficiency under acidic conditions, and dissolved oxygen (DO) would inhibit Cr(VI) reduction; a relatively high initial Cr(VI) concentration would decrease the rate of Cr(VI) sorption; ionic strength and natural organic matter resulted in no significant effects on Cr(VI) removal. Column tests demonstrated that the simulated PRB with natural pyrite as the reactive media was considerably effective for removing Cr(VI) from groundwater, with a sorption capability of 0.6222 mg Cr per gram of natural pyrite at an initial Cr(VI) concentration of 10mg/L at pH 5.5 in an anoxic environment. Copyright © 2015 Elsevier B.V. All rights reserved.

Physical simulation and theoretical evolution for ground fissures triggered by underground coal mining

PubMed Central

Yu, Xiang; Yang, Yi; Yang, Zeng-Qiang

2018-01-01

Underground coal mining activities are prone to cause movement and breakage in geological strata and also lead to mining subsidence and even ground fissures. Along the direction working panel advancing, ground fissures may occur in roof in front and/or behind working panel. However, the investigations of previous similarity tests in lab only emphasize on the region behind working panel. By improving strata material property in construction and mounting artificial pressure devices, two physical simulation tests were conducted and successfully investigated the simulated results. Then, the mechanical model of “cantilever beam and elastic foundation beam” was proposed to calculate the stress distribution and the crack initiation angle in overlying strata and it well explains the mechanisms of ground fissures generation and propagation. Results show that, the maximum internal force in roof always occurred in front of working panel. However, because the void space in gob due to excavation is large enough to cause the bend and rotation of roof strata, compare to the triaxially compressed region in front of working panel, the roof always broke off at some positions above gob since the stress concentration resulting from such bend and rotation of strata could easily reach the limit strength of strata rocks. Also, the length of cantilever beam changed dynamically as respect to the panel advancing and the breakage intervals. Thus, the breakage position where the internal force first reached the limit tensile strength is not fixed and there will be two different kinds of relative positions between the crack initiation point and the working panel. The crack initiation direction is always perpendicular to the internal force, and the crack propagation direction is affected by the initiation angle, overburden-separation degree and the position of the hydraulic shields. If there is no overburden-separation or less, the roofs will break off as a composite beam and the propagation direction will be roughly along the central line between the initial broken point and the support position. Otherwise, the roof strata will bend with the support shields moving forward, then the fracture angle will be close to the initiation angle and the fault surface will be stepped. PMID:29513703

Physical simulation and theoretical evolution for ground fissures triggered by underground coal mining.

PubMed

Yang, Jing-Hu; Yu, Xiang; Yang, Yi; Yang, Zeng-Qiang

2018-01-01

Underground coal mining activities are prone to cause movement and breakage in geological strata and also lead to mining subsidence and even ground fissures. Along the direction working panel advancing, ground fissures may occur in roof in front and/or behind working panel. However, the investigations of previous similarity tests in lab only emphasize on the region behind working panel. By improving strata material property in construction and mounting artificial pressure devices, two physical simulation tests were conducted and successfully investigated the simulated results. Then, the mechanical model of "cantilever beam and elastic foundation beam" was proposed to calculate the stress distribution and the crack initiation angle in overlying strata and it well explains the mechanisms of ground fissures generation and propagation. Results show that, the maximum internal force in roof always occurred in front of working panel. However, because the void space in gob due to excavation is large enough to cause the bend and rotation of roof strata, compare to the triaxially compressed region in front of working panel, the roof always broke off at some positions above gob since the stress concentration resulting from such bend and rotation of strata could easily reach the limit strength of strata rocks. Also, the length of cantilever beam changed dynamically as respect to the panel advancing and the breakage intervals. Thus, the breakage position where the internal force first reached the limit tensile strength is not fixed and there will be two different kinds of relative positions between the crack initiation point and the working panel. The crack initiation direction is always perpendicular to the internal force, and the crack propagation direction is affected by the initiation angle, overburden-separation degree and the position of the hydraulic shields. If there is no overburden-separation or less, the roofs will break off as a composite beam and the propagation direction will be roughly along the central line between the initial broken point and the support position. Otherwise, the roof strata will bend with the support shields moving forward, then the fracture angle will be close to the initiation angle and the fault surface will be stepped.

Effects of High Temperature Exposures on Fatigue Life of Disk Superalloys

NASA Technical Reports Server (NTRS)

Gabb, Tim P.; Telesman, Jack; Kantzos, Pete T.; Smith, James W.; Browning, Paul F.

2004-01-01

The effects on fatigue life of high temperature exposures simulating service conditions were considered for two disk superalloys. Powder metallurgy processed, supersolvus heat treated Udimet (trademark) 720 and ME3 fatigue specimens were exposed in air at temperatures of 650 to 704 C, for times of 100 h to over 1000 h. They were then tested using conventional fatigue tests at 650 and 704 C, to determine the effects of exposure on fatigue resistance. Cyclic dwell verification tests were also performed to contrast the effects of intermixed exposures and fatigue cycles. The prior exposures reduced life by up to 70% and increased the scatter in life, compared to unexposed levels. Cyclic dwell tests reduced lives even more. Fractographic evaluations indicated the failure mode was shifted by the exposures and cyclic dwells from predominantly internal to often surface crack initiations. The increased scatter in life was related to the competition between internal crack initiations at inclusions or large grains producing longer lives, and surface crack initiations at an environmentally affected surface layer producing shorter lives.

Deep flaws in weldments of aluminum and titanium

NASA Technical Reports Server (NTRS)

Masters, J. N.; Engstrom, W. L.; Bixler, W. D.

1974-01-01

Surface flawed specimens of 2219-T87 and 6Al-4V STA titanium weldments were tested to determine static failure modes, failure strength, and fatigue flaw growth characteristics. Thicknesses selected for this study were purposely set at values where, for most test conditions, abrupt instability of the flaw at fracture would not be expected. Static tests for the aluminum weldments were performed at room, LN2 and LH2 temperatures. Titanium static tests for tests were performed at room and LH2 temperatures. Results of the static tests were used to plot curves relating initial flaw size to leakage- or failure-stresses (i.e. "failure" locus curves). Cyclic tests, for both materials, were then performed at room temperature, using initial flaws only slightly below the previously established failure locus for typical proof stress levels. Cyclic testing was performed on pairs of specimens, one with and one without a simulated proof test cycle. Comparisons were made then to determine the value and effect of proof testing as affected by the various variables of proof and operating stress, flaw shape, material thickness, and alloy.

Berthing simulator for space station and orbiter

NASA Technical Reports Server (NTRS)

Veerasamy, Sam

1991-01-01

The development of a real-time man-in-the-loop berthing simulator is in progress at NASA Lyndon B. Johnson Space Center (JSC) to conduct a parametric study and to measure forces during contact conditions of the actual docking mechanisms for the Space Station Freedom and the orbiter. In berthing, the docking ports of the Space Station and the orbiter are brought together using the orbiter robotic arm to control the relative motion of the vehicles. The berthing simulator consists of a dynamics docking test system (DDTS), computer system, simulator software, and workstations. In the DDTS, the Space Station, and the orbiter docking mechanisms are mounted on a six-degree-of-freedom (6 DOF) table and a fixed platform above the table. Six load cells are used on the fixed platform to measure forces during contact conditions of the docking mechanisms. Two Encore Concept 32/9780 computers are used to simulate the orbiter robotic arm and to operate the berthing simulator. A systematic procedure for a real-time dynamic initialization is being developed to synchronize the Space Station docking port trajectory with the 6 DOF table movement. The berthing test can be conducted manually or automatically and can be extended for any two orbiting vehicles using a simulated robotic arm. The real-time operation of the berthing simulator is briefly described.

Initial results on fault diagnosis of DSN antenna control assemblies using pattern recognition techniques

NASA Technical Reports Server (NTRS)

Smyth, P.; Mellstrom, J.

1990-01-01

Initial results obtained from an investigation using pattern recognition techniques for identifying fault modes in the Deep Space Network (DSN) 70 m antenna control loops are described. The overall background to the problem is described, the motivation and potential benefits of this approach are outlined. In particular, an experiment is described in which fault modes were introduced into a state-space simulation of the antenna control loops. By training a multilayer feed-forward neural network on the simulated sensor output, classification rates of over 95 percent were achieved with a false alarm rate of zero on unseen tests data. It concludes that although the neural classifier has certain practical limitations at present, it also has considerable potential for problems of this nature.

Simulation of water-table aquifers using specified saturated thickness

USGS Publications Warehouse

Sheets, Rodney A.; Hill, Mary C.; Haitjema, Henk M.; Provost, Alden M.; Masterson, John P.

2014-01-01

Simulating groundwater flow in a water-table (unconfined) aquifer can be difficult because the saturated thickness available for flow depends on model-calculated hydraulic heads. It is often possible to realize substantial time savings and still obtain accurate head and flow solutions by specifying an approximate saturated thickness a priori, thus linearizing this aspect of the model. This specified-thickness approximation often relies on the use of the “confined” option in numerical models, which has led to confusion and criticism of the method. This article reviews the theoretical basis for the specified-thickness approximation, derives an error analysis for relatively ideal problems, and illustrates the utility of the approximation with a complex test problem. In the transient version of our complex test problem, the specified-thickness approximation produced maximum errors in computed drawdown of about 4% of initial aquifer saturated thickness even when maximum drawdowns were nearly 20% of initial saturated thickness. In the final steady-state version, the approximation produced maximum errors in computed drawdown of about 20% of initial aquifer saturated thickness (mean errors of about 5%) when maximum drawdowns were about 35% of initial saturated thickness. In early phases of model development, such as during initial model calibration efforts, the specified-thickness approximation can be a very effective tool to facilitate convergence. The reduced execution time and increased stability obtained through the approximation can be especially useful when many model runs are required, such as during inverse model calibration, sensitivity and uncertainty analyses, multimodel analysis, and development of optimal resource management scenarios.

A Multi-Scale Method for Dynamics Simulation in Continuum Solvent Models I: Finite-Difference Algorithm for Navier-Stokes Equation

PubMed Central

Xiao, Li; Cai, Qin; Li, Zhilin; Zhao, Hongkai; Luo, Ray

2014-01-01

A multi-scale framework is proposed for more realistic molecular dynamics simulations in continuum solvent models by coupling a molecular mechanics treatment of solute with a fluid mechanics treatment of solvent. This article reports our initial efforts to formulate the physical concepts necessary for coupling the two mechanics and develop a 3D numerical algorithm to simulate the solvent fluid via the Navier-Stokes equation. The numerical algorithm was validated with multiple test cases. The validation shows that the algorithm is effective and stable, with observed accuracy consistent with our design. PMID:25404761

An educational initiative to improve medical student awareness about brain death.

PubMed

Lewis, Ariane; Howard, Jonathan; Watsula-Morley, Amanda; Gillespie, Colleen

2018-04-01

Medical student knowledge about brain death determination is limited. We describe an educational initiative to improve medical student awareness about brain death and assess the impact of this initiative. Beginning in July 2016, students at our medical school were required to attend a 90-min brain death didactic and simulation session during their neurology clerkship. Students completed a test immediately before and after participating in the initiative. Of the 145 students who participated in this educational initiative between July 2016 and June 2017, 124 (86%) consented to have their data used for research purposes as part of a medical education registry. Students correctly answered a median of 53% of questions (IQR 47-58%) on the pretest and 86% of questions (IQR 78-89%) on the posttest (p < .001). Comfort with both performing a brain death evaluation and talking to a family about brain death improved significantly after this initiative (18% of students were comfortable performing a brain death evaluation before the initiative and 86% were comfortable doing so after the initiative, p < .001; 18% were comfortable talking to a family about brain death before the initiative and 76% were comfortable doing so after the initiative, p < .001). Incorporation of simulation in undergraduate medical education is high-yield. At our medical school, knowledge about brain death and comfort performing a brain death exam or talking to a family about brain death was limited prior to development of this initiative, but awareness and comfort dealing with brain death improved significantly after this initiative. Copyright © 2018 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bostick, W.D.; Hoffmann, D.P.; Stevenson, R.J.

The category of sludges, filter cakes, and other waste processing residuals represent the largest volume of low-level mixed (hazardous and radioactive) wastes within the US Department of Energy (DOE) complex. Treatment of these wastes to minimize the mobility of contaminants, and to eliminate the presence of free water, is required under the Federal Facility Compliance Act agreements between DOE and the Environmental Protection Agency. In the text, we summarize the currently available data for several of the high priority mixed-waste sludge inventories within DOE. Los Alamos National Laboratory TA-50 Sludge and Rocky Flats Plant By-Pass Sludge are transuranic (TRU)-contaminated sludgesmore » that were isolated with the use of silica-based filter aids. The Oak Ridge Y-12 Plant West End Treatment Facility Sludge is predominantly calcium carbonate and biomass. The Oak Ridge K-25 Site Pond Waste is a large-volume waste stream, containing clay, silt, and other debris in addition to precipitated metal hydroxides. We formulate ``simulants`` for the waste streams described above, using cerium oxide as a surrogate for the uranium or plutonium present in the authentic material. Use of nonradiological surrogates greatly simplifies material handling requirements for initial treatability studies. The use of synthetic mixtures for initial treatability testing will facilitate compositional variation for use in conjunction with statistical design experiments; this approach may help to identify any ``operating window`` limitations. The initial treatability testing demonstrations utilizing these ``simulants`` will be based upon vitrification, although the materials are also amenable to testing grout-based and other stabilization procedures. After the feasibility of treatment and the initial evaluation of treatment performance has been demonstrated, performance must be verified using authentic samples of the candidate waste stream.« less

Role of radiative-convective feedbacks in tropical cyclogenesis in rotating radiative-convective equilibrium simulations

NASA Astrophysics Data System (ADS)

Wing, A. A.; Camargo, S. J.; Sobel, A. H.

2015-12-01

"Self-aggregation" is a mode of convective organization found in idealized numerical simulations, in which there is a spontaneous transition from randomly distributed to organized convection despite homogeneous boundary conditions. Self-aggregation has primarily been studied in a non-rotating framework, but it has been hypothesized to be important to tropical cyclogenesis. In numerical simulations of tropical cyclones, a broad vortex or saturated column is often used to initialize the circulation. Here, we instead allow a circulation to develop spontaneously from a homogeneous environment in 3-d cloud-resolving simulations of radiative-convective equilibrium in a rotating framework, with interactive radiation and surface fluxes and fixed sea surface temperature. The goals of this study are two-fold: to study tropical cyclogenesis in an unperturbed environment free from the influence of a prescribed initial vortex or external disturbances, and to compare cyclogenesis to non-rotating self-aggregation. We quantify the feedbacks leading to tropical cyclogenesis using a variance budget equation for the vertically integrated frozen moist static energy. In the initial development of a broad circulation, the feedback processes are similar to the initial phase of non-rotating aggregation. Sensitivity tests in which the degree of interactive radiation is modified are also performed to determine the extent to which the radiative feedbacks that are essential to non-rotating self-aggregation are important for tropical cyclogenesis. Finally, we examine the evolution of the rotational and divergent flow, to determine the point at which rotation becomes important and the cyclogenesis process begins to differ from non-rotating aggregation.

Binary neutron star merger simulations with different initial orbital frequency and equation of state

NASA Astrophysics Data System (ADS)

Maione, F.; De Pietri, R.; Feo, A.; Löffler, F.

2016-09-01

We present results from three-dimensional general relativistic simulations of binary neutron star coalescences and mergers using public codes. We considered equal mass models where the baryon mass of the two neutron stars is 1.4{M}⊙ , described by four different equations of state (EOS) for the cold nuclear matter (APR4, SLy, H4, and MS1; all parametrized as piecewise polytropes). We started the simulations from four different initial interbinary distances (40,44.3,50, and 60 km), including up to the last 16 orbits before merger. That allows us to show the effects on the gravitational wave (GW) phase evolution, radiated energy and angular momentum due to: the use of different EOS, the orbital eccentricity present in the initial data and the initial separation (in the simulation) between the two stars. Our results show that eccentricity has a major role in the discrepancy between numerical and analytical waveforms until the very last few orbits, where ‘tidal’ effects and missing high-order post-Newtonian coefficients also play a significant role. We test different methods for extrapolating the GW signal extracted at finite radii to null infinity. We show that an effective procedure for integrating the Newman-Penrose {\\psi }4 signal to obtain the GW strain h is to apply a simple high-pass digital filter to h after a time domain integration, where only the two physical motivated integration constants are introduced. That should be preferred to the more common procedures of introducing additional integration constants, integrating in the frequency domain or filtering {\\psi }4 before integration.

Reducing orbital eccentricity of precessing black-hole binaries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buonanno, Alessandra; Taracchini, Andrea; Kidder, Lawrence E.

2011-05-15

Building initial conditions for generic binary black-hole evolutions which are not affected by initial spurious eccentricity remains a challenge for numerical-relativity simulations. This problem can be overcome by applying an eccentricity-removal procedure which consists of evolving the binary black hole for a couple of orbits, estimating the resulting eccentricity, and then restarting the simulation with corrected initial conditions. The presence of spins can complicate this procedure. As predicted by post-Newtonian theory, spin-spin interactions and precession prevent the binary from moving along an adiabatic sequence of spherical orbits, inducing oscillations in the radial separation and in the orbital frequency. For single-spinmore » binary black holes these oscillations are a direct consequence of monopole-quadrupole interactions. However, spin-induced oscillations occur at approximately twice the orbital frequency, and therefore can be distinguished and disentangled from the initial spurious eccentricity which occurs at approximately the orbital frequency. Taking this into account, we develop a new eccentricity-removal procedure based on the derivative of the orbital frequency and find that it is rather successful in reducing the eccentricity measured in the orbital frequency to values less than 10{sup -4} when moderate spins are present. We test this new procedure using numerical-relativity simulations of binary black holes with mass ratios 1.5 and 3, spin magnitude 0.5, and various spin orientations. The numerical simulations exhibit spin-induced oscillations in the dynamics at approximately twice the orbital frequency. Oscillations of similar frequency are also visible in the gravitational-wave phase and frequency of the dominant l=2, m=2 mode.« less

Driving simulator and neuropsychological [corrected] testing in OSAS before and under CPAP therapy.

PubMed

Orth, M; Duchna, H-W; Leidag, M; Widdig, W; Rasche, K; Bauer, T T; Walther, J W; de Zeeuw, J; Malin, J-P; Schultze-Werninghaus, G; Kotterba, S

2005-11-01

Patients with obstructive sleep apnoea syndrome (OSAS) have an increased car accident rate. Investigations on accident frequency are based on case history, insurance reports and driving simulator studies. The present study combines neuropsychological testing of different attention aspects engaged in driving a car and driving simulation to evaluate a suitable instrument for assessing therapeutic effects of continuous positive airway pressure (CPAP). Driving simulator investigation and neuropsychological testing of alertness, vigilance and divided attention were performed in 31 patients with polysomnographically confirmed OSAS (apnoea-hypopnoea index 24.8+/-21.5.h(-1)) before, and 2 and 42 days after initiation of CPAP. Divided attention and alertness improved significantly during CPAP, whereas vigilance remained unchanged. However, accident frequency (OSAS before therapy: 2.7+/-2.0; 2 days after CPAP: 1.5+/-1.4; 42 days after CPAP: 0.9+/-1.3) and frequency of concentration faults (OSAS before therapy: 12.4+/-5.1; 2 days after CPAP: 6.5+/-3.9; 42 days after CPAP: 4.9+/-3.3) decreased in the simulated driving situation after 2 and 42 days of therapy. There was no relation between accident frequency, concentration faults and daytime sleepiness, as measured by the Epworth Sleepiness Scale, and polysomnographic or neuropsychological findings, respectively. In conclusion, the present results suggest that driving simulation is a possible benchmark parameter of driving performance in obstructive sleep apnoea syndrome patients.

Scale Refinement and Initial Evaluation of a Behavioral Health Function Measurement Tool for Work Disability Evaluation

PubMed Central

Marfeo, Elizabeth E.; Ni, Pengsheng; Bogusz, Kara; Meterko, Mark; McDonough, Christine M.; Chan, Leighton; Rasch, Elizabeth K.; Brandt, Diane E.; Jette, Alan M.

2014-01-01

Objectives To use item response theory (IRT) data simulations to construct and perform initial psychometric testing of a newly developed instrument, the Social Security Administration Behavioral Health Function (SSA-BH) instrument, that aims to assess behavioral health functioning relevant to the context of work. Design Cross-sectional survey followed by item response theory (IRT) calibration data simulations Setting Community Participants A sample of individuals applying for SSA disability benefits, claimants (N=1015), and a normative comparative sample of US adults (N=1000) Interventions None. Main Outcome Measure Social Security Administration Behavioral Health Function (SSA-BH) measurement instrument Results Item response theory analyses supported the unidimensionality of four SSA-BH scales: Mood and Emotions (35 items), Self-Efficacy (23 items), Social Interactions (6 items), and Behavioral Control (15 items). All SSA-BH scales demonstrated strong psychometric properties including reliability, accuracy, and breadth of coverage. High correlations of the simulated 5- or 10- item CATs with the full item bank indicated robust ability of the CAT approach to comprehensively characterize behavioral health function along four distinct dimensions. Conclusions Initial testing and evaluation of the SSA-BH instrument demonstrated good accuracy, reliability, and content coverage along all four scales. Behavioral function profiles of SSA claimants were generated and compared to age and sex matched norms along four scales: Mood and Emotions, Behavioral Control, Social Interactions, and Self-Efficacy. Utilizing the CAT based approach offers the ability to collect standardized, comprehensive functional information about claimants in an efficient way, which may prove useful in the context of the SSA’s work disability programs. PMID:23542404

Ares I-X Upper Stage Simulator Structural Analyses Supporting the NESC Critical Initial Flaw Size Assessment

NASA Technical Reports Server (NTRS)

Knight, Norman F., Jr.; Phillips, Dawn R.; Raju, Ivatury S.

2008-01-01

The structural analyses described in the present report were performed in support of the NASA Engineering and Safety Center (NESC) Critical Initial Flaw Size (CIFS) assessment for the ARES I-X Upper Stage Simulator (USS) common shell segment. The structural analysis effort for the NESC assessment had three thrusts: shell buckling analyses, detailed stress analyses of the single-bolt joint test; and stress analyses of two-segment 10 degree-wedge models for the peak axial tensile running load. Elasto-plastic, large-deformation simulations were performed. Stress analysis results indicated that the stress levels were well below the material yield stress for the bounding axial tensile design load. This report also summarizes the analyses and results from parametric studies on modeling the shell-to-gusset weld, flange-surface mismatch, bolt preload, and washer-bearing-surface modeling. These analyses models were used to generate the stress levels specified for the fatigue crack growth assessment using the design load with a factor of safety.

Objective Motion Cueing Criteria Investigation Based on Three Flight Tasks

NASA Technical Reports Server (NTRS)

Zaal, Petrus M. T.; Schroeder, Jeffery A.; Chung, William W.

2015-01-01

This paper intends to help establish fidelity criteria to accompany the simulator motion system diagnostic test specified by the International Civil Aviation Organization. Twelve air- line transport pilots flew three tasks in the NASA Vertical Motion Simulator under four different motion conditions. The experiment used three different hexapod motion configurations, each with a different tradeoff between motion filter gain and break frequency, and one large motion configuration that utilized as much of the simulator's motion space as possible. The motion condition significantly affected: 1) pilot motion fidelity ratings, and sink rate and lateral deviation at touchdown for the approach and landing task, 2) pilot motion fidelity ratings, roll deviations, maximum pitch rate, and number of stick shaker activations in the stall task, and 3) heading deviation after an engine failure in the takeoff task. Significant differences in pilot-vehicle performance were used to define initial objective motion cueing criteria boundaries. These initial fidelity boundaries show promise but need refinement.

Gemini Simulator and Neil Armstrong

NASA Image and Video Library

1963-11-06

Astronaut Neil Armstrong (left) was one of 14 astronauts, 8 NASA test pilots, and 2 McDonnell test pilots who took part in simulator studies. Armstrong was the first astronaut to participate (November 6, 1963). A.W. Vogeley described the simulator in his paper "Discussion of Existing and Planned Simulators For Space Research," "Many of the astronauts have flown this simulator in support of the Gemini studies and they, without exception, appreciated the realism of the visual scene. The simulator has also been used in the development of pilot techniques to handle certain jet malfunctions in order that aborts could be avoided. In these situations large attitude changes are sometimes necessary and the false motion cues that were generated due to earth gravity were somewhat objectionable; however, the pilots were readily able to overlook these false motion cues in favor of the visual realism." Roy F. Brissenden, noted in his paper "Initial Operations with Langley's Rendezvous Docking Facility," "The basic Gemini control studies developed the necessary techniques and demonstrated the ability of human pilots to perform final space docking with the specified Gemini-Agena systems using only visual references. ... Results... showed that trained astronauts can effect the docking with direct acceleration control and even with jet malfunctions as long as good visual conditions exist.... Probably more important than data results was the early confidence that the astronauts themselves gained in their ability to perform the maneuver in the ultimate flight mission." Francis B. Smith, noted in his paper "Simulators for Manned Space Research," "Some major areas of interest in these flights were fuel requirements, docking accuracies, the development of visual aids to assist alignment of the vehicles, and investigation of alternate control techniques with partial failure modes. However, the familiarization and confidence developed by the astronaut through flying and safely docking the simulator during these tests was one of the major contributions. For example, it was found that fuel used in docking from 200 feet typically dropped from about 20 pounds to 7 pounds after an astronaut had made a few training flights." -- Published in Barton C. Hacker and James M. Grimwood, On the Shoulders of Titans: A History of Project Gemini, NASA SP-4203; A.W. Vogeley, "Discussion of Existing and Planned Simulators For Space Research," Paper presented at the Conference on the Role of Simulation in Space Technology, August 17-21, 1964; Roy F. Brissenden, "Initial Operations with Langley's Rendezvous Docking Facility," Langley Working Paper, LWP-21, 1964; Francis B. Smith, "Simulators for Manned Space Research," Paper presented at the 1966 IEEE International convention, March 21-25, 1966.

OPM: The Open Porous Media Initiative

NASA Astrophysics Data System (ADS)

Flemisch, B.; Flornes, K. M.; Lie, K.; Rasmussen, A.

2011-12-01

The principal objective of the Open Porous Media (OPM) initiative is to develop a simulation suite that is capable of modeling industrially and scientifically relevant flow and transport processes in porous media and bridge the gap between the different application areas of porous media modeling, including reservoir mechanics, CO2 sequestration, biological systems, and product development of engineered media. The OPM initiative will provide a long-lasting, efficient, and well-maintained open-source software for flow and transport in porous media built on modern software principles. The suite is released under the GNU General Public License (GPL). Our motivation is to provide a means to unite industry and public research on simulation of flow and transport in porous media. For academic users, we seek to provide a software infrastructure that facilitates testing of new ideas on models with industry-standard complexity, while at the same time giving the researcher control over discretization and solvers. Similarly, we aim to accelerate the technology transfer from academic institutions to professional companies by making new research results available as free software of professional standard. The OPM initiative is currently supported by six research groups in Norway and Germany and funded by existing grants from public research agencies as well as from Statoil Petroleum and Total E&P Norge. However, a full-scale development of the OPM initiative requires substantially more funding and involvement of more research groups and potential end users. In this talk, we will provide an overview of the current activities in the OPM initiative. Special emphasis will be given to the demonstration of the synergies achieved by combining the strengths of individual open-source software components. In particular, a new fully implicit solver developed within the DUNE-based simulator DuMux could be enhanced by the ability to read industry-standard Eclipse input files and to run on grids given in corner-point format. Examples taken from the SPE comparative solution projects and CO2 sequestration benchmarks illustrate the current capabilities of the simulation suite.

Study of the water transportation characteristics of marsh saline soil in the Yellow River Delta.

PubMed

He, Fuhong; Pan, Yinghua; Tan, Lili; Zhang, Zhenhua; Li, Peng; Liu, Jia; Ji, Shuxin; Qin, Zhaohua; Shao, Hongbo; Song, Xueyan

2017-01-01

One-dimensional soil column water infiltration and capillary adsorption water tests were conducted in the laboratory to study the water transportation characteristics of marsh saline soil in the Yellow River Delta, providing a theoretical basis for the improvement, utilization and conservation of marsh saline soil. The results indicated the following: (1) For soils with different vegetation covers, the cumulative infiltration capacity increased with the depth of the soil layers. The initial infiltration rate of soils covered by Suaeda and Tamarix chinensis increased with depth of the soil layers, but that of bare soil decreased with soil depth. (2) The initial rate of capillary rise of soils with different vegetation covers showed an increasing trend from the surface toward the deeper layers, but this pattern with respect to soil depth was relatively weak. (3) The initial rates of capillary rise were lower than the initial infiltration rates, but infiltration rate decreased more rapidly than capillary water adsorption rate. (4) The two-parameter Kostiakov model can very well-simulate the changes in the infiltration and capillary rise rates of wetland saline soil. The model simulated the capillary rise rate better than it simulated the infiltration rate. (5) There were strong linear relationships between accumulative infiltration capacity, wetting front, accumulative capillary adsorbed water volume and capillary height. Copyright © 2016 Elsevier B.V. All rights reserved.

Joint numerical study of the 2011 Tohoku-Oki tsunami: comparative propagation simulations and high resolution coastal models

NASA Astrophysics Data System (ADS)

Loevenbruck, Anne; Arpaia, Luca; Ata, Riadh; Gailler, Audrey; Hayashi, Yutaka; Hébert, Hélène; Heinrich, Philippe; Le Gal, Marine; Lemoine, Anne; Le Roy, Sylvestre; Marcer, Richard; Pedreros, Rodrigo; Pons, Kevin; Ricchiuto, Mario; Violeau, Damien

2017-04-01

This study is part of the joint actions carried out within TANDEM (Tsunamis in northern AtlaNtic: Definition of Effects by Modeling). This French project, mainly dedicated to the appraisal of coastal effects due to tsunami waves on the French coastlines, was initiated after the catastrophic 2011 Tohoku-Oki tsunami. This event, which tragically struck Japan, drew the attention to the importance of tsunami risk assessment, in particular when nuclear facilities are involved. As a contribution to this challenging task, the TANDEM partners intend to provide guidance for the French Atlantic area based on numerical simulation. One of the identified objectives consists in designing, adapting and validating simulation codes for tsunami hazard assessment. Besides an integral benchmarking workpackage, the outstanding database of the 2011 event offers the TANDEM partners the opportunity to test their numerical tools with a real case. As a prerequisite, among the numerous published seismic source models arisen from the inversion of the various available records, a couple of coseismic slip distributions have been selected to provide common initial input parameters for the tsunami computations. After possible adaptations or specific developments, the different codes are employed to simulate the Tohoku-Oki tsunami from its source to the northeast Japanese coastline. The results are tested against the numerous tsunami measurements and, when relevant, comparisons of the different codes are carried out. First, the results related to the oceanic propagation phase are compared with the offshore records. Then, the modeled coastal impacts are tested against the onshore data. Flooding at a regional scale is considered, but high resolution simulations are also performed with some of the codes. They allow examining in detail the runup amplitudes and timing, as well as the complexity of the tsunami interaction with the coastal structures. The work is supported by the Tandem project in the frame of French PIA grant ANR-11-RSNR-00023.

Designing Scenarios for Controller-in-the-Loop Air Traffic Simulations

NASA Technical Reports Server (NTRS)

Kupfer, Michael; Mercer, Joey S.; Cabrall, Christopher; Callantine, Todd

2013-01-01

Well prepared traffic scenarios contribute greatly to the success of controller-in-the-loop simulations. This paper describes each stage in the design process of realistic scenarios based on real-world traffic, to be used in the Airspace Operations Laboratory for simulations within the Air Traffic Management Technology Demonstration 1 effort. The steps from the initial analysis of real-world traffic, to the editing of individual aircraft records in the scenario file, until the final testing of the scenarios before the simulation conduct, are all described. The iterative nature of the design process and the various efforts necessary to reach the required fidelity, as well as the applied design strategies, challenges, and tools used during this process are also discussed.

Numerical Simulation of Delamination Growth in Composite Materials

NASA Technical Reports Server (NTRS)

Camanho, P. P.; Davila, C. G.; Ambur, D. R.

2001-01-01

The use of decohesion elements for the simulation of delamination in composite materials is reviewed. The test methods available to measure the interfacial fracture toughness used in the formulation of decohesion elements are described initially. After a brief presentation of the virtual crack closure technique, the technique most widely used to simulate delamination growth, the formulation of interfacial decohesion elements is described. Problems related with decohesion element constitutive equations, mixed-mode crack growth, element numerical integration and solution procedures are discussed. Based on these investigations, it is concluded that the use of interfacial decohesion elements is a promising technique that avoids the need for a pre-existing crack and pre-defined crack paths, and that these elements can be used to simulate both delamination onset and growth.

Detailed Modeling of Distillation Technologies for Closed-Loop Water Recovery Systems

NASA Technical Reports Server (NTRS)

Allada, Rama Kumar; Lange, Kevin E.; Anderson, Molly S.

2011-01-01

Detailed chemical process simulations are a useful tool in designing and optimizing complex systems and architectures for human life support. Dynamic and steady-state models of these systems help contrast the interactions of various operating parameters and hardware designs, which become extremely useful in trade-study analyses. NASA?s Exploration Life Support technology development project recently made use of such models to compliment a series of tests on different waste water distillation systems. This paper presents efforts to develop chemical process simulations for three technologies: the Cascade Distillation System (CDS), the Vapor Compression Distillation (VCD) system and the Wiped-Film Rotating Disk (WFRD) using the Aspen Custom Modeler and Aspen Plus process simulation tools. The paper discusses system design, modeling details, and modeling results for each technology and presents some comparisons between the model results and recent test data. Following these initial comparisons, some general conclusions and forward work are discussed.

Integrated Test Facility (ITF)

NASA Technical Reports Server (NTRS)

1992-01-01

The NASA-Dryden Integrated Test Facility (ITF), also known as the Walter C. Williams Research Aircraft Integration Facility (RAIF), provides an environment for conducting efficient and thorough testing of advanced, highly integrated research aircraft. Flight test confidence is greatly enhanced by the ability to qualify interactive aircraft systems in a controlled environment. In the ITF, each element of a flight vehicle can be regulated and monitored in real time as it interacts with the rest of the aircraft systems. Testing in the ITF is accomplished through automated techniques in which the research aircraft is interfaced to a high-fidelity real-time simulation. Electric and hydraulic power are also supplied, allowing all systems except the engines to function as if in flight. The testing process is controlled by an engineering workstation that sets up initial conditions for a test, initiates the test run, monitors its progress, and archives the data generated. The workstation is also capable of analyzing results of individual tests, comparing results of multiple tests, and producing reports. The computers used in the automated aircraft testing process are also capable of operating in a stand-alone mode with a simulation cockpit, complete with its own instruments and controls. Control law development and modification, aerodynamic, propulsion, guidance model qualification, and flight planning -- functions traditionally associated with real-time simulation -- can all be performed in this manner. The Remotely Augmented Vehicles (RAV) function, now located in the ITF, is a mainstay in the research techniques employed at Dryden. This function is used for tests that are too dangerous for direct human involvement or for which computational capacity does not exist onboard a research aircraft. RAV provides the researcher with a ground-based computer that is radio linked to the test aircraft during actual flight. The Ground Vibration Testing (GVT) system, formerly housed in the Thermostructural Laboratory, now also resides in the ITF. In preparing a research aircraft for flight testing, it is vital to measure its structural frequencies and mode shapes and compare results to the models used in design analysis. The final function performed in the ITF is routine aircraft maintenance. This includes preflight and post-flight instrumentation checks and the servicing of hydraulics, avionics, and engines necessary on any research aircraft. Aircraft are not merely moved to the ITF for automated testing purposes but are housed there throughout their flight test programs.

Integrated Test Facility (ITF)

NASA Technical Reports Server (NTRS)

1991-01-01

The NASA-Dryden Integrated Test Facility (ITF), also known as the Walter C. Williams Research Aircraft Integration Facility (RAIF), provides an environment for conducting efficient and thorough testing of advanced, highly integrated research aircraft. Flight test confidence is greatly enhanced by the ability to qualify interactive aircraft systems in a controlled environment. In the ITF, each element of a flight vehicle can be regulated and monitored in real time as it interacts with the rest of the aircraft systems. Testing in the ITF is accomplished through automated techniques in which the research aircraft is interfaced to a high-fidelity real-time simulation. Electric and hydraulic power are also supplied, allowing all systems except the engines to function as if in flight. The testing process is controlled by an engineering workstation that sets up initial conditions for a test, initiates the test run, monitors its progress, and archives the data generated. The workstation is also capable of analyzing results of individual tests, comparing results of multiple tests, and producing reports. The computers used in the automated aircraft testing process are also capable of operating in a stand-alone mode with a simulation cockpit, complete with its own instruments and controls. Control law development and modification, aerodynamic, propulsion, guidance model qualification, and flight planning -- functions traditionally associated with real-time simulation -- can all be performed in this manner. The Remotely Augmented Vehicles (RAV) function, now located in the ITF, is a mainstay in the research techniques employed at Dryden. This function is used for tests that are too dangerous for direct human involvement or for which computational capacity does not exist onboard a research aircraft. RAV provides the researcher with a ground-based computer that is radio linked to the test aircraft during actual flight. The Ground Vibration Testing (GVT) system, formerly housed in the Thermostructural Laboratory, now also resides in the ITF. In preparing a research aircraft for flight testing, it is vital to measure its structural frequencies and mode shapes and compare results to the models used in design analysis. The final function performed in the ITF is routine aircraft maintenance. This includes preflight and post-flight instrumentation checks and the servicing of hydraulics, avionics, and engines necessary on any research aircraft. Aircraft are not merely moved to the ITF for automated testing purposes but are housed there throughout their flight test programs.

First results from the spectral DCT trigger implemented in the Cyclone V Front-End Board used for a detection of very inclined showers in the Pierre Auger surface detector Engineering Array

DOE Office of Scientific and Technical Information (OSTI.GOV)

Szadkowski, Zbigniew

2015-07-01

The paper presents the first results from the trigger based on the Discrete Cosine Transform (DCT) operating in the new Front-End Boards with Cyclone V FPGA deployed in 8 test surface detectors in the Pierre Auger Engineering Array. The patterns of the ADC traces generated by very inclined showers were obtained from the Auger database and from the CORSIKA simulation package supported next by Offline reconstruction Auger platform which gives a predicted digitized signal profiles. Simulations for many variants of the initial angle of shower, initialization depth in the atmosphere, type of particle and its initial energy gave a boundarymore » of the DCT coefficients used next for the on-line pattern recognition in the FPGA. Preliminary results have proven a right approach. We registered several showers triggered by the DCT for 120 MSps and 160 MSps. (authors)« less

Effect of traffic density on drivers' lane change and overtaking maneuvers in freeway situation - A driving simulator based study.

PubMed

Yang, Liu; Li, Xiaomeng; Guan, Wei; Zhang, H Michael; Fan, Lingling

2018-05-14

The aim of this study is to examine the effect of traffic density on drivers' lane change and overtaking maneuvers. The differences between drivers' left and right lane-changing/overtaking maneuvers were also investigated. A driving simulator experiment was conducted and 24 participants took part in this experiment. Based on the driving simulation data, lane change frequency, time duration, average speed and acceleration were extracted as key variables of lane change maneuvers; overtaking frequency, overtaking duration, initial overtaking distance and headway, instantaneous speed and acceleration before overtaking were analyzed as the key overtaking variables. One-way repeated measures ANOVA, Friedman test and Wilcoxon signed-rank test were adopted for hypothesis tests with significance level of 0.05. Further pairwise comparisons were performed with a Bonferroni correction for multiple comparisons. Some significant differences in lane change and overtake behaviors were observed among different traffic densities: 1) both lane change and overtaking frequencies significantly increase with traffic density; 2) the average lane change acceleration and instantaneous overtaking acceleration significantly increase with traffic density; 3) as the traffic density increases, the initial overtaking distance and headway decrease. As for the effect of the directions of maneuvers: 1) the time duration of lane change and overtaking from right side was significantly shorter than that from left side; 2) the right initial overtaking distance/headway was smaller than that of left side; 3) the right instantaneous overtaking acceleration was significantly higher than the left instantaneous acceleration. The results showed that as traffic density increases, drivers' intention for lane change and overtaking is enhanced. Both initial overtaking distance and headway decrease with traffic density, which might influence road safety. In addition, drivers do not show a preference on the directions of lane change or overtaking according to the frequency. However, drivers tend to be more decisive and reckless when conducting the right overtaking because of a smaller distance/headway before overtaking, higher instantaneous acceleration and also a more restricted field of view compared with left overtaking.

Teaching medical students a clinical approach to altered mental status: simulation enhances traditional curriculum

PubMed Central

Sperling, Jeremy D.; Clark, Sunday; Kang, Yoon

2013-01-01

Introduction Simulation-based medical education (SBME) is increasingly being utilized for teaching clinical skills in undergraduate medical education. Studies have evaluated the impact of adding SBME to third- and fourth-year curriculum; however, very little research has assessed its efficacy for teaching clinical skills in pre-clerkship coursework. To measure the impact of a simulation exercise during a pre-clinical curriculum, a simulation session was added to a pre-clerkship course at our medical school where the clinical approach to altered mental status (AMS) is traditionally taught using a lecture and an interactive case-based session in a small group format. The objective was to measure simulation's impact on students’ knowledge acquisition, comfort, and perceived competence with regards to the AMS patient. Methods AMS simulation exercises were added to the lecture and small group case sessions in June 2010 and 2011. Simulation sessions consisted of two clinical cases using a high-fidelity full-body simulator followed by a faculty debriefing after each case. Student participation in a simulation session was voluntary. Students who did and did not participate in a simulation session completed a post-test to assess knowledge and a survey to understand comfort and perceived competence in their approach to AMS. Results A total of 154 students completed the post-test and survey and 65 (42%) attended a simulation session. Post-test scores were higher in students who attended a simulation session compared to those who did not (p<0.001). Students who participated in a simulation session were more comfortable in their overall approach to treating AMS patients (p=0.05). They were also more likely to state that they could articulate a differential diagnosis (p=0.03), know what initial diagnostic tests are needed (p=0.01), and understand what interventions are useful in the first few minutes (p=0.003). Students who participated in a simulation session were more likely to find the overall AMS curriculum useful (p<0.001). Conclusion Students who participated in a simulation exercise performed better on a knowledge-based test and reported increased comfort and perceived competence in their clinical approach to AMS. SBME shows significant promise for teaching clinical skills to medical students during pre-clinical curriculum. PMID:23561054

Sensitivity of a Simulated Derecho Event to Model Initial Conditions

NASA Astrophysics Data System (ADS)

Wang, Wei

2014-05-01

Since 2003, the MMM division at NCAR has been experimenting cloud-permitting scale weather forecasting using Weather Research and Forecasting (WRF) model. Over the years, we've tested different model physics, and tried different initial and boundary conditions. Not surprisingly, we found that the model's forecasts are more sensitive to the initial conditions than model physics. In 2012 real-time experiment, WRF-DART (Data Assimilation Research Testbed) at 15 km was employed to produce initial conditions for twice-a-day forecast at 3 km. On June 29, this forecast system captured one of the most destructive derecho event on record. In this presentation, we will examine forecast sensitivity to different model initial conditions, and try to understand the important features that may contribute to the success of the forecast.

A Novel Mobile Testing Equipment for Rock Cuttability Assessment: Vertical Rock Cutting Rig (VRCR)

NASA Astrophysics Data System (ADS)

Yasar, Serdar; Yilmaz, Ali Osman

2017-04-01

In this study, a new mobile rock cutting testing apparatus was designed and produced for rock cuttability assessment called vertical rock cutting rig (VRCR) which was designed specially to fit into hydraulic press testing equipment which are available in almost every rock mechanics laboratory. Rock cutting trials were initiated just after the production of VRCR along with calibration of the measuring load cell with an external load cell to validate the recorded force data. Then, controlled rock cutting tests with both relieved and unrelieved cutting modes were implemented on five different volcanic rock samples with a standard simple-shaped wedge tool. Additionally, core cutting test which is an important approach for roadheader performance prediction was simulated with VRCR. Mini disc cutters and point attack tools were used for execution of experimental trials. Results clearly showed that rock cutting tests were successfully realized and measuring system is delicate to rock strength, cutting depth and other variables. Core cutting test was successfully simulated, and it was also shown that rock cutting tests with mini disc cutters and point attack tools are also successful with VRCR.

Optical Alignment of the JWST ISIM to the OTE Simulator (OSIM): Current Concept and Design Studies

NASA Technical Reports Server (NTRS)

Frey, Bradley J.; Davila, Pamela S.; Marsh, James M.; Ohl, Raymond G.; Sullivan, Joseph

2007-01-01

The James Webb Space Telescope's (JWST) Integrated Science Instrument Module (ISIM) is the scientific payload of the observatory and contai ns four science instruments. During alignment and test of the integrated ISIM (i.e. ISIM + science instruments) at NASA's Goddard Space Fli ght Center (GSFC), the Optical telescope element SIMulator (OSIM) wil l be used to optically stimulate the science instruments to verify their operation and performance. In this paper we present the design of two cryogenic alignment fixtures that will be used to determine and verify the proper alignment of OSIM to ISIM during testing at GSFC. The se fixtures, the Master Alignment Target Fixture (MATF) and the ISIM Alignment Target Fixture (IATF), will provide continuous, 6 degree of freedom feedback to OSIM during initial ambient alignment as well as during cryogenic vacuum testing.

Prediction of fracture initiation in square cup drawing of DP980 using an anisotropic ductile fracture criterion

NASA Astrophysics Data System (ADS)

Park, N.; Huh, H.; Yoon, J. W.

2017-09-01

This paper deals with the prediction of fracture initiation in square cup drawing of DP980 steel sheet with the thickness of 1.2 mm. In an attempt to consider the influence of material anisotropy on the fracture initiation, an uncoupled anisotropic ductile fracture criterion is developed based on the Lou—Huh ductile fracture criterion. Tensile tests are carried out at different loading directions of 0°, 45°, and 90° to the rolling direction of the sheet using various specimen geometries including pure shear, dog-bone, and flat grooved specimens so as to calibrate the parameters of the proposed fracture criterion. Equivalent plastic strain distribution on the specimen surface is computed using Digital Image Correlation (DIC) method until surface crack initiates. The proposed fracture criterion is implemented into the commercial finite element code ABAQUS/Explicit by developing the Vectorized User-defined MATerial (VUMAT) subroutine which features the non-associated flow rule. Simulation results of the square cup drawing test clearly show that the proposed fracture criterion is capable of predicting the fracture initiation with sufficient accuracy considering the material anisotropy.

A Coordinated Initialization Process for the Distributed Space Exploration Simulation (DSES)

NASA Technical Reports Server (NTRS)

Phillips, Robert; Dexter, Dan; Hasan, David; Crues, Edwin Z.

2007-01-01

This document describes the federate initialization process that was developed at the NASA Johnson Space Center with the HIIA Transfer Vehicle Flight Controller Trainer (HTV FCT) simulations and refined in the Distributed Space Exploration Simulation (DSES). These simulations use the High Level Architecture (HLA) IEEE 1516 to provide the communication and coordination between the distributed parts of the simulation. The purpose of the paper is to describe a generic initialization sequence that can be used to create a federate that can: 1. Properly initialize all HLA objects, object instances, interactions, and time management 2. Check for the presence of all federates 3. Coordinate startup with other federates 4. Robustly initialize and share initial object instance data with other federates.

Computer simulation of reservoir depletion and oil flow from the Macondo well following the Deepwater Horizon blowout

USGS Publications Warehouse

Hsieh, Paul

2010-01-01

This report describes the application of a computer model to simulate reservoir depletion and oil flow from the Macondo well following the Deepwater Horizon blowout. Reservoir and fluid data used for model development are based on (1) information released in BP's investigation report of the incident, (2) information provided by BP personnel during meetings in Houston, Texas, and (3) calibration by history matching to shut-in pressures measured in the capping stack during the Well Integrity Test. The model is able to closely match the measured shut-in pressures. In the simulation of the 86-day period from the blowout to shut in, the simulated reservoir pressure at the well face declines from the initial reservoir pressure of 11,850 pounds per square inch (psi) to 9,400 psi. After shut in, the simulated reservoir pressure recovers to a final value of 10,300 psi. The pressure does not recover back to the initial pressure owing to reservoir depletion caused by 86 days of oil discharge. The simulated oil flow rate declines from 63,600 stock tank barrels per day just after the Deepwater Horizon blowout to 52,600 stock tank barrels per day just prior to shut in. The simulated total volume of oil discharged is 4.92 million stock tank barrels. The overall uncertainty in the simulated flow rates and total volume of oil discharged is estimated to be + or - 10 percent.

Walter C. Williams Research Aircraft Integration Facility (RAIF)

NASA Technical Reports Server (NTRS)

1996-01-01

The NASA-Dryden Integrated Test Facility (ITF), also known as the Walter C. Williams Research Aircraft Integration Facility (RAIF), provides an environment for conducting efficient and thorough testing of advanced, highly integrated research aircraft. Flight test confidence is greatly enhanced by the ability to qualify interactive aircraft systems in a controlled environment. In the ITF, each element of a flight vehicle can be regulated and monitored in real time as it interacts with the rest of the aircraft systems. Testing in the ITF is accomplished through automated techniques in which the research aircraft is interfaced to a high-fidelity real-time simulation. Electric and hydraulic power are also supplied, allowing all systems except the engines to function as if in flight. The testing process is controlled by an engineering workstation that sets up initial conditions for a test, initiates the test run, monitors its progress, and archives the data generated. The workstation is also capable of analyzing results of individual tests, comparing results of multiple tests, and producing reports. The computers used in the automated aircraft testing process are also capable of operating in a stand-alone mode with a simulation cockpit, complete with its own instruments and controls. Control law development and modification, aerodynamic, propulsion, guidance model qualification, and flight planning -- functions traditionally associated with real-time simulation -- can all be performed in this manner. The Remotely Augmented Vehicles (RAV) function, now located in the ITF, is a mainstay in the research techniques employed at Dryden. This function is used for tests that are too dangerous for direct human involvement or for which computational capacity does not exist onboard a research aircraft. RAV provides the researcher with a ground-based computer that is radio linked to the test aircraft during actual flight. The Ground Vibration Testing (GVT) system, formerly housed in the Thermostructural Laboratory, now also resides in the ITF. In preparing a research aircraft for flight testing, it is vital to measure its structural frequencies and mode shapes and compare results to the models used in design analysis. The final function performed in the ITF is routine aircraft maintenance. This includes preflight and post-flight instrumentation checks and the servicing of hydraulics, avionics, and engines necessary on any research aircraft. Aircraft are not merely moved to the ITF for automated testing purposes but are housed there throughout their flight test programs.

Interfacing Space Communications and Navigation Network Simulation with Distributed System Integration Laboratories (DSIL)

NASA Technical Reports Server (NTRS)

Jennings, Esther H.; Nguyen, Sam P.; Wang, Shin-Ywan; Woo, Simon S.

2008-01-01

NASA's planned Lunar missions will involve multiple NASA centers where each participating center has a specific role and specialization. In this vision, the Constellation program (CxP)'s Distributed System Integration Laboratories (DSIL) architecture consist of multiple System Integration Labs (SILs), with simulators, emulators, testlabs and control centers interacting with each other over a broadband network to perform test and verification for mission scenarios. To support the end-to-end simulation and emulation effort of NASA' exploration initiatives, different NASA centers are interconnected to participate in distributed simulations. Currently, DSIL has interconnections among the following NASA centers: Johnson Space Center (JSC), Kennedy Space Center (KSC), Marshall Space Flight Center (MSFC) and Jet Propulsion Laboratory (JPL). Through interconnections and interactions among different NASA centers, critical resources and data can be shared, while independent simulations can be performed simultaneously at different NASA locations, to effectively utilize the simulation and emulation capabilities at each center. Furthermore, the development of DSIL can maximally leverage the existing project simulation and testing plans. In this work, we describe the specific role and development activities at JPL for Space Communications and Navigation Network (SCaN) simulator using the Multi-mission Advanced Communications Hybrid Environment for Test and Evaluation (MACHETE) tool to simulate communications effects among mission assets. Using MACHETE, different space network configurations among spacecrafts and ground systems of various parameter sets can be simulated. Data that is necessary for tracking, navigation, and guidance of spacecrafts such as Crew Exploration Vehicle (CEV), Crew Launch Vehicle (CLV), and Lunar Relay Satellite (LRS) and orbit calculation data are disseminated to different NASA centers and updated periodically using the High Level Architecture (HLA). In addition, the performance of DSIL under different traffic loads with different mix of data and priorities are evaluated.

Obstetric team simulation program challenges.

PubMed

Bullough, A S; Wagner, S; Boland, T; Waters, T P; Kim, K; Adams, W

2016-12-01

To describe the challenges associated with the development and assessment of an obstetric emergency team simulation program. The goal was to develop a hybrid, in-situ and high fidelity obstetric emergency team simulation program that incorporated weekly simulation sessions on the labor and delivery unit, and quarterly, education protected sessions in the simulation center. All simulation sessions were video-recorded and reviewed. Labor and delivery unit and simulation center. Medical staff covering labor and delivery, anesthesiology and obstetric residents and obstetric nurses. Assessments included an on-line knowledge multiple-choice questionnaire about the simulation scenarios. This was completed prior to the initial in-situ simulation session and repeated 3 months later, the Clinical Teamwork Scale with inter-rater reliability, participant confidence surveys and subjective participant satisfaction. A web-based curriculum comprising modules on communication skills, team challenges, and team obstetric emergency scenarios was also developed. Over 4 months, only 6 labor and delivery unit in-situ sessions out of a possible 14 sessions were carried out. Four high-fidelity sessions were performed in 2 quarterly education protected meetings in the simulation center. Information technology difficulties led to the completion of only 18 pre/post web-based multiple-choice questionnaires. These test results showed no significant improvement in raw score performance from pre-test to post-test (P=.27). During Clinical Teamwork Scale live and video assessment, trained raters and program faculty were in agreement only 31% and 28% of the time, respectively (Kendall's W=.31, P<.001 and W=.28, P<.001). Participant confidence surveys overall revealed confidence significantly increased (P<.05), from pre-scenario briefing to after post-scenario debriefing. Program feedback indicates a high level of participant satisfaction and improved confidence yet further program refinement is required. Copyright © 2016 Elsevier Inc. All rights reserved.

A Test of Two Theories in the Initial Process Stage of Coalition Formation.

ERIC Educational Resources Information Center

Flaherty, John F.; Arenson, Sidney J.

1978-01-01

Males and females participated in a coalition formation procedure by interacting with a computer program that simulated a pachisi game situation. Female partner preference data supported a weighted probability model of coalition formation over a bargaining theory. Male partner preference data did not support either theory. (Author)

Design, Test, Redesign: Simulation in Technology, Engineering, and Design Education Classrooms

ERIC Educational Resources Information Center

Swinson, Ronnie; Clark, Aaron C.; Ernst, Jeremy V.; Sutton, Kevin

2016-01-01

Today's engineers, designers, and technologists are often thrust into the role of problem solver, from the initial design phase of a product or process all the way to final development. Many engineers in manufacturing environments are tasked with solving problems and continuously improving processes to enhance company profitability, efficiency,…

Stability Analysis of the Planetary System Orbiting Upsilon Andromedae. 2; Simulations Using New Lick Observatory Fits

NASA Technical Reports Server (NTRS)

Lissauer, Jack J.; Rivera, Eugenio J.; DeVincenzi, Donald (Technical Monitor)

2001-01-01

We present results of long-term numerical orbital integrations designed to test the stability of the three-planet system orbiting upsilon Andromedae and short-term integrations to test whether mutual perturbations among the planets can be used to determine planetary masses. Our initial conditions are based on recent fits to the radial velocity data obtained by the planet search group at Lick Observatory. The new fits result in significantly more stable systems than did the initially announced planetary parameters. Our integrations using the 2000 February parameters show that if the system is nearly planar, then it is stable for at least 100 Myr for m(sub f) = 1/sin i less than or = 4. In some stable systems, the eccentricity of the inner planet experiences large oscillations. The relative periastra of the outer two planets' orbits librate about 0 deg. in most of the stable systems; if future observations imply that the periastron longitudes of these planets are very closely aligned at the present epoch, dynamical simulations may provide precise estimates for the masses and orbital inclinations of these two planets.

Using 3D Printing (Additive Manufacturing) to Produce Low-Cost Simulation Models for Medical Training.

PubMed

Lichtenberger, John P; Tatum, Peter S; Gada, Satyen; Wyn, Mark; Ho, Vincent B; Liacouras, Peter

2018-03-01

This work describes customized, task-specific simulation models derived from 3D printing in clinical settings and medical professional training programs. Simulation models/task trainers have an array of purposes and desired achievements for the trainee, defining that these are the first step in the production process. After this purpose is defined, computer-aided design and 3D printing (additive manufacturing) are used to create a customized anatomical model. Simulation models then undergo initial in-house testing by medical specialists followed by a larger scale beta testing. Feedback is acquired, via surveys, to validate effectiveness and to guide or determine if any future modifications and/or improvements are necessary. Numerous custom simulation models have been successfully completed with resulting task trainers designed for procedures, including removal of ocular foreign bodies, ultrasound-guided joint injections, nerve block injections, and various suturing and reconstruction procedures. These task trainers have been frequently utilized in the delivery of simulation-based training with increasing demand. 3D printing has been integral to the production of limited-quantity, low-cost simulation models across a variety of medical specialties. In general, production cost is a small fraction of a commercial, generic simulation model, if available. These simulation and training models are customized to the educational need and serve an integral role in the education of our military health professionals.

Reconstructing solar magnetic fields from historical observations. II. Testing the surface flux transport model

NASA Astrophysics Data System (ADS)

Virtanen, I. O. I.; Virtanen, I. I.; Pevtsov, A. A.; Yeates, A.; Mursula, K.

2017-07-01

Aims: We aim to use the surface flux transport model to simulate the long-term evolution of the photospheric magnetic field from historical observations. In this work we study the accuracy of the model and its sensitivity to uncertainties in its main parameters and the input data. Methods: We tested the model by running simulations with different values of meridional circulation and supergranular diffusion parameters, and studied how the flux distribution inside active regions and the initial magnetic field affected the simulation. We compared the results to assess how sensitive the simulation is to uncertainties in meridional circulation speed, supergranular diffusion, and input data. We also compared the simulated magnetic field with observations. Results: We find that there is generally good agreement between simulations and observations. Although the model is not capable of replicating fine details of the magnetic field, the long-term evolution of the polar field is very similar in simulations and observations. Simulations typically yield a smoother evolution of polar fields than observations, which often include artificial variations due to observational limitations. We also find that the simulated field is fairly insensitive to uncertainties in model parameters or the input data. Due to the decay term included in the model the effects of the uncertainties are somewhat minor or temporary, lasting typically one solar cycle.

Predicting knee replacement damage in a simulator machine using a computational model with a consistent wear factor.

PubMed

Zhao, Dong; Sakoda, Hideyuki; Sawyer, W Gregory; Banks, Scott A; Fregly, Benjamin J

2008-02-01

Wear of ultrahigh molecular weight polyethylene remains a primary factor limiting the longevity of total knee replacements (TKRs). However, wear testing on a simulator machine is time consuming and expensive, making it impractical for iterative design purposes. The objectives of this paper were first, to evaluate whether a computational model using a wear factor consistent with the TKR material pair can predict accurate TKR damage measured in a simulator machine, and second, to investigate how choice of surface evolution method (fixed or variable step) and material model (linear or nonlinear) affect the prediction. An iterative computational damage model was constructed for a commercial knee implant in an AMTI simulator machine. The damage model combined a dynamic contact model with a surface evolution model to predict how wear plus creep progressively alter tibial insert geometry over multiple simulations. The computational framework was validated by predicting wear in a cylinder-on-plate system for which an analytical solution was derived. The implant damage model was evaluated for 5 million cycles of simulated gait using damage measurements made on the same implant in an AMTI machine. Using a pin-on-plate wear factor for the same material pair as the implant, the model predicted tibial insert wear volume to within 2% error and damage depths and areas to within 18% and 10% error, respectively. Choice of material model had little influence, while inclusion of surface evolution affected damage depth and area but not wear volume predictions. Surface evolution method was important only during the initial cycles, where variable step was needed to capture rapid geometry changes due to the creep. Overall, our results indicate that accurate TKR damage predictions can be made with a computational model using a constant wear factor obtained from pin-on-plate tests for the same material pair, and furthermore, that surface evolution method matters only during the initial "break in" period of the simulation.

Impact tests on fibrous composite sandwich structures

NASA Technical Reports Server (NTRS)

Rhodes, M. D.

1978-01-01

The effect of low velocity impact on the strength of laminates fabricated from graphite/epoxy and Kevlar 49/epoxy composite materials was studied. The test laminates were loaded statically either in uniaxial tension or compression when impact occurred to evaluate the effect of loading on the initiation of damage and/or failure. Typical aircraft service conditions such as runway debris encountered during landing were simulated by impacting 1.27-cm-diameter projectiles normal to the plane of the test laminates at velocities between 5.2 and 48.8 m/s.

Terahertz NDE of Stressed Composite Overwrapped Pressure Vessels - Initial Testing

NASA Technical Reports Server (NTRS)

Madaras, Eric I.; Seebo, Jeffrey P.; Anatasi, Robert F.

2009-01-01

Terahertz radiation nondestructive evaluation was applied to a set of Kevlar composite overwrapped pressure vessel bottles that had undergone a series of thermal and pressure tests to simulate stress rupture effects. The bottles in these nondestructive evaluation tests were bottles that had not ruptured but had survived various times at the elevated load and temperature levels. Some of the bottles showed evidence of minor composite failures. The terahertz radiation did detect visible surface flaws, but did not detect any internal chemical or material degradation of the thin overwraps.

Titanium-Oxygen Reactivity Study

NASA Technical Reports Server (NTRS)

Chafey, J. E.; Scheck, W. G.; Witzell, W. E.

1962-01-01

A program has been conducted at Astronautics to investigate the likelihood of occurrence of the catastrophic oxidation of titanium alloy sheet under conditions which simulate certain cases of accidental failure of the metal while it is in contact with liquid or gaseous oxygen. Three methods of fracturing the metal were used; they consisted of mechanical puncture, tensile fracture of welded joints, and perforation by very high velocity particles. The results of the tests which have been conducted provide further evidence of the reactivity of titanium with liquid and gaseous oxygen. The evidence indicates that the rapid fracturing of titanium sheet while it is in contact with oxygen initiates the catastrophic oxidation reaction. Initiation occurred when the speed of the fracture was some few feet per second, as in both the drop-weight puncture tests and the static tensile fracture tests of welded joints, as well as when the speed was several thousand feet per second, as in the simulated micrometeoroid penetration tests. The slow propagation of a crack, however, did not initiate the reaction. It may logically be concluded that the localized frictional heat of rapid fracture and/or spontaneous oxidation (exothermic) of minute particles emanating from the fracture cause initiation of the reaction. Under conditions of slow fracture, however, the small heat generated may be adequately dissipated and the reaction is not initiated. A portion of the study conducted consisted of investigating various means by which the reaction might be retarded or prevented. Providing a "barrier" at the titanium-oxygen interface consisting of either aluminum metal or a coating of a petroleum base corrosion inhibitor appeared to be only partially effective in retarding the reaction. The accidental puncturing or similar rupturing of thin-walled pressurized oxygen tanks on missiles and space vehicle will usually constitute loss of function, and may sometimes cause their catastrophic destruction by explosive decompression regardless of the type of material used for their construction. In the case of tanks constructed of titanium alloys the added risk is incurred of catastrophic burning of the tanks. In view of this it is recommended that thin-walled tanks constructed of titanium alloys should not be used to contain liquid or gaseous oxygen.

Performance of medical students on a virtual reality simulator for knee arthroscopy: an analysis of learning curves and predictors of performance.

PubMed

Rahm, Stefan; Wieser, Karl; Wicki, Ilhui; Holenstein, Livia; Fucentese, Sandro F; Gerber, Christian

2016-03-25

Ethical concerns for surgical training on patients, limited working hours with fewer cases per trainee and the potential to better select talented persons for arthroscopic surgery raise the interest in simulator training for arthroscopic surgery. It was the purpose of this study to analyze learning curves of novices using a knee arthroscopy simulator and to correlate their performance with potentially predictive factors. Twenty medical students completed visuospatial tests and were then subjected to a simulator training program of eight 30 min sessions. Their test results were quantitatively correlated with their simulator performance at initiation, during and at the end of the program. The mean arthroscopic performance score (z-score in points) at the eight test sessions were 1. -35 (range, -126 to -5) points, 2. -16 (range, -30 to -2), 3. -11 (range, -35 to 4), 4. -3 (range, -16 to 5), 5. -2 (range, -28 to 7), 6. 1 (range, -18 to 8), 7. 2 (range, -9 to 8), 8. 2 (range, -4 to 7). Scores improved significantly from sessions 1 to 2 (p = 0.001), 2 to 3 (p = 0.052) and 3 to 4 (p = 0.001) but not thereafter. None of the investigated parameters predicted performance or development of arthroscopic performance. Novices improve significantly within four 30 min test virtual arthroscopy knee simulator training but not thereafter within the setting studied. No factors, predicting talent or speed and magnitude of improvement of skills could be identified.

Do downscaled general circulation models reliably simulate historical climatic conditions?

USGS Publications Warehouse

Bock, Andrew R.; Hay, Lauren E.; McCabe, Gregory J.; Markstrom, Steven L.; Atkinson, R. Dwight

2018-01-01

The accuracy of statistically downscaled (SD) general circulation model (GCM) simulations of monthly surface climate for historical conditions (1950–2005) was assessed for the conterminous United States (CONUS). The SD monthly precipitation (PPT) and temperature (TAVE) from 95 GCMs from phases 3 and 5 of the Coupled Model Intercomparison Project (CMIP3 and CMIP5) were used as inputs to a monthly water balance model (MWBM). Distributions of MWBM input (PPT and TAVE) and output [runoff (RUN)] variables derived from gridded station data (GSD) and historical SD climate were compared using the Kolmogorov–Smirnov (KS) test For all three variables considered, the KS test results showed that variables simulated using CMIP5 generally are more reliable than those derived from CMIP3, likely due to improvements in PPT simulations. At most locations across the CONUS, the largest differences between GSD and SD PPT and RUN occurred in the lowest part of the distributions (i.e., low-flow RUN and low-magnitude PPT). Results indicate that for the majority of the CONUS, there are downscaled GCMs that can reliably simulate historical climatic conditions. But, in some geographic locations, none of the SD GCMs replicated historical conditions for two of the three variables (PPT and RUN) based on the KS test, with a significance level of 0.05. In these locations, improved GCM simulations of PPT are needed to more reliably estimate components of the hydrologic cycle. Simple metrics and statistical tests, such as those described here, can provide an initial set of criteria to help simplify GCM selection.

Examining System-Wide Impacts of Solar PV Control Systems with a Power Hardware-in-the-Loop Platform

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Tess L.; Fuller, Jason C.; Schneider, Kevin P.

2014-06-08

High penetration levels of distributed solar PV power generation can lead to adverse power quality impacts, such as excessive voltage rise, voltage flicker, and reactive power values that result in unacceptable voltage levels. Advanced inverter control schemes have been developed that have the potential to mitigate many power quality concerns. However, local closed-loop control may lead to unintended behavior in deployed systems as complex interactions can occur between numerous operating devices. To enable the study of the performance of advanced control schemes in a detailed distribution system environment, a test platform has been developed that integrates Power Hardware-in-the-Loop (PHIL) withmore » concurrent time-series electric distribution system simulation. In the test platform, GridLAB-D, a distribution system simulation tool, runs a detailed simulation of a distribution feeder in real-time mode at the Pacific Northwest National Laboratory (PNNL) and supplies power system parameters at a point of common coupling. At the National Renewable Energy Laboratory (NREL), a hardware inverter interacts with grid and PV simulators emulating an operational distribution system. Power output from the inverters is measured and sent to PNNL to update the real-time distribution system simulation. The platform is described and initial test cases are presented. The platform is used to study the system-wide impacts and the interactions of inverter control modes—constant power factor and active Volt/VAr control—when integrated into a simulated IEEE 8500-node test feeder. We demonstrate that this platform is well-suited to the study of advanced inverter controls and their impacts on the power quality of a distribution feeder. Additionally, results are used to validate GridLAB-D simulations of advanced inverter controls.« less

Crack initiation modeling of a directionally-solidified nickel-base superalloy

NASA Astrophysics Data System (ADS)

Gordon, Ali Page

Combustion gas turbine components designed for application in electric power generation equipment are subject to periodic replacement as a result of cracking, damage, and mechanical property degeneration that render them unsafe for continued operation. In view of the significant costs associated with inspecting, servicing, and replacing damaged components, there has been much interest in developing models that not only predict service life, but also estimate the evolved microstructural state of the material. This thesis explains manifestations of microstructural damage mechanisms that facilitate fatigue crack nucleation in a newly-developed directionally-solidified (DS) Ni-base superalloy components exposed to elevated temperatures and high stresses. In this study, models were developed and validated for damage and life prediction using DS GTD-111 as the subject material. This material, proprietary to General Electric Energy, has a chemical composition and grain structure designed to withstand creep damage occurring in the first and second stage blades of gas-powered turbines. The service conditions in these components, which generally exceed 600°C, facilitate the onset of one or more damage mechanisms related to fatigue, creep, or environment. The study was divided into an empirical phase, which consisted of experimentally simulating service conditions in fatigue specimens, and a modeling phase, which entailed numerically simulating the stress-strain response of the material. Experiments have been carried out to simulate a variety of thermal, mechanical, and environmental operating conditions endured by longitudinally (L) and transversely (T) oriented DS GTD-111. Both in-phase and out-of-phase thermo-mechanical fatigue tests were conducted. In some cases, tests in extreme environments/temperatures were needed to isolate one or at most two of the mechanisms causing damage. Microstructural examinations were carried out via SEM and optical microscopy. A continuum crystal plasticity model was used to simulate the material behavior in the L and T orientations. The constitutive model was implemented in ABAQUS and a parameter estimation scheme was developed to obtain the material constants. A physically-based model was developed for correlating crack initiation life based on the experimental life data and predictions are made using the crack initiation model. Assuming a unique relationship between the damage fraction and cycle fraction with respect to cycles to crack initiation for each damage mode, the total crack initiation life has been represented in terms of the individual damage components (fatigue, creep-fatigue, creep, and oxidation-fatigue) observed at the end state of crack initiation.

Quantitative, steady-state properties of Catania's computational model of the operant reserve.

PubMed

Berg, John P; McDowell, J J

2011-05-01

Catania (2005) found that a computational model of the operant reserve (Skinner, 1938) produced realistic behavior in initial, exploratory analyses. Although Catania's operant reserve computational model demonstrated potential to simulate varied behavioral phenomena, the model was not systematically tested. The current project replicated and extended the Catania model, clarified its capabilities through systematic testing, and determined the extent to which it produces behavior corresponding to matching theory. Significant departures from both classic and modern matching theory were found in behavior generated by the model across all conditions. The results suggest that a simple, dynamic operant model of the reflex reserve does not simulate realistic steady state behavior. Copyright © 2011 Elsevier B.V. All rights reserved.

Effect of Shockwave Curvature on Run Distance Observed with a Modified Wedge Test

NASA Astrophysics Data System (ADS)

Lee, Richard; Dorgan, Robert; Sutherland, Gerrit; Benedetta, Ashley; Milby, Christopher

2011-06-01

The effect of wave curvature on shock initiation in PBXN-110 was investigated using a modified wedge test configuration. Various thicknesses of PBXN-110 donor slabs were used to define the shockwave curvature introduced to wedge samples of the same explosive. The donor slabs were initiated with line-wave generators so that the introduced shock would be the same shape, magnitude and duration across the entire input surface of the wedge. The shock parameters were varied for a given donor thickness via different widths of PMMA spacers placed between the donor and the wedge. A framing camera was used to observe where initiation occurred along the face of the wedge. Initiation always occurred at the center of the shock front instead of the sides like that reported by others using a much smaller test format. Results were compared to CTH calculations to indicate if there were effects associated with highly curved shock fronts that could not be adequately predicted. The run distance predicted in CTH for a 50.8 mm thick donor slab (low curvature) compared favorably with experimental results. However, results from thinner donor slabs (higher curvature) indicate a more sensitive behavior than the simulations predicted.

Effect of shockwave curvature on run distance observed with a modified wedge test

NASA Astrophysics Data System (ADS)

Lee, Richard; Dorgan, Robert J.; Sutherland, Gerrit; Benedetta, Ashley; Milby, Christopher

2012-03-01

The effect of wave curvature on shock initiation in PBXN-110 was investigated using a modified wedge test configuration. Various widths of PBXN-110 donor slabs were used to define the shockwave curvature introduced to wedge samples of the same explosive. The donor slabs were initiated with line-wave generators so that the shock from the donor would be the same shape, magnitude and duration across the entire input surface of the wedge. The shock parameters were varied for a given donor with PMMA spacers placed between the donor and the wedge sample. A high-speed electronic framing camera was used to observe where initiation occurred along the face of the wedge. Initiation always occurred at the center of the shock front instead of along the sides like that reported by others using a much smaller test format. Results were compared to CTH calculations to indicate if there were effects associated with highly curved shock fronts that could not be adequately predicted. The run distance predicted in CTH for a 50.8 mm wide donor slab (low curvature) compared favorably with experimental results. However, results from thinner donor slabs (higher curvature) indicate a more sensitive behavior than the simulations predicted.

Microstructural studies on failure mechanisms in thermo-mechanical fatigue of repaired DS R80 and IN 738 Superalloys

NASA Astrophysics Data System (ADS)

Abrokwah, Emmanuel Otchere

Directionally solidified Rene 80 (DS R80) and polycrystalline Inconel 738(IN 738) Superalloys were tested in thermo-mechanical fatigue (TMF) over the temperature range of 500-900°C and plastic strain range from 0.1 to 0.8% using a DSI Gleeble thermal simulator. Thermo-mechanical testing was carried out on the parent material (baseline) in the conventional solution treated and aged condition (STA), as well as gas tungsten arc welded (GTAW) with an IN-738 filler, followed by solution treatment and ageing. Comparison of the baseline alloy microstructure with that of the welded and heat treated alloy showed that varying crack initiation mechanisms, notably oxidation by stress assisted grain boundary oxidation, grain boundary MC carbides fatigue crack initiation, fatigue crack initiation from sample surfaces, crack initiation from weld defects and creep deformation were operating, leading to different “weakest link” and failure initiation points. The observations from this study show that the repaired samples had extra crack initiation sites not present in the baseline, which accounted for their occasional poor fatigue life. These defects include lack of fusion between the weld and the base metal, fusion zone cracking, and heat affected zone microfissures.

On the construction of a direct numerical simulation of a breaking inertia-gravity wave in the upper mesosphere

NASA Astrophysics Data System (ADS)

Fruman, Mark D.; Remmler, Sebastian; Achatz, Ulrich; Hickel, Stefan

2014-10-01

A systematic approach to the direct numerical simulation (DNS) of breaking upper mesospheric inertia-gravity waves of amplitude close to or above the threshold for static instability is presented. Normal mode or singular vector analysis applied in a frame of reference moving with the phase velocity of the wave (in which the wave is a steady solution) is used to determine the most likely scale and structure of the primary instability and to initialize nonlinear "2.5-D" simulations (with three-dimensional velocity and vorticity fields but depending only on two spatial coordinates). Singular vector analysis is then applied to the time-dependent 2.5-D solution to predict the transition of the breaking event to three-dimensional turbulence and to initialize three-dimensional DNS. The careful choice of the computational domain and the relatively low Reynolds numbers, on the order of 25,000, relevant to breaking waves in the upper mesosphere, makes the three-dimensional DNS tractable with present-day computing clusters. Three test cases are presented: a statically unstable low-frequency inertia-gravity wave, a statically and dynamically stable inertia-gravity wave, and a statically unstable high-frequency gravity wave. The three-dimensional DNS are compared to ensembles of 2.5-D simulations. In general, the decay of the wave and generation of turbulence is faster in three dimensions, but the results are otherwise qualitatively and quantitatively similar, suggesting that results of 2.5-D simulations are meaningful if the domain and initial condition are chosen properly.

Feasibility of Conducting J-2X Engine Testing at the Glenn Research Center Plum Brook Station B-2 Facility

NASA Technical Reports Server (NTRS)

Schafer, Charles F.; Cheston, Derrick J.; Worlund, Armis L.; Brown, James R.; Hooper, William G.; Monk, Jan C.; Winstead, Thomas W.

2008-01-01

A trade study of the feasibility of conducting J-2X testing in the Glenn Research Center (GRC) Plum Brook Station (PBS) B-2 facility was initiated in May 2006 with results available in October 2006. The Propulsion Test Integration Group (PTIG) led the study with support from Marshall Space Flight Center (MSFC) and Jacobs Sverdrup Engineering. The primary focus of the trade study was on facility design concepts and their capability to satisfy the J-2X altitude simulation test requirements. The propulsion systems tested in the B-2 facility were in the 30,000-pound (30K) thrust class. The J-2X thrust is approximately 10 times larger. Therefore, concepts significantly different from the current configuration are necessary for the diffuser, spray chamber subsystems, and cooling water. Steam exhaust condensation in the spray chamber is judged to be the key risk consideration relative to acceptable spray chamber pressure. Further assessment via computational fluid dynamics (CFD) and other simulation capabilities (e.g. methodology for anchoring predictions with actual test data and subscale testing to support investigation.

Test Report for MSFC Test No. 83-2: Pressure scaled water impact test of a 12.5 inch diameter model of the Space Shuttle solid rocket booster filament wound case and external TVC PCD

NASA Technical Reports Server (NTRS)

1983-01-01

Water impact tests using a 12.5 inch diameter model representing a 8.56 percent scale of the Space Shuttle Solid Rocket Booster configuration were conducted. The two primary objectives of this SRB scale model water impact test program were: 1. Obtain cavity collapse applied pressure distributions for the 8.56 percent rigid body scale model FWC pressure magnitudes as a function of full-scale initial impact conditions at vertical velocities from 65 to 85 ft/sec, horizontal velocities from 0 to 45 ft/sec, and angles from -10 to +10 degrees. 2. Obtain rigid body applied pressures on the TVC pod and aft skirt internal stiffener rings at initial impact and cavity collapse loading events. In addition, nozzle loads were measured. Full scale vertical velocities of 65 to 85 ft/sec, horizontal velocities of 0 to 45 ft/sec, and impact angles from -10 to +10 degrees simulated.

Hanford Waste End Effector Phase I Test Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berglin, Eric J.; Hatchell, Brian K.; Mount, Jason C.

This test plan describes the Phase 1 testing program of the Hanford Waste End Effector (HWEE) at the Washington River Protection Solutions’ Cold Test Facility (CTF) using a Pacific Northwest National Laboratory (PNNL)-designed testing setup. This effort fulfills the informational needs for initial assessment of the HWEE to support Hanford single-shell tank A-105 retrieval. This task will install the HWEE on a PNNL-designed robotic gantry system at CTF, install and calibrate instrumentation to measure reaction forces and process parameters, prepare and characterize simulant materials, and implement the test program. The tests will involve retrieval of water, sludge, and hardpan simulantsmore » to determine pumping rate, dilution factors, and screen fouling rate.« less

Manual for the Jet Event and Background Simulation Library(JEBSimLib)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heinz, Matthias; Soltz, Ron; Angerami, Aaron

Jets are the collimated streams of particles resulting from hard scattering in the initial state of high-energy collisions. In heavy-ion collisions, jets interact with the quark-gluon plasma (QGP) before freezeout, providing a probe into the internal structure and properties of the QGP. In order to study jets, background must be subtracted from the measured event, potentially introducing a bias. We aim to understand and quantify this subtraction bias. PYTHIA, a library to simulate pure jet events, is used to simulate a model for a signature with one pure jet (a photon) and one quenched jet, where all quenched particle momentamore » are reduced by a user-de ned constant fraction. Background for the event is simulated using multiplicity values generated by the TRENTO initial state model of heavy-ion collisions fed into a thermal model consisting of a 3-dimensional Boltzmann distribution for particle types and momenta. Data from the simulated events is used to train a statistical model, which computes a posterior distribution of the quench factor for a data set. The model was tested rst on pure jet events and then on full events including the background. This model will allow for a quantitative determination of biases induced by various methods of background subtraction.« less

Manual for the Jet Event and Background Simulation Library

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heinz, M.; Soltz, R.; Angerami, A.

Jets are the collimated streams of particles resulting from hard scattering in the initial state of high-energy collisions. In heavy-ion collisions, jets interact with the quark-gluon plasma (QGP) before freezeout, providing a probe into the internal structure and properties of the QGP. In order to study jets, background must be subtracted from the measured event, potentially introducing a bias. We aim to understand and quantify this subtraction bias. PYTHIA, a library to simulate pure jet events, is used to simulate a model for a signature with one pure jet (a photon) and one quenched jet, where all quenched particle momentamore » are reduced by a user-de ned constant fraction. Background for the event is simulated using multiplicity values generated by the TRENTO initial state model of heavy-ion collisions fed into a thermal model consisting of a 3-dimensional Boltzmann distribution for particle types and momenta. Data from the simulated events is used to train a statistical model, which computes a posterior distribution of the quench factor for a data set. The model was tested rst on pure jet events and then on full events including the background. This model will allow for a quantitative determination of biases induced by various methods of background subtraction.« less

Structural Analysis and Test Comparison of a 20-Meter Inflation-Deployed Solar Sail

NASA Technical Reports Server (NTRS)

Sleight, David W.; Mann, Troy; Lichodziejewski, David; Derbes, Billy

2006-01-01

Under the direction of the NASA In-Space Propulsion Technology Office, the team of L Garde, NASA Jet Propulsion Laboratory, Ball Aerospace, and NASA Langley Research Center has been developing a scalable solar sail configuration to address NASA s future space propulsion needs. Prior to a flight experiment of a full-scale solar sail, a comprehensive test program was implemented to advance the technology readiness level of the solar sail design. These tests consisted of solar sail component, subsystem, and sub-scale system ground tests that simulated the aspects of the space environment such as vacuum and thermal conditions. In July 2005, a 20-m four-quadrant solar sail system test article was tested in the NASA Glenn Research Center s Space Power Facility to measure its static and dynamic structural responses. Key to the maturation of solar sail technology is the development of validated finite element analysis (FEA) models that can be used for design and analysis of solar sails. A major objective of the program was to utilize the test data to validate the FEA models simulating the solar sail ground tests. The FEA software, ABAQUS, was used to perform the structural analyses to simulate the ground tests performed on the 20-m solar sail test article. This paper presents the details of the FEA modeling, the structural analyses simulating the ground tests, and a comparison of the pretest and post-test analysis predictions with the ground test results for the 20-m solar sail system test article. The structural responses that are compared in the paper include load-deflection curves and natural frequencies for the beam structural assembly and static shape, natural frequencies, and mode shapes for the solar sail membrane. The analysis predictions were in reasonable agreement with the test data. Factors that precluded better correlation of the analyses and the tests were unmeasured initial conditions in the test set-up.

Interactive Schematic Integration Within the Propellant System Modeling Environment

NASA Technical Reports Server (NTRS)

Coote, David; Ryan, Harry; Burton, Kenneth; McKinney, Lee; Woodman, Don

2012-01-01

Task requirements for rocket propulsion test preparations of the test stand facilities drive the need to model the test facility propellant systems prior to constructing physical modifications. The Propellant System Modeling Environment (PSME) is an initiative designed to enable increased efficiency and expanded capabilities to a broader base of NASA engineers in the use of modeling and simulation (M&S) technologies for rocket propulsion test and launch mission requirements. PSME will enable a wider scope of users to utilize M&S of propulsion test and launch facilities for predictive and post-analysis functionality by offering a clean, easy-to-use, high-performance application environment.

PFLOTRAN Verification: Development of a Testing Suite to Ensure Software Quality

NASA Astrophysics Data System (ADS)

Hammond, G. E.; Frederick, J. M.

2016-12-01

In scientific computing, code verification ensures the reliability and numerical accuracy of a model simulation by comparing the simulation results to experimental data or known analytical solutions. The model is typically defined by a set of partial differential equations with initial and boundary conditions, and verification ensures whether the mathematical model is solved correctly by the software. Code verification is especially important if the software is used to model high-consequence systems which cannot be physically tested in a fully representative environment [Oberkampf and Trucano (2007)]. Justified confidence in a particular computational tool requires clarity in the exercised physics and transparency in its verification process with proper documentation. We present a quality assurance (QA) testing suite developed by Sandia National Laboratories that performs code verification for PFLOTRAN, an open source, massively-parallel subsurface simulator. PFLOTRAN solves systems of generally nonlinear partial differential equations describing multiphase, multicomponent and multiscale reactive flow and transport processes in porous media. PFLOTRAN's QA test suite compares the numerical solutions of benchmark problems in heat and mass transport against known, closed-form, analytical solutions, including documentation of the exercised physical process models implemented in each PFLOTRAN benchmark simulation. The QA test suite development strives to follow the recommendations given by Oberkampf and Trucano (2007), which describes four essential elements in high-quality verification benchmark construction: (1) conceptual description, (2) mathematical description, (3) accuracy assessment, and (4) additional documentation and user information. Several QA tests within the suite will be presented, including details of the benchmark problems and their closed-form analytical solutions, implementation of benchmark problems in PFLOTRAN simulations, and the criteria used to assess PFLOTRAN's performance in the code verification procedure. References Oberkampf, W. L., and T. G. Trucano (2007), Verification and Validation Benchmarks, SAND2007-0853, 67 pgs., Sandia National Laboratories, Albuquerque, NM.

The Influence of Soil Moisture, Coastline Curvature, and Land-Breeze Circulations on Sea-Breeze Initiated Precipitation

NASA Technical Reports Server (NTRS)

Baker, David R.; Lynn, Barry H.; Boone, Aaron; Tao, Wei-Kuo; Simpson, Joanne

2000-01-01

Idealized numerical simulations are performed with a coupled atmosphere/land-surface model to identify the roles of initial soil moisture, coastline curvature, and land breeze circulations on sea breeze initiated precipitation. Data collected on 27 July 1991 during the Convection and Precipitation Electrification Experiment (CAPE) in central Florida are used. The 3D Goddard Cumulus Ensemble (GCE) cloud resolving model is coupled with the Goddard Parameterization for Land-Atmosphere-Cloud Exchange (PLACE) land surface model, thus providing a tool to simulate more realistically land-surface/atmosphere interaction and convective initiation. Eight simulations are conducted with either straight or curved coast-lines, initially homogeneous soil moisture or initially variable soil moisture, and initially homogeneous horizontal winds or initially variable horizontal winds (land breezes). All model simulations capture the diurnal evolution and general distribution of sea-breeze initiated precipitation over central Florida. The distribution of initial soil moisture influences the timing, intensity and location of subsequent precipitation. Soil moisture acts as a moisture source for the atmosphere, increases the connectively available potential energy, and thus preferentially focuses heavy precipitation over existing wet soil. Strong soil moisture-induced mesoscale circulations are not evident in these simulations. Coastline curvature has a major impact on the timing and location of precipitation. Earlier low-level convergence occurs inland of convex coastlines, and subsequent precipitation occurs earlier in simulations with curved coastlines. The presence of initial land breezes alone has little impact on subsequent precipitation. however, simulations with both coastline curvature and initial land breezes produce significantly larger peak rain rates due to nonlinear interactions.

A Unique Computational Algorithm to Simulate Probabilistic Multi-Factor Interaction Model Complex Material Point Behavior

NASA Technical Reports Server (NTRS)

Chamis, Christos C.; Abumeri, Galib H.

2010-01-01

The Multi-Factor Interaction Model (MFIM) is used to evaluate the divot weight (foam weight ejected) from the launch external tanks. The multi-factor has sufficient degrees of freedom to evaluate a large number of factors that may contribute to the divot ejection. It also accommodates all interactions by its product form. Each factor has an exponent that satisfies only two points--the initial and final points. The exponent describes a monotonic path from the initial condition to the final. The exponent values are selected so that the described path makes sense in the absence of experimental data. In the present investigation, the data used was obtained by testing simulated specimens in launching conditions. Results show that the MFIM is an effective method of describing the divot weight ejected under the conditions investigated.

CFD simulations of transient load change on a high head Francis turbine

NASA Astrophysics Data System (ADS)

Jakobsen, Ken-Robert G.; Aasved Holst, Martin

2017-01-01

Motivated by the importance of better understanding the structural integrity of high-head hydraulic turbines operating at intermittent conditions, complete 360º steady-state and transient simulations of a Francis turbine are presented in this paper. The main target of the work has been to investigate different numerical approaches such as mesh deformation for different operating conditions. Steady-state simulations were performed at the best efficiency point (BEP) and used as initial conditions for the transient simulations considering load rejection from BEP to part load (BEP2PL) and during load acceptance from BEP to high load (BEP2HL). Simulation results were compared with experimental data available for the Francis-99 project where close agreement was found for the mesh independent solution. The transient load analyses showed general trends in accordance with the measurement reports, especially for the pressure in vaneless space that is of high importance regarding RSI effects. Some deviations were identified for the net head at load rejection for which further investigations will be conducted. All CFD simulations were performed at model scale with ANSYS CFX v. 17 at either 96 or 120 cores (2.60 GHz). The immersed boundary technique was tested during the initial stages of the project, but had to be abandoned due to severe memory requirements. Pressure amplitudes and other instantaneous results were not considered.

Development of the Orion Crew-Service Module Umbilical Retention and Release Mechanism

NASA Technical Reports Server (NTRS)

Delap, Damon C.; Glidden, Joel Micah; Lamoreaux, Christopher

2013-01-01

The Orion CSM umbilical retention and release mechanism supports and protects all of the cross-module commodities between the spacecrafts crew and service modules. These commodities include explosive transfer lines, wiring for power and data, and flexible hoses for ground purge and life support systems. The mechanism employs a single separation interface which is retained with pyrotechnically actuated separation bolts and supports roughly two dozen electrical and fluid connectors. When module separation is commanded, either for nominal on-orbit CONOPS or in the event of an abort, the mechanism must release the separation interface and sever all commodity connections within milliseconds of command receipt. There are a number of unique and novel aspects of the design solution developed by the Orion mechanisms team. The design is highly modular and can easily be adapted to other vehiclesmodules and alternate commodity sets. It will be flight tested during Orions Exploration Flight Test 1 (EFT-1) in 2014, and the Orion team anticipates reuse of the design for all future missions. The design packages fluid, electrical, and ordnance disconnects in a single separation interface. It supports abort separations even in cases where aerodynamic loading prevents the deployment of the umbilical arm. Unlike the Apollo CSM umbilical which was a destructive separation device, the Orion design is resettable and flight units can be tested for separation performance prior to flight.Initial development testing of the mechanisms separation interface resulted in binding failures due to connector misalignments. The separation interface was redesigned with a robust linear guide system, and the connector separation and boom deployment were separated into two discretely sequenced events. These changes addressed the root cause of the binding failure by providing better control of connector alignment. The new design was tuned and validated analytically via Monte Carlo simulation. The analytical validation was followed by a repeat of the initial test suite plus test cases at thermal extremes and test cases with imposed mechanical failures demonstrating fault tolerance. The mechanism was then exposed to the qualification vibration environment. Finally, separation testing was performed at full speed with live ordnance.All tests of the redesigned mechanism resulted in successful separation of the umbilical interface with adequate force margins and timing. The test data showed good agreement with the predictions of the Monte Carlo simulation. The simulation proved invaluable due to the number of variables affecting the separation and the uncertainty associated with each. The simulation allowed for rapid assessment of numerous trades and contingency scenarios, and can be easily reconfigured for varying commodity sets and connector layouts.

Initial stages of cavitation damage and erosion on copper and brass tested in a rotating disk device

NASA Technical Reports Server (NTRS)

Rao, P. V.; Rao, B. C. S.; Rao, N. S. L.

1982-01-01

In view of the differences in flow and experimental conditions, there has been a continuing debate as to whether or not the ultrasonic method of producing cavitation damage is similar to the damage occurring in cavitating flow systems, namely, venturi and rotating disk devices. In this paper, the progress of cavitation damage during incubation periods on polycrystalline copper and brass tested in a rotating disk device is presented. The results indicate several similarities and differences in the damage mechanism encountered in a rotating disk device (which simulates field rotary devices) and a magnetostriction apparatus. The macroscopic erosion appears similar to that in the vibratory device except for nonuniform erosion and apparent plastic flow during the initial damage phase.

Equipment. [for testing human space perception

NASA Technical Reports Server (NTRS)

1974-01-01

A discussion is presented on the problems encountered in designing and constructing a simulator to determine human vestibular response to a range of linear accelerations from 0 to 0.3 g's. Starting with a set of initial performance specifications, the designers combined an array of commercially available components into a system which, altough requiring further refinement before completion, shows considerable promise of fulfilling the initial requirements. The resulting system consists of a wheeled vehicle driven by a cable and drum arrangement, powered by a hydraulic-electric servo-valve. Technical design considerations are presented along with a discussion of the trade-offs between various component options. A description of the system characteristics as well as an analysis of preliminary test results and recommendations for future system improvements are included.

Potential indirect effects of aerosol on tropical cyclone development

NASA Astrophysics Data System (ADS)

Krall, Geoffrey

Observational and model evidence suggest that a 2008 Western Pacific typhoon (NURI) came into contact with and ingested elevated concentrations of aerosol as it neared the Chinese coast. This study uses a regional model with two-moment bin emulating microphysics to simulate the typhoon as it enters the field of elevated aerosol concentration. A continental field of cloud condensation nuclei (CCN) was prescribed based on satellite and global aerosol model output, then increased for further sensitivity tests. The typhoon was simulated for 96 hours beginning 17 August 2008, the final 60 of which were under varying CCN concentrations as it neared the Philippines and coastal China. The model was initialized with both global reanalysis model data and irregularly spaced dropsonde data from a 2008 observational campaign using an objective analysis routine. At 36 hours, the internal nudging of the model was switched off and allowed to evolve on its own. As the typhoon entered the field of elevated CCN in the sensitivity tests, the presence of additional CCN resulted in a significant perturbation of windspeed, convective fluxes, and hydrometeor species behavior. Initially ingested in the outer rainbands of the storm, the additional CCN resulted in an initial damping and subsequent invigoration of convection. The increase in convective fluxes strongly lag-correlates with increased amounts of supercooled liquid water within the storm domain. As the convection intensified in the outer rainbands the storm drifted over the developing cold-pools, affecting the inflow of air into the convective towers of the typhoon. Changes in the timing and amount of rain produced in each simulation resulted in differing cold-pool strengths and size. The presence of additional CCN increased resulted in an amplification of convection within the storm, except for the extremely high CCN concentration simulation, which showed a damped convection due to the advection of pristine ice away from the storm. This study examines the physical mechanisms that could potentially alter a tropical cyclone (TC) in intensity and dynamics upon ingesting elevated levels of CCN.

Generating Inviscid and Viscous Fluid Flow Simulations over a Surface Using a Quasi-simultaneous Technique

NASA Technical Reports Server (NTRS)

Sturdza, Peter (Inventor); Martins-Rivas, Herve (Inventor); Suzuki, Yoshifumi (Inventor)

2014-01-01

A fluid-flow simulation over a computer-generated surface is generated using a quasi-simultaneous technique. The simulation includes a fluid-flow mesh of inviscid and boundary-layer fluid cells. An initial fluid property for an inviscid fluid cell is determined using an inviscid fluid simulation that does not simulate fluid viscous effects. An initial boundary-layer fluid property a boundary-layer fluid cell is determined using the initial fluid property and a viscous fluid simulation that simulates fluid viscous effects. An updated boundary-layer fluid property is determined for the boundary-layer fluid cell using the initial fluid property, initial boundary-layer fluid property, and an interaction law. The interaction law approximates the inviscid fluid simulation using a matrix of aerodynamic influence coefficients computed using a two-dimensional surface panel technique and a fluid-property vector. An updated fluid property is determined for the inviscid fluid cell using the updated boundary-layer fluid property.

A new and inexpensive non-bit-for-bit solution reproducibility test based on time step convergence (TSC1.0)

NASA Astrophysics Data System (ADS)

Wan, Hui; Zhang, Kai; Rasch, Philip J.; Singh, Balwinder; Chen, Xingyuan; Edwards, Jim

2017-02-01

A test procedure is proposed for identifying numerically significant solution changes in evolution equations used in atmospheric models. The test issues a fail signal when any code modifications or computing environment changes lead to solution differences that exceed the known time step sensitivity of the reference model. Initial evidence is provided using the Community Atmosphere Model (CAM) version 5.3 that the proposed procedure can be used to distinguish rounding-level solution changes from impacts of compiler optimization or parameter perturbation, which are known to cause substantial differences in the simulated climate. The test is not exhaustive since it does not detect issues associated with diagnostic calculations that do not feedback to the model state variables. Nevertheless, it provides a practical and objective way to assess the significance of solution changes. The short simulation length implies low computational cost. The independence between ensemble members allows for parallel execution of all simulations, thus facilitating fast turnaround. The new method is simple to implement since it does not require any code modifications. We expect that the same methodology can be used for any geophysical model to which the concept of time step convergence is applicable.

Reactivity Initiated Accident Simulation to Inform Transient Testing of Candidate Advanced Cladding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, Nicholas R; Wysocki, Aaron J; Terrani, Kurt A

2016-01-01

Abstract. Advanced cladding materials with potentially enhanced accident tolerance will yield different light water reactor performance and safety characteristics than the present zirconium-based cladding alloys. These differences are due to different cladding material properties and responses to the transient, and to some extent, reactor physics, thermal, and hydraulic characteristics. Some of the differences in reactors physics characteristics will be driven by the fundamental properties (e.g., absorption in iron for an iron-based cladding) and others will be driven by design modifications necessitated by the candidate cladding materials (e.g., a larger fuel pellet to compensate for parasitic absorption). Potential changes in thermalmore » hydraulic limits after transition from the current zirconium-based cladding to the advanced materials will also affect the transient response of the integral fuel. This paper leverages three-dimensional reactor core simulation capabilities to inform on appropriate experimental test conditions for candidate advanced cladding materials in a control rod ejection event. These test conditions are using three-dimensional nodal kinetics simulations of a reactivity initiated accident (RIA) in a representative state-of-the-art pressurized water reactor with both nuclear-grade iron-chromium-aluminum (FeCrAl) and silicon carbide based (SiC-SiC) cladding materials. The effort yields boundary conditions for experimental mechanical tests, specifically peak cladding strain during the power pulse following the rod ejection. The impact of candidate cladding materials on the reactor kinetics behavior of RIA progression versus reference zirconium cladding is predominantly due to differences in: (1) fuel mass/volume/specific power density, (2) spectral effects due to parasitic neutron absorption, (3) control rod worth due to hardened (or softened) spectrum, and (4) initial conditions due to power peaking and neutron transport cross sections in the equilibrium cycle cores due to hardened (or softened) spectrum. This study shows minimal impact of SiC-based cladding configurations on the transient response versus reference zirconium-based cladding. However, the FeCrAl cladding response indicates similar energy deposition, but with significantly shorter pulses of higher magnitude. Therefore the FeCrAl-based cases have a more rapid fuel thermal expansion rate and the resultant pellet-cladding interaction occurs more rapidly.« less

Fatigue limits of monolithic Y-TZP three-unit-fixed dental prostheses: effect of grinding at the gingival zone of the connector

PubMed Central

Amaral, Marina; Rocha, Regina FV; Melo, Renata Marques; Pereira, Gabriel KR; Zhang, Yu; Valandro, Luiz Felipe; Bottino, Marco Antonio

2017-01-01

Objectives To determine the fatigue limits of three-unit monolithic zirconia FDPs before and after grinding of the gingival areas of connectors with diamond burs. Material and Methods FDPs were milled from pre-sintered blocks of zirconia simulating the absence of the first mandibular molar. Half of the specimens were subjected to grinding, simulating clinical adjustment, and all of them were subjected to glazing procedure. Additional specimens were manufactured for roughness analysis. FDPs were adhesively cemented onto glass-fiber reinforced epoxy resin abutments. Fatigue limits and standard deviations were obtained using a staircase fatigue method (n = 20, 100,000 loading cycles/5 Hz). The initial test load was 70% of the mean load-to-fracture (n = 3) and load increments were 5% of the initial test load for both the control and ground specimens. Data were compared by Student’s T-test (α ≤ 0.05). Results Both the control and ground groups exhibited similar values of load-to-fracture and fatigue limits. Neither the surface treatments nor ageing affected the surface roughness of the specimens. Conclusions The damage induced by grinding with fine-grit diamond bur in the gingival area of the connectors did not decrease the fatigue limit of the three-unit monolithic zirconia FDP. PMID:28494273

On the relevance of modeling viscoelastic bending behavior in finite element forming simulation of continuously fiber reinforced thermoplastics

NASA Astrophysics Data System (ADS)

Dörr, Dominik; Schirmaier, Fabian J.; Henning, Frank; Kärger, Luise

2017-10-01

Finite Element (FE) forming simulation offers the possibility of a detailed analysis of the deformation behavior of multilayered thermoplastic blanks during forming, considering material behavior and process conditions. Rate-dependent bending behavior is a material characteristic, which is so far not considered in FE forming simulation of pre-impregnated, continuously fiber reinforced polymers (CFRPs). Therefore, an approach for modeling viscoelastic bending behavior in FE composite forming simulation is presented in this work. The presented approach accounts for the distinct rate-dependent bending behavior of e.g. thermoplastic CFRPs at process conditions. The approach is based on a Voigt-Kelvin (VK) and a generalized Maxwell (GM) approach, implemented within a FE forming simulation framework implemented in several user-subroutines of the commercially available FE solver Abaqus. The VK, GM, as well as purely elastic bending modeling approaches are parameterized according to dynamic bending characterization results for a PA6-CF UD-tape. It is found that only the GM approach is capable to represent the bending deformation characteristic for all of the considered bending deformation rates. The parameterized bending modeling approaches are applied to a hemisphere test and to a generic geometry. A comparison of the forming simulation results of the generic geometry to experimental tests show a good agreement between simulation and experiments. Furthermore, the simulation results reveal that especially a correct modeling of the initial bending stiffness is relevant for the prediction of wrinkling behavior, as a similar onset of wrinkles is observed for the GM, the VK and an elastic approach, fitted to the stiffness observed in the dynamic rheometer test for low curvatures. Hence, characterization and modeling of rate-dependent bending behavior is crucial for FE forming simulation of thermoplastic CFRPs.

From Modeling of Plasticity in Single-Crystal Superalloys to High-Resolution X-rays Three-Crystal Diffractometer Peaks Simulation

NASA Astrophysics Data System (ADS)

Jacques, Alain

2016-12-01

The dislocation-based modeling of the high-temperature creep of two-phased single-crystal superalloys requires input data beyond strain vs time curves. This may be obtained by use of in situ experiments combining high-temperature creep tests with high-resolution synchrotron three-crystal diffractometry. Such tests give access to changes in phase volume fractions and to the average components of the stress tensor in each phase as well as the plastic strain of each phase. Further progress may be obtained by a new method making intensive use of the Fast Fourier Transform, and first modeling the behavior of a representative volume of material (stress fields, plastic strain, dislocation densities…), then simulating directly the corresponding diffraction peaks, taking into account the displacement field within the material, chemical variations, and beam coherence. Initial tests indicate that the simulated peak shapes are close to the experimental ones and are quite sensitive to the details of the microstructure and to dislocation densities at interfaces and within the soft γ phase.

Modeling and analysis of pinhole occulter experiment: Initial study phase

NASA Technical Reports Server (NTRS)

Vandervoort, R. J.

1985-01-01

The feasibility of using a generic simulation, TREETOPS, to simulate the Pinhole/Occulter Facility (P/OF) to be tested on the space shuttle was demonstrated. The baseline control system was used to determine the pointing performance of the P/OF. The task included modeling the structure as a three body problem (shuttle-instrument pointing system- P/OP) including the flexibility of the 32 meter P/OF boom. Modeling of sensors, actuators, and control algorithms was also required. Detailed mathematical models for the structure, sensors, and actuators are presented, as well as the control algorithm and corresponding design procedure. Closed loop performance using this controller and computer listings for the simulator are also given.

Improved initial guess with semi-subpixel level accuracy in digital image correlation by feature-based method

NASA Astrophysics Data System (ADS)

Zhang, Yunlu; Yan, Lei; Liou, Frank

2018-05-01

The quality initial guess of deformation parameters in digital image correlation (DIC) has a serious impact on convergence, robustness, and efficiency of the following subpixel level searching stage. In this work, an improved feature-based initial guess (FB-IG) scheme is presented to provide initial guess for points of interest (POIs) inside a large region. Oriented FAST and Rotated BRIEF (ORB) features are semi-uniformly extracted from the region of interest (ROI) and matched to provide initial deformation information. False matched pairs are eliminated by the novel feature guided Gaussian mixture model (FG-GMM) point set registration algorithm, and nonuniform deformation parameters of the versatile reproducing kernel Hilbert space (RKHS) function are calculated simultaneously. Validations on simulated images and real-world mini tensile test verify that this scheme can robustly and accurately compute initial guesses with semi-subpixel level accuracy in cases with small or large translation, deformation, or rotation.

An Enriched Shell Finite Element for Progressive Damage Simulation in Composite Laminates

NASA Technical Reports Server (NTRS)

McElroy, Mark W.

2016-01-01

A formulation is presented for an enriched shell nite element capable of progressive damage simulation in composite laminates. The element uses a discrete adaptive splitting approach for damage representation that allows for a straightforward model creation procedure based on an initially low delity mesh. The enriched element is veri ed for Mode I, Mode II, and mixed Mode I/II delamination simulation using numerical benchmark data. Experimental validation is performed using test data from a delamination-migration experiment. Good correlation was found between the enriched shell element model results and the numerical and experimental data sets. The work presented in this paper is meant to serve as a rst milestone in the enriched element's development with an ultimate goal of simulating three-dimensional progressive damage processes in multidirectional laminates.

Modelling and validation land-atmospheric heat fluxes by using classical surface parameters over the Tibetan Plateau

NASA Astrophysics Data System (ADS)

Ma, W.; Ma, Y.; Hu, Z.; Zhong, L.

2017-12-01

In this study, a land-atmosphere model was initialized by ingesting AMSR-E products, and the results were compared with the default model configuration and with in situ long-term CAMP/Tibet observations. Firstly our field observation sites will be introduced based on ITPCAS (Institute of Tibetan Plateau Research, Chinese Academy of Sciences). Then, a land-atmosphere model was initialized by ingesting AMSR-E products, and the results were compared with the default model configuration and with in situ long-term CAMP/Tibet observations. The differences between the AMSR-E initialized model runs with the default model configuration and in situ data showed an apparent inconsistency in the model-simulated land surface heat fluxes. The results showed that the soil moisture was sensitive to the specific model configuration. To evaluate and verify the model stability, a long-term modeling study with AMSR-E soil moisture data ingestion was performed. Based on test simulations, AMSR-E data were assimilated into an atmospheric model for July and August 2007. The results showed that the land surface fluxes agreed well with both the in situ data and the results of the default model configuration. Therefore, the simulation can be used to retrieve land surface heat fluxes from an atmospheric model over the Tibetan Plateau.

A Study of the Unstable Modes in High Mach Number Gaseous Jets and Shear Layers

NASA Astrophysics Data System (ADS)

Bassett, Gene Marcel

1993-01-01

Instabilities affecting the propagation of supersonic gaseous jets have been studied using high resolution computer simulations with the Piecewise-Parabolic-Method (PPM). These results are discussed in relation to jets from galactic nuclei. These studies involve a detailed treatment of a single section of a very long jet, approximating the dynamics by using periodic boundary conditions. Shear layer simulations have explored the effects of shear layers on the growth of nonlinear instabilities. Convergence of the numerical approximations has been tested by comparing jet simulations with different grid resolutions. The effects of initial conditions and geometry on the dominant disruptive instabilities have also been explored. Simulations of shear layers with a variety of thicknesses, Mach numbers and densities perturbed by incident sound waves imply that the time for the excited kink modes to grow large in amplitude and disrupt the shear layer is taug = (546 +/- 24) (M/4)^{1.7 } (Apert/0.02) ^{-0.4} delta/c, where M is the jet Mach number, delta is the half-width of the shear layer, and A_ {pert} is the perturbation amplitude. For simulations of periodic jets, the initial velocity perturbations set up zig-zag shock patterns inside the jet. In each case a single zig-zag shock pattern (an odd mode) or a double zig-zag shock pattern (an even mode) grows to dominate the flow. The dominant kink instability responsible for these shock patterns moves approximately at the linear resonance velocity, nu_ {mode} = cextnu_ {relative}/(cjet + c_ {ext}). For high resolution simulations (those with 150 or more computational zones across the jet width), the even mode dominates if the even penetration is higher in amplitude initially than the odd perturbation. For low resolution simulations, the odd mode dominates even for a stronger even mode perturbation. In high resolution simulations the jet boundary rolls up and large amounts of external gas are entrained into the jet. In low resolution simulations this entrainment process is impeded by numerical viscosity. The three-dimensional jet simulations behave similarly to two-dimensional jet runs with the same grid resolutions.

Ion Transport and Acceleration at Dipolarization Fronts: High-Resolution MHD/Test-Particle Simulations

NASA Astrophysics Data System (ADS)

Ukhorskiy, A. Y.; Sorathia, K.; Merkin, V. G.; Sitnov, M. I.; Mitchell, D. G.; Wiltberger, M. J.; Lyon, J.

2017-12-01

Much of plasma heating and transport from the magnetotail into the inner magnetosphere occurs in the form of mesoscale discrete injections associated with sharp dipolarizations of magnetic field (dipolarization fronts). In this study we investigate the mechanisms of ion acceleration at dipolarization fronts in a high-resolution global magnetospheric MHD model (LFM). We use large-scale three-dimensional test-particle simulations (CHIMP) to address the following science questions: 1) what are the characteristic scales of dipolarization regions that can stably trap ions? 2) what role does the trapping play in ion transport and acceleration? 3) how does it depend on particle energy and distance from Earth? 4) to what extent ion acceleration is adiabatic? High-resolution LFM was run using idealized solar wind conditions with fixed nominal values of density and velocity and a southward IMF component of -5 nT. To simulate ion interaction with dipolarization fronts, a large ensemble of test particles distributed in energy, pitch-angle, and gyrophase was initialized inside one of the LFM dipolarization channels in the magnetotail. Full Lorentz ion trajectories were then computed over the course of the front inward propagation from the distance of 17 to 6 Earth radii. A large fraction of ions with different initial energies stayed in phase with the front over the entire distance. The effect of magnetic trapping at different energies was elucidated with a correlation of the ion guiding center and the ExB drift velocities. The role of trapping in ion energization was quantified by comparing the partial pressure of ions that exhibit trapping to the pressure of all trapped ions.

Flow and fracture behavior of aluminum alloy 6082-T6 at different tensile strain rates and triaxialities

PubMed Central

Chen, Xuanzhen; Peng, Shan; Yao, Song; Chen, Chao; Xu, Ping

2017-01-01

This study aims to investigate the flow and fracture behavior of aluminum alloy 6082-T6 (AA6082-T6) at different strain rates and triaxialities. Two groups of Charpy impact tests were carried out to further investigate its dynamic impact fracture property. A series of tensile tests and numerical simulations based on finite element analysis (FEA) were performed. Experimental data on smooth specimens under various strain rates ranging from 0.0001~3400 s-1 shows that AA6082-T6 is rather insensitive to strain rates in general. However, clear rate sensitivity was observed in the range of 0.001~1 s-1 while such a characteristic is counteracted by the adiabatic heating of specimens under high strain rates. A Johnson-Cook constitutive model was proposed based on tensile tests at different strain rates. In this study, the average stress triaxiality and equivalent plastic strain at facture obtained from numerical simulations were used for the calibration of J-C fracture model. Both of the J-C constitutive model and fracture model were employed in numerical simulations and the results was compared with experimental results. The calibrated J-C fracture model exhibits higher accuracy than the J-C fracture model obtained by the common method in predicting the fracture behavior of AA6082-T6. Finally, the Scanning Electron Microscope (SEM) of fractured specimens with different initial stress triaxialities were analyzed. The magnified fractographs indicate that high initial stress triaxiality likely results in dimple fracture. PMID:28759617

Parametric Testing of Launch Vehicle FDDR Models

NASA Technical Reports Server (NTRS)

Schumann, Johann; Bajwa, Anupa; Berg, Peter; Thirumalainambi, Rajkumar

2011-01-01

For the safe operation of a complex system like a (manned) launch vehicle, real-time information about the state of the system and potential faults is extremely important. The on-board FDDR (Failure Detection, Diagnostics, and Response) system is a software system to detect and identify failures, provide real-time diagnostics, and to initiate fault recovery and mitigation. The ERIS (Evaluation of Rocket Integrated Subsystems) failure simulation is a unified Matlab/Simulink model of the Ares I Launch Vehicle with modular, hierarchical subsystems and components. With this model, the nominal flight performance characteristics can be studied. Additionally, failures can be injected to see their effects on vehicle state and on vehicle behavior. A comprehensive test and analysis of such a complicated model is virtually impossible. In this paper, we will describe, how parametric testing (PT) can be used to support testing and analysis of the ERIS failure simulation. PT uses a combination of Monte Carlo techniques with n-factor combinatorial exploration to generate a small, yet comprehensive set of parameters for the test runs. For the analysis of the high-dimensional simulation data, we are using multivariate clustering to automatically find structure in this high-dimensional data space. Our tools can generate detailed HTML reports that facilitate the analysis.

CF6 Jet Engine Performance Improvement Program: High Pressure Turbine Aerodynamic Performance Improvement

NASA Technical Reports Server (NTRS)

Fasching, W. A.

1980-01-01

The improved single shank high pressure turbine design was evaluated in component tests consisting of performance, heat transfer and mechanical tests, and in core engine tests. The instrumented core engine test verified the thermal, mechanical, and aeromechanical characteristics of the improved turbine design. An endurance test subjected the improved single shank turbine to 1000 simulated flight cycles, the equivalent of approximately 3000 hours of typical airline service. Initial back-to-back engine tests demonstrated an improvement in cruise sfc of 1.3% and a reduction in exhaust gas temperature of 10 C. An additional improvement of 0.3% in cruise sfc and 6 C in EGT is projected for long service engines.

Super NiCd Open-Circuit Storage and Low Earth Orbit (LEO) Life Test Evaluation

NASA Technical Reports Server (NTRS)

Baer, Jean Marie; Hwang, Warren C.; Ang, Valerie J.; Hayden, Jeff; Rao, Gopalakrishna; Day, John H. (Technical Monitor)

2002-01-01

This presentation discusses Air Force tests performed on super NiCd cells to measure their performance under conditions simulating Low Earth Orbit (LEO) conditions. Super NiCd cells offer potential advantages over existing NiCd cell designs including advanced cell design with improved separator material and electrode making processes, but handling and storage requires active charging. These tests conclude that the super NiCd cells support generic Air Force qualifications for conventional LEO missions (up to five years duration) and that handling and storage may not actually require active charging as previously assumed. Topics covered include: Test Plan, Initial Characterization Tests, Open-Circuit Storage Tests, and post storage capacities.

Nickel hydrogen low Earth orbit life testing

NASA Technical Reports Server (NTRS)

Badcock, C. C.; Haag, R. L.

1986-01-01

A program to demonstrate the long term reliability of NiH2 cells in low Earth orbits (LEO) and support use in mid-altitude orbits (MAO) was initiated. Both 3.5 and 4.5 inch diameter nickel hydrogen cells are included in the test plan. Cells from all U.S. vendors are to be tested. The tests will be performed at -5 and 10 C at 40 and 60% DOD for LEO orbit and 10 C and 80% DOD for MAO orbit simulations. The goals of the testing are 20,000 cycles at 60% DOD and 30,000 cycles at 40% DOD. Cells are presently undergoing acceptance and characterization testing at Naval Weapons Systems Center, Crane.

Arcing in Leo and Geo Simulated Environments: Comparative Analysis

NASA Technical Reports Server (NTRS)

Vayner, Boris V.; Ferguson, Dale C.; Galofaro, Joel TY.

2006-01-01

Comprehensive tests of two solar array samples in simulated Low Earth Orbit (LEO) and Geosynchronous Orbit (GEO) environments have demonstrated that the arc inception voltage was 2-3 times lower in the LEO plasma than in the GEO vacuum. Arc current pulse wave forms are also essentially different in these environments. Moreover, the wide variations of pulse forms do not allow introducing the definition of a "standard arc wave form" even in GEO conditions. Visual inspection of the samples after testing in a GEO environment revealed considerable damage on coverglass surfaces and interconnects. These harmful consequences can be explained by the discharge energy being one order of magnitude higher in vacuum than in background plasma. The tests also revealed a potential danger of powerful electrostatic discharges that could be initiated on the solar array surface of a satellite in GEO during the ignition of an arcjet thruster.

Development of a virtual lab for practical eLearning in eHealth.

PubMed

Herzog, Juliane; Forjan, Mathias; Sauermann, Stefan; Mense, Alexander; Urbauer, Philipp

2015-01-01

In recent years an ongoing development in educational offers for professionals working in the field of eHealth has been observed. This education is increasingly offered in the form of eLearning courses. Furthermore, it can be seen that simulations are a valuable part to support the knowledge transfer. Based on the knowledge profiles defined for eHealth courses a virtual lab should be developed. For this purpose, a subset of skills and a use case is determined. After searching and evaluating appropriate simulating and testing tools six tools were chosen to implement the use case practically. Within an UML use case diagram the interaction between the tools and the user is represented. Initially tests have shown good results of the tools' feasibility. After an extensive testing phase the tools should be integrated in the eHealth eLearning courses.

The influence of autocorrelation in signature extraction: An example from a geobotanical investigation of Cotter Basin, Montana

NASA Technical Reports Server (NTRS)

Labovitz, M. L.; Masuoka, E. J. (Principal Investigator)

1981-01-01

The presence of positive serial correlation (autocorrelation) in remotely sensed data results in an underestimate of the variance-covariance matrix when calculated using contiguous pixels. This underestimate produces an inflation in F statistics. For a set of Thematic Mapper Simulator data (TMS), used to test the ability to discriminate a known geobotanical anomaly from its background, the inflation in F statistics related to serial correlation is between 7 and 70 times. This means that significance tests of means of the spectral bands initially appear to suggest that the anomalous site is very different in spectral reflectance and emittance from its background sites. However, this difference often disappears and is always dramatically reduced when compared to frequency distributions of test statistics produced by the comparison of simulated training sets possessing equal means, but which are composed of autocorrelated observations.

Effect of Surface Impulsive Thermal Loads on Fatigue Behavior of Constant Volume Propulsion Engine Combustor Materials

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Fox, Dennis S.; Miller, Robert A.; Ghosn, Louis J.; Kalluri, Sreeramesh

2004-01-01

The development of advanced high performance constant-volume-combustion-cycle engines (CVCCE) requires robust design of the engine components that are capable of enduring harsh combustion environments under high frequency thermal and mechanical fatigue conditions. In this study, a simulated engine test rig has been established to evaluate thermal fatigue behavior of a candidate engine combustor material, Haynes 188, under superimposed CO2 laser surface impulsive thermal loads (30 to 100 Hz) in conjunction with the mechanical fatigue loads (10 Hz). The mechanical high cycle fatigue (HCF) testing of some laser pre-exposed specimens has also been conducted under a frequency of 100 Hz to determine the laser surface damage effect. The test results have indicated that material surface oxidation and creep-enhanced fatigue is an important mechanism for the surface crack initiation and propagation under the simulated CVCCE engine conditions.

Predicting Operator Execution Times Using CogTool

NASA Technical Reports Server (NTRS)

Santiago-Espada, Yamira; Latorella, Kara A.

2013-01-01

Researchers and developers of NextGen systems can use predictive human performance modeling tools as an initial approach to obtain skilled user performance times analytically, before system testing with users. This paper describes the CogTool models for a two pilot crew executing two different types of a datalink clearance acceptance tasks, and on two different simulation platforms. The CogTool time estimates for accepting and executing Required Time of Arrival and Interval Management clearances were compared to empirical data observed in video tapes and registered in simulation files. Results indicate no statistically significant difference between empirical data and the CogTool predictions. A population comparison test found no significant differences between the CogTool estimates and the empirical execution times for any of the four test conditions. We discuss modeling caveats and considerations for applying CogTool to crew performance modeling in advanced cockpit environments.

Electron emission from condensed phase material induced by fast protons.

PubMed

Shinpaugh, J L; McLawhorn, R A; McLawhorn, S L; Carnes, K D; Dingfelder, M; Travia, A; Toburen, L H

2011-02-01

Monte Carlo track simulation has become an important tool in radiobiology. Monte Carlo transport codes commonly rely on elastic and inelastic electron scattering cross sections determined using theoretical methods supplemented with gas-phase data; experimental condensed phase data are often unavailable or infeasible. The largest uncertainties in the theoretical methods exist for low-energy electrons, which are important for simulating electron track ends. To test the reliability of these codes to deal with low-energy electron transport, yields of low-energy secondary electrons ejected from thin foils have been measured following passage of fast protons. Fast ions, where interaction cross sections are well known, provide the initial spectrum of low-energy electrons that subsequently undergo elastic and inelastic scattering in the material before exiting the foil surface and being detected. These data, measured as a function of the energy and angle of the emerging electrons, can provide tests of the physics of electron transport. Initial measurements from amorphous solid water frozen to a copper substrate indicated substantial disagreement with MC simulation, although questions remained because of target charging. More recent studies, using different freezing techniques, do not exhibit charging, but confirm the disagreement seen earlier between theory and experiment. One now has additional data on the absolute differential electron yields from copper, aluminum and gold, as well as for thin films of frozen hydrocarbons. Representative data are presented.

Electron emission from condensed phase material induced by fast protons†

PubMed Central

Shinpaugh, J. L.; McLawhorn, R. A.; McLawhorn, S. L.; Carnes, K. D.; Dingfelder, M.; Travia, A.; Toburen, L. H.

2011-01-01

Monte Carlo track simulation has become an important tool in radiobiology. Monte Carlo transport codes commonly rely on elastic and inelastic electron scattering cross sections determined using theoretical methods supplemented with gas-phase data; experimental condensed phase data are often unavailable or infeasible. The largest uncertainties in the theoretical methods exist for low-energy electrons, which are important for simulating electron track ends. To test the reliability of these codes to deal with low-energy electron transport, yields of low-energy secondary electrons ejected from thin foils have been measured following passage of fast protons. Fast ions, where interaction cross sections are well known, provide the initial spectrum of low-energy electrons that subsequently undergo elastic and inelastic scattering in the material before exiting the foil surface and being detected. These data, measured as a function of the energy and angle of the emerging electrons, can provide tests of the physics of electron transport. Initial measurements from amorphous solid water frozen to a copper substrate indicated substantial disagreement with MC simulation, although questions remained because of target charging. More recent studies, using different freezing techniques, do not exhibit charging, but confirm the disagreement seen earlier between theory and experiment. One now has additional data on the absolute differential electron yields from copper, aluminum and gold, as well as for thin films of frozen hydrocarbons. Representative data are presented. PMID:21183539

Orbiter/payload contamination control assessment support

NASA Technical Reports Server (NTRS)

Rantanen, R. O.; Strange, D. A.; Hetrick, M. A.

1978-01-01

The development and integration of 16 payload bay liner filters into the existing shuttle/payload contamination evaluation (SPACE) computer program is discussed as well as an initial mission profile model. As part of the mission profile model, a thermal conversion program, a temperature cycling routine, a flexible plot routine and a mission simulation of orbital flight test 3 are presented.

Analysis of formation pressure test results in the Mount Elbert methane hydrate reservoir through numerical simulation

USGS Publications Warehouse

Kurihara, M.; Sato, A.; Funatsu, K.; Ouchi, H.; Masuda, Y.; Narita, H.; Collett, T.S.

2011-01-01

Targeting the methane hydrate (MH) bearing units C and D at the Mount Elbert prospect on the Alaska North Slope, four MDT (Modular Dynamic Formation Tester) tests were conducted in February 2007. The C2 MDT test was selected for history matching simulation in the MH Simulator Code Comparison Study. Through history matching simulation, the physical and chemical properties of the unit C were adjusted, which suggested the most likely reservoir properties of this unit. Based on these properties thus tuned, the numerical models replicating "Mount Elbert C2 zone like reservoir" "PBU L-Pad like reservoir" and "PBU L-Pad down dip like reservoir" were constructed. The long term production performances of wells in these reservoirs were then forecasted assuming the MH dissociation and production by the methods of depressurization, combination of depressurization and wellbore heating, and hot water huff and puff. The predicted cumulative gas production ranges from 2.16??106m3/well to 8.22??108m3/well depending mainly on the initial temperature of the reservoir and on the production method.This paper describes the details of modeling and history matching simulation. This paper also presents the results of the examinations on the effects of reservoir properties on MH dissociation and production performances under the application of the depressurization and thermal methods. ?? 2010 Elsevier Ltd.

The LISA benchtop simulator at the University of Florida

NASA Astrophysics Data System (ADS)

Thorpe, James; Cruz, Rachel; Guntaka, Sridhar; Mueller, Guido

2006-11-01

The Laser Interferometer Space Antenna (LISA) is a joint NASA-ESA mission to detect gravitational radiation in space. The detector is designed to see gravitational waves from various exciting sources in the frequency range of 3x10-5 to 1 Hz. LISA consists of three spacecraft forming a triangle with 5x10^9 m long arms. The spacecraft house proof masses and act to shield the proof masses from external forces so that they act as freely-falling test particles of the gravitational radiation. Laser interferometry is used to monitor the distance between proof masses on different spacecraft and will be designed to see variations on the order of 10 pm. Pre-stabilization, arm-locking, and time delay interferometry (TDI) will be employed to meet this sensitivity. At the University of Florida, we are developing an experimental LISA simulator to test aspects of LISA interferometry. The foundation of the simulator is a pair of cavity-stabilized lasers that provide realistic, LISA-like phase noise for our measurements. The light travel time between spacecraft is recreated in the lab by use of an electronic phase delay technique. Initial tests of the simulator have focused on phasemeter implementation, first-generation TDI, and arm-locking. We will present results from these experiments as well as discuss current and future upgrades in the effort to make the LISA simulator as realistic as possible.

Wind-tunnel development of an SR-71 aerospike rocket flight test configuration

NASA Technical Reports Server (NTRS)

Smith, Stephen C.; Shirakata, Norm; Moes, Timothy R.; Cobleigh, Brent R.; Conners, Timothy H.

1996-01-01

A flight experiment has been proposed to investigate the performance of an aerospike rocket motor installed in a lifting body configuration. An SR-71 airplane would be used to carry the aerospike configuration to the desired flight test conditions. Wind-tunnel tests were completed on a 4-percent scale SR-71 airplane with the aerospike pod mounted in various locations on the upper fuselage. Testing was accomplished using sting and blade mounts from Mach 0.6 to Mach 3.2. Initial test objectives included assessing transonic drag and supersonic lateral-directional stability and control. During these tests, flight simulations were run with wind-tunnel data to assess the acceptability of the configurations. Early testing demonstrated that the initial configuration with the aerospike pod near the SR-71 center of gravity was unsuitable because of large nosedown pitching moments at transonic speeds. The excessive trim drag resulting from accommodating this pitching moment far exceeded the excess thrust capability of the airplane. Wind-tunnel testing continued in an attempt to find a configuration suitable for flight test. Multiple configurations were tested. Results indicate that an aft-mounted model configuration possessed acceptable performance, stability, and control characteristics.

Pitting Behavior of L415 Pipeline Steel in Simulated Leaching Liquid Environment

NASA Astrophysics Data System (ADS)

Wan, H. X.; Yang, X. J.; Liu, Z. Y.; Song, D. D.; Du, C. W.; Li, X. G.

2017-02-01

The corrosion behavior and laws of the west-east gas pressure pipeline of L415 steel were studied in simulated leaching liquid. The failure of the L415 steel during the pressure testing process was investigated using electrochemical polarization, electrochemical impedance spectroscopy, and immersion test. The corrosion rate of the L415 steel increased with ion concentration in the leaching liquid. This rate reached about 0.8 mm a-1 and belonged to the severe corrosion grade. Pitting corrosion was observed in various simulated solutions with different aggressive species concentrations. The original ion concentration in the leaching liquid (1×) is the key factor influencing pitting initiation and development. Pitting showed easy nucleation, and its growth rate was relatively slow, in the basic simulating solution of the leach liquid (i.e., the ion content is compactable to the real condition in the rust on the inner steel pipe surface). Pitting was also highly sensitive and easily grew in the solution with doubled ion concentration in the basic simulating solution (2×). A uniform corrosion, instead of pitting, mainly occurred when the ion concentration was up to 10× of the basic solution.

Creep Strain and Strain Rate Response of 2219 Al Alloy at High Stress Levels

NASA Technical Reports Server (NTRS)

Taminger, Karen M. B.; Wagner, John A.; Lisagor, W. Barry

1998-01-01

As a result of high localized plastic deformation experienced during proof testing in an International Space Station connecting module, a study was undertaken to determine the deformation response of a 2219-T851 roll forging. After prestraining 2219-T851 Al specimens to simulate strains observed during the proof testing, creep tests were conducted in the temperature range from ambient temperature to 107 C (225 F) at stress levels approaching the ultimate tensile strength of 2219-T851 Al. Strain-time histories and strain rate responses were examined. The strain rate response was extremely high initially, but decayed rapidly, spanning as much as five orders of magnitude during primary creep. Select specimens were subjected to incremental step loading and exhibited initial creep rates of similar magnitude for each load step. Although the creep rates decreased quickly at all loads, the creep rates dropped faster and reached lower strain rate levels for lower applied loads. The initial creep rate and creep rate decay associated with primary creep were similar for specimens with and without prestrain; however, prestraining (strain hardening) the specimens, as in the aforementioned proof test, resulted in significantly longer creep life.

Subject specific finite element modeling of periprosthetic femoral fracture using element deactivation to simulate bone failure.

PubMed

Miles, Brad; Kolos, Elizabeth; Walter, William L; Appleyard, Richard; Shi, Angela; Li, Qing; Ruys, Andrew J

2015-06-01

Subject-specific finite element (FE) modeling methodology could predict peri-prosthetic femoral fracture (PFF) for cementless hip arthoplasty in the early postoperative period. This study develops methodology for subject-specific finite element modeling by using the element deactivation technique to simulate bone failure and validate with experimental testing, thereby predicting peri-prosthetic femoral fracture in the early postoperative period. Material assignments for biphasic and triphasic models were undertaken. Failure modeling with the element deactivation feature available in ABAQUS 6.9 was used to simulate a crack initiation and propagation in the bony tissue based upon a threshold of fracture strain. The crack mode for the biphasic models was very similar to the experimental testing crack mode, with a similar shape and path of the crack. The fracture load is sensitive to the friction coefficient at the implant-bony interface. The development of a novel technique to simulate bone failure by element deactivation of subject-specific finite element models could aid prediction of fracture load in addition to fracture risk characterization for PFF. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

Assessment of simulated high-dose partial-body irradiation by PCC-R assay.

PubMed

Romero, Ivonne; García, Omar; Lamadrid, Ana I; Gregoire, Eric; González, Jorge E; Morales, Wilfredo; Martin, Cécile; Barquinero, Joan-Francesc; Voisin, Philippe

2013-09-01

The estimation of the dose and the irradiated fraction of the body is important information in the primary medical response in case of a radiological accident. The PCC-R assay has been developed for high-dose estimations, but little attention has been given to its applicability for partial-body irradiations. In the present work we estimated the doses and the percentage of the irradiated fraction in simulated partial-body radiation exposures at high doses using the PCC-R assay. Peripheral whole blood of three healthy donors was exposed to doses from 0-20 Gy, with ⁶⁰Co gamma radiation. To simulate partial body irradiations, irradiated and non-irradiated blood was mixed to obtain proportions of irradiated blood from 10-90%. Lymphocyte cultures were treated with Colcemid and Calyculin-A before harvest. Conventional and triage scores were performed for each dose, proportion of irradiated blood and donor. The Papworth's u test was used to evaluate the PCC-R distribution per cell. A dose-response relationship was fitted according to the maximum likelihood method using the frequencies of PCC-R obtained from 100% irradiated blood. The dose to the partially irradiated blood was estimated using the Contaminated Poisson method. A new D₀ value of 10.9 Gy was calculated and used to estimate the initial fraction of irradiated cells. The results presented here indicate that by PCC-R it is possible to distinguish between simulated partial- and whole-body irradiations by the u-test, and to accurately estimate the dose from 10-20 Gy, and the initial fraction of irradiated cells in the interval from 10-90%.

Dynamic stability and handling qualities tests on a highly augmented, statically unstable airplane

NASA Technical Reports Server (NTRS)

Gera, Joseph; Bosworth, John T.

1987-01-01

This paper describes some novel flight tests and analysis techniques in the flight dynamics and handling qualities area. These techniques were utilized during the initial flight envelope clearance of the X-29A aircraft and were largely responsible for the completion of the flight controls clearance program without any incidents or significant delays. The resulting open-loop and closed-loop frequency responses and the time history comparison using flight and linear simulation data are discussed.

Modeling of Revitalization of Atmospheric Water

NASA Technical Reports Server (NTRS)

Coker, Robert; Knox, Jim

2014-01-01

The Atmosphere Revitalization Recovery and Environmental Monitoring (ARREM) project was initiated in September of 2011 as part of the Advanced Exploration Systems (AES) program. Under the ARREM project, testing of sub-scale and full-scale systems has been combined with multiphysics computer simulations for evaluation and optimization of subsystem approaches. In particular, this paper describes the testing and modeling of the water desiccant subsystem of the carbon dioxide removal assembly (CDRA). The goal is a full system predictive model of CDRA to guide system optimization and development.

Nanoindentation cannot accurately predict the tensile strength of graphene or other 2D materials

NASA Astrophysics Data System (ADS)

Han, Jihoon; Pugno, Nicola M.; Ryu, Seunghwa

2015-09-01

Due to the difficulty of performing uniaxial tensile testing, the strengths of graphene and its grain boundaries have been measured in experiments by nanoindentation testing. From a series of molecular dynamics simulations, we find that the strength measured in uniaxial simulation and the strength estimated from the nanoindentation fracture force can differ significantly. Fracture in tensile loading occurs simultaneously with the onset of crack nucleation near 5-7 defects, while the graphene sheets often sustain the indentation loads after the crack initiation because the sharply concentrated stress near the tip does not give rise to enough driving force for further crack propagation. Due to the concentrated stress, strength estimation is sensitive to the indenter tip position along the grain boundaries. Also, it approaches the strength of pristine graphene if the tip is located slightly away from the grain boundary line. Our findings reveal the limitations of nanoindentation testing in quantifying the strength of graphene, and show that the loading-mode-specific failure mechanism must be taken into account in designing reliable devices from graphene and other technologically important 2D materials.Due to the difficulty of performing uniaxial tensile testing, the strengths of graphene and its grain boundaries have been measured in experiments by nanoindentation testing. From a series of molecular dynamics simulations, we find that the strength measured in uniaxial simulation and the strength estimated from the nanoindentation fracture force can differ significantly. Fracture in tensile loading occurs simultaneously with the onset of crack nucleation near 5-7 defects, while the graphene sheets often sustain the indentation loads after the crack initiation because the sharply concentrated stress near the tip does not give rise to enough driving force for further crack propagation. Due to the concentrated stress, strength estimation is sensitive to the indenter tip position along the grain boundaries. Also, it approaches the strength of pristine graphene if the tip is located slightly away from the grain boundary line. Our findings reveal the limitations of nanoindentation testing in quantifying the strength of graphene, and show that the loading-mode-specific failure mechanism must be taken into account in designing reliable devices from graphene and other technologically important 2D materials. Electronic ESI (ESI) available: Modelling of polycrystalline graphene, verification of loading speed, biaxial tensile simulations, comparison of stress distribution, size effects of indenter radius, force-deflection curves, and stability analysis of crack propagation. See DOI: 10.1039/c5nr04134a

An investigation of a sterile access technique for the repair and adjustment of sterile spacecraft

NASA Technical Reports Server (NTRS)

Farmer, F. H.; Fuller, H. V.; Hueschen, R. M.

1973-01-01

A description is presented of a unique system for the sterilization and sterile repair of spacecraft and the results of a test program designed to assess the biological integrity and engineering reliability of the system. This trailer-mounted system, designated the model assembly sterilizer for testing (MAST), is capable of the dry-heat sterilization of spacecraft and/or components less than 2.3 meters in diameter at temperatures up to 433 K and the steam sterilization of components less than 0.724 meter in diameter. Sterile access to spacecraft is provided by two tunnel suits, called the bioisolator suit systems (BISS), which are contiguous with the walls of the sterilization chambers. The test program was designed primarily to verify the biological and engineering reliability of the MAST system by processing simulated space hardware. Each test cycle simulated the initial sterilization of a spacecraft, sterile repair of a failed component, removal of the spacecraft from the MAST for mating with the bus, and a sterile recycle repair.

Applications of Computational Methods for Dynamic Stability and Control Derivatives

NASA Technical Reports Server (NTRS)

Green, Lawrence L.; Spence, Angela M.

2004-01-01

Initial steps in the application o f a low-order panel method computational fluid dynamic (CFD) code to the calculation of aircraft dynamic stability and control (S&C) derivatives are documented. Several capabilities, unique to CFD but not unique to this particular demonstration, are identified and demonstrated in this paper. These unique capabilities complement conventional S&C techniques and they include the ability to: 1) perform maneuvers without the flow-kinematic restrictions and support interference commonly associated with experimental S&C facilities, 2) easily simulate advanced S&C testing techniques, 3) compute exact S&C derivatives with uncertainty propagation bounds, and 4) alter the flow physics associated with a particular testing technique from those observed in a wind or water tunnel test in order to isolate effects. Also presented are discussions about some computational issues associated with the simulation of S&C tests and selected results from numerous surface grid resolution studies performed during the course of the study.

Influence of configuration effects on multiple burst simulation testing

NASA Technical Reports Server (NTRS)

Emanuely, J. L.; Cantaloube, M.

1991-01-01

During the initial phase of a lightning strike attachment on an aircraft, fast current pulses (rise time approximately 100 ns, I(sub max) approximately few kA) were measured, which can create equipment upsets or disturbances. This threat, made of repetitive pulses and usually called 'multiple bursts', can be reproduced at the equipment interfaces assuming that the transfer function of the structure was determined. The normalized waveform H (10 kA - 100 ns rise time) is the reference for one of these pulses. The importance of the coaxial return path termination for the injection of the wave H is emphasized. According to the constitutive materials of the test bed, and the adaptation of the line, the natural oscillations of the structure and the internal coupling mechanisms can be modified. As a conclusion, various test configurations in relation with the nature of the test bed and the characteristics of the generator are detailed, for a more accurate ground simulation of the attachment phase.

Simulation's Ensemble is Better Than Ensemble Simulation

NASA Astrophysics Data System (ADS)

Yan, X.

2017-12-01

Simulation's ensemble is better than ensemble simulation Yan Xiaodong State Key Laboratory of Earth Surface Processes and Resource Ecology (ESPRE) Beijing Normal University,19 Xinjiekouwai Street, Haidian District, Beijing 100875, China Email: yxd@bnu.edu.cnDynamical system is simulated from initial state. However initial state data is of great uncertainty, which leads to uncertainty of simulation. Therefore, multiple possible initial states based simulation has been used widely in atmospheric science, which has indeed been proved to be able to lower the uncertainty, that was named simulation's ensemble because multiple simulation results would be fused . In ecological field, individual based model simulation (forest gap models for example) can be regarded as simulation's ensemble compared with community based simulation (most ecosystem models). In this talk, we will address the advantage of individual based simulation and even their ensembles.

Qualitative numerical studies of the modification of the pitch angle distribution of test particles by alfvènic wave activity

NASA Astrophysics Data System (ADS)

Keilbach, D.; Drews, C.; Berger, L.; Marsch, E.; Wimmer-Schweingruber, R. F.

2017-12-01

Using a test particle approach we have investigated, how an oxygen pickup ion torus velocity distribution is modified by continuous and intermittent alfvènic waves on timescales, where the gyro trajectory of each particle can be traced.We have therefore exposed the test particles to mono frequent waves, which expanded through the whole simulation in time and space. The general behavior of the pitch angle distribution is found to be stationary and a nonlinear function of the wave frequency, amplitude and the initial angle between wave elongation and field-perpendicular particle velocity vector. The figure shows the time-averaged pitch angle distributions as a function of the Doppler shifted wave frequency (where the Doppler shift was calculated with respect to the particles initial velocity) for three different wave amplitudes (labeled in each panel). The background field is chosen to be 5 nT and the 500 test particles were initially distributed on a torus with 120° pitch angle at a solar wind velocity of 450 km/s. Each y-slice of the histogram (which has been normalized to it's respective maximum) represents an individual run of the simulation.The frequency-dependent behavior of the test particles is found to be classifiable into the regimes of very low/high frequencies and frequencies close to first order resonance. We have found, that only in the latter regime the particles interact strongly with the wave, where in the time averaged histograms a branch structure is found, which was identified as a trace of particles co-moving with the wave phase. The magnitude of pitch angle change of these particles is as well as the frequency margin, where the branch structure is found, an increasing function with the wave amplitude.We have also investigated the interaction with mono frequent intermittent waves. Exposed to such waves a torus distribution is scattered in pitch angle space, whereas the pitch angle distribution is broadened systematically over time similar to pitch angle diffusion.The framework of our simulations is a first step toward understanding wave particle interactions at the most basic level and is readily expandable to e.g. the inclusion of multiple wave frequencies, intermittent wave activity, gradients in the background magnetic field or collisions with solar wind particles.

Direct model reference adaptive control of robotic arms

NASA Technical Reports Server (NTRS)

Kaufman, Howard; Swift, David C.; Cummings, Steven T.; Shankey, Jeffrey R.

1993-01-01

The results of controlling A PUMA 560 Robotic Manipulator and the NASA shuttle Remote Manipulator System (RMS) using a Command Generator Tracker (CGT) based Model Reference Adaptive Controller (DMRAC) are presented. Initially, the DMRAC algorithm was run in simulation using a detailed dynamic model of the PUMA 560. The algorithm was tuned on the simulation and then used to control the manipulator using minimum jerk trajectories as the desired reference inputs. The ability to track a trajectory in the presence of load changes was also investigated in the simulation. Satisfactory performance was achieved in both simulation and on the actual robot. The obtained responses showed that the algorithm was robust in the presence of sudden load changes. Because these results indicate that the DMRAC algorithm can indeed be successfully applied to the control of robotic manipulators, additional testing was performed to validate the applicability of DMRAC to simulated dynamics of the shuttle RMS.

Benefits of a Unified LaSRS++ Simulation for NAS-Wide and High-Fidelity Modeling

NASA Technical Reports Server (NTRS)

Glaab, Patricia; Madden, Michael

2014-01-01

The LaSRS++ high-fidelity vehicle simulation was extended in 2012 to support a NAS-wide simulation mode. Since the initial proof-of-concept, the LaSRS++ NAS-wide simulation is maturing into a research-ready tool. A primary benefit of this new capability is the consolidation of the two modeling paradigms under a single framework to save cost, facilitate iterative concept testing between the two tools, and to promote communication and model sharing between user communities at Langley. Specific benefits of each type of modeling are discussed along with the expected benefits of the unified framework. Current capability details of the LaSRS++ NAS-wide simulations are provided, including the visualization tool, live data interface, trajectory generators, terminal routing for arrivals and departures, maneuvering, re-routing, navigation, winds, and turbulence. The plan for future development is also described.

Teaching aseptic technique for central venous access under ultrasound guidance: a randomized trial comparing didactic training alone to didactic plus simulation-based training.

PubMed

Latif, Rana K; Bautista, Alexander F; Memon, Saima B; Smith, Elizabeth A; Wang, Chenxi; Wadhwa, Anupama; Carter, Mary B; Akca, Ozan

2012-03-01

Our goal was to determine whether simulation combined with didactic training improves sterile technique during ultrasound (US)-guided central venous catheter (CVC) insertion compared with didactic training alone among novices. We hypothesized that novices who receive combined didactic and simulation-based training would perform similarly to experienced residents in aseptic technique, knowledge, and perception of comfort during US-guided CVC insertion on a simulator. Seventy-two subjects were enrolled in a randomized, controlled trial of an educational intervention. Fifty-four novices were randomized into either the didactic group or the simulation combined with didactic group. Both groups received didactic training but the simulation combined with didactic group also received simulation-based CVC insertion training. Both groups were tested by demonstrating US-guided CVC insertion on a simulator. Aseptic technique was scored on 8 steps as "yes/no" and also using a 7-point Likert scale with 7 being "excellent technique" by a rater blinded to subject randomization. After initial testing, the didactic group was offered simulation-based training and retesting. Both groups also took a pre- and posttraining test of knowledge and rated their comfort with US and CVC insertion pre- and posttraining on a 5-point Likert scale. Subsequently, 18 experienced residents also took the test of knowledge, rated their comfort level, and were scored while performing aseptic US-guided CVC insertion using a simulator. The simulation combined with didactic group achieved a 167% (95% confidence interval [CI] 133%-167%) incremental increase in yes/no scores and 115% (CI 112%-127%) incremental increase in Likert scale ratings on aseptic technique compared with novices in the didactic group. Compared with experienced residents, simulation combined with didactic trained novices achieved an increase in aseptic scores with a 33.3% (CI 16.7%-50%) increase in yes/no ratings and a 20% (CI 13.3%-40%) increase in Likert scaled ratings, and scored 2.5-fold higher on the test of knowledge. There was a 3-fold increase in knowledge and 2-fold increase in comfort level among all novices (P < 0.001) after combined didactic and simulation-based training. Simulation combined with didactic training is superior to didactic training alone for acquisition of clinical skills such as US-guided CVC insertion. After combined didactic and simulation-based training, novices can outperform experienced residents in aseptic technique as well as in measurements of knowledge.

Richardson-Lucy/maximum likelihood image restoration algorithm for fluorescence microscopy: further testing.

PubMed

Holmes, T J; Liu, Y H

1989-11-15

A maximum likelihood based iterative algorithm adapted from nuclear medicine imaging for noncoherent optical imaging was presented in a previous publication with some initial computer-simulation testing. This algorithm is identical in form to that previously derived in a different way by W. H. Richardson "Bayesian-Based Iterative Method of Image Restoration," J. Opt. Soc. Am. 62, 55-59 (1972) and L. B. Lucy "An Iterative Technique for the Rectification of Observed Distributions," Astron. J. 79, 745-765 (1974). Foreseen applications include superresolution and 3-D fluorescence microscopy. This paper presents further simulation testing of this algorithm and a preliminary experiment with a defocused camera. The simulations show quantified resolution improvement as a function of iteration number, and they show qualitatively the trend in limitations on restored resolution when noise is present in the data. Also shown are results of a simulation in restoring missing-cone information for 3-D imaging. Conclusions are in support of the feasibility of using these methods with real systems, while computational cost and timing estimates indicate that it should be realistic to implement these methods. Itis suggested in the Appendix that future extensions to the maximum likelihood based derivation of this algorithm will address some of the limitations that are experienced with the nonextended form of the algorithm presented here.

Initial investigation of the corrosion stability of craniofacial implants.

PubMed

Beline, Thamara; Vechiato Filho, Aljomar José; Wee, Alvin G; Sukotjo, Cortino; Dos Santos, Daniela Micheline; Brandão, Thaís Bianca; Barão, Valentim Adelino Ricardo

2018-01-01

Although craniofacial implants have been used for retention of facial prostheses, failures are common. Titanium undergoes corrosion in the oral cavity, but the corrosion of craniofacial implants requires evaluation. The purpose of this in vitro study was to investigate the corrosion stability of commercially pure titanium (CP Ti) exposed to simulated human perspiration at 2 different pH levels (5.5 and 8). Fifteen titanium disks were divided into 3 groups (n=5 per group). The control group was subjected to simulated body fluid (SBF) (control). Disks from the 2 experimental groups were immersed in simulated alkaline perspiration (SA K P) and simulated acidic perspiration (SA C P). Electrochemical tests, including open circuit potential (3600 seconds), electrochemical impedance spectroscopy, and potentiodynamic tests were performed according to the standardized method of 3-cell electrodes. Data were analyzed by 1-way ANOVA and the Tukey honestly significant difference tests (α=.05). Simulated human perspiration reduced the corrosion stability of CP Ti (P<.05). The SBF group presented the lowest capacitance values (P<.05). SA K P and SA C P groups showed increased values of capacitance and showed no statistically significant differences (P>.05) from each other. The increase in capacitance suggests that the acceleration of the ionic exchanges between the CP Ti and the electrolyte leads to a lower corrosion resistance. SA K P reduced the oxide layer resistance of CP Ti (P<.05), and an increased corrosion rate was noted in both simulated human perspiration groups. Craniofacial implants can corrode when in contact with simulated human perspiration, whereas alkaline perspiration shows a more deleterious effect. Perspiration induces a more corrosive effect than simulated body fluid. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Two-way coupling of magnetohydrodynamic simulations with embedded particle-in-cell simulations

NASA Astrophysics Data System (ADS)

Makwana, K. D.; Keppens, R.; Lapenta, G.

2017-12-01

We describe a method for coupling an embedded domain in a magnetohydrodynamic (MHD) simulation with a particle-in-cell (PIC) method. In this two-way coupling we follow the work of Daldorff et al. (2014) [19] in which the PIC domain receives its initial and boundary conditions from MHD variables (MHD to PIC coupling) while the MHD simulation is updated based on the PIC variables (PIC to MHD coupling). This method can be useful for simulating large plasma systems, where kinetic effects captured by particle-in-cell simulations are localized but affect global dynamics. We describe the numerical implementation of this coupling, its time-stepping algorithm, and its parallelization strategy, emphasizing the novel aspects of it. We test the stability and energy/momentum conservation of this method by simulating a steady-state plasma. We test the dynamics of this coupling by propagating plasma waves through the embedded PIC domain. Coupling with MHD shows satisfactory results for the fast magnetosonic wave, but significant distortion for the circularly polarized Alfvén wave. Coupling with Hall-MHD shows excellent coupling for the whistler wave. We also apply this methodology to simulate a Geospace Environmental Modeling (GEM) challenge type of reconnection with the diffusion region simulated by PIC coupled to larger scales with MHD and Hall-MHD. In both these cases we see the expected signatures of kinetic reconnection in the PIC domain, implying that this method can be used for reconnection studies.

James Webb Space Telescope (JWST) Integrated Science Instruments Module (ISIM) Cryo-Vacuum (CV) Test Campaign Summary

NASA Technical Reports Server (NTRS)

Yew, Calinda; Lui, Yan; Whitehouse, Paul; Banks, Kimberly

2016-01-01

JWST Integrated Science Instruments Module (ISIM) completed its system-level space simulation testing program at the NASA Goddard Space Flight Center (GSFC). In March 2016, ISIM was successfully delivered to the next level of integration with the Optical Telescope Element (OTE), to form OTIS (OTE + ISIM), after concluding a series of three cryo-vacuum (CV) tests. During these tests, the complexity of the mission has generated challenging requirements that demand highly reliable system performance and capabilities from the Space Environment Simulator (SES) vacuum chamber. The first test served as a risk reduction test; the second test provided the initial verification of the fully-integrated flight instruments; and the third test verified the system in its final flight configuration following mechanical environmental tests (vibration and acoustics). From one test to the next, shortcomings of the facility were uncovered and associated improvements in operational capabilities and reliability of the facility were required to enable the project to verify system-level requirements. This paper: (1) provides an overview of the integrated mechanical and thermal facility systems required to achieve the objectives of JWST ISIM testing, (2) compares the overall facility performance and instrumentation results from the three ISIM CV tests, and (3) summarizes lessons learned from the ISIM testing campaign.

A Simulation Based Investigation of High Latency Space Systems Operations

NASA Technical Reports Server (NTRS)

Li, Zu Qun; Moore, Michael; Bielski, Paul; Crues, Edwin Z.

2017-01-01

This study was the first in a series of planned tests to use physics-based subsystem simulations to investigate the interactions between a spacecraft's crew and a ground-based mission control center for vehicle subsystem operations across long communication delays. The simulation models the life support system of a deep space habitat. It contains models of an environmental control and life support system, an electrical power system, an active thermal control systems, and crew metabolic functions. The simulation has three interfaces: 1) a real-time crew interface that can be use to monitor and control the subsystems; 2) a mission control center interface with data transport delays up to 15 minute each way; and 3) a real-time simulation test conductor interface used to insert subsystem malfunctions and observe the interactions between the crew, ground, and simulated vehicle. The study was conducted at the 21st NASA Extreme Environment Mission Operations (NEEMO) mission. The NEEMO crew and ground support team performed a number of relevant deep space mission scenarios that included both nominal activities and activities with system malfunctions. While this initial test sequence was focused on test infrastructure and procedures development, the data collected in the study already indicate that long communication delays have notable impacts on the operation of deep space systems. For future human missions beyond cis-lunar, NASA will need to design systems and support tools to meet these challenges. These will be used to train the crew to handle critical malfunctions on their own, to predict malfunctions and assist with vehicle operations. Subsequent more detailed and involved studies will be conducted to continue advancing NASA's understanding of space systems operations across long communications delays.

A Simulation Based Investigation of High Latency Space Systems Operations

NASA Technical Reports Server (NTRS)

Li, Zu Qun; Crues, Edwin Z.; Bielski, Paul; Moore, Michael

2017-01-01

This study was the first in a series of planned tests to use physics-based subsystem simulations to investigate the interactions between a spacecraft's crew and a ground-based mission control center for vehicle subsystem operations across long communication delays. The simulation models the life support system of a deep space habitat. It contains models of an environmental control and life support system, an electrical power system, an active thermal control system, and crew metabolic functions. The simulation has three interfaces: 1) a real-time crew interface that can be use to monitor and control the subsystems; 2) a mission control center interface with data transport delays up to 15 minute each way; and 3) a real-time simulation test conductor interface used to insert subsystem malfunctions and observe the interactions between the crew, ground, and simulated vehicle. The study was conducted at the 21st NASA Extreme Environment Mission Operations (NEEMO) mission. The NEEMO crew and ground support team performed a number of relevant deep space mission scenarios that included both nominal activities and activities with system malfunctions. While this initial test sequence was focused on test infrastructure and procedures development, the data collected in the study already indicate that long communication delays have notable impacts on the operation of deep space systems. For future human missions beyond cis-lunar, NASA will need to design systems and support tools to meet these challenges. These will be used to train the crew to handle critical malfunctions on their own, to predict malfunctions, and to assist with vehicle operations. Subsequent more detailed and involved studies will be conducted to continue advancing NASA's understanding of space systems operations across long communications delays.

In vitro dynamic solubility test: influence of various parameters.

PubMed Central

Thélohan, S; de Meringo, A

1994-01-01

This article discusses the dissolution of mineral fibers in simulated physiological fluids (SPF), and the parameters that affect the solubility measurement in a dynamic test where an SPF runs through a cell containing fibers (Scholze and Conradt test). Solutions simulate either the extracellular fluid (pH 7.6) or the intracellular fluid (pH 4.5). The fibers have various chemical compositions and are either continuously drawn or processed as wool. The fiber solubility is determined by the amount of SiO2 (and occasionally other ions) released in the solution. Results are stated as percentage of the initial silica content released or as dissolution rate v in nm/day. The reproducibility of the test is higher with the less soluble fibers (10% solubility), than with highly soluble fibers (20% solubility). The influence of test parameters, including SPF, test duration, and surface area/volume (SA/V), has been studied. The pH and the inorganic buffer salts have a major influence: industrial glasswool composition is soluble at pH 7.6 but not at pH 4.5. The opposite is true for rock- (basalt) wool composition. For slightly soluble fibers, the dissolution rate v remains constant with time, whereas for highly soluble fibers, the dissolution rate decreases rapidly. The dissolution rates believed to occur are v1, initial dissolution rate, and v2, dissolution rate of the residual fibers. The SA of fibers varies with the mass of the fibers tested, or with the fiber diameter at equal mass. Volume, V, is the chosen flow rate. An increase in the SA/V ratio leads to a decrease in the dissolution rate.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7882964

In vitro dynamic solubility test: influence of various parameters.

PubMed

Thélohan, S; de Meringo, A

1994-10-01

This article discusses the dissolution of mineral fibers in simulated physiological fluids (SPF), and the parameters that affect the solubility measurement in a dynamic test where an SPF runs through a cell containing fibers (Scholze and Conradt test). Solutions simulate either the extracellular fluid (pH 7.6) or the intracellular fluid (pH 4.5). The fibers have various chemical compositions and are either continuously drawn or processed as wool. The fiber solubility is determined by the amount of SiO2 (and occasionally other ions) released in the solution. Results are stated as percentage of the initial silica content released or as dissolution rate v in nm/day. The reproducibility of the test is higher with the less soluble fibers (10% solubility), than with highly soluble fibers (20% solubility). The influence of test parameters, including SPF, test duration, and surface area/volume (SA/V), has been studied. The pH and the inorganic buffer salts have a major influence: industrial glasswool composition is soluble at pH 7.6 but not at pH 4.5. The opposite is true for rock- (basalt) wool composition. For slightly soluble fibers, the dissolution rate v remains constant with time, whereas for highly soluble fibers, the dissolution rate decreases rapidly. The dissolution rates believed to occur are v1, initial dissolution rate, and v2, dissolution rate of the residual fibers. The SA of fibers varies with the mass of the fibers tested, or with the fiber diameter at equal mass. Volume, V, is the chosen flow rate. An increase in the SA/V ratio leads to a decrease in the dissolution rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Polymethylmethacrylate combustion in a narrow channel apparatus simulating a microgravity environment

NASA Astrophysics Data System (ADS)

Bornand, Garrett Randall

Fire safety is an important part of engineering when human lives are at stake. From everyday homes to spacecraft that can cost hundreds of millions of dollars. The research in this thesis attempts to provide scientific evidence that the apparatus in question successfully simulates microgravity and can possibly replace NASA's current test method for spacecraft fire safety. Flame spread tests were conducted with thermally thick and thermally thin polymethylmethacrylate (PMMA) samples to study flame spread behavior in response to environmental changes. The tests were conducted using the San Diego State University Narrow Channel Apparatus (SDSU NCA) as well as within the Microgravity Science Glovebox (MSG) on the International Space Station (ISS). The SDSU NCA can suppress buoyant flow in horizontally spreading flames, and is currently being investigated as a possible replacement or complement to NASA's current material flammability test standard for non-metallic solids, NASA-STD-(I)-6001B Test 1. The buoyant suppression attained in the NCA allows tests to be conducted in a simulated microgravity environment-a characteristic that NASA's Test 1 lacks since flames present in Test 1 are driven by buoyant flows. The SDSU NCA allows for tests to be conducted at various opposed flow oxidizer velocities, oxygen percent by volume, and total pressure to mimic various spacecraft and habitat atmospheres. Tests were conducted at 1 atm pressure, thin fuel thickness of 50 and 75 microns, thick fuel thickness ranging from 3 mm to 5.6 mm, opposed oxidizer velocity ranging from 10 to 25 cm/s, and oxygen concentration by volume at 21, 30, and 50 percent. The simulated microgravity flame spread results were then compared to true microgravity experiments including; testing conducted on the International Space Station (ISS) under the Burning and Suppression of Solids (BASS) research, NASA's 5.2 second Drop Tower, and Micro-Gravity Laboratory's (MGLAB) 4.5 second Drop Tower. Data was also compared to results found by Michigan State University's NCA. Flame spread results from the SDSU NCA compare closely to that of the other experimental techniques. Additionally, an infrared camera and species concentration sensors were added to the SDSU NCA and initial results are provided. Fire Dynamics Simulator (FDS) was used to model the combustion of PMMA within the SDSU NCA. Both thin and thick fuel beds were simulated and the numerical results were compared to experimental data. The simulation was then used to determine various results that cannot easily be found with experimentation, including how effectively the NCA simulates microgravity under certain environmental conditions, gas and fuel bed temperatures, heat fluxes, species concentrations, pyrolysis rate, and other various data. The simulation was found to give reasonable results and overall flame spread trends, but could be improved upon with further detailed kinetic parameter studies.

Waterhammer Transient Simulation and Model Anchoring for the Robotic Lunar Lander Propulsion System

NASA Technical Reports Server (NTRS)

Stein, William B.; Trinh, Huu P.; Reynolds, Michael E.; Sharp, David J.

2011-01-01

Waterhammer transients have the potential to adversely impact propulsion system design if not properly addressed. Waterhammer can potentially lead to system plumbing, and component damage. Multi-thruster propulsion systems also develop constructive/destructive wave interference which becomes difficult to predict without detailed models. Therefore, it is important to sufficiently characterize propulsion system waterhammer in order to develop a robust design with minimal impact to other systems. A risk reduction activity was performed at Marshall Space Flight Center to develop a tool for estimating waterhammer through the use of anchored simulation for the Robotic Lunar Lander (RLL) propulsion system design. Testing was performed to simulate waterhammer surges due to rapid valve closure and consisted of twenty-two series of waterhammer tests, resulting in more than 300 valve actuations. These tests were performed using different valve actuation schemes and three system pressures. Data from the valve characterization tests were used to anchor the models that employed MSCSoftware.EASY5 v.2010 to model transient fluid phenomena by using transient forms of mass and energy conservation. The anchoring process was performed by comparing initial model results to experimental data and then iterating the model input to match the simulation results with the experimental data. The models provide good correlation with experimental results, supporting the use of EASY5 as a tool to model fluid transients and provide a baseline for future RLL system modeling. This paper addresses tasks performed during the waterhammer risk reduction activity for the RLL propulsion system. The problem of waterhammer simulation anchoring as applied to the RLL system is discussed with results from the corresponding experimental valve tests. Important factors for waterhammer mitigation are discussed along with potential design impacts to the RLL propulsion system.

Continuum damage modeling and simulation of hierarchical dental enamel

NASA Astrophysics Data System (ADS)

Ma, Songyun; Scheider, Ingo; Bargmann, Swantje

2016-05-01

Dental enamel exhibits high fracture toughness and stiffness due to a complex hierarchical and graded microstructure, optimally organized from nano- to macro-scale. In this study, a 3D representative volume element (RVE) model is adopted to study the deformation and damage behavior of the fibrous microstructure. A continuum damage mechanics model coupled to hyperelasticity is developed for modeling the initiation and evolution of damage in the mineral fibers as well as protein matrix. Moreover, debonding of the interface between mineral fiber and protein is captured by employing a cohesive zone model. The dependence of the failure mechanism on the aspect ratio of the mineral fibers is investigated. In addition, the effect of the interface strength on the damage behavior is studied with respect to geometric features of enamel. Further, the effect of an initial flaw on the overall mechanical properties is analyzed to understand the superior damage tolerance of dental enamel. The simulation results are validated by comparison to experimental data from micro-cantilever beam testing at two hierarchical levels. The transition of the failure mechanism at different hierarchical levels is also well reproduced in the simulations.

Impacts of dynamical ocean coupling in MJO experiments using NICAM/NICOCO

NASA Astrophysics Data System (ADS)

Miyakawa, T.

2016-12-01

The cloud-system resolving atmosphereic model NICAM has been successfull in producing Madden-Julian Oscillations(MJOs), having it's prediction skill estimated to be about 4 weeks in a series of hindcast experiments for winter MJO events during 2003-2012 (Miyakawa et al. 2014). A simple mixed-layer ocean model has been applied with nudging towards a prescribed "persistent anomaly SST", which maintains the initial anomaly with a time-varying climatological seasonal cycle. This setup enables the model to interact with an ocean with reasonably realistic SST, and also run in a "forecast mode", without using any observational information after the initial date. A limitation is that under this setup, the model skill drops if the oceanic anomaly rapidly changes after the initial date in the real world. Here we run a recently developed, full 3D-ocean coupled version NICAM-COCO (NICOCO) and explore its impact on MJO simulations. Dynamical ocean models can produce oceanic waves/currents, but will also have a bias and drift away from reality. In a sub-seasonal simulation (an initial problem), it is essential to compare the merit of having better represented oceanic signals and the demerit of bias/drift. A test case simulation series featuring an MJO that triggered the abrupt termination of a major El Nino in 1998 shows that the abrupt termination occurs in all 9 simulation members, highlighting the merit of ocean coupling. However, this is a case where oceanic signals are at its extremes. We carried out an estimation of MJO prediction skill for a preliminary 1-degree mesh ocean version of NICOCO in a similar manner to Miyakawa et al. (2014). The MJO skill was degraded for simulations that was initialized at RMM phases 1 and 2 (corresponding to the Indian Ocean), while those initialized at phase 8 (Africa) was not strongly affected. The tendency of the model ocean to overestimate the Maritime Continent warm pool SST possibly delays the eastward propagation of MJO convective envelope, accounting for the degrade of prediction skills (phases 1 and 2). Reference:Madden-Julian Oscillation prediction skill of a new-generation global model demonstrated using a supercomputer. Miyakawa, T., M. Satoh, H. Miura, H. Tomita, H. Yashiro, A. T. Noda, Y. Yamada, C. Kodama, M. Kimoto & K. Yoneyama. Nature Comm. 5, 3769, doi:10.1038/ncomms4769.

Testing a one-dimensional prescription of dynamical shear mixing with a two-dimensional hydrodynamic simulation

NASA Astrophysics Data System (ADS)

Edelmann, P. V. F.; Röpke, F. K.; Hirschi, R.; Georgy, C.; Jones, S.

2017-07-01

Context. The treatment of mixing processes is still one of the major uncertainties in 1D stellar evolution models. This is mostly due to the need to parametrize and approximate aspects of hydrodynamics in hydrostatic codes. In particular, the effect of hydrodynamic instabilities in rotating stars, for example, dynamical shear instability, evades consistent description. Aims: We intend to study the accuracy of the diffusion approximation to dynamical shear in hydrostatic stellar evolution models by comparing 1D models to a first-principle hydrodynamics simulation starting from the same initial conditions. Methods: We chose an initial model calculated with the stellar evolution code GENEC that is just at the onset of a dynamical shear instability but does not show any other instabilities (e.g., convection). This was mapped to the hydrodynamics code SLH to perform a 2D simulation in the equatorial plane. We compare the resulting profiles in the two codes and compute an effective diffusion coefficient for the hydro simulation. Results: Shear instabilities develop in the 2D simulation in the regions predicted by linear theory to become unstable in the 1D stellar evolution model. Angular velocity and chemical composition is redistributed in the unstable region, thereby creating new unstable regions. After a period of time, the system settles in a symmetric, steady state, which is Richardson stable everywhere in the 2D simulation, whereas the instability remains for longer in the 1D model due to the limitations of the current implementation in the 1D code. A spatially resolved diffusion coefficient is extracted by comparing the initial and final profiles of mean atomic mass. Conclusions: The presented simulation gives a first insight on hydrodynamics of shear instabilities in a real stellar environment and even allows us to directly extract an effective diffusion coefficient. We see evidence for a critical Richardson number of 0.25 as regions above this threshold remain stable for the course of the simulation. The movie of the simulation is available at http://www.aanda.org

Impact-initiated damage thresholds in composites

NASA Technical Reports Server (NTRS)

Sharma, A. V.

1980-01-01

An experimental investigation was conducted to study the effect of low velocity projectile impact on the sandwich-type structural components. The materials used in the fabrication of the impact surface were graphite-, Kevlar-, and boron-fibers with appropriate epoxy matrices. The testing of the specimens was performed at moderately low- and high-temperatures as well as at room temperature to assess the impact-initiated strength degradation of the laminates. Eleven laminates with different stacking sequences, orientations, and thicknesses were tested. The low energy projectile impact is considered to simulate the damage caused by runway debris, dropping of the hand tools during servicing, etc., on the secondary aircraft structures fabricated with the composite materials. The results show the preload and the impact energy combinations necessary to cause catastrophic failures in the laminates tested. A set of faired curves indicating the failure thresholds is shown separately for the tension- and compression-loaded laminates. The specific-strengths and -moduli for the various laminates tested are also given.

RQL Sector Rig Testing of SiC/SiC Combustor Liners

NASA Technical Reports Server (NTRS)

Verrilli, Michael J.; Martin, Lisa C.; Brewer, David N.

2002-01-01

Combustor liners, manufactured from silicon carbide fiber-reinforced silicon carbide (SiC/SiC) were tested for 260 hr using a simulated gas turbine engine cycle. This report documents the results of the last 56 hr of testing. Damage occurred in one of the six different components that make up the combustor liner set, the rich zone liner. Cracks in the rich zone liner initiated at the leading edge due to stresses resulting from the component attachment configuration. Thin film thermocouples and fiber optic pyrometers were used to measure the rich zone liner's temperature and these results are reported.

History of the numerical aerodynamic simulation program

NASA Technical Reports Server (NTRS)

Peterson, Victor L.; Ballhaus, William F., Jr.

1987-01-01

The Numerical Aerodynamic Simulation (NAS) program has reached a milestone with the completion of the initial operating configuration of the NAS Processing System Network. This achievement is the first major milestone in the continuing effort to provide a state-of-the-art supercomputer facility for the national aerospace community and to serve as a pathfinder for the development and use of future supercomputer systems. The underlying factors that motivated the initiation of the program are first identified and then discussed. These include the emergence and evolution of computational aerodynamics as a powerful new capability in aerodynamics research and development, the computer power required for advances in the discipline, the complementary nature of computation and wind tunnel testing, and the need for the government to play a pathfinding role in the development and use of large-scale scientific computing systems. Finally, the history of the NAS program is traced from its inception in 1975 to the present time.

Measurements in liquid fuel sprays

NASA Technical Reports Server (NTRS)

Chigier, N.; Mao, C. P.

1985-01-01

A ground test facility is being established at NASA Lewis Research Center to simulate the environmental and flight conditions needed to study adverse weather effects. One of the most important components is the water spray system which consists of many nozzles fitted on spray bars. Water is injected through air-assisted atomizers to generate uniform size drops to simulate icing in clouds. The primary objective is to provide experimental data on drop size distribution over a wide range of operating conditions. Correlation equations for mean drop size and initial injection parameters are being determined to assist in the design and modification of the Altitude Wind Tunnel. Special emphasis is being placed on the study of the aerodynamic structure of the air-assisted atomizer sprays. Detailed measurements of the variation of drop size distribution and velocity as a function of time and space are being made. Accurate initial and boundary conditions are being provided for computer model evaluation.

Experiences in using DISCUS for visualizing human communication

NASA Astrophysics Data System (ADS)

Groehn, Matti; Nieminen, Marko; Haho, Paeivi; Smeds, Riitta

2000-02-01

In this paper, we present further improvement to the DISCUS software that can be used to record and analyze the flow and constants of business process simulation session discussion. The tool was initially introduced in 'visual data exploration and analysis IV' conference. The initial features of the tool enabled the visualization of discussion flow in business process simulation sessions and the creation of SOM analyses. The improvements of the tool consists of additional visualization possibilities that enable quick on-line analyses and improved graphical statistics. We have also created the very first interface to audio data and implemented two ways to visualize it. We also outline additional possibilities to use the tool in other application areas: these include usability testing and the possibility to use the tool for capturing design rationale in a product development process. The data gathered with DISCUS may be used in other applications, and further work may be done with data ming techniques.

Nonspecialty Nurse Education: Evaluation of the Oncology Intensives Initiative, an Oncology Curriculum to Improve Patient Care

PubMed

Bagley, Kimberly A; Dunn, Sarah E; Chuang, Eliseu Y; Dorr, Victoria J; Thompson, Julie A; Smith, Sophia K

2018-04-01

A community hospital combined its medical and surgical patients with cancer on one unit, which resulted in nurses not trained in oncology caring for this patient population. The Oncology Intensives Initiative (ONCii) involved the (a) design and implementation of a daylong didactic boot camp class and a four-hour simulation session and (b) the examination of nurses' worries, attitudes, self-efficacy, and perception of interdisciplinary teamwork. A two-group, pre-/post-test design was implemented. Group 1 consisted of nurses who attended the didactic boot camp classes alone, whereas group 2 was comprised of nurses who attended the didactic boot camp classes and the simulation sessions. Results of data analysis showed a decrease in worries and an increase in positive attitudes toward chemotherapy administration in both groups, as well as an increase in self-efficacy among members of group 2.

Polar Ozone Loss Rates: Comparison Of Match Observations With Simulations Of 3-D Chemical Transport Model And Box Model

NASA Astrophysics Data System (ADS)

Tripathi, O. P.; Godin-Beekmann, S.; Lefevre, F.; Marchand, M.; Pazmino, A.; Hauchecorne, A.

2005-12-01

Model simulations of ozone loss rates during recent arctic and Antarctic winters are compared with the observed ozone loss rates from the match technique. Arctic winters 1994/1995, 1999/2000, 2002/2003 and the Antarctic winter 2003 were considered for the analysis. We use a high resolution chemical transport model MIMOSA-CHIM and REPROBUS box model for the calculation of ozone loss rates. Trajectory model calculations show that the ozone loss rates are dependent on the initialization fields. On the one hand when chemical fields are initialized by UCAM (University of Cambridge SLIMCAT model simulated fields) the loss rates were underestimated by a factor of two whereas on the other hand when it is initialized by UL (University of Leeds) fields the model loss rates are in a very good agreement with match loss rates at lower levels. The study shows a very good agreement between MIMOSA-CHIM simulation and match observation in 1999/2000 winter at both levels, 450 and 500 K, except slight underestimation in March at 500 K. But in January we have a very good agreement. This is also true for 1994/1995 when we consider simulated ozone loss rate in view of the ECMWF wind deficiency assuming that match observations were not made on isolated trajectories. Sensitivity tests, by changing JCl2O2 value, particle number density and heating rates, performed for the arctic winter 1999/2000 shows that we need to improve our understanding of particle number density and heating rate calculation mechanism. Burkholder JCl2O2 has improved the comparison of MIMOSA-CHIM model results with observations (Tripathi et al., 2005). In the same study the comparison results were shown to improved by changing heating rates and number density through NAT particle sedimentation.

Three Dimensional Numerical Simulation of Rocket-based Combined-cycle Engine Response During Mode Transition Events

NASA Technical Reports Server (NTRS)

Edwards, Jack R.; McRae, D. Scott; Bond, Ryan B.; Steffan, Christopher (Technical Monitor)

2003-01-01

The GTX program at NASA Glenn Research Center is designed to develop a launch vehicle concept based on rocket-based combined-cycle (RBCC) propulsion. Experimental testing, cycle analysis, and computational fluid dynamics modeling have all demonstrated the viability of the GTX concept, yet significant technical issues and challenges still remain. Our research effort develops a unique capability for dynamic CFD simulation of complete high-speed propulsion devices and focuses this technology toward analysis of the GTX response during critical mode transition events. Our principal attention is focused on Mode 1/Mode 2 operation, in which initial rocket propulsion is transitioned into thermal-throat ramjet propulsion. A critical element of the GTX concept is the use of an Independent Ramjet Stream (IRS) cycle to provide propulsion at Mach numbers less than 3. In the IRS cycle, rocket thrust is initially used for primary power, and the hot rocket plume is used as a flame-holding mechanism for hydrogen fuel injected into the secondary air stream. A critical aspect is the establishment of a thermal throat in the secondary stream through the combination of area reduction effects and combustion-induced heat release. This is a necessity to enable the power-down of the rocket and the eventual shift to ramjet mode. Our focus in this first year of the grant has been in three areas, each progressing directly toward the key initial goal of simulating thermal throat formation during the IRS cycle: CFD algorithm development; simulation of Mode 1 experiments conducted at Glenn's Rig 1 facility; and IRS cycle simulations. The remainder of this report discusses each of these efforts in detail and presents a plan of work for the next year.

Comparison of Analytical Predictions and Experimental Results for a Dual Brayton Power System

NASA Technical Reports Server (NTRS)

Johnson, Paul

2007-01-01

NASA Glenn Research Center (GRC) contracted Barber- Nichols, Arvada, CO to construct a dual Brayton power conversion system for use as a hardware proof of concept and to validate results from a computational code known as the Closed Cycle System Simulation (CCSS). Initial checkout tests were performed at Barber- Nichols to ready the system for delivery to GRC. This presentation describes the system hardware components and lists the types of checkout tests performed along with a couple issues encountered while conducting the tests. A description of the CCSS model is also presented. The checkout tests did not focus on generating data, therefore, no test data or model analyses are presented.

Ares I-X USS Material Testing

NASA Technical Reports Server (NTRS)

Dawicke, David S.; Smith, Stephen W.; Raju, Ivatury S.

2008-01-01

An independent assessment was conducted to determine the critical initial flaw size (CIFS) for the flange-to-skin weld in the Ares I-X Upper Stage Simulator (USS). Material characterization tests were conducted to quantify the material behavior for use in the CIFS analyses. Fatigue crack growth rate, Charpy impact, and fracture tests were conducted on the parent and welded A516 Grade 70 steel. The crack growth rate tests confirmed that the material behaved in agreement with literature data and that a salt water environment would not significantly degrade the fatigue resistance. The Charpy impact tests confirmed that the fracture resistance of the material did not have a significant reduction for the expected operational temperatures of the vehicle.

Implementation of STUD Pulses at the Trident Laser and Initial Results

NASA Astrophysics Data System (ADS)

Johnson, R. P.; Shimada, T.; Montgomery, D. S.; Afeyan, B.; Hüller, S.

2012-10-01

Controlling and mitigating laser-plasma instabilities such as stimulated Brillouin scattering, stimulated Raman scattering, and crossed-beam energy transfer is important to achieve high-gain inertial fusion using laser drivers. Recent theory and simulations show that these instabilities can be largely controlled using laser pulses consisting of spike trains of uneven duration and delay (STUD) by modulating the laser on a picosecond time scale [1,2]. We have designed and implemented a STUD pulse generator at the LANL Trident Laser Facility using Fourier synthesis to produce a 0.5-ns envelope of psec-duration STUD pulses using a spatial light modulator. Initial results from laser propagation tests and measurements as well as initial laser-plasma characterization experiments will be presented.[4pt] [1] B. Afeyan and S. H"uller, ``Optimal Control of Laser Plasma Instabilities using STUD pulses,'' IFSA 2011, P.Mo.1, to appear in Euro. Phys. J. Web of Conf. (2012).[2] S. H"uller and B. Afeyan, ``Simulations of drastically reduced SBS with STUD pulses,'' IFSA 2011, O.Tu8-1, to appear in Euro. Phys. J. Web of Conf. (2012).

The Effects of a Duathlon Simulation on Ventilatory Threshold and Running Economy

PubMed Central

Berry, Nathaniel T.; Wideman, Laurie; Shields, Edgar W.; Battaglini, Claudio L.

2016-01-01

Multisport events continue to grow in popularity among recreational, amateur, and professional athletes around the world. This study aimed to determine the compounding effects of the initial run and cycling legs of an International Triathlon Union (ITU) Duathlon simulation on maximal oxygen uptake (VO2max), ventilatory threshold (VT) and running economy (RE) within a thermoneutral, laboratory controlled setting. Seven highly trained multisport athletes completed three trials; Trial-1 consisted of a speed only VO2max treadmill protocol (SOVO2max) to determine VO2max, VT, and RE during a single-bout run; Trial-2 consisted of a 10 km run at 98% of VT followed by an incremental VO2max test on the cycle ergometer; Trial-3 consisted of a 10 km run and 30 km cycling bout at 98% of VT followed by a speed only treadmill test to determine the compounding effects of the initial legs of a duathlon on VO2max, VT, and RE. A repeated measures ANOVA was performed to determine differences between variables across trials. No difference in VO2max, VT (%VO2max), maximal HR, or maximal RPE was observed across trials. Oxygen consumption at VT was significantly lower during Trial-3 compared to Trial-1 (p = 0.01). This decrease was coupled with a significant reduction in running speed at VT (p = 0.015). A significant interaction between trial and running speed indicate that RE was significantly altered during Trial-3 compared to Trial-1 (p < 0.001). The first two legs of a laboratory based duathlon simulation negatively impact VT and RE. Our findings may provide a useful method to evaluate multisport athletes since a single-bout incremental treadmill test fails to reveal important alterations in physiological thresholds. Key points Decrease in relative oxygen uptake at VT (ml·kg-1·min-1) during the final leg of a duathlon simulation, compared to a single-bout maximal run. We observed a decrease in running speed at VT during the final leg of a duathlon simulation; resulting in an increase of more than 2 minutes to complete a 5 km run. During our study, highly trained athletes were unable to complete the final 5 km run at the same intensity that they completed the initial 10 km run (in a laboratory setting). A better understanding, and determination, of training loads during multisport training may help to better periodize training programs; additional research is required. PMID:27274661

Morphological Differentiation of Colon Carcinoma Cell Lines in Rotating Wall Vessels

NASA Technical Reports Server (NTRS)

Jessup, J. M.

1994-01-01

The objectives of this project were to determine whether (1) microgravity permits unique, three-dimensional cultures of neoplastic human colon tissues and (2) this culture interaction produces novel intestinal growth and differentiation factors. The initial phase of this project tested the efficacy of simulated microgravity for the cultivation and differentiation of human colon carcinoma in rotating wall vessels (RWV's) on microcarrier beads. The RWV's simulate microgravity by randomizing the gravity vector in an aqueous medium under a low shear stress environment in unit gravity. This simulation achieves approximately a one-fifth g environment that allows cells to 'float' and form three-dimensional relationships with less shear stress than in other stirred aqueous medium bioreactors. In the second phase of this project we assessed the ability of human colon carcinoma lines to adhere to various substrates because adhesion is the first event that must occur to create three-dimensional masses. Finally, we tested growth factor production in the last phase of this project.

Comparative analysis of international standards for the fatigue testing of posterior spinal fixation systems: the importance of preload in ISO 12189.

PubMed

La Barbera, Luigi; Ottardi, Claudia; Villa, Tomaso

2015-10-01

Preclinical evaluation of the mechanical reliability of fixation devices is a mandatory activity before their introduction into market. There are two standardized protocols for preclinical testing of spinal implants. The American Society for Testing Materials (ASTM) recommends the F1717 standard, which describes a vertebrectomy condition that is relatively simple to implement, whereas the International Organization for Standardization (ISO) suggests the 12189 standard, which describes a more complex physiological anterior support-based setup. Moreover, ASTM F1717 is nowadays well established, whereas ISO 12189 has received little attention: A few studies tried to accurately describe the ISO experimental procedure through numeric models, but these studies totally neglect the recommended precompression step. This study aimed to build up a reliable, validated numeric model capable of describing the stress on the rods of a spinal fixator assembled according to ISO 12189 standard procedure. Such a model would more adequately represent the in vitro testing condition. This study used finite element (FE) simulations and experimental validation testing. An FE model of the ISO setup was built to calculate the stress on the rods. Simulation was validated by comparison with experimental strain gauges measurements. The same fixator has been previously virtually mounted in an L2-L4 FE model of the lumbar spine, and stresses in the rods were calculated when the spine was subjected to physiological forces and moments. The comparison between the FE predictions and experimental measurements is in good agreement, thus confirming the suitability of the FE method to evaluate the stresses in the device. The initial precompression induces a significant extension of the assembled construct. As the applied load increases, the initial extension is gradually compensated, so that at peak load the rods are bent in flexion: The final stress value predicted is thus reduced to about 50%, if compared with the previous model where the precompression was not considered. Neglecting the initial preload due to the assembly of the overall construct according to ISO 12189 standard could lead to an overestimation of the stress on the rods up to 50%. To correctly describe the state of stress on the posterior spinal fixator, tested according to the ISO procedure, it is important to take into account the initial preload due to the assembly of the overall construct. Copyright © 2015 Elsevier Inc. All rights reserved.

Numerical simulation of lava flows: Applications to the terrestrial planets

NASA Technical Reports Server (NTRS)

Zimbelman, James R.; Campbell, Bruce A.; Kousoum, Juliana; Lampkin, Derrick J.

1993-01-01

Lava flows are the visible expression of the extrusion of volcanic materials on a variety of planetary surfaces. A computer program described by Ishihara et al. appears to be well suited for application to different environments, and we have undertaken tests to evaluate their approach. Our results are somewhat mixed; the program does reproduce reasonable lava flow behavior in many situations, but we have encountered some conditions common to planetary environments for which the current program is inadequate. Here we present our initial efforts to identify the 'parameter space' for reasonable numerical simulations of lava flows.

Baseline performance of the GPU 3 Stirling engine

NASA Technical Reports Server (NTRS)

Thieme, L. G.; Tew, R. C., Jr.

1978-01-01

A 10 horsepower single-cylinder rhombic-drive Stirling engine was converted to a research configuration to obtain data for validation of Stirling computer simulations. The engine was originally built by General Motors Research Laboratories for the U.S. Army in 1965 as part of a 3 kW engine-generator set, designated the GHU 3 (Ground Power Unit). This report presents test results for a range of heater gas temperatures, mean compression-space pressures, and engine speeds with both helium and hydrogen as the working fluids. Also shown are initial data comparisons with computer simulation predictions.

Integrated autopilot/autothrottle for the NASA TSRV B-737 aircraft: Design and verification by nonlinear simulation

NASA Technical Reports Server (NTRS)

Bruce, Kevin R.

1989-01-01

An integrated autopilot/autothrottle was designed for flight test on the NASA TSRV B-737 aircraft. The system was designed using a total energy concept and is attended to achieve the following: (1) fuel efficiency by minimizing throttle activity; (2) low development and implementation costs by designing the control modes around a fixed inner loop design; and (3) maximum safety by preventing stall and engine overboost. The control law was designed initially using linear analysis; the system was developed using nonlinear simulations. All primary design requirements were satisfied.

Temperature distribution of a hot water storage tank in a simulated solar heating and cooling system

NASA Technical Reports Server (NTRS)

Namkoong, D.

1976-01-01

A 2,300-liter hot water storage tank was studied under conditions simulating a solar heating and cooling system. The initial condition of the tank, ranging from 37 C at the bottom to 94 C at the top, represented a condition midway through the start-up period of the system. During the five-day test period, the water in the tank gradually rose in temperature but in a manner that diminished its temperature stratification. Stratification was found not to be an important factor in the operation of the particular solar system studied.

Attenuation-emission alignment in cardiac PET∕CT based on consistency conditions

PubMed Central

Alessio, Adam M.; Kinahan, Paul E.; Champley, Kyle M.; Caldwell, James H.

2010-01-01

Purpose: In cardiac PET and PET∕CT imaging, misaligned transmission and emission images are a common problem due to respiratory and cardiac motion. This misalignment leads to erroneous attenuation correction and can cause errors in perfusion mapping and quantification. This study develops and tests a method for automated alignment of attenuation and emission data. Methods: The CT-based attenuation map is iteratively transformed until the attenuation corrected emission data minimize an objective function based on the Radon consistency conditions. The alignment process is derived from previous work by Welch et al. [“Attenuation correction in PET using consistency information,” IEEE Trans. Nucl. Sci. 45, 3134–3141 (1998)] for stand-alone PET imaging. The process was evaluated with the simulated data and measured patient data from multiple cardiac ammonia PET∕CT exams. The alignment procedure was applied to simulations of five different noise levels with three different initial attenuation maps. For the measured patient data, the alignment procedure was applied to eight attenuation-emission combinations with initially acceptable alignment and eight combinations with unacceptable alignment. The initially acceptable alignment studies were forced out of alignment a known amount and quantitatively evaluated for alignment and perfusion accuracy. The initially unacceptable studies were compared to the proposed aligned images in a blinded side-by-side review. Results: The proposed automatic alignment procedure reduced errors in the simulated data and iteratively approaches global minimum solutions with the patient data. In simulations, the alignment procedure reduced the root mean square error to less than 5 mm and reduces the axial translation error to less than 1 mm. In patient studies, the procedure reduced the translation error by >50% and resolved perfusion artifacts after a known misalignment for the eight initially acceptable patient combinations. The side-by-side review of the proposed aligned attenuation-emission maps and initially misaligned attenuation-emission maps revealed that reviewers preferred the proposed aligned maps in all cases, except one inconclusive case. Conclusions: The proposed alignment procedure offers an automatic method to reduce attenuation correction artifacts in cardiac PET∕CT and provides a viable supplement to subjective manual realignment tools. PMID:20384256

Internal Flow Simulation of Enhanced Performance Solid Rocket Booster for the Space Transportation System

NASA Technical Reports Server (NTRS)

Ahmad, Rashid A.; McCool, Alex (Technical Monitor)

2001-01-01

An enhanced performance solid rocket booster concept for the space shuttle system has been proposed. The concept booster will have strong commonality with the existing, proven, reliable four-segment Space Shuttle Reusable Solid Rocket Motors (RSRM) with individual component design (nozzle, insulator, etc.) optimized for a five-segment configuration. Increased performance is desirable to further enhance safety/reliability and/or increase payload capability. Performance increase will be achieved by adding a fifth propellant segment to the current four-segment booster and opening the throat to accommodate the increased mass flow while maintaining current pressure levels. One development concept under consideration is the static test of a "standard" RSRM with a fifth propellant segment inserted and appropriate minimum motor modifications. Feasibility studies are being conducted to assess the potential for any significant departure in component performance/loading from the well-characterized RSRM. An area of concern is the aft motor (submerged nozzle inlet, aft dome, etc.) where the altered internal flow resulting from the performance enhancing features (25% increase in mass flow rate, higher Mach numbers, modified subsonic nozzle contour) may result in increased component erosion and char. To assess this issue and to define the minimum design changes required to successfully static test a fifth segment RSRM engineering test motor, internal flow studies have been initiated. Internal aero-thermal environments were quantified in terms of conventional convective heating and discrete phase alumina particle impact/concentration and accretion calculations via Computational Fluid Dynamics (CFD) simulation. Two sets of comparative CFD simulations of the RSRM and the five-segment (IBM) concept motor were conducted with CFD commercial code FLUENT. The first simulation involved a two-dimensional axi-symmetric model of the full motor, initial grain RSRM. The second set of analyses included three-dimensional models of the RSRM and FSM aft motors with four-degree vectored nozzles.

Ares I-X First Stage Separation Loads and Dynamics Reconstruction

NASA Technical Reports Server (NTRS)

Demory, Lee; Rooker, BIll; Jarmulowicz, Marc; Glaese, John

2011-01-01

The Ares I-X flight test provided NASA with the opportunity to test hardware and gather critical data to ensure the success of future Ares I flights. One of the primary test flight objectives was to evaluate the environment during First Stage separation to better understand the conditions that the J-2X second stage engine will experience at ignition [1]. A secondary objective was to evaluate the effectiveness of the stage separation motors. The Ares I-X flight test vehicle was successfully launched on October 29, 2009, achieving most of its primary and secondary test objectives. Ground based video camera recordings of the separation event appeared to show recontact of the First Stage and the Upper Stage Simulator followed by an unconventional tumbling of the Upper Stage Simulator. Closer inspection of the videos and flight test data showed that recontact did not occur. Also, the motion during staging was as predicted through CFD analysis performed during the Ares I-X development. This paper describes the efforts to reconstruct the vehicle dynamics and loads through the staging event by means of a time integrated simulation developed in TREETOPS, a multi-body dynamics software tool developed at NASA [2]. The simulation was built around vehicle mass and geometry properties at the time of staging and thrust profiles for the first stage solid rocket motor as well as for the booster deceleration motors and booster tumble motors. Aerodynamic forces were determined by models created from a combination of wind tunnel testing and CFD. The initial conditions such as position, velocity, and attitude were obtained from the Best Estimated Trajectory (BET), which is compiled from multiple ground based and vehicle mounted instruments. Dynamic loads were calculated by subtracting the inertial forces from the applied forces. The simulation results were compared to the Best Estimated Trajectory, accelerometer flight data, and to ground based video.

Inhibition of chaotic escape from a potential well by incommensurate escape-suppressing excitations.

PubMed

Chacón, R; Martínez, J A

2002-03-01

Theoretical results are presented concerning the reduction of chaotic escape from a potential well by means of a harmonic parametric excitation that satisfies an ultrasubharmonic resonance condition with the escape-inducing excitation. The possibility of incommensurate escape-suppressing excitations is demonstrated by studying rational approximations to the irrational escape-suppressing frequency. The analytical predictions for the suitable amplitudes and initial phases of the escape-suppressing excitation are tested against numerical simulations based on a high-resolution grid of initial conditions. These numerical results indicate that the reduction of escape is reliably achieved for small amplitudes and at, and only at, the predicted initial phases. For the case of irrational escape-suppressing frequencies, the effective escape-reducing initial phases are found to lie close to the accumulation points of the set of suitable initial phases that are associated with the complete series of convergents up to the convergent giving the chosen rational approximation.

International Space Station Cathode Life Testing

NASA Technical Reports Server (NTRS)

Soulas, George C.; Sarver-Verhey, Timothy R.

1997-01-01

Four hollow cathode assembly (HCA) life tests were initiated at operating conditions simulating on-orbit operation of the International Space Station plasma contactor. The objective of these tests is to demonstrate the mission-required 18,000 hour lifetime with high-fidelity development model HCAS. HCAs are operated with a continuous 6 sccm xenon flow rate and 3 A anode current. On-orbit emission current requirements are simulated with a square waveform consisting of 50 minutes at a 2.5 A emission current and 40 minutes with no emission current. One HCA test was terminated after approximately 8,000 hours so that a destructive analysis could be performed. The analysis revealed no life-limiting processes and the ultimate lifetime was projected to be greater than the mission requirement. Testing continues for the remaining three HCAs which have accumulated approximately 8,000 hours, 10,000 hours, and 11,000 hours, respectively, as of June 1997. Anode and bias voltages, strong indicators of cathode electron emitter condition, are within acceptable ranges and have exhibited no life- or performance-limiting phenomena to date.

Initial Effects of NO x on Idodine and Methyl Iodine Loading of AgZ and Aerogels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruffey, Stephanie H.; Jubin, Robert Thomas

2015-03-31

This initial evaluation provides insight into the effect of NO on the adsorption of both I 2 and CH 3I onto reduced silver-exchanged mordenite (Ag 0Z). It was determined that adsorption of CH 3I onto Ag 0Z occurs at approximately 50% of the rate of I 2 adsorption onto Ag 0Z, although total iodine capacities are comparable. Addition of 1% NO to the simulated off-gas stream results in very similar loading behaviors and iodine capacities for both iodine species. This is most likely an effect of CH 3I oxidation to I 2 by NO prior to contact with the sorbentmore » bed. Completion of tests including NO 2 in the simulated off-gas stream was delayed due to vendor NO 2 production schedules. A statistically designed test matrix is partially completed, and upon conclusion of the suggested experiments, the effects of temperature, NO, NO 2, and water vapor on the sorption of CH 3I and I 2 onto Ag 0Z will be able to be statistically resolved. This work represents progress towards that aim.« less

Numerical Investigation of Fracture Propagation in Geomaterials

NASA Astrophysics Data System (ADS)

Newell, P.; Borowski, E.; Major, J. R.; Eichhubl, P.

2015-12-01

Fracture in geomaterials is a critical behavior that affects the long-term structural response of geosystems. The processes involving fracture initiation and growth in rocks often span broad time scales and size scales, contributing to the complexity of these problems. To better understand fracture behavior, the authors propose an initial investigation comparing the fracture testing techniques of notched three-point bending (N3PB), short rod (SR), and double torsion (DT) on geomaterials using computational analysis. Linear softening cohesive fracture modeling (LCFM) was applied using ABAQUS to computationally simulate the three experimental set-ups. By applying material properties obtained experimentally, these simulations are intended to predict single-trace fracture growth. The advantages and limitations of the three testing techniques were considered for application to subcritical fracture propagation taking into account the accuracy of constraints, load applications, and modes of fracture. This work is supported as part of the Geomechanics of CO2 Reservoir Seals, a DOE-NETL funded under Award Number DE-FOA-0001037. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Bivalves: From individual to population modelling

NASA Astrophysics Data System (ADS)

Saraiva, S.; van der Meer, J.; Kooijman, S. A. L. M.; Ruardij, P.

2014-11-01

An individual based population model for bivalves was designed, built and tested in a 0D approach, to simulate the population dynamics of a mussel bed located in an intertidal area. The processes at the individual level were simulated following the dynamic energy budget theory, whereas initial egg mortality, background mortality, food competition, and predation (including cannibalism) were additional population processes. Model properties were studied through the analysis of theoretical scenarios and by simulation of different mortality parameter combinations in a realistic setup, imposing environmental measurements. Realistic criteria were applied to narrow down the possible combination of parameter values. Field observations obtained in the long-term and multi-station monitoring program were compared with the model scenarios. The realistically selected modeling scenarios were able to reproduce reasonably the timing of some peaks in the individual abundances in the mussel bed and its size distribution but the number of individuals was not well predicted. The results suggest that the mortality in the early life stages (egg and larvae) plays an important role in population dynamics, either by initial egg mortality, larvae dispersion, settlement failure or shrimp predation. Future steps include the coupling of the population model with a hydrodynamic and biogeochemical model to improve the simulation of egg/larvae dispersion, settlement probability, food transport and also to simulate the feedback of the organisms' activity on the water column properties, which will result in an improvement of the food quantity and quality characterization.

Induction hardening treatment and simulation for a grey cast iron used in engine cylinder liners

NASA Astrophysics Data System (ADS)

Castellanos-Leal, E. L.; Miranda, D. A.; Coy, A. E.; Barrero, J. G.; González, J. A.; Vesga Rueda, O. P.

2017-01-01

In this research, a technical study of induction hardening in a grey cast iron used in engine cylinder liners manufactured by LAVCO Ltda., a Colombian foundry company, was carried out. Metallurgical parameters such as austenitization temperature, cooling rate, and quenching severity were determined. These factors are exclusively dependent on chemical composition and initial microstructure of grey cast iron. Simulations of induction heating through finite elements method were performed and, the most appropriate experimental conditions to achieve the critical transformation temperature was evaluated to reach a proper surface hardening on the piece. Preliminary results revealed an excellent approximation between simulation and heating test performed with a full bridge inverter voltage adapted with local technology.

Trends and Techniques for Space Base Electronics

NASA Technical Reports Server (NTRS)

Trotter, J. D.; Wade, T. E.; Gassaway, J. D.

1979-01-01

Simulations of various phosphorus and boron diffusions in SOS were completed and a sputtering system, furnaces, and photolithography related equipment were set up. Double layer metal experiments initially utilized wet chemistry techniques. By incorporating ultrasonic etching of the vias, premetal cleaning a modified buffered HF, phosphorus doped vapox, and extended sintering, yields of 98% were obtained using the standard test pattern. A two dimensional modeling program was written for simulating short channel MOSFETs with nonuniform substrate doping. A key simplifying assumption used is that the majority carriers can be represented by a sheet charge at the silicon dioxide silicon interface. Although the program is incomplete, the two dimensional Poisson equation for the potential distribution was achieved. The status of other Z-D MOSFET simulation programs is summarized.

GENASIS: General Astrophysical Simulation System. I. Refinable Mesh and Nonrelativistic Hydrodynamics

NASA Astrophysics Data System (ADS)

Cardall, Christian Y.; Budiardja, Reuben D.; Endeve, Eirik; Mezzacappa, Anthony

2014-02-01

GenASiS (General Astrophysical Simulation System) is a new code being developed initially and primarily, though by no means exclusively, for the simulation of core-collapse supernovae on the world's leading capability supercomputers. This paper—the first in a series—demonstrates a centrally refined coordinate patch suitable for gravitational collapse and documents methods for compressible nonrelativistic hydrodynamics. We benchmark the hydrodynamics capabilities of GenASiS against many standard test problems; the results illustrate the basic competence of our implementation, demonstrate the strengths and limitations of the HLLC relative to the HLL Riemann solver in a number of interesting cases, and provide preliminary indications of the code's ability to scale and to function with cell-by-cell fixed-mesh refinement.

Predicting debris-flow initiation and run-out with a depth-averaged two-phase model and adaptive numerical methods

NASA Astrophysics Data System (ADS)

George, D. L.; Iverson, R. M.

2012-12-01

Numerically simulating debris-flow motion presents many challenges due to the complicated physics of flowing granular-fluid mixtures, the diversity of spatial scales (ranging from a characteristic particle size to the extent of the debris flow deposit), and the unpredictability of the flow domain prior to a simulation. Accurately predicting debris-flows requires models that are complex enough to represent the dominant effects of granular-fluid interaction, while remaining mathematically and computationally tractable. We have developed a two-phase depth-averaged mathematical model for debris-flow initiation and subsequent motion. Additionally, we have developed software that numerically solves the model equations efficiently on large domains. A unique feature of the mathematical model is that it includes the feedback between pore-fluid pressure and the evolution of the solid grain volume fraction, a process that regulates flow resistance. This feature endows the model with the ability to represent the transition from a stationary mass to a dynamic flow. With traditional approaches, slope stability analysis and flow simulation are treated separately, and the latter models are often initialized with force balances that are unrealistically far from equilibrium. Additionally, our new model relies on relatively few dimensionless parameters that are functions of well-known material properties constrained by physical data (eg. hydraulic permeability, pore-fluid viscosity, debris compressibility, Coulomb friction coefficient, etc.). We have developed numerical methods and software for accurately solving the model equations. By employing adaptive mesh refinement (AMR), the software can efficiently resolve an evolving debris flow as it advances through irregular topography, without needing terrain-fit computational meshes. The AMR algorithms utilize multiple levels of grid resolutions, so that computationally inexpensive coarse grids can be used where the flow is absent, and much higher resolution grids evolve with the flow. The reduction in computational cost, due to AMR, makes very large-scale problems tractable on personal computers. Model accuracy can be tested by comparison of numerical predictions and empirical data. These comparisons utilize controlled experiments conducted at the USGS debris-flow flume, which provide detailed data about flow mobilization and dynamics. Additionally, we have simulated historical large-scale debris flows, such as the (≈50 million m^3) debris flow that originated on Mt. Meager, British Columbia in 2010. This flow took a very complex route through highly variable topography and provides a valuable benchmark for testing. Maps of the debris flow deposit and data from seismic stations provide evidence regarding flow initiation, transit times and deposition. Our simulations reproduce many of the complex patterns of the event, such as run-out geometry and extent, and the large-scale nature of the flow and the complex topographical features demonstrate the utility of AMR in flow simulations.

Mesoscale acid deposition modeling studies

NASA Technical Reports Server (NTRS)

Kaplan, Michael L.; Proctor, F. H.; Zack, John W.; Karyampudi, V. Mohan; Price, P. E.; Bousquet, M. D.; Coats, G. D.

1989-01-01

The work performed in support of the EPA/DOE MADS (Mesoscale Acid Deposition) Project included the development of meteorological data bases for the initialization of chemistry models, the testing and implementation of new planetary boundary layer parameterization schemes in the MASS model, the simulation of transport and precipitation for MADS case studies employing the MASS model, and the use of the TASS model in the simulation of cloud statistics and the complex transport of conservative tracers within simulated cumuloform clouds. The work performed in support of the NASA/FAA Wind Shear Program included the use of the TASS model in the simulation of the dynamical processes within convective cloud systems, the analyses of the sensitivity of microburst intensity and general characteristics as a function of the atmospheric environment within which they are formed, comparisons of TASS model microburst simulation results to observed data sets, and the generation of simulated wind shear data bases for use by the aviation meteorological community in the evaluation of flight hazards caused by microbursts.

Modelling the graphite fracture mechanisms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacquemoud, C.; Marie, S.; Nedelec, M.

2012-07-01

In order to define a design criterion for graphite components, it is important to identify the physical phenomena responsible for the graphite fracture, to include them in a more effective modelling. In a first step, a large panel of experiments have been realised in order to build up an important database; results of tensile tests, 3 and 4 point bending tests on smooth and notched specimens have been analysed and have demonstrated an important geometry related effects on the behavior up to fracture. Then, first simulations with an elastic or an elastoplastic bilinear constitutive law have not made it possiblemore » to simulate the experimental fracture stress variations with the specimen geometry, the fracture mechanisms of the graphite being at the microstructural scale. That is the reason why a specific F.E. model of the graphite structure has been developed in which every graphite grain has been meshed independently, the crack initiation along the basal plane of the particles as well as the crack propagation and coalescence have been modelled too. This specific model has been used to test two different approaches for fracture initiation: a critical stress criterion and two criteria of fracture mechanic type. They are all based on crystallographic considerations as a global critical stress criterion gave unsatisfactory results. The criteria of fracture mechanic type being extremely unstable and unable to represent the graphite global behaviour up to the final collapse, the critical stress criterion has been preferred to predict the results of the large range of available experiments, on both smooth and notched specimens. In so doing, the experimental observations have been correctly simulated: the geometry related effects on the experimental fracture stress dispersion, the specimen volume effects on the macroscopic fracture stress and the crack propagation at a constant stress intensity factor. In addition, the parameters of the criterion have been related to experimental observations: the local crack initiation stress of 8 MPa corresponds to the non-linearity apparition on the global behavior observed experimentally and the the maximal critical stress defined for the particle of 30 MPa is equivalent to the fracture stress of notched specimens. This innovative combination of crack modelling and a local crystallographic critical stress criterion made it possible to understand that cleavage initiation and propagation in the graphite microstructure was driven by a mean critical stress criterion. (authors)« less

Mars Tumbleweed Simulation Using Singular Perturbation Theory

NASA Technical Reports Server (NTRS)

Raiszadeh, Behzad; Calhoun, Phillip

2005-01-01

The Mars Tumbleweed is a new surface rover concept that utilizes Martian winds as the primary source of mobility. Several designs have been proposed for the Mars Tumbleweed, all using aerodynamic drag to generate force for traveling about the surface. The Mars Tumbleweed, in its deployed configuration, must be large and lightweight to provide the ratio of drag force to rolling resistance necessary to initiate motion from the Martian surface. This paper discusses the dynamic simulation details of a candidate Tumbleweed design. The dynamic simulation model must properly evaluate and characterize the motion of the tumbleweed rover to support proper selection of system design parameters. Several factors, such as model flexibility, simulation run times, and model accuracy needed to be considered in modeling assumptions. The simulation was required to address the flexibility of the rover and its interaction with the ground, and properly evaluate its mobility. Proper assumptions needed to be made such that the simulated dynamic motion is accurate and realistic while not overly burdened by long simulation run times. This paper also shows results that provided reasonable correlation between the simulation and a drop/roll test of a tumbleweed prototype.

Comparison of Analytical Predictions and Experimental Results for a Dual Brayton Power System (Discussion on Test Hardware and Computer Model for a Dual Brayton System)

NASA Technical Reports Server (NTRS)

Johnson, Paul K.

2007-01-01

NASA Glenn Research Center (GRC) contracted Barber-Nichols, Arvada, CO to construct a dual Brayton power conversion system for use as a hardware proof of concept and to validate results from a computational code known as the Closed Cycle System Simulation (CCSS). Initial checkout tests were performed at Barber- Nichols to ready the system for delivery to GRC. This presentation describes the system hardware components and lists the types of checkout tests performed along with a couple issues encountered while conducting the tests. A description of the CCSS model is also presented. The checkout tests did not focus on generating data, therefore, no test data or model analyses are presented.

Evaluating average and atypical response in radiation effects simulations

NASA Astrophysics Data System (ADS)

Weller, R. A.; Sternberg, A. L.; Massengill, L. W.; Schrimpf, R. D.; Fleetwood, D. M.

2003-12-01

We examine the limits of performing single-event simulations using pre-averaged radiation events. Geant4 simulations show the necessity, for future devices, to supplement current methods with ensemble averaging of device-level responses to physically realistic radiation events. Initial Monte Carlo simulations have generated a significant number of extremal events in local energy deposition. These simulations strongly suggest that proton strikes of sufficient energy, even those that initiate purely electronic interactions, can initiate device response capable in principle of producing single event upset or microdose damage in highly scaled devices.

Development of the GPM Observatory Thermal Vacuum Test Model

NASA Technical Reports Server (NTRS)

Yang, Kan; Peabody, Hume

2012-01-01

A software-based thermal modeling process was documented for generating the thermal panel settings necessary to simulate worst-case on-orbit flight environments in an observatory-level thermal vacuum test setup. The method for creating such a thermal model involved four major steps: (1) determining the major thermal zones for test as indicated by the major dissipating components on the spacecraft, then mapping the major heat flows between these components; (2) finding the flight equivalent sink temperatures for these test thermal zones; (3) determining the thermal test ground support equipment (GSE) design and initial thermal panel settings based on the equivalent sink temperatures; and (4) adjusting the panel settings in the test model to match heat flows and temperatures with the flight model. The observatory test thermal model developed from this process allows quick predictions of the performance of the thermal vacuum test design. In this work, the method described above was applied to the Global Precipitation Measurement (GPM) core observatory spacecraft, a joint project between NASA and the Japanese Aerospace Exploration Agency (JAXA) which is currently being integrated at NASA Goddard Space Flight Center for launch in Early 2014. From preliminary results, the thermal test model generated from this process shows that the heat flows and temperatures match fairly well with the flight thermal model, indicating that the test model can simulate fairly accurately the conditions on-orbit. However, further analysis is needed to determine the best test configuration possible to validate the GPM thermal design before the start of environmental testing later this year. Also, while this analysis method has been applied solely to GPM, it should be emphasized that the same process can be applied to any mission to develop an effective test setup and panel settings which accurately simulate on-orbit thermal environments.

Global Response to Local Ionospheric Mass Ejection

NASA Technical Reports Server (NTRS)

Moore, T. E.; Fok, M.-C.; Delcourt, D. C.; Slinker, S. P.; Fedder, J. A.

2010-01-01

We revisit a reported "Ionospheric Mass Ejection" using prior event observations to guide a global simulation of local ionospheric outflows, global magnetospheric circulation, and plasma sheet pressurization, and comparing our results with the observed global response. Our simulation framework is based on test particle motions in the Lyon-Fedder-Mobarry (LFM) global circulation model electromagnetic fields. The inner magnetosphere is simulated with the Comprehensive Ring Current Model (CRCM) of Fok and Wolf, driven by the transpolar potential developed by the LFM magnetosphere, and includes an embedded plasmaspheric simulation. Global circulation is stimulated using the observed solar wind conditions for the period 24-25 Sept 1998. This period begins with the arrival of a Coronal Mass Ejection, initially with northward, but later with southward interplanetary magnetic field. Test particles are launched from the ionosphere with fluxes specified by local empirical relationships of outflow to electrodynamic and particle precipitation imposed by the MIlD simulation. Particles are tracked until they are lost from the system downstream or into the atmosphere, using the full equations of motion. Results are compared with the observed ring current and a simulation of polar and auroral wind outflows driven globally by solar wind dynamic pressure. We find good quantitative agreement with the observed ring current, and reasonable qualitative agreement with earlier simulation results, suggesting that the solar wind driven global simulation generates realistic energy dissipation in the ionosphere and that the Strangeway relations provide a realistic local outflow description.

METC CFD simulations of hot gas filtration

DOE Office of Scientific and Technical Information (OSTI.GOV)

O`Brien, T.J.

1995-06-01

Computational Fluid Dynamic (CFD) simulations of the fluid/particle flow in several hot gas filtration vessels will be presented. These simulations have been useful in designing filtration vessels and in diagnosing problems with filter operation. The simulations were performed using the commercial code FLUENT and the METC-developed code MFIX. Simulations of the initial configuration of the Karhula facility indicated that the dirty gas flow over the filter assemblage was very non-uniform. The force of the dirty gas inlet flow was inducing a large circulation pattern that caused flow around the candles to be in opposite directions on opposite sides of themore » vessel. By introducing a system of baffles, a more uniform flow pattern was developed. This modification may have contributed to the success of the project. Several simulations of configurations proposed by Industrial Filter and Pump were performed, varying the position of the inlet. A detailed resolution of the geometry of the candles allowed determination of the flow between the individual candles. Recent simulations in support of the METC/CeraMem Cooperative Research and Development Agreement have analyzed the flow in the vessel during the cleaning back-pulse. Visualization of experiments at the CeraMem cold-flow facility provided confidence in the use of CFD. Extensive simulations were then performed to assist in the design of the hot test facility being built by Ahlstrom/Pyropower. These tests are intended to demonstrate the CeraMem technology.« less

Mechanical characteristics and comparisons of cerclage wires: introduction of the double-wrap and loop/twist tying methods.

PubMed

Roe, S C

1997-01-01

Evaluate the mechanical properties of twist, loop, double loop, double-wrap and loop/twist cerclage. The initial tension generated by 18 cerclage of each type was determined using a materials testing machine after tying around a testing jig. Six wires from each type were distracted and the initial stiffness and yield load were determined. Yield behavior was further investigated in six wires of each type by determining the load required to reduce cerclage tension below 30 Newton (N) following and incremental (50 N) stepwise load and unload regimen. The amount of collapse of the simulated bone fragments that resulted in the reduction of initial tension to 30 N was measured for the final six wires of each group. Data were analyzed by analysis of variance and a multiple comparison test. Twist type cerclage generated less tension than loop-type cerclage. The yield load of these two types was similar. Double-loop and double-wrap cerclage generated superior tension and resisted a greater load before loosening. Loop/twist cerclage had an intermediate initial tension but had the greatest resistance to loading. In the collapse test, the greater the initial tension, the more collapse could occur before the wire was loose. For all types of cerclage wire fixation, a reduction of diameter of the testing jig of more than 1% caused loosening. Double-loop and double-wrap cerclage provide greater compression of fragments and resist loads associated with weight-bearing better than the twist and loop methods. Loop/twist cerclage may have advantages because of their superior resistance to loading. All cerclage will loosen if fracture fragments collapse.

(Re)evaluating the Implications of the Autoregressive Latent Trajectory Model Through Likelihood Ratio Tests of Its Initial Conditions.

PubMed

Ou, Lu; Chow, Sy-Miin; Ji, Linying; Molenaar, Peter C M

2017-01-01

The autoregressive latent trajectory (ALT) model synthesizes the autoregressive model and the latent growth curve model. The ALT model is flexible enough to produce a variety of discrepant model-implied change trajectories. While some researchers consider this a virtue, others have cautioned that this may confound interpretations of the model's parameters. In this article, we show that some-but not all-of these interpretational difficulties may be clarified mathematically and tested explicitly via likelihood ratio tests (LRTs) imposed on the initial conditions of the model. We show analytically the nested relations among three variants of the ALT model and the constraints needed to establish equivalences. A Monte Carlo simulation study indicated that LRTs, particularly when used in combination with information criterion measures, can allow researchers to test targeted hypotheses about the functional forms of the change process under study. We further demonstrate when and how such tests may justifiably be used to facilitate our understanding of the underlying process of change using a subsample (N = 3,995) of longitudinal family income data from the National Longitudinal Survey of Youth.

Electron and ion heating by whistler turbulence: Three-dimensional particle-in-cell simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hughes, R. Scott; Gary, S. Peter; Wang, Joseph

2014-12-17

Three-dimensional particle-in-cell simulations of decaying whistler turbulence are carried out on a collisionless, homogeneous, magnetized, electron-ion plasma model. In addition, the simulations use an initial ensemble of relatively long wavelength whistler modes with a broad range of initial propagation directions with an initial electron beta β e = 0.05. The computations follow the temporal evolution of the fluctuations as they cascade into broadband turbulent spectra at shorter wavelengths. Three simulations correspond to successively larger simulation boxes and successively longer wavelengths of the initial fluctuations. The computations confirm previous results showing electron heating is preferentially parallel to the background magnetic fieldmore » B o, and ion heating is preferentially perpendicular to B o. The new results here are that larger simulation boxes and longer initial whistler wavelengths yield weaker overall dissipation, consistent with linear dispersion theory predictions of decreased damping, stronger ion heating, consistent with a stronger ion Landau resonance, and weaker electron heating.« less

A new and inexpensive non-bit-for-bit solution reproducibility test based on time step convergence (TSC1.0)

DOE PAGES

Wan, Hui; Zhang, Kai; Rasch, Philip J.; ...

2017-02-03

A test procedure is proposed for identifying numerically significant solution changes in evolution equations used in atmospheric models. The test issues a fail signal when any code modifications or computing environment changes lead to solution differences that exceed the known time step sensitivity of the reference model. Initial evidence is provided using the Community Atmosphere Model (CAM) version 5.3 that the proposed procedure can be used to distinguish rounding-level solution changes from impacts of compiler optimization or parameter perturbation, which are known to cause substantial differences in the simulated climate. The test is not exhaustive since it does not detect issues associatedmore » with diagnostic calculations that do not feedback to the model state variables. Nevertheless, it provides a practical and objective way to assess the significance of solution changes. The short simulation length implies low computational cost. The independence between ensemble members allows for parallel execution of all simulations, thus facilitating fast turnaround. The new method is simple to implement since it does not require any code modifications. We expect that the same methodology can be used for any geophysical model to which the concept of time step  convergence is applicable.« less

Advanced Stirling Convertor Testing at NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Oriti, Salvatore M.; Blaze, Gina M.

2007-01-01

The U.S. Department of Energy (DOE), Lockheed Martin Space Systems (LMSS), Sunpower Inc., and NASA Glenn Research Center (GRC) have been developing an Advanced Stirling Radioisotope Generator (ASRG) for use as a power system on space science and exploration missions. This generator will make use of the free-piston Stirling convertors to achieve higher conversion efficiency than currently available alternatives. The ASRG will utilize two Advanced Stirling Convertors (ASC) to convert thermal energy from a radioisotope heat source to electricity. NASA GRC has initiated several experiments to demonstrate the functionality of the ASC, including: in-air extended operation, thermal vacuum extended operation, and ASRG simulation for mobile applications. The in-air and thermal vacuum test articles are intended to provide convertor performance data over an extended operating time. These test articles mimic some features of the ASRG without the requirement of low system mass. Operation in thermal vacuum adds the element of simulating deep space. This test article is being used to gather convertor performance and thermal data in a relevant environment. The ASRG simulator was designed to incorporate a minimum amount of support equipment, allowing integration onto devices powered directly by the convertors, such as a rover. This paper discusses the design, fabrication, and implementation of these experiments.

Development of a Computer-Adaptive Physical Function Instrument for Social Security Administration Disability Determination

PubMed Central

Ni, Pengsheng; McDonough, Christine M.; Jette, Alan M.; Bogusz, Kara; Marfeo, Elizabeth E.; Rasch, Elizabeth K.; Brandt, Diane E.; Meterko, Mark; Chan, Leighton

2014-01-01

Objectives To develop and test an instrument to assess physical function (PF) for Social Security Administration (SSA) disability programs, the SSA-PF. Item Response Theory (IRT) analyses were used to 1) create a calibrated item bank for each of the factors identified in prior factor analyses, 2) assess the fit of the items within each scale, 3) develop separate Computer-Adaptive Test (CAT) instruments for each scale, and 4) conduct initial psychometric testing. Design Cross-sectional data collection; IRT analyses; CAT simulation. Setting Telephone and internet survey. Participants Two samples: 1,017 SSA claimants, and 999 adults from the US general population. Interventions None. Main Outcome Measure Model fit statistics, correlation and reliability coefficients, Results IRT analyses resulted in five unidimensional SSA-PF scales: Changing & Maintaining Body Position, Whole Body Mobility, Upper Body Function, Upper Extremity Fine Motor, and Wheelchair Mobility for a total of 102 items. High CAT accuracy was demonstrated by strong correlations between simulated CAT scores and those from the full item banks. Comparing the simulated CATs to the full item banks, very little loss of reliability or precision was noted, except at the lower and upper ranges of each scale. No difference in response patterns by age or sex was noted. The distributions of claimant scores were shifted to the lower end of each scale compared to those of a sample of US adults. Conclusions The SSA-PF instrument contributes important new methodology for measuring the physical function of adults applying to the SSA disability programs. Initial evaluation revealed that the SSA-PF instrument achieved considerable breadth of coverage in each content domain and demonstrated noteworthy psychometric properties. PMID:23578594

Environmental Barrier Coating Fracture, Fatigue and High-Heat-Flux Durability Modeling and Stochastic Progressive Damage Simulation

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Nemeth, Noel N.

2017-01-01

Advanced environmental barrier coatings will play an increasingly important role in future gas turbine engines because of their ability to protect emerging light-weight SiC/SiC ceramic matrix composite (CMC) engine components, further raising engine operating temperatures and performance. Because the environmental barrier coating systems are critical to the performance, reliability and durability of these hot-section ceramic engine components, a prime-reliant coating system along with established life design methodology are required for the hot-section ceramic component insertion into engine service. In this paper, we have first summarized some observations of high temperature, high-heat-flux environmental degradation and failure mechanisms of environmental barrier coating systems in laboratory simulated engine environment tests. In particular, the coating surface cracking morphologies and associated subsequent delamination mechanisms under the engine level high-heat-flux, combustion steam, and mechanical creep and fatigue loading conditions will be discussed. The EBC compostion and archtechture improvements based on advanced high heat flux environmental testing, and the modeling advances based on the integrated Finite Element Analysis Micromechanics Analysis Code/Ceramics Analysis and Reliability Evaluation of Structures (FEAMAC/CARES) program will also be highlighted. The stochastic progressive damage simulation successfully predicts mud flat damage pattern in EBCs on coated 3-D specimens, and a 2-D model of through-the-thickness cross-section. A 2-parameter Weibull distribution was assumed in characterizing the coating layer stochastic strength response and the formation of damage was therefore modeled. The damage initiation and coalescence into progressively smaller mudflat crack cells was demonstrated. A coating life prediction framework may be realized by examining the surface crack initiation and delamination propagation in conjunction with environmental degradation under high-heat-flux and environment load test conditions.

Development of a computer-adaptive physical function instrument for Social Security Administration disability determination.

PubMed

Ni, Pengsheng; McDonough, Christine M; Jette, Alan M; Bogusz, Kara; Marfeo, Elizabeth E; Rasch, Elizabeth K; Brandt, Diane E; Meterko, Mark; Haley, Stephen M; Chan, Leighton

2013-09-01

To develop and test an instrument to assess physical function for Social Security Administration (SSA) disability programs, the SSA-Physical Function (SSA-PF) instrument. Item response theory (IRT) analyses were used to (1) create a calibrated item bank for each of the factors identified in prior factor analyses, (2) assess the fit of the items within each scale, (3) develop separate computer-adaptive testing (CAT) instruments for each scale, and (4) conduct initial psychometric testing. Cross-sectional data collection; IRT analyses; CAT simulation. Telephone and Internet survey. Two samples: SSA claimants (n=1017) and adults from the U.S. general population (n=999). None. Model fit statistics, correlation, and reliability coefficients. IRT analyses resulted in 5 unidimensional SSA-PF scales: Changing & Maintaining Body Position, Whole Body Mobility, Upper Body Function, Upper Extremity Fine Motor, and Wheelchair Mobility for a total of 102 items. High CAT accuracy was demonstrated by strong correlations between simulated CAT scores and those from the full item banks. On comparing the simulated CATs with the full item banks, very little loss of reliability or precision was noted, except at the lower and upper ranges of each scale. No difference in response patterns by age or sex was noted. The distributions of claimant scores were shifted to the lower end of each scale compared with those of a sample of U.S. adults. The SSA-PF instrument contributes important new methodology for measuring the physical function of adults applying to the SSA disability programs. Initial evaluation revealed that the SSA-PF instrument achieved considerable breadth of coverage in each content domain and demonstrated noteworthy psychometric properties. Copyright © 2013 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Numerical Propulsion System Simulation (NPSS): An Award Winning Propulsion System Simulation Tool

NASA Technical Reports Server (NTRS)

Stauber, Laurel J.; Naiman, Cynthia G.

2002-01-01

The Numerical Propulsion System Simulation (NPSS) is a full propulsion system simulation tool used by aerospace engineers to predict and analyze the aerothermodynamic behavior of commercial jet aircraft, military applications, and space transportation. The NPSS framework was developed to support aerospace, but other applications are already leveraging the initial capabilities, such as aviation safety, ground-based power, and alternative energy conversion devices such as fuel cells. By using the framework and developing the necessary components, future applications that NPSS could support include nuclear power, water treatment, biomedicine, chemical processing, and marine propulsion. NPSS will dramatically reduce the time, effort, and expense necessary to design and test jet engines. It accomplishes that by generating sophisticated computer simulations of an aerospace object or system, thus enabling engineers to "test" various design options without having to conduct costly, time-consuming real-life tests. The ultimate goal of NPSS is to create a numerical "test cell" that enables engineers to create complete engine simulations overnight on cost-effective computing platforms. Using NPSS, engine designers will be able to analyze different parts of the engine simultaneously, perform different types of analysis simultaneously (e.g., aerodynamic and structural), and perform analysis in a more efficient and less costly manner. NPSS will cut the development time of a new engine in half, from 10 years to 5 years. And NPSS will have a similar effect on the cost of development: new jet engines will cost about a billion dollars to develop rather than two billion. NPSS is also being applied to the development of space transportation technologies, and it is expected that similar efficiencies and cost savings will result. Advancements of NPSS in fiscal year 2001 included enhancing the NPSS Developer's Kit to easily integrate external components of varying fidelities, providing the initial Visual-Based Syntax (VBS) capability, and developing additional capabilities to support space transportation. NPSS was supported under NASA's High Performance Computing and Communications Program. Through the NASA/Industry Cooperative Effort agreement, NASA Glenn and its industry and Government partners are developing NPSS. The NPSS team consists of propulsion experts and software engineers from GE Aircraft Engines, Pratt & Whitney, The Boeing Company, Honeywell, Rolls-Royce Corporation, Williams International, Teledyne Continental Motors, Arnold Engineering Development Center, Wright Patterson Air Force Base, and the NASA Glenn Research Center. Glenn is leading the way in developing NPSS--a method for solving complex design problems that's faster, better, and cheaper.

Impact of Gluma Desensitizer on the tensile strength of zirconia crowns bonded to dentin: an in vitro study.

PubMed

Stawarczyk, Bogna; Hartmann, Leonie; Hartmann, Rahel; Roos, Malgorzata; Ender, Andreas; Ozcan, Mutlu; Sailer, Irena; Hämmerle, Christoph H F

2012-02-01

This study tested the impact of Gluma Desensitizer on the tensile strength of zirconia crowns bonded to dentin. Human teeth were prepared and randomly divided into six groups (N = 144, n = 24 per group). For each tooth, a zirconia crown was manufactured. The zirconia crowns were cemented with: (1) Panavia21 (PAN), (2) Panavia21 combined with Gluma Desensitizer (PAN-G), (3) RelyX Unicem (RXU), (4) RelyX Unicem combined with Gluma Desensitizer (RXU-G), (5) G-Cem (GCM) and (6) G-Cem combined with Gluma Desensitizer (GCM-G). The initial tensile strength was measured in half (n = 12) of each group and the other half (n = 12) subjected to a chewing machine (1.2 Mio, 49 N, 5°C/50°C). The cemented crowns were pulled in a Universal Testing Machine (1 mm/min, Zwick Z010) until failure occurred and tensile strength was calculated. Data were analyzed with one-way and two-way ANOVA followed by a post hoc Scheffé test, t test and Kaplan-Meier analysis with a Breslow-Gehan analysis test (α = 0.05). After the chewing simulation, the self-adhesive resin cements combined with Gluma Desensitizer showed significantly higher tensile strength (RXU-G, 12.8 ± 4.3 MPa; GCM-G, 13.4 ± 6.2 MPa) than PAN (7.3 ± 1.7 MPa) and PAN-G (0.9 ± 0.6). Within the groups, PAN, PAN-G and RXU resulted in significantly lower values when compared to the initial tensile strength; the values of all other test groups were stable. In this study, self-adhesive resin cements combined with Gluma Desensitizer reached better long-term stability compared to PAN and PAN-G after chewing simulation.

Heavy-section steel irradiation program. Progress report, April 1996--September 1996

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corwin, W.R.

1997-09-01

The Heavy-Section Steel Irradiation Program was established to quantitatively assess the effects of neutron irradiation on the material behavior of typical reactor pressure vessel (RPV) steels. During this period, fracture mechanics testing of specimens of the irradiated low upper shelf (LUS) weld were completed and analyses performed. Heat treatment of five RPV plate materials was initiated to examine phosphorus segregation effects on the fracture toughness of the heat affected zone of welds. Initial results show that all five materials exhibited very large prior austenite grain sizes as a consequence of the initial heat treatment. Irradiated and annealed specimens of LUSmore » weld material were tested and analyzed. Four sets of Charpy V-notch (CVN) specimens were aged at various temperatures and tested to examine the reason for overrecovery of upper shelf energy that has been observed. Molecular dynamics cascade simulations were extended to 40 keV and have provided information representative of most of the fast neutron spectrum. Investigations of the correlation between microstructural changes and hardness changes in irradiated model alloys was also completed. Preliminary planning for test specimen machining for the Japan Power Development Reactor was completed. A database of Charpy impact and fracture toughness data for RPV materials that have been tested in the unirradiated and irradiated conditions is being assembled and analyzed. Weld metal appears to have similar CVN and fracture toughness transition temperature shifts, whereas the fracture toughness shifts are greater than CVN shifts for base metals. Draft subcontractor reports on precracked cylindrical tensile specimens were completed, reviewed, and are being revised. Testing on precracked CVN specimens, both quasi-static and dynamic, was evaluated. Additionally, testing of compact specimens was initiated as an experimental comparison of constraint limitations. 16 figs., 2 tabs.« less

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

PubMed

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 Nursing © 2010 Blackwell Publishing Ltd.

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

PubMed Central

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 in the clinical setting. PMID:20636471

Arthroscopic Shoulder Surgical Simulation Training Curriculum: Transfer Reliability and Maintenance of Skill Over Time.

PubMed

Dunn, John C; Belmont, Philip J; Lanzi, Joseph; Martin, Kevin; Bader, Julia; Owens, Brett; Waterman, Brian R

2015-01-01

Surgical education is evolving as work hour constraints limit the exposure of residents to the operating room. Potential consequences may include erosion of resident education and decreased quality of patient care. Surgical simulation training has become a focus of study in an effort to counter these challenges. Previous studies have validated the use of arthroscopic surgical simulation programs both in vitro and in vivo. However, no study has examined if the gains made by residents after a simulation program are retained after a period away from training. In all, 17 orthopedic surgery residents were randomized into simulation or standard practice groups. All subjects were oriented to the arthroscopic simulator, a 14-point anatomic checklist, and Arthroscopic Surgery Skill Evaluation Tool (ASSET). The experimental group received 1 hour of simulation training whereas the control group had no additional training. All subjects performed a recorded, diagnostic arthroscopy intraoperatively. These videos were scored by 2 blinded, fellowship-trained orthopedic surgeons and outcome measures were compared within and between the groups. After 1 year in which neither group had exposure to surgical simulation training, all residents were retested intraoperatively and scored in the exact same fashion. Individual surgical case logs were reviewed and surgical case volume was documented. There was no difference between the 2 groups after initial simulation testing and there was no correlation between case volume and initial scores. After training, the simulation group improved as compared with baseline in mean ASSET (p = 0.023) and mean time to completion (p = 0.01). After 1 year, there was no difference between the groups in any outcome measurements. Although individual technical skills can be cultivated with surgical simulation training, these advancements can be lost without continued education. It is imperative that residency programs implement a simulation curriculum and continue to train throughout the academic year. Published by Elsevier Inc.

Fatigue limit of monolithic Y-TZP three-unit-fixed dental prostheses: Effect of grinding at the gingival zone of the connector.

PubMed

Amaral, Marina; Villefort, Regina F; Melo, Renata Marques; Pereira, Gabriel K R; Zhang, Yu; Valandro, Luiz Felipe; Bottino, Marco Antonio

2017-08-01

To determine the fatigue limits of three-unit monolithic zirconia fixed dental prosthesis (FDPs) before and after grinding of the gingival areas of connectors with diamond burs. FDPs were milled from pre-sintered blocks of zirconia simulating the absence of the first mandibular molar. Half of the specimens were subjected to grinding, simulating clinical adjustment, and all of them were subjected to glazing procedure. Additional specimens were manufactured for roughness analysis. FDPs were adhesively cemented onto glass-fiber reinforced epoxy resin abutments. Fatigue limits and standard deviations were obtained using a staircase fatigue method (n=20, 100,000 loading cycles/5Hz). The initial test load was 70% of the mean load-to-fracture (n=3) and load increments were 5% of the initial test load for both the control and ground specimens. Data were compared by Student's T-test (α≤0.05). Both the control and ground groups exhibited similar values of load-to-fracture and fatigue limits. Neither the surface treatments nor ageing affected the surface roughness of the specimens. The damage induced by grinding with fine-grit diamond bur in the gingival area of the connectors did not decrease the fatigue limit of the three-unit monolithic zirconia FDP. Copyright © 2017 Elsevier Ltd. All rights reserved.

Initial construct validity evidence of a virtual human application for competency assessment in breaking bad news to a cancer patient.

PubMed

Guetterman, Timothy C; Kron, Frederick W; Campbell, Toby C; Scerbo, Mark W; Zelenski, Amy B; Cleary, James F; Fetters, Michael D

2017-01-01

Despite interest in using virtual humans (VHs) for assessing health care communication, evidence of validity is limited. We evaluated the validity of a VH application, MPathic-VR, for assessing performance-based competence in breaking bad news (BBN) to a VH patient. We used a two-group quasi-experimental design, with residents participating in a 3-hour seminar on BBN. Group A (n=15) completed the VH simulation before and after the seminar, and Group B (n=12) completed the VH simulation only after the BBN seminar to avoid the possibility that testing alone affected performance. Pre- and postseminar differences for Group A were analyzed with a paired t -test, and comparisons between Groups A and B were analyzed with an independent t -test. Compared to the preseminar result, Group A's postseminar scores improved significantly, indicating that the VH program was sensitive to differences in assessing performance-based competence in BBN. Postseminar scores of Group A and Group B were not significantly different, indicating that both groups performed similarly on the VH program. Improved pre-post scores demonstrate acquisition of skills in BBN to a VH patient. Pretest sensitization did not appear to influence posttest assessment. These results provide initial construct validity evidence that the VH program is effective for assessing BBN performance-based communication competence.

Initial construct validity evidence of a virtual human application for competency assessment in breaking bad news to a cancer patient

PubMed Central

Guetterman, Timothy C; Kron, Frederick W; Campbell, Toby C; Scerbo, Mark W; Zelenski, Amy B; Cleary, James F; Fetters, Michael D

2017-01-01

Background Despite interest in using virtual humans (VHs) for assessing health care communication, evidence of validity is limited. We evaluated the validity of a VH application, MPathic-VR, for assessing performance-based competence in breaking bad news (BBN) to a VH patient. Methods We used a two-group quasi-experimental design, with residents participating in a 3-hour seminar on BBN. Group A (n=15) completed the VH simulation before and after the seminar, and Group B (n=12) completed the VH simulation only after the BBN seminar to avoid the possibility that testing alone affected performance. Pre- and postseminar differences for Group A were analyzed with a paired t-test, and comparisons between Groups A and B were analyzed with an independent t-test. Results Compared to the preseminar result, Group A’s postseminar scores improved significantly, indicating that the VH program was sensitive to differences in assessing performance-based competence in BBN. Postseminar scores of Group A and Group B were not significantly different, indicating that both groups performed similarly on the VH program. Conclusion Improved pre–post scores demonstrate acquisition of skills in BBN to a VH patient. Pretest sensitization did not appear to influence posttest assessment. These results provide initial construct validity evidence that the VH program is effective for assessing BBN performance-based communication competence. PMID:28794664

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gehin, Jess C; Godfrey, Andrew T; Evans, Thomas M

The Consortium for Advanced Simulation of Light Water Reactors (CASL) is developing a collection of methods and software products known as VERA, the Virtual Environment for Reactor Applications, including a core simulation capability called VERA-CS. A key milestone for this endeavor is to validate VERA against measurements from operating nuclear power reactors. The first step in validation against plant data is to determine the ability of VERA to accurately simulate the initial startup physics tests for Watts Bar Nuclear Power Station, Unit 1 (WBN1) cycle 1. VERA-CS calculations were performed with the Insilico code developed at ORNL using cross sectionmore » processing from the SCALE system and the transport capabilities within the Denovo transport code using the SPN method. The calculations were performed with ENDF/B-VII.0 cross sections in 252 groups (collapsed to 23 groups for the 3D transport solution). The key results of the comparison of calculations with measurements include initial criticality, control rod worth critical configurations, control rod worth, differential boron worth, and isothermal temperature reactivity coefficient (ITC). The VERA results for these parameters show good agreement with measurements, with the exception of the ITC, which requires additional investigation. Results are also compared to those obtained with Monte Carlo methods and a current industry core simulator.« less

Mixed reality temporal bone surgical dissector: mechanical design.

PubMed

Hochman, Jordan Brent; Sepehri, Nariman; Rampersad, Vivek; Kraut, Jay; Khazraee, Milad; Pisa, Justyn; Unger, Bertram

2014-08-08

The Development of a Novel Mixed Reality (MR) Simulation. An evolving training environment emphasizes the importance of simulation. Current haptic temporal bone simulators have difficulty representing realistic contact forces and while 3D printed models convincingly represent vibrational properties of bone, they cannot reproduce soft tissue. This paper introduces a mixed reality model, where the effective elements of both simulations are combined; haptic rendering of soft tissue directly interacts with a printed bone model. This paper addresses one aspect in a series of challenges, specifically the mechanical merger of a haptic device with an otic drill. This further necessitates gravity cancelation of the work assembly gripper mechanism. In this system, the haptic end-effector is replaced by a high-speed drill and the virtual contact forces need to be repositioned to the drill tip from the mid wand. Previous publications detail generation of both the requisite printed and haptic simulations. Custom software was developed to reposition the haptic interaction point to the drill tip. A custom fitting, to hold the otic drill, was developed and its weight was offset using the haptic device. The robustness of the system to disturbances and its stable performance during drilling were tested. The experiments were performed on a mixed reality model consisting of two drillable rapid-prototyped layers separated by a free-space. Within the free-space, a linear virtual force model is applied to simulate drill contact with soft tissue. Testing illustrated the effectiveness of gravity cancellation. Additionally, the system exhibited excellent performance given random inputs and during the drill's passage between real and virtual components of the model. No issues with registration at model boundaries were encountered. These tests provide a proof of concept for the initial stages in the development of a novel mixed-reality temporal bone simulator.

MATD Operational Phase: Experiences and Lessons Learned

NASA Astrophysics Data System (ADS)

Messidoro, P.; Bader, M.; Brunner, O.; Cerrato, A.; Sembenini, G.

2004-08-01

The Model And Test Effectiveness Database (MATD) initiative is ending the first year of its operational phase. MATD represents a common repository of project data, Assembly Integration and Verification (AIV) data, on ground and flight anomalies data, of recent space projects, and offers, with the application of specific methodologies, the possibility to analyze the collected data in order to improve the test philosophies and the related standards. Basically the following type of results can be derived from the database: - Statistics on ground failures and flight anomalies - Feed-back from the flight anomalies to the Test Philosophies - Test Effectiveness evaluation at system and lower levels - Estimate of the index of effectiveness of a specific Model and Test Philosophy in comparison with the applicable standards - Simulation of different Test philosophies and related balancing of Risk/cost/schedule on the basis of MATD data The paper after a short presentation of the status of the MATD initiative, summarises the most recent lessons learned which are resulting from the data analysis and highlights how MATD is being utilized for the actual risk/cost/schedule/Test effectiveness evaluations of the past programmes so as for the prediction of the new space projects.